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UBC Theses and Dissertations

The role of specific substrates in excess biological phosphorus removal Rabinowitz, Barry 1985

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THE ROLE OF SPECIFIC SUBSTRATES IN EXCESS BIOLOGICAL PHOSPHORUS REMOVAL by BARRY RABINOWITZ B.Sc.(Eng), University of Cape Town, 1977 M.Sc.(Eng), University of Cape Town, 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Department of C i v i l Engineering) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October 1985 ® Barry Rabinowitz, 19 85 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by h i s or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of C i v i l Engineering The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date December 20, 1985 DE-6 (3/81) ABSTRACT The" p r i n c i p l e o b j e c t i v e s of t h i s r e s e a r c h were t o i n v e s t i g a t e t he r o l e o f s p e c i f i c carbonaceous s u b s t r a t e s i n t h e excess b i o l o g i c a l phosphorus (P) remova l mechanism and to o p t i m i z e t h e d e s i g n of t he n u t r i e n t remova l a c t i v a t e d s ludge p r o c e s s so as to max imize t h e a v a i l a b i l i t y o f t hese s u b s t r a t e s to t h e m i c r o - o r g a n i s m s i n v o l v e d i n the P remova l mechanism. The e x p e r i m e n t a l work r e p o r t e d i n t h i s t h e s i s was d i v i d e d i n t o t h e f o l l o w i n g f o u r p a r t s : 1) A s e r i e s of l a b o r a t o r y - s c a l e a n a e r o b i c b a t c h t e s t s wh ich were d e s i g n e d to s i m u l a t e the c o n d i t i o n s p r e s e n t i n t h e a n a e r o b i c zone o f the p r o c e s s . The o b j e c t i v e s of t h e b a t c h t e s t s were t o d e t e r m i n e wh ich s u b s t r a t e s were most e f f e c t i v e i n i n d u c i n g a n a e r o b i c P r e l e a s e , t he f a t e o f t h e s u b s t r a t e and i t s r o l e i n the P r e l e a s e mechanism, and t o q u a n t i f y t h e n e g a t i v e e f f e c t o f the p resence o f n i t r a t e i n the a n a e r o b i c zone on t h e P r e l e a s e mechanism. 2) A s e r i e s of p i l o t - s c a l e e x p e r i m e n t s i n wh ich sodium a c e t a t e was added t o a s i m p l i f i e d n u t r i e n t remova l a c t i v a t e d s ludge p r o c e s s w i t h the v iew t o d e t e r m i n i n g what c o n c e n t r a t i o n o f added s u b s t r a t e i s r e q u i r e d to r e l i a b l y induce excess b i o l o g i c a l P remova l i n the p r o c e s s . 3) A p i l o t - s c a l e p r i m a r y s ludge f e r m e n t a t i o n s t u d y i n wh ich t h e o b j e c t i v e was t o d e t e r m i n e the n a t u r e o f , and t h e g u a n t i t y o f s i m p l e carbonaceous s u b s t r a t e s t h a t can be p roduced o n - s i t e a t an a c t i v a t e d s ludge t r e a t m e n t p l a n t , and the o p t i m a l f e r m e n t e r o p e r a t i n g c o n d i t i o n s f o r such p r o d u c t i o n . 4) A s e r i e s of p i l o t - s c a l e e x p e r i m e n t s i n wh ich p r i m a r y s ludge f e r m e n t a t i o n was i n c o r p o r a t e d i n t o t h e d e s i g n o f a s i m p l i f i e d n u t r i e n t removal a c t i v a t e d s ludge p r o c e s s and the UCT process in order to gauge to what extent the P removal ch a r a c t e r i s t i c s of these processes can be enhanced by such modification. Results of the batch tests show that the simpler short-chain v o l a t i l e fatty acids (VFA's) acetate and propionate are the most eff e c t i v e in inducing anaerobic P release i n activated sludge. Batch tests in which a range of sodium acetate concentrations was fed into the flasks showed that P release and substrate u t i l i z a t i o n are integral parts of the same exchange phenomenon with a molar exchange r a t i o of 1.76 moles of acetate (as HAc) u t i l i z e d per mole of P released by the micro-organisms. With regard to the detrimental e f f e c t of n i t r a t e on the P release mechanism, i t appears as i f the available substrate required for the excess b i o l o g i c a l P removal mechanism i s u t i l i z e d i n the d e n i t r i f i c a t i o n reaction at a rate of 3.6 mg COD per mg NO3-N and i s thus rendered unavailable for the anaerobic P release mechanism. The addition of 86 mg/L (as COD) of sodium acetate to a s i m p l i f i e d nutrient removal process treating raw sewage resulted in excess b i o l o g i c a l P removal. However, such removal was achieved by the addition of only 39 mg/L (as COD) when the substrate was added to an unaerated zone that received zero influent n i t r a t e , confirming that the substrates required by the excess b i o l o g i c a l P removal mechanism are u t i l i z e d i n the d e n i t r i f i c a t i o n reaction, and the importance of adding any additional substrate into a n i t r a t e - f r e e zone. Operation of the p i l o t - s c a l e primary sludge fermenter showed that acetate and propionate, the two most important substrates in the excess - i v -b i o l o g i c a l P r e m o v a l mechanism, a r e a l s o t h e p r i n c i p l e p r o d u c t s o f p r i m a r y s l u d g e f e r m e n t a t i o n , making up more t h a n 95% of t h e t o t a l s h o r t - c h a i n VFA p r o d u c t i o n . Optimum VFA y i e l d s of 0.09 mg of VFA ( a s HAc) p e r mg of p r i m a r y s l u d g e ( as COD) were a c h i e v e d a t f e r m e n t e r s l u d g e ages i n t h e 3.5-5.0 day r a n g e . I n c o r p o r a t i o n o f p r i m a r y s l u d g e f e r m e n t a t i o n i n t o ' t h e d e s i g n of t h e s i m p l i f i e d n u t r i e n t r e m o v a l p r o c e s s r e s u l t e d i n an improvement of more t h a n 100% i n the P r e m o v a l c h a r a c t e r i s t i c s o f t h e p r o c e s s . The same m o d i f i c a t i o n t o a UCT p r o c e s s t h a t was p r e v i o u s l y e x h i b i t i n g some d e g r e e o f e x c e s s b i o l o g i c a l P r e m o v a l r e s u l t e d i n a f u r t h e r 5 0% improvement i n t h e P r e m o v a l c h a r a c t e r i s t i c s . A p r o p o s a l f o r t h e f u t u r e d e s i g n and o p e r a t i o n o f a p r i m a r y s l u d g e f e r m e n t e r f o r t h e enha n c e d P r e m o v a l a c t i v a t e d s l u d g e p r o c e s s t h a t f a c i l i t a t e s i n d e p e n d e n t f e r m e n t e r and p r o c e s s h y d r a u l i c a n d s o l i d s d e t e n t i o n time c o n t r o l i s a l s o o u t l i n e d . - v-TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS v LIST OF TABLES v i i i LIST OF FIGURES i x ACKNOWLEDGEMENT x i i CHAPTER ONE : INTRODUCTION 1 CHAPTER TWO : LITERATURE REVIEW 6 2.1. Excess B i o l o g i c a l P Removal ' 6 2.2. V o l a t i l e F a t t y A c i d P r o d u c t i o n by 30 P r i m a r y Sludge F e r m e n t a t i o n CHAPTER THREE : EXPERIMENTAL METHODS 3 7 3.1. A n a l y t i c a l Methods 37 3.2. Batch T e s t Procedure 39 3.3. P i l o t P l a n t O p e r a t i o n 41 3.3.1. Wastewater Source 41 3.3.2. A c t i v a t e d Sludge P r o c e s s 43 3.3.3. P i l o t P l a n t Fermenter 44 3.3.4. P i l o t P l a n t Sampling and A n a l y s i s 46 CHAPTER FOUR : BATCH TESTING RESULTS 48 4.1. The E f f e c t i v e n e s s of V a r i o u s S u b s t r a t e s a t I n d u c i n g 49 A n a e r o b i c P Release i n A c t i v a t e d Sludge 4.1.1. Experiment Using UBC P i l o t P l a n t Sludge 49 4.1.2. Experiment U s i n g Kelowna F u l l - S c a l e P l a n t 50 Sludge 4.2. The E f f e c t of V a r y i n g the C o n c e n t r a t i o n of a G i v e n 53 S u b s t r a t e on A n a e r o b i c P R e l e a s e and Subsequent A e r o b i c P Uptake i n A c t i v a t e d Sludge 4.2.1. Experiment U s i n g UBC P i l o t P l a n t Sludge 53 4.2.2. Experiment U s i n g D e n i t r i f i e d UBC P i l o t P l a n t 59 Sludge - v i -4.3. The E f f e c t of V a r y i n g t h e L e v e l of N i t r a t e f o r a 67 G i v e n I n i t i a l S u b s t r a t e C o n c e n t r a t i o n on A n a e r o b i c P R e l e a s e and S u b s e q u e n t P Uptake i n A c t i v a t e d S l u d g e 4.3.1. E x p e r i m e n t U s i n g UBC P i l o t P l a n t S l u d g e and 67 E x c e s s S u b s t r a t e 4.3.2. E x p e r i m e n t U s i n g UBC P i l o t P l a n t S l u d g e and 73 L i m i t e d S u b s t r a t e CHAPTER FIVE : PILOT-SCALE SUBSTRATE ADDITION 81 5.1. V a r i o u s L e v e l s of Sodium A c e t a t e A d d i t i o n t o a 81 S i m p l i f i e d N u t r i e n t Removal P r o c e s s C o n f i g u r a t i o n 5.2. The E f f e c t of F e e d i n g Sodium A c e t a t e t o a Zone t h a t 86 R e c e i v e s a Z e r o N i t r a t e D i s c h a r g e CHAPTER SIX : PRIMARY SLUDGE FERMENTATION RESULTS 90 6.1. The E f f e c t of S l u d g e Age on VFA P r o d u c t i o n 91 6.2. The E f f e c t of T e m p e r a t u r e on VFA P r o d u c t i o n 95 6.3. The E f f e c t o f pH on VFA P r o d u c t i o n 97 CHAPTER SEVEN : THE USE OF PRIMARY SLUDGE FERMENTATION 101 IN THE ACTIVATED SLUDGE PROCESS 7.1. The Use o f t h e F e r m e n t e r i n the S i m p l i f i e d N u t r i e n t 102 Removal A c t i v a t e d S l u d g e P r o c e s s 7.1.1. C o n t r o l 102 7.1.2. E x p e r i m e n t 104 7.2. The Use o f t h e F e r m e n t e r i n the UCT P r o c e s s 107 7.2.1. C o n t r o l 108 7.2.2. E x p e r i m e n t 110 CHAPTER EIGHT : DISCUSSION OF RESULTS 114 8.1. I n t r o d u c t i o n 114 8.2. The E x c e s s B i o l o g i c a l P Removal Mechanism 114 8.3. The E f f e c t of N i t r a t e on E x c e s s B i o l o g i c a l P Removal 121 8.4. P r i m a r y S l u d g e F e r m e n t a t i o n 129 8.5. The Use of P r i m a r y S l u d g e F e r m e n t a t i o n i n t h e 132 N u t r i e n t Removal A c t i v a t e d S l u d g e P r o c e s s 8.6. F u t u r e D e s i g n and O p e r a t i o n a l C o n s i d e r a t i o n s 135 - v i i -CHAPTER NINE : CONCLUSIONS AND RECOMMENDATIONS 144 BIBLIOGRAPHY 150 APPENDIX A l : RAW DATA FROM CHAPTER FIVE 15 6 APPENDIX A2 : RAW DATA FROM CHAPTER SIX 16 4 APPENDIX A3 : RAW DATA FROM CHAPTER SEVEN 184 - v i i i -LIST OF TABLES Table No. T i t l e Page 3.1 P i l o t Plant Weekly Sampling Schedule showing 47 varios analyses 3.2 P i l o t Plant Weekly Data Logging Schedule 47 5.1 Results of Pilot-Scale Substrate Addition 83 Experiments 6.1 The Effect of Sludge Age on VFA Production from 93 Primary Sludge (Section 6.1) 6.2 The Effect of Temperature on VFA Production from 96 Primary Sludge (Section 6.2) 6.3 The Effect of pH on VFA Production from Primary 99 Sludge (Section 6.3) 7.1 The Use of Primary Sludge Fermentation i n the 105 Simplified Nutrient Removal Process (Section 7.1) 7.2 The Use of Primary Sludge Fermentation i n the UCT 111 Process (Section 7.2) 8.1 Mean P Concentrations and Net Changes i n P 128 Concentration i n Section 7.2 - i x -LIST OF FIGURES F i g . No. T i t l e Page 2.1 A e r o b i c P uptake i n a b a t c h t e s t u s i n g mixed l i q u o r 7 from a p r o c e s s e x h i b i t i n g e x c e s s b i o l o g i c a l P removal. Data r e p o r t e d by S r i n a t h e t a l . (1959). 2.2 A e r o b i c b a t c h t e s t on mixed l i q u o r from a p r o c e s s 7 e x h i b i t i n g e x c e s s b i o l o g i c a l P removal showing b o t h P uptake and r e l e a s e . Data r e p o r t e d by A l a r c o n (19 61). 2.3 A e r o b i c b a t c h t e s t sequence showing the e f f e c t of 10 a e r a t i o n i n t e n s i t y on P u p t a k e . Data r e p o r t e d by L e v i n and S h a p i r o (1965). 2.4 A b a t c h t e s t done under s e q u e n t i a l a e r a t e d and 10 unaerated c o n d i t i o n s showing P uptake and r e l e a s e . Data r e p o r t e d by W e l l s ( 1969). 2.5 D i s o l v e d oxygen and P c o n c e n t r a t i o n p r o f i l e s f o r 15 two p a r a l l e l a e r a t i o n t a n k s e x h i b i t i n g excess b i o l o g i c a l P r e m o v a l . Data r e p o r t e d S c a l f e t a l . ( 1969) . 2.6 4-stage Bardenpho n i t r i f i c a t i o n - d e n i t r i f i c a t i o n 19 p r o c e s s c o n f i g u r a t i o n . 2.7 Phoredox o r M o d i f i e d Bardenpho P r o c e s s c o n f i g u r a t i o n 19 f o r b i o l o g i c a l n i t r o g e n and phosphorus re m o v a l . 2.8 UCT P r o c e s s c o n f i g u r a t i o n f o r b i o l o g i c a l n i t r o g e n 19 and phosphorus r e m o v a l . 2.9 R e s u l t s from a l a b o r a t o r y - s c a l e UCT p r o c e s s showing 27 the e f f e c t of i n c r e a s i n g the c o n c e n t r a t i o n of r e a d i l y b i o d e g r a d a b l e COD i n the i n f l u e n t . Data r e p o r t e d by S i e b r i t z e t a l . ( 1983 ) . 2.10. (Top) R e s u l t s of a 10 r e a c t o r - i n - s e r i e s a n a e r o b i c / 28 a e r o b i c p r o c e s s showing P, Ca, and Mg p r o f i l e s . (Bottom) A c e t a t e p r o f i l e s i n the a n a e r o b i c zone immediately a f t e r c o n v e r s i o n from a p u r e l y a e r o b i c p r o c e s s and a f t e r s i x weeks of a c e t a t e a d d i t i o n . Data r e p o r t e d by Rensink (1981). 2.11 The e f f e c t of b a t c h r e a c t o r r e s i d e n c e time on 32 e f f l u e n t carbon d i s t r i b u t i o n . Data r e p o r t e d by Andrews and Pea r s o n ( 1965). 2.12 E f f l u e n t VFA d i s t r i b u t i o n as a f u n c t i o n of s l udge 32 age. Data r e p o r t e d by Andrews and Pearson (1965). -x-F i g . No. T i t l e Page 2.13 VFA p r o d u c t i o n by p r i m a r y s l u d g e f e r m e n t a t i o n a t 35 3 5 ° c . D a t a r e p o r t e d by Chynoweth a n d Man ( 1 9 7 5 ) . 2.14 S c h e m a t i c d i a g r a m o f a two-phase a n a e r o b i c d i g e s t o r 35 w i t h s e p a r a t i o n o f t h e a c i d a n d methane p r o d u c i n g p h a s e s by h y d r a u l i c c o n t r o l . A f t e r Gosh e t a l . ( 1 9 7 5 ) . 3.1 B a t c h t e s t i n g a p p a r a t u s . A f t e r Comeau ( 1984). 40 3.2 S c h e m a t i c l a y o u t of t h e p i l o t p l a n t on t h e U n i v e r s i t y 42 o f B r i t i s h C o l u m b i a campus. 3.3 M i x e d l i q u o r w a s t i n g c h a r t f o r s l u d g e age c o n t r o l 45 b a s e d on t h e e f f l u e n t t o t a l s o l i d s c o n c e n t r a t i o n . 4.1 P h o s p h o r u s r e l e a s e i n d u c e d i n UBC p i l o t p l a n t s l u d g e 51 u s i n g v a r i o u s s u b s t r a t e s . 4.2 P h o s p h o r u s r e l e a s e i n d u c e d i n K elowna p l a n t s l u d g e 51 u s i n g v a r i o u s s u b s t r a t e s . 4.3 O r t h o - P and n i t r a t e c o n c e n t r a t i o n and ORP p r o f i l e s : 5 6 The e f f e c t o f s u b s t r a t e c o n c e n t r a t i o n on a n a e r o b i c -57 P r e l e a s e - n i t r i f i e d s l u d g e ( S e c t i o n 4 . 2 . 1 ) . 4.4 O r t h o - P and a c e t a t e c o n c e n t r a t i o n and ORP p r o f i l e s : 61 The e f f e c t o f s u b s t r a t e c o n c e n t r a t i o n o n P r e l e a s e -62 and u p take - d e n i t r i f i e d s l u d g e ( S e c t i o n 4.2.2). 4.5 The e f f e c t of i n c r e a s i n g the i n i t i a l s u b s t r a t e 62 c o n c e n t r a t i o n on t h e ne t P r e l e a s e a f t e r 2 h o u r s i n S e c t i o n 4.2.2. 4.6 P h o s p h o r u s r e l e a s e v e r s u s s u b s t r a t e u t i l i z a t i o n i n 66 S e c t i o n 4.2.2. 4.7 A e r o b i c P u p t a k e v e r s u s a n a e r o b i c P r e l e a s e i n 66 S e c t i o n 4.2.2. 4.8 O r t h o - P and n i t r a t e c o n c e n t r a t i o n and ORP p r o f i l e s : 7 0 The e f f e c t o f n i t r a t e o n P r e l e a s e a n d u p t a k e - -71 e x c e s s s u b s t r a t e c o n d i t i o n s ( S e c t i o n 4 . 3 . 1 ) . 4.9 O r t h o - P , n i t r a t e and a c e t a t e c o n c e n t r a t i o n p r o f i l e s : 75 The e f f e c t o f n i t r a t e on P r e l e a s e a n d u p t a k e - -76 s u b s t r a t e l i m i t i n g c o n d i t i o n s ( S e c t i o n 4 . 3 . 2 ) . 4.10 E f f e c t o f i n c r e a s i n g t h e i n i t i a l n i t r a t e 78 c o n c e n t r a t i o n on P r e l e a s e i n S e c t i o n 4.3.2. - x i -F i g . No. T i t l e Page 4.11 Substrate u t i l i z a t i o n versus P release for the 78 control reactor i n Section 4.3.2. 7.1 The use of primary sludge fermentation in the 103 s i m p l i f i e d nutrient removal process - Control and Experimental process configurations. 7.2 The use of primary sludge fermentation in the UCT 109 process - Control and Experimental process conf igurations. 8.1 Simplified model for anaerobic and aerobic 120 metabolism of Bio-P bacteria. Adapted from Comeau et a l . (1985b). 8.2 Schematic layout of proposed method of operating 139 primary sludge fermenter having independent SRT and HRT control and no fermenter secondary c l a r i f i e r . 8.3 Mass balance chart showing the dependence of the dry 141 weight percent P content of the sludge on various process parameters and the sludge age. - x i i -ACKNOWLED GEMENT I wish to express my sincere thanks to the following: Dr W.K. Oldham, Head of the C i v i l Engineering Department at the University of B r i t i s h Columbia and supervisor of the b i o l o g i c a l phosphorus removal project. His enthusiastic support and advice given for the entire duration of this research i s much appreciated. My wonderful wife, Myrna, for her constant support and encouragement and for her assistance with the typing and proof-reading of the manuscript. Fred Koch, Research Associate at the Department of C i v i l Engineering, for his constructive advice and c r i t i c i s m and his assistance with the p i l o t - p l a n t operation and batch testing. The s t a f f of the Environmental Engineering Laboratory, Susan Liptak, Sue Jasper, Paula Parkinson and Jenny Chow for t h e i r invaluable assistance with much of the sample analysis. Fellow graduate students in Environmental Engineering, Yves Comeau, Ramanathan Manoharan and Ashok Gupta for t h e i r cheerful assistance with the batch testing. Guy Kirsch, technician i n the C i v i l Engineering workshops who was responsible for the maintenance of the p i l o t plant. Nigel Livingston, for his assistance with the computer graphics. This research was carried out under a grant from the Science Council of B r i t i s h Columbia, whose f i n a n c i a l assistance i s gr a t e f u l l y acknowledged. ABBREVIATIONS AND TERMINOLOGY Abb. F u l l Name Units COD Chemical Oxygen Demand mg COD/L MLSS Mixed Liquor Suspended Solids mg/L ORP Oxidation Reduction Potential mV (ref: Ag-AgCl) SVI Sludge Volume Index \/\ RBS Readily Biodegradable Substrate mg COD/L TKN Total Kjeldahl Nitrogen mg N/L VFA V o l a t i l e Fatty Acid mg HAc/L AP System Phosphorus Removal mg P/L ACOD System COD Removal mg COD/L The term "anaerobic" i s used somewhat d i f f e r e n t l y in environmental engineering than in microbiology. Microbiologists refer to an anaerobic state as being one i n which dissolved oxygen i s absent, but various forms of combined oxygen (e.g. nitrate) may or may not be present. In environmental engineering the term anaerobic implies the absence of a l l forms of bio-available dissolved oxygen, and the term "anoxic" i s used to define a state in which dissolved oxygen i s absent, but combined oxygen i s present. In this regard, the terminology adhered to i n this thesis i s that used in environmental engineering. - 1 -CHAPTER ONE INTRODUCTION The removal of phosphorus (P) from d o m e s t i c and i n d u s t r i a l wastewaters has become i n c r e a s i n g l y i m p o r t a n t i n r e c e n t y e a r s , p a r t i c u l a r l y i n the case of p r o c e s s e f f l u e n t streams b e i n g d i s c h a r g e d to i n l a n d w a t e r s . Phosphorus removal has been recommended even i n c a s e s where l i m n o l o g i c a l s t u d i e s have shown n i t r o g e n (N) to be t h e p r i m a r y , and P t h e secondary growth l i m i t i n g n u t r i e n t i n s u r f a c e water systems. The p r i n c i p l e r e a s o n f o r t h i s i s i n l a k e s where P d i s c h a r g e i s e x c e s s i v e but N i s l i m i t i n g , c o n d i t i o n s a r e o f t e n i d e a l f o r the development of l a r g e p o p u l a t i o n s of c e r t a i n s p e c i e s of b l u e - g r e e n a l g a e and o t h e r N - f i x i n g organisms. N i t r o g e n f i x a t i o n i s the p r o c e s s by which these organisms a r e a b l e to " f i x " a t m o s p h e r i c N, i . e . u t i l i z e N f o r b a s i c m e t a b o l i c purposes and i n c o r p o r a t e i t i n t o t h e i r c e l l mass. I n t h i s way a t m o s p h e r i c N e n t e r s the ecosystem i n an u n c o n t r o l l a b l e manner. The mass of P a v a i l a b l e to t h e organisms of a g i v e n ecosystem, however, i s s o l e l y a f u n c t i o n of the mass of P e n t e r i n g the system v i a the p o i n t and d i f f u s e s o u r c e s . The d i s c h a r g e of wastewaters a f t e r w i d e l y v a r y i n g degrees of t r e a t m e n t o f t e n r e p r e s e n t s the major P d i s c h a r g e c o n t r i b u t i o n by p o i n t s o u r c e s . For t h i s r e a s o n , much a t t e n t i o n has been focused on the removal of P i n p r o c e s s e s t r e a t i n g d o m e s t i c and i n d u s t r i a l w a s t e w aters. T h i s need has g i v e n r i s e to two b a s i c removal s t r a t e g i e s - c h e m i c a l and b i o l o g i c a l P r e m o v a l . - 2 -Chemical P removal i s a c h i e v e d by the a d d i t i o n of p r e c i p i t a t i n g c h e m i c a l s such as c a l c i u m ( C a ) , aluminum ( A l ) and i r o n (Fe) s a l t s . These c h e m i c a l s a r e e i t h e r added a t the p r i m a r y s t a g e , d i r e c t l y i n t o the p r o c e s s o r as a t e r t i a r y stage of t r e a t m e n t . Chemical t r e a t m e n t , a l t h o u g h g e n e r a l l y s u c c e s s f u l i n terms of a c h i e v i n g low e f f l u e n t P c o n c e n t r a t i o n s , s u f f e r s from a number of drawbacks. For example, i t c r e a t e s a s i g n i f i c a n t l y l a r g e r s o l i d s h a n d l i n g problem i n t h a t i n many cases l a r g e amounts of c h e m i c a l s l u d g e are produced t h a t r e q u i r e d i s p o s a l . The major d i s a d v a n t a g e of c h e m i c a l r e m o v a l , however, i s the c o s t of the p r e c i p i t a t i n g c h e m i c a l s . R i s i n g c h e m i c a l c o s t s , coupled w i t h the f a c t t h a t c h e m i c a l r e q u i r e m e n t s tend to i n c r e a s e d r a m a t i c a l l y f o r P removals to c o n c e n t r a t i o n s below about 1.5 mg/L, have made the c o s t of c h e m i c a l P removal p r o h i b i t i v e f o r many communities. The problems a s s o c i a t e d w i t h c h e m i c a l P r e m o v a l , as mentioned above, m o t i v a t e d r e s e a r c h workers i n many p a r t s of the w o r l d to i n v e s t i g a t e b i o l o g i c a l P removal w i t h s p e c i a l r e f e r e n c e to e x c e s s b i o l o g i c a l P r e m o v a l . E x c e s s b i o l o g i c a l P removal i s the phenomenon whereby a s i g n i f i c a n t f r a c t i o n of the organisms p r e s e n t i n the a c t i v a t e d s l u d g e p r o c e s s remove a l a r g e r mass of P from the incoming wastewater than t h a t which they r e q u i r e f o r b a s i c m e t a b o l i c p u r p o s e s . T h i s e x c e s s P i s g e n e r a l l y thought to be s t o r e d by the organisms i n the form of l o n g c h a i n s of i n o r g a n i c p o l y p h o s p h a t e known as v o l u t i n g r a n u l e s . I t i s g e n e r a l l y assumed t h a t P makes up a p p r o x i m a t e l y 1.5 p e r c e n t of the dry weight of c e l l s t h a t have no s t o r e d p o l y p h o s p h a t e (Hoffmann and M a r a i s , 19 77). E x c e s s P removal i s assumed to -3-be occurring when the measured dry weight percent P in the waste activated sludge from a process exceeds this amount. Excess P i s removed from such a process by the sludge wasted each day. A comprehensive history of excess b i o l o g i c a l P removal and i t s e ffect on the development of the enhanced P removal activated sludge process i s presented in Chapter Two. Ever since 1959, when excess P removal was f i r s t reported by Srinath, Sastry and P i l l a i in India, there has been considerable debate as to whether the phenomenon i s a purely b i o l o g i c a l one or a b a c t e r i a l l y mediated chemical p r e c i p i t a t i o n . However, the vast majority of research has indicated that excess P removal i n the activated sludge process i s primarily b i o l o g i c a l i n nature, although removal by chemical p r e c i p i t a t i o n does occur to a l e s s e r extent. Reasons cited for this are that the pH range present in most processes and the presence of large amounts of organic material are unfavourable for the rapid p r e c i p i t a t i o n of calcium phosphate. Excess P removal was reported in the mid 19 60's i n plug flow high rate activated sludge processes (Scalf et al ., 19 69) and l a t e r in the 19 70's i n single sludge n i t r i f i c a t i o n -denitr i f i c ation processes (Barnard, 1974, 19 76). Furthermore, i t was noted that in a l l cases where the phenomenon occurred, the sludge was subjected to anaerobic conditions of such an intensity that P release from the sludge into the supernatent occurred. Upon entering a zone where aerobic conditions existed, the released as well as excess concentrations of P were taken up, - 4 -r e s u l t i n g i n system e x c e s s P r e m o v a l . I t was h y p o t h e s i z e d t h a t the e x c e s s b i o l o g i c a l P removal was a consequence of P r e l e a s e having taken p l a c e and t h a t the r e l e a s e was the r e s u l t of the sludge b e i n g s u b j e c t e d to a c e r t a i n degree of a n a e r o b i c s t r e s s . Research work was then focused on a t t e m p t i n g to q u a n t i f y the degree of s t r e s s r e q u i r e d to r e l i a b l y induce e x c e s s b i o l o g i c a l P r e m o v a l . The measurement of o x i d a t i o n - r e d u c t i o n p o t e n t i a l (ORP), which i s based on the r a t i o of the sums of the t o t a l o x i d i z e d and reduced s p e c i e s p r e s e n t i n a g i v e n s o l u t i o n , was chosen to q u a n t i f y the degree of a n a e r o b i o s i s r e q u i r e d . A l t h o u g h ORP measurement i s r e l a t i v e l y s i m p l e i n pure s o l u t i o n s , i t was thought to be u n r e l i a b l e i n a c t i v a t e d s l u d g e mixed l i q u o r . I n a d d i t i o n , i t was found t h a t i t was not p o s s i b l e to a c c u r a t e l y d e f i n e the r e q u i r e m e n t s f o r e x c e s s b i o l o g i c a l P removal i n terms of a n a e r o b i c s t r e s s a l o n e . I n the e a r l y 19 80's, i t was found t h a t P r e l e a s e was more c l o s e l y r e l a t e d to t h e c o n c e n t r a t i o n and n a t u r e of s u b s t r a t e a v a i l a b l e to t h e m i c r o - o r g a n i s m s under a n a e r o b i c c o n d i t i o n s , than to a degree of s t r e s s o b t a i n e d i n the a n a e r o b i c zone. T h i s s h i f t i n emphasis from a n a e r o b i c s t r e s s q u a n t i f i c a t i o n to the n a t u r e of the s u b s t r a t e a v a i l a b l e to t h e m i c r o - o r g a n i s m s under a n a e r o b i c c o n d i t i o n s gave r i s e to t h e concept of s p e c i f i c s u b s t r a t e induced e x c e s s b i o l o g i c a l P r e m o v a l . T h i s t h e s i s o u t l i n e s the i n v e s t i g a t i o n of the use of v a r i o u s s u b s t r a t e s i n an attempt to determine which s u b s t r a t e s a r e most e f f e c t i v e i n i n d u c i n g P r e l e a s e and what c o n c e n t r a t i o n s of the s u b s t r a t e s a r e -5-required. Evidence w i l l be presented that c l e a r l y demonstrates short chain v o l a t i l e fatty acids (VFA's) and t h e i r salt forms to be preferred substrates. The development of a s i m p l i f i e d n i t r i f i c a t i o n - d e n i t r i f i c a t i o n process configuration, that requires a minimum addition of the preferred substrates in order to r e l i a b l y induce excess b i o l o g i c a l P removal, i s described. An additional part of this research involves the on-site production of short chain VFA's by the fermentation of primary sewage sludge to be used in the subsequent process. In th i s manner, a form of treatment was developed i n which excess P removal i s achieved i n processes treating low organic strength wastewaters without the addition of either additional substrate or p r e c i p i t a t i n g chemicals. -6-CHAPTER TWO LITERATURE REVIEW T h i s r e s e a r c h d e a l s w i t h two p r e v i o u s l y u n r e l a t e d a r e a s of wastewater t r e a t m e n t , e x c e s s b i o l o g i c a l phosphorus removal and p r i m a r y sludge f e r m e n t a t i o n w i t h the o b j e c t i v e of m a x i m i z i n g v o l a t i l e f a t t y a c i d p r o d u c t i o n . A b r i e f o v e r v i e w of the a v a i l a b l e l i t e r a t u r e c o v e r i n g these two a r e a s w i l l be p r e s e n t e d i n S e c t i o n s 2.1 and 2.2, r e s p e c t i v e l y . 2.1. Excess B i o l o g i c a l P Removal Comprehensive l i t e r a t u r e r e v iews of e x c e s s b i o l o g i c a l P removal have been p r e s e n t e d by S i e b r i t z e t a l . ( 19 83 ), Comeau ( 1984) and o t h e r s . As such, o n l y a b r i e f r e v i e w of the p r i n c i p l e r e s e a r c h w i l l be p r e s e n t e d i n o r d e r to p l a c e i t i n an h i s t o r i c a l p e r s p e c t i v e w i t h r e c e n t r e s e a r c h b e i n g d e s c r i b e d i n g r e a t e r d e t a i l . E x cess b i o l o g i c a l P removal was f i r s t r e p o r t e d by S r i n a t h e t a l . ( 1959) i n I n d i a , and by A l a r c o n (1961) who conducted a e r o b i c b a t c h t e s t s on mixed l i q u o r taken from a c t i v a t e d s l u d g e p r o c e s s e s e x h i b i t i n g e x c e s s P r e m o v a l . I n b o t h c a s e s the mixed l i q u o r was combined w i t h raw sewage and v e r y r a p i d i n i t i a l P uptake was o b s e r v e d . T h e i r r e s u l t s are p r e s e n t e d i n F i g s . 2.1 and 2.2, r e s p e c t i v e l y . Furthermore, A l a r c o n (1961) noted t h a t i f a e r a t i o n was a l l o w e d to c o n t i n u e f o r a number of h o u r s , a r e l e a s e of P from the sludge back i n t o the s u p e r n a t a n t o c c u r r e d . S r i n a t h e t a l . n oted t h a t the degree of P uptake appeared to be r e l a t e d to 0 I 2 3 4 5 6 T i m e ( h o u r s ) F i g . 2.1. A e r o b i c P uptake i n a b a t c h t e s t u s i n g mixed l i q u o r from a p r o c e s s e x h i b i t i n g e x c e s s b i o l o g i c a l P r e m o v a l . Data r e -p o r t e d by S r i n a t h e t a l . (1959). 10 12 14 16 18 20 22 24 26 T i m e ( h o u r s ) F i g . 2.2. A e r o b i c b a t c h t e s t on mixed l i q u o r from a p r o c e s s e x h i b i t i n g e x c e s s b i o l o g i c a l P removal showing b o t h P uptake and r e -l e a s e . Data r e p o r t e d by A l a r c o n (19 6 1 ) . - 8 -the sludge c o n c e n t r a t i o n . w h i l e A l a r c o n r e p o r t e d t h a t t h e degree of uptake was a f u n c t i o n of the i n t e n s i t y of a e r a t i o n . N e i t h e r S r i n a t h e t a l . nor A l a r c o n o f f e r e d any e x p l a n a t i o n f o r why e x c e s s P uptake o c c u r r e d o r why c e r t a i n t r e a t m e n t f a c i l i t i e s e x h i b i t e d e x c e s s P removal w h i l e o t h e r s d i d n o t . The f i r s t attempt to e s t a b l i s h which p r o c e s s o p e r a t i o n a l parameters enhance removal was c a r r i e d out by Feng ( 19 62 ) i n a s e r i e s of ba t c h t e s t s on sludge o b t a i n e d from t h e Nine S p r i n g s Sewage Treatment P l a n t i n Madison, W i s c o n s i n . He concluded t h a t the c o n d i t i o n s f a v o u r i n g e x c e s s P removal were a p r o c e s s temperature around 25°C, adequate a e r a t i o n and a c o r r e c t f o o d / micro-organism (F/M) r a t i o . I t s h o u l d be n o t e d , however, t h a t the above c o n d i t i o n s a re o f t e n found i n p r o c e s s e s not e x h i b i t i n g e x c e s s P removal. Of g r e a t e r s i g n i f i c a n c e was Feng's f i n d i n g t h a t inadequate a e r a t i o n a d v e r s e l y a f f e c t e d P uptake and, i n some c a s e s , even r e s u l t e d i n the r e l e a s e of P back i n t o the s u p e r n a t a n t . The f i r s t r e s e a r c h e r s to propose a b i o c h e m i c a l b a s i s f o r e x c e s s P removal were L e v i n and S h a p i r o ( 1965). They noted the i m p o r t a n t r o l e of P i n the a e r o b i c u t i l i z a t i o n of c a r b o h y d r a t e s , and t h a t the l i t e r a t u r e had i n d i c a t e d the a b i l i t y of c e r t a i n f u n g i , a l g a e and b a c t e r i a t o s t o r e P i n l o n g c h a i n s of i n o r g a n i c p o l y - P c a l l e d v o l u t i n g r a n u l e s . H a r o l d ( 1966) p r e s e n t s an e x c e l l e n t r e v i e w of l i t e r a t u r e a v a i l a b l e on p o l y p h o s p h a t e a c c u m u l a t i o n . He s u g g e s t s t h a t , from an e v o l u t i o n a r y p o i n t of v i e w , p o l y p h o s p h a t e may p r e d a t e adenosine t r i p h o s p h a t e (ATP) a s the p r i n c i p l e energy -9-c a r r i e r of the c e l l . He p o i n t e d out t h a t the a b i l i t y to s t o r e e x c e s s P g i v e s the organisms an advantage o v e r organisms not h a v i n g t h i s a b i l i t y but t h a t t h e r e was no c l a r i t y as to whether p o l y - P a c c u m u l a t i o n s e r v e s as an energy s t o r a g e , o r s i m p l y a P s t o r a g e f u n c t i o n . L e v i n and S h a p i r o conducted a s e r i e s of b a t c h e x p e r i m e n t s on sludge o b t a i n e d from the D i s t r i c t of Columbia Sewage Treatment P l a n t , a s h o r t sludge age o r " h i g h r a t e " p r o c e s s . I n one e xperiment samples were a e r a t e d w i t h and w i t h o u t the a d d i t i o n of v a r i o u s s u b s t r a t e s ( g l u c o s e , s u c c i n a t e , e t c . ) . I t was found t h a t a l t h o u g h P uptake was o b t a i n e d i n b o t h c a s e s , the magnitude and r a t e of P uptake was g r e a t e r i n r e a c t o r s r e c e i v i n g s u b s t r a t e a d d i t i o n than i n the c o n t r o l r e a c t o r s , i . e . t h a t the presence of carbonaceous s u b s t r a t e promoted the uptake of P. They c o n f i r m e d the f i n d i n g s of A l a r c o n (1961), t h a t i n the samples k e p t under a e r o b i c c o n d i t i o n s f o r l o n g p e r i o d s of t i m e , P r e l e a s e took p l a c e . T h i s phenomenon i n d i c a t e d to them t h a t P s t o r a g e t a k e s p l a c e a e r o b i c a l l y by the a c t i v e f r a c t i o n of the s l u d g e and t h a t w i t h t i m e , the r e d u c t i o n of the a c t i v e mass by c e l l l y s i s and endogenous r e s p i r a t i o n r e s u l t s i n the r e l e a s e of the a s s o c i a t e d s t o r e d P. I n a n o t h e r e x p e r i m e n t d e s i g n e d to demonstrate the r o l e of the s l u d g e a c t i v e f r a c t i o n i n P u p t a k e , L e v i n and S h a p i r o a e r a t e d a s e r i e s of r e a c t o r s w i t h v a r y i n g degrees of i n t e n s i t y , one r e a c t o r r e m a i n i n g a n a e r o b i c . From t h e i r r e s u l t s , p r e s e n t e d i n F i g . 2.3, i t can be seen t h a t P uptake was observed i n the a e r o b i c r e a c t o r s -10-o. E a . i o* 0. TJ a> _> o (A tn Aeration Rate(mL/sec/ l500mL) = 0 .5 mM/L succ inate + 0.5mM/L glucose added to each batch T i m e ( h o u r s ) Fig. 2.3. Aerobic batch test sequence showing the e f f e c t of aeration i n t e n s i t y on P uptake. Data reported by Levin and Shapiro (1965) CL E CL I O* Q. © o Vt F i g . 2.4. A batch test done under seguential aerated and unaerated conditions showing P uptake and release. Data reported by Wells (1969). -11-but i n the a n a e r o b i c r e a c t o r P r e l e a s e o c c u r r e d . Furthermore, the uptake of P was r e l a t e d to the i n t e n s i t y of a e r a t i o n a t the l o wer a e r a t i o n r a t e s but f o r h i g h e r r a t e s of a e r a t i o n no improvement i n P uptake was o b s e r v e d . They h y p o t h e s i z e d t h a t P uptake was the r e s u l t of ATP f o r m a t i o n by o x i d a t i v e p h o s p h o r y l a t i o n i n the a e r o b i c Krebs c y c l e w i t h oxygen s e r v i n g as the f i n a l e l e c t r o n a c c e p t o r . However, no e x p l a n a t i o n was o f f e r e d f o r the r e l e a s e of P under a n a e r o b i c c o n d i t i o n s and whether t h i s was i n any way r e l a t e d to e x c e s s P u p t a k e . S h a p i r o , L e v i n and Zea ( 1967) l a t e r demonstrated the r e v e r s i b i l i t y of the uptake phenomenon, i . e . t h a t a sample l e f t under a n a e r o b i c c o n d i t i o n s would r e l e a s e P, but the r e l e a s e d P would s u b s e q u e n t l y d i s a p p e a r from s o l u t i o n upon a e r a t i o n of the sample. L e v i n and S h a p i r o (1965) a l s o demonstrated t h a t the p r i n c i p l e e x c e s s P removal mechanism i s of a b i o l o g i c a l n a t u r e r a t h e r than a c h e m i c a l p r e c i p i t a t i o n . T h i s was done by h a v i n g a s e r i e s of b a t c h r e a c t o r s m a i n t a i n e d i n the pH range where c a l c i u m phosphate o c c u r s w i t h no improvement i n P uptake o v e r an u n c o n t r o l l e d r e a c t o r , and by d e m o n s t r a t i n g the i n h i b i t o r y e f f e c t s of 2 , 4 - d i n i t r o p h e n o l on a e r o b i c uptake. D i n i t r o p h e n o l i s known to i n h i b i t ATP p r o d u c t i o n and the t r a n s p o r t mechanism of the c e l l , i n d i c a t i n g the b i o l o g i c a l n a t u r e of the removal mechanism. W e l l s ( 1969) c o n f i r m e d the f i n d i n g s of L e v i n and S h a p i r o r e g a r d i n g the r e v e r s i b i l i t y of the uptake mechanism by u s i n g sludge from the San-Antonio p l a n t , which was e x h i b i t i n g e x c e s s P removal a t the t i m e . A b a t c h t h a t was s e q u e n t i a l l y a e r a t e d d u r i n g the day and l e f t u n a erated a t n i g h t r e l e a s e d P under - 1 2 -a n a e r o b i c c o n d i t i o n s and took up P under a e r o b i c c o n d i t i o n s (See F i g . 2 . 4 ) . Note t h a t b o t h the up take and r e l e a s e dec reased p r o g r e s s i v e l y w i t h each o f the c y c l e s , p r o b a b l y due t o t h e decrease of t he a c t i v e f r a c t i o n of the s ludge w i t h t i m e . I t was W e l l s who f i r s t r e p o r t e d the s i g n i f i c a n c e o f t he s ludge c h a r a c t e r i s t i c s by n o t i n g t h a t the s l u d g e s f rom d i f f e r e n t p l a n t s behaved i n an e n t i r e l y d i f f e r e n t manner when s u b j e c t e d t o i d e n t i c a l b a t c h t e s t c o n d i t i o n s . M i l b u r y e t a l . ( 1970) c o n f i r m e d the f i n d i n g s o f L e v i n and S h a p i r o w i t h r e g a r d t o t he s i g n i f i c a n c e o f i n t e n s i t y o f a e r a t i o n i n a b a t c h s t u d y . They found t h a t h i g h P u p t a k e c o u l d be a c h i e v e d p r o v i d e d t h a t the d i s s o l v e d oxygen was k e p t a t a minimum c o n c e n t r a t i o n o f 0 .2 mg /L . I n c r e a s i n g the d i s s o l v e d oxygen c o n c e n t r a t i o n beyond t h i s l e v e l d i d n o t s i g n i f i c a n t l y improve t h e P u p t a k e . D u r i n g the p e r i o d f rom t h e l a t e 1960 ' s t i l l t he m i d - 1 9 7 0 ' s , r e s e a r c h i n t o t he P remova l mechanism c o n c e n t r a t e d on e s t a b l i s h i n g w h e t h e r remova l was p r i n c i p l y b i o l o g i c a l o r chemica l i n n a t u r e . P roponen ts o f t he the chemica l remova l h y p o t h e s i s reasoned t h a t the r e s u l t a n t i n c r e a s e i n pH due t o C02 s t r i p p i n g by a e r a t i o n wou ld c r e a t e c o n d i t i o n s f a v o u r a b l e f o r c a l c i u m phosphate p r e c i p i t a t i o n . Vacker e t a l . (1967) and Y a l l e t a l . (1970) found t h a t i n o r g a n i c p r e c i p i t a t i o n p l a y e d a m i n o r r o l e i n P remova l by m o n i t o r i n g C a + + , M g + + and P c o n c e n t r a t i o n changes i n t h e i r e x p e r i m e n t s . Bargman e t a l . (1970) conduc ted a e r o b i c b a t c h t e s t s on s ludge f rom d i f f e r e n t p l a n t s , s p i k e d w i t h -13-s e t t l e d sewage, a t an e l e v a t e d pH of about 7.9. The sludge used i n these b a t c h t e s t s came from two d i f f e r e n t p l a n t s , o n l y one of which was e x h i b i t i n g e x c e s s P r e m o v a l . I n s p i t e of the f a c t t h a t the pH i n b o t h r e a c t o r s was k e p t a t around the same v a l u e , s i g n i f i c a n t P uptake was o n l y observed i n the r e a c t o r having sludge from the p l a n t e x h i b i t i n g e x c e s s P r e m o v a l . From t h e i r e x p e r i m e n t , Bargman e t a l . co n c l u d e d t h a t the e x c e s s uptake was a f u n c t i o n of some c h a r a c t e r i s t i c of the s l u d g e and not due to i n o r g a n i c p r e c i p i t a t i o n . Hoffmann and M a r a i s ( 1977) attempted to s e p a r a t e out the mass of P t a k e n up b i o l o g i c a l l y and by c a l c i u m phosphate p r e c i p i t a t i o n i n two l a b o r a t o r y s c a l e a c t i v a t e d s l u d g e p r o c e s s e s . The p r o c e s s e s were two-stage and i d e n t i c a l e x c e p t t h a t one was p u r e l y a e r o b i c and the o t h e r a n o x i c - a e r o b i c , i . e . the " a n o x i c " r e a c t o r had n i t r a t e but no d i s s o l v e d oxygen p r e s e n t . B a t c h t e s t s were conducted on s l u d g e from the two p r o c e s s e s and the mass of P removed by i n o r g a n i c p r e c i p i t a t i o n e s t i m a t e d by measuring the changes i n C a + + c o n c e n t r a t i o n upon r a i s i n g the pH. They found t h a t a l l the P removed by the a e r o b i c p r o c e s s c o u l d be e x p l a i n e d by t h a t r e q u i r e d by the organisms f o r b a s i c m e t a b o l i c purposes, p l u s t h a t removed by c a l c i u m phosphate p r e c i p i t a t i o n . However, the a n o x i c - a e r o b i c p r o c e s s c o n s i s t e n t l y removed s i g n i f i c a n t l y more P i r r e s p e c t i v e of whether the p r o c e s s e s were run a t pH 7.3 o r 6.0. From t h e i r r e s u l t s , Hoffmann and M a r a i s concluded t h a t c h e m i c a l p r e c i p i t a t i o n a c c o u n t e d f o r a r e l a t i v e l y s m a l l f r a c t i o n of P r e m o v a l , a maximum of about 1.5 mg/L. Furt h e r m o r e , i t appeared as i f the presence of the a n o x i c r e a c t o r s t i m u l a t e d e x c e s s b i o l o g i c a l P removal i n some u n e x p l a i n e d -14-manner. In a d d i t i o n to l a b o r a t o r y s c a l e and b a t c h s t u d i e s d u r i n g t h i s p e r i o d , a number of r e l e v a n t s t u d i e s of f u l l s c a l e p l a n t o p e r a t i o n were a l s o r e p o r t e d which l a i d the groundwork f o r u n d e r s t a n d i n g the p r e r e g u i s i t e s f o r e x c e s s b i o l o g i c a l P r e m o v a l . A number of r e s e a r c h workers r e p o r t e d d a t a from f u l l - s c a l e p r o c e s s e s e x h i b i t i n g e x c e s s P r e m o v a l . A l l of these p r o c e s s e s were h i g h r a t e , p l u g f l o w p r o c e s s e s w i t h s h o r t s l u d g e ages i n the 1.5-6 day range. Underflow sludge r e c y c l e r a t e s were i n the 0.25:1-0.5:1 range w i t h r e s p e c t to the i n f l u e n t f l o w . T y p i c a l r e s u l t s of the p e r i o d were p r e s e n t e d by S c a l f e t a l . (1969), who were i n v e s t i g a t i n g the e f f e c t s of a e r a t i o n i n t e n s i t y a t the B l a c k R i v e r Sewage Works i n B a l t i m o r e . D i s s o l v e d oxygen and phosphorus c o n c e n t r a t i o n p r o f i l e s f o r the two semi- p l u g f l o w a e r a t i o n tanks a r e p r e s e n t e d i n F i g . 2.5. A e r a t i o n Tank 2 was a e r a t e d a t a lo w e r r a t e than A e r a t i o n Tank 1 such t h a t i t had oxygen l i m i t i n g c o n d i t i o n s as f a r as the halfway p o i n t a l o n g the tank l e n g t h . The s i g n i f i c a n t d i f f e r e n c e between the P p r o f i l e s i s t h a t A e r a t i o n Tank 2 e x h i b i t e d P r e l e a s e i n the f i r s t q u a r t e r . Phosphorus uptake o c c u r r e d i n the middle h a l f of the p r o c e s s a t a s l i g h t l y h i g h e r r a t e than i n A e r a t i o n Tank 1 so t h a t a l l the P was removed a t a p p r o x i m a t e l y the t h r e e - q u a r t e r p o i n t . T h i s r e l e a s e was thought t o be the r e s u l t of the reduced a e r a t i o n i n t e n s i t y but S c a l f e t a l . a l s o came to t h e e r r o n e o u s c o n c l u s i o n t h a t the reduced a e r a t i o n a l s o l e d to a r e d u c t i o n i n the P uptake r a t e . I t was recommended t h a t i n o r d e r to e n s u r e e x c e s s P re m o v a l , the d i s s o l v e d oxygen c o n c e n t r a t i o n i n the second h a l f of the a e r a t i o n tank be kept between 2 and 5 rag/L. However, M i l b u r y -15-IN l/4Pt. l/2Pt. 3/4Pt. OUT LOCATION IN A E R A T I O N TANK Fig. 2.5. Dissolved oxygen and P concentration p r o f i l e s for two p a r a l l e l aeration tanks exhibiting excess b i o l o g i c a l P removal. Data reported by Scalf et a l . (1969). -16-e t a l . (1970) p o i n t e d out t h a t e x c e s s P removal c o u l d n o t be a c h i e v e d i n a c o m p l e t e l y mixed regime and, t h e r e f o r e , a e r a t i o n i n t e n s i t y a l o n e c o u l d not guarantee e x c e s s P r e m o v a l . C l e a r l y t h e n , the oxygen l i m i t i n g c o n d i t i o n s a t the head end of the p l u g flow p r o c e s s e s p l a y e d some, as y e t u n d e f i n e d , r o l e . The l a c k of an adequate u n d e r s t a n d i n g of the b i o c h e m i c a l b a s i s f o r e x c e s s P removal a t the time i s c l e a r l y i l l u s t r a t e d i n the d e s i g n g u i d e l i n e s f o r e x c e s s b i o l o g i c a l P removal p r o c e s s e s p r e s e n t e d by M i l b u r y e t a l . (1971). T h e i r d e s i g n c r i t e r i a i n c l u d e d recommendations f o r a p l u g f l o w regime, t h a t the feed be i n t r o d u c e d a t the head end of the p r o c e s s , t h a t s u f f i c i e n t a e r a t i o n be s u p p l i e d to the e f f l u e n t end of the p r o c e s s , t h a t n i t r i f i c a t i o n be a v o i d e d , e t c . The r e l e v a n c e of P r e l e a s e a t the head end of the p r o c e s s and i t s p o s s i b l e c o n n e c t i o n w i t h e x c e s s b i o l o g i c a l P removal were not u n d e r s t o o d . Fuhs and Chen (1975) were the f i r s t r e s e a r c h workers to s p e c i f i c a l l y i n v e s t i g a t e the importance of the a n a e r o b i c - a e r o b i c sequence and i t s e f f e c t on the m i c r o b i o l o g i c a l n a t u r e of the s l u d g e . They noted t h a t a m i c r o s c o p i c e x a m i n a t i o n of the s l u d g e from an a n a e r o b i c - a e r o b i c l a b o r a t o r y - s c a l e p r o c e s s t h a t was not removing e x c e s s P r e v e a l e d v e r y few organisms capable of s t o r i n g p o l y p h o s p h a t e . They s u b j e c t e d s l u d g e from two f u l l - s c a l e p l a n t s t h a t were removing e x c e s s P to a 4 hour a e r o b i c / 2 0 hour a n a e r o b i c b a t c h t e s t sequence t h a t had been s p i k e d w i t h raw sewage. I n i t i a l l y , a l l the P was removed a e r o b i c a l l y and r e l e a s e v a l u e s of up t o 4 0 mg/L were noted under a n a e r o b i c c o n d i t i o n s . They -17-c o n f i r m e d the f i n d i n g of W e l l s ( 19 69 ) t h a t i n a b a t c h t e s t s u b j e c t e d t o a number of a n a e r o b i c - a e r o b i c c y c l e s , b o t h the uptake and r e l e a s e of P p r o g r e s s i v e l y d e c r e a s e d to t h e p o i n t t h a t uptake and r e l e a s e f i n a l l y c e a s e d . They a l s o c o n f i r m e d the i n h i b i t o r y e f f e c t s of 2 , 4 - d i n i t r o p h e n o l on a e r o b i c uptake i n a p a r a l l e l b a t c h t e s t . U s i n g a s e r i e s of m i c r o s c o p i c i d e n t i f i c a t i o n t e s t s , they a t t r i b u t e d the a b i l i t y t o s t o r e e x c e s s P t o one s p e c i f i c m o r p h o l o g i c a l b a c t e r i u m type - to organisms b e l o n g i n g t o the A c i n e t o b a c t e r genus. Pure b a t c h c u l t u r e s of A c i n e t o b a c t e r t h a t were f e d w i t h a c e t a t e and s u b j e c t e d t o a n a e r o b i c - a e r o b i c sequences had s i m i l a r P r e l e a s e and uptake p a t t e r n s to the mixed l i q u o r b a t c h t e s t s . Fuhs and Chen reasoned t h a t the a n a e r o b i c - a e r o b i c sequence a l l o w e d A c i n e t o b a c t e r t o f l o u r i s h i n the p r o c e s s because the a n a e r o b i c zone promoted the growth of a f a c u l t a t i v e p o p u l a t i o n , which produced compounds such as e t h a n o l , a c e t a t e and s u c c i n a t e . These i n t e r m e d i a t e s then s e r v e d as the carbon s o u r c e f o r the A c i n e t o b a c t e r , a r e l a t i v e l y slow growing o b l i g a t e a e r o b e . T h i s t h e o r y d i d n o t , however, e x p l a i n why A c i n e t o b a c t e r grew p r e f e r e n t i a l l y i n an a n a e r o b i c - a e r o b i c system and d i d not f l o u r i s h i n a p u r e l y a e r o b i c system to which the above-mentioned i n t e r m e d i a t e s were added. Furthermore, i t d i d not e x p l a i n the r e l e a s e of P i n the a n a e r o b i c zone o r whether t h i s was i n any way r e l a t e d t o the e x c e s s b i o l o g i c a l P r e m o v a l . F u r t h e r i n c o n s i s t e n c i e s i n the A c i n e t o b a c t e r h y p o t h e s i s w i l l be d e a l t w i t h l a t e r i n t h i s r e v i e w . However, the t h e o r y of Fuhs and Chen was s i g n i f i c a n t i n t h a t i t r e p r e s e n t e d the f i r s t m i c r o b i o l o g i c a l -18-b a s i s f o r why e x c e s s b i o l o g i c a l P r e m o v a l was promoted i n a p r o c e s s h a v i n g an a n a e r o b i c - a e r o b i c s e q u e n c e . The f i r s t r e s e a r c h e r t o p r o p o s e t h a t a n a e r o b i c P r e l e a s e i s a n i n t r i n s i c p a r t of t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism was B a r n a r d ( 1 9 7 6 ) . W h i l e i n v e s t i g a t i n g t h e Bardenpho f o u r - r e a c t o r n i t r i f i c a t i o n - d e n i t r i f i c a t i o n p r o c e s s ( F i g . 2 . 6 ) , he n o t e d t h a t e x c e s s i v e P r e l e a s e t o a c o n c e n t r a t i o n o f a b o u t 3 0 mg/L i n t h e s e c o n d a r y a n o x i c r e a c t o r o c c u r r e d . T h i s was f o l l o w e d by v i r t u a l c o m p l e t e u p t a k e i n the r e a e r a t i o n r e a c t o r , r e s u l t i n g i n e x c e s s P r e m o v a l by the p r o c e s s . He p o i n t e d o u t t h a t t h e common f e a t u r e between t h i s p r o c e s s and p l u g f l o w h i g h - r a t e p r o c e s s e s r e p o r t e d i n the l i t e r a t u r e t o a l s o e x h i b i t e x c e s s P r e m o v a l , was the s i g n i f i c a n t P r e l e a s e i n an a n a e r o b i c zone o f t h e p r o c e s s . F u r t h e r m o r e , he s t a t e d t h a t i n o r d e r t o r e l i a b l y i n d u c e e x c e s s b i o l o g i c a l P r e m o v a l , the mixed l i q u o r s h o u l d be s u b j e c t e d : t o a n a n a e r o b i c s t a t e o f s u c h i n t e n s i t y t h a t P r e l e a s e o c c u r s , and t h a t P r e l e a s e was the r e s u l t of a minimum l e v e l o f o x i d a t i o n -r e d u c t i o n p o t e n t i a l (ORP) h a v i n g been a t t a i n e d . He p o i n t e d t o the r e p o r t e d d i f f i c u l t i e s of m e a s u r i n g ORP i n mixed l i q u o r and s u g g e s t e d t h a t P r e l e a s e would be a more e a s i l y m e a s u r a b l e p a r a m e t e r i n d i c a t i n g t h a t a s u f f i c i e n t l y low ORP had been a t t a i n e d . To t h i s end he s u g g e s t e d a m o d i f i c a t i o n o f t h e Bardenpho p r o c e s s w h i c h i n c l u d e d a n a n a e r o b i c zone a t the head end o f the p r o c e s s t h a t r e c e i v e d b o t h t h e s l u d g e r e c y c l e and t h e i n f l u e n t s t r e a m . T h i s p r o c e s s became known a s t h e M o d i f i e d Bardenpho o r Phoredox p r o c e s s ( F i g . 2 . 7 ) . B a r n a r d a l s o drew a t t e n t i o n t o the a d v e r s e e f f e c t t h a t n i t r a t e e n t e r i n g t h e - 1 9 -PRIMARY SECONDARY ANOXIC AEROBIC ANOXIC REACTOR REACTOR REACTOR R E A E R A T I O N MIXED LIQUOR RECYCLE R E A C T O R F i g . 2.6. 4-stage Bardenpho n i t r i f i c a t i o n -d e n i t r i f i c a t i o n process configuration. PRIMARY AEROBIC SECONDARY ANOXIC REACTOR ANOXIC REACTOR REACTOR MIXED L IQUOR RECYCLE REAERATION F i g . 2.7. Phoredox or Modified Bardenpho Process configuration for b i o l o g i c a l nitrogen and phosphorus removal. ANAEROBIC ANOXIC AEROBIC REACTOR REACTOR REACTOR RECYCLE MIXED LIQUOR SLUDGE RECYCLE s F i g . 2.8. UCT Process configuration for b i o l o g i c a l nitrogen and phosphorus removal. -20-a n a e r o b i c zone would have on a c h i e v i n g the r e g u i r e d minimum l e v e l of ORP o r a n a e r o b i c s t r e s s . The n e g a t i v e e f f e c t of n i t r a t e e n t e r i n g the a n a e r o b i c zone of the Bardenpho-type p r o c e s s e s was f u r t h e r i n v e s t i g a t e d by o t h e r r e s e a r c h e r s (McLaren and Wood, 1976, and N i c o l l s , 19 78) and m i n i m i z i n g i t s e f f e c t proved to be a major c h a l l e n g e i n the development of the combined n i t r i f i c a t i o n -d e n i t r i f i c a t i o n P removal p r o c e s s . These s t u d i e s c o n f i r m e d t h a t P r e l e a s e was c o - i n c i d e n t w i t h e x c e s s P removal and t h a t t h i s r e l e a s e was most l i k e l y t o o c c u r i n the a n a e r o b i c zone a t the head end of the p r o c e s s . N i c h o l l s and Osborn ( 1979) developed a b i o c h e m i c a l model t o e x p l a i n e x c e s s P removal which extended the h y p o t h e s i s of H a r o l d ( 1966), t h a t p o l y - P a c c u m u l a t i o n was a consequence of the organisms b e i n g s u b j e c t e d to a n a e r o b i c s t r e s s . They m a i n t a i n e d t h a t the a b i l i t y to s t o r e carbon i n the form of p o l y - B -h y d r o x y b u t y r a t e (PHB) p l a y e d an i m p o r t a n t r o l e i n the s u r v i v a l of a e r o b i c organisms i n the a n a e r o b i c zone. B r i e f l y , organisms c o u l d s t o r e e x c e s s H + i o n s produced i n the o x i d a t i o n of sewage s u b s t r a t e to p y r u v i c a c i d i n the form of w a t e r i n s o l u b l e PHB u n t i l the onset of a e r o b i c c o n d i t i o n s where the i o n s would be r e l e a s e d as water i n the a e r o b i c Krebs (TCA) c y c l e . T h e i r model i m p l i c a t e d two s u r v i v a l mechanisms: 1) The energy f o r ATP f o r m a t i o n i s d e r i v e d from the breakup of p o l y - P c h a i n i n the r e l e a s e of P; and 2) t h a t the f o r m a t i o n of PHB a c t s as a s i n k f o r e x c e s s H + i o n s and e l e c t r o n s . An i m p o r t a n t recommendation of the r e s e a r c h group was the p o t e n t i a l b e n e f i t of the a d d i t i o n of s h o r t -21-chain vo la t i l e f a tty acids (VFA's), as found i n digester supernatant, to the anaerobic zone of the process, since these acids are the preferred substrates for carbon storage. In spite of the fact that a number of f u l l - s c a l e Pho redox processes were being designed and constructed, with the majority of these in South A f r i c a , problems with i t s basic design concept began to emerge. Simpkins and McLaren ( 1978) found the d e n i t r i f i c a t i o n rates i n the secondary anoxic zone to be s i g n i f i c a n t l y lower than in the primary anoxic zone and suggested that i t , and the re-aeration zone, be omitted and the primary anoxic zone correspondingly enlarged. A l l studies into the Bardenpho and Phoredox processes confirmed Barnard's findings with regard to the detrimental effect of n i t r a t e entering the anaerobic zone on P release and excess P removal. More s p e c i f i c a l l y , once a p a r t i c u l a r configuration has been chosen, the mass of n i t r a t e entering the anaerobic zone (the concentration i n the sludge recycle being equal to that i n the effluent) i s largely a function of the influent sewage cha r a c t e r i s t i c s , mainly the COD and TKN concentrations. Because n i t r i f i c a t i o n i s usually complete in these processes, and the denitr i f i c ation capacity i s largely a function of the influent COD and the process configuration, any increase i n the influent TKN generally re s u l t s i n a corresponding increase i n the effluent n i t r a t e concentration and, therefore, the mass of n i t r a t e being recycled to the anaerobic zone. During the period 1974-1982, an extensive research program into -22-the n i t r i f i c a t i o n - d e n i t r i f i c a t i o n kinetics of the activated sludge process was carried out at the University of Cape Town. This led to the development of a k i n e t i c model that allowed the determination of both the n i t r i f i c a t i o n and d e n i t r i f i c a t i o n capacities of a p a r t i c u l a r process, and accurately predicted the COD, TKN and nitr a t e concentrations at any point in the process (Nicholls, 1982). Because the int e r r e l a t i o n s h i p between the n i t r i f i c a t i o n - d e n i t r i f i c a t i o n kinetics and the excess b i o l o g i c a l P removal mechanism were being more c l e a r l y understood, the development of this model proved to be instrumental i n the further development of the b i o l o g i c a l P removal process. B r i e f l y , van Haandel et a l . (1981) and Dold et a l . (1980) determined that the biodegradable f r a c t i o n of the influent COD i s made up of two d i s t i n c t components, each having a profoundly d i f f e r e n t e f f e c t on the de ni tr i f ica tion kinetics of the process. These fractions are a readily biodegradable f r a c t i o n which i s rapidly u t i l i z e d in the denitr i f i c ation reaction, and a particulate component that requires enzymatic breakdown p r i o r to metabolism, and re s u l t s in a s i g n i f i c a n t l y lower rate of denitr i f i c ation (that i s temperature dependent). I t thus became possible, on this basis, to determine the de ni tr i f ica tion capacity of the anaerobic and anoxic reactors i n terms of the reactor size, process configuration and influent COD c h a r a c t e r i s t i c s . Working on the assumption that redox potential measurement was d i f f i c u l t in activated sludge (Barnard, 19 76) and did not quantify the anaerobic stress required for P release (Randall et -23-a l . , 1970), R a b i n o w i t z and M a r a i s ( 1980) sought an a l t e r n a t i v e parameter to q u a n t i f y a n a e r o b i c s t r e s s t h a t was based on the n i t r i f i c a t i o n - d e n i t r i f i c a t i o n k i n e t i c model. The parameter, known as the a n a e r o b i c p o t e n t i a l , was d e f i n e d as the d i f f e r e n c e between the d e n i t r i f i c a t i o n c a p a c i t y of the a n a e r o b i c r e a c t o r and the mass of n i t r a t e e n t e r i n g the r e a c t o r ( b o t h expressed as mg tsl p e r l i t r e of i n f l u e n t ) . F u r t h e r m o r e , they suggested a m o d i f i c a t i o n t o the Phoredox p r o c e s s t h a t would ensure t h a t no n i t r a t e e n t e r e d the a n a e r o b i c zone. The s l u d g e r e c y c l e and t h e mixed l i q u o r r e c y c l e were d i s c h a r g e d i n t o the a n o x i c r e a c t o r , and mixed l i q u o r was passed from the a n o x i c r e a c t o r to the a n a e r o b i c r e a c t o r v i a an a d d i t i o n a l r e c y c l e . The c o n f i g u r a t i o n became known as the UCT p r o c e s s ( F i g . 2.8). By a d j u s t i n g the r e c y c l e r a t e from the a e r o b i c to t h e a n o x i c r e a c t o r , the n i t r a t e c o n c e n t r a t i o n i n the a n o x i c r e a c t o r c o u l d be m a i n t a i n e d a t a low o r z e r o c o n c e n t r a t i o n and the d e t r i m e n t a l e f f e c t of n i t r a t e e n t e r i n g the a n a e r o b i c zone c o u l d , t h e r e f o r e , be e l i m i n a t e d . Thus the UCT p r o c e s s would be more f l e x i b l e i n o p e r a t i o n than the Bardenpho o r Phoredox c o n f i g u r a t i o n s , p a r t i c u l a r l y i n t r e a t i n g wastes w i t h h i g h TKN/COD r a t i o s . T h e r e f o r e , i t was more l i k e l y to s u b j e c t the sludge to t h e r e q u i r e d degree of a n a e r o b i c s t r e s s f o r the e x c e s s b i o l o g i c a l P removal mechanism to o p e r a t e . U s i n g the concept of a n a e r o b i c p o t e n t i a l , R a b i n o w i t z and M a r a i s a n a l y s e d the d a t a f o r l a b o r a t o r y s c a l e M o d i f i e d Phoredox ( i . e . having no secondary a n o x i c zone) and UCT p r o c e s s e s and found t h a t i n o r d e r to a c h i e v e a n a e r o b i c P r e l e a s e and e x c e s s b i o l o g i c a l P removal, the d e n i t r i f i c a t i o n c a p a c i t y of the a n a e r o b i c zone must -24-exceed the mass of n i t r a t e e n t e r i n g the r e a c t o r by a t l e a s t 9 mg N/L. S i e b r i t z e t a l . ( 1980 , 19 83 ) c a r r i e d out an e x t e n s i v e s e r i e s of i n v e s t i g a t i o n s i n t o the a p p l i c a b i l i t y of the a n a e r o b i c p o t e n t i a l h y p o t h e s i s f o r the UCT, M o d i f i e d Phoredox and L u d z a k - E t t i n g e r p r o c e s s c o n f i g u r a t i o n s . They found t h a t a UCT p r o c e s s , w i t h a 7.5% a n a e r o b i c mass f r a c t i o n , had an a n a e r o b i c p o t e n t i a l of 12 mg N/L and e x h i b i t e d P r e l e a s e and system e x c e s s b i o l o g i c a l P r e m o v a l . However, a p a r a l l e l a n o x i c - a e r o b i c ( L u d z a k - E t t i n g e r ) p r o c e s s , w i t h an u n a e r a t e d s l u d g e mass f r a c t i o n of 7 0% and an a n a e r o b i c p o t e n t i a l of 3 4 mg N/L, f a i l e d to r e l e a s e P and e x h i b i t e d o n l y m inimal system P r e m o v a l . On a p p l i c a t i o n of the UCT k i n e t i c model f o r n i t r i f i c a t i o n and d e n i t r i f i c a t i o n , a fundamental d i f f e r e n c e between the two p r o c e s s e s was r e v e a l e d w i t h r e g a r d to the s u b s t r a t e u t i l i z a t i o n c h a r a c t e r i s t i c s . I n the UCT p r o c e s s most of the d e n i t r i f i c a t i o n c a p a c i t y of the a n a e r o b i c r e a c t o r was d e r i v e d from the a v a i l a b i l i t y of r e a d i l y b i o d e g r a d a b l e COD i n the i n f l u e n t , none of which i s f o r the d e n i t r i f i c a t i o n of n i t r a t e e n t e r i n g the r e a c t o r . I n the M o d i f i e d L u d z a k - E t t i n g e r p r o c e s s , a l l of the r e a d i l y b i o d e g r a d a b l e COD e n t e r i n g the u n a e r a t e d zone i s o f t e n o x i d i z e d by the n i t r a t e e n t e r i n g the r e a c t o r v i a the sludge and i n t e r n a l r e c y c l e s . The h i g h d e n i t r i f i c a t i o n c a p a c i t y and the r e s u l t i n g h i g h a n a e r o b i c p o t e n t i a l of the L u t z a k - E t t i n g e r p r o c e s s i s , t h e r e f o r e , d e r i v e d from the i n o r d i n a t e l y l a r g e de n i t r i f i c a t i o n r e a c t o r and the s l o w l y b i o d e g r a d a b l e COD component t h e r e i n . -25-As a r e s u l t of t h i s breakdown i n t h e a n a e r o b i c p o t e n t i a l h y p o t h e s i s , S i e b r i t z e t a l . ( 1982 , 19 83) r e d e f i n e d t h e p r e r e q u i s i t e s f o r e x c e s s b i o l o g i c a l P r e m o v a l i n terms o f t h e c o n c e n t r a t i o n o f r e a d i l y b i o d e g r a d a b l e COD a v a i l a b l e to t h e o r g a n i s m s i n the a n a e r o b i c r e a c t o r . Upon the a p p l i c a t i o n o f s t a t i s t i c a l a n a l y s i s t o d a t a a v a i l a b l e f o r a number of p r o c e s s c o n f i g u r a t i o n s , t h e y f o u n d t h a t a n a e r o b i c P r e l e a s e o c c u r r e d when th e r e a d i l y b i o d e g r a d a b l e s u b s t r a t e (RBS) c o n c e n t r a t i o n e n t e r i n g t h e a n a e r o b i c r e a c t o r was g r e a t e r t h a n 25 mg COD/L. F u r t h e r m o r e , the mass o f P r e l e a s e d i n c r e a s e d a s t h e RBS c o n c e n t r a t i o n e n t e r i n g t h e a n a e r o b i c r e a c t o r i n c r e a s e d above 25 mg/L. T h i s new model c l e a r l y d e m o n s t r a t e d t h e r e a s o n why t h e B a r d e n p h o - t y p e p r o c e s s c o n f i g u r a t i o n s were n o t o p t i m a l f o r e x c e s s b i o l o g i c a l P r e m o v a l , p a r t i c u l a r l y f o r p r o c e s s e s t r e a t i n g w a s t e s t r e a m s w i t h a TKN/COD of g r e a t e r t h a n a b o u t 0.08. A t t h e h i g h e r TKN/COD r a t i o s t h e c o n c e n t r a t i o n o f n i t r a t e e n t e r i n g t h e a n a e r o b i c r e a c t o r c a n become i n o r d i n a t e l y l a r g e a n d b e c a u s e e a c h mg o f n i t r a t e ( a s N) r e s u l t s i n the o x i d a t i o n o f 8.6 mg of RBS ( a s COD) ( v a n H a a n d e l e t a l . , 1981), an RBS c o n c e n t r a t i o n o f 25 mg/L b e i n g a v a i l a b l e t o t h e o r g a n i s m s i n the a n a e r o b i c r e a c t o r becomes i m p o s s i b l e . P r o c e s s c o n f i g u r a t i o n s s u c h a s t h e UCT p r o c e s s , which make i t p o s s i b l e t o g u a r a n t e e a z e r o n i t r a t e d i s c h a r g e t o t h e a n a e r o b i c z one, a r e t h e r e f o r e a t a s i g n i f i c a n t a d v a n t a g e . A f u r t h e r c o n s e q u e n c e of t h i s model i s t h a t w a s t e w a t e r s h a v i n g a t o t a l COD c o n c e n t r a t i o n o f l e s s t h a n 250 mg/L a r e n o t amenable to i n d u c i n g e x c e s s b i o l o g i c a l P r e m o v a l , a s o n l y a b o u t 2 0% o f t h i s COD i s i n a r e a d i l y b i o d e g r a d a b l e form and i t g e t s d i l u t e d by t h e s l u d g e -26-r e c y c l e e n t e r i n g t h e a n a e r o b i c r e a c t o r . S i e b r i t z e t a l . d e m o n s t r a t e d the e f f e c t s of i n c r e a s i n g t h e r e a d i l y b i o d e g r a d a b l e COD c o n c e n t r a t i o n of the i n f l u e n t to a l a b o r a t o r y - s c a l e UCT p r o c e s s (See F i g . 2 . 9 ) . The t o t a l i n f l u e n t COD was c o n t r o l l e d a t 800 mg/L b u t d u r i n g t h e e x p e r i m e n t a l p e r i o d , i n w h i c h t h e r e a d i l y b i o d e g r a d a b l e component was i n c r e a s e d from a b o u t 120 to 2 20 mg COD/L by t h e a d d i t i o n of a c e t a t e , a s i g n i f i c a n t improvement i n t h e s y s t e m P r e m o v a l was a c h i e v e d . R e n s i n k (1981) e x t e n d e d t h e h y p o t h e s i s o f O s b o r n and N i c h o l l s t o e x p l a i n how the p r e s e n c e of a n a n a e r o b i c z o n e f a v o u r s the p r o l i f e r a t i o n of p o l y - P s t o r i n g o r g a n i s m s . He h y p o t h e s i z e d t h a t t h e o r g a n i s m s s t o r e d c a r b o n d e r i v e d from s h o r t c h a i n VFA's u n d e r a n a e r o b i c c o n d i t i o n s i n the form o f PHB. The e n e r g y f o r PHB f o r m a t i o n i s g e n e r a t e d from breakdown of p o l y - P t o h y d r o l i z e d o r t h o - P , i . e . by P r e l e a s e . Upon e n t e r i n g t h e a e r o b i c z o n e , p o l y - P - s t o r i n g o r g a n i s m s w o u l d have an a d v a n t a g e o v e r o t h e r o r g a n i s m s i n t h e form o f t h i s s t o r e d c a r b o n e v e n i f t h e i r g r o w t h r a t e s a r e l o w e r , a s i n the c a s e of A c i n e t o b a c t e r . An i m p o r t a n t a s p e c t of R e n s i n k ' s h y p o t h e s i s i s the r o l e o f s t o r e d p o l y - P i n the s t o r a g e o f c a r b o n u n d e r a n a e r o b i c c o n d i t i o n s . T h i s was d e m o n s t r a t e d a s f o l l o w s : He c o n v e r t e d a 10 r e a c t o r - i n - s e r i e s a e r o b i c p r o c e s s t o a 5 a n a e r o b i c / 5 a e r o b i c r e a c t o r s e r i e s and added p e r i o d i c d o s a g e s of a c e t a t e . I n i t i a l l y , t h e r e was no P r e l e a s e o r e x c e s s u p t a k e and v e r y l i t t l e a c e t a t e d i s a p p e a r a n c e from t h e s u p e r n a t a n t i n the a n a e r o b i c zone (See F i g . 2.10). However, a f t e r a s i x week p e r i o d , t h e added a c e t a t e d i s a p p e a r e d by the time t h e p l u g f l o w r e a c h e d t h e t h i r d a n a e r o b i c r e a c t o r and -27-_ J 0 0 0 O 800 ^ T O O -§ 600 CO O 500 z o 4 0 0 -o a o o 300 2 0 0 -100? C O D Arrows indicate new wastewater batches t l i l i 1 10 20 30 40 50 DAY O F OPERATION -40 100 CO 80 £ CO 20 ^ CO tr o x a. co o x 0-— Predicted removal - A - Meosured removal 10 20 30 40 50 DAY OF O P E R A T I O N 60 F i g . 2.9. R e s u l t s from a l a b o r a t o r y - s c a l e UCT pr o c e s s showing the e f f e c t of i n c r e a s i n g the c o n c e n t r a t i o n of r e a d i l y biodegradable COD i n the i n f l u e n t ( S D S ^ ) . Sludge age = 20 days; Temp. = 20 °C. Data r e p o r t e d by S i e b r i t z ' e t a l . (1983). -28-C7> 8 0 70 6 0 5 0 ^ 4 0 o 3 0 o 2 0 10 0 8 0 _ 6 0 cn E U J 4 0 l -u o < ige load ings ^400gC0D/kg sludge. Flow = IOOL/h MLSS=2500mg/l. Temp.= l4°C o -o-—-o-o-—-cr I I 2 3 4 5 6 7 8 9 10 E R E A C T O R NUMBER 2 0 Init ia l Per iod Af ter 6 weeks J I 1 2 3 4 5 R E A C T O R NUMBER Fig. 2.10. (Top) Results of a 10 reactor-in-series anaerobic/aerobic process showing P, Ca, and Mg p r o f i l e s . (Bottom) Acetate p r o f i l e s in the anaero-bic zone immediately a f t e r conversion from a purely aerobic process and a f t e r six weeks of acetate addition. Data reported by Rensink (1981) . -29-P release and system excess P removal took place. A microscopic examination revealed a s i g n i f i c a n t increase in the number of poly-P organisms in the sludge. In this way, Rensink demonstrated that anaerobic acetate removal and P release are associated with the presence of poly-P organisms. In contrast to the readily biodegradable COD hypothesis of S i e b r i t z et al ., in which the preferred substrates are present in the incoming waste stream, Rensink maintained that the presence of short chain VFA's in the anaerobic reactor was the result of VFA production by facultative organisms and a consequence of a s u f f i c i e n t l y low redox potential being attained. This aspect of his hypothesis i s s t i l l currently being investigated. Perhaps the most important contribution of S i e b r i t z et a l . and Rensink towards the understanding of the excess P removal mechanism was the s h i f t in emphasis away from the degree of anaerobic stress to the significance of the presence of preferred substrates in the anaerobic zone of the process. This contribution has been invaluable i n the development of a r e l i a b l e design strategy for processes i n which excess b i o l o g i c a l P removal i s to be guaranteed, as i t c l a r i f i e d much about the nature of the excess b i o l o g i c a l P removal mechanism. Once the basic hypothesis of the role of s p e c i f i c substrates i n inducing excess b i o l o g i c a l P removal was developed, researchers then began focusing attention on developing a biochemically based model of the mechanism. Fukase et a l . ( 1982 ) conducted a series of laboratory scale " f i l l and draw" and continuous flow -30-experiments using synthetic sewages made up of glucose and acetate. They found that carbon was stored by the organisms under anaerobic conditions in the form of glycogen when glucose was used as the feed, and as PHB when acetate was fed. They also found the P release was concomitant with the disappearance of substrate from solution with molar ratios being AGlucose/AP04 = ^ and AAcetate/APC>4 = 1. Dry weight percent P content of the sludge values as high as 12.8% were measured i n the aerobic zone of the laboratory-scale unit being fed with acetate. Measurement of poly-P showed that with sludge containing 7.23% P, 75% of i t was in the poly-P form, while with sludge containing 5.43% P, only 35% of i t was poly-P. This suggests that the additional P taken up by the sludge was a l l present in the organisms in the form of stored poly-P. Thus far, this section has dealt with a b r i e f overview of the history of excess b i o l o g i c a l P removal, tracing the development of the biochemical model and process design, up u n t i l the onset of this research project. During the course of thi s study, a number of p a r a l l e l research projects were in progress at the University of B r i t i s h Columbia and in other parts of the world that are relevant to the findings of this project. For these reasons, the results of some of these studies w i l l be dealt with in the Discussion Chapter of this thesis. 2.2. V o l a t i l e Fatty Acid (VFA) Production by Primary Sludge Fermentation The concept of maximizing VFA production by fermentation or digestion i s a r e l a t i v e l y new one in wastewater treatment. The -31-v a s t m a j o r i t y of r e s e a r c h i n t o a n a e r o b i c s l u d g e d i g e s t i o n f o c u s e s on methane p r o d u c t i o n , where VFA's s e r v e as the i n t e r m e d i a t e p r o d u c t s , i . e . as s u b s t r a t e f o r the methane f o r m e r s . In the case of methane p r o d u c t i o n , t h e r e f o r e , the b a s i c o b j e c t i v e i s to minimize the VFA c o n c e n t r a t i o n i n the d i g e s t e r f i n a l e f f l u e n t , thereby m a x i m i z i n g methane p r o d u c t i o n . However, t h e r e are a number of r e s e a r c h p r o j e c t s c i t e d i n the l i t e r a t u r e , i n which an attempt was made to s e p a r a t e out the a c i d and methane forming phases of a n a e r o b i c d i g e s t i o n , which o f f e r v i t a l c l u e s to maximizin g VFA p r o d u c t i o n . J e r i s and McCarty ( 1965) found a c e t a t e t o be an i m p o r t a n t i n t e r m e d i a t e f e r m e n t a t i o n p r o d u c t , a c c o u n t i n g f o r o v e r 70 p e r cent of the t o t a l methane produced d u r i n g a n a e r o b i c s l u d g e d i g e s t i o n . McCarty e t a l . ( 1963) p o i n t e d to p r o p i o n a t e as an im p o r t a n t secondary i n t e r m e d i a t e i n the f e r m e n t a t i o n r e a c t i o n . Andrews and Pearson (1965) conducted an i m p o r t a n t s e r i e s of l a b o r a t o r y s c a l e e x p e r i m e n t s on a n a e r o b i c f e r m e n t a t i o n a t 37°C. A s e r i e s of c o m p l e t e l y mixed, c o n t i n u o u s f l o w r e a c t o r s , w i t h mean r e s i d e n c e t i m e s r a n g i n g from 0.75 to 2 2.5 days was run u s i n g a s o l u b l e s y n t h e t i c s u b s t r a t e made up of b o t h o r g a n i c and i n o r g a n i c m a t e r i a l . The range of r e s i d e n c e t i m e s used i n c l u d e d e x p e r i m e n t s i n which b o t h a c i d and methane predominated a s the f i n a l p r o d u c t of the d i g e s t i o n p r o c e s s . T h e i r r e s u l t s a r e p l o t t e d i n F i g . 2.11 w i t h the v a r i o u s e f f l u e n t carbonaceous f r a c t i o n s b e i n g e x p r e s s e d as a f u n c t i o n of the i n f l u e n t t o t a l carbon c o n c e n t r a t i o n . Note t h a t the maximum VFA c o n c e n t r a t i o n i n the system o c c u r r e d a t sludge ages between 2.5 and 4.5 days, w i t h gas p r o d u c t i o n -32-0 2 4 6 8 10 12 14 16 18 20 22 24 RESIDENCE TIME ( days) Fig. 2.11. The eff e c t of batch reactor residence time on effluent carbon d i s t r i b u t i o n . Data reported by Andrews and Pearson (1965). 0 2 4 6 8 10 12 14 16 18 20 22 24 RESIDENCE TIME ( days) F i g . 2.12. Effluent VFA d i s t r i b u t i o n as a function of sludge age. Data reported by Andrews and Pearson ( 1965). -33-(methane and carbon dioxide) predominating at the longer residence times. They attributed the gas production at the short residence times to not being able to completely separate the two phases because of the low generation times of some species of methanogenic bacteria. From the graph of the d i s t r i b u t i o n of the various VFA's presented i n Fig . 2.12 i t can be seen that acetic and propionic acid represent the vast majority of the VFA produced. Furthermore, i t should also be noted that s i g n i f i c a n t l y lower acetic acid concentrations at residence times greater that 5 days c l e a r l y demonstrate acetic acid to be the major intermediate for methane production. Although Andrews and Pearson ( 1965) did not use primary sewage sludge i n their experimentation, their work demonstrated the important p r i n c i p l e that an anaerobic fermenter could be operated and optimized for VFA production using mean hydraulic residence time (or sludge age) as the main process control parameter. Chynoweth and Man (1970) present values reported by several investigators for the composition of raw sewage sludge for the three major classes of organic compounds: carbohydrates, l i p i d s and proteins. A l l three occurred in roughly equal proportions with carbohydrates averaging 35.5%, and l i p i d s and proteins each comprising about 28% of the t o t a l organic compounds present. Data i s also presented regarding the decomposition of the three classes of compounds during the fermentation process. Carbohydrates were decomposed only by about 13%, proteins by about 36% and l i p i d s by about 7 6%. This suggests that l i p i d s are the most important substrate in fermentation, due to th e i r high -3 4 -degree of degradabili ty. Chynoweth and Mah conducted a series of anaerobic batch studies at 35°C with raw sewage sludge and analysed samples for VFA concentration at 1 hour i n t e r v a l s . Their results are presented in F i g . 2.13 and indicate that acetate i s the p r i n c i p l e fermentation product with optimal acetate production occurring a f t e r only 4 hours. They att r i b u t e the decrease in acetate concentration a f t e r about 4 hours to the rate of acetate d i s s i m i l a t i o n due to methanogenesis exceeding i t s production. Gosh et a l . (1975) developed a two-phase anaerobic digestion process consisting of two separate, completely mixed reactors i n series, one for acid fermentation and the other for methane fermentation. From the schematic diagram of the process presented in Fig. 2.14 i t can be seen that each phase of the process has i t s own reactor size and sludge recycle based on growth kinetic requirements for each group of organisms. Gosh et a l . found that i t was possible to separate out and optimize the two phases of the digestion process by "manipulation of d i l u t i o n rate and imposition of l i m i t s on the microbial generation time" i.e. by controlling the hydraulic retention time and sludge age. With regard to acid fermentation, they found that under mesophilic conditions, acidogenesis occurs at pH 5.7, with an ORP of -240 mV ( E c ) and that the v o l a t i l e f r a c t i o n of the sludge serves as the major substrate for the acid formers. The maximum sp e c i f i c growth rate for acid formers was 0.16/day @ 3 5 °C and the loading rates and retention times varied between 1.33 to 3.34 g/hr/L and 10 to 2 4 hours respectively. -35-T I M E ( h o u r s ) Fig. 2.13. VFA production by primary sludge fermentation a t 35 C. Data re-ported by Chynoweth and Man (1970). Fig . 2.14. Schematic diagram of a two-phase anaerobic digestor with separation of the acid and methane producing phases by hydraulic c o n t r o l . After Gosh et a l . (1975). -36-Although the l i t e r a t u r e c i t e d above deals with experimentation carried out in the mesophilic temperature range ( i . e . at temperatures around 37°C), i t demonstrates some important p r i n c i p l e s regarding acid fermentation in general. F i r s t l y , that i t i s possible to optimize the operation of a primary sludge fermenter for acid production by hydraulic control of the sludge age. Secondly, that the growth rates of acid formers i n the 14-22°c temperature range i s l i k e l y to be s i g n i f i c a n t l y lower than in the mesophillic temperature range. Thirdly, that very l i t t l e i s known about the eff e c t of pH on VFA production but i t might be possible to operate an acid fermenter at an uncontrolled pH in the range 5.5-6.0. It i s clear, therefore, that because the concept of VFA production by primary sludge fermentation for use as a substrate in the activated sludge process i s a r e l a t i v e l y new one, knowledge of fermenter design and operation for VFA production i s lacking, in p a r t i c u l a r the e f f e c t s of sludge age, temperature and pH. -37-CHAPTER THREE EXPERIMENTAL METHODS The e x p e r i m e n t a l methods used i n t h i s r e s e a r c h a r e o u t l i n e d i n d e t a i l i n t h i s c h a p t e r . S e c t i o n 3.1 d e a l s w i t h the a n a l y t i c a l methods used on a l l s a m p l e s a n a l y s e d and measurements t a k e n . E x p e r i m e n t a l p r o c e d u r e s f o r the b a t c h t e s t i n g and p i l o t s c a l e o p e r a t i o n a r e o u t l i n e d i n S e c t i o n s 3.2 and 3.3, r e s p e c t i v e l y . 3.1. A n a l y t i c a l Methods C h e m i c a l Oxygen Demand (COD) a n a l y s i s was done i n a c c o r d a n c e w i t h S t a n d a r d Methods ( 15th E d . , A.P.H.A., 19 80) . O r t h o - P a n a l y s i s was done u s i n g the s t a n n u o u s c h l o r i d e t e c h n i q u e a l s o o u t l i n e d i n S t a n d a r d Methods. In c a s e s where a l a r g e number o f samples were g e n e r a t e d i n a s h o r t s p a c e of t i m e , ( e . g . d u r i n g a b a t c h t e s t ) , o r t h o - P a n a l y s i s was done by t h e automated a s c o r b i c a c i d r e d u c t i o n method on a A u t o A n a l y s e r Model I I ( T e c h n i c o n , 1 9 7 3 a ) . T o t a l K j e l d a h l N i t r o g e n (TKN) and t o t a l P s a m p l e s were s u b j e c t e d t o a c i d d i g e s t i o n and a n a l y s e d o n the Auto A n a l y s e r . The d i g e s t i o n method us e d i s f u l l y d e s c r i b e d i n t h e b l o c k d i g e s t e r i n s t r u c t i o n manual ( T e c h n i c o n , 19 7 4 ) . The d r y w e i g h t p e r c e n t P c o n t e n t o f the s l u d g e was done by w e i g h i n g o u t a g i v e n mass o f oven d r i e d s l u d g e (104°C) and s u b j e c t i n g i t t o a c i d d i g e s t i o n and t o t a l P a n a l y s i s a s d e s c r i b e d a b o v e . T h i s method was t e s t e d i n an a n a e r o b i c / a e r o b i c s e q u e n c e b a t c h t e s t where the P r e l e a s e and s u b s e q u e n t u p t a k e were a b o u t 4 0 mg/L. The c h a n g e s i n t h e p e r c e n t P c o n t e n t of the s l u d g e were measured a t c r i t i c a l time i n t e r v a l s and f o u n d t o a c c o u n t f o r a l l o f t h e P r e l e a s e d t o a n d t a k e n up -38-from the s u p e r n a t a n t . N i t r a t e and n i t r i t e a n a l y s e s were done u s i n g a copper-cadmium column i n which n i t r a t e was reduced to n i t r i t e , f o l l o w e d by c o l o r m e t r i c measurement of the n i t r i t e on the Auto A n a l y s e r ( T e c h n i c o n , 19 73b). T o t a l F i l t e r a b l e S o l i d s (TFS) a n a l y s i s was done by vacuum f i l t e r i n g a known volume of sample through a pre-washed 5.5 cm d i a m e t e r Reeve-Angel o r Whatman 934-AH g l a s s f i b r e f i l t e r and oven d r y i n g i t f o r 1 hour a t 104°C. T h i s method i s an a d a p t a t i o n of the c r u c i b l e method f o r d e t e r m i n i n g the T o t a l Suspended S o l i d s (TSS) o u t l i n e d i n S tandard Methods, and i t produced comparable r e s u l t s . V o l a t i l e F a t t y A c i d (VFA) a n a l y s i s was done u s i n g a H e w l e t t -P a c k a r d 5880A Gas Chromatograph equipped w i t h a flame i o n i z a t i o n d e t e c t o r (F.I.D.) and u s i n g n i t r o g e n as the c a r r i e r gas. The G.C. was f i t t e d w i t h a 0.91 m l o n g , 6 mm O.D. and 3 mm l . D . g l a s s column packed w i t h 0.3% Carbowax/0.1% H3PO4 on 60/80 Carbopak C ( s u p p l i e d by S u p e l c o , I n c . ) . The column was c o n d i t i o n e d i n accordance w i t h i n s t r u c t i o n s s u p p l i e d w i t h the p a c k i n g ( S u p e l c o , 1982). A few minutes p r i o r to i n j e c t i o n , samples were a c i d i f i e d t o a pH of 2 to 3 u s i n g a 1% s o l u t i o n of p h o s p h o r i c a c i d . A 1 uL sample of the a c i d i f i e d sample was withdrawn and s u b j e c t e d to gas c hromatographic a n a l y s i s . Q u a n t i f i c a t i o n was done by the e x t e r n a l s t a n d a r d method u s i n g r e a g e n t grade s t a n d a r d s d i s s o l v e d i n 0.1% aqueous p h o s p h o r i c a c i d . D i s s o l v e d oxygen c o n c e n t r a t i o n i n the b i o - r e a c t o r s was measured u s i n g Model 54A DO Meters ( Y e l l o w S p r i n g s I n s t r u m e n t Co.) . Probes were c a l i b r a t e d and membranes changed r e g u l a r l y . The pH -39-was measured u s i n g an I o n a l y z e r S p e c i f i c I o n M e t e r Model No. 401 ( O r i o n R e s e a r c h ) , and f i t t e d w i t h a c o m b i n a t i o n e l e c t r o d e . O x i d a t i o n - r e d u c t i o n p o t e n t i a l (ORP) was measured u s i n g a A g - A g C l C o m b i n a t i o n E l e c t r o d e No. 9176 m a n u f a c t u r e d by B r o a d l e y - J a m e s . Readout was m o n i t o r e d u s i n g a d i g i t a l m e t e r o r a m i c r o p r o c e s s o r u s i n g d a t a l o g g i n g s o f t w a r e . S l u d g e s e t t l i n g v e l o c i t y was me a s u r e d . u s i n g t h e s t a n d a r d S l u d g e Volume Index (SVI) o u t l i n e d i n M e t c a l f and Eddy ( 1 9 7 9 ) . A I L sample of mixed l i q u o r was drawn from t h e a e r o b i c zone and a l l o w e d t o s e t t l e i n a 1 L m e a s u r i n g c y l i n d e r f o r 30 m i n u t e s . The SVI was c a l c u l a t e d a s f o l l o w s : S V I _ Volume o c c u p i e d by t h e s l u d g e i n 30 min. (% o f 1000 mL) T o t a l M i x e d L i q u o r S u s p e n d e d S o l i d s (%) 3.2. B a t c h T e s t P r o c e d u r e F o r a l l b a t c h t e s t s , mixed l i q u o r was t a k e n from t h e a e r o b i c zone o f the p i l o t - s c a l e p r o c e s s on t h e UBC campus o r t h e f u l l s c a l e 5 - s t a g e Phoredox p r o c e s s i n Kelowna, B.C., and p l a c e d i n 1.0 o r 2.8 L E r l e n m e y e r f l a s k s and s e a l e d w i t h a r u b b e r s t o p p e r so t h a t no f r e e a i r was t r a p p e d i n the f l a s k (See F i g . 3 . 1 ) . Each s t o p p e r had a s a m p l i n g t u b e t h a t r e a c h e d t o t h e bottom of f l a s k and a r u b b e r septum t h r o u g h w h i c h a l l a d d i t i o n s were i n j e c t e d . N i t r o g e n f i l l e d r u b b e r b a l l o o n s were f i t t e d w i t h s y r i n g e n e e d l e s which were p i e r c e d t h r o u g h the septum so t h a t t h e g a s r e p l a c e d any l i q u i d w i t h d r a w n from t h e f l a s k and a n i t r o g e n a t m o sphere was m a i n t a i n e d above th e mixed l i q u o r t h r o u g h o u t t h e e x p e r i m e n t . Each f l a s k a l s o had a m a g n e t i c s t i r r e r i n i t t o p r o v i d e t h o r o u g h l y mixed c o n d i t i o n s d u r i n g t h e c o u r s e of t h e e x p e r i m e n t . I n - 4 0 -F i g . 3 . 1 . B a t c h t e s t i n g a p p a r a t u s . A f t e r C o m e a u ( 1 9 8 4 ) . -41-e x p e r i m e n t s where i t was i m p o r t a n t to c o n t r o l o r e l i m i n a t e the n i t r a t e c o n c e n t r a t i o n a t the b e g i n n i n g of the t e s t , the mixed l i q u o r was a l l o w e d to d e n i t r i f y a n a e r o b i c a l l y p r i o r to t h e experiment. T h i s u s u a l l y took a p e r i o d of about t h r e e h o u r s . Samples were withdrawn from the f l a s k a t p e r i o d i c i n t e r v a l s and c e n t r i f u g e d i m m e d i a t e l y . The c l e a r l i q u i d was then vacuum f i l t e r e d through a 0.45 mm m i l l i p o r e f i l t e r and subsampled f o r the v a r i o u s a n a l y s e s . (During the l a t e r s t a g e s of the r e s e a r c h f i l t e r i n g was done u s i n g Whatman #4 f i l t e r s i n o r d e r to save time d u r i n g the experiment. I t was found t h a t t h i s i n no way a f f e c t e d the a n a l y t i c a l r e s u l t s ) . Ortho-P a n a l y s i s was done as soon as p o s s i b l e a f t e r s a m p l i n g , u s u a l l y c o n c u r r e n t l y w i t h the e x p e r i m e n t . Samples f o r n i t r a t e / n i t r i t e a n a l y s i s were p r e s e r v e d by the a d d i t i o n of a m e r c u r i c a c e t a t e s o l u t i o n (0.1 g p h e n y l mecuric a c e t a t e d i s s o l v e d i n 20 ml a c e t o n e and 80 ml of w a t e r ) . Samples f o r VFA a n a l y s i s were e i t h e r a n a l y s e d i m m e d i a t e l y o r p r e s e r v e d by f r e e z i n g . 3.3. P i l o t P l a n t O p e r a t i o n 3.3.1. Wastewater Source The p i l o t p l a n t was s i t u a t e d on the U n i v e r s i t y of B r i t i s h Columbia campus i n Vancouver, B.C. A s c h e m a t i c diagram of the p l a n t showing the v a r i o u s components i s shown i n F i g . 3.2. The wastewater source was a main sewer l i n e t h a t s e r v i c e d the s t u d e n t r e s i d e n c e s and on-campus housing and t h e u n i v e r s i t y s p o r t s c e n t r e . Raw sewage was pumped d a i l y s t a r t i n g a t 10 a.m. w i t h a s u b m e r s i b l e macerator pump i n t o 2 m e c h a n i c a l l y mixed p l a s t i c s t o r a g e t a n k s , each w i t h a c a p a c i t y of 9000 L, u n t i l the RAW S E W A G E STORAGE TANKS SIDE 2 B I O R E A C T O R _SZ_ SECONDARY CLARIFIER E F F L U E N T R E T U R N S L U D G E SECONDARY SIDE I B I O R E A C T O R CLARIFIER E F F L U E N T 1-R E T U R N S L U D G E TWO STAGE PRIMARY SLUDGE F E R M E N T E R i ro I F i g . 3 . 2 . S c h e m a t i c l a y o u t o f t h e p i l o t p l a n t o n t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a C a m p u s -43-t a n k s were f u l l . S i n c e w a s t e w a t e r i n t h e V a n c o u v e r a r e a has low a l k a l i n i t y ( 80-120 mg/L a s CaCO^) and i s t h e r e f o r e p o o r l y b u f f e r e d , a b o u t 100 mg/L of a l k a l i n i t y ( as CaCO^) i n t h e form o f sodium b i c a r b o n a t e was added d a i l y t o t h e i n f l u e n t s t o r a g e t a n k s . T h i s k e p t the p r o c e s s pH i n t h e 6 .50-7.50 r a n g e and h e l p e d e n s u r e c o m p l e t e n i t r i f i c a t i o n a t a l l t i m e s . The i n f l u e n t COD was g e n e r a l l y i n t h e range of 200-350 mg/L and t h e TKN i n t h e range o f 25-35 mg N/L. I t was f o u n d t h a t t h e sewage was g e n e r a l l y weaker d u r i n g p e r i o d s of heavy r a i n f a l l , p r o b a b l y due t o i n f i l t r a t i o n i n t o t h e c o l l e c t i o n s y s t e m . 3.3.2. A c t i v a t e d S l u d g e P r o c e s s The p i l o t p l a n t was f i t t e d w i t h two m i l d s t e e l r e c t a n g u l a r a e r a t i o n t a n k s t h a t c o u l d e a c h be c o m p a r t m e n t a l i z e d i n t o a maximum o f s i x z o n e s u s i n g aluminum b a f f l e s . The t o t a l p r o c e s s volume c o u l d be a d j u s t e d between 2500 and 3500 l i t r e s by a d j u s t i n g t h e l e v e l o f t h e o v e r f l o w w e i r f i t t e d a t the end of e a c h b i o r e a c t o r . A e r a t i o n and m i x i n g i n t h e a e r o b i c zone o f t h e p r o c e s s was p r o v i d e d by c o a r s e b u b b l e a e r a t i o n t h r o u g h h e a d e r p i p e s a t the bottom o f t h e t a n k . The d i s s o l v e d o xygen c o n c e n t r a t i o n i n t h e a e r o b i c z o n e s was k e p t a t between 1-2 mg/L. M e c h a n i c a l m i x i n g i n t h e a n a e r o b i c and a n o x i c z o n e s was p r o v i d e d by DC motors e g u i p p e d w i t h e l e c t r o n i c s p e e d c o n t r o l l e r s and g e a r d r i v e s . M i x e d l i q u o r from t h e a e r a t i o n t a n k s f l o w e d i n t o two 5 40 l i t r e s e c o n d a r y c l a r i f i e r s e a c h e q u i p p e d w i t h two c o n c e n t r i c V - n o t c h w e i r s . Each c l a r i f i e r was a l s o e q u i p p e d w i t h a g e a r d r i v e n m e c h a n i c a l r a k e s e t to t u r n a t a b o u t 1 rpm. -4 4-The p r o c e s s sludge age was m a i n t a i n e d by w a s t i n g s l u d g e from the a e r o b i c zone of the a e r a t i o n tank once d a i l y . However, i t was found t h a t when the e f f l u e n t c o n t a i n e d a r e l a t i v e l y h i g h c o n c e n t r a t i o n of suspended s o l i d s , a s i g n i f i c a n t f r a c t i o n of the r e q u i r e d d a i l y s l u d g e wastage would o c c u r o v e r the c l a r i f i e r w e i r . As a r e s u l t , s l u d g e wastage c h a r t s , such as the one shown i n F i g . 3.3, were drawn up f o r each p r o c e s s c o n f i g u r a t i o n t e s t e d and used to c a l c u l a t e the r e q u i r e d d a i l y mixed l i q u o r wastage, t a k i n g i n t o account the s o l i d s l o s t o v e r the c l a r i f i e r w e i r . For example, i f the e f f l u e n t s o l i d s c o n c e n t r a t i o n was e q u a l to 2 5 mg/L and the p r o c e s s volume and s o l i d s c o n c e n t r a t i o n were 2750 L and 3000 mg/L, r e s p e c t i v e l y , the volume of mixed l i q u o r to be wasted was reduced from 138 to 100 l i t r e s i n o r d e r to m a i n t a i n a s l u d g e age of 20 days. 3.3.3. P i l o t P l a n t Fermenter The p i l o t p l a n t f e r m e n t e r c o n s i s t e d of a p r i m a r y c l a r i f i e r of 5 40 l i t r e s c a p a c i t y and two f i b r e g l a s s r e a c t o r s ( i n s e r i e s ) w i t h a t o t a l volume of 1000 l i t r e s . P r i m a r y s l u d g e was pumped from the c l a r i f i e r bottom i n t o the f i r s t r e a c t o r v i a a p o s i t i v e d i s p l a c e m e n t pump connected to a t i m e r . The c y c l e time was 3 0 minutes and the mean f l o w r a t e t h rough the f e r m e n t e r was s e t by a d j u s t i n g the l e n g t h of the ON t i m e . In t h i s way the d e s i r e d mean h y d r a u l i c r e t e n t i o n time and the s l u d g e age of the f e r m e n t e r were m a i n t a i n e d . M i x i n g was p r o v i d e d by a i r d r i v e n mixers equipped w i t h speed c o n t r o l l e r s . In o r d e r to m i n i m i z e a i r / l i q u i d c o n t a c t , the r e a c t o r s were f i t t e d w i t h s t y r o f o a m f l o a t i n g c o v e r s . During the l a t e r s t a g e s of t h i s r e s e a r c h , when 1 4 0 E F F L U E N T S O L I D S C O N C E N T R A T I O N ( m g / L ) Fig. 3.3. Mixed liquor wasting chart for sludge age control based on the effluent t o t a l s o l i d s concentration -46-the fermenter sludge age was i n c r e a s e d to about 10 days, a f e r m e n t e r secondary c l a r i f i e r , w i t h a volume of 130 l i t r e s , was i n s t a l l e d . Fermented s l u d g e was r e c y c l e d from the bottom of t h i s c l a r i f i e r t o the f i r s t f e r m e n t a t i o n r e a c t o r . I n t h i s c a s e , f e r m e n t e r sludge age was m a i n t a i n e d by automated wastage from the second f e r m e n t a t i o n r e a c t o r . 3.1.4. P i l o t P l a n t Sampling and A n a l y s i s D u r i n g the course of each p i l o t p l a n t e x p e r i m e n t , a r i g o r o u s weekly s c h e d u l e of 24-hour composite and grab s a m p l i n g was adhered t o . Samples of the raw i n f l u e n t , s e t t l e d sewage and e f f l u e n t from each a c t i v a t e d s l u d g e p r o c e s s were taken a u t o m a t i c a l l y e v e r y 15 m i n u t e s , pumped d i r e c t l y i n t o a r e f r i g e r a t o r , and composited o v e r 24 h o u r s . A l l o t h e r sampling was done an a grab b a s i s i n the e a r l y morning. A summary of the sampling type and frequency and the c o r r e s p o n d i n g a n a l y s i s i s shown i n Table 3.1 and the weekly d a t a l o g g i n g s c hedule i s shown i n Table 3.2. - 4 7 -Table 3.1. P i l o t P l a n t Weekly Sampling Schedule showing v a r i o u s a n a l y s e s Raw I n f l u e n t S e t t l e d Sewage B i o -Re a cto r s Fermen. R e a c t o r s E f f l u e n t E f f l u e n t ( f i l t . ) COD DC DC - - 2 WC -PO 4 - - 2WG - - 2 WC N0 3,N0 2 - - 2WG - - 2WG T o t a l P DC - - - - DC TKN DC - - - - DC VFA - - - DG - -MLSS - - 2WG - DC -SVI - - DG - - -pH 2WC - 2WG DG - -DC - D a i l y Composite DG - Da i l y Grab 2WC - Twice Weekly, D a i l y Composite 2WG - Twice Weekly Grab Table 3.2. P i l o t P l a n t Weekly Data Logging Schedule Raw P r i m a r y B i o - Fermen. R e c y c l e s E f f l u e n t I n f l u e n t Sludge R e a c t o r s R e a c t o r s  Temp. D - - D - D ORP - - C C - -Flow r a t e 3W 1W - - 3W D - D a i l y C - Continuous 1W - Once Weekly 3W - T h r i c e Weekly -48-CHAPTER FOUR BATCH TESTING RESULTS A s e r i e s of l a b o r a t o r y s c a l e b a t c h t e s t s was c a r r i e d o u t i n o r d e r t o g a i n a b e t t e r u n d e r s t a n d i n g o f t h e r o l e o f t h e a n a e r o b i c zone of the P r e m o v a l a c t i v a t e d s l u d g e p r o c e s s . In g e n e r a l , b a t c h t e s t s were d e s i g n e d t o s i m u l a t e c o n d i t i o n s i n t h e a n a e r o b i c zone and t o t e s t the e f f e c t i v e n e s s o f v a r i o u s s u b s t r a t e s a t i n d u c i n g P r e l e a s e , measure the d i s a p p e a r a n c e o f t h e s u b s t r a t e d u r i n g r e l e a s e , t h e r o l e of P r e l e a s e i n the e x c e s s r e m o v a l mechanism and t h e n e g a t i v e e f f e c t of t h e p r e s e n c e of n i t r a t e i n t h e a n a e r o b i c z one. I n t h e v a r i o u s t e s t s , t h e s l u d g e u s e d was e i t h e r drawn from the p i l o t p l a n t a t UBC o r t h e f u l l s c a l e p r o c e s s a t Kelowna, B.C. C l e a r l y t h e n , some d i f f e r e n c e s i n the e x p e r i m e n t a l r e s u l t s can be a t t r i b u t e d t o v a r i a t i o n s i n t h e b i o m a s s c h a r a c t e r i s t i c s . The most i m p o r t a n t of t h e s e d i f f e r e n c e s was t h e d e g r e e t o w h i c h e a c h f l o w - t h r o u g h p r o c e s s was b i o l o g i c a l l y a c t i v e i n r e m o v i n g e x c e s s p h o s p h o r u s a t t h e time o f t h e b a t c h t e s t . T h i s was q u a n t i f i e d by e x a m i n i n g t h e d r y w e i g h t p e r c e n t P c o n t e n t o f t h e mixed l i q u o r s l u d g e used i n t h e v a r i o u s e x p e r i m e n t s . An a d d i t i o n a l f a c t o r t h a t may e x p l a i n v a r i a n c e i n t h e r e s u l t s o f d i f f e r e n t e x p e r i m e n t s t o a l e s s e r d e g r e e i s t h e MLSS v a l u e o f t h e s l u d g e u s e d . -49-4.1. The E f f e c t i v e n e s s of V a r i o u s S u b s t r a t e s a t I n d u c i n g A n a e r o b i c P Release i n A c t i v a t e d Sludge 4.1.1. Experiment Using UBC P i l o t P l a n t Sludge The o b j e c t i v e of t h i s e x p e r i m e n t was to compare the e f f e c t of e q u i v a l e n t masses ( i n terms of COD) of v a r i o u s s u b s t r a t e s on P r e l e a s e i n a c t i v a t e d s l u d g e under a n a e r o b i c c o n d i t i o n s . The mixed l i q u o r used i n t h i s e x periment was drawn from the p i l o t p l a n t which was b e i n g o p e r a t e d i n a UCT p r o c e s s c o n f i g u r a t i o n (See F i g . 2.8). At the time of the experiment the p r o c e s s and sludge c h a r a c t e r i s t i c s were as f o l l o w s : Sludge Age = 2 0 days MLSS = 2950 mg/L P removal = 3 .50 - 1 .3 0 = 2 .20 mg P/L COD removal = 2 20 - 2 4 = 19 6 mg COD/L Sludge dry weight p e r c e n t P = 2.2% Stock s o l u t i o n s were p r e p a r e d of the v a r i o u s s u b s t r a t e s (sodium a c e t a t e , g l u c o s e , p r o p i o n i c and i s o - b u t y r i c a c i d s ) w i t h approximate COD s t r e n g t h s of 10,000 mg/L. The e x a c t COD v a l u e s were then determined a n a l y t i c a l l y . From the COD v a l u e of each s t o c k s o l u t i o n , the r e q u i r e d volume to be added to each f l a s k was c a l c u l a t e d so t h a t the COD c o n c e n t r a t i o n of the added s u b s t r a t e i n the f l a s k a t the b e g i n n i n g of the e x p e r i m e n t would be 100 mg/L. U s i n g a s y r i n g e , t h i s r e q u i r e d volume was then i n j e c t e d i n t o s e a l e d f l a s k s of mixed l i q u o r t aken from the a e r o b i c zone of the p r o c e s s and samples were drawn a t v a r i o u s time i n t e r v a l s . The samples were c e n t r i f u g e d , f i l t e r e d and the s u p e r n a t a n t a n a l y s e d f o r ortho-P c o n c e n t r a t i o n . I n t h i s experiment two -50-c o n t r o l f l a s k s were used; one which r e c e i v e d no s u b s t r a t e and a n o t h e r to which 100 mg/L (as COD) of sodium a c e t a t e was added a f t e r 2 1/2 hours. The r e s u l t s of t h i s e xperiment are p r e s e n t e d g r a p h i c a l l y i n F i g . 4.1. From the r e s u l t s p l o t t e d i n F i g . 4.1 i t can be seen t h a t more P was r e l e a s e d i n a l l f l a s k s r e c e i v i n g s u b s t r a t e than i n the c o n t r o l . Furthermore, a l t h o u g h the f l a s k s r e c e i v i n g s u b s t r a t e a l l had the same mixed l i q u o r and i n i t i a l COD c o n c e n t r a t i o n , the mass of the P r e l e a s e d i n each f l a s k d i f f e r e d s i g n i f i c a n t l y . For example, i t i s c l e a r t h a t sodium a c e t a t e i s the most e f f e c t i v e s u b s t r a t e a t i n d u c i n g P r e l e a s e , f o l l o w e d by p r o p i o n i c a c i d , g l u c o s e e t c . The e f f e c t i v e n e s s of the s u b s t r a t e appeared to v a r y as an i n v e r s e f u n c t i o n of the c a r b o n - c h a i n l e n g t h of the s u b s t r a t e . The P r e l e a s e r a t e i n the C o n t r o l I I f l a s k a f t e r the l a t e a d d i t i o n of sodium a c e t a t e appears to be comparable to the i n i t i a l r e l e a s e r a t e i n the sodium a c e t a t e e x p e r i m e n t a l f l a s k . 4.1.2. Experiment u s i n g Kelowna F u l l - S c a l e P l a n t Sludge In t h i s e x p e r i m e n t , the p r o c e d u r e of S e c t i o n 4.1.1 was r e p e a t e d on mixed l i q u o r taken from the f u l l s c a l e p l a n t a t Kelowna, B.C. At the time of the experiment the p l a n t was b e i n g o p e r a t e d i n a 5-stage M o d i f i e d Bardenpho c o n f i g u r a t i o n and was removing a s i g n i f i c a n t mass of P b i o l o g i c a l l y , as shown by the f o l l o w i n g p r o c e s s and s l u d g e c h a r a c t e r i s t i c s : -51-L E G E N O • — 9 0 a. 4 0 o E O CONTROL I • CONTROL II (Ac t lo t t addition) • SODIUM ACETATE V G L U C O S E + PROPIONIC ACID X ISO — BUTYRIC ACID m 3 0 o « ti ft 2 0 o o Acetate oddtlion to Control II I L. 3 4 T i m e ( h o u r s ) F i g . 4.1. Phosphorus r e l e a s e induced i n UBC p i l o t p l a n t sludge u s i n g v a r i o u s s u b s t r a t e s LEGEND • O CONTROL I • CONTROL II (Acetate addition) Q SODIUM ACETATE 7 G L U C O S E + PROPIONIC ACID X I S O - B U T Y R I C ACID A A C E T I C ACID A c t l a l t oddi l ion to Control II I I 3 4 T i m e ( h o u r s ) F i g . 4.2. Phosphorus r e l e a s e induced i n Kelowna p l a n t sludge u s i n g v a r i o u s s u b s t r a t e s -52-Sludge Age = 3 5 days MLSS = 3500 mg/L P removal = 5.5 - 0.2 5.8 mg P/L COD removal = 2 00 - 2 0 18 0 mg COD/L ( approx .) Sludge dry weight p e r c e n t P = 4 .5% The r e s u l t s shown i n F i g . 4.2 show a d r a m a t i c i n c r e a s e i n the c o n c e n t r a t i o n of P r e l e a s e d when compared w i t h F i g . 4.1. However, the r e s u l t s a l s o i n d i c a t e a s i m i l a r d i s t r i b u t i o n of r e l e a s e magnitudes, i . e . the degrees of r e l e a s e a r e an i n v e r s e f u n c t i o n of the carbon c h a i n l e n g t h . Sodium a c e t a t e (2-carbon c h a i n ) was the most e f f e c t i v e s u b s t r a t e a t i n d u c i n g P r e l e a s e , f o l l o w e d c l o s e l y by p r o p i o n i c a c i d (3-carbon c h a i n ) , g l u c o s e and i s o - b u t y r i c a c i d (4-carbon c h a i n ) . An i n t e r e s t i n g o b s e r v a t i o n i s t h a t a c e t i c a c i d was s i g n i f i c a n t l y l e s s e f f e c t i v e than sodium a c e t a t e a t i n d u c i n g P r e l e a s e i n t h i s e x p e r i m e n t . A p o s s i b l e e x p l a n a t i o n f o r t h i s phenomenon i s t h a t the a c i d form undergoes t r a n f o r m a t i o n to the i o n i c form (pK v a l u e = 4.80 a t 25°C) on e n t e r i n g the f l a s k which has a pH v a l u e c l o s e to n e u t r a l i t y , and t h i s t r a n s f o r m a t i o n might be a r a t e l i m i t i n g s t e p . A more l i k e l y e x p l a n a t i o n f o r t h i s phenomenon i s the form i n which the s u b s t r a t e passes through the c e l l membrane. T h i s e x p l a n a t i o n i s d e a l t w i t h i n the d i s c u s s i o n of the b i o c h e m i c a l model f o r e x c e s s b i o l o g i c a l P removal of Comeau e t a l . (1985b) i n Chapter Seven. As i n the case of the p r e v i o u s e x p e r i m e n t , the P r e l e a s e r a t e i n the c o n t r o l f l a s k t h a t r e c e i v e d a l a t e a c e t a t e a d d i t i o n was s i m i l a r to t h a t i n the e x p e r i m e n t a l a c e t a t e f l a s k . -5 3-The most s t r i k i n g d i f f e r e n c e between the two e x p e r i m e n t s , however, i s the v a s t d i f f e r e n c e i n magnitude of the P r e l e a s e d f o r each s u b s t r a t e , e.g. 72 mg/L v s . 12 mg/L of P a f t e r 3 hours f o r a s u b s t r a t e a d d i t i o n of 100 mg/L of sodium a c e t a t e (as COD). T h i s i s p r o b a b l y b e s t e x p l a i n e d by d i f f e r e n c e s i n the c h a r a c t e r i s t i c s of the two s l u d g e s used. At the time of the experiment the f u l l s c a l e p l a n t a t Kelowna was c l e a r l y e x h i b i t i n g e x c e s s b i o l o g i c a l phosphorus removal ( d r y w e i g h t % P = 4.5%) w h i l e the p i l o t p l a n t a t UBC was o n l y e x h i b i t i n g a s m a l l degree of e x c e s s b i o l o g i c a l removal (dry weight % P = 2.2%). I f one assumes t h a t most, i f not a l l , of the d i f f e r e n c e i n the P c o n t e n t of the two s l u d g e s was p r e s e n t i n the form of the s t o r e d p o l y - P , then i t i s q u i t e c l e a r t h a t the Kelowna s l u d g e had s i g n i f i c a n t l y more P a v a i l a b l e f o r r e l e a s e o r , a t l e a s t , a h i g h e r percentage of the biomass was capable of e x c e s s P s t o r a g e . The importance of dry weight % P i n the sludge and i t s r e l e v a n c e to e x c e s s b i o l o g i c a l P removal w i l l be d e a l t w i t h i n g r e a t e r d e t a i l i n C h a p t e r Seven of t h i s t h e s i s . 4.2. The E f f e c t of V a r y i n g the C o n c e n t r a t i o n of a G i v e n S u b s t r a t e on A n a e r o b i c P R e l e a s e and Subsequent A e r o b i c P Uptake i n A c t i v a t e d Sludge 4.2.1. Experiment Using UBC P i l o t P l a n t Sludge The two e x p e r i m e n t s i n the p r e v i o u s s e c t i o n c l e a r l y demonstrate t h a t sodium a c e t a t e i s an i m p o r t a n t s u b s t r a t e i n v o l v e d i n the P r e l e a s e mechanism. The o b j e c t i v e of t h i s e x periment was to model the c o n d i t i o n s p r e s e n t i n the a n a e r o b i c zone of the p r o c e s s and s u b j e c t the sludge to a range of c o n c e n t r a t i o n s of sodium a c e t a t e w i t h the view to q u a n t i f y i n g the changes i n s u p e r n a t a n t o r t h o - P -5 4-and NO3-N c o n c e n t r a t i o n w i t h t i m e . The mixed l i q u o r used i n t h i s e x periment was drawn from the a e r o b i c zone of an a n o x i c / a n a e r o b i c / a e r o b i c p i l o t s c a l e p r o c e s s a t U.B.C. The sludge was w e l l a c c l i m a t i z e d to t h e use of sodium a c e t a t e as a s u b s t r a t e s i n c e the p r o c e s s fe e d had been supplemented by the c o n t i n u o u s a d d i t i o n of 112 mg/L of sodium a c e t a t e (measured as mg COD p e r l i t r e of i n f l u e n t ) d i r e c t l y to the a n o x i c zone f o r s e v e r a l weeks p r i o r t o the expe r i m e n t . The p r o c e s s was a l s o e x h i b i t i n g a s m a l l degree of e x c e s s b i o l o g i c a l P removal ( t h i s c o n s t i t u t e d v i r t u a l l y 100% P removal, however) as can be seen i n the f o l l o w i n g p r o c e s s and s l u d ge c h a r a c t e r i s t i c s : Sludge Age = 2 0 days MLSS = 3152 mg/L P removal = 3.40 - 0.10 = 3.30 mg P/L COD removal = 198 + 112 - 26 = 284 mg COD/L Sludge d r y weight p e r c e n t P = 2.3% At the s t a r t of the e x p e r i m e n t , a range of c o n c e n t r a t i o n s of sodium a c e t a t e (20, 40, 60, 80 and 100 mg/L as COD) were i n j e c t e d i n t o the a n a e r o b i c f l a s k s . A c o n t r o l f l a s k t h a t r e c e i v e d no a c e t a t e a d d i t i o n was i n c l u d e d f o r the sake of comparison. Because of the low n i t r a t e c o n c e n t r a t i o n i n the o r i g i n a l mixed l i q u o r (2.2 mg/L NO3-N) i t was d e c i d e d t o s p i k e each r e a c t o r w i t h a sodium n i t r a t e s o l u t i o n t o b r i n g the c o n c e n t r a t i o n up by 6 mg N/L. I t was f e l t t h a t t h i s would more c l o s e l y approximate the c h a r a c t e r i s t i c s of the a n a e r o b i c zone of some of the Bardenpho t y p e - p r o c e s s and g i v e some p r e l i m i n a r y i n f o r m a t i o n r e g a r d i n g the e f f e c t of n i t r a t e e n t e r i n g the zone. -55-Th e o r t h o - P , n i t r a t e and ORP p r o f i l e s a r e p r e s e n t e d i n F i g . 4.3. E x a m i n a t i o n of the o r t h o - P p r o f i l e s shows t h a t each p r o f i l e appears to have two d i s t i n c t r e l e a s e phases; a v e r y r a p i d i n i t i a l r e l e a s e r a t e which appears to be s i m i l a r f o r a l l the e x p e r i m e n t a l f l a s k s and i n which the degree of P r e l e a s e appears to be a f u n c t i o n of the i n i t i a l s u b s t r a t e c o n c e n t r a t i o n , f o l l o w e d by a s i g n i f i c a n t l y s l o w e r r a t e a t which r e l e a s e c o n t i n u e s f o r the d u r a t i o n of the a n a e r o b i c p e r i o d . Furthermore, i n the f l a s k s t h a t r e c e i v e d l o w e r a c e t a t e dosages and e x h i b i t e d t h i s i n i t i a l r a p i d r e l e a s e (40 and 60 mg COD/L e x p e r i m e n t a l f l a s k s ) , a c e r t a i n degree of P uptake o c c u r r e d i n the time p e r i o d a f t e r the i n i t i a l r e l e a s e . E x a m i n a t i o n of the n i t r a t e p r o f i l e s ( F i g . 4.3b) shows t h a t o ver t h i s p e r i o d of P u p t a k e , n i t r a t e was s t i l l p r e s e n t i n the r e a c t o r s , i . e . complete d e n i t r i f i c a t i o n had not y e t o c c u r r e d . I t i s assumed t h a t i n the f l a s k s t h a t r e c e i v e d the lower i n i t i a l s u b s t r a t e c o n c e n t r a t i o n , s u b s t r a t e l i m i t i n g c o n d i t i o n s were p r e s e n t i n the f l a s k s a t t h i s p o i n t . T h i s s i t u a t i o n i s analogous to the a n o x i c zone of the Bardenpho-type p r o c e s s e s where P uptake i s known to o c c u r i n c a s e s where s u b s t r a t e i s l i m i t i n g and n i t r a t e i s e n t e r i n g the zone v i a the i n t e r n a l r e c y c l e from the a e r o b i c zone of the p r o c e s s . Many a c t i v a t e d sludge organisms a r e known to f o l l o w a l m o s t s i m i l a r m e t a b o l i c pathways when u s i n g e i t h e r oxygen o r n i t r a t e as the f i n a l e l e c t r o n a c c e p t o r . The ORP p r o f i l e s p r e s e n t e d i n F i g . 4.3c ( o n l y 4 f l a s k s were monitored) do not demonstrate t h a t a minimum a b s o l u t e l e v e l of redox p o t e n t i a l d e f i n e s the n e c e s s a r y p r e r e q u i s i t e f o r P - 5 6 -CD J , Cu I O o F i g Legend CONTROL 20 m g COD/L  40 m g COD/L  60 m g COD/L  8 0 mg COD/L  100 m g COD/L 3 4 5 TIME (hours) 4.3a. O r t h o - P c o n c e n t r a t i o n p r o f i l e s : The e f f e c t o f s u b s t r a t e c o n c e n t r a t i o n on a n a e r o b i c P r e l e a s e - n i t r i f i e d s l u d g e ( S e c t i o n 4.2.1) 10 r Legend • CONTROL A • V o o 20 m g COD/L  40 m g COD/L  60 m g COD/L  8 0 m g COD/L  100 m g COD/L 3 4 5 TIME (hours) 8 F i g . 4.3b, N i t r a t e c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of s u b s t r a t e c o n c e n t r a t i o n on a n a e r o b i c P r e l e a s e - n i t r i f i e d s l u d g e ( S e c t i o n 4.2.1) - 5 7 -200 r Legend CONTROL 20 mg COD/L 40 mg COD/L 80 mgCOp/L -400 0 1 2 3 4 5 6 7 TIME (hours) F i g . 4.3c. ORP p r o f i l e s : The e f f e c t of substrate concentration on anaerobic P release • n i t r i f i e d sludge (Section 4.2.1) 8 -58-r e l e a s e . Q u i t e c l e a r l y , h i g h e r l e v e l s of s u b s t r a t e caused the ORP l e v e l of the f l a s k t o drop a t a h i g h e r r a t e and to g r e a t e r n e g a t i v e v a l u e s than i n the c o n t r o l f l a s k , b ut P r e l e a s e commenced v i r t u a l l y i m m e d i a t e l y upon s u b s t r a t e a d d i t i o n and p r i o r t o the h i g h n e g a t i v e v a l u e s b e i n g a t t a i n e d . T h i s may be a t t r i b u t a b l e to the e x p e r i m e n t a l p r o c e d u r e used. I t i s known, f o r example, t h a t ORP e l e c t r o d e s may r e q u i r e s e v e r a l hours o r even days of c o n d i t i o n i n g time i n a g i v e n s o l u t i o n b e f o r e g i v i n g a c c u r a t e a b s o l u t e measurement. I t i s , t h e r e f o r e , p o s s i b l e t h a t t h i s time lag-between h i g h l y n e g a t i v e ORP v a l u e s b e i n g a t t a i n e d i n the f l a s k s and the onset of P r e l e a s e i s p r i m a r i l y due to the lo n g e l e c t r o d e response t i m e . The ORP p r o f i l e s do, however, show an i n t e r e s t i n g phenomenon w i t h r e g a r d t o the d e n i t r i f i c a t i o n k i n e t i c s . For the t h r e e p r o f i l e s measured, t h e r e e x i s t s a d e f i n i t e i n c r e a s e i n the r a t e of the drop i n ORP as marked by an a s t e r i s k * i n F i g . 4.3c ( t h i s i s c l e a r l y a p p a r e n t i n the 20 and 40 mg COD/L f l a s k s , but not e a s i l y v i s i b l e i n the 80 mg COD/L f l a s k , where the i n i t i a l r a t e of change i n ORP was the g r e a t e s t . The n i t r a t e p r o f i l e s i n F i g . 4.3c c l e a r l y show t h a t these "bends" i n the ORP p r o f i l e s are c o i n c i d e n t w i t h the t o t a l d i s a p p e a r a n c e of n i t r a t e from s o l u t i o n . T h i s can be e x p l a i n e d by the f a c t t h a t n i t r a t e i s a s t r o n g o x i d i z i n g agent as demonstrated by i t s h i g h s t a n d a r d e l e c t r o d e p o t e n t i a l (E° = +0.42v § 25°C). T h i s experiment c l e a r l y demonstrates t h a t the. mass of P r e l e a s e d i s a f u n c t i o n of the mass of s u b s t r a t e a v a i l a b l e t o t h e organisms under a n a e r o b i c c o n d i t i o n s . However, i n o r d e r t o o b t a i n i n f o r m a t i o n r e g a r d i n g the f a t e of the s u b s t r a t e and i t s -59-possible connection to P release, substrate p r o f i l e s are also required. In addition, because some of the substrate i s also u t i l i z e d in the d e n i t r i f i c a t i o n reaction (8.6 mg COD per mg N by stoichiometry), i t i s clear that the presence of n i t r a t e i n the flask at the st a r t of the experiment introduced a confounding variable, primarily due to the substrate requirement for denitr i f i c a t i o n . These two factors were considered i n the design of the experiment reported in Section 4.2.2. 4.2.2. Experiment Using D e n i t r i f i e d UBC P i l o t Plant Sludge This experiment had a s i m i l a r procedure to that discussed i n Section 4.2.1 except that the mixed liq u o r was stored anaerobically for about three hours p r i o r to the s t a r t of the experiment in order to allow complete d e n i t r i f i c a t i o n to take place. A l l samples drawn were a c i d i f i e d and analysed f o r VFA concentration so that the fate of the substrate during anaerobic P release could be determined. A t h i r d modification to this experiment was that an additional 4-hour aerobic phase was included immediately a f t e r the 3-hour anaerobic phase, i n order to measure the P uptake and to determine whether i t was in any way related to the degree of anaerobic release. The mixed l i q u o r used was drawn from a 3-phase anoxic/anaerobic/aerobic process that was receiving a continuous acetate addition of 24 mg/L (measured as mg COD per l i t r e of influent) at the time of the experiment. The process and sludge c h a r a c t e r i s t i c s were as follows: -6 0-Sludge Age = 20 days MLSS = 3550 mg/L P Removal = 3.80 - 0.10 = 3.70 mg P/L COD removal = 249 + 2 4 - 25 = 2 48 mg COD/L Sludge dry weight p e r c e n t P = 3.2% In o r d e r to s i m p l i f y the e x p e r i m e n t , the number of e x p e r i m e n t a l f l a s k s was reduced t o f o u r . At the s t a r t of the e x p e r i m e n t , the f o u r e x p e r i m e n t a l f l a s k s r e c e i v e d a c e t a t e dosages of 25, 5 0, 75, and 100 mg/L as COD, r e s p e c t i v e l y . The c o n t r o l f l a s k r e c e i v e d no s u b s t r a t e a d d i t i o n . J u s t p r i o r t o t u r n i n g on the a i r s u p p l y ( i . e . 15 minutes b e f o r e the end of the a n a e r o b i c phase) the f l a s k s were each s p i k e d w i t h a sodium phosphate s o l u t i o n ( a p p r o x i m a t e l y 45 mg P/L) i n o r d e r t o ensure t h a t P l i m i t i n g c o n d i t i o n s d i d not o c c u r d u r i n g the a e r o b i c phase. The o r t h o - P , a c e t a t e and ORP p r o f i l e s are p r e s e n t e d i n F i g . 4.4. The most apparent d i f f e r e n c e between the r e s u l t s of t h i s experiment and those of S e c t i o n 4.2.1 i s the s i g n i f i c a n t i n c r e a s e i n the mass of P r e l e a s e d under a n a e r o b i c c o n d i t i o n s f o r the same s u b s t r a t e a d d i t i o n , i . e . 60 mg P/L vs 12 mg P/L a f t e r t h r e e hours i n the f l a s k t h a t r e c e i v e d an i n i t i a l s u b s t r a t e c o n c e n t r a t i o n of 100 mg COD/L. T h i s can p r o b a b l y be a t t r i b u t e d t o two f a c t o r s : f i r s t l y , by c o m p l e t e l y d e n i t r i f y i n g the s l u d g e p r i o r to the s t a r t of the experiment the s u b s t r a t e r e q u i r e m e n t f o r d e n i t r i f i c a t i o n was removed; and s e c o n d l y , the dry w e i g h t % P c o n t e n t of the sludge used i n t h i s experiment was s i g n i f i c a n t l y h i g h e r than i n the p r e v i o u s experiment (3.2% v s . 2.2%) and, t h e r e f o r e , more -61-Legend 0 1 2 3 4 5 6 7 8 TIME (hours) F i g . 4.4a. Ortho-P c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of sub s t r a t e c o n c e n t r a t i o n on P r e l e a s e and uptake - d e n i t r i f i e d sludge ( S e c t i o n 4.2.2) F i g . 4.4b. Acetate c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of sub s t r a t e c o n c e n t r a t i o n on P r e l e a s e and uptake - d e n i t r i f i e d sludge ( S e c t i o n 4.2.2) - 6 2 -O < I < I Q _ o 200 r 100 ANAEROBIC > AEROBIC -100 --200 --300 Legend CONTROL 25 mg COD/L 50 mg COD/L 75 mg .COD/L 100 mg COD/L _i I - 3 - 2 -1 0 1 2 3 4 5 6 TIME (hours) F i g 4.4c. ORP p r o f i l e s : The e f f e c t of s u b s t r a t e c o n c e n t r a t i o n on P r e l e a s e and uptake - d e n i t r i f i e d s l u d g e ( S e c t i o n 4.2.2) 8 0 25 50 75 100 AVAILABLE COD (mg/L) F i g . 4.5. The e f f e c t of i n c r e a s i n g the i n i t i a l s u b s t r a t e c o n c e n t r a t i o n on the n e t P r e l e a s e a f t e r 2 hours i n S e c t i o n 4.2.2 - 6 3 -s t o r e d P was a v a i l a b l e f o r r e l e a s e . From F i g . 4 . 4 i t can be seen t h a t once a g a i n the same 2 - s t a g e phosphorus r e l e a s e p r o f i l e s were observed w i t h the e x t e n t o f t he i n i t i a l r a p i d r e l e a s e b e i n g a f u n c t i o n o f the i n i t i a l s u b s t r a t e c o n c e n t r a t i o n . F u r t h e r m o r e , i t can be seen t h a t the o r t h o - P p r o f i l e s f o r t he 75 and 100 mg COD/L e x p e r i m e n t a l f l a s k s a re a l m o s t i d e n t i c a l , i n d i c a t i n g t h a t t h e r e e x i s t s a d e f i n i t e upper l i m i t t o the mass o f P t h a t can be r e l e a s e d by a g i v e n s l u d g e . I n c r e a s i n g t h e c o n c e n t r a t i o n o f s u b s t r a t e a v a i l a b l e t o the o rgan isms beyond t h i s l i m i t does n o t r e s u l t i n a d d i t i o n a l P r e l e a s e . T h i s upper l i m i t i s , i n a l l l i k e l i h o o d , a f u n c t i o n o f t he c h a r a c t e r i s t i c s o f t he s ludge used i n the e x p e r i m e n t . A t o t a l P r e l e a s e o f 6 0 mg/L f rom a s ludge w i t h a MLSS c o n c e n t r a t i o n o f 3550 mg/L r e p r e s e n t s a p e r c e n t d r y w e i g h t l o s s o f 1.7%. T h e r e f o r e , t he c e l l s r e t u r n e d t o a d r y w e i g h t % P c o n t e n t o f 3 .2 - 1.7 = 1.5%, i . e . t he a c c e p t e d P c o n t e n t o f c e l l s i n wh ich t h e r e i s no excess b i o l o g i c a l P a c c u m u l a t i o n (Hoffmann and M a r a i s , 1 9 7 7 ) . Thus, g i v e n s u f f i c i e n t s u b s t r a t e and a long enough p e r i o d o f a n a e r o b i o s i s , c e l l s t h a t have accumu la ted excess P w i l l r e l e a s e a l l o f t h i s s t o r e d P t o t he s u p e r n a t a n t . A g r a p h o f n e t P r e l e a s e ( i . e . e x p e r i m e n t a l f l a s k P r e l e a s e minus c o n t r o l f l a s k P r e l e a s e ) a f t e r two hours f o r each o f the e x p e r i m e n t a l f l a s k s p l o t t e d a g a i n s t the a v a i l a b l e COD c o n c e n t r a t i o n a t the s t a r t o f t h e e x p e r i m e n t i s shown i n F i g . 4 . 5 . The g r a p h shows a l i n e a r r e l a t i o n s h i p between P r e l e a s e and a v a i l a b l e s u b s t r a t e c o n c e n t r a t i o n w i t h a s l o p e o f about 0 .75 mg P/mg COD f o r l o w e r s u b s t r a t e c o n c e n t r a t i o n s . At h i g h e r a v a i l a b l e s u b s t r a t e c o n c e n t r a t i o n s t he p l o t becomes h o r i z o n t a l a t -64-a higher net release of 50 mg P/L. The acetate concentration p r o f i l e s in Fig. 4.4 present some important clues regarding the i n t e r r e l a t i o n s h i p between substrate u t i l i z a t i o n and P release. The HAc p r o f i l e s for a l l the experimental flasks show that substrate u t i l i z a t i o n by the c e l l s (as represented by the disappearance of sodium acetate from the supernatant)" occurs during the rapid P release phase at a rate that i s independent of the i n i t i a l substrate concentration. Furthermore, the cessation of substrate u t i l i z a t i o n i s coincident with the end of the rapid release phase. In the case of the 25 and 5 0 mg COD/L experimental flasks this occurs due to the onset of substrate l i m i t i n g conditions i n the flasks, but in the case of the 75 and 100 mg COD/L flasks the c e l l s appear to have l o s t the a b i l i t y to take up the remaining substrate. It seems l i k e l y , therefore, that P release plays an integral role i n the transport of the substrate from the supernatant into the c e l l and that the i n t e r r e l a t i o n s h i p of these two phenomena warrants closer examination. A plot of the P release vs. the corresponding substrate u t i l i z a t i o n during the rapid release phase for time intervals of 10, 20, 30, 40, 60, 90 and 120 minutes i s shown i n Fig. 4.6. There is an excellent c o r r e l a t i o n (r = 0.989) between the two phenomena indicating that there e x i s t s some direc t or indir e c t exchange of the two molecules across the c e l l wall under anaerobic conditions. The least sguares l i n e drawn through the points has a slope of 0.91 indicating that 0.91 mg of P are released for every mg of HAc taken up by the c e l l s . Converting this r a t i o to the molar form: -65-= 0.91 (60/30.94) = 1.7 6 moles P/mole HAc i.e. 1.76 moles of P are released for every mole of HAc taken up by the c e l l s . This observation, together with i t s relevance to the concept of s p e c i f i c substrate induced excess b i o l o g i c a l P removal in the activated sludge process, i s dealt with in greater d e t a i l in Chapter Seven. From Fi g . 4.6 i t can be seen that the line drawn through the points does not pass through the o r i g i n but intersects the HAc axis at about 4 mg/L. Two possible explanations for this phenomenon are that a small mass of substrate is adsorbed onto the sludge or experimental apparatus, or that there exists some small metabolic requirement that i s independent of the P release mechanism. From the ORP p r o f i l e s presented in Fig. 4.4, i t can be seen that ORP measurement was used during the pre-experimental sludge denitr i f ication phase in order to determine when the zero n i t r a t e condition had been reached. Slope changes i n the p r o f i l e s , s i m i l a r to those observed in the previous experiment, occurred during a period of approximately 10 minutes p r i o r to the sta r t of the experiment, probably indicating that a zero n i t r a t e condition had been reached. During the course of the experiment, however, there appears to be no s p e c i f i c trend i n the ORP measurements. Although the experimental flasks had consistently more negative ORP readings than the control flask during the anaerobic phase, this may have been a function of the electrode used i n the control flask as the control readings were also less negative during the pre-experiment d e n i t r i f i c a t i o n phase. -66-SUBSTRATE UTILIZATION (mg HAc/L) F i g . 4.6. P h o s p h o r u s r e l e a s e v e r s u s s u b s t r a t e u t i l i z a t i o n i n S e c t i o n 4.2.2 LU < I-Q_ ZD O CO o t r LJ < 3 6 0 i -5 0 -x < 5 0 m g C O D / L ° ' o 7 5 m g C O D / L o lOOmg C O D / L F i g . 0 10 2 0 30 4 0 50 60 ANAEROBIC P R E L E A S E ( m g P / L ) 4.7. A e r o b i c P u p t a k e v e r s u s a n a e r o b i c P r e l e a s e i n S e c t i o n 4.2.2 -67-Results for the aerobic phase were, in general, less conclusive than those of the anaerobic phase. The ortho-P p r o f i l e s i n F i g . 4.4 show that although the flasks exhibited a s i g n i f i c a n t degree of P uptake under aerobic conditions, the control and the 25 and 50 mg COD/L experimental flasks ( i n that order) began to release P back into the supernatant during the course of the aerobic phase. A possible explanation may l i e in the experimental procedure i t s e l f - the long anaerobic time period between the drawing of the mixed liquor from the p i l o t plant and the onset of aerobic conditions, 6 hours, may have caused a s i g n i f i c a n t degree of c e l l l y s i s under the aerobic conditions (where substrate l i m i t i n g conditions prevailed), which would resu l t i n the re-release of the stored P back into the supernatant. In spite of this observation, there does appear to be a loose c o r r e l a t i o n between the mass of P released under anaerobic conditions and the mass of P taken up under subsequent aerobic conditions (See Fig. 4.7). However, the aerobic phase of the ortho-P p r o f i l e s shown i n Fig. 4.4 show that there appears to be an upper l i m i t to the P uptake capacity of the c e l l s of a given biomass under batch testing conditions. 4.3. The Effect of Varying the Level of Nitrate for a Given I n i t i a l Substrate Concentration on Anaerobic P Release and Subsequent P Uptake i n Activated Sludge. . 4.3.1. Experiment Using UBC P i l o t Plant Sludge and Excess Substrate. In Section 4.2 i t was shown that the presence of n i t r a t e at the s t a r t of an anaerobic batch test appears to have a negative e f f e c t on the P release mechanism due to the substrate -68-requirement for d e n i t r i f i c a t i o n . In addition, the nitrat e entering the anaerobic zone of f u l l - s c a l e activated sludge processes is known to have a confounding e f f e c t on the P release mechanism and on the P removal c h a r a c t e r i s t i c s of the processes. The objective of this experiment was to quantify the eff e c t of the presence of nitra t e in the flasks at the st a r t of a batch test on the anaerobic P release and aerobic P uptake mechanisms. Sludge used in this experiment was drawn from a 3-stage anoxic/ anaerobic/aerobic process that was receiving a continuous sodium acetate addition of 37 mg COD/L and exhibiting excess b i o l o g i c a l P removal. The process and sludge c h a r a c t e r i s t i c s were as f o Hows: Sludge age = 20 days MLSS = 3900 mg/L P removal = 3.84 - 0.57 = 3.27 mg P/L COD removal = 266 + 37 - 30 = 273 mg COD/L Sludge dry weight percent P = 3.4% Pri o r to the start of the batch experiment, the sludge was allowed to d e n i t r i f y completely so that the i n i t i a l n i t r a t e concentration could be controlled. In order that P l i m i t i n g conditions did not occur during the aerobic phase, the flasks were each spiked with 24 mg/L of P. At the s t a r t of the experiment, the control flask and each of the experimental flasks received an i n i t i a l sodium acetate substrate concentration of 100 mg/L (as COD). In addition, the four experimental flasks received 3, 6, 9 and 12 mg/L of n i t r a t e (as N) , respectively, by injecting the appropriate volumes of a stock sodium nitra t e -69-solution. The ortho-P, acetate and ni t r a t e concentration p r o f i l e s for the five flasks are presented i n F i g . 4.8. From the ortho-P concentration p r o f i l e i t can be seen that the P release mechanism was v i r t u a l l y unaffected by the i n i t i a l n i t r a t e concentrations of 3, 6 and 9 mg N/L. In the flask with the i n i t i a l n i t r a t e concentration of 12 mg N/L, P release was s l i g h t l y inhibited with the f i n a l concentration of P released being approximately 20% lower than in the other f l a s k s . The ni t r a t e concencentration p r o f i l e s show that d e n i t r i f i c a t i o n occurred at a steady rate that was v i r t u a l l y i d e n t i c a l for a l l the flasks. The VFA p r o f i l e s i n Fig. 4.8 for the control flask and the 3 mg N/L experimental flask show that the substrate was not li m i t i n g in these flasks for the duration of the anaerobic phase. In the case of the 6 and 9 mg N/L experimental fl a s k s , substrate became li m i t i n g a f t e r complete d e n i t r i f i c a t i o n had taken place. Only in the case of the 12 mg N/L flask did the substrate concentration reach zero p r i o r to the completion of d e n i t r i f i c a t i o n . Furthermore, there appears to be a s i g n i f i c a n t decrease in the substrate u t i l i z a t i o n rate that i s coincidental with the ni t r a t e concentration reaching zero. It appears, therefore, that the presence of up to 9 mg/L of ni t r a t e had v i r t u a l l y no effect on the P release mechanism and that i t may be possible to explain this phenomenon by the fact that an excess concentration of substrate was present in the flasks at the s t a r t of the expe riment. - 7 0 -0 > CD Q _ I o X r— cr O 8 0 6 0 -4 0 -2 0 -ANAEROBIC < - * — o AEROBIC 3 4 5 TIME (hours) Legend CONTROL 3 mg N03-N/L  6 mg N03-N/L  9 mg N03-N/L  12 mg N03-N/L 8 F i g . 4.8a. Ortho-P c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of n i t r a t e on P r e l e a s e and uptake - excess s u b s t r a t e c o n d i t i o n s ( S e c t i o n 4.3.1) ANAEROBIC < - • - > AEROBIC Fig, • * 3 4 5 TIME (hours) Legend • CONTROL A 3 m g N 0 3 - N / L • 6 mg N 0 3 - N / L V 9 mg N 0 3 - N / L O 12 mg N 0 3 - N / L 8 4.8b. N i t r a t e c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of n i t r a t e on P r e l e a s e and uptake - excess s u b s t r a t e c o n d i t i o n s ( S e c t i o n 4.3.1) -71-TIME (hours) Fig. 4.8c. Acetate concentration p r o f i l e s : The ef f e c t of nitrate on P release and uptake - excess substrate conditions (Section 4.3.1) -72-The r e s u l t s of t h i s experiment suggest t h a t de n i t r i f i c a t i o n and the P r e l e a s e mechanism a r e s u b s t r a t e u t i l i z a t i o n mechanisms t h a t a r e not m u t u a l l y e x c l u s i v e . For example, the de n i t r i f i c a t i o n k i n e t i c t h e o r y of van Haandel e t a l . (1981) i s based on a s t o i c h i o m e t r i c r e l a t i o n s h i p i n the o x i d a t i o n of s u b s t r a t e u s i n g n i t r a t e as the f i n a l e l e c t r o n a c c e p t o r . The model assumes t h a t 8.6 mg of s u b s t r a t e (as COD) a r e r e q u i r e d i n the r e d u c t i o n of 1 mg of n i t r a t e (as N) . A c c o r d i n g to t h e t h e o r y of S i e b r i t z e t a l . ( 1983), s u b s t r a t e t h a t i s u t i l i z e d f o r d e n i t r i f i c a t i o n i n the a n a e r o b i c r e a c t o r i s rendered u n a v a i l a b l e f o r the e x c e s s b i o l o g i c a l P removal mechanism i n p r o c e s s e s d e s i g n e d f o r enhanced b i o l o g i c a l P r e m o v a l . However, i n t h i s e x p e r i m e n t i t seems u n l i k e l y t h a t t h e r e was p r e f e r e n t i a l usage of the a v a i l a b l e a c e t a t e i n the d e n i t r i f i c a t i o n r e a c t i o n , i . e . t h a t s u b s t r a t e u t i l i z e d f o r d e n i t r i f i c a t i o n was r endered u n a v a i l a b l e f o r the P r e l e a s e mechanism. For example, i n the case of the 9 mg N/L e x p e r i m e n t a l f l a s k , the h y p o t h e t i c a l s u b s t r a t e r e q u i r e m e n t f o r d e n i t r i f i c a t i o n was 9.0 X 8.6 = 77 mg COD/L, a c c o r d i n g to t h e t h e o r y of van Haandel e t a l . T h i s i m p l i e s t h a t o n l y 23 mg COD/L was a v a i l a b l e f o r the P r e l e a s e mechanism. T h i s seems u n l i k e l y when one c o n s i d e r s t h a t P r e l e a s e was v i r t u a l l y u n a f f e c t e d by the i n i t i a l p resence of up to 9 mg/L of n i t r a t e i n the e x p e r i m e n t a l f l a s k s . However, i t i s p o s s i b l e t h a t the s u b s t r a t e t h a t i s f i r s t t aken up by the c e l l s i n the P r e l e a s e mechanism, i s s t o r e d i n t r a c e l l u l a r l y and l a t e r u t i l i z e d i n the de n i t r i f i c a t i o n r e a c t i o n ; t h i s would a l l o w the same s u b s t r a t e to p e r f o r m two f u n c t i o n s i n a g i v e n e x p e r i m e n t a l f l a s k . T h i s s i t u a t i o n i s - 7 3 -u n l i k e l y t o o c c u r i n a s i n g l e zone o f a c o n t i n u o u s f l o w - t h r o u g h p r o c e s s . T h i s a s p e c t w i l l be d e a l t w i t h i n g r e a t e r d e t a i l i n the p r e s e n t a t i o n o f an i n t e g r a t e d model f o r a n a e r o b i c P r e l e a s e i n Chap te r Seven o f t h i s t h e s i s . An a d d i t i o n a l q u e s t i o n t h a t i s r a i s e d by the r e s u l t s o f t h i s e x p e r i m e n t i s w h e t h e r o r n o t the p resence o f the same i n i t i a l c o n c e n t r a t i o n s o f n i t r a t e a t the s t a r t o f the e x p e r i m e n t wou ld have had a more d e t r i m e n t a l e f f e c t on the a n a e r o b i c P r e l e a s e mechanism i n a case where the i n i t i a l s u b s t r a t e c o n c e n t r a t i o n i n t he f l a s k s had been s i g n i f i c a n t l y l o w e r , i . e . had s u b s t r a t e l i m i t i n g c o n d i t i o n s p r e v a i l e d i n t h e f l a s k s f o r a g r e a t e r p e r i o d o f t i m e . The q u e s t i o n of t he e f f e c t o f n i t r a t e on t h e P r e l e a s e mechanism u n d e r l i m i t e d s u b s t r a t e a v a i l a b i l i t y i s addressed i n the f o l l o w i n g e x p e r i m e n t . 4 . 3 . 2 . Expe r imen t Us ing UBC P i l o t P l a n t S ludge and L i m i t e d S u b s t r a t e The r e s u l t s o f t he p r e v i o u s e x p e r i m e n t show t h a t when excess s i m p l e s u b s t r a t e i s a v a i l a b l e , a n a e r o b i c P r e l e a s e i s n o t s e v e r e l y i n h i b i t e d by the p resence o f n i t r a t e i n c o n c e n t r a t i o n s l i k e l y t o be found i n a n i t r i f y i n g n u t r i e n t remova l p r o c e s s . The o b j e c t i v e o f t h i s e x p e r i m e n t was t o q u a n t i f y the e f f e c t o f t h e same range of i n i t i a l n i t r a t e c o n c e n t r a t i o n s on the P r e l e a s e mechanism under s u b s t r a t e l i m i t i n g c o n d i t i o n s . At the t ime o f the e x p e r i m e n t , the p i l o t p l a n t was o p e r a t i n g under c o n d i t i o n s s i m i l a r t o those o f the p r e v i o u s e x p e r i m e n t , e x c e p t t h a t the c o n t i n u o u s sodium a c e t a t e a d d i t i o n was reduced t o 28 mg/L (as COD). The p r o c e s s and s ludge c h a r a c t e r i s t i c s were as f o l l o w s : -74-Sludge Age =20 days MLSS = 4365 mg/L P Removal = 5.3 - 0.8 = 4.5 mg P/L COD Removal= 309 + 28 - 24 = 3 13 mg COD/L Sludge dry weight percent P = 3.0% The i n i t i a l n itrate concentrations in the experimental flasks were kept at 3, 6, 9 and 12 mg N/L, respectively, and the i n i t i a l sodium acetate dosage was reduced from 100 to 50 mg/L (as COD). The ortho-P, n i t r a t e and acetate p r o f i l e s are presented i n F i g . 4.9. From the ortho-P p r o f i l e s in Fig. 4.9, i t can c l e a r l y be seen that the presence of n i t r a t e in the flasks at the beginning of the experiment had a s i g n i f i c a n t l y greater negative ef f e c t on the P release mechanism than in the previous experiment. The ortho-P p r o f i l e s for the control and the 3 and 6 mg N/L experimental flasks show si m i l a r release trends to those observed in Section 4.2.2, where no n i t r a t e was present at the s t a r t of the experiment, i . e . a rapid i n i t i a l release rate followed by a slower release rate which continued for the remainder of the anaerobic time period. The magnitude of the i n i t i a l P release was adversely affected by the i n i t i a l presence of 3 mg/L of NO3-N and, to a greater extent, by the presence of 6 mg/L of NO3-N. This e f f e c t was similar in fashion to the way in which the magnitude of the i n i t i a l release phase was determined by the i n i t i a l substrate concentration in Section 4.2.2. The ortho-P p r o f i l e s for the 6 and 9 mg/L of n i t r a t e experimental flasks demonstrate an interesting phenomenon previously observed in Section 4.2.1 - aft e r the rapid i n i t i a l P release, P uptake -75-80 r ANAEROBIC o o AEROBIC co-co I o o 3 4 5 TIME (hours) CONTROL 3 mg N 0 3 - N / L  6 mg N 0 3 - N / L  9 mg N 0 3 - N / L  12 mg N 0 3 - N / L 8 F i g . 4.9a. O r t h o - P c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of n i t r a t e o n P r e l e a s e a n d u p t a k e - s u b s t r a t e l i m i t i n g c o n d i t i o n s ( S e c t i o n 4.3.2) ANAEROBIC <J—•—o AEROBIC 3 4 5 TIME (hours) Legend • CONTROL A 3 mg N 0 3 - N / L • 6 mg N 0 3 - N / L V 9 mg N 0 3 - N / L O 12 mg N 0 3 - N / L 8 F i g . 4.9b. N i t r a t e c o n c e n t r a t i o n p r o f i l e s : The e f f e c t of n i t r a t e o n P r e l e a s e a n d u p t a k e - s u b s t r a t e l i m i t i n g c o n d i t i o n s ( S e c t i o n 4.3.2) - 7 6 -Legend • CONTROL A 3 mg N 0 3 - N / L • 6 mg N 0 3 - N / L V 9 m g N 0 3 - N / L O 12 m g N 0 3 - N / L 0 1 2 3 4 5 6 7 8 TIME (hours) Fig. 4.9c. Acetate concentration p r o f i l e s : The ef f e c t of ni t r a t e on P release and uptake - substrate l i m i t i n g conditions (Section 4.3.2) - 7 7 -occurs before the slower release rate commences. Examination of nit r a t e and acetate p r o f i l e s in Fig 4.9 indicate that for these two reactors, the end of the rapid P release phase i s coincident with the substrate concentration reaching zero but that n i t r a t e is s t i l l present in solution, i . e . complete denitr i f i c ation has not yet occurred. P release only resumes at the slower rate once a l l the ni t r a t e has disappeared from solution. This seems to suggest that some of the substrate stored by the organisms during the rapid P release phase i s u t i l i z e d by the organisms for d e n i t r i f i c a t i o n . Such d e n i t r i f i c a t i o n in the absence of substrate being available from the solution i s characterized by a net uptake of P. In order to quantify the negative e f f e c t of n i t r a t e on P release, P release a f t e r three hours i s plotted against the i n i t i a l n i t r a t e concentration in Fig. 4.10. It can be seen from the graph that the relationship appears to be l i n e a r for ni t r a t e concentrations up to about 6 mg N/L with a loss of 3.0 mg/L of P release for every mg N/L of n i t r a t e i n i t i a l l y present at the start of the experiment. For i n i t i a l concentrations of n i t r a t e greater than about 6 mg N/L, the negative e f f e c t of the presence of n i t r a t e tends to decrease s l i g h t l y . The relationship between the substrate u t i l i z e d and the corresponding P release in the control reactor (no n i t r a t e addition) i s shown in Fig. 4.11. The graph shows a l i n e a r relationship with a slope of 0.89 which i s within 2% of the slope obtained for the same two variables i n Section 4.2.2 (See Fig. - 7 8 -0 3 6 9 12 INITIAL N I T R A T E CONCENTRATION ( m g N / L ) Fig. 4.10. Effect of increasing the i n i t i a l n i t r a t e concentration on P release i n Section 4.3.2 S U B S T R A T E UTILIZATION (mg HAc/L) Fig. 4.11. Substrate u t i l i z a t i o n versus P release for the control reactor i n Section 4.3.2 -79-4.6). T h i s c o n f i r m s t h a t f o r e v e r y mg a c e t a t e (as HAc) l o s t from s o l u t i o n i n the absence of n i t r a t e , 0.89 mg of P a r e r e l e a s e d . T h i s r e p r e s e n t s a molar r a t i o o f : 0.89 (60/30.94) = 1.75 moles P/mole HAc On the o t h e r hand, d e n i t r i f i c a t i o n t h e o r y of van Haandel e t a l . (1981) s t a t e s t h a t 8.08 mg of HAc (1 mg COD = 0.94 mg HAc) are r e q u i r e d t o d e n i t r i f y 1 mg of NO3-N. T h i s , i n t u r n , r e p r e s e n t s a molar r a t i o o f : 8.08 ( 14/60) = 1 .89 moles HAc/mole N By combining the two r a t i o s , the t h e o r e t i c a l d e t r i m e n t a l e f f e c t of the presence of n i t r a t e on P r e l e a s e (assuming p r e f e r e n t i a l use of the s u b s t r a t e i n the d e n i t r i f i c a t i o n r e a c t i o n ) can be made as f o l l o w s : Change i n P Release/N =1.75 X 1.89 = 3.31 moles P/mole N E x p r e s s i n g t h i s i n the mass c o n c e n t r a t i o n form: 3.31 (30.94/14) = 7.31 mg P/mg N which i s more than double t h a t shown f o r t h i s e xperiment i n F i g . 4.10 (a maximum of 3.0 mg P/mg N). The r e s u l t s of t h i s experiment show t h a t when the s u b s t r a t e a v a i l a b l e t o the organisms i s l i m i t i n g , the presence of i n c r e a s e d c o n c e n t r a t i o n s of n i t r a t e has an i n c r e a s i n g l y n e g a t i v e e f f e c t on P r e l e a s e . However, t h i s n e g a t i v e e f f e c t i s c l e a r l y not as g r e a t as p r e d i c t e d by d e n i t r i f i c a t i o n t h e o r y , assuming t h a t the s u b s t r a t e u t i l i z e d i n the d e n i t r i f i c a t i o n r e a c t i o n i s rendered u n a v a i l a b l e f o r P r e l e a s e . T h i s c o n f i r m s the f i n d i n g s of S e c t i o n - 8 0 -4.3.1, that the two phenomena are c l e a r l y not mutually exclusive, since the same substrate may be u t i l i z e d i n both reactions simultaneously. As i n the case of the previous experiment, i t appears that substrate that i s stored i ntracel l u l a rly under anaerobic conditions can l a t e r be u t i l i z e d i n the d e n i t r i f i c a t i o n reaction, should n i t r a t e s t i l l be present in the flask a f t e r a l l the available substrate in the supernatant i s u t i l i z e d . With regard to the aerobic P uptake i n th i s experiment, i t can be seen from Fi g . 4.9 that there were no cle a r differences observed between the various flasks and that P became l i m i t i n g a f t e r about three hours of aeration. The relationship between P release and uptake in batch tests of this nature, and i t s relevance to P removal in a continuous process reguires further investigation. -81-CHAPTER FIVE PILOT-SCALE SUBSTRATE ADDITION The o b j e c t i v e of t h e f i v e e x p e r i m e n t s d e t a i l e d i n t h i s c h a p t e r was t o d e t e r m i n e t o what e x t e n t the P r e m o v a l c h a r a c t e r i s t i c s of the p i l o t s c a l e n u t r i e n t r e moval a c t i v a t e d s l u d g e p r o c e s s c o u l d be enhanced by t h e a d d i t i o n of a sodium a c e t a t e s o l u t i o n d i r e c t l y i n t o the p r o c e s s . P h o s p h o r u s r e m o v a l e f f i c i e n c y was measured by the AP/ACOD r a t i o and t h e d r y w e i g h t p e r c e n t P c o n t e n t of t h e s l u d g e . I t was assumed t h a t the d r y w e i g h t p e r c e n t P c o n t e n t o f o r g a n i s m s n o t e x h i b i t i n g any e x c e s s b i o l o g i c a l P r e m o v a l i s 1.5% (Hoffmann and M a r a i s , 19 7 7 ) . 5.1. V a r i o u s L e v e l s of Sodium A c e t a t e A d d i t i o n t o a S i m p l i f i e d N u t r i e n t Removal A c t i v a t e d S l u d g e P r o c e s s C o n f i g u r a t i o n I n t h e e x p e r i m e n t s r e p o r t e d i n t h i s s e c t i o n t h e p r o c e s s used had a s i m p l i f i e d u n a e r a t e d / a e r a t e d c o n f i g u r a t i o n . The u n a e r a t e d f r a c t i o n made up 3 0% of t h e p r o c e s s volume and was f u r t h e r d i v i d e d i n t o two z o n e s of a p p r o x i m a t e l y e q u a l s i z e . The f i r s t u n a e r a t e d zone r e c e i v e d t h e raw sewage, t h e r e t u r n s l u d g e ( r e c y c l e r a t e 2:1 w i t h r e s p e c t t o t h e i n f l u e n t f l o w r a t e ) and t h e sodium a c e t a t e f e e d s o l u t i o n . The p r o c e s s s l u d g e age was h y d r a u l i c a l l y c o n t r o l l e d a t 20 d a y s by w a s t i n g t h e a p p r o p r i a t e volume o f mixed l i q u o r d a i l y from t h e a e r a t e d z o n e . S e c t i o n 5.1.1 s e r v e d a s the c o n t r o l p e r i o d , d u r i n g w h i c h no sodium a c e t a t e was added t o t h e b i o r e a c t o r . I n S e c t i o n s 5.1.2, 5.1.3 and 5.1.4 t h e p r o c e s s r e c e i v e d s o d i u m a c e t a t e a d d i t i o n s of 56, 86 and 112 mg/L ( e x p r e s s e d a s mg COD/L of i n f l u e n t f l o w i n g i n t o t h e -82-p r o c e s s ) , r e s p e c t i v e l y , w h i c h was f e d c o n t i n u o u s l y i n t o t h e p r o c e s s . I n f l u e n t and e f f l u e n t t o t a l P and TKN, and i n f l u e n t and added COD a n a l y s e s were done on d a i l y 2 4-hour c o m p o s i t e samples, and e f f l u e n t and COD a n a l y s i s was done on t w i c e - w e e k l y 24-hour c o m p o s i t e s a m p l e s f o r t h e e n t i r e d u r a t i o n of e a c h e x p e r i m e n t . O r t h o - P and n i t r a t e a n a l y s e s were done t w i c e w e e k l y on t h e mixed l i q u o r u s i n g f i l t e r e d g r a b s a m p l e s drawn from e a c h r e a c t o r of t h e p r o c e s s . Raw d a t a from t h i s s e r i e s of e x p e r i m e n t s i s l i s t e d i n A p p e n d i x A l and t h e mean v a l u e s of t h e r e s u l t s of e a c h s e c t i o n a r e p r e s e n t e d i n T a b l e 5.1. The r e s u l t s p r e s e n t e d i n T a b l e 5.1 f o r S e c t i o n 5.1.1 i n d i c a t e t h a t when no a c e t a t e was added t o t h e s i m p l i f i e d p r o c e s s , t h e P r e m o v a l e f f i c i e n c y was 0.0069 mg P/mg COD and t h e d r y w e i g h t p e r c e n t P c o n t e n t of t h e s l u d g e was 1.46%. T h i s v a l u e i s c l o s e t o the a c c e p t e d v a l u e f o r o r g a n i s m s n o t e x h i b i t i n g e x c e s s b i o l o g i c a l P r e m o v a l . A s l i g h t improvement i n r e m o v a l e f f i c i e n c y , from 0.0066 t o 0.0071 mg P/mg COD, was a c h i e v e d by t h e a d d i t i o n of 56 mg/L of COD t o t h e p r o c e s s i n S e c t i o n 5.1.2. However, i n S e c t i o n s 5.1.3 and 5.1.4 i n w h i c h d o s a g e s of 86 and 112 mg COD/L were added to t h e p r o c e s s , r e m o v a l e f f i c i e n c y i mproved t o a p p r o x i m a t e l y 0.01 mg P/mg COD, a n improvement of a b o u t 5 0%. The mean d r y w e i g h t p e r c e n t P c o n t e n t of t h e s l u d g e i n c r e a s e d from a r o u n d 1.5% to o v e r 2.1% f o r t h e s e two s e c t i o n s . The r e s u l t s of t h e s e two s e c t i o n s c o n f i r m t h e f i n d i n g s of S i e b r i t z e t a l . ( 1 9 8 3 ) , t h a t a c e r t a i n b a s i c minimum c o n c e n t r a t i o n o f " r e a d i l y b i o d e g r a d a b l e " s u b s t r a t e i s r e q u i r e d t o be a v a i l a b l e t o t h e o r g a n i s m s i n the a n a e r o b i c zone of t h e Table 5.1. Results of Pilot-Scale Substrate Addition Experiments Section No. Paramete r 5.1.1 (Control) 5.1.2 5.1.3 5.1.4 5.2 Influent Total P (mg/L) 4.02 3 .87 3 .32 3.06 4 .01 Ortho-P: 1st Unaerated (mg/L) 2.50 2.72 5.37 6.4.1 0.94 2nd Unaerated (mg/L) 2.76 3 .42 7.26 7.51 10.65 Aerobic (mg/L) 2.4 2 2.13 0.69 0.42 0.27 Effluent (mg/L) 2.42 2.07 0.49 0 .30 0.25 Effluent Total P (mg/L) 2.62 2.23 0.73 0.32 0.28 AP (mg/L) 1 .40 1 .64 2.59 2 .74 3 .73 % P Removal 34.8% 42.4% 78.0% 89.5% 93 .0% Influent COD (mg/L) 253 247 226 203 268 Added COD (mg/L) 0 56 86 112 39 Effluent COD (mg/L) 50 71 59 39 44 ACOD (mg/L) 203 232 253 276 263 AP/ACOD 0.0069 0.0071 0.0102 0.0099 0.0142 Influent TKN (mg/L) 21.02 20.86 21.42 18 .64 26 .00 NO3-N (mg/L): 0 .25 1st Unaerated (mg/L) 1.27 0.15 0.12 0.03 2nd Unaerated (mg/L) 0.14 0.09 0.09 0.08 0.12 Aerobic (mg/L) 7.43 4 .99 3 .87 3.88 5.93 Effluent (mg/L) 7.56 3 .72 3 .94 3.48 5.89 Effluent TKN (mg/L) - 2.23 1 .49 1.12 1 .41 % N Removal 57.0% 71.5% 74 .6% 75.3% 71.9% Process Temp. ( °C) 18.5-21.0 20.0-21.5 12.5-14.5 17 .5-21.5 10.0-16.0 Aerobic MLSS (mg/L) 27 83 2791 2732 3033 3105 Sludge Dry Wt. % P 1.46% - 2.34% 2.06% 2.5 4% -84-p r o c e s s to ensure e x c e s s b i o l o g i c a l P r e m o v a l . A c c o r d i n g to t h e i r t h e o r y , 25 mg/L of r e a d i l y b i o d e g r a d a b l e COD (measured as mg of COD/L of i n f l u e n t flow) must e n t e r the a n a e r o b i c r e a c t o r , t a k i n g i n t o a ccount the d i l u t i o n e f f e c t of any r e c y c l e s e n t e r i n g the r e a c t o r . I n S e c t i o n s 5.1.1-5.1.4 the sludge r e t u r n r e c y c l e was 2:1 w i t h r e s p e c t to the i n f l u e n t f l o w r a t e , meaning t h a t a r e a d i l y b i o d e g r a d a b l e COD c o n c e n t r a t i o n of 3X25 = 75 mg/L i n the raw sewage i s r e q u i r e d . Furthermore, the t h e o r y of S i e b r i t z e t a l . a l s o s t a t e s t h a t a p p r o x i m a t e l y 24% of the b i o d e g r a d a b l e COD ( o r about 2 0% of the t o t a l COD) p r e s e n t i n S o u t h A f r i c a n wastewaters i s i n the r e a d i l y b i o d e g r a d a b l e form. I f these f r a c t i o n s are a p p l i c a b l e to N o r t h American w a s t e w a t e r s , t h e r e s h o u l d have been a p p r o x i m a t e l y 4 0 mg/L of r e a d i l y b i o d e g r a d a b l e COD p r e s e n t i n the i n f l u e n t sewage i n these e x p e r i m e n t s and the added sodium a c e t a t e dosages s h o u l d have been supplementary to the p r e f e r r e d s u b s t r a t e c o n c e n t r a t i o n a l r e a d y p r e s e n t i n the wastewater. However, the minimum r e a d i l y b i o d e g r a d a b l e s u b s t r a t e c o n c e n t r a t i o n r e q u i r e d f o r e x c e s s b i o l o g i c a l P removal to o c c u r , as determined by S i e b r i t z e t a l . , i s based on the assumption t h a t the n i t r a t e c o n c e n t r a t i o n e n t e r i n g the a n a e r o b i c zone i s z e r o . S h o u l d any n i t r a t e e n t e r the zone, a c c o r d i n g to S i e b r i t z e t a l . ( 1983), the r e a d i l y b i o d e g r a d a b l e s u b s t r a t e i s u t i l i z e d p r e f e r e n t i a l l y i n the de n i t r i f i c a t i o n r e a c t i o n a t a r a t e of 8.6 mg COD/mg N and i s t h u s rendered u n a v a i l a b l e f o r the e x c e s s b i o l o g i c a l P removal mechanism. T h i s p r e f e r e n t i a l use of the r e a d i l y b i o d e g r a d a b l e COD i n the de n i t r i f i c a t i o n r e a c t i o n was the main m o t i v a t i o n f o r the UCT p r o c e s s c o n f i g u r a t i o n , as d e s c r i b e d -85-i n C h a p t e r Two, i n wh i c h a z e r o n i t r a t e d i s c h a r g e to t h e a n a e r o b i c r e a c t o r c a n be e n s u r e d by u s i n g t h e o p e r a t i o n a l f l e x i b i l i t y of the p r o c e s s . The b a t c h t e s t r e s u l t s p r e s e n t e d i n the p r e v i o u s c h a p t e r ( S e c t i o n 4.3) c o n f i r m t h a t t h e p r e s e n c e of n i t r a t e i n c o n c e n t r a t i o n s l i k e l y t o be f o u n d i n a n i t r i f y i n g a c t i v a t e d s l u d g e p r o c e s s i s i n h i b i t o r y to t h e a n a e r o b i c P r e l e a s e mechanism, p a r t i c u l a r l y i n c a s e s where t h e a v a i l i b i l i t y of s u b s t r a t e i s l i m i t e d . I n S e c t i o n s 5.1.2-5.1.4 t h e n i t r a t e c o n c e n t r a t i o n i n the e f f l u e n t (and t h e r e f o r e i n t h e r e t u r n s l u d g e r e c y c l e ) was i n the 3.5-5.5 mg N/L and t h e s l u d g e r e c y c l e r a t i o was m a i n t a i n e d a t 2:1 w i t h r e s p e c t to t h e i n f l u e n t f l o w . Assuming t h a t t h e s u b s t r a t e was consumed i n t h e de n i t r i f i c a t i o n r e a c t i o n a t a r a t e o f 8.6 mg COD/mg N, between 60 and 95 mg/L o f s u b s t r a t e (as COD) was r e q u i r e d t o d e n i t r i f y t h e mass of n i t r a t e e n t e r i n g the a n a e r o b i c zone v i a t h e r e t u r n s l u d g e r e c y c l e . T h e r e f o r e , i t i s c l e a r l y i m p o r t a n t t o d i s c h a r g e any s u b s t r a t e t h a t i s added t o t h e p r o c e s s i n t o a zone t h a t r e c e i v e s a z e r o n i t r a t e d i s c h a r g e . W i t h r e g a r d to b i o l o g i c a l N r e m o v a l , t h e r e s u l t s of S e c t i o n 5.1 i n d i c a t e i n c r e a s i n g N r e m o v a l e f f i c i e n c y w i t h i n c r e a s i n g sodium a c e t a t e d o s a g e s e v e n t h o u g h t h e p r o c e s s c o n f i g u r a t i o n used i n t h i s s e r i e s of e x p e r i m e n t s was n o t s p e c i f i c a l l y d e s i g n e d t o o p t i m i z e N r e m o v a l . The most p r o b a b l e e x p l a n a t i o n i s t h a t by i n c r e m e n t a l l y i n c r e a s i n g t h e a c e t a t e d o s a g e , t h e i n f l u e n t TKN/COD r a t i o was d e c r e a s e d ( v i z . 0 .083 1, 0 .0688, 0 .0687 and 0 .0592 , r e s p e c t i v e l y ) , t h e r e b y i m p r o v i n g t h e i n f l u e n t c h a r a c t e r i s t i c s f o r b i o l o g i c a l N r e m o v a l . F u r t h e r m o r e , i n a d d i t i o n t o b e i n g a - 8 6 -p r e f e r r e d s u b s t r a t e f o r e x c e s s b i o l o g i c a l P r e m o v a l , a c e t a t e i s a l s o a p r e f e r r e d s u b s t r a t e f o r b i o l o g i c a l N r e m o v a l , w i t h d e n i t r i f i c a t i o n r a t e s u s i n g a c e t a t e a s a s u b s t r a t e b e i n g m u c h h i g h e r t h a n t h o s e a c h i e v e d w i t h t h e m o r e c o m p l e x o r g a n i c s u b s t r a t e s . T h e s u p e r n a t a n t o r t h o - P c o n c e n t r a t i o n s i n t h e v a r i o u s z o n e s o f t h e p r o c e s s s h o w t h a t t h e d e g r e e o f P r e l e a s e i n t h e u n a e r a t e d z o n e i s a f u n c t i o n o f t h e a c e t a t e a v a i l a b l e t o t h e o r g a n i s m s p r e s e n t i n t h e z o n e , w i t h i n c r e a s i n g r e l e a s e b e i n g o b s e r v e d w i t h i n c r e a s i n g a c e t a t e d o s a g e s . T h i s p h e n o m e n o n c o n f i r m s t h e f i n d i n g s o f S e c t i o n 4 . 2 o f t h e p r e v i o u s c h a p t e r , t h a t t h e d e g r e e o f a n a e r o b i c P r e l e a s e i s a f u n c t i o n o f s u b s t r a t e a v a i l a b i l i t y a n d t h a t t h e r e a p p e a r s t o b e a n e x c h a n g e p h e n o m e n o n t h a t o c c u r s b e t w e e n t h e a c e t a t e a n d t h e p h o s p h a t e m o l e c u l e s u n d e r a n a e r o b i c c o n d i t i o n s . T h e r e s u l t s o f S e c t i o n 5 . 1 , t h e r e f o r e , c o n f i r m t h e f i n d i n g s o f m a n y r e s e a r c h e r s ( B a r n a r d ( 1 9 7 4 , 19 7 5 , 19 7 6 ) , R a b i n o w i t z a n d M a r a i s ( 1 9 8 0 ) a n d S i e b r i t z e t a l . ( 1 9 8 3 ) ) t h a t t h e P r e m o v a l c h a r a c t e r i s t i c s o f t h e a c t i v a t e d s l u d g e p r o c e s s a r e i m p r o v e d w i t h i n c r e a s i n g d e g r e e s o f a n a e r o b i c P r e l e a s e . 5 . 2 . T h e E f f e c t o f F e e d i n g S o d i u m A c e t a t e t o a Z o n e t h a t R e c e i v e s a Z e r o N i t r a t e D i s c h a r g e T h e o b j e c t i v e o f t h i s s e c t i o n w a s t o d e t e r m i n e t o w h a t e x t e n t t h e P r e m o v a l c h a r a c t e r i s t i c s o f a s i m p l i f i e d n u t r i e n t r e m o v a l a c t i v a t e d s l u d g e p r o c e s s r e c e i v i n g s o d i u m a c e t a t e c a n b e i m p r o v e d b y d i s c h a r g i n g t h e a d d e d s u b s t r a t e t o a z o n e t h a t r e c e i v e d n o i n f l u e n t n i t r a t e c o n c e n t r a t i o n . T o t h i s e n d t h e s o d i u m a c e t a t e s o l u t i o n w a s f e d i n t o t h e s e c o n d u n a e r a t e d z o n e , r a t h e r t h a n t h e -87-f i r s t , o f a p r o c e s s h a v i n g i t s u n a e r a t e d zone a t the head e n d o f the p r o c e s s f u r t h e r d i v i d e d i n t o two z o n e s of e q u a l s i z e . I n t h i s way, i t was r e a s o n e d , c o m p l e t e de n i t r i f i c a t i o n w o u l d o c c u r i n the f i r s t u n a e r a t e d zone making use of t h e r e a d i l y b i o d e g r a d a b l e COD and t h e more complex o r g a n i e s p r e s e n t i n t h e in c o m i n g w a s t e w a t e r , and t h e n i t r a t e c o n c e n t r a t i o n e n t e r i n g t h e s e c o n d u n a e r a t e d zone would, t h e r e f o r e , be z e r o . T h i s w o u l d f a c i l i t a t e a more e f f i c i e n t use of t h e added s u b s t r a t e , a s a l l of i t would be a v a i l a b l e f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism. I n a d d i t i o n , t h e f o l l o w i n g two c h a n g e s were made t o the p r o c e s s c o n f i g u r a t i o n - t h e u n a e r a t e d volume f r a c t i o n was i n c r e a s e d t o 4 0% b u t was s t i l l e q u a l l y d i v i d e d i n t o two z o n e s of a p p r o x i m a t e l y e q u a l s i z e , and t h e s l u d g e r e c y c l e r a t i o was d e c r e a s e d from 2:1 t o 1:1 i n o r d e r t o m i n i m i z e t h e mass of n i t r a t e b e i n g r e c y c l e d t o t h e u n a e r a t e d z o n e . The r e s u l t s of t h i s e x p e r i m e n t a r e a l s o i n c l u d e d i n T a b l e 5.1 f o r t h e p u r p o s e s o f c o m p a r i s o n . The r e s u l t s o f t h i s e x p e r i m e n t c l e a r l y show t h a t a s i g n i f i c a n t l y more e f f i c i e n t use was made of t h e added a c e t a t e s o l u t i o n by f e e d i n g i t i n t o a zone t h a t r e c e i v e d l i t t l e o r no i n f l u e n t n i t r a t e . A c o n t i n u o u s s u b s t r a t e a d d i t i o n of 39 mg/L ( a s mg COD/L of i n f l u e n t f l o w i n g i n t o t h e p r o c e s s ) i n t o t h e s e c o n d u n a e r a t e d zone r e s u l t e d i n an o v e r a l l P r e m o v a l e f f i c i e n c y of 0.0142 mg P/mg COD. T h i s l e v e l of s u b s t r a t e a d d i t i o n i s a b o u t 40% l e s s t h a n the dosage u s e d i n S e c t i o n 5.1.2 (56 mg COD/L) where no s i g n i f i c a n t improvement i n P r e m o v a l e f f i c i e n c y was a c h i e v e d by s u b s t r a t e a d d i t i o n . The r e m o v a l e f f i c i e n c y a c h i e v e d - 8 8 -i n t h i s e x p e r i m e n t i s more t h a n 100% g r e a t e r t h a n t h a t a c h i e v e d i n t h e c o n t r o l , ( S e c t i o n 5.1.1) and 4 0% g r e a t e r t h a n t h a t a c h i e v e d i n the two h i g h e r s u b s t r a t e a d d i t i o n e x p e r i m e n t s , r e p o r t e d i n S e c t i o n s 5.1.3 and 5.1.4. W i t h r e g a r d t o b i o l o g i c a l N r e m o v a l , t h e N r e m o v a l e f f i c i e n c y of S e c t i o n 5.2 i s s i m i l a r t o t h a t a c h i e v e d i n S e c t i o n 5.1.2 i n which a c o m p a r a b l e a c e t a t e dosage was f e d i n t o t h e p r o c e s s . However, i n t h i s e x p e r i m e n t t h e e f f l u e n t n i t r a t e c o n c e n t r a t i o n was a p p r o x i m a t e l y 6 0% h i g h e r t h a n t h a t i n t h e o t h e r t h r e e e x p e r i m e n t s i n w hich t h e p r o c e s s r e c e i v e d a c e t a t e a d d i t i o n . T h e r e a r e two p o s s i b l e e x p l a n a t i o n s f o r t h e i n c r e a s e d e f f l u e n t n i t r a t e c o n c e n t r a t i o n . F i r s t l y , t h e mean i n f l u e n t TKN c o n c e n t r a t i o n i n t h i s e x p e r i m e n t was a p p r o x i m a t e l y 3 0% h i g h e r t h a n i n the o t h e r t h r e e e x p e r i m e n t s and s e c o n d l y , a l o w e r mass of n i t r a t e was b e i n g r e c y c l e d t o t h e u n a e r a t e d zone v i a t h e r e d u c e d s l u d g e r e c y c l e , meaning t h a t the de n i t r i f i c a t i o n c a p a c i t y of t h e p r o c e s s was n o t as e f f i c i e n t l y u t i l i z e d . The o r t h o - P c o n c e n t r a t i o n p r o f i l e s o f t h e v a r i o u s z o n e s p r e s e n t e d i n T a b l e 5.1 c o n f i r m t h e more e f f i c i e n t use o f t h e added a c e t a t e i n t h e p r o c e s s f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism. The mass o f P r e l e a s e d by the end of t h e u n a e r a t e d zone was g r e a t e s t i n t h i s e x p e r i m e n t i n s p i t e o f t h e f a c t t h a t t h e added a c e t a t e was l o w e s t i n t h i s e x p e r i m e n t and a l l of t h i s r e l e a s e t o o k p l a c e i n the s e c o n d u n a e r a t e d zone o n l y . A l l o f t h e f a c t o r s o u t l i n e d above c l e a r l y d e m o n s t r a t e t h e a d v a n t a g e o f f e e d i n g any a d d i t i o n a l s u b s t r a t e , w h e t h e r i t be i n t h e s y n t h e t i c form o r -89-g e n e r a t e d o n - s i t e by p r i m a r y s l u d g e f e r m e n t a t i o n , d i r e c t l y i n t o an u n a e r a t e d zone t h a t r e c e i v e s no i n f l u e n t n i t r a t e . However, a d d i t i o n a l r e s e a r c h i s s t i l l r e q u i r e d t o d e t e r m i n e what p e r c e n t a g e of m i c r o - o r g a n i s m s i n v o v l e d i n t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism a r e a l s o c a p a b l e of d e n i t r i f i c a t i o n . T h i s w o u l d f a c i l i t a t e q u a n t i f i c a t i o n of t h e r e l a t i v e mass of s u b s t r a t e u t i l i z e d f o r e x c e s s b i o l o g i c a l P r e m o v a l o n l y , f o r d e n i t r i f i c a t i o n o n l y , and i n b o t h mechanisms s i m u l t a n e o u s l y . -90-CHAPTER SIX PRIMARY SLUDGE FERMENTATION RESULTS In t h i s chapter the r e s u l t s of a p i l o t s c a l e study i n t o s h o r t - c h a i n v o l a t i l e f a t t y a c i d (VFA) p r o d u c t i o n by primary sludge fermentation are d e t a i l e d . The p r i n c i p l e o b j e c t i v e of the study was to determine the amount of VFA's that can reasonably be produced from primary sludge, and the d i s t r i b u t i o n of the a c i d s that make up the p r o d u c t i o n . The three main o p e r a t i o n a l parameters c o n t r o l l i n g anaerobic fermentation, sludge age o r mean s o l i d s r e t e n t i o n time, temperature and pH, were i n v e s t i g a t e d . S e c t i o n 6.1 d e s c r i b e s a d e t a i l e d study i n t o the e f f e c t of sludge age i n the 2.5-10 day range a t ambient temperatures between 16 and 20°C. S e c t i o n s 6.2 and 6.3 d e s c r i b e a somewhat l e s s d e t a i l e d study i n t o the e f f e c t s of temperature and pH. The fermentation u n i t used i n t h i s s e r i e s of experiments c o n s i s t e d of a 5 40 L primary c l a r i f i e r and a two-stage anaerobic sludge fermenter with a t o t a l volume of 1000 L. Primary sludge was pumped on a h a l f - h o u r l y c y c l e from the bottom of the primary c l a r i f i e r i n t o the f i r s t fermentation r e a c t o r . The underflow pumping rate was r e g u l a t e d between 6 and 10% of the i n f l u e n t flow r a t e by a d j u s t i n g the l e n g t h of the "ON" c y c l e of the primary sludge pump. The primary sludge COD l o a d i n g e n t e r i n g the fermenter was c a l c u l a t e d on the b a s i s of a COD mass balance on the primary c l a r i f i e r , because of the v a r i a t i o n i n the organic s t r e n g t h of the primary sludge over the course of the day and the d i f f i c u l t i e s a s s o c i a t e d with measuring the COD value of the -91-p r i m a r i l y p a r t i c u l a t e m a t e r i a l . The c a l c u l a t i o n was b a s e d on t h e d i f f e r e n c e between the mass of COD e n t e r i n g t h e p r i m a r y c l a r i f i e r i n the raw sewage and t h a t l e a v i n g t h e c l a r i f i e r v i a the s e t t l e d sewage, i . e . i t was assumed t h a t t h e r e was no COD d e s t r u c t i o n i n t h e p r i m a r y c l a r i f i e r and t h a t a l l the COD e n t e r i n g t h e c l a r i f i e r l e f t e i t h e r v i a the s e t t l e d sewage o r t h e p r i m a r y s l u d g e . Raw i n f l u e n t and s e t t l e d sewage COD a n a l y s i s was done on d a i l y 24-hour c o m p o s i t e s a m p l e s and VFA a n a l y s i s was done on the f i l t e r e d s u p e r n a t a n t of g r a b s a m p l e s drawn d a i l y from t h e f e r m e n t a t i o n r e a c t o r s . VFA p r o d u c t i o n was compared on t h e b a s i s o f a y i e l d f a c t o r w h i c h was d e f i n e d a s the r a t i o of t h e d a i l y mean t o t a l VFA p r o d u c e d ( a s HAc) p e r u n i t mass of p r i m a r y s l u d g e ( a s COD) e n t e r i n g t h e f e r m e n t e r f o r e a c h s t u d y p e r i o d . 6.1. The E f f e c t of S l u d g e Age on VFA P r o d u c t i o n The o b j e c t i v e of t h i s s e r i e s of e x p e r i m e n t s was t o i n v e s t i g a t e t h e e f f e c t s of s l u d g e age on VFA p r o d u c t i o n . An a t t e m p t was made t o m a i n t a i n the f e r m e n t e r t e m p e r a t u r e c l o s e to 2 0°C by t h e use o f s p a c e h e a t i n g d u r i n g t h e w i n t e r months. The pH was n o t c o n t r o l l e d i n any way, e x c e p t t h a t a b o u t 100 mg/L o f a l k a l i n i t y ( a s CaC03) was added t o t h e raw i n f l u e n t d a i l y i n o r d e r t o improve i t s b u f f e r i n g c a p a c i t y and t h u s m a i n t a i n t h e pH of t h e a c t i v a t e d s l u d g e p r o c e s s e s above 6.5. D u r i n g t h e f i r s t t h r e e e x p e r i m e n t s the s l u d g e age was r e g u l a t e d a t 2.5, 3.5 and 5.0 d a y s , r e s p e c t i v e l y , by a d j u s t i n g t h e pumping r a t e from t h e p r i m a r y c l a r i f i e r t o the f e r m e n t e r , w i t h b o t h f e r m e n t a t i o n r e a c t o r s o p e r a t i n g u n d e r c o m p l e t e l y mixed c o n d i t i o n s ( i . e . s l u d g e age e g u a l t o the h y d r a u l i c r e t e n t i o n t i m e ) . I n t h e f o u r t h -92-experiment a secondary c l a r i f i e r , from which settled, fermented sludge was returned to the f i r s t fermentation reactor at a recycle rate of 2:1, was i n s t a l l e d . In this experiment the sludge age was hydraulically controlled by wasting the appropriate volume of mixed liq u o r from the second fermentation reactor. The operational parameters and results of the four experiments are presented in Table 6.1 and the raw data are l i s t e d in Appendix A2. A l l of the values reported in Table 6.1 are the mean values for each experiment, with the exception of pH which i s reported as the median values for each experiment. The VFA results presented in Table 6.1 show the largest percentage of acid produced for a l l sludge ages to be i n the acetic acid form, which comprised 57%, 56%, 5 3% and 56%, respectively, of the production. The second major VFA form produced was propionic acid which made up 4 1%, 4 3%, 4 3% and 4 2%. of the acid production. In each case the balance of the acid produced was in the butyric acid form. No other short chain VFA's were present in detectable concentrations (>3 mg/L as HAc, using gas chromatography) in the fermenter supernatant. The fermenter sludge age did not appear to s i g n i f i c a n t l y affect either the y i e l d of VFA produced from the primary sludge or the d i s t r i b u t i o n of the various component acids in the 2.5-10.0 day range. Optimum yields were attained in the 3.5 and 5.0 sludge age experiments, with yields being s l i g h t l y greater than 0.09 mg HAc/mg COD of primary sludge. However, even the lower acid production in the 2.5 day sludge age experiment could possibly be explained by the s i g n i f i c a n t l y lower mean fermenter operating -93-T a b l e 6.1. The E f f e c t of S l u d g e Age on VFA P r o d u c t i o n from P r i m a r y S l u d g e ( S e c t i o n 6.1) S e c t i o n No. Paramete r 6.1.1 6.1.2 6.1.3 6.1.4 S l u d g e Age ( d a y s ) 2.5 3.5 5.0 10.0 I n f l u e n t (mg COD/L) 277 250 245 351 S e t t . Sewage ( " ) 179 140 151 187 P r i m . S l u d g e ( " ) 1142 1794 1718 1823 U n d e r f l o w r a t e (% o f 10.0% 6 .67% 6.0% 10.0% raw sewage' f l o w r a t e ) T e m p e r a t u r e ( ° C ) : Fe rm. 1 15.7 18 .1 20.8 19 .7 Fe rm. 2 15.7 19.6 20.8 20.9 MLSS (mg/L): Fe rm. 1 1344 1961 1358 2310 Fe rm. 2 2460 2139 2433 2432 Median pH: Ferm. 1 6.05 5.90 5.60 6.10 Fe rm. 2 5 .85 5 .60 5.15 6 .00 VFA P r o d u c t i o n (mg/L) F e r m e n t e r 1: A c e t i c a c i d ( a s HAc) 27.6 61.8 60.7 69.0 P r o p i o n i c a c i d (") 14.7 43.9 44.6 47.3 B u t y r i c a c i d (") 0.5 0.7 2.8 3 .4 T o t a l a c i d (") 42.8 106 .4 108.1 119.7 F e r m e n t e r 2: A c e t i c a c i d ( a s HAc) 51.0 90.9 85.0 79.0 P r o p i o n i c a c i d (") 37.4 70.1 69.2 59.1 B u t y r i c a c i d ( " ) 1.8 1.5 5.5 4.2 T o t a l a c i d (") 90.2 162.5 159.7 141.7 F e r m e n t e r C l a r i f i e r : T o t a l a c i d ( as HAc) - - - 151 .0 Y i e l d (mg HAc/mg COD) 0.0790 0.0906 0.0930 0.0828 -94-o o temperature (15.7 vs about 20 C) during this period. In general, the median pH values for a l l the experiments were in the 5.1-6.1 range, with the lower values being attained where VFA production was most e f f i c i e n t . The pH dropped by between 0.25 and 0.55 pH units between the two fermentation reactors in the f i r s t three experiments, in which there was no internal recycle. In the fourth experiment, where the fermented sludge was recycled from the c l a r i f i e r to the f i r s t fermentation reactor, the median pH dropped by only 0.10 pH units between the two reactors. I t should be noted that the MLSS concentration difference between the two reactors was also smallest in the 10 day sludge age experiment, probably also as a result of the sludge recycling. The VFA yields achieved in these experiments appear to be below both the sodium acetate addition requirements found i n the previous chapter, and the "readily biodegradable COD" reguirement in the activated sludge process influent stream according to Si e b r i t z et a l . ( 1982) ( i . e . 25 mg COD/L entering the anaerobic reactor). One possible way of improving fermenter e f f i c i e n c y i s to increase the operating temperature of the fermenter. Microbiologists point to a doubling of microbial a c t i v i t y for every 5-10°C increase in temperature for psychrophiles and, therefore, far greater VFA yields may be expected at the higher temperatures. In addition, the v i a b i l i t y of fermenter pH control with the view to maximizing VFA production also requires examination. There are indications in the l i t e r a t u r e that the uncontrolled pH range at which this experiment was conducted (5.1-6.1) may prove not to be the optimal range for the -95-acid-forming bacteria. For example, Borchardt (1970) found that optimum acid production occurs at a pH of 6.95, with production dropping off s i g n i f i c a n t l y on either side of t h i s optimum value. 6.2. The Effect of Temperature on VFA Production The objective of this experiment was to determine to what extent the operating temperature of the fermenter a f f e c t s the VFA production e f f i c i e n c y . As a result of the i n f l e x i b i l i t y of the p i l o t plant, i t was only possible to raise the fermenter temperature to about 22°C using space heating. For this reason, i t was decided to do a cold temperature study over the winter months. The study period lasted approximately two months during which the fermenter was operated at a sludge age of 3.5 days with a mean fermenter temperature of 12.7°C. The results of the experiment are, therefore, compared with the re s u l t s of Section 6.1.2 in which the sludge age was also kept at 3.5 days, but where the process temperature was raised to around 19 °c using space heating. The raw data from this experiment are shown in Appendix A2 and the mean experimental r e s u l t s are presented together with those of Section 6.1.2, which served as the control for this experiment, in Table 6.2. The results presented in Table 6.2 indicate that when the mean operating temperature of the fermenter at a sludge age of 3.5 days was lowered by 6°C, the resultant drop in VFA production e f f i c i e n c y was about 20%, the y i e l d dropping from 0.0906 to 0.0732 mg HAc/mg COD. This drop in e f f i c i e n c y i s s i g n i f i c a n t l y less than that predicted by microbiologists for general anaerobic -96-Table 6.2. The E f f e c t of Temperature on VFA P r o d u c t i o n from Primary Sludge ( S e c t i o n 6.2) Parameter C o n t r o l Expe riment Sludge Age (days) 3.5 3 .5 I n f l u e n t (mg COD/L) 250 265 S e t t . Sewage ( " ) 140 147 Prim. Sludge ( " ) 1794 1910 Underflow rate (% of 6 .67% 6 .67% raw sewage flow rate) Temperature ( °C ) : Fe rm. 1 18.1 12.7 Ferm. 2 19.6 12.7 MLSS (mg/L): Ferm. 1 1961 316 6 Fe rm. 2 2139 3647 Median pH: Ferm. 1 5.90 5.80 Fe rm. 2 5.60 5 .65 VFA Production (mg/L) Fermenter 1: A c e t i c a c i d (as HAc) 61.8 52.5 P r o p i o n i c a c i d (") 43.9 34.1 B u t y r i c a c i d (" ) 0.7 0.7 T o t a l a c i d (") 106 .4 87.3 Fermenter 2: A c e t i c a c i d (as HAc) 90 .9 77.8 P r o p i o n i c a c i d (") 70.1 60.7 B u t y r i c a c i d (" ) 1.5 1.2 T o t a l a c i d (") 162.5 139.7 Y i e l d (mg HAc/mg COD) 0.0906 0.0732 -97-a c t i v i t y . However, a d e t a i l e d study of the e f f e c t s of o p e r a t i n g temperatures g r e a t e r than 20°C i s s t i l l r e q u i r e d . In a d d i t i o n , the economics of o p e r a t i n g a primary sludge fermenter i n the m e s o p h i l i c temperature range (around 37°C), a temperature range commonly used i n the o p e r a t i o n of anaerobic sludge d i g e s t e r s , a l s o warrants c l o s e r examination as the c o s t s i n v o l v e d may prove to be p r o h i b i t i v e . The lower fermenter o p e r a t i n g temperature had no s i g n i f i c a n t e f f e c t on the d i s t r i b u t i o n of the component a c i d s making up the VFA p r o d u c t i o n , with a c e t i c and p r o p i o n i c a c i d s making up about 5 6% and 4 3%, r e s p e c t i v e l y , a t both temperatures. 6.3. The E f f e c t of pH on VFA P r o d u c t i o n In t h i s experiment the o p e r a t i n g pH of the fermenter r e a c t o r s was r a i s e d to around n e u t r a l i t y , i n o r d e r to determine i f t h i s would enhance the VFA p r o d u c t i o n . I t was reasoned t h a t r a i s i n g the pH might p o s s i b l y improve the VFA y i e l d f o r the f o l l o w i n g two reasons: f i r s t l y , a pH of 7.0 may, i n f a c t , be a b e t t e r pH f o r the acid-forming b a c t e r i a , as i n d i c a t e d i n the l i t e r a t u r e (Borchardt, 1970), and the u n c o n t r o l l e d pH approach of S e c t i o n 6.1 may have r e s u l t e d i n sub-optimal c o n d i t i o n s due to product i n h i b i t i o n ; secondly, the pK v a l u e s f o r a c e t i c and b u t y r i c a c i d are 4.76 and 4.83 a t 25 °C, r e s p e c t i v e l y , meaning t h a t a t the hi g h e r pH values, a s i g n i f i c a n t l y s m a l l e r f r a c t i o n of the a c i d s produced are i n the molecular form from which v o l a t i l i z a t i o n i s p o s s i b l e , i . e . the produced VFA i s l a r g e l y i n the more s t a b l e s a l t form i n which i t can be fed d i r e c t l y i n t o the subsequent a c t i v a t e d sludge process. In t h i s experiment the fermenter was once again operated a t a 3.5 day sludge age and a mean -98-temperature of around 20°c so t h a t , as i n the case of the pre v i o u s experiment, the r e s u l t s of the experiment o u t l i n e d i n S e c t i o n 6.1.2 served as the c o n t r o l f o r t h i s experiment. Because automated pH c o n t r o l apparatus was not a v a i l a b l e f o r use i n t h i s experiment, the fermenter pH was adjus t e d manually by the a d d i t i o n of sodium hydroxide p e l l e t s to each fermentation r e a c t o r . The pH value of each r e a c t o r was recorded immediately before the sodium hydroxide a d d i t i o n and again about 15 minutes l a t e r . The raw data f o r t h i s experiment are l i s t e d i n Appendix A2 and the mean r e s u l t s are presented i n Table 6.3. The pH r e s u l t s are presented i n the form of a "low" and a "high" reading f o r each day, i n d i c a t i n g the pH value immediately before and a f t e r the sodium hydroxide a d d i t i o n , r e s p e c t i v e l y . The r e s u l t s of t h i s experiment, presented i n Table 6.3, i n d i c a t e t h at r a i s i n g the pH of a primary sludge fermenter ope r a t i n g a t a 3.5 day sludge age r e s u l t e d i n a mean drop i n VFA pr o d u c t i o n y i e l d of about 30%, from 0 .0906 to 0 .0633 mg HAc/mg COD of primary sludge. T h i s r e s u l t i s i n s p i t e of the f a c t that the o p e r a t i o n a l parameters of the experimental and c o n t r o l p e r i o d s were s i m i l a r except that the mean temperature was about 1 °C higher i n the experimental p e r i o d . Examination of the VFA pr o d u c t i o n raw data i n Appendix A2 p o i n t s to an i n t e r e s t i n g phenomenon i n t h i s experiment. The c o n c e n t r a t i o n of VFA's produced i n the f i r s t three weeks of the experiment was around 200 mg/L of a c i d (as HAc), i n d i c a t i n g t h a t there was some i n i t i a l p e r i o d of improved p r o d u c t i o n . However, i n the f i n a l four weeks of the experiment, the VFA p r o d u c t i o n dropped to around 80 mg/L, - 9 9 -T a b l e 6 . 3 . T h e E f f e c t o f p H o n VFA P r o d u c t i o n f r o m P r i m a r y S l u d g e ( S e c t i o n 6 . 3 ) P a r a m e t e r C o n t r o l E x p e r i m e n t S l u d g e A g e ( d a y s ) 3 . 5 3 . 5 I n f l u e n t (mg C O D / L ) 2 5 0 2 8 2 S e t t . S e w a g e ( " ) 1 4 0 1 6 5 P r i m . S l u d g e ( " ) 1 7 9 4 1 9 2 0 U n d e r f l o w r a t e (% o f 6 . 6 7 % 6 . 6 7 % r a w s e w a g e f l o w r a t e ) T e m p e r a t u r e ( ° c ) : Fe r m . 1 1 8 . 1 1 8 . 9 Fe r m . 2 1 9 . 6 2 0 . 8 MLSS ( m g / L ) : Fe r m . 1 1 9 6 1 1 3 5 7 Fe r m . 2 2 1 3 9 1 5 1 3 M e d i a n p H : L o w / H i g h Fe r m . 1 5 . 9 0 6 . 7 5 / 7 . 0 5 Fe r m . 2 5 . 6 0 6 . 8 5 / 7 . 3 0 VFA P r o d u c t i o n ( m g / L ) F e r m e n t e r 1 : A c e t i c a c i d ( a s H A c ) 6 1 . 8 4 6 . 2 P r o p i o n i c a c i d ( " ) 4 3 . 9 2 9 . 4 B u t y r i c a c i d ( " ) 0 . 7 1 . 0 T o t a l a c i d ( " ) 1 0 6 . 4 7 6 . 6 F e r m e n t e r 2 : A c e t i c a c i d ( a s H A c ) 9 0 . 9 6 6 . 7 P r o p i o n i c a c i d ( " ) 7 0 . 1 5 0 . 8 B u t y r i c a c i d ( " ) 0 . 7 4 . 0 T o t a l a c i d ( " ) 1 6 2 . 5 1 2 1 . 5 Y i e l d (mg H A c / m g COD) 0 . 0 9 0 6 0 . 0 6 3 3 -100-r e s u l t i n g i n a mean VFA p r o d u c t i o n f o r t h e e x p e r i m e n t o f 121.5 mg/L. T h i s l a r g e v a r i a t i o n i n p r o d u c t i o n d u r i n g t h e c o u r s e of the e x p e r i m e n t may have been t h e r e s u l t o f t h e u n s t a b l e o p e r a t i n g c o n d i t i o n s i n the f e r m e n t e r i t s e l f , p a r t i c u l a r l y w i t h r e g a r d t o the pH c o n t r o l . B e c a u s e the pH was o n l y a d j u s t e d once d a i l y , a s op p o s e d t o b e i n g c o n s t a n t l y m a i n t a i n e d a t a g i v e n v a l u e , t h e pH of the f e r m e n t a t i o n r e a c t o r s was i n a c o n s t a n t s t a t e of f l u x , i . e . i t was r a i s e d by a b o u t 0.5 pH u n i t s once d a i l y and t h e n a l l o w e d t o dr o p by t h a t amount d u r i n g t h e f o l l o w i n g 24 h o u r s . I t i s p o s s i b l e t h a t t h e c o n s t a n t l y c h a n g i n g pH e n v i r o n m e n t i t s e l f was r e s p o n s i b l e f o r t h e d i m i n i s h e d VFA p r o d u c t i o n and o u t w e i g h e d any p o s s i b l e b e n e f i t o f t h e mean i n c r e a s e i n t h e f e r m e n t e r pH. F o r t h i s r e a s o n , an a d d i t i o n a l p i l o t - s c a l e s t u d y w i t h a u t o m a t e d pH c o n t r o l i n the f e r m e n t a t i o n r e a c t o r s i s s t i l l r e q u i r e d i n o r d e r t o a c c u r a t e l y d e t e r m i n e t h e p o t e n t i a l f o r improved VFA p r o d u c t i o n u s i n g pH c o n t r o l . W i t h r e g a r d t o t h e d i s t r i b u t i o n o f the component a c i d s , t h e r e a p p e a r s t o be v e r y l i t t l e d i f f e r e n c e i n the a c i d p r o d u c t i o n e x c e p t t h a t t h e b u t y r i c a c i d component i n c r e a s e d from 1% t o a r o u n d 3%. However, i t i s n o t a n t i c i p a t e d t h a t t h i s w i l l have a m a j o r e f f e c t on t h e u s e f u l n e s s of t h e VFA as a s u b s t r a t e i n t h e a c t i v a t e d s l u d g e p r o c e s s . -101-CHAPTER SEVEN THE USE OF PRIMARY SLUDGE FERMENTATION IN THE ACTIVATED SLUDGE PROCESS The p r i n c i p l e o b j e c t i v e of the e x p e r i m e n t s d e s c r i b e d i n t h i s c h a p t e r was to determine t o what e x t e n t the P removal c h a r a c t e r i s t i c s of the n u t r i e n t removal a c t i v a t e d s l u d g e p r o c e s s can be enhanced by the use of p r i m a r y sludge f e r m e n t a t i o n . T h i s s e r i e s of e x p e r i m e n t s was conducted a t the p i l o t - s c a l e w i t h the f e r m e n t e r i n c o r p o r a t e d i n t o the a c t i v a t e d s l u d g e p r o c e s s . The raw sewage flowed i n t o the p r i m a r y c l a r i f i e r , from which the s e t t l e d sewage passed i n t o the head end of the p r o c e s s . The p r i m a r y sludge was pumped i n t o the two-stage f e r m e n t e r , which was o p e r a t e d a t a sludge age of 10 days w i t h the use of the f e r m e n t e r secondary c l a r i f i e r (See Chapter S i x , S e c t i o n 6.1.4). The e f f l u e n t from the f e r m e n t e r c l a r i f i e r then f l o w e d i n t o the a n a e r o b i c zone (one t h a t r e c e i v e d l i t t l e o r no incoming n i t r a t e ) of the p r o c e s s so t h a t e f f i c i e n t use of the VFA's p r e s e n t i n the f e r m e n t e r l i q u o r c o u l d be made i n the e x c e s s b i o l o g i c a l P removal mechanism (See Chapter F i v e , S e c t i o n 5.2) r a t h e r than the s u b s t r a t e b e i n g u t i l i z e d i n the d e n i t r i f i c a t i o n r e a c t i o n . The p r o c e s s s c h e m a t i c s used a r e shown i n F i g s . 7.1 and 7.2. Fermenter and a c t i v a t e d s l u d g e p r o c e s s o p e r a t i o n and sampling was done u s i n g s i m i l a r methodologies to those d e s c r i b e d i n C h a p t e r s S i x and F i v e , r e s p e c t i v e l y . I n each s e c t i o n the r e s u l t s of the performance of the p r o c e s s w i t h the i n c o r p o r a t i o n of p r i m a r y sludge f e r m e n t a t i o n i n t o the d e s i g n are compared w i t h those f o r a -102-s i m i l a r process c o n f i g u r a t i o n that r e c e i v e d raw sewage on l y and, t h e r e f o r e , served as the c o n t r o l . The mean P removal e f f i c i e n c y was measured by the AP/ACOD r a t i o ( i . e . the mass of P removed per u n i t mass of COD removed from the incoming wastewater) of the combined fermenter and a c t i v a t e d sludge process i n the experimental p e r i o d s . The degree to which excess b i o l o g i c a l P removal was o c c u r r i n g i n the a c t i v a t e d sludge process was determined by the extent to which the dry weight percentage P content of sludge drawn from the a e r o b i c zone of the process exceeded 1.5%, the accepted P content of organisms not s t o r i n g excess polyphosphate. 7.1. The Use of the Fermenter i n the S i m p l i f i e d N u t r i e n t Removal A c t i v a t e d Sludge Process The o b j e c t i v e of t h i s s e c t i o n was to determine to what extent the P removal c h a r a c t e r i s t i c s of a s i m p l i f i e d unaerated/aerated process can be enhanced by the use of primary sludge fermentation. Schematic diagrams of the process c o n f i g u r a t i o n s used i n the c o n t r o l and experimental p e r i o d s are shown i n F i g . 7.1. 7.1.1. C o n t r o l The process c o n f i g u r a t i o n used and the r e s u l t s of t h i s experiment are those of S e c t i o n 5.1 (Chapter Five) f o r the s i m p l i f i e d unaerated/aerated n u t r i e n t removal process that r e c e i v e d no sodium acetate a d d i t i o n . The process had a 30% unaerated volume f r a c t i o n which was f u r t h e r d i v i d e d i n t o two zones of approximately equal s i z e . The f i r s t unaerated zone r e c e i v e d the raw i n f l u e n t and the r e t u r n sludge r e c y c l e which had a r e c y c l e -103-CONTROL U N A E R A T E D A E R A T E D S E C O N D A R Y Z O N E Z O N E CLARIFIER I N F L U E N T V7 E F F L U E N T \ V i : i i O O O O R E T U R N S L U D G E 2= 1 •« EXPERIMENT P R I M A R Y C L A R I F I E R I N F L U E N T U N A E R A T E D Z O N E A E R A T E D Z O N E S E C O N D A R Y C L A R I F I E R V V V V s | : £ • • • • O O O O E F F L U E N T 10% R E T U R N S L U D G E 2* y T W O S T A G E P R I M A R Y S L U D G E F E R M E N T E R E Q U I P P E D WITH S E C O N D A R Y C L A R I F I E R F i g u r e 7.1. The use of primary sludge fermentation i n the s i m p l i f i e d n u t r i e n t removal process - C o n t r o l and Experimental process c o n f i g u r a t i o n s -104-r a t i o o f 2:1 w i t h r e s p e c t t o the i n f l u e n t f l o w r a t e . The raw d a t a f o r t h i s e x p e r i m e n t a r e shown i n A ppendix A l ( S e c t i o n 5.1.1) and the mean r e s u l t s a r e p r e s e n t e d i n T a b l e 7.1. The r e s u l t s o f E x p e r i m e n t 7.1.1 i n d i c a t e t h a t no e x c e s s b i o l o g i c a l P r e m o v a l t o o k p l a c e i n the s i m p l i f i e d n u t r i e n t r e m o v a l p r o c e s s . The AP/ACOD r a t i o was 0 .0069 w h i l e t h e mean d r y w e i g h t p e r c e n t P c o n t e n t o f t h e s l u d g e drawn from t h e a e r o b i c zone o f the p r o c e s s was 1.46%. F u r t h e r m o r e , no P r e l e a s e took p l a c e i n t h e a n a e r o b i c zone o f the p r o c e s s . T h i s r e s u l t i s n o t u n e x p e c t e d i n terms of t h e p r e s e n t u n d e r s t a n d i n g o f t h e p r e r e q u i s i t e s f o r e x c e s s b i o l o g i c a l P r e m o v a l , a s i t c a n be assumed t h a t l i t t l e o r none o f the s i m p l e s u b s t r a t e r e q u i r e d f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism was a v a i l a b l e to t h e o r g a n i s m s i n the s e c o n d u n a e r a t e d zone, the o n l y zone n o t r e c e i v i n g a h i g h i n f l u e n t n i t r a t e c o n c e n t r a t i o n . 7.1.2. E x p e r i m e n t In the e x p e r i m e n t a l p e r i o d , the p r i m a r y s l u d g e f e r m e n t e r was i n c o r p o r a t e d i n t o the d e s i g n of t h e s i m p l i f i e d n u t r i e n t r e m o v a l p r o c e s s (See F i g u r e 7 . 1 ) . The f i r s t u n a e r a t e d zone r e c e i v e d t h e s e t t l e d sewage and t h e r e t u r n s l u d g e r e c y c l e , whose r e c y c l e r a t i o was r e d u c e d t o 1:1 w i t h r e s p e c t t o t h e i n f l u e n t f l o w r a t e , and t h e s e c o n d u n a e r a t e d zone r e c e i v e d t h e f e r m e n t e r e f f l u e n t . I t was r e a s o n e d t h a t a l l o f t h e n i t r a t e e n t e r i n g t h e f i r s t u n a e r a t e d zone would be d e n i t r i f i e d u s i n g the more complex o r g a n i c s p r e s e n t i n the s e t t l e d sewage a s s u b s t r a t e and a s s u c h , t h e s e c o n d u n a e r a t e d zone would r e c e i v e l i t t l e o r no n i t r a t e l o a d i n g . I n -105-T a b l e 7.1. The Use of P r i m a r y Sludge F e r m e n t a t i o n i n the S i m p l i f i e d N u t r i e n t Removal P r o c e s s ( S e c t i o n 7.1) Parameter S e c t i o n No. 7.1.1 7.1.2 ( C o n t r o l ) (Experiment) Raw I n f l u e n t (mg COD/L) I n f l u e n t T o t a l P (mg/L) I n f l u e n t TKN (mg/L) S e t t . Sewage (mg COD/L) 253 4.02 21.02 332 5.64 33.06 183 Fermenter P r i m a r y Sludge (mg COD/L) Pr i m a r y C l a r i f i e r U nderflow Sludge Age (days) VFA P r o d u c t i o n (mg HAc/L) A c t i v a t e d Sludge P r o c e s s Ortho-P (mg/L): 1 s t Unaerated (mg/L) 2nd Unaerated (mg/L) A e r o b i c (mg/L) E f f l u e n t T o t a l P (mg/L) AP (mg/L) % P Removal 2.50 2.76 2.42 2 .62 1.40 34.8% 1682 10% 10 184 2.58 12.49 1.70 1.72 3 .92 69.5% E f f l u e n t COD (mg/L) 50 ACOD (mg/L) w 203 AP/ACOD 0.0069 NO3-N (mg/L): 1 s t Unaerated (mg/L) 1.27 2nd Unaerated (mg/L) 0.14 A e r o b i c (mg/L) 7.43 E f f l u e n t (mg/L) 7.56 E f f l u e n t TKN (mg/L) P r o c e s s Temp. (°C) 18.5-21.0 Sludge Age (days) 20 A e r o b i c MLSS (mg/L) 2783 SVI 90.8 Sludge Dry Wt. % P 1.46% 53 279 0.0141 0.26 0.21 13.24 12 .70 1.79 19 .0-22.5 20 2619 69.6 3.20% -106-t h i s way a l l of the VFA p r e s e n t i n the a c i d - r i c h f e r m e n t e r l i q u o r would be a v a i l a b l e f o r the e x c e s s b i o l o g i c a l P r e m o v a l mechanism. In C h a p t e r F i v e i t was shown t h a t f a r more e f f i c i e n t use of t h e added sodium a c e t a t e s o l u t i o n was made by a d d i n g i t t o t h e s e c o n d , r a t h e r t han the f i r s t , u n a e r a t e d z o n e . An a d d i t i o n a l m o d i f i c a t i o n made t o the a c t i v a t e d s l u d g e p r o c e s s was t h a t t h e u n a e r a t e d volume f r a c t i o n was i n c r e a s e d from 3 0% t o 4 0%, b u t was s t i l l d i v i d e d i n t o two z o n e s of e q u a l s i z e . The raw d a t a f o r t h i s e x p e r i m e n t a r e shown i n A p p e n d i x A3 and t h e mean r e s u l t s a r e p r e s e n t e d i n T a b l e 7.1. The r e s u l t s p r e s e n t e d i n T a b l e 7.1 c l e a r l y show a s i g n i f i c a n t improvement i n the P r e m o v a l c h a r a c t e r i s t i c s when p r i m a r y s l u d g e f e r m e n t a t i o n was i n c o r p o r a t e d i n t o the d e s i g n of t h e p r o c e s s . The p e r c e n t a g e of i n f l u e n t P removed by t h e p r o c e s s i n c r e a s e d from 34.8% t o 69.5%. The AP/ACOD r a t i o d o u b l e d from 0 .0069 t o 0.0141 w h i l e the d r y w e i g h t p e r c e n t P c o n t e n t of t h e s l u d g e drawn from the a e r o b i c zone i n c r e a s e d from 1.46% t o 3.20%. I t i s q u i t e c l e a r , t h e r e f o r e , t h a t a s i g n i f i c a n t d e g r e e o f e x c e s s b i o l o g i c a l P r e m o v a l was o c c u r r i n g i n the p r o c e s s t h r o u g h o u t the d u r a t i o n o f t h i s e x p e r i m e n t . In a d d i t i o n , a c o n s i d e r a b l e d e g r e e o f P r e l e a s e , up t o a c o n c e n t r a t i o n o f 12.49 mg/L, t o o k p l a c e i n t h e s e c o n d u n a e r a t e d zone. I t a p p e a r s a s i f t h e a d d i t i o n a l s u b s t r a t e p r e s e n t i n the a c i d - r i c h f e r m e n t e r l i q u o r was r e s p o n s i b l e f o r t h i s l a r g e c o n c e n t r a t i o n o f P r e l e a s e d i n t o t h e s u p e r n a t a n t o f the s e c o n d u n a e r a t e d zone and f o r the s i g n i f i c a n t d e g r e e o f e x c e s s b i o l o g i c a l P r e m o v a l e x h i b i t e d by t h e p r o c e s s . -107-With r e g a r d to the N removal e f f i c i e n c y of the p r o c e s s , the i n c o r p o r a t i o n of p r i m a r y sludge f e r m e n t a t i o n i n t o the p r o c e s s d e s i g n does not appear to have had a s i g n i f i c a n t e f f e c t on the p r o c e s s performance. A l t h o u g h the e f f l u e n t n i t r a t e c o n c e n t r a t i o n i n c r e a s e d from 7.56 to 12.70 mg N/L, t h i s can l a r g e l y be a t t r i b u t e d t o the s i g n i f i c a n t l y h i g h e r i n f l u e n t TKN c o n c e n t r a t i o n (33.06 vs 21.02 mg/L) d u r i n g the e x p e r i m e n t a l p e r i o d and the reduced sludge r e c y c l e r a t e . The s l u d g e s e t t l i n g c h a r a c t e r i s t i c s of the p r o c e s s o p e r a t e d w i t h p r i m a r y s l u d g e f e r m e n t a t i o n showed some improvement, w i t h the SVI d e c r e a s i n g from 91 to 7 0. 7.2. The Use of the Fermenter i n the UCT P r o c e s s The o b j e c t i v e of t h i s s e c t i o n was to determine the e x t e n t to which the P removal c h a r a c t e r i s t i c s of the UCT p r o c e s s , a p r o c e s s c o n f i g u r a t i o n d e s i g n e d to s a t i s f y the p r e r e q u i s i t e s f o r e x c e s s b i o l o g i c a l P removal, c o u l d be f u r t h e r enhanced by the use.of p r i m a r y sludge f e r m e n t a t i o n . B r i e f l y , the UCT p r o c e s s , as d e s c r i b e d i n Chapter Two, c o n s i s t s of two u n a e r a t e d zones f o l l o w e d by an a e r o b i c zone. The f i r s t u n a e r a t e d zone, known as the a n a e r o b i c r e a c t o r , r e c e i v e s the i n f l u e n t sewage and the r - r e c y c l e from the second u n a e r a t e d zone, o r a n o x i c r e a c t o r (See Chapter Two, F i g . 2.8). The a n o x i c r e a c t o r r e c e i v e s the r e t u r n sludge r e c y c l e and the i n t e r n a l r e c y c l e from the a e r o b i c zone and i t i s i n t h i s r e a c t o r t h a t a l l of the p r o c e s s d e n i t r i f i c a t i o n t a k e s p l a c e . The b a s i c o b j e c t i v e of the p r o c e s s o p e r a t i o n i s to l i m i t the mass of n i t r a t e e n t e r i n g the a n o x i c r e a c t o r v i a these two r e c y c l e s so t h a t i t a p p r o x i m a t e s the d e n i t r i f i c a t i o n c a p a c i t y of the r e a c t o r . In t h i s way, the n i t r a t e c o n c e n t r a t i o n i n the -108-a n o x i c r e a c t o r i s m a i n t a i n e d a t a n e a r - z e r o v a l u e and o n l y a minimal mass of n i t r a t e i s d i s c h a r g e d to the a n a e r o b i c r e a c t o r v i a the r - r e c y c l e . As such, i t i s i n the a n a e r o b i c r e a c t o r t h a t the p r e r e g u i s i t e c o n d i t i o n s f o r e x c e s s b i o l o g i c a l P removal a r e most l i k e l y t o be met, as l i t t l e o r no d e n i t r i f i c a t i o n t a k e s p l a c e i n the r e a c t o r and a l l of the s i m p l e s u b s t r a t e e n t e r i n g the r e a c t o r i n the incoming sewage i s t h e r e f o r e a v a i l a b l e f o r the exce s s b i o l o g i c a l P removal mechanism. However, i n the case of UCT p r o c e s s e s t r e a t i n g t y p i c a l l y low o r g a n i c s t r e n g t h N o r t h American wastewaters, i t i s thought t h a t t h e r e are i n s u f f i c i e n t q u a n t i t i e s of the r e q u i r e d s u b s t r a t e s p r e s e n t i n the wastewater, and t h a t the c o n c e n t r a t i o n of these s u b s t r a t e s can be i n c r e a s e d by u s i n g p r i m a r y sludge f e r m e n t a t i o n . D u r i n g the c o n t r o l p e r i o d , the UCT p r o c e s s r e c e i v e d raw sewage o n l y , and d u r i n g the e x p e r i m e n t a l p e r i o d the i n f l u e n t was p r e t r e a t e d u s i n g p r i m a r y sludge f e r m e n t a t i o n i n o r d e r to i n c r e a s e the VFA c o n c e n t r a t i o n e n t e r i n g the p r o c e s s . Both the s e t t l e d sewage and the fe r m e n t e r l i q u o r were d i s c h a r g e d i n t o the a n a e r o b i c r e a c t o r of the p r o c e s s . Schematic diagrams of the two p r o c e s s c o n f i g u r a t i o n s used a r e p r e s e n t e d i n F i g u r e 7.2. 7.2.1. C o n t r o l The UCT p r o c e s s c o n f i g u r a t i o n used i n t h i s e x p e r i m e n t had b o t h the a n a e r o b i c and the a n o x i c r e a c t o r s each c o m p r i s i n g 20% of the p r o c e s s volume w i t h the r e m a i n i n g 6 0% of the p r o c e s s volume b e i n g m a i n t a i n e d under a e r o b i c c o n d i t i o n s . The s l u d g e r e t u r n and the r - r e c y c l e were m a i n t a i n e d a t a r a t i o of 1:1 w i t h r e s p e c t to the i n f l u e n t f l o w r a t e and the i n t e r n a l r e c y c l e was g e n e r a l l y kept a t - 1 0 9 -CONTROL A N A E R O B I C ANOXIC A E R O B I C Z O N E ZONE Z O N E 3 = 1 I N F L U E N T S E C O N D A R Y C L A R I F I E R E F F L U E N T 6 6 6 6 R E T U R N S L U D G E I > I EXPERIMENT P R I M A R Y C L A R I F I E R A N A E R O B I C ANOXIC Z O N E Z O N E I I N F L U E N T A E R O B I C Z O N E S E C O N D A R Y C L A R I F I E R E F F L U E N T R E T U R N S L U D G E 1.5 « T W O STAGE P R I M A R Y S L U D G E F E R M E N T E R EQUIPPED WITH S E C O N D A R Y C L A R I F I E R F i g u r e 7.2. The use of p r i m a r y s l u d g e f e r m e n t a t i o n i n the UCT p r o c e s s - C o n t r o l a n d E x p e r i m e n t a l p r o c e s s c o n f i g u r a t i o n s -110-a 3:1 r e c y c l e r a t i o , a l t h o u g h t h i s was p e r i o d i c a l l y reduced i n o r d e r to minimize the n i t r a t e c o n c e n t r a t i o n i n the a n o x i c r e a c t o r . The raw data from t h i s experiment are shown i n Appendix A3 and the mean v a l u e s are p r e s e n t e d i n Table 7.2. The r e s u l t s of t h i s experiment i n d i c a t e t h a t t h e r e was some degree of e x c e s s b i o l o g i c a l P removal o c c u r r i n g i n the UCT p r o c e s s , even w i t h o u t the use of p r i m a r y sludge f e r m e n t a t i o n . The P removal e f f i c i e n c y , as measured by the AP/ACOD r a t i o , was 0.0086. T h i s f i g u r e i s about 2 5% g r e a t e r than t h a t f o r the s i m p l i f i e d u n a e r a t e d / a e r a t e d n u t r i e n t removal p r o c e s s used i n the c o n t r o l p e r i o d of S e c t i o n 7.1. The mean dry weight p e r c e n t P c o n t e n t of the sludge was 2.11%, an i n c r e a s e of about 4 4% o v e r t h a t a c h i e v e d i n S e c t i o n 7.1.1, i n d i c a t i n g t h a t some degree of e x c e s s p o l y - P s t o r a g e took p l a c e d u r i n g the experiment. Furthermore, the r e a c t o r o r t h o - P c o n c e n t r a t i o n s p r e s e n t e d i n Table 7.2 show t h a t a s m a l l degree of P r e l e a s e o c c u r r e d i n the a n a e r o b i c r e a c t o r . 7.2.2. Experiment In t h i s e x p e r i m e n t , the s e t t l e d sewage from the p r i m a r y c l a r i f i e r was d i s c h a r g e d i n t o the a n a e r o b i c zone of the p r o c e s s , as i n the case of the e x p e r i m e n t a l p e r i o d of S e c t i o n 7.1. The p r i m a r y sludge was pumped i n t o the 2-stage p r i m a r y s l u d g e f e r m e n t e r which was o p e r a t e d a t a sludge age of 10 days, and the f e r m e n t e r l i q u o r from the c l a r i f i e r was d i s c h a r g e d t o g e t h e r w i t h the s e t t l e d sewage i n t o the a n a e r o b i c r e a c t o r a t the head end of the p r o c e s s . Two a d d i t i o n a l changes were made to the o p e r a t i o n of the UCT - I l l -Table 7.2. The Use of Primary Sludge Fermentation in the UCT Process (Section 7.2) Sect ion No. Parameter 7.2.1 7.2.2 (Control) (Expe riment) Raw Influent (mg COD/L) 236 330 Influent Total P (mg/L) 3.54 5 .43 Influent TKN (mg/L) 20.20 32.40 Sett. Sewage (mg COD/L) — 186 Fermenter Primary Sludge - 16 82 Primary C l a r i f i e r Underflow - 10% Sludge Age (days) - 10 VFA Production (mg HAc/L) — 148 Activated Sludge Process Ortho-P (mg/L): Anaerobic Zone (mg/L) 3 .88 10.78 Anoxic Zone (mg/L) 2.21 5.27 Aerobic Zone (mg/L) 1.82 1.59 Effluent Total P (mg/L) 1.72 1.47 AP (mg/L) 1.72 3.96 % P Removal (mg/L) 5 0.0% 72.9% Effluent COD (mg/L) 24 39 ACOD (mg/L) 212 291 AP/ACOD 0.0086 0.0136 NO3-N (mg/L) Anaerobic Zone (mg/L) 0.08 0.35 Anoxic Zone (mg/L) 0.94 2.74 Aerobic Zone (mg/L) 3 .95 12.19 Effluent (mg/L) 3 .07 11.88 Effluent TKN (mg/L) — 1.50 Process Temp. (°C) Sludge Age (days) 20 20 Aerobic MLSS (mg/L) 3777 3791 SVI 207.3 109.1 Sludge Dry Wt. % P 2.11% 3.10% -112-p r o c e s s . The i n t e r n a l mixed l i q u o r r e c y c l e was e l i m i n a t e d and the r e t u r n s l u d g e r e c y c l e r a t i o was i n c r e a s e d to 1.5:1 w i t h r e s p e c t to the i n f l u e n t f l o w r a t e . I n t h i s e xperiment, t h e r e f o r e , the p r o c e s s was not o p t i m i z e d f o r n i t r o g e n r e m o v a l . The raw data f o r t h i s experiment are shown i n Appendix A3 and the mean v a l u e s are p r e s e n t e d i n Table 7.2. As i n the case of the p r e v i o u s s e c t i o n , the P removal c h a r a c t e r i s t i c s of the UCT p r o c e s s were s i g n i f i c a n t l y enhanced, a l t h o u g h not t o the same e x t e n t , by the i n c o r p o r a t i o n of p r i m a r y sludge f e r m e n t a t i o n i n t o the p r o c e s s d e s i g n . The P removal e f f i c i e n c y of the p r o c e s s i n c r e a s e d from 0 .0086 to 0.0136 mg P/mg COD between the e x p e r i m e n t a l and c o n t r o l p e r i o d s , an i n c r e a s e of 58%. The mean dry weight p e r c e n t P c o n t e n t of the sludge i n c r e a s e d from 2.11% to 3.10%, i n d i c a t i n g t h a t a s i g n i f i c a n t degree of exc e s s b i o l o g i c a l P removal o c c u r r e d d u r i n g t h i s e x p e r i m e n t . A r e l a t i v e l y l a r g e c o n c e n t r a t i o n of P was r e l e a s e d i n t o the s u p e r n a t a n t of the a n a e r o b i c r e a c t o r , p r o b a b l y as a r e s u l t of the i n c r e a s e d mass of VFA's e n t e r i n g the r e a c t o r v i a the a c i d - r i c h f e r m e n t e r l i q u o r . I t i s i n t e r e s t i n g t o n o t e , however, t h a t when comparing the performance of the UCT and the s i m p l i f i e d n u t r i e n t removal p r o c e s s , w i t h b o t h p r o c e s s e s having p r i m a r y sludge f e r m e n t a t i o n i n c o r p o r a t e d i n t o the d e s i g n ( i . e . S e c t i o n s 7.1.2 and 7.2.2), the P removal c h a r a c t e r i s t i c s of the s i m p l i f i e d p r o c e s s were s l i g h t l y b e t t e r . Both the P removal e f f i c i e n c y and the dry weight p e r c e n t P c o n t e n t of the sludge were a l i t t l e h i g h e r , v i z . 0.0141 vs 0.0136 mg P/mg COD and 3.20% vs 3.10%, r e s p e c t i v e l y . T h i s can, i n a l l l i k e l i h o o d , be -113-a t t r i b u t e d to the f a c t t h a t the VFA p r o d u c t i o n of the fermenter was s i g n i f i c a n t l y l ower d u r i n g the experiment d e s c r i b e d i n S e c t i o n 7.2.2, than i t was i n the e a r l i e r e x periment v i z . 148 vs 184 mg HAc/L. The h i g h e r e f f l u e n t n i t r a t e c o n c e n t r a t i o n observed i n the e x p e r i m e n t a l p e r i o d o v e r t h a t i n the c o n t r o l p e r i o d can p a r t i a l l y be a t t r i b u t e d t o the f a c t t h a t the p r o c e s s c o n f i g u r a t i o n was no l o n g e r o p t i m i z e d f o r n i t r o g e n removal. I n a d d i t i o n , the i n f l u e n t TKN c o n c e n t r a t i o n was s i g n i f i c a n t l y h i g h e r i n t h i s experiment than i n the c o n t r o l p e r i o d (32.4 vs 20.2 mg/L) which r e s u l t e d i n a much h i g h e r mass of n i t r a t e b e i n g n i t r i f i e d and c o n s e q u e n t l y , a h i g h e r e f f l u e n t n i t r a t e c o n c e n t r a t i o n . I n c o r p o r a t i o n of p r i m a r y sludge f e r m e n t a t i o n i n t o the d e s i g n of the UCT p r o c e s s c o n f i g u r a t i o n a l s o appears to have improved the s e t t l i n g c h a r a c t e r i s t i c s of the s l u d g e , w i t h the mean SVI v a l u e d e c r e a s i n g from 207 t o 110 between the c o n t r o l and e x p e r i m e n t a l pe r i o d s . -114-CHAPTER EIGHT DISCUSSION OF RESULTS 8.1. I n t r o d u c t i o n In r e c e n t y e a r s e x c e s s b i o l o g i c a l P r e m o v a l i n t h e a c t i v a t e d s l u d g e p r o c e s s has r e c e i v e d an i n c r e a s i n g amount of a t t e n t i o n from many r e s e a r c h w o r k e r s w o r l d w i d e , p r i m a r i l y due to i t s r e c o g n i t i o n a s a v i a b l e method of r e m o v i n g l a r g e masses of P from w a s t e w a t e r p o i n t s o u r c e s . S i n c e t h e o n s e t of t h e r e s e a r c h r e p o r t e d i n t h i s t h e s i s , a number of i n t e r n a t i o n a l c o n f e r e n c e s and s e m i n a r s d e a l i n g w i t h b i o l o g i c a l P r e m o v a l have been h e l d . I n a d d i t i o n , an i n t e r n a t i o n a l s t u d y g r o u p on "P Removal i n B i o l o g i c a l Sewage T r e a t m e n t P r o c e s s e s " , w i t h a membership of o v e r 100 r e s e a r c h w o r k e r s , has been formed u n d e r t h e a u s p i c e s of t h e I n t e r n a t i o n a l A s s o c i a t i o n of Water P o l l u t i o n R e s e a r c h and C o n t r o l (IAWPRC). As a r e s u l t , c o n s i d e r a b l e p r o g r e s s has been made i n many a s p e c t s o f b i o l o g i c a l P r e m o v a l w h i l e t h e r e s e a r c h r e p o r t e d h e r e i n was i n p r o g r e s s . F o r t h i s r e a s o n , i t was d e c i d e d t o d i s c u s s the f i n d i n g s of t h i s r e s e a r c h by d e a l i n g w i t h e a c h a s p e c t and i t s c o n t r i b u t i o n t o t h e f u r t h e r d e v e l o p m e n t of e x c e s s b i o l o g i c a l P r e m o v a l t e c h n o l o g y i n the a c t i v a t e d s l u d g e p r o c e s s , w i t h i n the c o n t e x t of some of t h e r e c e n t p a r a l l e l r e s e a r c h t h a t has been c a r r i e d o u t by o t h e r s d u r i n g t h e c o u r s e of t h i s s t u d y . 8.2. The E x c e s s B i o l o g i c a l P Removal Mechanism The d e f i n i t i o n of the p r e r e q u i s i t e s of t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism i n terms of t h e c o n c e n t r a t i o n o f t h e " r e a d i l y b i o d e g r a d a b l e COD" s u r r o u n d i n g t h e o r g a n i s m s i n t h e a n a e r o b i c -115-zone of the p r o c e s s , as s e t out by S i e b r i t z e t a l . ( 1982 , 1983) was a m i l e s t o n e i n the u n d e r s t a n d i n g of the n a t u r e of the P removal mechanism. T h i s i s p r i m a r i l y because i t r e p r e s e n t e d a major s h i f t i n emphasis away from d e f i n i n g the p r e r e q u i s i t e s of the removal mechanism i n terms of a c e r t a i n minimum degree of a n a e r o b i c s t r e s s i n the a n a e r o b i c zone, i n f a v o u r of r e c o g n i z i n g the importance of the a v a i l a b i l i t y of carbonaceous s u b s t r a t e to the organisms i n the zone. However, the " r e a d i l y b i o d e g r a d a b l e " h y p o t h e s i s s u f f e r s from a number of t h e o r e t i c a l and p r a c t i c a l l i m i t a t i o n s . F i r s t l y , the d e t e r m i n a t i o n of the r e a d i l y b i o d e g r a d a b l e COD c o n c e n t r a t i o n p r e s e n t i n a wastewater i s not based on any s p e c i f i c c h e m i c a l a n a l y s i s of the wastewater. I n s t e a d , i t r e q u i r e s the o p e r a t i o n of a s h o r t sludge age, c o m p l e t e l y a e r o b i c , c y c l i c a l l y fed a c t i v a t e d s l u d g e p r o c e s s t r e a t i n g the s p e c i f i c waste, and measuring the drop i n oxygen consumption r a t e a t the t e r m i n a t i o n of the feed c y c l e . Recent e x p e r i e n c e i n the o p e r a t i o n of these u n i t s a t the N.I.W.R. l a b o r a t o r i e s i n P r e t o r i a , South A f r i c a and a t the U n i v e r s i t y of B r i t i s h Columbia (Manoharan, 19 85) has r e v e a l e d a number of p r a c t i c a l problems a f f e c t i n g the u s e f u l n e s s of t h i s t e c h n i q u e . The two most i m p o r t a n t of these problems a r e f i l a m e n t o u s sludge b u l k i n g , and d i f f i c u l t i e s a s s o c i a t e d w i t h the s u p p r e s s i o n of n i t r i f i c a t i o n , which i n t r o d u c e s a c o n f o u n d i n g oxygen demand on the system. Furthermore, the l a c k of a p r e c i s e c h e m i c a l d e f i n i t i o n of " r e a d i l y b i o d e g r a d a b l e COD" does not r e c o g n i z e the p o s s i b i l i t y of some r e a d i l y b i o d e g r a d a b l e wastewater components b e i n g more e f f e c t i v e than o t h e r s i n i n d u c i n g the e x c e s s -116-b i o l o g i c a l P r e m o v a l mechanism. S u b s t r a t e t h a t i s r e a d i l y u t i l i z a b l e by a e r o b i c h e t e r o t r o p h s i n g e n e r a l i s n o t n e c e s s a r i l y r e a d i l y u t i l i z a b l e i n the e x c e s s b i o l o g i c a l P r e m o v a l mechanism. F i n a l l y , the h y p o t h e s i s m e r e l y s t a t e s t h a t a c e r t a i n minimum c o n c e n t r a t i o n of r e a d i l y b i o d e g r a d a b l e COD be a v a i l a b l e to t h e o r g a n i s m s i n the a n a e r o b i c zone b u t d o e s n o t c l a r i f y t h e r o l e of t h e s u b s t r a t e i n the P r e m o v a l mechanism. The r e s e a r c h p r e s e n t e d h e r e i n c l e a r l y d e m o n s t r a t e s t h a t a number of s u b s t r a t e s w h i c h c o u l d be c l a s s i f i e d a s b e i n g " r e a d i l y b i o d e g r a d a b l e COD" have w i d e l y d i f f e r i n g e f f e c t s on t h e P r e l e a s e mechanism u n d e r a n a e r o b i c c o n d i t i o n s . F o r example, sodium a c e t a t e and p r o p i o n i c a c i d p r o v e d to be t h e most e f f e c t i v e i n i n d u c i n g a n a e r o b i c P r e l e a s e w h i l e g l u c o s e and b u t y r i c a c i d were o n l y h a l f a s e f f e c t i v e on t h e b a s i s o f t h e i r COD v a l u e . T h i s seems t o s u g g e s t t h a t the e f f e c t i v e n e s s of a s p e c i f i c s u b s t r a t e i s some i n v e r s e f u n c t i o n o f t h e c o m p l e x i t y of t h e s u b s t r a t e m o l e c u l e . F u r t h e r m o r e , t h e f a c t t h a t a c e t i c a c i d was s i g n i f i c a n t l y l e s s e f f e c t i v e t h a n s o d i u m a c e t a t e i n i n d u c i n g a n a e r o b i c P r e l e a s e on an e q u i v a l e n t COD b a s i s s u g g e s t s t h a t t h e i o n i c form of the s u b s t r a t e i s a l s o i m p o r t a n t t o i t s r o l e i n t h e P r e m o v a l mechanism. A n a e r o b i c b a t c h t e s t i n g , u s i n g v a r i o u s c o n c e n t r a t i o n s of s o d i u m a c e t a t e a t the s t a r t of t h e t e s t and m e a s u r i n g t h e o r t h o - P and a c e t a t e s u p e r n a t a n t p r o f i l e s , r e v e a l e d much a b o u t t h e f a t e of t h e s u b s t r a t e d u r i n g a n a e r o b i c P r e l e a s e . F o r a l l i n i t i a l s u b s t r a t e c o n c e n t r a t i o n s , P r e l e a s e and s u b s t r a t e u t i l i z a t i o n a p p e a r t o be -117-i n t e g r a l p a r t s of an exchange phenomenon, w i t h the c e s s a t i o n of P r e l e a s e and s u b s t r a t e u t i l i z a t i o n b e i n g c o i n c i d e n t . The end of the P r e l e a s e phase o c c u r r e d e i t h e r due to t h e o n s e t of s u b s t r a t e l i m i t i n g c o n d i t i o n s o r due to the e x h a u s t i o n of i n t r a c e l l u l a r r e s e r v e s of s t o r e d P. In the l a t t e r c a s e , no more s u b s t r a t e was removed from the s u p e r n a t a n t , i n d i c a t i n g t h a t P r e l e a s e p l a y s an i n t e g r a l r o l e i n the t r a n s p o r t of carbonaceous s u b s t r a t e i n t o the c e l l . D u r i n g the P r e l e a s e phase, 0.91 mg of P were r e l e a s e d f o r e v e r y mg of sodium a c e t a t e (measured as HAc) u t i l i z e d . T h i s r e p r e s e n t s a molar r a t i o of 1.76 moles P/mole HAc. I n a s e r i e s of b a t c h e x periments s i m i l a r i n concept to those r e p o r t e d h e r e , Fukase e t a l . ( 1982) o b t a i n e d a p h o s p h a t e : a c e t a t e molar r a t i o of 0.9:1 w h i l e A r v i n ( 1985) and Comeau e t a l . ( 1985) r e p o r t e d m o lar exchange r a t i o s of 1.4:1. S i e b r i t z e t a l . (1983) r e p o r t e d a p h o s p h a t e : a c e t a t e molar r a t i o of 2:1 but t h i s v a l u e was based on s u b s t r a t e a v a i l a b i l i t y r a t h e r than u t i l i z a t i o n . I n b a t c h t e s t s where an a e r o b i c phase f o l l o w e d the a n a e r o b i c P r e l e a s e p e r i o d , P uptake was observed to o c c u r a t a r a p i d i n i t i a l r a t e which slowed down somewhat a f t e r a p e r i o d of about one hour. There appeared to be some l o o s e c o r r e l a t i o n between the mass of P r e l e a s e d a n a e r o b i c a l l y and the mass of P t a k e n up under subsequent a e r o b i c c o n d i t i o n s . However, these r e s u l t s were not as c o n c l u s i v e as those of W e n t z e l l e t a l . ( 19 84) who were a b l e to d e v elop the f o l l o w i n g r e l a t i o n s h i p between P r e l e a s e u p t a k e : P uptake (mg/L) = 5.5 + 1.13XP r e l e a s e (mg/L) The above e q u a t i o n s u g gests t h a t the g r e a t e r the degree of a n a e r o b i c P r e l e a s e , the g r e a t e r i s the system P removal of the -118-process. This supports an early observation of Barnard (1976), who, in addition to being the f i r s t to e x p l i c i t l y state that there was a connection between P release and excess b i o l o g i c a l P removal, also observed that the degree of P release determined the degree of system P removal. In general, the findings of t h i s research support the proposed biochemical models for the excess b i o l o g i c a l P removal mechanism of a number of research workers who endeavoured to explain why the anaerobic/aerobic sequence i s essential for the p r o l i f e r a t i o n of organisms capable of storing excess quantities of phosphorus in the activated sludge process. For example, s i g n i f i c a n t amounts of carbon storage i n the form of poly-B-hydroxybutyrate (PHB) have been reported to occur in the anaerobic zone of processes exhibiting excess b i o l o g i c a l P removal (Nicholls and Osborn ( 1979), Fukase et a l . ( 1982) and Comeau ( 1984)). I t seems l i k e l y that the a b i l i t y to store carbon as PHB i n a stressed environment, where aerobic metabolism i s impossible (in the absence of both dissolved oxygen and n i t r a t e ) , i s the key to the p r o l i f e r a t i o n of these organisms i n the process. Upon entering the aerobic zone of the process, where substrate l i m i t i n g conditions often occur, organisms that have i n t r a c e l l u l a r l y stored carbon have a decided advantage over organisms that must rely on membrane transport in the highly competitive activated sludge environment. It i s in the aerobic environment that these organisms store vast guantities of phosphorus not needed for basic metabolic purposes, in long chains of inorganic polyphosphate known as volutin granules. Fukase et al . ( 1982) - U n -r e p o r t e d a d r y w e i g h t p e r c e n t P c o n t e n t o f a r o u n d 12% i n s l u d g e drawn from the a e r o b i c zone of a l a b o r a t o r y - s c a l e a n a e r o b i c / a e r o b i c a c t i v a t e d s l u d g e p r o c e s s t r e a t i n g a s y n t h e t i c f e e d l a r g e l y made up o f sodium a c e t a t e . I t i s t h e s e p o l y p h o s p h a t e r e s e r v e s t h a t a r e b r o k e n down and h y d r o l y z e d when the o r g a n i s m s r e - e n t e r the a n a e r o b i c zone o f t h e p r o c e s s , p r e s u m a b l y i n o r d e r to f a c i l i t a t e t h e t r a n s p o r t and i n t r a c e l l u l a r s t o r a g e of t h e a v a i l a b l e c a r b o n a c e o u s s u b s t r a t e i n t h e z o n e . Comeau e t a l . ( 1985b) r e f e r s t o B i o - P b a c t e r i a ( b a c t e r i a r e s p o n s i b l e f o r enhanced b i o l o g i c a l P r e m o v a l ) a s c a p a b l e o f s t o r i n g b o t h p o l y p h o s p h a t e u n d e r a e r o b i c c o n d i t i o n s and c a r b o n u n d e r a n a e r o b i c c o n d i t i o n s . In t h e i r c o m p r e h e n s i v e b i o c h e m i c a l model o f t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism f o r b o t h a n a e r o b i c and a e r o b i c c o n d i t i o n s ( s e e F i g . 8 .1), the y s u g g e s t t h a t a n a e r o b i c P r e l e a s e p l a y s a p a s s i v e r o l e i n the P r e m o v a l mechanism. Because a c e t a t e must be t r a n s p o r t e d i n t o t h e c e l l i n an e l e c t r o c h e m i c a l l y n e u t r a l form ( i . e . a s H A c ) , t h e p r i m a r y f u n c t i o n s e r v e d by t h e d e g r a d a t i o n of p o l y p h o s p h a t e i s t o r e - e s t a b l i s h the pH g r a d i e n t a c r o s s t h e c e l l membrane, t h e r e b y f a c i l i t a t i n g more a c e t a t e u p t a k e . They s u g g e s t t h a t P r e l e a s e t a k e s p l a c e a s a r e s u l t of th e i n t r a c e l l u l a r a c c u m u l a t i o n of t h i s u n u s a b l e m e t a b o l i t e . F u r t h e r m o r e , t h e y t h e o r i z e t h a t p o l y - P a l s o s e r v e s a s t h e e n e r g y s o u r c e i n the s y n t h e s i s o f a c e t y l CoA from s u b s t r a t e s s u c h a s a c e t a t e p r i o r t o t h e i r s t o r a g e a s PHB. They a l s o p o i n t o u t t h a t K +, M g + + and C a + + a r e c o - t r a n s p o r t e d a c r o s s t h e c e l l w a l l t o g e t h e r w i t h the p h o s p h a t e i n r a t i o s t h a t r e m a i n the same f o r b o t h uptake and r e l e a s e c o n d i t i o n s . I t a p p e a r s , t h e r e f o r e , t h a t -120-F i g . 8.1a. S i m p l i f i e d model f o r a n a e r o b i c metabolism of Bio-P b a c t e r i a . T r a n s p o r t and s t o r a g e of s i m p l e carbon s u b s t r a t e s such as a c e t a t e r e q u i r e energy o b t a i n e d from the breakdown of polyphosphate r e s e r v e s . Phosphate, an unusable m o l e c u l e by the c e l l under such c o n d i t i o n s , i s r e l e a s e d i n t o s o l u t i o n . Adapted from Comeau e t a l . (1985b). F i g . 8.1b. S i m p l i f i e d model f o r a e r o b i c metabolism of Bio-P b a c t e r i a . Carbon from i n t e r n a l r e s e r v e s o r from s o l u t i o n i s used w i t h oxygen ( o r n i t r a t e ) to produce energy f o r tne growth of Bio-P b a c t e r i a . Energy i s used f o r phosphate t r a n s p o r t and i t s s t o r a g e as p o l y p h o s p h a t e . Adapted from Comeau e t a l . ( 1985b). -121-p o l y p h o s p h a t e s t o r a g e , and t h e r e f o r e e x c e s s b i o l o g i c a l P r e m o v a l i n g e n e r a l , p l a y s a r o l e t h a t i s s e c o n d a r y to c a r b o n s t o r a g e i n t h e p r o l i f e r a t i o n o f B i o - P b a c t e r i a i n the a c t i v a t e d s l u d g e p r o c e s s . T h i s , of c o u r s e , l e a d s to t h e q u e s t i o n of why c e l l s s t o r e p o l y p h o s p h a t e a t a l l when s u b j e c t e d to s t r e s s f u l c o n d i t i o n s . The r o l e o f p o l y p h o s p h a t e a s a r e s e r v e m a t e r i a l f o r g r o w t h i s w e l l r e c o g n i z e d b u t i t s r o l e a s a n e n e r g y s o u r c e i s s t i l l u n d e r i n v e s t i g a t i o n . H a r o l d ( 1966) p o i n t s o u t t h a t p o l y p h o s p h a t e a p p e a r s t o be s y n t h e s i z e d by t h e t r a n s f e r of p h o s p h a t e m o l e c u l e s from a d e n o s i n e t r i p h o s p h a t e (ATP) t o g r o w i n g c h a i n s of p o l y p h o s p h a t e and s u g g e s t s t h a t , from an e v o l u t i o n a r y v i e w p o i n t , p o l y p h o s p h a t e may p r e d a t e ATP a s t h e c h i e f e n e r g y c a r r i e r i n b a c t e r i a l c e l l s . T h e r e f o r e , a b i l i t y o f c e r t a i n b a c t e r i a t o s t o r e p o l y p h o s p h a t e may be t h e r e s u l t of a " g e n e t i c throwback" from t h e e v o l u t i o n o f e a r l y b a c t e r i a l c e l l s . 8.3. E f f e c t of N i t r a t e on E x c e s s B i o l o g i c a l P h o s p h o r u s Removal N i t r a t e i s the most a b u n d a n t form o f combined oxygen p r e s e n t i n n u t r i e n t r e m o v a l a c t i v a t e d s l u d g e p r o c e s s e s , l a r g e l y b e c a u s e o f t h e i n c o r p o r a t i o n o f b o t h n i t r i f i c a t i o n and d e n i t r i f i c a t i o n i n t o t h e d e s i g n of t h e s e p r o c e s s e s . The d e t r i m e n t a l e f f e c t o f n i t r a t e e n t e r i n g t h e a n a e r o b i c zone of p r o c e s s e s d e s i g n e d f o r e x c e s s b i o l o g i c a l P r e m o v a l was f i r s t p o i n t e d o u t by B a r n a r d ( 1976). He s t a t e d t h a t n i t r a t e w o u l d i n c r e a s e t h e r e d o x p o t e n t i a l o f t h e zone, t h e r e b y r e d u c i n g t h e d e g r e e o f a n a e r o b i c s t r e s s t o a l e v e l t h a t may n o t i n d u c e a n a e r o b i c P r e l e a s e , w h i c h a t the time he c o n s i d e r e d t o be t h e p r e r e q u i s i t e f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism t o o p e r a t e . B a r n a r d ' s o b s e r v a t i o n r e g a r d i n g -122-t h e d e t r i m e n t a l e f f e c t o f n i t r a t e e n t e r i n g t h e zone was c o n f i r m e d by McLaren and Wood ( 1976), N i c h o l l s ( 1977), S i m p k i n s and M c L a r e n ( 1978) and o t h e r s , and was t h e p r i m a r y m o t i v a t i o n f o r the d e v e l o p m e n t of t h e UCT p r o c e s s by R a b i n o w i t z and M a r a i s ( 1980) and S i e b r i t z e t a l . ( 1 9 8 0 ) . The UCT p r o c e s s c o n f i g u r a t i o n i s one i n which a z e r o n i t r a t e d i s c h a r g e t o t h e a n a e r o b i c r e a c t o r c a n be g u a r a n t e e d u n d e r most o p e r a t i n g c o n d i t i o n s . However, i t was i n t h e q u a n t i f i c a t i o n o f t h e n e g a t i v e e f f e c t o f n i t r a t e e n t e r i n g t h e a n a e r o b i c zone o f t h e p r o c e s s t h a t t h e r e e x i s t e d much u n c e r t a i n t y . In t h e d e v e l o p m e n t o f t h e " r e a d i l y b i o d e g r a d a b l e COD" h y p o t h e s i s t o d e f i n e t h e p r e r e q u i s i t e s f o r e x c e s s b i o l o g i c a l P r e m o v a l , S i e b r i t z e t a l . ( 1982 , 19 83 ) assumed t h a t any n i t r a t e e n t e r i n g t h e a n a e r o b i c zone w o u l d r e s u l t i n t h e o x i d a t i o n of r e a d i l y b i o d e g r a d a b l e COD i n t h e zone i n a r a t i o d e t e r m i n e d by t h e k i n e t i c t h e o r y o f d e n i t r i f i c a t i o n o f van H a a n d e l e t a l . ( 1 9 8 1 ) . The d e n i t r i f i c a t i o n t h e o r y s t a t e s t h a t i n the o x i d a t i o n o f s u b s t r a t e u s i n g n i t r a t e a s t h e t e r m i n a l e l e c t r o n a c c e p t o r , 8.6 mg o f s u b s t r a t e (as COD) a r e o x i d i z e d f o r e v e r y mg of n i t r a t e ( a s N) d e n i t r i f i e d . S i e b r i t z e t a l . ( 1982) h y p o t h e s i z e d t h a t i n t h e c a s e o f the e n h a n c e d b i o l o g i c a l P r e m o v a l p r o c e s s , the r e a d i l y b i o d e g r a d a b l e COD r e g u i r e d f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism i s u t i l i z e d p r e f e r e n t i a l l y i n the d e n i t r i f i c a t i o n r e a c t i o n a t a r a t e o f 8.6 mg COD/mg NO^-N e n t e r i n g t h e a n a e r o b i c zone o f t h e p r o c e s s . The a n a e r o b i c b a t c h t e s t s p r e s e n t e d i n t h i s t h e s i s ( S e c t i o n 4.3, C h a p t e r 4) c l e a r l y show t h a t , a l t h o u g h th e p r e s e n c e of n i t r a t e i s i n h i b i t o r y t o t h e a n a e r o b i c P r e l e a s e mechanism, the i n h i b i t o r y -123-e f f e c t i s not as g r e a t as t h a t suggested by S i e b r i t z e t a l . ( 1982). Furthermore, the i n h i b i t o r y e f f e c t , w h i l e i n c r e a s i n g w i t h i n c r e a s i n g n i t r a t e c o n c e n t r a t i o n s , i s an i n v e r s e f u n c t i o n of the mass of s u b s t r a t e a v a i l a b l e to t h e organisms. For example, i n the f l a s k s t h a t r e c e i v e d . a n i n i t i a l s u b s t r a t e c o n c e n t r a t i o n of 100 mg COD/L of a c e t a t e , i n i t i a l n i t r a t e c o n c e n t r a t i o n s of up to 9 mg N/L had no e f f e c t on the P r e l e a s e mechanism and i n the f l a s k t h a t had an i n i t i a l n i t r a t e c o n c e n t r a t i o n of 12 mg N/L, the P r e l e a s e mechanism was o n l y s l i g h t l y i n h i b i t e d . However, i n the f l a s k s t h a t r e c e i v e d an i n i t i a l s u b s t r a t e c o n c e n t r a t i o n of 50 mg COD/L, the presence of n i t r a t e i n c o n c e n t r a t i o n s as low as 3 mg N/L proved to be i n h i b i t o r y to the P r e l e a s e mechanism. I n the former ca s e , the i n i t i a l presence of 12 mg N/L of n i t r a t e ( a l l of which was d e n i t r i f i e d i n the f i r s t hour of the experiment) r e q u i r e d 12 X 8.6 = 103.2 mg/L of COD f o r d e n i t r i f i c a t i o n , i . e . a l l of the i n i t i a l s u b s t r a t e c o n c e n t r a t i o n , a c c o r d i n g t o the d e n i t r i f i c a t i o n t h e o r y of van Haandel e t a l . (1981). I n the l a t t e r c a s e , the i n h i b i t o r y e f f e c t of the n i t r a t e on the P r e l e a s e mechanism was o n l y a maximum of 3 .0 mg P r e l e a s e p e r mg of n i t r a t e (as N) p r e s e n t i n the r e a c t o r a t the s t a r t of the e x p e r i m e n t . Combining t h i s v a l u e w i t h the AP/AHAc v a l u e of 0.89 mg P/mg HAc ( e g u i v a l e n t to 0.83 mg P/mg COD) found i n the c o n t r o l f l a s k t h a t r e c e i v e d no i n i t i a l n i t r a t e c o n c e n t r a t i o n , the i n h i b i t o r y e f f e c t of the n i t r a t e i s e q u a l t o : 3 .0/0.83 = 3 .60 mg COD/mg NO3-N which i s l e s s than one h a l f of t h a t p r e d i c t e d by the d e n i t r i f i c a t i o n t h e o r y , assuming p r e f e r e n t i a l usage of the -124-s u b s t r a t e i n the d e n i t r i f i t i o n r e a c t i o n . The r e s u l t s o f t h e s e e x p e r i m e n t s c l e a r l y show t h a t t h e i n h i b i t o r y e f f e c t of n i t r a t e on the P r e l e a s e mechanism i s n o t a s g r e a t a s t h a t s u g g e s t e d by c u r r e n t t h e o r y . T h e r e a r e two p o s s i b l e e x p l a n a t i o n s f o r t h i s : e i t h e r the s u b s t r a t e r e q u i r e m e n t s f o r d e n i t r i f i c a t i o n (8.6 mg COD/mg N) i s o v e r e s t i m a t e d i n the d e n i t r i f i c a t i o n t h e o r y o f van Ha a n d e l e t a l . ( 1 9 8 1 ) , o r t h e s u b s t r a t e i s n o t u t i l i z e d p r e f e r e n t i a l l y i n t h e d e n i t r i f i c a t i o n r e a c t i o n (and t h u s r e n d e r e d u n a v a i l a b l e f o r t h e P r e l e a s e mechanism), a s h y p o t h e s i z e d by S i e b r i t z e t a l . ( 1 9 8 2 ) , i . e . t h a t t h e r e e x i s t s some phenomenon whereby t h e same s u b s t r a t e c a n be u t i l i z e d i n b o t h the P r e l e a s e mechanism and t h e d e n i t r i f i c a t i o n r e a c t i o n . T h e s e two p o s s i b l e e x p l a n a t i o n s r e q u i r e f u r t h e r e x a m i n a t i o n . The s u b s t r a t e r e q u i r e m e n t s f o r de n i t r i f i c a t i o n due to t h e o x i d a t i o n o f . r e a d i l y b i o d e g r a d a b l e COD, a c c o r d i n g t o t h e t h e o r y o f van H a a n d e l e t a l . (1981) ( i . e . 8.6 mg COD/mg NO3-N) was d e r i v e d i n the f o l l o w i n g way: A c c o r d i n g t o t h e b i o l o g i c a l g r o w t h k i n e t i c t h e o r y of M a r a i s and Ekama ( 1 9 7 6 ) , f o r e v e r y mg o f COD u t i l i z e d u n d e r a e r o b i c c o n d i t i o n s , ( l - P Y n ) mg o f oxygen a r e r e q u i r e d , where P i s t h e COD/VSS r a t i o o f t h e s l u d g e = 1.48 mg COD/mg VSS and Y h i s t h e y i e l d c o e f f i c i e n t f o r h e t e r o t r o p h i c o r g a n i s m s = 0.45 a t 2 0 ° C . B o t h o f t h e s e c o n s t a n t s were d e t e r m i n e d e x p e r i m e n t a l l y . T h e r e f o r e , n u m e r i c a l l y ( 1-1.48X0.45) = 0 .33 mg of oxygen a r e r e q u i r e d f o r e v e r y mg o f COD u t i l i z e d by t h e o r g a n i s m s o f t h e p r o c e s s . E q u a t i n g t h e e l e c t r o n e q u i v a l e n c e of n i t r a t e and oxygen, 2.8 g n i t r a t e ( as N) = 8.0 g oxy g e n ( a s 0 ) . T hus t h e -125-n i t r a t e consumption p e r u n i t mass of COD o x i d i z e d = 0.33 X 8.0/2.8 = 0.116 mg N/mg COD. C o n v e r s e l y , 8.6 mg of COD a r e m e t a b o l i z e d f o r every mg of NO3-N reduced. From the above d e r i v a t i o n i t i s c l e a r t h a t the s u b s t r a t e r e q u i r e m e n t f o r d e n i t r i f i c a t i o n , as e s t i m a t e d by van Haandel e t a l . (1981), i s not based on the s t o i c h i o m e t r y of de n i t r i f i c a t i o n b ut r a t h e r on the biomass y i e l d f a c t o r f o r the a e r o b i c o x i d a t i o n of any carbonaceous s u b s t r a t e and the s t o i c h i o m e t r i c e q u i v a l e n c e of n i t r a t e and oxygen. However, an a l t e r n a t i v e approach i s to e s t i m a t e the r e q u i r e d mass of a p a r t i c u l a r s u b s t r a t e , such as a c e t a t e , i n the d e n i t r i f i c a t i o n of a g i v e n mass of n i t r a t e u s i n g a s t o i c h i o m e t r i c a l l y b a l a n c e d e q u a t i o n . The f o l l o w i n g e q u a t i o n f o r the d e n i t r i f i c a t i o n of n i t r a t e ( i n t h i s case n i t r a t e s e r v e s as the t e r m i n a l e l e c t r o n a c c e p t o r ) u s i n g a c e t a t e as the e l e c t r o n donor i s d e r i v e d from the work of McCarty e t a l . ( 19 69) u s i n g a consumptive r a t i o ( d e f i n e d as the r a t i o of the t o t a l mass of s u b s t r a t e consumed d u r i n g d e n i t r i f i c a t i o n t o the s t o i c h i o m e t r i c r e q u i r e m e n t f o r d e n i t r i f i c a t i o n and d e o x y g e n a t i o n a l o n e ) , Cr=1.30: 0.771 CH3COO"+ NO3 => 0.475 N 2 + 1.288 C 0 2 + 1.670 OH" + 0.144 H 20 + 0.051 C 5 H 7 0 2 N From the above e q u a t i o n , 0.771 moles of a c e t a t e a r e o x i d i z e d f o r ev e r y mole of n i t r a t e d e n i t r i f i e d . E x p r e s s i n g the a c e t a t e i n the COD e q u i v a l e n c e form, 3.53 mg of a c e t a t e (as COD) a r e u t i l i z e d f o r e v e r y mg of n i t r a t e (as N) d e n i t r i f i e d . T h i s r a t i o i s -126-e x t r e m e l y c l o s e ( w i t h i n 2%) of the r a t i o d e t e r m i n e d i n t h i s r e s e a r c h by q u a n t i f y i n g the d e t r i m e n t a l e f f e c t of the presence of n i t r a t e on the a n a e r o b i c P r e l e a s e mechanism, and the a c e t a t e / phosphorus molar exchange r a t i o i n the c o n t r o l r e a c t o r of the same ex p e r i m e n t . I t f o l l o w s , t h e r e f o r e , t h a t the model of S i e b r i t z e t a l . ( 1982) o v e r e s t i m a t e s the d e t r i m e n t a l e f f e c t of n i t r a t e by assuming t h a t the r e a d i l y b i o d e g r a d a b l e COD r e q u i r e d f o r the e x c e s s b i o l o g i c a l P removal mechanism i s u t i l i z e d p r e f e r e n t i a l l y i n the d e n i t r i f i c a t i o n r e a c t i o n a t a r a t e of 8.6 mg COD p e r mg of n i t r a t e (as N) e n t e r i n g the a n a e r o b i c zone of the p r o c e s s . W i t h r e g a r d t o the s i m u l t a n e o u s use of the a v a i l a b l e s u b s t r a t e i n b o t h the e x c e s s b i o l o g i c a l P removal mechanism and the d e n i t r i f i c a t i o n r e a c t i o n , the b a t c h t e s t i n g r e p o r t e d i n t h i s t h e s i s shows an i n t e r e s t i n g phenomenon. When n i t r a t e i s p r e s e n t i n an u n a e r a t e d f l a s k , of a c t i v a t e d s l u d g e , the P r e l e a s e mechanism i s v i r t u a l l y u n a f f e c t e d , p r o v i d e d t h a t t h e r e e x i s t s an e x c e s s c o n c e n t r a t i o n of a carbonaceous s u b s t r a t e such as a c e t a t e . However, as soon as the s u b s t r a t e becomes l i m i t i n g , the P r e l e a s e mechanism i s r e v e r s e d and P uptake i m m e d i a t e l y commences. T h i s o b s e r v a t i o n was c o n f i r m e d i n the work of Comeau ( 1984) who i n j e c t e d a sodium n i t r a t e s o l u t i o n i n t o a s e r i e s of a n a e r o b i c b a t c h f l a s k s i n which a n a e r o b i c P r e l e a s e had been induced t h r e e hours p r e v i o u s l y by the a d d i t i o n of a c e t a t e . At the time of the n i t r a t e a d d i t i o n , the r a p i d P r e l e a s e phase was complete and s u b s t r a t e l i m i t i n g c o n d i t i o n s p r e v a i l e d i n the f l a s k s . -127-I m m e d i a t e l y upon i n j e c t i o n o f t h e n i t r a t e s o l u t i o n , P u p t a k e commenced and c o n t i n u e d f o r t h e p e r i o d w h i l e n i t r a t e was p r e s e n t i n t h e f l a s k s . As s o o n a s d e n i t r i f i c a t i o n was c o m p l e t e , P r e l e a s e once a g a i n resumed a t a somewhat l o w e r r a t e . From t h e s e o b s e r v a t i o n s , Comeau ( 1984) c o n c l u d e d t h a t a t l e a s t a f r a c t i o n of-t h e o r g a n i s m s i n v o l v e d i n e x c e s s b i o l o g i c a l P r e m o v a l were c a p a b l e o f d e n i t r i f i c a t i o n and t h e r e f o r e , had t h e a b i l i t y t o a c c u m u l a t e p o l y p h o s p h a t e i n the p r e s e n c e o f n i t r a t e and w o u l d be c a p a b l e o f s u c h a c c u m u l a t i o n i n the a n o x i c zone o f n u t r i e n t r e m o v a l p r o c e s s e s . F u r t h e r m o r e , Comeau ( 1984) o b s e r v e d t h e d i s a p p e a r a n c e o f PHB from t h e s l u d g e d u r i n g t h e de n i t r i f i c a t i o n i n the a b s e n c e o f e x c e s s s u b s t r a t e and c o n c l u d e d t h a t t h e i n t r a c e l l u l a r l y s t o r e d PHB s e r v e s a s t h e c a r b o n s o u r c e f o r d e n i t r i f i c a t i o n . I n t h i s way, t h e c a r b o n p l a y s a d u a l r o l e i n t h e n u t r i e n t r e m o v a l p r o c e s s . F i r s t l y , i t i s s t o r e d u n d e r a n a e r o b i c c o n d i t i o n s , t h e r e b y i n i t i a t i n g t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism and t h e n , u n d e r s u b s e q u e n t a n o x i c c o n d i t i o n s , i t i s u t i l i z e d a s t h e c a r b o n s o u r c e f o r d e n i t r i f i c a t i o n . The i n c o r p o r a t i o n o f t h i s d u a l f u n c t i o n o f s h o r t c h a i n VFA's and o t h e r s o u r c e s o f " r e a d i l y b i o d e g r a d a b l e COD" has p r o v e d t o be h i g h l y s u c c e s s f u l i n t h e d e s i g n of p r o c e s s e s f o r t h e s i m u l t a n e o u s r e m o v a l o f b o t h P and N, s u c h a s t h e Bardenpho and UCT t y p e p r o c e s s e s , i n w h i c h s i g n i f i c a n t amounts o f P u p t a k e o c c u r i n t h e a n o x i c zone o f t h e p r o c e s s . The r e s e a r c h u s i n g t h e UCT p r o c e s s r e p o r t e d i n t h i s t h e s i s ( S e c t i o n 7.2, C h a p t e r 7) c o n f i r m s t h e f i n d i n g s of F l o r e n t z and G r a n g e r ( 1982), S i e b r i t z e t a l . ( 1983 ), Comeau e t a l . ( 1985b) - 1 2 8 -a n d o t h e r s t h a t P u p t a k e i s a n a n o x i c a s w e l l a s a n a e r o b i c p h e n o m e n o n , i . e . t h a t s i g n i f i c a n t m a s s e s o f P a r e t a k e n u p i n t h e p r e s e n c e o f n i t r a t e ( b u t i n t h e a b s e n c e o f d i s s o l v e d o x y g e n ) i n p r o c e s s e s t h a t a r e d e s i g n e d t o i n c l u d e b o t h n i t r i f i c a t i o n a n d d e n i t r i f i c a t i o n . T h e m e a n P c o n c e n t r a t i o n a n d t h e n e t c h a n g e i n P c o n c e n t r a t i o n , A P ( e x p r e s s e d a s m g P / L o f i n f l u e n t f l o w ) f o r e a c h o f t h e r e a c t o r s i n t h e e x p e r i m e n t s u s i n g t h e U C T p r o c e s s i n C h a p t e r S e v e n a r e p r e s e n t e d i n T a b l e 8 . 1 . T h e A P v a l u e s f o r e a c h r e a c t o r w e r e c a l c u l a t e d o n t h e b a s i s o f a m a s s b a l a n c e f o r t h e r e a c t o r , w i t h n e g a t i v e v a l u e s i n d i c a t i n g P r e l e a s e a n d p o s i t i v e v a l u e s i n d i c a t i n g P u p t a k e . T a b l e 8 . 1 . M e a n P C o n c e n t r a t i o n s a n d N e t c h a n g e s i n P C o n c e n t r a t i o n i n t h e e x p e r i m e n t s u s i n g t h e U C T p r o c e s s ( S e c t i o n 7 . 2 ) C o n t r o l E x p e r i m e n t R e a c t o r P ( m g / L ) A P ( m g / L ) P ( m g / L ) A P ( m g / L ) I n f l u e n t 3 . 5 4 - 5 . 4 3 A n a e r o b i c 3 . 8 8 - 2 . 0 1 1 0 . 7 8 - 1 0 . 8 6 A n o x i c 2 . 2 1 + 1 . 6 8 5 . 2 7 + 5 . 3 2 A e r o b i c 1 . 8 2 + 1 . 9 5 1 . 5 9 + 9 . 2 0 C l a r i f i e r 1 . 7 2 + 0 . 2 0 1 . 4 7 + 0 . 3 0 S y s t e m P R e m o v a l 1 . 8 2 3 . 9 6 F r o m t h e a b o v e t a b l e , i t i s c l e a r t h a t i n b o t h e x p e r i m e n t s c o n d u c t e d o n t h e U C T p r o c e s s , a s i g n i f i c a n t d e g r e e o f P u p t a k e o c c u r r e d i n t h e a n o x i c r e a c t o r o f t h e p r o c e s s . I n t h e c o n t r o l p e r i o d , w h e r e a s m a l l d e g r e e o f e x c e s s b i o l o g i c a l P r e m o v a l t o o k p l a c e , b u t w h e r e t h e c o m b i n e d n i t r a t e - r i c h m i x e d l i q u o r f l o w w a s e g u i v a l e n t t o f o u r t i m e s t h e i n f l u e n t f l o w r a t e , a p p r o x i m a t e l y 4 4 % o f t h e P u p t a k e o c c u r r e d i n t h e a n o x i c z o n e o f t h e p r o c e s s . I n t h e e x p e r i m e n t a l p e r i o d , p r i m a r y s l u d g e f e r m e n t a t i o n w a s -129-i n c o r p o r a t e d i n t o the d e s i g n of the p r o c e s s and the system P r emoval, as w e l l as the degree of a n a e r o b i c P r e l e a s e , i n c r e a s e d s i g n i f i c a n t l y . The t o t a l r e c y c l e from the end of the p r o c e s s t o the a n o x i c r e a c t o r was reduced to 1.5 t i m e s the i n f l u e n t f l o w r a t e and the percentage of P uptake o c c u r r i n g i n t h a t r e a c t o r was about 36%. I t i s i m p o r t a n t to n o t e t h a t i n b o t h of these e x p e r i m e n t s the a n o x i c r e a c t o r o n l y comprised about 2 0% of the t o t a l p r o c e s s volume and t h a t a n o x i c P uptake was, t h e r e f o r e , o c c u r r i n g a t a r a p i d r a t e . I t i s known t h a t f o r many a e r o b i c o rganisms, i n the absence of d i s s o l v e d oxygen, n i t r a t e r e a d i l y r e p l a c e s oxygen as the t e r m i n a l e l e c t r o n a c c e p t o r , l a r g e l y because the m e t a b o l i c pathway f o r n i t r a t e i s s i m i l a r to t h a t f o r oxygen. Chang and M o r r i s (1972) found t h a t the replacement of oxygen w i t h n i t r a t e as the t e r m i n a l e l e c t r o n a c c e p t o r i s f a c i l i t a t e d by the f o r m a t i o n of an enzyme, n i t r a t a s e , whose p r o d u c t i o n i s i n h i b i t e d by the presence of d i s s o l v e d oxygen. I t seems l i k e l y , t h e r e f o r e , t h a t a s i g n i f i c a n t number of organisms i n v o l v e d i n the e x c e s s b i o l o g i c a l P removal mechanism a r e a l s o c a p able of d e n i t r i f i c a t i o n and t h a t t h e r e a r e s i g n i f i c a n t advantages i n i n c o r p o r a t i n g an a n o x i c r e a c t o r i n t o the d e s i g n of the a c t i v a t e d s l u d g e p r o c e s s where b o t h d e n i t r i f i c a t i o n and P uptake can o c c u r s i m u l t a n e o u s l y . 8.4. P r i m a r y Sludge F e r m e n t a t i o n Research u s i n g the p i l o t - s c a l e p r i m a r y s l u d g e f e r m e n t e r c l e a r l y showed t h a t the two most e f f i c i e n t s u b s t r a t e s f o r i n d u c i n g a n a e r o b i c P r e l e a s e i n the a c t i v a t e d s l u d g e p r o c e s s , a c e t a t e and p r o p i o n a t e , can be produced o n - s i t e by p r i m a r y sludge -130-fe r m e n t a t i o n . I t was found t h a t the VFA y i e l d (measured as mg HAc per mg of p r i m a r y sludge COD e n t e r i n g the fermenter) was o p t i m a l i n the 3.5-5.0 day sludge age range a t about 0.09 mg HAc/mg COD, w i t h p r o d u c t i o n d r o p p i n g o f f s l i g h t l y a t s h o r t e r and l o n g e r sludge ages. I t s h o u l d be note d , however, t h a t the drop i n p r o d u c t i o n observed a t a sludge age of 2.5 days may be a t t r i b u t e d to the lower f e r m e n t e r o p e r a t i n g temperature d u r i n g t h a t p e r i o d . With r e g a r d to t h e e f f e c t of te m p e r a t u r e , i n c r e a s i n g the o p e r a t i n g temperature of a f e r m e n t e r o p e r a t i n g a t a 3.5 day sludge age from about 12°C to about 2 0°C o n l y i n c r e a s e d the VFA y i e l d by about 2 0%, which i s c o n s i d e r a b l y l e s s than t h a t p r e d i c t e d by the g e n e r a l t h e o r y of m i c r o b i a l a c t i v i t y . Attempts to r a i s e the o p e r a t i n g pH of the f e r m e n t e r t o a v a l u e of about 7.0 u s i n g sodium h y d r o x i d e d i d not r e s u l t i n any improvement i n the VFA y i e l d , w i t h the sludge age and o p e r a t i n g temperature r e m a i n i n g c o n s t a n t . I t s h o u l d be noted t h a t i n t h i s f e r m e n t a t i o n study the s o l i d s c o n c e n t r a t i o n and temperature c o n t r o l , as w e l l as the pH adj u s t m e n t , were poor and, t h e r e f o r e , a d d i t i o n a l p i l o t - s c a l e r e s e a r c h i s s t i l l r e q u i r e d i n o r d e r to a c c u r a t e l y determine the e f f e c t of these v a r i a b l e s on VFA p r o d u c t i o n . The r e s u l t s of the f e r m e n t a t i o n study were c o n f i r m e d by the f i n d i n g s of Gupta e t a l . (1985), who c a r r i e d out a comprehensive l a b o r a t o r y s c a l e p r i m a r y sludge f e r m e n t a t i o n study u s i n g " f i l l and draw" s e a l e d r e a c t o r s to measure the e f f e c t s of temp e r a t u r e , pH and d e t e n t i o n time on VFA p r o d u c t i o n . These r e s e a r c h e r s found t h a t , a l t h o u g h t h e r e was much i n t e r a c t i o n between the t h r e e -131-v a r i a b l e s examined, c e r t a i n c l e a r t r e n d s emerged. F o r example, t h e y f o u n d t h a t VFA p r o d u c t i o n improved c o n s i s t e n t l y w i t h i n c r e a s i n g t e m p e r a t u r e i n the 1 0 - 3 0 ° C t e m p e r a t u r e r a n g e . I n g e n e r a l , optimum a c i d p r o d u c t i o n was a c h i e v e d a t a 6 day d e t e n t i o n time w i t h a s l i g h t i n c r e a s e i n p r o d u c t i o n a t a 10 day d e t e n t i o n time a t 10 and 2 0 ° C and a d e c r e a s e i n p r o d u c t i o n a t 3 0 ° C . However, t h e s e t r e n d s a r e b a s e d o n n e t a c i d p r o d u c t i o n v a l u e s and i t i s p o s s i b l e t h a t a t 3 0 ° C and a 10 day s l u d g e age, more a c i d was p r o d u c e d b u t s u b s e q u e n t l y c o n v e r t e d t o CH4 and CO2 by m e t h o g e n i c o r g a n i s m s . They a l s o f o u n d t h a t c o n t r o l l i n g t h e pH t o a l e v e l o f 7.0 d i d n o t r e s u l t i n an i n c r e a s e i n VFA p r o d u c t i o n b u t t h a t , a s i n the c a s e of t h e r e s e a r c h r e p o r t e d i n t h i s t h e s i s , no r i g o r o u s s t u d y i n t o the e f f e c t of pH was c a r r i e d o u t u s i n g a range of pH v a l u e s . A c o m p a r i s o n was made o n l y between an u n c o n t r o l l e d pH c o n d i t i o n and c o n t r o l l i n g t h e pH a t one p a r t i c u l a r l e v e l . I t i s c l e a r t h a t a c o m p r e h e n s i v e p i l o t - s c a l e s t u d y of VFA p r o d u c t i o n by p r i m a r y s l u d g e f e r m e n t a t i o n a t s l u d g e a g e s i n t h e r a n g e o f 1-6 d a y s , t o g e t h e r w i t h t h e i n t e r a c t i o n of t h e e f f e c t s of t e m p e r a t u r e , i s s t i l l r e q u i r e d i n o r d e r t o a c c u r a t e l y e v a l u a t e t h e e c o n o m i c s of the b e s t c o m b i n a t i o n o f s l u d g e age and t e m p e r a t u r e . In a d d i t i o n , ways of s i m p l i f y i n g t h e d e s i g n and o p e r a t i o n o f the f e r m e n t e r so t h a t t h e f e r m e n t e r volume r e q u i r e m e n t s can be m i n i m i z e d and t h e need f o r a f e r m e n t e r s e c o n d a r y c l a r i f i e r e l i m i n a t e d must s t i l l be e x amined (See S e c t i o n 8 . 6 ) . -132-8.5. The Use of P r i m a r y S l u d g e F e r m e n t a t i o n i n t h e N u t r i e n t Removal A c t i v a t e d S l u d g e P r o c e s s The r e s u l t s o f C h a p t e r Seven c l e a r l y show t h a t , i n a d d i t i o n t o b e i n g a b l e t o p r o d u c e the s p e c i f i c s u b s t r a t e s r e q u i r e d i n the a c t i v a t e d s l u d g e p r o c e s s f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism t o o p e r a t e , t h e s e s u b s t r a t e s c a n be p r o d u c e d i n s u f f i c i e n t q u a n t i t i e s t o s i g n i f i c a n t l y enhance t h e P r e m o v a l c h a r a c t e r i s t i c s o f the p r o c e s s . The P r e m o v a l e f f i c i e n c y ( a s measured by the AP/ACOD r e m o v a l r a t i o ) and t h e d r y w e i g h t p e r c e n t P c o n t e n t o f the s l u d g e were b o t h d o u b l e d by t h e i n c o r p o r a t i o n o f p r i m a r y s l u d g e f e r m e n t a t i o n i n t o t h e d e s i g n o f a s i m p l e u n a e r a t e d / a e r a t e d p r o c e s s c o n f i g u r a t i o n t h a t p r e v i o u s l y d i d n o t e x h i b i t e x c e s s b i o l o g i c a l P r e m o v a l . S i m i l a r l y , t h e P r e m o v a l c h a r a c t e r i s t i c s of a UCT p r o c e s s c o n f i g u r a t i o n t h a t was e x h i b i t i n g some d e g r e e o f e x c e s s b i o l o g i c a l P r e m o v a l were improved by ab o u t 5 0% by t h e use of p r i m a r y s l u d g e f e r m e n t a t i o n . T h e s e r e s u l t s p o i n t t o the i n c r e a s i n g r e a l i z a t i o n o f t h e i m p o r t a n c e o f the n a t u r e o f t h e COD e n t e r i n g t h e p r o c e s s r a t h e r t h a n s i m p l y c o n s i d e r i n g t h e t o t a l i n f l u e n t COD c o n c e n t r a t i o n . F o r example, the i n c o r p o r a t i o n o f p r i m a r y c l a r i f i c a t i o n and p r i m a r y s l u d g e f e r m e n t a t i o n l o w e r s the mass o f COD e n t e r i n g t h e p r o c e s s due t o t h e i n e f f i c i e n t c o n v e r s i o n o f t h e p r i m a r y s l u d g e COD i n t o s i m p l e r o r g a n i c s , f e r m e n t e r s l u d g e w a s t a g e , e t c . However, i n s p i t e o f the l o w e r mass o f COD e n t e r i n g t h e p r o c e s s , t h e waste s t r e a m COD i s p r e p r o c e s s e d i n t o a form t h a t i s f a r more s u i t a b l e f o r e x c e s s b i o l o g i c a l P r e m o v a l . The complex o r g a n i c m a t e r i a l i s removed i n the p r i m a r y c l a r i f i e r and from i t s i m p l e r s h o r t c h a i n v o l a t i l e f a t t y a c i d s , t h e p r i n c i p l e s u b s t r a t e s -133-r e q u i r e d f o r the e x c e s s b i o l o g i c a l P r e m o v a l mechanism i n t h e s u b s e q u e n t a c t i v a t e d p r o c e s s , a r e p r o d u c e d . T h i s form o f p r e t r e a t m e n t p a r t i a l l y c o m pensates f o r t h e p r o b l e m s a s s o c i a t e d w i t h the o p e r a t i o n o f p l a n t s d e s i g n e d f o r e x c e s s b i o l o g i c a l P r e m o v a l t h a t t r e a t low o r g a n i c s t r e n g t h w a s t e w a t e r s , a s t y p i c a l l y f o u n d i n N o r t h A m e r i c a . I t s h o u l d be n o t e d t h a t i n a r e a s h a v i n g warm t e m p e r a t e c l i m a t e s and sewer l i n e s w i t h l o n g h y d r a u l i c d e t e n t i o n t i m e s , a c o n s i d e r a b l e d e g r e e o f t h i s p r e - t r e a t m e n t may o c c u r i n t h e sewage c o l l e c t i o n s y s t e m , p r i o r t o t h e w a s t e w a t e r e n t e r i n g the t r e a t m e n t p l a n t . E x t e n s i v e i n v e s t i g a t i o n o f t h e n a t u r e o f the b i o d e g r a d a b l e COD p r e s e n t i n a waste s t r e a m , w i t h p a r t i c u l a r r e f e r e n c e t o t h e s p e c i f i c s u b s t r a t e s r e q u i r e d by t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism s h o u l d , t h e r e f o r e , be c a r r i e d o u t i n the p l a n n i n g s t a g e s of a l l p l a n t s i n which t h i s mechanism i s t o be e n c o u r a g e d . T h i s s h i f t i n emphasis towards the i m p o r t a n c e o f c h a r a c t e r i z i n g the b i o d e g r a d a b l e components of the i n f l u e n t COD has, t o a c e r t a i n e x t e n t , made i n f l u e n t c h a r a c t e r i z a t i o n i n terms of t h e P/COD and TKN/COD r a t i o s l a r g e l y i n v a l i d , a s t h e s e r a t i o s a r e b a s e d on t h e t o t a l COD p r e s e n t i n th e w a s t e w a t e r and d i s r e g a r d t h e c h e m i c a l n a t u r e o f t h e b i o d e g r a d a b l e COD components. A r a t i o n a l d e s i g n p r o c e d u r e t h a t i n c l u d e s t h e r e c e n t u n d e r s t a n d i n g o f t h e p r e r e q u i s i t e s of e x c e s s b i o l o g i c a l P r e m o v a l w i t h r e g a r d t o t h e s p e c i f i c s u b s t r a t e r e q u i r e d f o r t h e e x c e s s b i o l o g i c a l P r e m o v a l mechanism to o p e r a t e i s , t h e r e f o r e , s t r o n g l y recommended. P r i m a r y s l u d g e f e r m e n t a t i o n has been u s e d t o enha n c e the P r e m o v a l c h a r a c t e r i s t i c s of a number o f f u l l - s c a l e n u t r i e n t -134-removal p r o c e s s e s . Oldham (1984) p r e s e n t e d d a t a on the b e n e f i t s of d i s c h a r g i n g l i q u o r from the p r i m a r y s l u d g e t h i c k e n e r i n t o the a n a e r o b i c zone of the 5-stage Bardenpho p l a n t a t Kelowna B.C., Canada. The p l a n t c o n s i s t s of two p a r a l l e l modules and when a l l of the V F A - r i c h f e r m e n t e r l i q u o r ( the t h i c k e n e r sludge b l a n k e t h e i g h t i s c o n t r o l l e d i n an attempt t o maximize the VFA p r o d u c t i o n ) was a l t e r n a t e l y d i s c h a r g e d i n t o one of the two modules, the module r e c e i v i n g the l i q u o r d i s c h a r g e i m m e d i a t e l y e x h i b i t e d a g r e a t e r degree of a n a e r o b i c P r e l e a s e and e x c e l l e n t system P removal w i t h i n a few days. At the same t i m e , the a n a e r o b i c P r e l e a s e and system P removal r a p i d l y d e c l i n e d i n the module from which the t h i c k e n e r l i q u o r d i s c h a r g e was withdrawn. In the f i n a l s t a g e s of the e x p e r i m e n t , when the t h i c k e n e r l i q u o r was e v e n l y d i s t r i b u t e d between the two modules, e f f l u e n t o rtho-P c o n c e n t r a t i o n s of l e s s than 1 mg/L were a c h i e v e d on both s i d e s of the p l a n t w i t h i n about 4 days of o p e r a t i o n . The p l a n t has been o p e r a t e d s u c c e s s f u l l y u s i n g t h i s form of p r i m a r y sludge f e r m e n t a t i o n , w i t h mean e f f l u e n t t o t a l P c o n c e n t r a t i o n s of l e s s than 1 mg/L b e i n g a c h i e v e d f o r extended p e r i o d s of t i m e . T h i s i s i n s p i t e of the f a c t t h a t a p p l i c a t i o n of the UCT b i o l o g i c a l P removal model p r e d i c t s t h a t no e x c e s s b i o l o g i c a l P removal w i l l o c c u r i n the p l a n t t r e a t i n g raw sewage ( B a r n a r d , 1985). N i c h o l l s e t a l . ( 1984) found t h a t i t was p o s s i b l e t o g e n e r a t e 73 mg/L of VFA ( e x p r e s s e d as mg HAc p e r l i t r e of i n f l u e n t f l o w ) by f e r m e n t i n g p r i m a r y sludge i n an a c i d d i g e s t e r w i t h a 3 day r e t e n t i o n time a t the N o r t h e r n Works 5-stage Bardenpho p l a n t i n Johannesburg, South A f r i c a . By d i s c h a r g i n g the s u p e r n a t a n t from -135-t h e a c i d d i g e s t e r i n t o the a n a e r o b i c zone of the p r o c e s s , they were a b l e to a c h i e v e an e f f l u e n t o rtho-P c o n c e n t r a t i o n of 2.2 mg/L ( i n f l u e n t t o t a l P = 17.5 mg/L) i n the p r o c e s s . By measuring the " r e a d i l y b i o d e g r a d a b l e COD" c o n c e n t r a t i o n i n the a n a e r o b i c zone of the p r o c e s s u s i n g the d e n i t r i f i c a t i o n method o u t l i n e d i n t h e i r paper, N i c h o l l s e t a l . were a b l e t o demonstrate the d i s a p p e a r a n c e of the s u b s t r a t e under a n a e r o b i c c o n d i t i o n s and the p e r c e i v e d r o l e of the s u b s t r a t e i n the e x c e s s b i o l o g i c a l P removal mechanism. 8.6. F u t u r e Design and O p e r a t i o n a l C o n s i d e r a t i o n s In t h i s r e s e a r c h i t was c l e a r l y demonstrated t h a t the P removal c h a r a c t e r i s t i c s of the n u t r i e n t removal p r o c e s s can be s i g n i f i c a n t l y enhanced by the i n c o r p o r a t i o n of p r i m a r y s l u d g e f e r m e n t a t i o n i n t o the p r o c e s s d e s i g n . The use of p r i m a r y s l u d g e f e r m e n t a t i o n , t h e r e f o r e , shows g r e a t p o t e n t i a l as a v i a b l e method of g e n e r a t i n g the s p e c i f i c s u b s t r a t e s r e q u i r e d t o ensure t h a t e x c e s s b i o l o g i c a l P removal t a k e s p l a c e i n f u t u r e a c t i v a t e d s l u d g e p r o c e s s e s and i n e x i s t i n g p l a n t s t h a t undergo r e t r o f i t t i n g f o r such removal. P r i m a r y s e d i m e n t a t i o n and p r i m a r y s l u d g e d i g e s t i o n are commonly i n c o r p o r a t e d i n t o the d e s i g n of c o n v e n t i o n a l a c t i v a t e d s l u d g e p r o c e s s e s as a means of r e d u c i n g the o r g a n i c l o a d i n g and, t h e r e f o r e , the oxygen r e q u i r e m e n t s of the p r o c e s s . In such c a s e s , the a d d i t i o n of p r i m a r y s l u d g e f e r m e n t a t i o n t o produce VFA's o n - s i t e f o r e x c e s s b i o l o g i c a l P removal would be a r e l a t i v e l y s i m p l e m o d i f i c a t i o n . In the p l a n n i n g of new p l a n t s , the p r i m a r y sludge t r e a t m e n t equipment can e a s i l y be d e s i g n e d to p r o v i d e f o r a c i d f e r m e n t a t i o n , w i t h -136-the a c i d - r i c h f e r m e n t e r l i q u o r b e i n g d i s c h a r g e d i n t o the a n a e r o b i c zone of the p r o c e s s . E x i s t i n g p l a n t s , p a r t i c u l a r l y those a l r e a d y having p r i m a r y c l a r i f i c a t i o n , can e a s i l y be r e t r o f i t t e d t o i n c l u d e these d e s i g n f e a t u r e s by a d a p t i n g the e x i s t i n g p r i m a r y sludge t r e a t m e n t f a c i l i t i e s i n o r d e r to o p t i m i z e VFA p r o d u c t i o n . The a e r a t i o n tank of the main p r o c e s s would have to be m o d i f i e d to i n c l u d e an a n a e r o b i c zone, i . e . a zone t h a t r e c e i v e s no d i s s o l v e d oxygen and minimal n i t r a t e l o a d i n g i n the sludge r e c y c l e , i f n i t r i f i c a t i o n i s a n t i c i p a t e d i n the a e r o b i c zone of the p r o c e s s . T h i s zone would r e c e i v e the f e r m e n t e r l i q u o r which would then be a v a i l a b l e s o l e l y f o r the e x c e s s b i o l o g i c a l P removal mechanism. To t h i s end, i t i s i m p o r t a n t t h a t the p r o c e s s c o n f i g u r a t i o n be d e s i g n e d e i t h e r on the p r i n c i p l e of the UCT p r o c e s s , i n which a z e r o n i t r a t e d i s c h a r g e to the a n a e r o b i c zone can be g u a r a n t e e d , o r t h a t i t have a 2-stage a n a e r o b i c zone i n which complete d e n i t r i f i c a t i o n o c c u r s i n the f i r s t stage and the f e r m e n t e r l i q u o r i s d i s c h a r g e d i n t o the second stage of the u n a e r a t e d zone of the p r o c e s s . In t h i s way, organisms having the a b i l i t y t o s t o r e e x c e s s P under a e r o b i c c o n d i t i o n s , and t o s t o r e carbonaceous s u b s t r a t e i n the form of PHB under a n a e r o b i c c o n d i t i o n s , would have a d e c i d e d advantage i n the h i g h l y c o m p e t i t i v e a c t i v a t e d s l u d g e environment. A d d i t i o n a l r e s e a r c h i s s t i l l r e q u i r e d to i n v e s t i g a t e the f e a s i b i l i t y of u s i n g t h i s t e c h n i q u e i n h i g h r a t e a c t i v a t e d s l u d g e p r o c e s s e s , i . e . those d e s i g n e d s p e c i f i c a l l y not to n i t r i f y . T h i s would e l i m i n a t e the problems a s s o c i a t e d w i t h the u t i l i z a t i o n of the s u b s t r a t e s r e q u i r e d f o r the e x c e s s b i o l o g i c a l P removal mechanism -137-i n the d e n i t r i f i c a t i o n r e a c t i o n . U l t i m a t e l y , the d e c i s i o n to i n c l u d e p r i m a r y sludge f e r m e n t a t i o n i n t o the d e s i g n of new works, o r the r e t r o f i t t i n g of e x i s t i n g p l a n t s , i s one t h a t w i l l be made on economic c o n s i d e r a t i o n s . The a n t i c i p a t e d a d d i t i o n a l c a p i t a l and o p e r a t i n g c o s t s must be c a r e f u l l y weighed a g a i n s t the c o s t s of a l t e r n a t i v e methods of enhancing the P removal c h a r a c t e r i s t i c s of the a c t i v a t e d s l u d g e p r o c e s s , e.g. c h e m i c a l p r e c i p i t a t i o n by the i n - p l a n t a d d i t i o n of m e tal s a l t s , a d d i t i o n of a f r e e l y a v a i l a b l e h i g h l y carbonaceous i n d u s t r i a l w astewater r i c h i n the p r e f e r r e d s u b s t r a t e s f o r e x c e s s b i o l o g i c a l P r e m o v a l , sand f i l t r a t i o n of the f i n a l e f f l u e n t t o reduce the t o t a l P c o n c e n t r a t i o n , e t c . I t i s c l e a r t h a t a d d i t i o n a l r e s e a r c h i s r e q u i r e d i n t o the k i n e t i c s of the f e r m e n t a t i o n of p r i m a r y s l u d g e , p a r t i c u l a r l y w i t h r e g a r d to the i n t e r r e l a t i o n s h i p of the s l u d g e age and temperature c o n t r o l p a rameters. I t seems l i k e l y t h a t a s l u d g e age of between 2 and 6 days would s u f f i c e and t h a t s t r i c t c o n t r o l of the s l u d g e age would be r e q u i r e d t o o p t i m i z e the VFA p r o d u c t i o n f o r a l l o p e r a t i n g c o n d i t i o n s . For example, l o n g e r s l u d g e ages may be r e q u i r e d to compensate f o r l o w e r f e r m e n t e r o p e r a t i n g temperatures i n the w i n t e r months. However, i n o r d e r t o o p e r a t e a f e r m e n t e r t h a t r e c e i v e s between 5% and 10% of the i n f l u e n t f l o w a t s l u d g e ages i n t h i s range, a s l u d ge age c o n t r o l s t r a t e g y t h a t i s independent of the h y d r a u l i c d e t e n t i o n time of the f ermenter i s going t o be r e g u i r e d i n o r d e r t o a v o i d i n o r d i n a t e l y l a r g e f e r m e n t e r volumes. T h i s s l u d g e age c o n t r o l s t r a t e g y r e g u i r e s t h a t the f e r m e n t e r have i t s own secondary c l a r i f i e r and sludge -138-r e t u r n r e c y c l e and t h a t fermenter l i q u o r be wasted d a i l y i n some c o n t r o l l e d f a s h i o n , as was c a r r i e d out a t the p i l o t - s c a l e i n the r e s e a r c h r e p o r t e d i n t h i s t h e s i s . An a l t e r n a t i v e method of f e r m e n t e r sludge age c o n t r o l , which e l i m i n a t e s the r e q u i r e m e n t f o r a f e rmenter. seconda ry c l a r i f i e r , i s s c h e m a t i c a l l y p r e s e n t e d i n F i g . 8.2. In t h i s proposed c o n f i g u r a t i o n , p r i m a r y s l u d g e i s pumped from the bottom of the p r i m a r y c l a r i f i e r i n t o a c o m p l e t e l y mixed a n a e r o b i c p r i m a r y sludge f e r m e n t e r , whose l i q u i d s u r f a c e l e v e l i s h i g h e r than t h a t of the p r i m a r y c l a r i f i e r . The f e r m e n t e r mixed l i q u o r i s r e t u r n e d by g r a v i t y , t o g e t h e r w i t h raw i n f l u e n t , back t o the p r i m a r y c l a r i f i e r , which would have t o be d e s i g n e d to handle the increased" so l i d s l o a d i n g . The f e r m e n t e r sludge age would have t o be h y d r a u l i c a l l y c o n t r o l l e d by w a s t i n g the a p p r o p r i a t e volume of mixed l i q u o r from the r e a c t o r d a i l y , s e t t l i n g out and w a s t i n g the s o l i d s , and d i s c h a r g i n g the f e r m e n t e r s u p e r n a t a n t i n t o the f e r m e n t e r e f f l u e n t stream. A major p e r c e i v e d advantage of t h i s approach o v e r the " s i d e s t r e a m " method used i n t h i s t h e s i s i s t h a t a l l of the i n f l u e n t f l o w i s brought i n t o c o n t a c t w i t h the fermented s o l i d s , t h e r e b y m a x i m i z i n g the o p p o r t u n i t y f o r VFA p r o d u c t i o n i n the p r i m a r y c l a r i f i e r and i n the f e r m e n t e r i t s e l f . I n a d d i t i o n , t h i s method a l l o w s f o r the removal of the p r i m a r y s l u d g e from the wastewater, t h e r e b y d e c r e a s i n g the d i s s o l v e d oxygen r e g u i r e m e n t s of the p r o c e s s , w h i l e a t the same time, the VFA c o n t e n t of the s e t t l e d sewage i s maximized, thereby enhancing the P removal c h a r a c t e r i s t i c s of the p r o c e s s . T h i s d e s i g n s t r a t e g y i s s i m i l a r i n c o n c e p t t o the " a c t i v a t e d p r i m a r y t a n k s " recommended by PRIMARY SLUDGE F E R M E N T E R F E R M E N T E R E F F L U E N T COMBINED WITH RAW I N F L U E N T INFLUENT F E R M E N T E R MIXED LIQUOR W A S T A G E -D E T E R M I N E S F E R M E N T E R S R T A C T I V A T E D S L U D G E P R O C E S S CONFIGURATION DESIGNED FOR E N H A N C E D BIOLOGICAL P R E M O V A L E F F L U E N T SEWAGE TO BIOREACTOR j PRI IMARY SLUDGE-PUMPING RATE DETERMINES F E R M E N T E R HRT Fig. 8.2. Schematic layout of proposed method of operating primary sludge fermenter having independent SRT and HRT control and no fermenter secondary c l a r i f i e r -140-Barnard ( 1984), e x c e p t t h a t i t a l l o w s f o r s i g n i f i c a n t l y more s t r i n g e n t c o n t r o l o v e r the o p e r a t i n g s l u d g e age of the f e r m e n t e r , thereby f a c i l i t a t i n g the o p t i m i z a t i o n of VFA p r o d u c t i o n f o r d i f f e r e n t o p e r a t i n g c o n d i t i o n s . With r e g a r d t o the most s u i t a b l e a c t i v a t e d sludge p r o c e s s c o n f i g u r a t i o n f o r t h i s proposed s t r a t e g y , i t i s recommended t h a t the UCT p r o c e s s be chosen as i t g u a r a n t e e s a z e r o n i t r a t e d i s c h a r g e t o the a n a e r o b i c zone a t the head end of the p r o c e s s and, t h e r e f o r e , a l l of the VFA g e n e r a t e d by p r i m a r y sludge f e r m e n t a t i o n w i l l be a v a i l a b l e f o r the e x c e s s b i o l o g i c a l P removal mechanism. I f , however, r e l a t i v e l y low e f f l u e n t n i t r a t e c o n c e n t r a t i o n s of around 3 mg N/L a r e a n t i c i p a t e d , the Bardenpho-type p r o c e s s c o n f i g u r a t i o n s w i l l a l s o be s u i t a b l e , as the mass of s u b s t r a t e r e q u i r e d f o r d e n i t r i f i c a t i o n s h o u l d not s i g n i f i c a n t l y a f f e c t the P removal c h a r a c t e r i s t i c s of the p r o c e s s . The r e s u l t s of t h i s r e s e a r c h a l s o demonstrate the importance of the dry weight p e r c e n t P c o n t e n t of the s l u d g e as a p o t e n t i a l p r o c e s s c o n t r o l parameter. Because d a i l y s l u d g e wastage from the a e r o b i c zone i s the p r i n c i p l e method f o r removing P from the p r o c e s s , i t f o l l o w s t h a t the P c o n t e n t of the s l u d g e i n the a e r o b i c zone of the p r o c e s s i s an e x c e l l e n t measure of the degree t o which the p r o c e s s i s e x h i b i t i n g e x c e s s b i o l o g i c a l P removal. P r o c e s s e s not e x h i b i t i n g any e x c e s s b i o l o g i c a l P removal are g e n e r a l l y found to have a s l u d g e d r y weight p e r c e n t P c o n t e n t of 1.5%, i . e . the P r e g u i r e m e n t s f o r b a s i c m e t a b o l i c purposes (Hoffmann and M a r a i s , 1977). F i g . 8.3 shows, on the b a s i s of a P mass bal a n c e of the p r o c e s s , how the mean dry weight I I I I I I I I I 2 4 6 8 10 12 14 16 18 2 0 2 2 2 4 2 6 2 8 3 0 3 2 3 4 3 6 3 8 4 0 X I 0 " 4 Q x AP V p x M L S S < mS/mg.day) 8 . 3 . Mass ba lance c h a r t showing the dependence of t h e d r y w e i g h t p e r c e n t P c o n t e n t o f t h e s ludge on v a r i o u s p r o c e s s pa ramete rs and the s ludge age, where : Q = d a i l y i n f l u e n t f l o w ( L / D ) ; AP=system P r e m o v a l ( m g / L ) ; Vp=process volume ( L ) ; MLSS=mixed l i q u o r suspended s o l i d s ( m g / L ) . -142-p e r c e n t P c o n t e n t o f the sludge v a r i e s w i t h the mass of system P removal p e r u n i t mass of sl u d g e i n the p r o c e s s , as a f u n c t i o n of the sl u d g e age of the p r o c e s s . For example, f o r a p r o c e s s t o e x h i b i t a system P removal of 20 X 10~^ mg P p e r mg of MLSS per day i n a p r o c e s s b e i n g o p e r a t e d a t a sl u d g e age of 15 days, the mean dry weight p e r c e n t P of the sl u d g e would have t o be 3.0%. However, f o r a p r o c e s s t o e x h i b i t the same degree of system P removal p e r day p e r u n i t mass of sl u d g e a t a 25 day sludge age, the d r y weight p e r c e n t P c o n t e n t of the sludge would have t o be 5.0%. I t can thus be seen t h a t , f o r a g i v e n s e t of o p e r a t i n g c o n d i t i o n s , the a b i l i t y of a p r o c e s s t o remove P from the wastewater i s l i m i t e d by the maximum a t t a i n a b l e P c o n t e n t of the s l u d g e . I n g e n e r a l , r e d u c i n g the sl u d g e age of a p r o c e s s w i l l have the f o l l o w i n g e f f e c t s : 1) The mass of sludge i n the p r o c e s s and, t h e r e f o r e , the MLSS c o n c e n t r a t i o n w i l l d e c r e a s e . However, the a c t i v e s l u d g e f r a c t i o n w i l l i n c r e a s e ( M a r a i s and Ekama, 19 76). 2) The r e q u i r e d P c o n t e n t of the s l u d g e f o r a g i v e n system P removal w i l l be reduced. For these reasons, i t i s recommended t h a t the sl u d g e age of a p r o c e s s d e s i g n e d f o r e x c e s s b i o l o g i c a l P removal be kept as low as p o s s i b l e , i n o r d e r t o enhance the P removal c h a r a c t e r i s t i c s of the p r o c e s s . The lower l i m i t c o u l d be d e t e r m i n e d by the s e t t l i n g , d e w a t e r i n g and h a n d l i n g c h a r a c t e r i s t i c s of the sludge (problems i n sludge h a n d l i n g a r e o f t e n a t t r i b u t e d t o a h i g h a c t i v e s l u d g e f r a c t i o n ) , and the n i t r i f y i n g c h a r a c t e r i s t i c s of -143-the process, taking into account the lower growth rate of the n i t r i f i e r s and the negative e f f e c t of the unaerated sludge mass fract ion. -144-CHAPTER NINE CONCLUSIONS AND RECOMMENDATIONS Sign i f i c a n t progress has been made i n b i o l o g i c a l P removal technology during the course of th i s study. The research reported in this thesis has contributed towards a greater understanding of the P removal mechanism and how i t may be applied in the design of the nutrient removal activated sludge process. The conclusions of th i s research may be summarized as follows: 1) Anaerobic batch tests, using sludge from plants exhibiting excess b i o l o g i c a l P removal, have revealed that d i f f e r e n t soluble carbonaceous substrates exhibit a range of effectiveness in inducing anaerobic P release when COD i s used as the control parameter. The effectiveness in inducing anaerobic P release appears to be a function of the complexity of the substrate used with the simpler substrates, sodium acetate and propionic acid, being the most effe c t i v e and the more complex substrates, such as glucose and butyric acid, being s i g n i f i c a n t l y l e s s e f f e c t i v e . 2) The results of an anaerobic batch test using d e n i t r i f i e d activated sludge and a range of i n i t i a l sodium acetate concentrations between 0 and 100 mg/L (as COD) c l e a r l y show that P release took place in two d i s t i n c t phases. I n i t a l l y , there was a rapid release phase i n which the release rate appeared to be independent of the i n i t i a l substrate concentration but i n which the mass of P released i s a function of the mass of substrate -145-available. This was followed by a s i g n i f i c a n t l y lower release rate which continued for the duration of the anaerobic phase. Furthermore, there appears to be an upper l i m i t to the mass of P that a given sludge can release, beyond which additional substrate w i l l not cause any additional release. This upper P release l i m i t appears to be some function of the mass of i n t r a c e l l u l a r l y stored poly-P that i s available for release under suitable anaerobic conditions, and the MLSS concentration of the sludge used in the batch test. 3) The results of batch tests in which the disappearance of acetate from the supernatant was monitored during the P release phase cl e a r l y indicate that anaerobic P release and substrate u t i l i z a t i o n are integral parts of the same mechanism. There appears to be some form of a di r e c t exchange phenomenon occurring between the two molecules at a molar exchange r a t i o of 1.76 moles of P released per mole of acetate u t i l i z e d . (On the basis of mass, this exchange ra t i o i s eguivalent to 0.91 mg P per mg of acetate (as HAc)). This observation supports the proposed biochemical kinetic model for the excess b i o l o g i c a l P removal mechanism of Comeau ( 1985b). In this model, the function of P release i s to f a c i l i t a t e the transport of acetate across the c e l l wall by maintaining the proton motive force of the c e l l . The carbonaceous substrate that i s taken up by the c e l l s under anaerobic conditions i s stored as poly-B-hydroxybutyrate (PHB). 4) In monitoring the ORP of anaerobic batch tests, i t was not possible to define the prereguisite conditions for anaerobic P -146-release in terms of the mixed liquor ORP. In a l l cases where ORP was monitored, P release commenced immediately upon substrate addition and some time before a minimum l e v e l of ORP was established in the experimental flasks. This may, however, largely be a function of the probe response time and be peculiar to batch testing conditions. With regard to the eff e c t of nitrate on the ORP lev e l i n anaerobic flasks, the disappearance of n i t r a t e i s marked by a s i g n i f i c a n t increase in the rate of change of ORP, resulting in a "bend" i n the ORP vs time curve. These two aspects of the bi o l o g i c a l P removal research program carried out at UBC, together with the potential of ORP as a monitoring and control parameter i n continuous flow nutrient processes, are dealt with by Koch and Oldham ( 1984). 5) In batch tests designed to quantify the negative effect of nit r a t e on the anaerobic P release mechanism, i t was shown that the e f f e c t was not as great as that predicted by S i e b r i t z et al . ( 1982, 1983), i . e . that any available substrate i s u t i l i z e d p r e f e r e n t i a l l y in the d e n i t r i f i c a t i o n reaction at a rate of 8.6 mg COD/mg NO3-N and i s thus rendered unavailable for the P release mechanism. In batch tests where excess substrate was available to the organisms, the presence of up to 9 mg/L of ni t r a t e (as N) had no detrimental effect on P release. However, in a subsequent batch test in which the a v a i l a b i l i t y of substrate was more limited, the available substrate appeared to be u t i l i z e d p r e f e r e n t i a l l y in the d e n i t r i f ication reaction at a rate of 3.6 mg COD/mg NO3-N, calculated on the basis of the detrimental e f f e c t of ni t r a t e on the P release mechanism. -147-6) In experiments where a sodium acetate solution was added to the unaerated zone of the p i l o t - s c a l e activated sludge process, the P removal c h a r a c t e r i s t i c s , as measured by the AP/ACOD r a t i o of the process and the dry weight percent P content of the sludge, showed s i g n i f i c a n t improvement. For example, the addition of 86 mg/L of acetate (measured as mg of COD per l i t r e of influent) to the influent end of a s i m p l i f i e d nutrient removal process improved the AP/ACOD r a t i o from 0 .0069 to 0.0102 and increased the dry weight percent P content of the sludge from 1.46% to 2.34%. Furthermore, when acetate was added to an unaerated zone that received no incoming n i t r a t e concentration, s i g n i f i c a n t l y greater e f f i c i e n c y of the added substrate was made by the organisms of the process for the excess b i o l o g i c a l P removal mechanism. The addition of 39 mg COD/L of acetate to such a zone resulted in a AP/ACOD of 0.0142 and a dry weight percent P content of the sludge of 2.54%. 7) Operation of the p i l o t - s c a l e primary sludge fermenter demonstrated that the two most effe c t i v e substrates in inducing anaerobic P release in activated sludge, acetate and propionate, are also the p r i n c i p l e products of primary sludge fermentation, making up more than 95% of the t o t a l short-chain VFA production. The acetate:propionate production r a t i o was found to be approximately 55:45 and t h i s r a t i o appears to independent of sludge age, at least for sludge ages between 2.1 and 10 days. The best y i e l d of t o t a l VFA produced by primary sludge fermentation was found to be approximately 0.09 mg VFA (as HAc) per mg of primary sludge (as COD). This optimum y i e l d was -148-achieved at fermenter sludge ages of between 3.5 and 5.0 days with s l i g h t l y lower yields being attained at both shorter and longer sludge ages. However, i t may be possible to p a r t i a l l y explain the lower VFA yields in terms of the lower fermenter operating temperatures and MLSS concentrations during some experimental periods. Decreasing the mean fermenter temperature from about 19°C to about 13°C resulted in a drop in VFA production of approximately 2 0%, a value s i g n i f i c a n t l y less than that predicted by the general theory of microbial a c t i v i t y . Increasing the mean fermenter pH from about 5.7 to near neutrality by the addition of sodium hydroxide did not result i n an improvement in VFA production. However, these experiments need to be repeated under conditions that are more stringently controlled. 8) V o l a t i l e fatty acids can be produced by primary sludge fermentation on-site at an activated sludge treatment plant in s u f f i c i e n t quantities to s i g n i f i c a n t l y improve the P removal chara c t e r i s t i c s of the process. The incorporation of primary sludge fermentation into the design of the nutrient removal process shows great potential for both future plants and the r e t r o f i t t i n g of existing plants. For the two p i l o t - s c a l e activated sludge process configurations used i n this research, the incorporation of primary sludge fermentation into the process design s i g n i f i c a n t l y improved the P removal c h a r a c t e r i s t i c s of both processes. For example, the incorporation of primary sludge fermentation into a si m p l i f i e d nutrient removal process improved the AP/ACOD of the process from 0 .0069 to 0.0141 and the dry - 1 4 9 -w e i g h t p e r c e n t P c o n t e n t o f t h e s l u d g e f r o m 1 . 4 6% t o 3 . 2 0 % . I n c o r p o r a t i o n o f p r i m a r y s l u d g e f e r m e n t a t i o n i n t o t h e UCT p r o c e s s i m p r o v e d t h e AP/ACOD r a t i o f r o m 0 . 0 0 8 6 t o 0 . 0 1 3 6 a n d t h e d r y w e i g h t p e r c e n t P c o n t e n t o f t h e s l u d g e f r o m 2 . 1 1 % t o 3 . 1 0 % . F u r t h e r r e s e a r c h w o r k i s r e c o m m e n d e d i n t h e f o l l o w i n g a r e a s : 1 ) A p i l o t - s c a l e s t u d y o f t h e p r o p o s e d m e t h o d o f p r i m a r y s l u d g e f e r m e n t e r o p e r a t i o n , w i t h i n d e p e n d e n t SRT a n d HRT a n d n o f e r m e n t e r s e c o n d a r y c l a r i f i e r , a s o u t l i n e d i n C h a p t e r E i g h t ( S e c t i o n 8 . 6 ) . 2 ) A c o m p r e h e n s i v e p i l o t - s c a l e s t u d y o f t h e k i n e t i c s o f p r i m a r y s l u d g e f e r m e n t a t i o n , w i t h p a r t i c u l a r r e f e r e n c e t o t h e e f f e c t s o f , a n d t h e a c c u r a t e c o n t r o l o f t h e s l u d g e a g e , t e m p e r a t u r e , p H a n d MLSS c o n c e n t r a t i o n . 3 ) An e c o n o m i c e v a l u a t i o n o f t h e e n c h a n c e m e n t o f t h e P r e m o v a l c h a r a c t e r i s t i c s o f t h e a c t i v a t e d s l u d g e p r o c e s s b y p r i m a r y s l u d g e f e r m e n t a t i o n , w i t h p a r t i c u l a r r e f e r e n c e t o o p e r a t i o n o f t h e f e r m e n t e r i n t h e m e s o p h i l i c t e m p e r a t u r e r a n g e . 4 ) A s e r i e s a b a t c h t e s t i n g , u s i n g s u c h t e c h n i q u e s s u c h a s r a d i o a c t i v e i s o t o p e l a b e l i n g a n d PHB e x t r a c t i o n , d e s i g n e d t o a c c u r a t e l y d e t e r m i n e t h e f a t e o f t h e s u b s t r a t e i n t h e e x c e s s b i o l o g i c a l P r e m o v a l m e c h a n i s m a n d i n t h e d e n i t r i f i c a t i o n r e a c t i o n . -150-B I B L I O G R A P H Y A l a r c o n G.O. 19 61. Removal of p h o s p h o r u s from sewage. M a s t e r s e s s a y , John H o p k i n s U n i v . , B a l t i m o r e , Md. Andrews J . F . and E.A. P e a r s o n 19 65. K i n e t i c s and c h a r a c t e r i s t i c s o f v o l a t i l e a c i d p r o d u c t i o n i n a n a e r o b i c f e r m e n t a t i o n p r o c e s s e s . I n t . J o u r . A i r Water P o l l u t . , 9 , 4 39-461 . A r v i n E. 1985. B i o l o g i c a l r e m o v a l of p h o s p h o r u s from w a s t e w a t e r . CRC C r i t i c a l Rev. E n v i r . C o n t r o l , 15 , 25-64 . Bargman R.D., J.M. B e t z and W.F. G a r b e r 19 70. C o n t i n u i n g s t u d i e s i n the r e m o v a l o f p h o s p h o r u s by t h e a c t i v a t e d s l u d g e p r o c e s s . Chem. Eng. Symp. S e r i e s , 67, 117-121. B a r n a r d J . L . 19 74. C u t P a n d N w i t h o u t c h e m i c a l s . Water and Wastes E n g i n e e r i n g , 11, 33-36. B a r n a r d J . L . 1975. B i o l o g i c a l n u t r i e n t r e m o v a l w i t h o u t t h e a d d i t i o n o f c h e m i c a l s . Water R e s e a r c h , 9 , 485-490. B a r n a r d J . L . 19 75. N u t r i e n t r e m o v a l i n b i o l o g i c a l s y s t e m s . Water P o l l u t i o n C o n t r o l , 74, 2, 143-154. B a r n a r d J . L . 1976. A r e v i e w of b i o l o g i c a l p h o s p h o r u s r e m o v a l i n t h e a c t i v a t e d s l u d g e p r o c e s s . Water S.A., 2, 3, 136-144. B a r n a r d J . L . 19 84 . A c t i v a t e d p r i m a r y t a n k s f o r p h o s p h a t e r e m o v a l . Water S.A., 10, 3, 121-126. B a r n a r d J . L . 1985. The r o l e of f u l l s c a l e r e s e a r c h i n b i o l o g i c a l p h o s p h a t e r e m o v a l . P r o c . I n t e r . C o n f . on New D i r e c . and Res. i n Waste T r e a t , and R e s i d . Manag., V a n c o u v e r , B.C., J u n e , 1985. B o r c h a r d t J.A. 19 70. A n a e r o b i c phase s e p a r a t i o n by d i a l y s i s t e c h n i q u e . I n A n a e r o b i c B i o l o g i c a l T r e a t m e n t P r o c e s s e s . E d . F.G. P o h l a n d . Amer. Chem. S o c . Wash., D.C. Chang J.P. and J . E . M o r r i s 19 62 . S t u d i e s of t h e u t i l i z a t i o n o f n i t r a t e by M i a o c o c c u s D e n i t r i f i c a n s . J o u r . Gen. M i c r o b i a l . , 29, 3 01. Chynoweth D.P. and R.A. Mah 19 70. V o l a t i l e a c i d f o r m a t i o n i n s l u d g e d i g e s t i o n . I n A n a e r o b i c B i o l o g i c a l T r e a t m e n t P r o c e s s e s . E d . F.G. P o h l a n d . Amer. Chem. S o c . Wash., D.C. Comeau Y., K . J . H a l l , R.E.W. Hancock and W.K. Oldham 19 85a. B i o c h e m i c a l model f o r e n h a n c e d b i o l o g i c a l p h o s p h o r u s . P r o c . I n t e r . C o n f . on New D i r e c . and Res. i n Waste T r e a t , and R e s i d . Manag., V a n c o u v e r , B.C., J u n e , 1985. -151-Comeau Y. , B. R a b i n o w i t z , K . J . H a l l and W.K. Oldham 19 85b. P h o s p h o r u s r e l e a s e a n d u p t a k e i n e n h a n c e d b i o l o g i c a l p h o s p h o r u s r e m o v a l from w a s t e w a t e r . A c c e p t e d f o r p r e s e n t a t i o n a t t h e 8 t h Annu. Symp. on Wastewater T r e a t . , M o n t r e a l , Que., November, 19 85. D o l d P.L., G.A. Ekama and G.v.R. M a r a i s 19 82 . A g e n e r a l model f o r the a c t i v a t e d s l u d g e p r o c e s s . P r o g . Water T e c h . , 12, 47-77. Ekama G.A., G.v.R. M a r a i s and I.P. S i e b r i t z 19 84 . B i o l o g i c a l e x c e s s p h o s p h o r u s r e m o v a l . C h a p t e r 7. T h e o r y , d e s i g n a n d o p e r a t i o n of n u t r i e n t r e m o v a l a c t i v a t e d s l u d g e p r o c e s s e s . Water R e s e a r c h Commission, P.O. Box 824, P r e t o r i a 0001. Feng T.H. 19 62 . P h o s p h o r u s and the a c t i v a t e d s l u d g e p r o c e s s . Water a n d Sewage Works, Nov., 43 1-434 . F l o r e n t z M. and P. G r a n g e r 19 82. P h o s p h o r u s 3 1 n u c l e a r m a g n e t i c r e s o n a n c e of a c t i v a t e d s l u d g e u s e f o r t h e s t u d y o f t h e b i o l o g i c a l r e m o v a l of p h o s p h a t e s from w a s t e w a t e r . S u b m i t t e d f o r p u b l i c a t i o n t o B i o c h e m . a n d B i o p h y s . R e s e a r c h C o m m u n i c a t i o n s . Fuhs G.W. and M. Chen 19 75 . M i c r o b i o l o g i c a l b a s i s of p h o s p h a t e r e m o v a l i n t h e a c t i v a t e d s l u d g e p r o c e s s f o r t h e t r e a t m e n t o f w a s t e w a t e r . M i c r o b i a l E c o l o g y , 2, 119-138. Fuk a s e T. , M. S h i b a t a and Y. M i j a j i 19 82 . S t u d i e s on t h e mechanism of b i o l o g i c a l p h o s p h o r u s r e m o v a l 19 82. T r a n s . J . Mardon. J a p a n J o u r . Water P o l l u t . R e s e a r c h , 5, 6, 309-317. Ghosh S. , J.R. C o n r a d and D.L. K l a s s 19 75. K i n e t i c s of s u b s t r a t e a s s i m i l a t i o n and p r o d u c t f o r m a t i o n i n a n a e r o b i c d i g e s t i o n . J o u r . Water P o l l u t . C o n t r o l F e d . , 46, 748. G u p t a A.K., W.K. Oldham and P.F. Coleman 19 85. The e f f e c t s of t e m p e r a t u r e , pH a n d r e t e n t i o n t i m e on v o l a t i l e f a t t y a c i d p r o d u c t i o n from p r i m a r y s l u d g e . P r o c . I n t e r . C o n f . on New D i r e c . and Res. i n Waste T r e a t , a n d R e s i d . Manag., V a n c o u v e r , B.C., J u n e , 19 85. H a l l E . , H.A. N i c h o l l s and D.W. O s b o r n 1978. P r o g r e s s i n J o h a n n e s b u r g towards t h e b i o l o g i c a l r e m o v a l o f p h o s p h o r u s from sewage e f f l u e n t s . P r e s e n t e d a t 1 1 t h E s s e n C o n f e r e n c e , March, 1978. H a r o l d F.M. 1966. I n o r g a n i c p o l y p h o s p h a t e s i n b i o l o g y : S t r u c t u r e , m e t a b o l i s m and f u n c t i o n . Amer. S o c . f o r M i c r o b i o l o g y - B a c t e r i o l o g i c a l R e v i e w s , 30, 772-794. Hoffmann R. and G.v.R. M a r a i s 19 77. P h o s p h o r u s r e m o v a l i n t h e m o d i f i e d a c t i v a t e d s l u d g e p r o c e s s . R e s e a r c h R e p o r t W 22, D e p t . of C i v . Eng., U n i v e r s i t y of Cape Town. -152-J e r i s J.S. and P.L. McCarty 1965. The b i o c h e m i s t r y of methane f e r m e n t a t i o n u s i n g 14C t r a c e r s . J o u r . Water P o l l u t . Con. Fed. , 37, 178-192. Koch F.A. and W.K. Oldham 19 84 . ORP - A t o o l f o r m o n i t o r i n g , c o n t r o l and o p t i m i z a t i o n of b i o l o g i c a l n u t r i e n t removal systems. P r e s . a t the 12th Conf of the IAWPRC, P o s t - C o n f . Seminar on Enhanced B i o l . Phosphorus Removal from Wastewater, P a r i s , September, 1984 . L e v i n G.V. and J . S h a p i r o 1965. M e t a b o l i c uptake of phosphorus by wastewater organisms. J o u r . Water P o l l u t . C o n t r o l Fed., 37, 6, 800-821. Manoharan R. 1985. P e r s o n a l Communication. M a r a i s G.v.R. and G.A. Ekama 1976. The a c t i v a t e d sludge p r o c e s s p a r t 1 - Steady s t a t e b e h a v i o u r , Water S.A. , 2 , 4 , 163-200. McCarty P.L., L. Beck and P. S t . Amant 19 69. B i o l o g i c a l d e n i t r i f i c a t i o n of wastewaters by a d d i t i o n of o r g a n i c m a t e r i a l s . P r o c e e d i n g s 2 4 t h I n d u s t r i a l Waste C o n f e r e n c e , Purdue U n i v . , West L a y f a y e t t e , I n d i a n a . McCarty P.L., J.S. J e r i s and W. Murdoch 19 63. The s i g n i f i c a n c e of i n d i v i d u a l v o l a t i l e a c i d s i n a n a e r o b i c t r e a t m e n t . J o u r . Water P o l l u t . C o n t o l Fed., 35, 421-439. McLaren A.R. and R.J. Wood 19 76. E f f e c t i v e phosphorus removal from sewage by b i o l o g i c a l means. Water S.A. , 2 , 1 , 47-50. M e t c a l f and Eddy, I n c . 1979. Wastewater E n g i n e e r i n g : Treatment, D i s p o s a l , Reuse. 2nd Ed. M c G r a w - H i l l . B o s t o n , MA. M i l b u r y W.F., M.N. B h a t l a and V.T. Stack 1970. E f f e c t of d i s s o l v e d oxygen on phosphorus removal i n m u n i c i p a l a c t i v a t e d s l u d ge t r e a t m e n t . Chem. Eng. P r o g . Symp. S e r i e s , 107, 61, 100-106. M i l b u r y W.F., D. McCauley and C H . Hawthorne 19 71. O p e r a t i o n of c o n v e n t i o n a l a c t i v a t e d sludge f o r maximum phosphorus removal. J o u r . Water P o l l u t . C o n t r o l Fed., 43, 9, 1890-1901. N i c h o l l s H.A. 1978. K i n e t i c s of phosphorus t r a n s f o r m a t i o n s i n a e r o b i c and a n a e r o b i c e n v i r o n m e n t s . P r e s e n t e d a t t h e 9th IAWPR Po s t - C o n f . Seminar, Copenhagen, June. P r o g . Water Tech. , 10. N i c h o l l s H.A. and D.W. Osborn 1979. B a c t e r i a l s t r e s s : a p r e r e g u i s i t e f o r b i o l o g i c a l removal of phosphorus. J o u r . Water P o l l u t . C o n t r o l Fed., 51, 3, 557-569. -15 3-N i c h o l l s H.A. 1982. A p p l i c a t i o n o f t h e Marais-Ekama a c t i v a t e d s l u d g e model t o l a r g e p l a n t s . Water S c i . T e c h . , 14, 581-598. N i c h o l l s H.A., A.R. P i t m a n and D.W. O s b o r n 19 84. The r e a d i l y b i o d e g r a d a b l e f r a c t i o n o f sewage: I t s i n f l u e n c e on p h o s p h o r u s r e m o v a l and measurement. P r o c . 1 2 t h C o n f . o f the IAWPRC, P o s t - C o n f . S e m i n a r on E n h a n c e d B i o l . P h o s p h o r u s Removal from Wastewater, P a r i s , September, 19 84. Oldham W.K. 1984 . F u l l - s c a l e o p t i m i z a t i o n o f b i o l o g i c a l p h o s p h o r u s r e m o v a l a t Kelowna. P r o c . 1 2 t h C o n f . o f t h e IAWPRC, P o s t - C o n f . S e m i n a r on Enhanced B i o l . P h o s p h o r u s Removal from Wastewater, P a r i s , September, 1984. R a b i n o w i t z B. and G.v.R. M a r a i s 1980. C h e m i c a l and b i o l o g i c a l p h o s p h o r u s r e m o v a l i n t h e a c t i v a t e d s l u d g e p r o c e s s . R e s e a r c h R e p o r t W 32, De p t . o f C i v . E ng., U n i v e r s i t y o f Cape Town. R a b i n o w i t z B. and W.K. Oldham 1985. E x c e s s b i o l o g i c a l p h o s p h o r u s r e m o v a l i n the a c t i v a t e d s l u d g e p r o c e s s u s i n g p r i m a r y s l u d g e f e r m e n t a t i o n . P r e s e n t e d a t t h e C.S.C.E. A n n u a l C o n f e r e n c e , S a s k a t o o n , May, 1985. R a b i n o w i t z B. and W.K. Oldham 19 85. The use o f p r i m a r y s l u d g e f e r m e n t a t i o n i n t h e e n h a n c e d b i o l o g i c a l p h o s p h o r u s r e m o v a l p r o c e s s . P r o c . I n t e r . C o n f . on New D i r e c . i n Waste T r e a t , and R e s i d . Manag., V a n c o u v e r , B.C., J u n e , 1985. R a n d a l l C.W., D.W. M a r s h a l l and P.H. K i n g 1970. P h o s p h a t e r e l e a s e i n a c t i v a t e d s l u d g e p r o c e s s . J o u r . S a n . E n g . D i v . , ASCE, 96, SA2 , 395-408. R e n s i n k J.H. 1981. B i o l o g i s c h e de f o s f a t e r i n g e n p r o c e s s b e p a l e n d e f a k t o r e n . I n Symp. Book - D e f o s f a t e r i n g niewe o n t w i k k e l i n g e n p r a k t i j k e r v a r i n g e n i n N e d e r l a n d and Sweden. NVA Synp. ( I n D u t c h ) . R e n s i n k J.H., H.J.G.W. Donker and H.P. de V r i e s 19 81. B i o l o g i c a l P r e m o v a l i n d o m e s t i c w a s t e w a t e r by a c t i v a t e d s l u d g e . P r e s e n t e d a t the 5 t h E u r o . Sew. and R e f u s e Symp., Mun i c h , J u n e , 1981. S c a l f M.R., F.M. P f e f f e r , L.D. L i v e l y , J.O. Witherow and C.P. P r i e s i n g 1969. P h o s p h a t e r e m o v a l i n B a l t i m o r e , M a r y l a n d . J o u r . San. Eng. D i v . ASCE, 95, SA5, 817-827. S h a p i r o J . , G.V. L e v i n and H. Zea 19 67. A n o x i c a l l y i n d u c e d r e l e a s e o f p h o s p h a t e i n w a s t e w a t e r t r e a t m e n t . J o u r . Water P o l l u t . C o n t r o l F e d . , 39, 11, 1811-1818. -154-S i e b r i t z I . , G.A. Ekama and G.v.R. M a r a i s 19 80. Excess b i o l o g i c a l phosphorus removal i n the a c t i v a t e d s l u d g e p r o c e s s a t warm temperate c l i m a t e s . P r o c . Waste Treatment and U t i l i z a t i o n , V o l . 2, 233-251, Eds. C.W. Robinson, M. Moo-Young and G.J. F a r q u a r , Pergamon P r e s s , T o r o n t o . S i e b r i t z I . , G.A. Ekama and G.v.R. M a r a i s 19 82 . A p a r a m e t r i c model f o r b i o l o g i c a l e x c e s s phosphorus r e m o v a l . P r e s e n t e d a t the I.A.W.P.R. p o s t - c o n f e r e n c e seminar on phosphate r e m o v a l , P r e t o r i a , A p r i l , 1982. S i e b r i t z I . , G.A. Ekama and G.v.R. M a r a i s 19 83 . B i o l o g i c a l e x c e s s phosphorus removal i n the a c t i v a t e d sludge p r o c e s s . Research Report W 47, Dept. of C i v . Eng., U n i v e r s i t y of Cape Town. Simpkins M.J. and A.R. McLaren 19 78. C o n s i s t e n t b i o l o g i c a l phosphate and n i t r a t e removal i n an a c t i v a t e d s l u d g e p l a n t . P r o g . Water Tech., 10, 5/6, 433-442. S r i n a t h E.G., C A . S a s t r y and S.C,. P i l l a i 1959. Rapid removal of phosphorus from sewage by a c t i v a t e d s l u d g e . Water and Waste Treatment, 11, 410. St a n d a r d Methods f o r the E x a m i n a t i o n of Water and Wastewater 1980 . 15th Ed. Americ. Pub. H e a l t h Assoc. Wash., D.C. Sup e l c o 1982 . S e p a r a t i n g aqueous f r e e c a r b o x y l i c a c i d s (C2-C5) a t ppm c o n c e n t r a t i o n s . S u p e l c o I n c . B u l l . 751E. B e l l a f o n t e , Pa. Tec h n i c o n 19 73a. Orthophosphate i n water and wastewater (range: 0-10 mg/L). Tec h n i c o n I n d . Systems. I n d . Method 94-70W. Ta r r y t o w n , N.Y. Te c h n i c o n 1973b. N i t r a t e and n i t r i t e i n water and wastewater (range: 0-2 mg/L). Tec h n i c o n I n d . Systems. I n d . Method 100-70W. T a r r y t o w n , N.Y. Te c h n i c o n 19 74. O p e r a t i o n manual f o r the T e c h n i c o n b l o c k d i g e s t e r , Models BD-20 and BD-40. Tech. Pub. No. 4-0323-00. T a r r y t o w n , N.Y. Vac k e r D. , C H . C o n n e l l and W.N. W e l l s 19 67. Phosphate removal through m u n i c i p l e wastewater t r e a t m e n t a t San A n t o n i o , Texas. J o u r . Water P o l l u t . C o n t r o l Fed., 39, 5, 750-771. van Haandel A . C , G.A. Ekama and G.v.R. M a r a i s 19 81. The a c t i v a t e d s l u d g e p r o c e s s p a r t 3 - S i n g l e sludge d e n i t r i f i c a t i o n . Water R e s e a r c h , 15, 1135-1152. van Haandel A.C and G.v.R. M a r a i s 19 81. N i t r i f i c a t i o n and d e n i t r i f i c a t i o n i n the a c t i v a t e d s l u d g e p r o c e s s . Research Report W 39, Dept. of C i v . Eng., U n i v e r s i t y of Cape Town. -155-Wells W.N. 1969. D i f f e r e n c e s i n phosphate uptake r a t e s e x h i b i t e d by a c t i v a t e d sludges. J o u r . Water P o l l u t . C o n t r o l Fed., 41, 5, 765-771. Wentzell M.C., P.L. Dold, G.A. Ekama and G.v.R. Marais 19 84 . K i n e t i c s of b i o l o g i c a l phosphorus r e l e a s e . Proc. 12th Conf. of the IAWPRC, Post-Conf. Seminar on Enhanced B i o l . Phosphorus Removal from Wastewater, P a r i s , September. Y a l l I ., W.H. Boughton, R.C. Knudsen and N.A. S i n c l a i r 19 70. B i o l o g i c a l uptake of phosphorus by a c t i v a t e d sludge. A p p l i e d M i c r o b i o l o g y , 20, 1, 145-150. APPENDIX A l RAW DATA FROM CHAPTER F I V E P I L O T - S C A L E SUBSTRATE ADDITION -157-COD, T o t a l P and TKN Raw D a t a from S e c t i o n 5.1.1 Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mq/L) (mq/L) (mq/L) (mq/L) (mg/L) (mq/L) (mq/L) 1 2 3 - -3.54 2.12 - - -4 - - 3.48 2.12 - - -5 183 - 3.33 2.30 21.6 - -6 214 - 3 .32 2.32 19 .4 - 2950 7 206 - - - 19.8 - -8 25 3 - - - 20.2 - -9 409 - 4.93 2.84 23.7 - 29 0 0 10 152 - 4.63 2.87 21.6 - 2850 11 362 - 4.59 2.68 21.9 - 2880 12 206 - 3 .44 2.70 21.9 - 2870 13 310 - 4.37 2.80 18 .7 - 273 0 14 302 - - - 23 .4 - -15 226 - - - 20.5 - -16 282 - 4 .35 3.12 23.8 - 2500 17 190 - 4.20 2.90 16 .8 - 2580 Mean 253 - 4 .02 2.62 21 .02 - 2783 COD, T o t a l P and TKN Raw D a t a from S e c t i o n 5.1.2 Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mq/L) (mq/L) (mq/L) (mg/L) (mg/L) (mg/L) (mg/L) , 1 250 - 3.52 2.60 20.7 - 2575 2 218 - 2.94 2.02 18.9 - 2975 3 306 - - 1.85 18 .3 - 3200 4 c, — — — — 20.0 - -6 204 67 3.30 2.20 20.0 1.8 2560 7 222 - 3.50 2.60 19 .3 - 29 60 8 214 - 3 .70 1.90 19 .4 - 3140 9 190 69 3.60 1.80 20.0 4.0 -10 169 - 3 .40 2.10 - — — 11 1 0 - - - - - - -1 z 13 314 79 4.50 2.40 23.4 <1.0 2220 14 - - 4 .60 2 .40 - - -15 259 - 4.00 2.50 - - 283 0 16 371 71 5.50 2 .40 28 .6 2.6 2660 Mean 247 71 3.87 2.23 20.86 2.23 2791 COD, T o t a l P and TKN Raw D a t a from S e c t i o n . 5.1.3 Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 1 320 42 4.70 <0.10 25.5 1.4 3474 2 173 - 3.00 <0.10 15.5 0.7 3284 3 121 - 2.40 <0.10 15.2 1.4 3188 - 1 5 8 -COD, T o t a l P and TKN Raw Data . f rom S e c t i o n 5. 1.3 ( c o n t . ) )ay # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mq/L) (ma/L) 4 175 . 44 2.60 <0.10 16 .7 1.4 2998 5 184 - 2.40 <0.10 15.5 1.5 3000 6 200 - 2.60 <0.10 20.6 1.4 — 7 223 - 3.20 <0.10 22 .5 1.3 — 8 247 51 3.60 <0.10 22 .0 1.2 3028 9 257 - 3 .40 <0.10 20 .8 1.2 2895 10 273 - 3.40 <0.10 20.6 1.1 3 059 11 206 55 2.90 <0.10 18.9 1.0 -12 221 - 3.40 <0.10 2 0 . 1 1.2 -13 220 - 2.90 <0.10 19 .7 1.5 — 14 159 - 2.90 <0.10 22.6 1.2 -15 347 92 3 .60 <0.10 19.8 1.3 3013 16 214 - 3.00 <0.10 19 . 1 1.4 3037 17 269 - 3 .00 <0.20 18.9 1.1 29 6 8 18 221 73 2.80 <0.20 18 .5 0.8 2919 19 167 - 2.50 <0.20 17.2 1.2 2988 20 202 - 2.70 <0.20 18 .4 0.9 -21 206 - 3 .30 <0.20 20 .2 1.0 -22 255 60 4.30 <0.20 24.6 1.1 2829 23 25 3 - 3 .80 0.20 22 .9 1.5 2837 24 266 - • 3.10 0.20 20 .3 1.2 2925 25 268 55 3 .70 0.20 21 .8 1.8 2939 26 19 8 - 3.50 0 .40 23.3 1.2 2839 27 268 - 3 .60 <0.20 21 .7 0.9 — 28 255 - 3.30 0 .30 19 .9 1.1 -29 237 48 3 .40 <0.20 20 .2 1.2 2705 30 200 - 3.30 0.20 19.2 0.8 2803 31 176 - 2.80 <0.20 20 .8 1.2 — 32 281 40 3.30 - 23 .9 - 2775 33 192 - 3 .30 0.40 26 .2 1.2 2691 34 212 - 3.60 0 .50 20 .8 1.0 — 35 225 - 3 .60 0.70 21 .3 1.0 -36 194 40 3.40 0 .70 20 .4 1.1 2582 37 185 - 3 .00 0.90 20 .4 1.1 2592 38 161 - 2.60 0 .50 20 .7 1.5 -39 189 56 3.20 0.70 22 .2 1.6 -40 182 - 3.50 1.30 23 .0 1.4 2524 41 194 - 3.90 1.80 24 .3 1.5 -42 220 - 4.20 1.90 22 .7 1.5 -43 225 53 3.80 1.90 2 3 . 2 1.5 2482 44 222 - 3.70 2 .30 22.6 1.5 2413 45 227 - 3.20 2.20 20 .7 1.7 2448 46 220 53 3.10 2 .00 20 .0 1.6 2375 47 207 - . 2.90 1.90 20 .3 1.8 2296 48 289 - 3.20 1.70 20 .8 2 .0 -49 261 - 3.50 1.90 2 2 . 8 2 . 1 -50 29 6 - 82 4.20 2 .40 25 .2 2 . 1 -51 29 6 - 4.10 2.20 25 .5 2.3 2314 52 244 - 3.80 2 .10 26 .7 2.6 2364 53 235 72 3 .30 1.60 2 5 . 8 2 .8 2187 - 1 5 9 -COD, T o t a l P and TKN Raw Data f rom Sect i o n 5 . 1.3 ( c o n t . ) Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mq/L) (mq/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 54 217 - 3.60 1.60 20.8 1.8 -55 215 - 3 .40 1.40 21 .3 2 .0 -56 227 - 2.10 1.30 21 .7 2 .4 — 57 245 82 3 .70 1.40 2 4 . 2 2 .7 — 58 239 - 3.40 1.20 24.6 2.8 2191 59 240 - 3.50 0 .80 22 .4 2 . 1 2164 60 218 - 3.40 0 .70 23 .2 1.6 2240 61 242 - 3 .80 0.70 26 .0 2.6 — Mean 226 59 3.32 0.73 21 .42 1.49 2732 COD, T o t a l P and TKN Raw Data f rom S e c t i o n 5 . 1 . 4 Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 1 204 - 2.90 0.83 18.4 4 .3 — 2 255 51 3 .80 0 .41 23 .8 3.6 2640 3 247 - 3.5 0 0.34 22 .4 2.5 283 0 4 204 51 3.20 0.30 19.2 <1.0 2410 5 231 - 3.40 0 .18 18 .7 2.0 2620 6 210 - 3.90 0.24 21 .4 1.0 — 7 - - - 0.20 - 1.2 — 8 182 21 2.90 0.70 15 .9 <1.0 2810 9 231 - 3.40 0 .85 18 .0 -<1.0 29 0 0 10 222 - 3.50 0.85 19 .3 <1.0 3100 11 191 51 2 .80 0 .70 18 .4 1.3 2950 12 207 - 2.70 0.62 21 .3 1.4 2910 13 168 - 3.00 0 .64 21.3 • 1.5 — 14 204 - 3 .10 0.84 19.8 1.8 — 15 235 28 4 .40 0.93 21.0 1.1 _ 16 217 - 3.50 0 .67 19.5 0.5 3000 17 181 - 2 .70 0.38 17 .7 0.8 3100 18 114 28 1.90 0.25 12 .8 1.2 3110 19 284 - 2 .70 0.23 20.5 1.0 — 20 165 - 2.40 0.23 17 .7 1.3 — 21 198 - 3.20 0 .30 18 .2 1.8 — 22 189 35 3 .30 0.20 11.3 1.3 3220 23 198 - 2.90 0 .30 18 .3 2.0 — 24 188 - 2.80 0 .10 19 .0 0 .7 3290 25 163 72 2 .60 0.10 16 .4 0.6 3300 26 181 - 3 .00 0.20 17.4 1.0 3200 27 170 - 2.90 0.10 16 .7 1.5 — 28 17 0 - 3 .40 0.10 19.9 0 .6 — 29 237 35 3.90 0.10 21 .5 0.8 3150 30 239 - 3.40 0.10 19.0 0 .8 3270 31 222 - 3.10 <0.10 19 .6 0.7 3080 32 181 31 2.30 - 17.4 - 3130 33 178 - 2.20 <0.10 15.5 0.5 3120 34 181 - 2.50 <0 .10 12 .6 0.7 — 35 229 - 3.10 <0.10 1 8 . 1 0 .7 — . - 1 6 0 -COD, T o t a l P and TKN Raw Data f rom S e c t i o n 5 . 1 . 4 Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 36 219 25 3.30 <0.05 17 .3 l 0 . 5 -37 175 - 3 .40 <0.10 17.9 0 .8 3210 38 210 - 2.90 <0.10 17 .9 0.6 3190 39 239 36 2.70 <0.05 24 .2 0 .7 3260 40 205 - 2.80 <0.05 21 .7 0 .7 — Mean 203 39 3.06 0.32 18 .64 1.12 3033 COD, T o t a l P and TKN Raw r Data f rom Sect i o n 5 .2 Day # I n f . COD E f f . COD I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) 1 309 - 4 .10 0.78 30.3 2.3 2660 2 333 - 3 .70 0.64 27 .8 1.2 2790 3 279 56 4 .40 0 .78 27 .7 1.3 2880 4 229 - 3 .40 0.62 21 .7 1.3 2540 5 245 - 4.00 - 27 .7 — — 6 276 - 4 .00 - 27.5 - -7 266 54 4.40 0.30 29 .6 0.9 2110 8 235 - 3.90 0.20 25 .4 <0.5 — 9 284 - 4.40 0.20 27 .8 0.8 2720 10 278 - 4.30 0.52 28 .3 0 .8 317 0 11 276 - - 0.14 - 0.7 -12 260 - 4.70 - 28.2 - -13 264 - 4.90 - 28 .8 - — 14 266 47 4.70 0 .30 28.9 1.3 2910 15 254 - 3.70 0.30 23 .8 1.3 28 80 16 223 - 2.97 0.27 23 .0 1.4 -17 207 - 2.56 0.66 19.3 1.0 2880 18 225 - 2.82 0.13 19 .0 1.4 2870 19 211 - 3.06 . - 19.8 - — 20 338 - 4.43 - 26 .8 - — • 21 264 49 3 .82 0.29 23.6 1.4 3060 22 281 - 4.50 <0 .20 24 .8 1.3 3040 23 215 - 4.00 <0.20 23 .5 0.9 3130 24 214 37 3 .40 0.20 22 .4 0.9 29 6 0 25 195 - 3.50 <0.20 21 .4 0.8 3040 26 216 - 3.50 <0.20 22 .3 1.0 -27 322 - 4.40 <0.20 26 .2 0.5 -28 216 39 3.90 <0.20 23 .7 0.5 2700 29 261 - 3.90 <0.20 25 .0 1.1 2512 30 234 - 3 .60 0 .40 22 .8 0 .8 2237 31 230 23 2.40 0.20 19.5 1.0 2100 32 203 - 2 .80 0 .40 21 .7 1.0 2140 33 335 - 4.00 - 25.8 1.1 — 34 266 - 4.30 - 2 4 . 1 1.4 -35 281 75 3.90 - 22.9 5.8 -36 349 - 5 .60 0 .60 3 1 . 2 4 .7 2627 37 298 - 4.00 0 .90 25.3 5.6 3814 38 252 45 4 .30 - 30.2 - 3900 - 1 6 1 -COD, T o t a l P and TKN Raw Data f rom S e c t i o n 5 .2 ( c o n t . ) Day # I n f . COD E f f . ( : O D I n f . P E f f . P I n f . TKN E f f . TKN MLSS (mg/L) (mg/L) (mg/L) (mq/L) (mq/L) (mq/L) (mq/L) 39 291 - 3.70 24.5 3.4 3528 40 244 - 4.10 - 24.9 - — 41 299 - 5.80 - 34.5 - — 42 272 - 4.80 0.20 28.5 0 .8 3857 43 256 - 4.30 <0.20 26 .2 0.8 3625 44 209 - 3 .70 0.24 26 .6 2 . 1 3710 45 179 - 3.30 0.12 22.3 0.8 3771 46 175 - 3.00 <0 .10 19 .8 1.0 3457 47 185 - 3.20 - 20.8 — — 48 229 - 3.90 - 23 .2 - -49 388 20 4 .00 <0.10 24.6 0 .7 3428 50 227 - 5 .40 <0 .10 23 .2 0 .7 3514 51 277 - 3 .90 <0.10 28.0 1.1 3628 52 324 - 4.50 0.50 30 .2 1.0 3635 53 340 39 4 .30 0.24 29 .7 1.9 — 5 4 293 - 5 .00 - 29 .8 — — 55 389 - 4.90 - 31.6 — — 56 347 - 4.20 0.28 27.3 - — 57 341 - 3.90 0.15 28.5 1.2 — 58 379 - 4.30 <0 .10 35.5 1.1 3900 59 291 - 4.30 <0 .10 40.3 1.0 4057 Mean 268 44 4 . 0 1 0.28 26 .00 1 .41 3105 O r t h o -P and N i t r a t e B i o r e a c t o r P r o f i l e s f rom S e c t i o n 5 . 1 . 1 O r t h o - P (mg/L) N0 3 + NOo (mg/L) 1s t 2nd 1s t 2nd Dav # Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 3 2 .12 2 .62 2 .21 2.23 0 . 95 0.13 10.20 10.30 4 2 .20 2 .20 2 .20 2 . 10 2 . 20 0.13 7.28 7 .60 6 2 .40 2 .64 2 .35 2 . 42 1 .60 0.13 7.68 7.68 9 3 .26 3 .57 2 .92 2 . 94 0 . 33 0.18 4 .56 4 .64 Mean 2 .50 2 .76 2 .42 2 .42 1 . 27 0.14 7.43 7.56 O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f rom S e c t i o n 5 . 1 . 2 1s t O r t h o - P 2nd (mg/L) NO3 + NO2 1s t 2nd (mg/L) Day # Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 2 2 .40 2.70 2 .40 2 .50 - - - — 4 2.40 2 .80 1.80 1.80 - - - — 7 2 .60 3 .20 2 .30 2.10 - - - — 9 2 .80 • 3 .80 1.80 1.70 <0.20 <0.20 4 . 7 0 2 .60 16 3 .42 4 .58 2.34 2.25 0 . 2 1 0.08 5.28 4 .84 Mean 2.72 3 .42 2.13 2.07 0.15 0.09 . 4 .99 3 .72 -162-O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f rom S e c t i o n 5 . 1 . 3 O r t h o - P (mg/L) NO3 + NO? (mg/L) 1 s t 2nd 1 s t 2nd Day # Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 1 6 .20 7.40 1.20 0.03 < 0 . 0 1 0 .05 3.10 3 .30 4 3.80 5.00 0 .03 0 .02 0 .02 0.03 4 .00 4 .00 8 3 .90 4 .60 0 .04 0 .06 0.12 0.10 2 .80 3 .10 11 4 .50 5 .40 0.06 0.05 0 .07 0.05 2 .70 2 .70 15 4 .10 5.10 0 .03 0 .04 0 . 0 1 0 . 0 1 3.90 3.80 18 5.10 5 .80 0.14 0.08 0 .05 0.07 3.40 3.40 22 3.90 5.70 0.30 0.08 0.10 0 .03 3.90 3 .90 25 3.07 4.17 0.24 0.10 0 .03 0 .02 3 .56 4 .27 30 6.00 7.70 0 .40 0 .20 0.10 0.05 2 .50 2.70 32 6.50 8.50 0.25 0.14 0 .09 0.04 4 .30 4 .60 36 7.20 9 .80 1.90 0 .52 0.29 0 .20 3 .80 4 .50 43 6.17 8.95 1.87 1.45 0.18 0.17 4 .60 4.90 46 6.30 8 .80 1.60 1.70 0.20 0 .05 3.90 4 .10 50 7.00 9.90 1.80 1.80 0 .05 0.18 4 .50 4 .50 53 5.50 7.90 0.97 1.30 0 . 3 1 0.06 4 .60 3 .90 60 6.60 11.40 0.28 0.32 0.32 0.36 6 .30 5 .30 Mean 5.37 7.26 0 .69 0.49 0.12 0 .09 3 .87 3.94 O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f rom S e c t i o n 5 . 1 . 4 1s t O r t h o - P 2nd (mg/L) NO3 + NO 1s t 2nd 2 (mg/L) Day # Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 2 4 .40 3 .30 0 .33 0.37 0 .10 0 .04 4.40 4.30 4 4.20 5.90 0.30 0 .20 0 .05 0.07 4 .40 4 .40 8 5 .30 7.70 0 .87 0 .60 0 .05 0. 17 3.90 3 . 8 1 11 6.00 7 .60 0.88 0 . 6 1 <0 . 0 1 < 0 . 0 1 3 .90 3 .50 15 7.30 8.70 0 .97 0 .97 0 .02 0 .02 4.10 4 .00 18 5.50 6.20 0.18 0 . 2 1 0 .03 0.03 2 .90 2 .40 22 8.42 9 .32 0.20 0.15 0.02 0.06 3 .70 3.70 25 7 .70 8.90 0.06 0.07 0 .08 0.14 3 .70 2 .70 29 7.90 9 .10 0 .04 0 .05 0 .01 0 .24 3 .30 3 .10 32 5 .80 7.50 0 .02 0.05 <0 . 0 1 0.03 4 .90 3.30 39 8.00 8 .40 0 .74 <0 .02 <0 .02 0 .08 3 .50 3 .10 Mean 6 . 4 1 7 . 5 1 0.42 0 .30 0 .03 0.08 3.88 3.48 - 1 6 3 -O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f rom S e c t i o n 5 .2 O r t h o - P (mg/L) N 0 3 + NO 2 (mg/L) 1s t 2nd 1 s t 2nd Day # Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 3 3.74 8.00 0.76 0 .75 0.19 0 .32 6 .30 5.40 7 2 .70 7.40 0 .36 0.35 0.16 0.05 5 .80 5 .40 14 2.00 11.00 0.42 0.34 0.26 0.15 6 .90 6 .60 17 0 .51 12.00 0.12 0.69 0.12 0.06 6 .20 5 .20 21 0.50 15 .50 0 .06 0.06 0 .34 0.26 8.00 7.70 24 0.48 16 .50 0.07 0.06 0 .25 0.08 6.83 7.10 28 0 .22 12.00 0 .20 0 .14 0.23 0 . 1 1 6.30 6 .30 31 0 .21 10.40 0.34 0.24 0.67 0 .04 5 .80 6 .00 38 0.40 8 .00 0 .03 0.13 0.10 0.13 4 .00 3.30 43 0.48 9.10 0 .02 0.04 0 .30 0 . 2 1 5 .74 5 .62 45 0.10 9.20 0 .05 0.05 0 .06 0.15 2 .94 4 .40 49 0.19 8 .70 0.03 0.04 0 .57 0.03 6 .20 6 .40 52 0.75 10 .70 1.10 0 . 4 1 0 .06 0.03 6 .10 7.20 Mean 0.94 10.65 0.27 0.25 0.25 0.12 5.93 5 .89 -164-A P P E N D I X A 2 R A W D A T A F R O M C H A P T E R S I X P R I M A R Y S L U D G E F E R M E N T A T I O N R E S U L T S -165-COD, pH and MLSS Raw Data from Section 6.1 .1 COD (mg/L) pH MLSS (mg/L) Day # Raw Inf. Set t.Sewage Fe rm. 1 Fe rm. 2 Fe rm. 1 Fe rm. 2 1 214 115 5.90 5.70 ' - -2 285 139 6.15 5.80 - - • 3 297 139 - - - -4 256 152 6.20 5.95 - -5 297 139 6.05 5 .95 - -6 275 188 6.20 5.95 1230 2305 7 269 179 - - - -8 - 181 6.15 5.95 1300 2470 9 290 187 6.10 5.90 - -10 251 173 6.10 5.90 - -11 303 177 6.10 5 .90 - -12 320 223 6.25 5.95 1950 3210 13 303 179 - - - -14 307 202 - - - -15 322 243 6.05 5 .85 1510 2120 16 305 220 6.05 5.85 - -17 262 195 - - - -18 322 205 - - - -19 303 232 6.25 6.05 1060 2360 20 287 172 - - - -21 - 166 - - - -22 289 208 6.30 6.00 1160 2170 23 275 176 6.05 5.85 - -24 271 259 6.15 5.90 - -25 330 - 6.00 5 .80 - -26 29 7 185 5 .75 6 .00 1090 2110 27 309 206 6.00 5.75 - — 28 333 210 5.95 5 .75 - -29 279 212 6.05 5 .85 1180 2270 30 229 146 - - - — 31 245 158 6.00 5.75 - -32 276 174 6 .05 5.85 - -33 266 180 6.10 5.80 1330 281 0 34 235 162 - - - -35 284 158 6.00 5.70 - -36 278 180 5.95 5.65 - -37 276 184 6.00 5.70 - -38 260 172 6.00 5 .70 - — 39 264 181 5.95 5.75 - -40 266 181 6.10 5.80 1830 2710 41 254 152 6.15 5 .90 - -42 223 133 6.10 5.85 - -43 207 129 6.00 5.75 114 0 2520 44 225 153 5.90 5.75 - — Mean 277 179 6.05 5 .85 1344 2460 - 1 6 6 -COD, pH and MLSS Raw Data f rom Sect i o n 6 . 1 .2 COD (mg/L) PH MLSS (mg/L) Day # Raw I n f . S e t t .Sewage Fe r m . 1 Fe rm. 2 Fe r m . 1 Fe rm. 2 1 198 110 5.65 5.45 - -2 248 116 5.70 5.50 - -3 225 146 5.75 5 .55 2769 2 39 6 4 247 141 5 .75 5 .45 - — 5 210 141 5.80 5 .50 - -6 178 100 5 .65 5 .45 266 4 2297 7 178 112 5.75 5 .50 - — 8 - 133 5 .70 5 .45 - -9 223 140 5 .60 5 .30 - -10 225 162 5 .70 5 .45 2093 2232 11 219 140 5.80 5 .55 — — 12 220 137 5.85 5.45 - -13 237 141 5.80 5.45 2120 2318 14 208 137 5.90 5.50 - — 15 225 - 6.00 5 .55 — — 16 235 - 6.05 5.65 - — 17 266 - 6.05 5.65 1970 2044 18 333 - 6.05 5.7 0 1800 1853 19 299 145 6.00 5.65 - -20 213 84 6.00 5.65 1764 2667 21 204 118 5.95 5 .60 - — 22 223 141 5.95 5.60 — — 23 383 255 5.95 5 .60 — — 24 257 166 6.00 5 .65 1700 1880 25 221 156 5.95 5 .55 — — 26 244 154 6.05 5 .65 - — 27 238 162 6.05 5 .80 1640 1880 28 233 94 6 .00 5 .65 - — 29 213 102 6.00 5.65 — — 30 291 141 6.10 5.80 - — 31 287 129 5.55 5 .20 1530 194 0 32 217 90 5.95 5 .65 — — 33 221 143 5.95 5 .60 — — 34 254 102 5.90 5.55 - — 35 204 125 5.90 5 .60 19 3 0 2165 36 217 150 5.90 5 .60 - — 37 303 125 5.95 5 .60 - — 38 303 156 5.95 5 .60 2030 2020 39 295 160 5.95 5 .60 — — 40 258 139 5.95 5.60 - -41 - 164 5 .90 5 .50 1940 2090 42 272 158 - — — — 43 317 137 5.90 5 .55 - — 44 393 176 6.35 6.20 - — 45 327 176 5.80 5 .45 1410 2 110 46 242 142 5.90 5.50 — — 47 234 138 5.90 5 .50 - — 48 254 156 5.90 5 .60 2050 2190 Mean 250 140 5.90 5 .60 19 61 2139 - 1 6 7 -COD, pH and MLSS Raw Data f rom Sect i o n 6 .1 .3 COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . S e t t .Sewage Fe r m . 1 Fe rm. 2 Fe r m . 1 Fe rm. : 1 288 - 5.75 5 .60 750 810 2 279 171 5 .75 5 .45 - -3 238 156 5 .70 5 .40 - -4 271 171 - - - -5 240 175 - - - -6 247 133 - - 1240 705 7 221 152 - - - -8 224 152 6.10 5.90 83 0 320 9 215 136 5.85 5 .75 - -10 226 151 - - - -11 245 155 - - - -12 253 192 5.85 5.65 515 180 13 280 156 5 .70 5.45 - -14 245 175 5.65 5 .45 - -15 237 156 5.85 5 .50 1240 260 16 29 6 119 5 .70 5.40 - -17 222 146 - - - -18 19 9 19 7 5 .70 5.45 - -19 214 156 5.65 5 .30 190 19 5 20 - 123 5.55 5.10 - -21 283 121 5 .60 5 .15 - -22 224 143 5 .65 5.20 156 260 23 252 121 5 .80 5 .30 - — 24 243 119 5 .65 5.15 - -25 231 139 - - - -26 237 154 5 .60 5.15 - -27 233 146 - - - -28 241 168 - - - -29 239 172 5 .60 5 .10 1550 2810 30 244 139 5.55 5.15 - -31 215 162 5.55 5 .00 - -32 250 - 5 .40 4.95 - -33 228 - 5.45 5 .00 1770 3260 34 230 - 5.50 5.00 - -35 230 140 - - - -36 225 110 5 .30 4 .90 1760 3380 37 176 114 5 .30 4 .95 1570 3560 38 - 130 5 .45 4 .90 - -39 219 158 5.45 5 .00 - -40 233 16 4 5.50 5 .00 - -41 285 168 5 .50 5 .00 1840 4130 42 306 149 5 .50 5.00 1850 4590 43 269 149 5 .50 5 .00 2430 4010 44 207 103 5.50 5 .00 1900 4600 45 248 124 - - - -46 261 153 - - - -47 277 162 5 .60 5 .10 - -48 - - 5.55 5 .05 1430 4030 49 377 19 5 5 .50 5 .00 1740 3310 50 203 166 - - 1840 3230 - 1 6 8 -COD, pH and MLSS Raw Data f rom S e c t i o n 6 . 1 . 3 ( c o n t . ) COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . Se t t .Sewage Fe r m . 1 Fe rm.2 Fe r m . 1 Fe rm. 2 51 219 165 - - - -52 229 165 _ _ _ -53 300 184 _ -54 248 149 5.65 5.15 1200 2580 Mean 245 151 5 .60 5 . 15 1358 2433 COD, pH and MLSS Raw Data f rom S e c t i o n 6 . 1 . 4 COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . S e t t .Sewage Fe rm. 1 Ferm. 2 Fe r m . 1 Fe rm. 2 1 360 179 6.05 5 .90 - -2 411 208 5 .85 5 .70 - -3 370 216 5.85 5 .65 - -4 366 - 5 .85 5 .65 1888 1588 5 160 156 5.85 5 .65 - -6 146 117 5 .75 5 .65 - -7 135 115 - 5 .70 5 .60 - -8 168 129 5 .70 5 .60 2155 2400 9 175 146 5 .70 5 .60 - -10 222 173 6 .30 6.20 - -11 239 181 6 .40 6 .30 2395 2015 12 339 204 5 .75 5 .65 - -13 376 189 5 .70 5 .60 - -14 323 184 5.90 5.80 - -15 303 199 5 .70 5 .60 2135 2453 16 313 226 - - - -17 330 177 5.90 5.95 - -18 301 187 5.90 5 .70 - -19 368 182 5.90 5 .80 1337 1485 20 - - - - - — 21 - - - - - -22 325 19 9 5.85 5 .75 - -23 362 195 5 .60 5 .50 880 1150 24 357 195 5.70 5 .60 - -25 374 183 5.75 5 .55 - -26 323 172 5 .65 5.55 1685 1545 27 307 200 5.75 5.65 - -28 325 186 5.75 5 .65 - -29 337 179 6.00 5 .80 - -30 291 171 5.85 5 .65 1255 1400 31 291 158 5 .85 5 .70 - -32 300 220 5 .75 5 .65 - -33 351 168 5.85 5 .60 1205 1380 34 302 181 5 .70 5 .65 - -35 310 159 5.75 5.65 - -36 336 108 5 .70 5 .65 - -37 338 172 5.85 5.65 - -38 304 185 5.80 5 .70 - -39 295 185 6.00 5 .75 - -- 1 6 9 -COD, pH and MLSS Raw Data f rom S e c t i o n 6 . 1 . 4 ( c o n t . ) , COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . Set t .Sewaqe Ferm. 1 Fe rm.2 Fe rm. 1 Fe rm . 2 40 367 157 5.90 5.65 2085 1665 41 338 192 5 .70 5 .70 - -42 383 194 5.90 5 .80 - -43 410 151 5.95 5.90 - -44 293 - 5.90 5.75 1795 -45 291 174 5.90 5 .70 - -46 307 192 6 .15 5.90 - -47 263 148 5.95 5 .70 1805 2353 48 328 163 5.80 5.90 - -49 368 - 5.80 5.90 - -50 463 127 6.05 6.00 - -51 501 169 5.95 5.95 1935 1545 52 516 184 5.90 5 .85 - — 53 - - - - - — 54 401 144 5.90 5 .80 - -55 397 222 5.95 5.90 - -56 351 157 5.85 5 .80 - -57 551 145 5.90 5 .85 - -58 - 169 - - - -59 293 165 5.85 5.80 2165 1915 60 348 185 6.00 5 .95 - — 61 - 149 5.90 5.90 - -62 - 159 - - 1755 1875 63 320 - - - — — 64 348 172 - — — — 65 340 208 6.10 6.00 - -66 389 190 6.00 5.95 - -67 - 190 6 .00 6.00 - -68 332 19 6 5.90 5 .90 — — 69 366 200 - - — — 70 - - - — — — 71 - 233 6 .30 6.20 - — 72 383 218 6.00 5 .95 - -73 311 210 6.10 6 .00 - -74- 325 210 6.10 6 .00 - -75 335 223 6.10 6 .00 2234 2338 76 339 208 6.25 6.10 - -77 343 226 6.55 6.50 - — 78 351 251 6.20 6.10 1686 19 66 79 341 257 6.20 6.10 - — 80 374 216 6.00 5 .90 - -81 435 220 6.00 5.95 1422 1866 82 336 182 6.30 6 .10 - -83 311 191 6.30 6.20 - -84 423 241 6 .25 6 .20 - -85 622 245 6.30 6.25 1928 2040 86 382 195 6.30 6 .20 - -87 602 216 6.40 6.30 — — 88 519 187 - — — _ 89 718 178 - — — — - 1 7 0 -COD, pH and MLSS Raw Data f rom Sect i o n 6 . 1 . 4 ( c o n t . ) COD (mg/L) PH MLSS (mg/L) Day # Raw I n f . S e t t .Sewag e Fe rm. 1 Fe rm.2 Fe r m . 1 Fe rm.2 90 627 224 6 .40 6 .30 - -91 643 216 - - - -92 369 207 6.40 6.35 2012 219 8 93 444 199 6.30 6.20 - -94 336 203 6 .25 6.15 - -95 353 220 6.25 6.15 1665 1710 96 301 168 6 .25 6 .15 - -97 501 174 - - - — 98 431 174 6.40 6 .30 - -99 354 198 6.35 6.25 - -100 366 202 6.25 6 .25 1786 1906 101 401 229 6.30 6.25 - -102 328 158 - - - -103 332 158 6.50 6 .40 - -104 291 150 6 .70 6 .65 - — 105 279 158 6 .70 6 .60 - -106 411 174 - - 2434 2286 107 380 157 6 .75 6 .70 - — 108 440 172 6.65 6 .55 - -109 331 176 6.55 6 .50 2244 2378 110 3 39 184 6.5 0 6 .40 — -111 525 200 6.50 6.35 - -112 362 215 6.55 6 .45 — -113 331 231 6 .50 6.40 - -114 351 234 6 .40 6 .30 2516 3 05 4 115 332 198 6.40 6.25 - -116 339 210 6 .30 6 .20 - -117 465 217 6 .40 6.20 2912 3054 118 367 205 6 .30 6 .10 - -119 381 220 6.15 5.95 - — 120 444 224 6 .25 5 .95 2560 3704 121 374 203 6.35 6.20 - -122 386 199 6.35 6 .10 - -123 443 232 6.25 6.10 - — 124 415 242 6 .25 6 .10 3038 3152 125 343 244 6.20 6 .05 - — 126 380 234 6.20 6 .10 — — 127 528 230 6.15 6.10 - -128 333 211 6.15 6 .05 3286 3534 129 29 6 185 6.15 6 .05 - -130 29 6 248 6.20 6 .00 - -131 325 195 6 .20 6 .05 3236 2896 132 420 191 6 .20 5.95 - -133 3 29 210 6.10 5 .95 - -134 420 222 6 .10 5 .95 - — 135 319 181 - - - -136 332 181 6.15 5 .90 3004 2692 137 282 151 6.10 5.90 - -138 290 193 6 .10 5 .90 2676 2898 139 351 218 6 .20 6.00 - -- 1 7 1 -COD, pH and MLSS Raw Data f rom S e c t i o n 6 . 1 . 4 ( c o n t . ) COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . Set t .Sewage Ferm.1 Fe rm.2 Fe rm. 1 Fe rm . 2 140 347 197 6.15 5 .95 - -141 376 224 6.15 6.00 - -142 324 212 6.30 6 .10 2608 2918 143 320 201 6.15 6 .05 - — 144 346 197 6.20 6 .10 - -145 309 180 6.20 6.10 2554 2602 146 284 172 6.10 5.95 - -147 258 148 6.10 5 .90 - -148 252 176 6.05 5 .95 2304 3040 149 349 145 6 .05 6 .00 - — 150 243 137 6.05 6 .05 - -151 259 147 - - - -152 280 157 6.10 6 .10 - -153 306 145 6.10 6 .05 2706 2778 154 337 186 6.15 6 .15 - -155 300 165 6.15 6 .05 - -156 308 186 6.10 6 .05 3576 292 2 157 321 147 6.10 6 .05 - -158 - 112 6.15 6 .15 - -159 323 167 6.20 6.25 3748 4202 160 275 131 - - - -161 285 159 6.05 6.10 - -162 327 169 6.00 6 .05 - -163 291 167 6 .05 6.10 3872 4334 164 339 185 6.10 6 .10 - -165 283 181 6.10 6.15 - -166 299 187 6.15 6 .15 392 4 3626 167 267 179 6.15 6.25 - -168 263 158 6.05 6 .10 — — 169 325 193 - - - -Mean 351 187 6.10 6 .00 2310 2432 VFA Raw Data f rom S e c t i o n 6 . 1 . 1 Fe rmen te r 1 (mg/L as HAc) Fermente r 2 (mg/L as HAc) Day # A c e t i c P r o p i o n . B u t y r i c T o t a l A c e t i c Prop i o n . B u t y r i c T o t a l 1 30.3 18 .8 <2.0 4 9 . 1 86 .3 8 4 . 1 8 .8 179.2 2 35.9 20.5 <2.0 56 .4 4 1 . 3 * 3 1 . 0 3 .5 75 .8 3 16 .2 8.0 <2.0 24.2 17 .0 11 .4 <2.0 28 .4 4 15 .7 7.3 <2 .0 23 .0 29 .9 17.9 2 .2 50 .0 5 28 .5 11.7 <2.0 40.2 45 .6 26 .5 2 .5 74.6 6 7 2 6 . 1 16.2 <2 .0 42 .3 3 5 . 1 28. 2 2 .9 6 6 . 2 / 8 3 1 . 1 13 .7 <2 .0 44 .8 43 .9 3 2 . 0 2 .9 78 .8 9 25.5 14.5 2.3 42.3 44 .5 32 .3 <2.0 76 .7 10 22 .0 14.4 <2.0 36 .5 49 .6 39 .5 2 .4 91.4 11 38 .0 22.2 <2.0 6 0.2 5 6 . 1 45 .3 2 .4 103.7 12 36 .7 23 .2 5.0 64 .9 58 .2 49 .4 2 .5 107.9 13 38 .7 23.3 <2.0 62 .0 50 .6 41 .3 4 .4 96 .3 -172-VFA Raw Data from Section 6.1.1 (cont.) Fermenter 1 (mg/L as HAc) Fermenter 2 (mg/L as HAc) Day # Acet i c Propion .Butyr ic Total Acet i c Propion .Butyr ic Total 14 39 .8 23.5 <2.0 63.3 63.1 49 .9 <2.0 113.0 15 62.6 38.2 4.9 105 .7 115 .0 86.3 5.4 206 .7 16 49.3 25.7 <2.0 75.0 18 .6 11.6 <2.0 30.2 17 - - - - 34.2 21.1 <2.0 55.3 18 - - - - 44.9 28 .5 <2.0 73 .4 19 - - - - 27.5 16 .9 <2 .0 44.4 20 14.0 4.8 <2.0 18 .8 64.9 40.7 2.5 108.1 21 - - - - 40 .7 26 .7 3.4 70.8 22 22.7 10.6 <2.0 33.3 28 .0 17 .7 <2.0 45.7 23 19 .6 8.2 <2.0 27.8 68.0 45 .8 2.7 116.5 24 37.8 18 .2 <2.0 56.0 48.8 32.6 <2.0 81 .4 25 15.2 6.3 <2 .0 21.5 27.0 17.1 <2 .0 44.1 26 17.7 8.3 <2.0 26.0 - - - — 27 20 .0 9.2 <2 .0 29.2 59.4 42 .8 2.3 105 .0 28 14.0 6.2 <2.0 20.2 40.5 27 .9 <2.0 68.4 29 3 7.2 18.5 <2 .0 55.7 47.0 34.3 <2.0 81.3 30 21.5 9.7 <2.0 31.2 - - - — 31 14.2 7.6 <2 .0 21 .8 46 .7 36 .9 <2.0 83 .6 32 39 .6 21.5 <2.0 61.1 34.8 27 .4 <2.0 62.2 33 29.9 14.5 <2 .0 44.4 67.6 50.2 <2.0 117.8 34 26.9 12.9 <2.0 39 .8 61.3 44.3 2.2 107.8 35 33.0 16 .6 <2 .0 49 .6 62.1 44.6 2.3 109 .0 36 29 .4 14.1 <2.0 43.5 55.6 40.8 2.1 98.5 37 29.5 14.3 <2 .0 46.3 60.7 43.5 2.6 106 .8 38 23.1 11.9 <2.0 35.0 60.3 44.3 <2.0 104.7 39 23 .6 13.3 <2 .0 36 .9 63.4 47.0 2.7 113.1 40 20.3 10.6 <2.0 30.9 65.7 47.7 3 .0 116 .4 41 32.1 16 .9 2.5 51.5 63.1 45.1 3.0 111.2 42 15.8 10.4 <2.0 26.2 59.6 43.5 3 .5 106.6 43 21.9 13.3 <2 .0 35.2 51.2 38.7 2.2 92.1 44 22.7 15.9 <2 .0 38.6 53.1 41.1 2.6 96.8 Mean 27.6 14.7 0.5 42 .8 51.0 37.4 1.8 90.2 VFA Raw Data from Section 6 .1.2 Fermenter 1 (mg/L as HAc) Fermenter 2 (mg/L as HAc) Day # Acet i c Propion .Butyr i c Total Acet i c Prop ion .Butyr i c Total 1 31.7 22.1 7.9 61.7 14.1 10.7 2.0 26.7 2 17.2 13.7 <2 .0 30 .9 19 .9 20.3 2.3 42.5 3 32.5 31.8 <2.0 64.3 79.7 68.9 3.7 152.3 4 33.7 23.1 <2 .0 56 .8 30.7 27.3 <2.0 59 .8 5 37.8 33.6 <2.0 71 .4 51.9 43.3 <2.0 95.3 6 65.1 55 .9 3.2 124.2 54.0 47.2 <2.0 102 .3 7 10.8 11.8 <2.0 22.6 20.2 26.8 <2.0 47.0 8 3.8 9.4 <2 .0 13.2 27.9 31.9 2.2 61 .9 9 21.6 23.8 2.8 48.1 25.5 26 .9 <2.0 52.4 10 53.2 44.8 2.6 100 .6 36.3 38.3 2.1 76.7 11 25.4 27 .2 6.0 58.6 48.4 43.0 3.6 97.0 12 72.7 36.5 <2 .0 109.2 - 1 7 3 -VFA Raw Data f rom S e c t i o n 6 . 1 . 2 ( c o n t . ) Fe rmente r 1 (mg/L as HAc) Day # A c e t i c Prop i o n . B u t y r i c T o t a l Fe rmen te r 2 (mg/L as HAc) A c e t i c P r o p i o n . B u t y r i c T o t a l 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 66.6 61.9 79.6 73 . 1 71 .7 61 .6 73 .4 65 .9 62 .7 71.9 60 .3 62.5 62.5 91 .5 43 .2 159.3 68.8 59 .6 63.6 79 .3 6 5 . 1 69.5 7 8 . 0 76 .2 79 .3 81 .8 94 .5 64 .0 58 .0 73 .0 63 .0 6 3 . 0 64 .0 7 0 . 0 39 .4 36 .8 35 .4 50, 46, 48. 57, 54, 51 .5 50 .6 47 .7 48.9 56 .4 34 .0 25.0 5 4 . 1 51 .8 43 .6 46 .2 5 4 . 2 51 .7 47 .0 4 1 . 2 50 .4 52 .7 45.5 89 .3 58 .0 45.0 59 .0 51 .0 56 .0 54 .0 54 .0 4 .4 <2.0 3.5 <2 .0 <2.0 <2 .0 <2.0 <2.0 <2 .0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2 .0 <2 .0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 110.7 9 9 . 4 118.4 123 .4 117 .8 109.9 131 .1 120.2 114 .2 122.5 108.0 111.4 118.9 125.6 68 .2 213.4 120 .6 103.2 109.8 133.5 116 .8 116 .5 119.2 126 .6 132.0 127 .3 183.9 122.0 103.0 132 .0 114 .0 126.0 108.0 124.0 73 .3 9 7 . 1 66 .5 121.0 105.4 97, 115 114, 117, 129, 6 ,1 5 2 1 110.4 118.5 159 .8 16 0.2 192.2 111.3 129 .2 108.7 132 .8 9 7 . 8 9 7 . 0 94 .0 95 .8 9 7 . 1 101.2 9 3 . 0 72 .0 100.0 9 4 . 0 77 .0 9 6 . 0 100.0 100.0 71 .6 71.3 63 .6 86 .3 75 .3 72.5 9 0 . 0 94 .8 99 .6 101.0 9 6 . 6 9 8 . 7 8 0 . 1 6 3 . 7 94 .3 88 .2 8 6 . 4 86 .3 105.7 88 .2 8 4 . 1 72 .5 82 .5 81.5 8 5 . 1 78 .8 5 9 . 0 84 .0 5 7 . 0 57 .0 80 .0 85 .0 8 5 . 0 4 .5 2.3 3.2 <2.0 <2.0 <2.0 <2.0 <2 .0 <2.0 <2.0 <2 .0 <2.0 <2 .0 <2.0 <2.0 <2.0 <2.0 <2.0 <2 .0 <2.0 <2.0 10.8 <2.0 <2.0 <2.0 <2.0 <2.0 6 .0 <2.0 <2.0 <2.0 6 .0 7.0 149.4 170.7 133 .3 207.3 180.7 170.2 2 0 5 . 1 209 .3 216 .8 230 . 1 207.0 217 .2 239 .9 223 .9 286 .5 19 9.5 215 .6 195.0 238 .5 186 .0 181 .0 17 7.3 -17 8.3 178.6 186.3 173 .3 131.0 19 0 .0 151.0 132.0 182 .0 191 192 ,0 ,0 Mean 61 .8 43.9 0 .7 106.4 90 .9 7 0 . 1 1 .5 162 .5 VFA Raw Data . f rom S e c t i o n 6 . 1 . 3 Fermente r 1 (mg/L as HAc) Fermente r 2 (mg/L as HAc) Day # Acet i c P r o p i o n . B u t y r i c T o t a l Acet i c P r o p i o n . B u t y r i c T o t a l 1 59 .9 35.9 <2.0 95 .8 61.9 42.6 <2.0 104.5 2 57 .5 32 .9 <2 .0 9 0 . 4 65 .8 44 .0 <2 .0 109 .8 3 58 .4 34.9 <2.0 93 .3 6 6 . 1 44 .9 <2.0 111.0 4 33 .6 11 .7 <2 .0 45 .3 4 3 . 2 18 .1 <2 .0 61.3 5 39 .4 16 .9 <2.0 56 .3 4 4 . 0 19 .9 <2.0 63.9 6 5 3 . 3 26 .7 <2 .0 8 0 . 0 5 5 . 7 3 1 . 1 <2.0 86 .6 7 41.9 29 .4 <2.0 71 .3 33 .2 23 .3 <2.0 56 .5 - 1 7 4 -VFA Raw Data f rom S e c t i o n 6 . 1 . 3 ( c o n t . ) Fermente r 1 (mg/L as HAc) Fermente r 2 (mg/L as HAc) 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 4 1 42 43 44 45 46 47 48 49 50 51 52 53 54 Mean 43.5 32.6 <2.0 7 6 . 1 6 4 . 4 49.4 <2.0 113 .0 39 .4 3 3 . 1 <2.0 72 .5 3 5 . 1 32 .5 <2 .0 67 .6 60.5 46 .8 <2.0 107.0 8 2 . 1 62.7 <2.0 149 .0 54.5 4 1 . 1 <2.0 95 .6 47 .0 3 4 . 1 <2 .0 81.3 64.5 46.8 <2.0 111.0 70 .4 49 .7 <2.0 120 .1 71.3 51.9 <2.0 123.2 6 6 . 1 47.5 4 .5 118 .1 68.5 49.3 3.7 121.5 45 .7 29 .6 6 .5 81 .8 69 .6 51 .0 4 .7 125.3 53.5 36.8 2 .8 93 .1 78 .3 57 .7 5.4 141.4 66.2 49 .0 8.5 123.7 76 .0 56 .8 5 .0 138.0 87 .7 66 .3 7.4 161.4 86 .6 6 4 . 0 6.8 157.4 47 .7 38 .2 8 .5 94 .4 4 3 . 1 28.5 5 .8 77 .4 75.6 54 .6 <2.0 130.2 43 .7 5 5 . 1 <2.0 98 .9 58 .6 44 .4 <2.0 103.0 53 .5 37 .6 <2 .0 9 1 . 1 82 .2 67 .4 4 .2 153.8 69 .9 56 .9 6.5 133.3 59 .5 62 .2 6 .7 128 .4 59 .9 46.9 2 .4 109.2 71.5 48.9 2 .8 123 .2 71 .7 5 3 . 6 3.9 129.2 5 7 . 1 43 .7 4 .0 104.8 5 4 . 3 40 .8 10.6 105.7 57 .5 43 .6 4 . 1 105.2 81.5 62 .8 5 . 1 149.4 98 .5 69 .3 6 .2 174.0 29 .2 20 .2 1.5 50 .9 60 .7 44.6 2 .8 1 0 8 . 1 40.3 3 0 . 2 <2.0 70 .5 61 .8 47 .4 <2 .0 109 .2 6 7 . 1 57 .8 <2.0 124.9 7 5 . 5 60 .3 <2 .0 136 .0 69 .8 55 .6 <2.0 125 .4 7 9 . 4 63 .0 <2 .0 142 .5 43 .4 36 .8 <2.0 80 .2 8 7 . 0 67 .0 3 .8 157.8 113.8 9 0 . 2 4 . 7 208.7 9 9 . 2 76 .6 3 .5 179.3 124.5 9 9 . 1 6.3 229 .9 66 .3 50 .3 6 .0 122.6 8 0 . 1 60 .4 <2 .0 140 .5 61 .0 42.5 <2.0 103.5 76 .5 5 8 . 1 7 . 1 141 .7 64 .9 49 .8 3 .3 118.0 109.0 8 5 . 0 6 .7 200.7 86 .8 66 .6 1 1 . 1 16 4.5 92 .5 72 .8 6 .0 171.3 125 .0 97 .3 7 .2 2 29 .5 105.0 8 2 . 1 11.3 198 .4 111.0 86 .5 11.8 209.3 92 .4 72 .6 6 . 1 171 .1 68.9 53 .2 3 .8 125 .9 73 .2 5 7 . 8 7.0 138 .0 121.0 92 .9 12.5 226 .4 133.0 102.0 15 .5 250.5 70 .0 69 .2 11.6 150.8 73 .0 6 6 . 0 8.2 147.2 87.9 82 .8 9 . 4 180.0 56 .6 71 .7 8.6 136.9 9 8 . 4 89 .3 9 .2 19 6.9 122.0 111.0 5 .7 238 .8 89 .3 82 .1 8 .5 17 9.8 77 .7 73 .4 8.2 159 .3 75 .4 7 7 . 1 7 .4 159.9 120.0 112.0 9.4 241.4 84 .5 78 .6 6 .2 169.3 102 .8 82 .9 7.9 193 .6 94 .8 82 .9 8 .3 186.0 110 .0 92 .0 7.7 209 .7 123 . 1 106.2 15 .9 245.2 1 1 9 . 1 99 .9 6.3 225 .3 137.3 116 .3 8 .0 262 .6 79 .3 6 4 . 7 4 .4 148.4 8 5 . 0 69 .2 5.5 159.7 - 1 7 5 -VFA Raw Data f rom S e c t i o n 6 . 1 . 4 Fermenter 1 (mg/L as HAc) Fermento r 2 (mg/L as HAc) C l a r . Day# A c e t i c P r o p i o n B u t y r i c T o t a l A c e t i c P r o p i o n B u t y r i c T o t a l T o t a l 1 60.3 44 .7 <2 .0 105.0 79.0 67.6 6 .0 152.6 16 4.4 2 76 .4 5 9 . 0 <2 .0 135 .4 80 .2 6 3 . 4 6 .0 149 .6 132 .6 3 85.9 6 8 . 1 5 .3 159.3 85.9 72 .4 5 .3 163.6 17 9 . 1 4 79 .4 6 8 . 1 4 .8 152.3 84.5 73 .0 5 .3 162 .8 189 .8 5 8 1 . 1 70 .4 3 .9 155.4 92 .0 80.9 5 .3 178.2 17 5.4 6 82 .3 71 .4 5 .3 19 6.7 101.9 89 .5 5 .3 19 6.7 198 .6 7 8 2 . 1 70.5 5 .3 171 .9 104.4 98 .4 5 .3 195 .1 177.4 8 87.9 73 .2 5 .3 166.4 9 6 . 2 88.9 5 .3 190.4 207.0 9 100.3 85.3 <2 .0 185.6 107.0 97 .5 <2 .0 194.5 226 .0 10 109 .0 92 .9 <2 .0 201.9 119.2 105.2 <2 .0 224.4 222 .4 11 92 .0 77.2 8 .2 177.4 73 .9 65 .0 6 . 1 145.0 188.3 12 91.3 7 5 . 2 8 .2 174.7 100.7 89 .6 8 .2 198.5 210 .2 13 94.0 7 8 . 1 8 .2 180.3 106.0 89.0 8 .2 203.2 2 27 .0 14 92 .7 7 5 . 1 8 .2 176.0 93 .8 77 .3 8 .2 179.3 19 7.3 15 i £ 8 8 . 1 72 .2 8 .2 168.5 95.8 83 .7 8 .2 187.7 219 .0 1 D 17 75.0 57.9 5 .2 138 .1 7 6 . 1 72 .4 5 .2 153.7 17 7.3 18 63 .3 4 6 . 1 5 .2 114.6 76 .9 66 .8 5 .2 148.9 135 .4 19 60.3 42.5 5 .2 108.0 71 .8 57 .0 5 .2 134.0 169.2 20 21 22 46.4 29 .8 5 .2 81.4 73.2 58 .3 5 .2 136.7 184.7 23 65.2 48.9 4 .0 118 .1 77.8 63.9 6 .0 147.7 159.0 24 77 .2 59 .4 4 .0 140.6 80 .4 67 .5 5 .0 152 .9 164.7 25 64.3 50.9 2 .0 117 .2 76.5 70 .9 4 .0 151 .4 160.9 26 67 .0 55 .9 4 .0 127.3 88 .9 76 .0 7 .5 172.4 215 .9 27 66.9 5 4 . 1 4 .0 125 .0 85 .4 7 6.. 3 6 .0 167.7 255.9 28 67.3 51 .8 4 .0 1 2 3 . 1 84.0 75 .4 4 .0 163.4 19 7.7 29 55.2 40.5 4 .0 99 .7 79.5 6 7 . 1 6 .0 152.6 -30 54 .4 39.2 4 .0 97 .6 59 .9 51 .5 4 .0 115.4 175 .5 31 53.5 40.5 4 .0 98 .0 64.5 56 .8 4 .0 125 .3 158.4 32 5 6 . 1 4 3 . 2 4 .0 101.3 66 .8 5 7 . 1 3 .0 126.9 -33 53.8 41.2 2 .0 97.0 67 .7 54 .2 4 .0 125 .9 154.8 34 69 . 1 4 9 . 1 4 .0 122.2 81.5 62 .0 6 .0 149.5 154.4 35 65.6 42.5 2 .0 110 .1 85.0 62 .3 5 .0 152.3 157.7 36 61.8 42 .5 2 .0 106.3 67 .0 56 .3 2 .0 125.3 145 .5 37 46.5 36 .0 2 .0 84.5 73 .2 5 7 . 1 5 .0 135.3 166.3 38 67 .2 51.3 3 .0 121.5 67 .8 56 .4 3 .0 127.2 135 .2 39 62.0 4 9 . 1 3 .0 114 .1 72.2 63 .8 3 .0 139 .0 1 4 5 . 1 40 62 .0 52 .5 3 .0 117.5 75 .9 68 .8 3 .0 147.7 153 .2 41 73.5 61 .0 4 .0 138 .5 93 .0 83 .1 5 .0 181 .1 176.4 42 68.5 5 2 . 0 2 .0 122.5 85 .3 77 .0 4 .5 166 .8 170 .6 43 87.8 72 .5 2 .0 162 .3 87.8 73 .3 2 .0 163 .1 128 .9 44 76 .0 6 4 . 1 2 .0 142 .1 89 .0 78 .9 2 .0 169 .9 170 .9 45 69 .8 53.2 2 .0 125 .0 96 .2 91 .2 4 .5 191 .9 191 .3 46 77 .6 57 .0 2 .0 136 .6 9 6 . 5 78 .5 2 .0 177.0 188 .6 47 79.5 54.8 2 .0 136.3 102 .1 85 .0 4 .5 191 .6 201.7 48 86 .0 7 6 . 2 6 .0 168.2 90 .2 89 .5 6 .0 18 5.7 19 6 .5 49 84.9 70 .0 6 .0 160.9 87.6 83 .8 6 .0 17 7.0 195.6 50 83 .6 6 5 . 3 5 .0 153 .9 82 .9 7 4 . 0 6 .0 162 .9 177.8 - 1 7 6 -VFA Raw Data f rom S e c t i o n 6 . 1 . 4 ( c o n t . ) Fermente r 1 (mg/L as HAc) Fermente r 2 (mg/L as HAc) C l a r . : T o t a l Acet i c P r o p i o n B u t y r i c T o t a l T o t a l 175 .1 112.0 92 .6 6 .0 210.6 192 .1 176.0 106.0 9 6 . 8 7.5 210.3 221 .5 211.2 124.6 115.4 6 .0 246.0 238 .4 219.8 126.2 115.6 9 .0 250.8 264.8 201.3 121.4 9 6 . 8 6 .0 224.2 235.2 193 .5 110.6 91 .0 6 .0 207.6 226 .8 174.6 115.2 90 .0 5 .5 210.7 203.8 169.9 102.0 9 0 . 0 5 .5 197.5 191.5 152.7 115.2 9 3 . 2 5 .5 213.9 222.2 155.3 102.8 76 .0 5 .5 184.3 182.7 139.2 104.2 80 .6 5 .5 190.7 189.4 139 .9 93 .8 68 .3 5 .5 167.6 168.7 111.2 6 3 . 1 51 .0 4 .0 1 1 8 . 1 205.9 132.8 100.0 83 .7 8.5 192 .5 181 .1 160.3 95 .9 76 .7 6 .0 178.9 160.7 147.4 88 .4 78 .5 6 .0 172 .9 173 .2 127.8 90.5 83.3 6 .0 179.8 189.9 130.9 80.9 66 .0 3.5 150.4 154.5 104.7 71 .2 61 .3 3 .5 136.0 147.5 104 .1 76 .4 6 9 . 4 3.5 149.3 156.9 9 9 . 4 78 .0 6 6 . 0 3 .5 147.5 180.2 105.7 65 .9 57 .5 3.0 126.4 136.2 113.4 78 .2 61 .5 5 .0 144.7 135.5 9 6 . 1 6 0 . 1 53 .3 4 .0 117.4 130.4 89 .4 6 8 . 1 51 .8 4 .0 123.9 1 2 5 . 1 97 .3 65 .9 46 .3 4 .0 116 .2 119.8 82 .5 64 .0 4 2 . 1 2 .0 108 .1 119.2 81 .1 5 6 . 0 36 .0 2 .0 94 .0 113 .2 77 .4 61 .0 38.4 2 .0 101.4 106.7 94 .6 68 .2 40 .5 2 .0 112.7 121.5 63 .4 70 .2 35 .3 2 .0 107.5 132.2 88 .5 67 .8 28.5 2 .0 98 .3 101.0 86.0 70 .2 34 .8 2 .0 107.0 112.6 90 .4 69 .6 3 8 . 1 2 .0 109.7 111.3 83.8 62.2 3 6 . 2 2 .0 100.4 109.4 100.3 63 .3 37 .2 2 .0 102.5 111.8 92 .4 61 .2 38 .8 2 .0 102.0 101.3 87 .6 57 .6 35 .9 2 .0 95 .8 95 .8 73.2 64 .3 37 .9 2.0 104.2 105.2 62 .3 51 .5 3 2 . 0 2 . 0 85.5 110.6 69 .3 56 .0 32 .0 2 .0 90 .0 9 5 . 7 8 5 . 1 57 .9 29.9 2 .0 89 .8 87 .9 51 94.8 74.3 6.0 52 93 .9 7 6 . 1 6 .0 53 - - -54 110.0 9 5 . 2 6 .0 55 113.8 100.0 6.0 56 114.0 83 .3 4 .0 57 107.0 82 .5 4 .0 58 - - -59 98.5 70 .6 5.5 60 94 .4 72 .0 3.5 61 8 5.8 63 .4 3 .5 62 - - -63 - - -64 - • - -65 86.5 61 .5 5.5 66 80 .6 5 5 . 1 3.5 67 79.3 5 7 . 1 3.5 68 61 .4 45 .8 4 .0 69 - - -70 - - -71 75.4 51.9 5.5 72 90 .0 66 .3 4 .0 73 7 9 . 1 62.3 6.0 74 70 .5 5 3 . 3 4 .0 75 74.6 52.8 3.5 76 60 .5 42 .2 2 .0 77 5 9 . 1 41.5 2.0 78 5 7 . 1 40 .3 2 .0 79 59 .3 43 .4 3 .0 80 61.5 48 .9 3 .0 81 53.0 4 1 . 1 2 .0 82 51.4 36 .0 2 .0 83 59.3 36 .0 2 .0 84 52 .2 28.5 2 .0 85 52.8 26.3 2.0 86 50 .2 25 .2 2 .0 87 63.5 29 . 1 2 .0 88 - - -89 50.3 11 .1 2 .0 90 63 .6 22 .9 2 .0 91 58 .7 25.3 2.0 92 59 .3 29.6 2 .0 93 51.5 30.3 2.0 94 65 .0 33.3 2 .0 95 57.5 32.9 2.0 96 55 .2 30 .4 2 .0 97 46.9 24.3 2.0 98 40.3 20 .0 2 .0 99 4 4 . 1 23.2 2 .0 100 54 .2 28.9 2 .0 - 1 7 7 -VFA Raw Data f rom S e c t i o n 6 . 1 . 4 ( c o n t . ) Fe rmente r 1 (mg/L as HAc) Fermente r 2 (mg/L as HAc) C l a r . Day# A c e t i c P r o p i o n B u t y r i c T o t a l A c e t i c P r o p i o n B u t y r i c T o t a l T o t a l 101 63.6 28 .3 4 .0 95.9 65 .0 31.3 3 .0 99 .3 90 .2 102 - - - - - - -103 38.4 15 .4 2 .0 55.8 4 6 . 1 20.9 3 .0 70 .0 7 5 . 7 104 3 3 . 1 12.4 2 .0 44.5 43 .2 17.9 3 .0 6 4 . 1 72 . 1 105 39 .7 6 .9 2 .0 48.6 40.8 11.8 2 .0 5 4.6 60 .4 106 - - - - - - -107 33.7 7.9 3 .0 44.6 35.4 9 .9 3 .0 48 .3 53 .8 108 3 5 . 1 1 1 . 1 <2 .0 46.2 37.3 13 .7 <2 .0 51 .0 43 .8 109 33.6 11.9 <2 .0 45.5 39 .2 1 4 . 1 <2 .0 53 .3 57 .6 110 30 .9 11 .2 2 .0 44.2 3 5 . 1 12 .0 2 .0 4 9 . 1 49 .4 111 28 .6 10.9 2 .0 41.5 34 .7 14.8 2 .0 51.5 52 .7 112 22 .4 13.0 2 .0 37.4 36.2 16.4 2 .0 54 .6 55 .7 113 3 5 . 1 13.7 2 .0 50.8 4 1 . 1 16 .4 2 .0 59 .5 60 .3 114 47 .2 23 .2 3 .0 73.4 43 .4 23 .2 3 .0 69 .6 74 .5 115 45.9 23.8 3 .0 72 .7 50 .7 27 .7 3 .0 81 .4 81 .2 116 49 .3 28.2 3 .0 80.5 53 .5 32 .5 3 .0 8 9 . 0 92 .3 117 45.2 25.0 3 .0 73.2 59 .0 38 . 1 3 .0 1 0 0 . 1 101.6 118 41 .9 25 .0 2 .0 68.9 67 .3 4 1 . 2 3 .0 111.5 1 0 6 . 1 119 62.6 40.0 3 .0 105.6 97 .0 66 .3 4 .5 167.8 152.2 120 6 7 . 2 3 9 . 1 3 .0 109 .3 79 .0 5 3 . 3 4 .5 136 .8 138.4 121 65.2 41.3 3 .0 109.5 7 4 . 1 45.9 3 .0 123 .0 120 .0 122 64 .0 35 .9 3 .0 102 .9 74 .2 50 .0 4 .5 128.7 136.4 123 68.9 43.5 2 .5 114.9 74.3 51 .0 3 .5 128 .8 -124 68 .2 45 .3 2 .5 116 .0 7 3 . 1 50 .4 3 .5 127.0 132 .0 125 6 1 . 1 40.6 2 .5 104.2 76 .4 54 .0 3 .5 133 .9 145.4 126 72.3 51.2 2 .5 126 .0 6 7 . 1 44 .3 3 .5 114.9 154.2 127 65.5 44.3 2 .5 112.3 71 .6 49 .5 3 .5 124.6 140.0 128 66 .0 45 .8 2 .5 114.3 7 4 . 1 54 .3 3 .5 131.9 138 .2 129 73 .3 50.9 2 .0 126 .2 83 .0 58 .0 2 .0 143.0 151 .0 130 66 .5 44.9 2 .0 113.4 79 .4 59 .8 2 .0 141.2 146 .9 131 72 .4 49 .4 2 .0 123 .8 81 .8 57 .5 2 .0 141.3 148.7 132 66 .0 42 .3 2 .0 110.3 82 .7 58 .8 4 .5 146.0 153 .9 133 72 .4 50 .6 2 .0 125 .0 7 6 . 1 57 .0 2 .0 1 3 5 . 1 145.9 134 73 .3 48 .0 2 .0 123.3 81.6 58 .3 2 .0 143.4 1 5 0 . 1 135 7 4 . 1 4 3 . 1 2 .0 119 .2 78.8 52 .9 3 .5 135 .2 124.3 136 76 .3 45 .6 3 .5 125.4 9 5 . 0 66 .3 5 .5 166.8 168 .8 137 71.0 45.6 2 .0 118 .6 84.0 65 .0 5 .5 154.5 158.8 138 80 .3 5 2 . 0 3 .5 135 .8 8 6 . 1 6 4 . 0 5 .5 155 .6 167.8 139 75.0 45.2 3 .5 123.7 8 6 . 1 65 .3 3 .5 154.8 184.7 140 68 .4 44 .8 2 .0 115.2 83.4 6 3 . 1 5 .5 151 .9 17 4 . 1 141 7 9 . 1 51 .0 2 .0 132 .1 88.9 59 .4 3 .5 151 .8 157.8 142 60 .6 39 .0 2 .0 102 .6 72 .0 52 .0 3 .0 127.0 133.7 143 57.2 40.8 2 .0 100.0 70 .4 48.9 3 .0 122.3 119.8 144 5 6 . 1 41 .0 3 .0 1 0 0 . 1 62 .2 49 .6 3 .0 114.8 118.6 145 54.0 39 .2 2 .0 95.2 66.8 53.5 3 .0 123 .3 128 .7 146 58 .5 48 .8 3 .0 110.3 69 .0 55 .0 3 .0 127.0 126.0 147 62 .2 44.6 3 .0 109 .8 70 .4 62 .6 3 .0 136 .0 153.8 148 63 .9 49.6 2 .0 115 .5 71 .2 5 7 . 2 3 .0 131.4 129 .2 149 67.5 50.9 2 .0 120.4 74 .7 55 .7 3 .0 133.4 135 . 1 150 69 .0 48.9 3 .0 120.9 74 .7 5 4 . 4 3 .0 1 3 2 . 1 1 4 2 . 1 - 1 7 8 -VFA Raw Data f rom S e c t i o n 6 . 1 . 4 ( c o n t . ) Fermente r 1 (mg/L as HAc) Fermente r 2 (mg/L as HAc) C l a r . Day# A c e t i c P r o p i o n B u t y r i c T o t a l A c e t i c P r o p i o n B u t y r i c T o t a l T o t a l 151 63 .0 45.0 2 .0 110 .0 70 .4 50 .3 3 .0 123.7 128 .4 152 68 .9 47 .2 3 .0 119 . 1 7 0 . 4 52 .0 2 .0 124.4 138 .2 153 76.0 48.3 4 .0 128 .3 91 .0 62 .4 4 .0 157.4 177.9 154 78 .2 5 0 . 1 2 .0 130 .3 8 5 . 0 55 .9 4 .0 144.9 1 5 2 . 1 155 77.9 47.0 2 .0 126 .9 83 .3 55 .9 4 .0 1 4 3 . 1 158.8 156 71 .4 44.5 2 .0 117 .9 79 .7 49.3 2 .0 131.0 143.3 157 79 .7 41.9 4 .0 125 .6 91 .0 53 .3 4 .0 148.3 1 5 5 . 1 158 78 .7 43 .8 4 .0 126 .5 72 .2 41 .9 2 .0 1 1 6 . 1 121.0 159 77.9 42.3 2 .0 122 .2 82 .4 43 .6 2 .0 128 .0 123 .6 16 0 83 .4 47 .0 2 .0 132 .4 85 .3 47 .8 2 .0 1 3 5 . 1 1 3 5 . 1 161 83.3 48.3 2 .0 133 .6 101.3 58 .3 2 .0 161 .5 173 .9 162 9 3 . 0 56 .8 2 .0 151 .8 9 6 . 8 57 .6 2 .0 156.4 16 6.7 163 8 9 . 1 48 .0 2 .0 139 . 1 95 .0 5 7 . 0 2 .0 154.0 161 .2 16 4 8 7 . 1 50 .3 2 .0 139 .4 86 .3 5 1 . 1 2 .0 139.4 150 .6 165 85.0 5 1 . 1 2 .0 138 . 1 97 .0 54 .2 2 .0 153.2 159 .0 16 6 93 .0 49 .9 2 .0 144 .4 94 .3 5 3 . 2 2 .0 149.5 157.2 167 101.3 6 0 . 1 2 .0 163 .4 112.0 62 . 1 2 .0 1 7 6 . 1 165.0 168 117.5 7 5 . 2 2 .0 194 .5 120.0 74 .8 2 .0 19 6 .8 205 .8 169 97 .8 58 .7 2 .0 158 .5 98 .2 57.9 2 .0 1 5 8 . 1 178.5 Mean 69 .0 47.3 3 .4 119 .7 79 .0 5 9 . 1 4 .2 141.7 157.0 COD, pH and MLSS Raw Data f rom S e c t i o n 6.2 COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . Se t t .Sewage Fe r m . 1 Fe rm . 2 Fe rm. 1 Fe r m . 2 1 203 120 5 .85 5 .80 2310 2437 2 335 15 3 - - - — 3 266 159 5 .85 5 .80 - -4 281 15 3 6.00 5 .85 1900 35 39 5 349 157 6.00 5 .90 - -6 298 172 5 .85 5 .75 - -7 252 153 5 .80 5 .70 3136 2830 8 291 155 5 .90 5 .80 - — 9 244 151 5 .80 5 .60 - -10 299 173 5 .85 5 .60 - -11 272 196 5 .85 5 .65 3070 3210 12 256 179 5 .70 5 .50 - — 13 209 124 5 .50 5 .35 - -14 179 121 5 .50 5 .50 3407 3000 15 175 139 5 .70 5 .50 - -16 185 131 5 .70 5 .60 - -17 229 161 5 .75 5 .65 - -18 388 169 5 .85 5 .70 2680 3870 19 227 133 - - - -20 277 157 - - - . -21 324 189 6 .30 5 .80 2575 5611 22 340 189 6.35 5 .90 - -23 293 201 6 .40 5 .95 - -- 1 7 9 -COD, pH and MLSS Raw Data f rom S e c t i o n 6 .2 ( c o n t . ) COD (mg/L) pH MLSS (mg/L) Day # Raw I n f . Se t t .Sewage Fe r m . 1 Fe r m . 2 Fe rm. 1 Fe r m . 2 24 389 159 6 .35 5 .90 - -25 347 171 6.20 5 .85 - -26 341 161 6 .20 5 .75 - -27 379 183 6.25 5 .75 - -28 291 171 , 6.25 5 . 7 0 2600 7538 29 - - - - - -30 - - - - - -31 - - 5 .60 5 .50 - -32 271 175 - - - -33 287 163 5 .60 5 .45 5413 6350 34 - - 5.70 5 .45 - -35 318 122 5 .65 5 .40 36 234 128 5.60 5 .40 5161 4250 37 244 148 5 .65 5.45 - -38 244 144 5 .70 5 .50 - -39 248 144 5 .20 5 .10 3593 3400 40 186 118 5.75 5 .60 - -41 199 107 5 .80 5 .60 - -42 190 98 5.90 5 .65 3325 2672 43 184 109 5 .90 5 .65 - -44 201 93 5.95 5 .75 - -45 199 107 6 .00 5 .85 - -46 197 116 5.65 5 .45 2253 28 09 47 211 97 6.00 5 .75 - — 48 211 100 6.00 5 .90 - -49 211 104 5 .60 5 .45 4 161 2659 50 197 95 6 .05 5 .90 - -51 199 88 6.10 5 .90 - -52 247 - 6.05 5 .80 - -53 249 139 6.10 5 .85 2260 2790 54 247 146 6.00 5 .80 - — 55 323 142 5 .90 5 .80 - -56 290 137 5.40 5 .30 2643 2361 57 243 172 5 .90 5 .60 - — 58 361 144 5 .85 5 .65 - -59 304 - - - - -60 296 211 5.95 5 .65 3228 3019 61 384 197 5 .90 5 .60 - -62 250 216 5 .85 5 .55 3277 3 29 6 Mean 265 147 5 .80 5 .65 3166 3647 - 1 8 0 -VFA Raw Data f rom S e c t i o n 6 .2 Fermente r 1 (mg HAc/L) Fe rmen te r 2 (mg HAc/L) Day # Acet i c P r o p i o n . B u t y r i c T o t a l 1 44 .7 35.9 <2.0 80.6 2 46 .9 35 .5 2.2 84 .6 3 39 .2 28 .3 <2.0 67.5 4 45 .5 31 .5 <2 .0 77 .0 5 48.3 13.3 <2.0 61 .6 6 8 0 . 0 72.5 <2.0 152 .5 7 47.8 26 .5 <2.0 74.3 8 49 .2 26 .7 <2 .0 75.9 9 37 .6 17 .5 <2.0 5 5 . 1 10 - - - -11 - - - -12 7 0 . 1 28.9 <2.0 99 .0 13 88 .0 20.2 <2.0 . 108.2 14 4 2 . 2 30 .6 <2 .0 72 .8 15 43 .7 25 .6 <2 .0 69.3 16 80 .8 5 0 . 8 2 . 1 133.7 17 48 .0 18 .3 3 .1 69 .4 18 36 .7 16.2 <2.0 52 .9 19 22.5 20 .0 <2.0 42.5 20 - - - -21 19 .2 8.7 <2.0 27.9 22 17.8 8 .6 <2 .0 26 .4 23 22 .4 14.0 <2.0 36 .4 24 2 2 . 0 10.6 <2 .0 32 .6 25 29 .5 23 .0 <2.0 52.5 26 3 2 . 1 16.5 <2 .0 48.6 27 32 .0 21.2 <2.0 53.2 28 5 4 . 8 4 2 . 4 <2 .0 9 7 . 2 29 - - - -30 - - - -31 - - - -32 4 7 . 1 5 2 . 3 <2 .0 9 9 . 4 33 8 3 . 7 80 .0 <2.0 163.7 34 7 0 . 0 6 6 . 3 <2.0 136.3 35 50 .0 47.5 <2.0 97 .5 36 6 5 . 0 6 5 . 0 <2.0 130.0 37 80 .0 75 .0 5 .0 160.0 38 6 5 . 0 5 4 . 0 5 .0 124.0 39 68 .0 61 .0 5 .0 134.0 40 83 . 1 43 .4 2.5 129.0 41 68 .5 50 .4 <2.0 118.9 42 52 .8 2 8 . 1 <2 .0 80 .9 43 5 9 . 7 44.0 <2.0 103.7 44 5 6 . 3 4 0 . 1 <2 .0 96 .4 45 5 7 . 7 29 .0 <2.0 86 .7 46 49 .3 2 0 . 1 <2 .0 69 .4 47 63 .7 25.2 6 .2 9 5 . 1 48 4 3 . 7 2 8 . 1 <2 .0 71 .8 49 64 .0 33.5 <2 .0 97 .5 50 34 .0 19 .6 <2 .0 53 .6 Acet i c P r o p i o n . B u t y r i c T o t a l 6 9 . 1 59 .0 3.6 131.7 47.8 4 2 . 0 2 .6 92 .4 65 .7 5 5 . 2 3 .3 124.2 66 .9 5 3 . 0 3.0 122 .9 80.0 69 .0 <2.0 149.0 8 5 . 0 82 .5 <2 .0 167.5 63 .4 3 7 . 1 <2.0 100 .5 82 .2 39 .0 3 . 1 124.3 57 .3 44 .4 <2 .0 101.7 43.4 25 .8 <2.0 69 .2 85 .2 49 .8 4 . 1 1 3 9 . 1 86 .7 63 .9 <2.0 150.6 91 .4 59 .5 <2.0 150.9 101.0 5 6 . 1 <2.0 15 7 . 1 70 .5 6 7 . 1 <2 .0 137.6 51 .8 4 8 . 2 2 .4 102.4 7 3 . 1 5 5 . 1 <2 .0 128 .2 40.0 35 .0 <2 .0 75 .0 77 .2 5 9 . 4 <2.0 136 .6 82 .0 55 .5 <2.0 137.5 81.2 6 3 . 0 <2.0 144.2 81 .1 64 .9 <2.0 146 .0 62 .0 5 0 . 0 <2 .0 112 .0 62 .5 57 .5 <2.0 120 .0 78 .8 90 .0 86 .0 98 .0 85 .0 83 .0 8 5 . 0 9 6 . 0 7 8 . 1 71 .5 7 0 . 0 87.5 90 .0 59 .0 7 8 . 1 85 .8 58 .2 87 .3 104.5 6 4 . 0 91 .2 8 7 . 0 91 .0 89 .0 85 .0 7 6 . 0 93 .0 72 .0 61 .4 6 0 . 0 75 .5 7 0 . 0 47 .0 62 .4 59 .9 40 .6 4 6 . 7 6 5 . 7 <2 .0 <2.0 3.0 16 .0 10 .0 <2.0 7.0 <2 .0 <2.0 <2 .0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2 .0 <2.0 2 .7 142 .8 181 .2 176 .0 205.0 184.0 168.0 168.0 189.0 1 5 0 . 1 132.9 130.0 163 .0 160.0 106.0 140 .5 145.7 9 8 . 8 134.0 172 .9 - 1 8 1 -VFA Raw Data f rom Sect i o n 6 .2 ( c o n t . ) Fermente r 1 (mg HAC/L) Fermente r 2 (mg HAc/L) Day # Acet i c P r o p i o n . B u t y r i c T o t a l Acet i c P r o p i o n . B u t y r i c T o t a l 51 56 .6 19 .3 <2.0 75.9 80.6 62 .2 3 .2 146.0 52 34.9 20 .9 <2 .0 55 .8 101.8 63 .3 <2 .0 1 6 5 . 1 53 66 .4 27.9 <2.0 9 4 . 3 80.2 55 .9 <2.0 136 . 1 54 47 .7 2 1 . 1 2 . 0 7 0 . 8 89 .6 71 .7 <2.0 161.3 55 75.9 3 8 . 1 <2.0 114.0 91 .1 53 .6 <2.0 144.7 56 6 6 . 1 50 .4 2 .5 119.0 1 0 4 . 1 83.2 <2.0 187.3 57 64 .4 43.9 <2.0 108.3 77 .0 47 .4 <2.0 124.4 58 - - - - 69 .9 34 .3 <2.0 104.2 59 - — — — _ _ _ _ 60 47 .8 33 .7 <2 .0 81.5 78 .8 5 7 . 4 <2.0 136.2 61 58 .4 45.8 5.2 109.4 - - - -62 - - - - 71 .2 6 1 . 1 <2 .0 132.3 Mean 52.5 3 4 . 1 0 .7 87 .3 77 .8 60 .7 1.2 139 .7 COD, pH and MLSS Raw Data f rom S e c t i o n 6.3 COD (mg/L) pH MLSS (mg/L) Day # Raw S e t t l e d Fe rm . 1 Fe rm . 2 Fe rm. 1 Fe r m . 2 I n f l u e n t Sewage Low/H igh Low/H igh 1 254 156 6 . 4 0 / 6 . 8 0 6 . 4 5 / 6 . 9 0 2050 2190 2 234 143 6 . 5 5 / 7 . 2 0 6 . 6 5 / 7 . 4 0 - -3 - 114 6 . 3 0 / 7 . 2 0 6 . 7 0 / 7 . 0 0 - -4 302 167 6.8 5 / 6 . 8 5 7 . 0 5 / 7 . 0 5 - -5 306 16 3 6 . 3 5 / 7 . 5 5 6 . 4 5 / 7 . 5 0 2 17 0 2810 6 200 122 6 . 6 0 / 7 . 0 0 6 . 8 5 / 7 . 1 5 - -7 212 118 6 . 4 5 / 7 . 1 5 6 . 6 0 / 7 . 3 0 2510 2500 8 392 143 6 . 7 0 / 6 . 8 0 6 . 8 0 / 6 .90 - -9 28 5 143 6 . 6 0 / - 6 . 7 0 / - - -10 249 155 - / - - / - - -11 265 186 6 . 3 0 / 7 . 0 0 6 . 2 5 / 6 .85 1800 2650 12 249 180 6 . 5 5 / 6 . 8 0 6 . 6 5 / 6 . 8 5 - -13 261 167 6 . 5 0 / 7 . 0 0 6 . 6 5 / 6 . 9 0 - -14 276 176 6 . 6 0 / 7 . 5 0 6 . 6 0 / 7 . 1 5 2070 1890 15 27 0 - 6 . 4 5 / 6 . 9 0 6 . 5 5 / 6 . 8 0 - -16 277 147 6 . 4 5 / 7 . 3 0 6 . 3 5 / 6 .90 - -17 302 180 6 . 9 0 / - 6 . 8 5 / - - -18 270 182 6 . 9 0 / 7 . 2 0 6 . 9 0 / 7 . 1 5 1250 1590 19 306 194 6 . 7 5 / 6 . 9 0 6 . 8 0 / 7 . 0 0 - -20 270 188 6.6 0/ - 6 .7 0/ - - -21 318 17 6 6 . 7 0 / 6 . 9 0 6 . 8 0 / 7 . 0 0 1160 1260 22 265 17 6 6 . 5 5 / 6 . 9 0 6 . 6 0 / 7 . 2 0 - -23 445 172 - / - - / - - -24 307 176 6 . 6 0 / 7 . 0 0 6 . 5 5 / 7 . 6 0 - -25 311 184 6 . 7 5 / 7 . 3 5 7 . 0 0 / 7 . 7 0 1290 1160 26 282 139 6 . 8 0 / 7 . 2 0 6 . 9 0 / 7 . 8 0 - -27 315 176 6 . 9 0 / - 7 . 5 0 / - - -28 - 157 6 . 4 0 / - 6.8 0/ - 1460 1520 29 243 161 - / 7 . 2 0 - / 7 . 6 0 - -30 247 180 6 . 5 0 / 7 . 3 5 6 . 7 0 / 7 . 5 0 - -31 267 17 5 6 . 9 5 / 6 .95 7 . 1 5 / 7 . 1 5 - -- 1 8 2 -COD, pH and MLSS Raw Data from i S e c t i o n 6 .3 ( c o n t . ) COD (mg/L) pH MLSS (mg/L) Day # Raw S e t t l e d Fe r m . 1 Fe rm. 2 Fe rm. 1 Ferm.. 2 I n f l u e n t Sewage Low/High Low/H igh 32 278 186 6 . 8 5 / 7 . 0 0 7 . 1 5 / 7 . 5 0 - -33 249 184 6 . 7 5 / 6 .95 6 . 9 0 / 7 . 3 0 - -34 247 - 6 . 8 5 / - 7 . 1 0 / - - -35 263 - 6 . 9 0 / - 7 . 1 0 / - 810 950 36 254 20 2 6 . 9 0 / - 7 . 0 0 / - - -37 242 162 - / - - / - - -38 276 17 4 6 . 7 0 / 6 . 9 0 6 . 6 5 / 6 . 9 0 - -39 259 179 6 . 7 0 / 6 . 9 0 6 . 7 5 / 7 . 0 0 882 819 40 246 182 6 . 7 0 / 6 . 9 5 6 . 7 5 / 7 . 0 5 - -41 283 153 6 . 7 5 / 7 . 0 5 6 . 8 0 / 7 . 1 5 - -42 286 149 6 . 8 5 / 7 . 0 5 6 . 9 5 / 7 . 6 5 - -43 372 137 6 . 7 5 / 7 . 0 0 6 . 9 5 / 7 . 3 5 - -44 251 141 6 . 8 5 / 7 . 1 0 6 . 7 5 / 7 . 8 5 - -45 253 157 6 . 9 0 / 7 . 1 5 7 . 0 5 / 7 . 6 5 - -46 28 6 17 8 6 . 8 0 / 7 . 3 0 6 .9597 .40 - -47 272 182 6 . 7 5 / 7 . 2 0 6 . 8 5 / 7 . 3 0 - -48 260 17 6 6 . 8 5 / 7 . 1 0 6 . 9 5 / 7 . 3 5 - -49 254 178 6 . 7 5 / 7 . 1 0 6 . 8 5 / 7 . 3 0 576 119 8 50 255 15 0 6 . 7 5 / 7 . 0 0 6 . 9 0 / 7 . 5 0 - -51 247 144 6 . 7 5 / 6 . 9 5 6 . 9 0 / 7 . 5 5 - -52 405 130 6 . 8 0 / - 6 . 9 0 / - - -53 482 166 6 . 8 5 / - 7 . 2 0 / 7 . 2 0 724 620 54 251 174 - / - - / - - — 55 364 190 7 . 0 5 / 7 . 0 5 7 . 3 5 / 7 . 3 5 - -56 247 162 6 . 6 0 / - 6 . 7 5 / - 799 740 57 225 152 6 . 7 5 / 7 . 2 0 , 6 . 8 0 / 7 . 5 5 - -58 266 152 6 . 9 5 / 7 . 3 0 6 . 8 5 / 7 . 7 5 - -59 279 202 6.9 0 / - 7 . 1 0 / - - -60 380 16 5 6 . 7 0 / - 6 . 8 5 / - - -61 236 158 6.8 5 / 7 . 5 0 6 . 9 5 / 7 . 6 0 - -62 25 0 17 0 6 . 9 5 / - 7 . 0 5 / - 808 800 Mean 282 165 6 . 7 5 / 7 . 0 5 6 . 8 5 / 7 . 3 0 1357 1513 VFA Raw Data f rom S e c t i o n 6 .3 Fermente r 1 (mg HAc/L) Fermente r 2 (mg HAc/L) Day # A c e t i c P r o p i o n . B u t y r i c T o t a l A c e t i c P r o p i o n . B u t y r i c T o t a l 1 67 .0 59 .0 7.0 133.0 102.0 87 .0 7 .0 196.0 2 6 4 . 0 47 .0 <2.0 111.0 9 6 . 0 7 6 . 0 8 .0 180.0 3 60 .0 45.0 <2.0 105.0 92 .0 75 .0 5 .0 172.0 4 29 .0 20 .0 <2.0 49.0 107.0 75 .0 13.0 195.0 5 60 .0 44 .0 <2.0 104.0 72 .0 56 .0 <2.0 128.0 6 5 6 . 0 4 3 . 0 <2.0 9 9 . 0 61 .0 45 .0 <2.0 106.0 7 53 .0 36.0 <2.0 89 .0 84 .0 64 .0 13.0 161.0 8 5 8 . 0 42 .0 <2.0 100.0 84 .0 62 .0 <2.0 146.0 9 46 .0 34 .0 <2.0 80 .0 72 .0 54 .0 <2.0 126.0 1 0 - - - - - - - -11 55 .0 42.0 <2.0 97 .0 62 .0 61 .0 <2.0 123.0 12 5 4 . 0 45 .0 <2.0 9 9 . 0 7 9 . 0 69 .0 7.0 155.0 - 1 8 3 -VFA Raw Data f rom S e c t i o n 6.3 ( c o n t . ) Fermenter 1 (mg HAc/L) Day # A c e t i c P r o p i o n . B u t y r i c T o t a l T T 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 5 0 51 52 53 54 55 56 57 58 59 60 61 62 Mean 70.0 5 3 . 0 62 .0 7 4 . 1 66.3 70 .6 65.0 62 .5 56.2 55 .4 54.8 53 .5 50 .7 50.6 46.2 50.0 46.6 50.6 47 .4 4 5 . 1 37.6 38.0 33.2 26.5 36 .0 31.7 32.2 30 .6 33.8 33 .8 22.8 33.5 54.9 36.7 3 5 . 1 44.4 32.2 34.7 50.6 38.3 32.8 38.3 30.6 30.5 34.5 31.9 36.6 3 9 . 1 46.2 Fermente r 2 (mg HAc/L) A c e t i c P r o p i o n . B u t y r i c T o t a l 57 .0 44 .0 52 .0 58 .0 52 .0 47.5 4 4 . 1 37 .0 3 4 . 1 31 .8 30.6 28.3 30 .4 3 2 . 1 32 .8 31.0 27 .7 30.2 29 .5 25 .3 20 .5 20 .6 18.7 13.8 20 .8 17.2 17 .8 1 7 . 1 17 .2 17.8 12.6 18.2 26 .0 16.0 15.5 22 .2 14.5 16 .0 26 .4 22 .3 2 1 . 1 21 .3 18 .5 15 .7 17 .4 1 6 . 1 18 .8 19 .9 29 .4 <2 .0 <2 .0 <2 .0 <2 .0 3.2 3.4 3.2 3.3 <2.0 <2 .0 3 .5 <2 .0 3 .5 <2 .0 <2 .0 3 .5 3 .4 3 .5 3.5 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2 .0 <2.0 <2 .0 <2 .0 4 .0 <2 .0 <2 .0 4 5 4 4 <2 .0 <2 .0 1.0 127 .0 97 .0 114.0 1 3 2 . 1 121.5 121.5 112.3 102 .8 90 .3 8 7 . 2 88.9 81.8 84.6 82 .7 79 .0 84.5 77 .7 84.3 80 .4 70 .4 5 8 . 1 58 .6 51 .9 40 .3 56 .8 48 .9 50 .0 47 .7 51 .0 51 .6 35 .4 51 .7 80.9 52 .7 50 .6 66 .6 46 .7 50 .7 77 .0 64 .6 53.9 59 .6 5 3 . 1 51 .2 55 .9 5 2 . 0 5 5 . 4 59 .0 76 .6 104.0 102 .0 98 .0 111.0 117 .0 106 .0 98 .8 9 7 . 7 92 .8 82 .5 7 9 . 1 79 .9 69 .8 73.6 74 .3 77 .6 71 .0 62 .5 69 .8 64 .0 47 .2 49 .2 46 .8 4 5 . 1 47 .8 38.5 55 .4 40 .7 48 .5 49 .9 43 .6 43.8 39.7 69 .7 49 .5 54.9 51.6 59 .8 30 .2 47 .2 47 .5 51 .9 47 .3 38 .4 4 7 . 1 46 .3 33 .2 48.9 51 .3 66 .7 78 .0 9 6 . 0 96 .0 104.0 107.0 80 .9 7 7.6 76 .5 71 .9 5 9 . 2 58 .5 5 5 . 1 52 .3 53 .7 52 .7 55.5 5 0 . 0 4 4.5 51 .0 45.3 31 .2 33 .0 32 .5 32, 3 1 , 27 , 38. 28 , 34, 33, 29, 29 , 28, 54 .6 34 .6 33.8 39.4 41 .4 4 3 . 1 31 .3 32 .2 33.9 30 .3 28 .2 30 .8 3 1 . 1 25 .6 30 .0 27.7 50 .8 ,5 2 ,2 4 ,1 2 ,3 ,0 ,7 ,0 10.0 5 .0 6 .0 7.3 7 .6 5 .0 5 .0 6 .4 6.5 5 .0 5 .0 3.5 5 .4 10.0 6.6 6 .0 6 .0 5 .0 7 .1 5 .0 4 .6 5 .0 4 .0 <2.0 <2 .0 <2.0 4 .5 <2.0 3 .0 4 .5 <2.0 <2.0 <2 .0 3.0 <2 .0 <2.0 <2.0 <2.0 4 .0 3 .0 <2.0 <2 .0 <2 .0 5 .0 5 .0 5 .0 5 . 0 <2.0 <2.0 4 .0 192 .0 203 .0 200.0 222 .3 231.6 191 .9 181 .4 180 .6 171 .2 146.7 142.6 138.5 127.5 137.3 133 .6 139 . 1 127 .0 112.0 127.9 114.3 82 .8 87 .2 83 .3 77 .6 79 .0 6 5 . 7 9 8 . 3 68 .8 8 5 . 7 8 7 . 1 72 .6 73 .5 6 7 . 7 127 , 84, 88, 91 , 101.2 77 .3 81 .5 79 .7 85 .8 77 .6 71 .6 82 .9 82 .4 6 3 . 8 78.9 79 .0 121.5 3 1 ,7 0 -184-APPENDIX A3 RAW DATA FROM CHAPTER S E V E N USE OF PRIMARY SLUDGE FERMENTATION IN THE A C T I V A T E D SLUDGE PROCESS - 1 8 5 -COD, VFA, T o t a l P, TKN and MLSS Raw Data f rom S e c t i o n 7 . 1 . 2 COD (mg/L) VFA T o t a l P TKN MLSS SVI Raw S e t t . (mg HAc/L) (mg/L) (mg/L) (mg/L) Day# I n f . Sewage E f f . T o t a l I n f . E f f . I n f . E f f . A e r o b i c 1 360 179 - 164 .4 5.3 2 .0 31 .8 2 .3 - 5 3 . 4 2 411 208 - 132.6 6 .7 2 . 1 3 3 . 1 1.7 - 53 .4 3 370 216 - 179 .1 5 . 1 2 .0 3 1 . 7 2 .3 - 5 5 . 3 4 366 - 43 189.8 5.0 2 . 1 32 .7 2 .5 2530 51 .4 5 160 156 - 175 .4 4 .9 1.6 3 1 . 7 1.8 • - 51 . 1 6 146 117 - 198.6 5.4 - 33.3 - — -7 135 115 - 177.4 5.9 - 37.3 - - 48.5 8 168 129 26 207.0 4 .7 1.5 35 .7 2.3 2590 46 .3 9 175 146 - 226.0 5 .7 1.9 34 .2 2 .3 - 4 1 . 9 10 222 173 - 222.4 5 .6 2.2 34 .4 2.6 - 50 .8 11 2 39 181 55 188.3 5 .7 1.8 33 .8 1.6 2690 48 .3 12 339 204 - 210.0 6 . 1 2 .8 35 .4 2.4 - 47 .6 13 376 189 - 227.0 6 .0 - 3 6 . 7 - - 5 2 . 4 14 323 184 - 197.3 5 .8 - 33.7 - - 51 .7 15 303 19 9 32 219.0 5.8 1.9 34 .5 2 .0 2845 51 .0 16 313 226 - - 5.4 2 . 1 30 .6 1.7 — -17 330 177 - 177.3 4 .6 3.7 35 .8 1.9 - 5 3 . 4 18 301 187 60 135.4 5 .4 2.3 32 .4 1.9 2795 55 .5 19 368 182 - 169.2 5.9 2 .0 3 2 . 4 1.5 - 5 2 . 7 20 21 22 325 199 - 184.7 5 .5 2.6 33.9 1.9 3000 5 6 . 7 23 362 195 - 159.0 6.8 2 .7 3 6 . 2 2 .3 — 6 0 . 0 24 357 195 - 164.7 5 .8 2.6 37 .2 2 .6 - 6 0.0 25 374 183 60 217 .2 5.3 2 .5 34 .3 2.2 2500 6 4 . 0 26 323 172 - 215.9 6 .0 1.9 37 .7 2 .2 - 63 .6 27 307 200 - 255.9 6.0 - 38 .7 - — 6 5 . 3 28 325 . 186 58 197.7 6 .4 - 39 .0 - - 6 3 . 0 29 337 179 - 152 .6 6.3 1 .6 4 0 . 8 2 .2 2555 6 6 . 5 30 291 171 - 175.5 4 . 1 1.1 24 .7 1.7 - 61 .8 31 291 188 - 158.4 4 .9 1 .6 27 .7 1.7 — 6 1 . 1 32 300 220 60 - 4.9 1.6 28 .7 1.9 2650 67 .9 33 351 168 - 154.8 5 .4 1.4 31 .3 1.8 — 6 4 . 2 34 302 181 - 154.4 5 . 1 - 30.4 - — — 35 310 159 - 157.7 4 .9 - 3 1 . 1 - — — 36 336 108 52 145.5 5 .5 - 36.8 - - — 37 338 172 - 166.3 5.3 1.5 3 3 . 2 2 . 1 - 6 6 . 1 38 304 185 - 135.2 4 .7 1.6 30 .6 1.6 - 73 .7 39 29 5 18 5 70 1 4 5 . 1 4 .8 2 .2 30 .3 1.8 2645 75 .6 40 367 157 - 153.2 5 .6 2 . 1 33 .3 1.3 — 71 .6 41 338 192 - 176 .4 6.3 - 21 .8 -. — — 42 383 194 - 170.6 6 . 1 - 36.5 - - — 43 410 151 32 128.9 5.6 1.8 33 .5 1.7 2125 89 .4 44 293 - - 170.9 5 .3 1.6 3 0 . 1 1.8 - 9 0 . 0 45 291 174 - 191.3 7.4 1.9 28 .0 - - 92 .9 46 307 192 57 18 8.6 7 .4 2.0 27 .9 1.4 2085 86 .3 47 263 148 - 201.7 5 . 1 2 .2 27 .7 1.7 - 9 7 . 6 48 328 163 - 19 6.5 6 .0 - 3 1 . 1 - - — 49 386 - - 195 .6 6 .8 - 3 1 . 0 - - -- 1 8 6 -COD, VFA, T o t a l P, TKN and MLSS Raw Data f rom S e c t . 7 . 1 . 2 ( c o n t . ) COD (mg/L) VFA T o t a l P TKN MLSS SVI Raw S e t t . (mg HAc/L) (mq/L) (mq/L) (mq/L) Day# I n f . Sewage E f f . T o t a l I n f . E f f . I n f . E f f . A e r o b i c 50 463 137 71 177.8 6.9 2 . 1 3 2 . 0 1.6 1945 92 .5 51 501 169 - 192 . 1 6 .3 2.2 37 .2 1.6 - 94 .2 52 516 184 - 221.5 6.3 0.5 36 .3 1.7 - 88 .6 53 - - - - - - - - - 85.6 54 401 14 4 - 2 3 8 . 4 6.8 1.3 42 .0 1.6 - 76 .0 55 397 222 - 264.8 6 .2 - 34.8 - - -56 351 157 - 235.2 5.8 1.3 33 .8 - - -57 551 145 56 226 .8 6 . 1 0.2 36 .3 1.6 2450 87 .8 58 - 169 - - 5.3 <0.2 21 .2 1.8 - 86 .7 59 293 165 - 203 .8 4 .5 <0.2 32 .7 1.6 - 85.5 60 348 18 5 - 191.5 5.2 0 .6 3 2 . 2 1.9 - 86 .5 61 - 149 - 222.2 - - - - 2 39 5 85 .6 62 - 159 - - 6.6 - 43 .6 - - -63 320 - - - 5.6 - 37 .2 - - -64 348 172 - - 5.7 - 3 4 . 2 - - 85 .9 65 340 208 - 182 .7 5.3 1.4 32 .8 1.4 - 80.2 66 389 190 - 189.4 5.5 1.0 35 .6 1.4 - 83 .3 67 - 190 - 168.7 8 .0 0.8 47.6 1.4 - 84 .5 68 332 19 6 61 205 .9 5.5 0.9 28 .8 1.3 - '83 .6 69 7 n 366 200 — — 6 . 1 2 .0 35.6 - - -/ u 71 — 233 41 181 .1 5 .5 _ 32.8 1.3 _ 83 . 1 72 383 218 - 160.7 4 .7 2 . 1 30 .8 1.0 - 82 .4 73 311 210 - 173 .2 4 .9 1.4 28 .8 1.3 - 85.3 74 325 210 57 189.9 5 .0 1.7 29.6 1.3 - 7 7 . 2 75 335 223 - 154.5 5.6 1.8 32 .4 1.3 2746 61 .9 76 3 39 208 - 147.5 4 .6 - 26 .0 - - 7 9 . 2 77 343 226 - 156.9 4 .9 - 28 .4 - - 70 .0 78 351 251 56 180.2 4 .7 1.3 29 .4 1.4 39 82 62 .8 79 341 257 - 1 3 6 . 1 4 .9 1.0 29 .6 1.8 - 62 .8 Mean 332 183 53 184 .0 5 .64 1.72 33 .06 1 .79 2619 69 .6 O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f o r S e c t i o n 7 . 1 . 2 . Ortho-P (mg/L) N0 3 + U02 (mg/L) 1st 2nd 1s t 2nd Day# Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 4 2 .50 1 3 . 5 0 2.00 2.20 0.24 0 .34 9 .60 9.20 8 2.20 13 .80 2.10 1.60 0 .53 0.09 13 .40 12.50 11 5.30 11.90 2.20 1 .80 0 .43 0 .64 13.10 12 .70 15 2 .80 15.00 2.20 2 .00 0 .06 0.07 14 .30 13 .60 18 2.00 12 .00 2 .20 2 .30 0 .40 0.26 15 .10 15 .30 22 2 .60 9.20 2 .60 2 .80 0.23 0 . 2 1 14.20 13.10 25 3.10 13 .70 2 .40 2 .60 0 .06 0.26 14.10 14.10 29 2 .00 13.90 1.70 1 .60 0.56 0.36 13.90 13.20 32 1.80 11.90 1.40 1.90 0. 17 0.10 11 .30 12 .60 43 2 .40 12.10 1.60 1 .90 0 .30 0 . 1 1 14.10 1 3 . 7 0 46 2.10 11.00 1.90 2 .00 0 .20 0 .02 12 .40 11.40 - 1 8 7 -O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f o r S e c t . 7 . 1 . 2 . ( c o n t . ) O r t h o - P (mg/L) N0 3 + NO2 (mg/L) 1s t 2nd 1s t 2nd Day# Unaer . Unaer . A e r o b i c E f f . Unaer . Unaer . A e r o b i c E f f . 50 2 .80 11.50 1.90 2.10 0.27 0 .08 13.20 12 .60 57 3 .70 14.50 0.07 0 .24 0 .04 0 .25 12 .60 12.00 60 1.20 11.60 0 . 5 1 0 .50 0.17 0.03 15 .30 12 .70 67 2 .10 11.40 0.83 1.03 - - - -74 2 .67 12 .80 1.62 1.82 0. 27 0.28 12 .00 11.80 Mean 2 .58 12.49 1.70 1.77 0.26 0 . 2 1 13.24 12 .70 COD, T o t a l P, TKN and MLSS Raw Data f rom S e c t i o n 7 . 2 . 1 COD T o t a l P TKN MLSS SVI (mg/L) (mg/L) (mg/L) (mg/L) Day# I n f . E f f . I n f . E f f . I n f . E f f . A e r o b i c 1 281 - - - 25 .8 - 4089 215 .2 2 338 - - - 26.6 - 4238 215.9 3 261 21 3.73 1.19 23 .9 - 4210 1 9 1 . 1 4 257 - - - 23.0 - 3609 2 5 2 . 1 5 245 - - - 2 3 . 2 - - — 6 253 - - - 23.5 - - -7 276 19 4.32 2 .79 24 .8 - 4106 222 .8 8 246 - 3 .75 2.58 23 .8 - 3270 226 .3 9 242 - 3 .68 1 .74 22 .4 - 4150 215 .7 10 253 26 3 .64 1.83 21 .2 - 3435 250.4 11 231 - 3.50 1 .89 20 .4 - - 253 .6 12 256 - - - 22 .7 - - — 13 273 - - - 23 .8 - 3835 -14 330 24 4 .33 1.90 24 .6 - 39 68 209.2 15 346 - 3.75 1.72 23 .6 - 3995 215 .3 16 217 - 3.50 1.55 21 .8 - 3457 167.8 17 222 24 3.55 2 .08 20 .2 - 29 82 278.3 18 193 - 3.25 1.25 19 .6 - - 233 .8 19 136 - - - 14.4 - — — 20 146 - - - 11.9 - - — 21 180 26 2.92 1 .95 14.9 - 4647 182 .9 22 158 - 3 .05 1.56 14 .5 - 4409 182 .6 23 169 - 3.20 - 1 7 . 1 - 4443 191.3 24 196 22 3 .50 2.07 16 .9 - 3873 213.0 25 254 - 3.52 1.87 17.4 - - 221 .9 26 - - - - — — — — 27 254 - - - 27.9 - - — 28 281 25 3 .99 2 .70 21 .2 - 316 7 145.2 29 199 - 3 .84 2.62 17.9 - - 252 .3 30 203 - 3.60 1.93 19 . 1 - - 226 . 1 31 172 25 3 .02 1.09 19.0 - - — 32 629 - 5.60 0.65 32 .6 - 382 1 212.0 33 18 5 - - - 19.3 - - 216 .5 34 - - - - - - 3845 206.8 35 - 30 3.67 1.84 - - - 207.5 36 194 - 4.12 2 . 0 1 22 .2 - 19 7.8 - 1 8 8 -COD, T o t a l P, TKN and MLSS Raw Data f rom S e c t i o n 7 . 2 . 1 ( c o n t . ) COD T o t a l P TKN MLSS SVI (mg/L) (mg/L) (mg/L) (mg/L) Day# I n f . E f f . I n f . E f f . I n f . E f f . A e r o b i c 37 211 - 3 .67 1.62 20.5 - 3880 208.8 38 185 22 3 .56 1.73 18 .8 - 3037 123.5 39 140 - 3.30 2.10 18.3 - 3816 197.9 40 224 - - - 18.4 — — — 41 197 - - - 17.0 - — — 4 2 244 18 3 .20 2.20 18 .7 - 4003 174.9 43 204 - 3.10 1.50 1 7 . 1 - 3000 140.0 44 201 - 2.89 1.54 16 .6 - 3719 200.3 45 - - - 1.30 - - 3604 216 .4 46 278 - 3.14 1.77 19.6 - 3616 217 . 1 47 173 - - - 18 .6 — — — 48 220 - - - 19.5 — — _ 49 235 20 3.00 2.10 1 9 . 1 — 3561 205 .0 50 404 - 4.5 0 1.40 20.6 - 3518 204.7 51 250 - 3.10 1.40 19 .8 - — 201.8 52 209 25 3 .00 1.30 19 .4 — — 190 .4 53 186 - 2.90 1.70 17.9 - — 181.9 54 19 4 - - - 18 .5 — — — 55 - - - - 10.5 - — — 56 225 21 3 .60 1.70 22 .0 - - 213.2 57 - - 3.47 1.56 21 .2 - - 213 .2 58 - - 3.18 0.83 20.2 — - 218.9 59 231 26 3 .25 1.00 - — — 207.5 60 203 - 3.52 1.10 — — _ 207.5 Mean 236 24 3 .54 1.72 20.2 3777 207.3 O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f o r S e c t i o n 7 . 2 . 1 Day# O r t h o - P (mg/L) NO3 + NOo (mg/L) A n a e r . Anox ic Ae r o b i c E f f . Anaer . An 0 x i c . Ae ro b i c E f f . 10 5 .48 2 .85 2.27 2.12 0 .04 0 .35 3 .36 2.20 17 3 .85 2.39 2 . 2 1 2 .34 0 .20 2 .58 — 2 .82 24 4 .50 2.65 2.15 2.15 0 .03 0 . 1 1 3 .10 2 .20 38 2.73 2.13 1.99 2 .10 0.09 2 .20 6 .04 2 .94 49 4 . 1 1 1.94 1.42 1.97 0.14 0.13 4 .02 6 .42 56 2.62 1.31 0.90 0 .98 0 .03 0 . 3 1 3.24 1.84 Mean 3 .88 2 . 2 1 1.82 1.94 0 .08 0 .94 3 .95 3 .07 COD, VFA, T o t a l P, TKN and MLSS Raw Data f rom S e c t i o n 7 .2 . 1 COD (mg/L) VFA T o t a l P TKN MLSS SVI Raw S e t t . (mg HAc/L) (mq/L) (mq/L) (mg/L) Day# I n f . S e w a g e E f f . T o t a l I n f . E f f . I n f . E f f . A e r o b i c 1 381 220 152.2 6.90 - 43 .8 - - 89 .8 2 444 224 51 138.4 7 .30 0 .92 40 .4 1 .9 3368 102.4 3 374 203 30 120.0 5.90 1.70 - - 142 .8 - 1 8 9 -COD, VFA, T o t a l P, TKN and MLSS Raw Data f rom S e c t . 7 . 2 . 2 ( c o n t . ) COD (mg/L) VFA T o t a l P TKN MLSS SVI Raw S e t t . (mg HAc/L) (mg/L) (mg/L) (mg/L) Day# I n f . Sewage E f f T o t a l I n f . E f f . I n f . E f f . A e r o b i c 4 386 199 - 136 .4 6.10 2.10 - - - 134.5 5 443 232 - 128 .8 6 .00 2.20 34 .0 1.4 - 160.2 6 415 242 - 1 3 2 . 1 6 .80 2.10 33 .2 1.6 3620 154.7 7 343 244 - 145.4 6 .40 - 32 .4 - - 123.6 8 380 234 - 154.2 6 .20 - 36 .0 - - 144.8 9 528 230 45 140.0 5 .50 1.70 32.8 1 .9 - 111.4 10 333 211 - 138.2 5 .50 1.20 32 .6 1.2 3701 1 0 8 . 1 11 296 185 - 1 5 1 . 1 7.40 0.92 40 .4 1.4 - 101.8 12 29 6 218 47 146.9 5 .30 0.89 30 .4 1.6 - 111 .6 13 325 195 - 148.7 5.20 0.89 28 .4 1.7 3796 106.7 14 420 191 - 153.9 6.00 - 35 .6 - - -15 3 29 210 - 145.9 7.20 - 43.8 - 3895 125 .8 16 420 222 51 1 5 0 . 1 5 .80 1 .00 37 .4 1.3 - 126 .7 17 319 181 - 124.3 5 .50 1.20 36 .2 1.8 - 130.2 18 332 181 - 168.8 5 .80 1.40 33 .5 2 .2 4044 138.5 19 282 151 48 158.8 5.30 1.80 34 .4 1.7 - 140.0 20 290 193 - 167.8 6.10 0 . 9 1 31 .5 1.3 4099 131.7 21 351 218 - 184.7 6 .20 1.90 36 .7 1.7 - 139 . 1 22 347 19 7 - 1 7 4 . 1 6.30 2.40 36 .3 1.4 - 114 .6 23 376 224 32 157.8 6 .30 1.80 36.2 1.7 - 109.7 24 324 212 - 133.7 5 .4 0 2.20 31 .2 1.7 4101 -25 320 201 - 119.8 5 .50 2 .00 31.0 1.5 - 102.4 26 346 197 38 118.6 5 .50 2 .60 31 .0 1.6 - 105 .3 27 309 180 - 128 .7 5 .30 2 .20 29 .4 1.6 393 1 -28 284 172 - 126 .0 4 .70 2 .10 24 .8 1.4 - -29 258 148 - 153.8 4 .30 2 .30 26 .4 1.3 - 91 .3 30 252 17 6 32 129 .2 4.30 2.10 26 .4 1.3 3769 9 0 . 2 31 349 145 - 135 . 1 3 .80 2 .20 25 .2 1.4 - 93 .8 32 243 137 - 1 4 2 . 1 3 .80 1.90 23 .8 1.1 - 94 .8 3 3 259 147 31 128 .4 4 .00 1.80 24 .6 1.4 - 93 .0 34 280 157 - 138 .2 4 .50 2 .80 25 .8 1.1 - -35 306 145 - 177.9 5 .00 - 29 .2 - 3577 91 .3 36 337 186 - 1 5 2 . 1 5 .50 1.70 34 .4 1.1 - 92.3 37 300 165 39 158.8 5.30 1.30 32.8 1.4 - 94 .9 38 308 186 - 143 .3 4.60 0 . 9 1 29 .2 1.5 3589 94 .8 39 321 147 - 1 5 5 . 1 4 .50 0 .82 28 .8 2 .2 - 9 4 . 7 40 - 112 33 121.0 4.80 0.14 3 2 . 0 2 .0 - -41 323 167 - 123.6 4 .80 1 .16 30.8 2 .2 3571 92 .4 42 275 131 - 135.2 5 .60 0.78 34 .8 2 . 1 - -43 285 159 - 173 .9 5 .30 0.94 32 .6 1 .3 - 90 .3 44 327 169 37 166.7 5 .60 0 .99 35 .6 1.2 - 89 .3 45 291 167 - 161.2 4 .60 1.00 31 .4 1.5 3738 88.3 46 3 39 185 - 150.6 4 .80 0 .68 31 .6 1.3 - 86.3 47 283 181 33 159.0 4 .60 0 .62 29 .6 1.3 - 8 7 . 1 48 299 187 - 157.2 5 .00 0.72 30 .6 1.6 364 1 90 .6 49 267 179 - 165.0 4.20 0 .78 29 .6 1.3 - 89.3 50 263 158 - 205 .8 5 .10 1.10 36 .8 1.3 - 89.3 Mean 330 186 39 147.6 5.43 1.47 32 .4 1.5 3791 1 0 9 . 1 - 1 9 0 -O r t h o - P and N i t r a t e B i o r e a c t o r P r o f i l e s f o r S e c t i o n 7 . 2 . 1 O r t h o - P (mg/L) NO3 + N0 2 (mg/L) Day* Anaer . Anox ic A e r o b i c E f f . Anaer . An ox i c Aero b i c E f f . 2 9 .10 5 .40 2 .20 2 .20 0.35 5 .80 15 .70 15 .80 5 11.70 6.50 2.80 2.20 0.20 0 .67 13 .30 13.10 9 14.90 6.00 1 .60 3 .60 0.22 2 .50 11 .50 11 .60 12 14.50 3 .40 1.00 0.85 0 .43 3.5 0 12 .90 12 .50 19 10.30 5 .40 1 .70 1 .70 0.05 3 .80 13 .10 12 .10 23 9.00 4 .50 1.20 1.20 0.12 0 .34 12 .10 11 .30 26 10.70 5 .70 2 .50 2 .60 0.16 3 .10 11 .30 11 .50 30 7.70 4 .60 2.40 2.20 0.24 4 . 4 0 10 .60 10.30 33 9 .10 5 .40 1 .46 1 .7 0 0 .16 - 9.70 9 .00 37 11.10 5.90 1.20 1.20 0. 19 3 .10 13 .00 12 .40 40 11 .40 6.00 1 .30 1 .00 0 .23 1 .90 11 .10 11 .10 44 13 .30 7 .40 0.96 0.98 0.05 2 .30 12 .70 12.20 47 7 .30 3 .00 0 .40 0 .76 0 .29 2 . 6 0 11 .50 11 .50 Mean 10 .78 5.27 1.59 1.71 0.35 2 .74 12 . 19 11.88 

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