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Nutrient requirements for aerobic biostabilization of landfill leachate Temoin, Edmond Paul 1980

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NUTRIENT REQUIREMENTS FOR AEROBIC BIOSTABILIZATION OF LANDFILL LEACHATE by EDMOND PAUL TEMOIN B . A . S c , U n i v e r s i t y o f B r i t i s h Columbia, 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n THE FACULTY OF GRADUATE STUDIES (The Department o f C i v i l E n g i n e e r i n g ) We a c c e p t t h i s t h e s i s as conforming t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA . October 1980 (G) EDMOND PAUL TEMOIN - 1980. In presenting th is thes is in p a r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f ree ly ava i lab le for reference and study. I fur ther agree that permission for extensive copying of th is thes is for scho la r ly purposes may be granted by the Head of my Department or by his representat ives . It is understood that copying or pub l ica t ion of th is thes is for f inanc ia l gain sha l l not be allowed without my writ ten permission. Depa rtment The Univers i ty of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 ABSTRACT When s o l i d wastes a r e d i s p o s e d o f i n a s a n i t a r y l a n d f i l l , c o ntaminated seepage, known as l e a c h a t e can become a problem. High s t r e n g t h l e a c h a t e can be s u c c e s s f u l l y t r e a t e d u s i n g an a e r a t e d b i o s t a b l i z a t i o n l a g o o n , as l o n g as t h e s l u d g e age i s m a i n t a i n e d a t g r e a t e r than 20 days. The o b j e c t o f t h i s s t u d y was t o de t e r m i n e t h e n i t r o g e n and phosphorus r e q u i r e m e n t s o f a e r o b i c m i c r o - o r g a n i s m s t r e a t i n g h i g h s t r e n g t h l e a c h a t e , by i t s e l f and i n comb i n a t i o n w i t h domestic sewage. S p e c i a l emphasis was p l a c e d on d e t e r m i n i n g t h e e f f i c i e n c y o f m e t a l removal, as a f u n c t i o n o f n u t r i e n t l o a d i n g . In t h e f i r s t e xperiment, t h e n u t r i e n t l o a d i n g was v a r i e d i n a s e r i e s o f b i o l o g i c a l r e a c t o r s w i t h a 20 day d e t e n t i o n t i m e . The i n p u t f e e d was h i g h s t r e n g t h l e a c h a t e . The BOD5/N/P r a t i o was v a r i e d from 100/3.19/0.12 t o 100/5/1.1. The most e f f e c t i v e t r e a t m e n t was a c h i e v e d w i t h a n u t r i e n t l o a d i n g o f 100/3.19/1.11. When t h e n u t r i e n t l o a d i n g was i n c r e a s e d o r d e c r e a s e d from 100/3.19/1.11, t h e r e was an i n c r e a s e i n B O D 5 , suspended s o l i d s and meta l c o n c e n t r a t i o n s i n t h e t r e a t e d e f f l u e n t . At n u t r i e n t l o a d i n g s below 100/3.19/1.11, t h e mixed l i q u o r s l u d g e b u l k e d , w i t h t h e volume o f sl u d g e g e n e r a t e d d o u b l i n g from 0.022 t o 0.050 ml o f s e t t l e d s l u d g e p e r mg o f BOD5 d e s t r o y e d . In t h e second experiment, t h e h i g h s t r e n g t h l e a c h a t e was combined w i t h d o m e s t i c sewage i n p r o p o r t i o n s v a r y i n g from 0 t o 20% ( v o l . l e a c h a t e ) / ( v o l . l e a c h a t e & sewage). No n u t r i e n t s were added t o t h e r e a c t o r s but the B O D 5/N/P/ r a t i o v a r i e d from 100/24/4.3 t o 100/3.62/0.12. The b i o s t a b i l i z a t i o n system e f f e c t i v e l y t r e a t e d a l l t h e v a r i a t i o n s o f wastewaters. There was no c o r r e s p o n d i n g i n c r e a s e i n B O D 5 o r m e t a l c o n c e n t r a t i o n i n t h e t r e a t e d e f f l u e n t when a h i g h e r p r o p o r t i o n o f l e a c h a t e was added t o t h e r e a c t o r s . The s l u d g e d i d not b u l k even though t h e BOD^N/P r a t i o dropped t o 100/3.62/0.12. When t r e a t i n g l e a c h a t e i n an a e r a t e d b i o s t a b i l i z a t i o n lagoon w i t h a 20 day sl u d g e age, the r e q u i r e d n u t r i e n t l o a d i n g can be s i g n i f i c a n t l y r e d uced below the recommended BOD^/N/P r a t i o o f 100/5/1. At low v o l u m e t r i c BOD l o a d i n g s o f a p p r o x i m a t e l y 0.16 kg BOD a p p l i e d p e r 5 c u b i c meter, a low n u t r i e n t l o a d i n g o f 100/3.62/0.12 does not a d v e r s e l y e f f e c t t r e a t m e n t e f f i c i e n c y . However, a t a r e l a t i v e l y h i g h v o l u m e t r i c l o a d i n g o f 1.0 kg BOD^/cubic meter, the minimum n u t r i e n t l o a d i n g needed was 100/3.19/0.5. The i n c r e a s e i n v o l u m e t r i c l o a d i n g r e q u i r e d a c o r r e s p o n d i n g i n c r e a s e i n phosphorus i n p u t . When t h e n u t r i e n t l o a d i n g was s u f f i c i e n t l y reduced, t h e mixed l i q u o r s l u d g e b u l k e d and s e t t l e d p o o r l y . T h i s r e s u l t e d i n a h i g h l e v e l o f suspended s o l i d s i n the f i n a l e f f l u e n t . S i n c e the m e t a l s were bound t o the suspended s o l i d s , the m e t a l c o n c e n t r a t i o n i n t h e f i n a l e f f l u e n t ( a l s o i n c r e a s e d . TABLE OF CONTENTS ABSTRACT LIST OF TABLES LIST OF FIGURES ACKNOWLEDGEMENT CHAPTER 1 INTRODUCTION 2 AEROBIC BIOSTABILIZATION OF LEACHATE 2-1 Fundamental P r i n c i p l e s 2-1-1 De s i g n o f C o m p l e t e l y Mixed, no R e c y c l e B i o l o g i c a l R e a c t o r 2^-1-2 E n v i r o n m e n t a l F a c t o r s 2-2 M e t a l s 2-2-1 T o x i c i t y 2-2-2 M e t a l Removal 2-3 N u t r i e n t s 2-3-1 N i t r o g e n Requirements 2-3-2 Phosphorus Requirements 2-3-3 N u t r i e n t Requirement as a F u n c t i o n o f Sludge Age 2-4 Le a c h a t e Treatment Systems 3 RESEARCH RATIONALE 4 SYSTEM DESIGN AND EXPERIMENTAL TECHNIQUE 4-1 P h y s i c a l D e s i g n 4-2 Le a c h a t e and Sewage Sources and C h a r a c t e r i s t i c s 4-3 pH C o n t r o l 4-4 N u t r i e n t s 4-5 "Pure L e a c h a t e " Experiment 4- 6 "Combination" L e a c h a t e and Sewage Experiment DISCUSSION OF RESULTS 5- 1 "Pure L e a c h a t e " Experiment 5-1-1 BOD 5 5-1-2 Suspended S o l i d s 5-1-3 M e t a l s 5-1^4 N i t r o g e n and Phosphorus 5-1-5 M i c r o - o r g a n i s m s 5-1-6 Sludge 5-1-7 K i n e t i c s 5- 2 "Combination" L e a c h a t e and Sewage Experiment 5-2-1 BOD 5 5-2-2 Suspended s o l i d s 5-2-3 M e t a l s 5-2-4 N i t r o g e n and Phosphorus 5-2-5 M i c r o - o r g a n i s m s 5-2-6 Sludge 5-2-7 K i n e t i c s 3 Comparisons o f "Pure L e a c h a t e " Experiment and the "Combination" Experiment CONCLUSIONS AND RECOMMENDATION 6- 1 C o n c l u s i o n s 6-2 Recommendations f o r F u t u r e Research REFERENCES APPENDICES LIST OF TABLES TABLE I CONTINUOUS DOSE OF METAL THAT REDUCED AEROBIC ' TREATMENT EFFICIENCY I I CONCENTRATION OF METAL THAT INHIBITS THE GROWTH OF SEWAGE ORGANISMS I I I METAL REMOVAL EFFICIENCY IN WASTE TREATMENT PLANTS IV EFFECT OF TEMPERATURE ON NUTRIENT REQUIREMENT V EFFECTS OF LEACHATE ADDITION TO A DOMESTIC SEWAGE TREATMENT PLANT VI COMPOSITION OF LEACHATE AND DOMESTIC SEWAGE V I I NUTRIENT LOADINGS V I I I LEACHATE LOADING FOR ''COMBINATION" EXPERIMENT IX MIXED LIQUOR CHARACTERISTICS-"PURE LEACHATE" EXPERIMENT X SETTLED EFFLUENT CHARACTERISTICS-"PURE LEACHATE" EXPERIMENT XI FILTERED EFFLUENT CHARACTERISTICS-"PURE LEACHATE" EXPERIMENT XI I METAL CONCENTRATION IN MIXED LIQUOR SLUDGES - "PURE LEACHATE" EXPERIMENT X I I I EFFICIENCY OF METAL REMOVAL FROM REACTOR C ( l ) XIV NITROGEN AND PHOSPHORUS CONTENT OF MIXED LIQUOR SLUDGES IN "PURE LEACHATE" EXPERIMENT XV CHARACTERISTICS OF SETTLED SLUDGE FROM REACTOR C ( l ) XVI SUMMARY OF KINETIC PARAMETERS FROM "PURE LEACHATE" EXPERIMENT v i i LIST OF TABLES PAGE TABLE XVII CHARACTERISTICS OF FEED FOR "COMBINATION" EXPERIMENT 65 XVIII MIXED LIQUOR CHARACTERISTICS FOR "COMBINATION" 6 6 EXPERIMENT XIX SETTLED EFFLUENT CHARACTERISTICS FOR "COMBINATION"EXPERIMENT 67 XX FILTERED EFFLUENT CHARACTERISTICS FOR "COMBINATION"EXPERIMENT 68 XXI BOD 5 REDUCTION IN MIXED LIQUOR VERSUS APPLIED LOADINGS 69 XXII METAL CONCENTRATION IN MIXED LIQUOR SLUDGES-"COMBINATION" 72 EXPERIMENT XX I I I NITROGEN AND PHOSPHORUS CONTENT OF SLUDGES IN "COMBINATION" 74 EXPERIMENT XXIV SLUDGE PRODUCTION FOR "COMBINATION" EXPERIMENT 78 XXV SUMMARY OF KINETIC PARAMETERS FROM "COMBINATION" EXPERIMENT 79 XXVI SUMMARY OF KINETIC RESULTS 90 LIST OF FIGURES FIGURE 1 NUTRIENT REQUIREMENTS AS A FUNCTION OF SLUDGE AGE 2 TREND IN NUTRIENT PRICES 3 SCHEMATIC OF LABORATORY AEROBIC REACTORS 4 EFFECT OF PHOSPHORUS LOADING ON BOD 5 5 MIXED LIQUOR VOLATILE SUSPENDED SOLIDS VERSUS TIME FROM START-UP FOR "PURE LEACHATE" EXPERIMENT 6 EFFECT OF NITROGEN ON SUSPENDED SOLIDS LEVEL OF THE SETTLED EFFLUENT 7 EFFECT OF PHOSPHORUS ON SUSPENDED SOLIDS LEVEL OF THE SETTLED EFFLUENT 8 METAL CONCENTRATION VERSUS SUSPENDED SOLIDS IN SETTLED EFFLUENT 9 PHOTOMICROGRAPHS OF THE GEODERMATOPHILUS AND ZOOGLEA FORMS 10 SLUDGE SETTLING CHARACTERISTICS FROM "PURE LEACHATE" EXPERIMENT 11 EFFECTS OF NITROGEN AND PHOSPHORUS LOADING ON THE SLUDGE VOLUME PER CENT (SVPC) 12 MIXED LIQUOR VOLATILE SUSPENDED SOLIDS VERSUS TIME FROM START-UP FOR "COMBINATION" EXPERIMENT 13 SLUDGE SETTLING CHARACTERISTICS FROM "COMBINATION" EXPERIMENT 14 DETERMINATION OF K AND K FOR "PURE LEACHATE" EXPERIMENT USING MIXED LfQUOR BOD AND FILTERED BOD_ DATA 5 15 DETERMINATION OF Y AND K FOR "PURE LEACHATE" EXPERIMENT USING MIXED LIQUOR BOD AND FILTERED BOD^ DATA i x FIGURE LIST OF FIGURES Page 16 DETERMINATION OF K AND K s FOR "COMBINATION" 93 EXPERIMENT USING MIXED LIQUOR BOD AND FILTERED — BOD 5 -DATA 17 DETERMINATION OF Y AND K, FOR "COMBINATION" 94 d EXPERIMENT USING MIXED LIQUOR BOD 5 DATA X ACKNOWLEDGMENT The a u t h o r wishes t o s i n c e r e l y thank h i s s u p e r v i s o r , Dr. D. S. M a v i n i c , f o r h i s g u i d a n c e , genuine i n t e r e s t and encouragement d u r i n g t h i s s t u d y . V a l u a b l e a s s i s t a n c e was a l s o r e c e i v e d from Dr. R. D. Cameron and Mrs. E l i z a b e t h McDonald. In a d d i t i o n , Dr. E. E. I s h i g u r o was v e r y h e l p f u l i n t h e m i c r o b i a l i d e n t i f i c a t i o n work. CHAPTER 1 INTRODUCTION When s o l i d wastes a r e d i s p o s e d o f i n a s a n i t a r y l a n d f i l l , c o ntaminated seepage, known as l e a c h a t e , can become a problem. The c h a r a c t e r i s t i c s o f t h e l e a c h a t e depend on the depth and c o m p o s i t i o n o f the r e f u s e , t h e h y d r o g e o l o g y o f the s i t e , the age o f t h e l a n d f i l l , and t h e c l i m a t e . Some l e a c h a t e s c o n t a i n a h i g h c o n c e n t r a t i o n o f o r g a n i c m a t t e r and i n o r g a n i c i o n s , i n c l u d i n g m e t a l s ( 1 ) . S e v e r a l c a s e s o f p o l l u t e d groundwater, caused by m u n i c i p a l l a n d f i l l s , have been documented (2,3). In an attempt t o c o n t r o l groundwater o r r e c e i v i n g water d e g r a d a t i o n , the l e a c h a t e s h o u l d be c o l l e c t e d and t r e a t e d . A t many new l a n d f i l l s i t e s , p a r t i c u l a r l y t h o se i n a r e a s w i t h a h i g h water t a b l e , l e a c h a t e t r e a t m e n t systems a r e becoming mandatory. S i n c e t h e l e a c h a t e can have a much h i g h e r c o n c e n t r a t i o n o f o r g a n i c s and m e t a l s than d o m e s t i c sewage, i t has been q u e s t i o n e d whether c o n v e n t i o n a l t r e a t m e n t systems c o u l d h a n d l e the wastewater e f f e c t i v e l y . C h i a n and DeWalle (4) have r e v i e w e d the l e a c h a t e t r e a t m e n t systems and d e v e l o p e d a scheme o f t r e a t m e n t which i s a f u n c t i o n o f l a n d f i l l age. L e a c h a t e s from l a n d f i l l s l e s s t h a n seven y e a r s o l d a r e b e s t t r e a t e d by an a e r o b i c b i o l o g i c a l p r o c e s s . P h y s i c a l - c h e m i c a l p r o c e s s e s a r e most e f f e c t i v e i n t r e a t i n g l e a c h a t e s from o l d e r , more s t a b i l i z e d l a n d f i l l s . 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 o f o r g a n i c wastes i s a f f e c t e d by t h e i n t e r p l a y o f t h r e e f a c t o r s : n u t r i e n t s , m i c r o - o r g a n i s m s , and s u b s t r a t e . One f a c t o r which may be l i m i t i n g i n t h e o v e r a l l 2 mechanism o f b i o - o x i d a t i o n i s t h e r a t e a t which n u t r i e n t s e n t e r the c e l l . S u f f i c i e n t q u a n t i t i e s o f a v a i a l b l e n u t r i e n t s must be p r e s e n t i n a waste water u n d e r g o i n g t r e a t m e n t , such t h a t t h e m i c r o -organisms may grow and be a c t i v e . B i o l o g i c a l t r e a t m e n t systems were a p p l i e d t o wastewater, l a r g e l y domestic sewage, f o r a t l e a s t f i f t y y e a r s b e f o r e any s e r i o u s c o n s i d e r a t i o n was g i v e n t o the n u t r i t i o n o f the m i c r o - o r g a n i s m s . (5) The i s s u e o f n u t r i t i o n a l r e q u i r e m e n t s was f i n a l l y f o r c e d when i n d u s t r i a l wastes, o f a wide v a r i e t y and c h a r a c t e r , were s u b j e c t e d t o b i o l o g i c a l t r e a t m e n t , e i t h e r s e p a r a t e l y or i n a m i x t u r e w i t h domestic sewage. The o b j e c t o f t h i s study was t o determine the n i t r o g e n and phosphorus r e q u i r e m e n t s o f a e r o b i c micro-organisms t r e a t i n g a h i g h - s t r e n g t h , l a n d f i l l l e a c h a t e , both by i t s e l f and i n c o m b i n a t i o n w i t h domestic sewage. S p e c i a l emphasis was p l a c e d on d e t e r m i n i n g the e f f i c i e n c y o f m e t a l removal, as a f u n c t i o n o f n u t r i e n t l o a d i n g . 3 CHAPTER 2 AEROBIC BIOSTABILIZATION OF LEACHATE 2-1 Fundamental P r i n c i p l e s The use o f 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 systems t o t r e a t o r g a n i c wastewaters i s w e l l known. In such t r e a t m e n t , the o b j e c t i v e s a r e t o c o a g u l a t e and remove the n o n - s e t t l e a b l e c o l l o i d a l and d i s s o l v e d s o l i d s and t o s t a b i l i z e the o r g a n i c m a t t e r . The most f r e q u e n t l y used p r o c e s s e s a r e a c t i v a t e d s l u d g e , t r i c k l i n g f i l t e r s , and a e r a t e d l a g o o n s . M i c r o - o r g a n i s m s a r e p r i m a r i l y r e s p o n s i b l e f o r t h e p u r i f i c a t i o n o f t h e wastewater. Rapid p u r i f i c a t i o n depends on the u n r e s t r i c t e d a c t i v i t i e s and r e p r o d u c t i o n o f t h e organisms. The m i x e d - l i q u o r c o n t a i n s p a r t i c l e s o f f l o e , c o n s i s t i n g o f mixed s p e c i e s o f m i c r o -organisms and s u b s t r a t e . The s p e c i e s may i n c l u d e b a c t e r i a , y e a s t s , p r o t o z o a and r o t i f e r s , a l l l i v i n g t o g e t h e r i n a g e l a t i n o u s mass. Marked changes i n the c o m p o s i t i o n o f t h e wastewater, pH, o r temperature w i l l e f f e c t the m i c r o b i a l p o p u l a t i o n o f t h e mixed l i q u o r . T h i s can r e s u l t i n a change i n the t r e a t m e n t e f f i c i e n c y . 2-1-1 D e s i g n o f a Completely-mixed, No r e c y c l e , B i o l o g i c a l R e a c t o r There a r e two o p e r a t i o n a l parameters w i d e l y used i n d e s i g n i n g a b i o l o g i c a l system;the s o l i d s r e t e n t i o n time (6 C) and t h e f o o d t o m i c r o -organism r a t i o (F/M). The s o l i d s r e t e n t i o n time i s d e f i n e d as the "Mean C e l l R e s i d e n c e Time" (MCRT). Lawrence and McCarty (6) showed t h a t t h e r e l a t i o n s h i p between b i o l o g i c a l growth and s u b s t r a t e u t i l i z a t i o n can be f o r m u l a t e d i n t o two b a s i c e q u a t i o n s . The f i r s t d e s c r i b e s t h e r e l a t i o n s h i p between n e t r a t e o f growth o f m i c r o -organisms and r a t e of s u b s t r a t e u t i l i z a t i o n : where cbc d t ds d t Net growth r a t e o f mic r o - o r g a n i s m s p e r u n i t volume o f r e a c t o r (M/TL ) Rate o f s u b s t r a t e u t i l i z a t i o n p e r u n i t volume, (M/TL ) Y = Growth y i e l d c o - e f f i c i e n t K = M i c r o - o r g a n i s m decay c o - e f f i c i e n t (T "*") d X = M i c r o b i a l mass c o n c e n t r a t i o n o r m i x e d - l i q u o - ... v o l a t i l e suspended ^ o l i d s , (MLVSS) c o n c e n t r a t i o n , (M/L ) The second b a s i c e q u a t i o n r e l a t e s t h e r a t e o f s u b s t r a t e u t i l i z a t i o n , b o t h t o the c o n c e n t r a t i o n o f mi c r o - o r g a n i s m s i n t h e r e a c t o r and t o the c o n c e n t r a t i o n o f s u b s t r a t e s u r r o u n d i n g t h e organisms: ds = KX S d t V 0 (2) K +S s where: S = C o n c e n t r a t i o n o f s u b s t r a t e s u r r o u n d i n g the mi c r o - o r g a n i s m s , (M/L ) K = Maximum r a t e o f s u b s t r a t e u t i l i z a t i o n p e r u n i t weight o f m i c r o - o r g a n i s m s , (T ) Ks = S u b s t r a t e c o n c e n t r a t i o n when 3 d s / d t = K (M/L ) x v 2 In a c o m p l e t e l y mixed, no r e c y c l e b i o l o g i c a l r e a c t o r , 9^ and F/M a r e r e l a t e d i n t h e f o l l o w i n g manner: ^ = Y (F/M) - K (3) e d 5 The change i n r e a c t o r b e h a v i o r , caused by v a r y i n g n u t r i e n t l o a d i n g s , c o u l d be f o l l o w e d by m o n i t o r i n g t h e v a l u e s o f K, K^, Y and V 2«-l-2 E n v i r o n m e n t a l F a c t o r s In o r d e r t o a c h i e v e optimum t r e a t m e n t , t h e r e a r e s e v e r a l f a c t o r s which must be c o n t r o l l e d . S i n c e t h i s s t u d y c o n c e r n e d i t s e l f w i t h t h e e f f e c t s o f n u t r i e n t s on t r e a t m e n t e f f i c i e n c y , t h e o p e r a t i n g c o n d i t i o n s had t o be such t h a t no o t h e r c o n d i t i o n s were l i m i t i n g . (a) pH The pH o f a wastewater i s a key f a c t o r i n the growth o f mi c r o - o r g a n i s m s . Most organisms cannot t o l e r a t e pH l e v e l s above 9.5 o r below 4.0. G e n e r a l l y , t h e optimum pH f o r growth l i e s between 6.5 and 7.5 ( 7 ) . However, U l o t h (8) found t h a t , w h i l e t r e a t i n g a h i g h s t r e n g t h l e a c h a t e , w i t h a pH o f 4.0, t h e mixed l i q u o r pH r o s e t o 8.5, i f l e f t u n c o n t r o l l e d . T h i s system worked v e r y w e l l and no improvement was noted when t h e pH was bro u g h t down t o 7.0. Thus, i n t h i s study, t h e pH was not c o n t r o l l e d and a l l o w e d t o f i n d i t s own l e v e l . (b) • Temperature I t can be ex p e c t e d t h a t l e a c h a t e d i s c h a r g e d from an u n l i n e d r e f u s e s i t e d u r i n g t h e w i n t e r would have a v e r y low temperature, p o s s i b l y near f r e e z i n g . I t has been shown t h a t t h e r e a c t i o n r a t e o f mic r o - o r g a n i s m s d e c r e a s e s w i t h d e c r e a s i n g temperature, d r o p p i n g by o one h a l f w i t h e v e r y 10 C drop i n temperature, u n t i l some l i m i t i n g temperature i s r e a c h e d ( 7 ) . Thus, when d e s i g n i n g a f u l l s c a l e l e a c h a t e t r e a t m e n t system, t h e l e a c h a t e temperature c o u l d be an im p o r t a n t l i m i t i n g f a c t o r . 6 • •' ' ( In t h i s study, t h e t e m p e r a t u r e was m a i n t a i n e d a t 20° C. T h i s i s the s t a n d a r d temperature f o r d e v e l o p i n g p s y c h r o p h i l l i c organisms, commonly found i n t r e a t m e n t p l a n s ( 7 ) . At 20°C, t h e temperature would not be a l i m i t i n g f a c t o r and t h e r e s u l t s o f t h i s s t u d y might then be compared w i t h o t h e r work. (c) • D i s s o l v e d Oxygen and M i x i n g In o r d e r t o m a i n t a i n an a e r o b i c system, t h e d e s i g n e d d i s s o l v e d oxygen l e v e l i n t h e mixed l i q u o r must be k e p t above 1.5-2.0 mg/L (7). I n i t i a l l y , i t was thought t h a t t h e r e c o u l d have been a problem i n s u s t a i n i n g t h e p r o p e r d i s s o l v e d oxygen l e v e l , when such a h i g h s t r e n g t h waste was t o be t r e a t e d . However, U l o t h (8) demonstrated t h a t t h e c o m b i n a t i o n o f m e c h a n i c a l m i x i n g and d i f f u s e d a e r a t i o n c o u l d e a s i l y m a i n t a i n t h e minimum oxygen c o n c e n t r a t i o n needed. I t i s e s s e n t i a l t h a t t h e mixed l i q u o r s o l i d s be c o m p l e t e l y suspended i n the d i g e s t e r i n o r d e r t h a t t h e m i c r o - o r g a n i s m s a r e m a i n t a i n e d i n an a e r o b i c environment. The d i f f u s e d a e r a t i o n system employed d i d n o t s u p p l y s u f f i c i e n t m i x i n g a c t i o n and thus a m e c h a n i c a l mixer was i n s t a l l e d . (d) L i q u i d - S o l i d S e p a r a t i o n The t r e a t m e n t o f wastewater t a k e s p l a c e i n two phases; f i r s t , t h e a b s o r p t i o n and uptake o f m a t e r i a l i n t o and on t o t h e b i o l o g i c a l f l o e , and s e c o n d l y , t h e removal o f the b i o l o g i c a l f l o e from the l i q u i d phase. T a r r e r e t a l (9) showed t h a t t h e l i q u i d s o l i d s e p a r a t i o n parameters a r e j u s t as i m p o r t a n t as the b i o l o g i c a l k i n e t i c p arameters, i n t h e d e s i g n p r o c e s s . The optimum d e s i g n o f an a c t i v a t e d s l u d g e system i s t h e r e f o r e s t r o n g l y i n f l u e n c e d by the e f f i c i e n c y o f t h e f i n a l c l a r i f i e r . T h i s p o i n t was g i v e n s e r i o u s c o n s i d e r a t i o n i n t h i s s t u d y , s i n c e U l o t h (8) showed t h a t most o f t h e m e t a l s and BOD i n t h e mixed b l i q u o r was removed by t h e s e t t l i n g b i o l o g i c a l f l o e . 2^ -2 M e t a l s The e f f e c t o f metals' on an a e r o b i c t r e a t m e n t p l a n t i s v a r i a b l e , M e t a l s , p r e s e n t i n a wastewater, can d i s r u p t a t r e a t m e n t system. However, Cheng (10) has shown t h a t t h e amount o f m e t a l s , which a b i o l o g i c a l system can h a n d l e , i s h i g h e r than p r e v i o u s l y thought. N e v e r t h e l e s s , t h e a c t u a l amount o f m e t a l removal, which can be e x p e c t e d by a b i o l o g i c a l system, i s s t i l l u n c e r t a i n . 2-2-1 T o x i c i t y The R.A. T a f t S a n i t a r y E n g i n e e r i n g C e n t e r C i n c i n n a t i , Ohio has comp i l e d t e n pa p e r s i n t o a r e p o r t (11) c o n c e r n i n g t h e i n t e r a c t i o n o f m e t a l l i c wastes w i t h 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 . The r e p o r t i n c l u d e s an 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 e f f e c t s o f z i n c , copper, chromium, and n i c k e l and a m i x t u r e o f heavy m e t a l s on 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 . An e x t e n s i v e s u r v e y o f l i t e r a t u r e on s i m i l a r s u b j e c t s i s a l s o c o v e r e d . The t e c h n i q u e employed i n a l l o f t h e s e s t u d i e s i s s i m i l a r . I n c r e a s e s i n C.O.D., BOD,., suspended s o l i d s o r t u r b i d i t y , i n t h e f i n a l e f f l u e n t , were used as i n d i c a t i o n s o f t h e e f f e c t s o f m e t a l on t r e a t m e n t e f f i c i e n c y . T h i s r e p o r t i n d i c a t e d t h a t c o n c e n t r a t i o n o f t h e f o u r m e t a l s s t u d i e d , e i t h e r s i n g l y o r i n c o m b i n a t i o n s , i n c o n c e n t r a t i o n s up t o 10 mg/L i n t h e systems i n p u t , would produce, a t most, a 5% r e d u c t i o n i n t h e t r e a t m e n t e f f i c i e n c y , i n a c o n t i n u o u s a c t i v a t e d s l u d g e p l a n t . 8 B a r t h e t a l (12) conducted a s i m i l a r s t u d y , u s i n g a c o n t i n u o u s i n p u t o f heavy m e t a l s t o an a c t i v a t e d s l u d g e p l a n t . The r e s u l t s a r e summarized i n T a b l e I. TABLE I (12) CONTINUOUS DOSE OF METAL THAT GIVE REDUCED AEROBIC TREATMENT EFFICIENCY M e t a l C o n c e n t r a t i o n i n I n f l u e n t Waste mg/L Chromium (VI) 10 Copper 1 N i c k e l 1 t o 2.5 Z i n c 5 t o 10 A d i f f e r e n t method o f e v a l u a t i n g t o x i c i t y i s t o m o n i t o r the r e a c t i o n k i n e t i c s o f a m e t a l contaminated system, r a t h e r t h a n t h e change i n t h e BOD,, o f the e f f l u e n t . N e u f e l d and Herman (13) c o r r e l a t e d the e f f e c t o f heavy m e t a l s on t h e r a t e o f s u b s t r a t e u t i l i z a t i o n . S e v e r a l c o n c l u s i o n s were made: 1) I t i s p o s s i b l e t o m a i n t a i n a t h r i v i n g c u l t u r e o f a c t i v a t e d b i o t a i n t h e p r e s e n c e o f h i g h l e v e l s o f mercury, cadmium o r z i n c . 2) The e f f e c t o f m e t a l s can be f o l l o w e d by m o n i t o r i n g t h e m e t a b o l i c r a t e o f t h e m i c r o - o r g a n i s m s . The m e t a b o l i c r a t e was found t o be a f u n c t i o n o f the m e t a l c o n c e n t r a t i o n i n t h e b i o l o g i c a l f l o e . F o r cadmium and z i n c , t h e r a t e was c o n s t a n t u n t i l a t h r e s h o l d m e t a l c o n c e n t r a t i o n was r e a c h e d . Beyond t h i s t h r e s h o l d , the r a t e dropped o f f d r a m a t i c a l l y . The t h r e s h o l d l e v e l o f m e t a l i n the f l o e was 5 mg cadmium/gVSS f l o e and 25 mg Zn/gVSS f l o e . 9 No t h r e s h o l d e f f e c t was o b s e r v e d f o r mercury. 3) The e f f e c t o f m e t a l s i s m i n i m i z e d by i n c r e a s i n g t h e s l u d g e age (0 ). The s l u d g e age can be i n c r e a s e d w i t h o u t i n c r e a s i n g the c a e r a t i o n time, by c a r r y i n g a r e l a t i v e l y h i g h l e v e l o f mixed l i q u o r s o l i d s . The e f f e c t o f m e t a l s on t r e a t m e n t e f f i c i e n c y w i t h i n c r e a s e d s l u d g e age, becomes v e r y i m p o r t a n t when one c o n s i d e r s t h e type of t r e a t m e n t p l a n t used t o t r e a t a l e a c h a t e . A 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 l a n t l i k e the one used i n t h i s p r e s e n t study, can have a s l u d g e age of 20 days. Thus, the t o x i c e f f e c t o f t h e m e t a l s was e x p e c t e d t o be m i n i m i z e d i n t h i s p r e s e n t s t u d y . C a r t e r and McKinney (14) found t h a t t h e optimum i r o n l e v e l f o r f e e d t o an a c t i v a t e d s l u d g e p l a n t was 10 mg/L. I f s i g n i f i c a n t l y g r e a t e r o r l e s s i r o n was p r e s e n t i n t h e p l a n t i n f l u e n t , then the m e t a b o l i c r a t e slowed c o n s i d e r a b l e and a poor s e t t l i n g f l o e d e v e l o p e d . A g i v e n m e t a l c o n c e n t r a t i o n may be t o x i c t o some s p e c i e s o f m i c r o - o r g a n i s m s , but may s e r v e as a s t i m u l a n t t o the growth o f o t h e r s . S i n c e t h e b i o t a c o m p o s i t i o n o f an a c t i v a t e d s l u d g e p l a n t v a r i e s from time t o t i m e , i t i s d i f f i c u l t t o p r e d i c t the t o x i c e f f e c t s o f heavy m e t a l s . Poon and Bhayani (.15) s t u d i e d t h e t o x i c i t y o f m e t a l s t o sewage organisms. The " M i c h e a l i s - M e n t e n Model", o f enzyme i n h i b i t i o n , was a p p l i e d t o a mixed c u l t u r e and t o i n d i v i d u a l s p e c i e s o f m i c r o -organisms. The r e s u l t s a r e l i s t e d i n T a b l e I I . TABLE I I CONCENTRATION OF METAL THAT INHIBIT THE GROWTH OF SEWAGE ORGANISMS M e t a l , Ag N i Cr Cu Zn T o x i c C o n c e n t r a t i o n (mg/L) 5 5 > 25 >25 50 These r e s u l t s agree w i t h t h o s e r e p o r t e d i n the R.A. T a f t E n g i n e e r i n g Report (11) 2-2-2 M e t a l Removal 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 has been shown t o be c a p a b l e o f e f f e c t i v e l y removing m e t a l s i n wastewaters (8,16). However, the wide range o f r e s u l t s make i t a l l most i m p o s s i b l e t o p r e d i c t the removal e f f i c i e n c y o f new system. Cheng e t a l . (10) i n v e s t i g a t e d t h e mechanism w i t h which m e t a l s were t a k e n up i n t o t h e b i o l o g i c a l f l o e . At lower m e t a l c o n c e n t r a t i o n s , m e t a l was absorbed by th e f l o e , t h r o u g h the f o r m a t i o n o f m e t a l l i c - o r g a n i c complexes. A t h i g h e r c o n c e n t r a t i o n s , t h e m e t a l i o n s a r e p r e c i p i t a t e d from the s o l u t i o n , as w e l l as t a k e n up i n the f l o e . The h i g h , m o l e c u l a r - w e i g h t e x o - c e l l u l a r polymers o f the b i o f l o c c o n s i s t o f D e o x y r i b o n u c l e i c a c i d (D.N.A.) p r o t e i n , and p o l y s a c c h a r i d e s . These f u n c t i o n a l g r o u p i n g s a p p a r e n t l y a c t as b i n d i n g s i t e s f o r t h e m e t a l i o n s . M e t a l uptake by the s l u d g e depends on s e v e r a l f a c t o r s , i n c l u d i n g pH, and t h e c o n c e n t r a t i o n o f o r g a n i c m a t t e r and m e t a l s p r e s e n t i n the system. In g e n e r a l , t h e uptake c a p a c i t y i n c r e a s e s 11 w i t h i n c r e a s i n g pH. C o n v e n t i o n a l b i o l o g i c a l t r e a t m e n t removed 80% o f t h e copper, 50% o f t h e n i c k e l , and 95% o f t h e l e a d . (10). B a r t h e t a l (17) s u r v e y e d f o u r m u n i c i p a l wastewater t r e a t m e n t p l a n t s f o r heavy m e t a l removal. A l l t h e p l a n t s were a c t i v a t e d s l u d g e systems. The i n f l u e n t m e t a l l e v e l s i n t h e s t u d y were a l l below t h e 2 mg/L l e v e l . A l s o , B a r t h e t a l . ( 1 2 ) c o n d u c t e d a p i l o t p l a n t s t u d y , which used m e t a l c o n c e n t r a t i o n s i n the o r d e r o f 10 mg/L. The m e t a l removal e f f i c i e n c y i n t h e m u n i c i p a l p l a n t s compared w e l l w i t h t h e p i l o t p l a n t s f i n d i n g s . The r e s u l t s a r e l i s t e d i n T a b l e I I I . TABLE I I I (12, 17) METAL REMOVAL EFFICIENCY IN WASTE TREATMENT PLANTS M e t a l Removal E f f i c i e n c y (%) Cr Cu Zn N i — 1 P l a n t A 75 50 91 0 P l a n t B 31 0 47 10 P l a n t C 75 65 67 33 P i l o t P l a n t 44 75 89 28 2-3 N u t r i e n t s S u c c e s s f u l 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 depends on the p r o p e r b a l a n c e between n i t r o g e n , phosphorus and o r g a n i c m a t e r i a l . The recommended r a t i o i s B0D../N/P = 100./5./1 (7) ;. s m a l l q u a n t i t i e s o f b s e v e r a l o t h e r elements such as p o t a s s i u m , c a l c i u m , s u l p h u r and t r a c e m e t a l s a r e a l s o r e q u i r e d . These n u t r i e n t s a r e n o r m a l l y p r e s e n t i n domestic sewage i n s u f f i c i e n t amounts t o s a t i s f y t h e b a c t e r i a l demand. However, i n d u s t r i a l wastewaters are f r e q u e n t l y d e f i c i e n t i n n i t r o g e n and phosphorus, T h e r e f o r e , t h e s e elements must be s u p p l i e d as a n u t r i e n t supplement, i f t h e optimum e f f i c i e n c y o f t r e a t m e n t i s t o be m a i n t a i n e d . F o r example K r a f t - m i l l e f f l u e n t i n t h e p u l p and paper i n d u s t r y , i s d e f i c i e n t i n n i t r o g e n and phosphorus w h i l e d o m e s t i c sewage c o n t a i n s t h e s e elements i n e x c e s s . The a d d i t i o n o f domest i c waste t o a k r a f t -m i l l t r e a t m e n t p l a n t r e s u l t s i n e f f e c t i v e treatment; w i t h reduced n u t r i e n t c o s t s . (18) 2-3-1 N i t r o g e n Requirement Helmers e t a l . (19) conducted experiments on i n d u s t r i a l wastes, d e f i c i e n t i n n i t r o g e n and phosphorus. Wastewater from c o t t o n m i l l i n g and brewing were p r o c e s s e d i n an a c t i v a t e d s l u d g e system. They came t o the f o l l o w i n g c o n c l u s i o n s : 1) N u t r i e n t ' r e q u i r e m e n t ' s , based on BOD removal, were 5 not a f f e c t e d by temperature r a n g i n g from 10° C t o 30° C. T a b l e IV summarizes t h i s f i n d i n g . TABLE IV (19) EFFECT OF TEMPERATURE ON NUTRIENT REQUIREMENT j TEMP i ( ° c ) l b B0D 5 REMOVED l b N | REQUIRED j l b P ; REQUIRED ; i 1 \ 10 100 i 3 ! 0.6 T j 20 100 i 4 j i 0.7 I \ | 30 | 100 I 3 ! { I \ 1 0.5 i Maximum n u t r i t i o n a l r e q u i r e m e n t need not be i n o r d e r t o a c h i e v e s a t i s f a c t o r y t r e a t m e n t . 3) A n i t r o g e n d e f i c i e n c y r educed t h e r a t e o f B0D 5 removal, and i m p a i r e d the s e t t l i n g and d e w a t e r i n g c h a r a c t e r i s t i c s o f t h e s l u d g e . 13 4) The n i t r o g e n c o n t e n t o f t h e d r i e d s l u d g e , based on v o l a t i l e matter, was used as an i n d e x o f n i t r o g e n d e f i c i e n c y . A value o f l e s s than 7 mgN/100 mg VSS (7%) i s an i n d i c a t i o n o f a n i t r o g e n d e f i c i e n c y . S i m i l a r l y , a v a l u e o f l e s s t h a n 1.2 mg P/100 mg VSS (1.2%) i n d i c a t e d a phosphorus d e f i c i e n c y Sawyer (5) e s t a b l i s h e d a r a t i o o f n i t r o g e n t o phosphorus t o a p p l i e d BOD which s h o u l d be m a i n t a i n e d i f a e r o b i c m i c r o - o r g a n i s m s a r e t o f u n c t i o n e f f e c t i v e l y . The BOD5/N/P r a t i o s h o u l d be above 100/3.13/0.67. The a c c e p t e d n u t r i e n t v a l u e f o r t r o u b l e -f r e e t r e a t m e n t i s 100/5/1 (7) McKinney e t a l (20) d i s c u s s e d the r o l e o f n i t r o g e n i n a e r o b i c s t a b i l i z a t i o n o f o r g a n i c wastes and i n v e s t i g a t e d v a r i o u s forms o f n i t r o g e n supplements. A l l i n o r g a n i c n i t r o g e n , i n b o t h i n d u s t r i a l and domestic wastes, was a v a i l a b l e f o r s l u d g e growth, but o n l y a p o r t i o n o f o r g a n i c n i t r o g e n was a v a i l a b l e . The p o r t i o n o f o r g a n i c n i t r o g e n a v a i l a b l e f o r b a c t e r i a l a s s i m i l a t i o n v a r i e d w i d e l y , depending on t h e n a t u r e o f t h e waste. 2-3-2 Phosphorus Requirement The e f f e c t o f phosphorus on an a c t i v a t e d s l u d g e system was s t u d i e d by G r e e nsberg e t a l (21). They o b s e r v e d t h e growth o f s l u d g e s i n a s y n t h e t i c s u b s t r a t e , c o n t a i n i n g v a r y i n g amounts o f phosphorus. They came t o t h e f o l l o w i n g c o n c l u s i o n s : 1) Phosphorus d e f i c i e n c i e s caused a marked change i n the p h y s i c a l and c h e m i c a l c h a r a c t e r i s t i c s o f t h e mixed l i q u o r s o l i d s . A t e n d e ncy, f o r p h o s p h o r u s - d e f i c i e n t systems t o produce s l u d g e h a v i n g poor s e t t l i n g c h a r a c t e r i s t i c s , was most s i g n i f i c a n t . 2) When phosphorus was p r e s e n t i n s u b - o p t i m a l c o n c e n t r a t i o n s , the growth o f t h e s l u d g e s o l i d s was r e t a r d e d and t h e r a t e o f BOD^ removal was reduced. 3) A d e f i c i e n c y o f phosphorus r e s u l t e d i n a re d u c e d n i t r o g e n u t i l i z a t i o n by m i c r o - o r g a n i s m s . 4) The minimum r e q u i r e m e n t was 0.44 kg o f phosphorus p e r 100 kg o f BOD removed. 5 H a t t i n g h (22) i n v e s t i g a t e d the e f f e c t o f n i t r o g e n and phosphorus on t h e n u t r i t i o n a l s t a t e o f m i c r o - o r g a n i s m s i n , and the s e t t l i n g c h a r a c t e r i s t i c s o f , a c t i v a t e d s l u d g e . The f o l l o w i n g c o n c l u s i o n s were made: 1) To produce an a c t i v a t e d s l u d g e w i t h a t l e a s t 7% n i t r o g e n and 1.4% phosphorus, the BOD^/N/P.ratio s h o u l d not be l e s s than 100/4.35/0.595 2) The phosphorus r e q u i r e m e n t o f t h e micro-organisms i n c r e a s e d l o g a r i t h m i c a l l y w i t h , and depended on, the q u a n t i t i e s o f n i t r o g e n consumed. 3) B u l k i n g o f t h e s l u d g e o c c u r r e d o n l y when t h e BOD^ a p p l i e d /N/P r a t i o was l e s s t h a n 100/4.55/0.595. B u l k i n g was most s e v e r e when the r a t i o was below 100/2.7/0.238. 4) No marked d i f f e r e n c e s i n the c o m p o s i t i o n o f e i t h e r the p r o t o z o a l or b a c t e r i a p o p u l a t i o n s were o b s e r v e d , over t h e range o f n u t r i e n t l e v e l s i n v e s t i g a t e d . 2-3-3 N u t r i e n t Requirements as a F u n c t i o n o f Sludge Age I t has been proposed t h a t t h e n u t r i e n t r e q u i r e m e n t f o r a system i s a f u n c t i o n o f t h e s l u d g e age. S h e r r a r d and Shr o e d e r (23) used a f o o d p r o c e s s i n g wastewater t o d e v e l o p a r e l a t i o n s h i p between s l u d g e age and the n u t r i e n t r e q u i r e m e n t . S i k e s and Nieminen (24) e s t a b l i s h e d the same b a s i c r e l a t i o n s h i p u s i n g K r a f t - m i l l e f f l u e n t . F i g u r e 1 shows the r e s u l t s o f t h e two s t u d i e s . S e v e r a l c o n c l u s i o n s can be o b t a i n e d from t h e s e s t u d i e s : 1) A BODc/N/P r a t i o o f 100/5/1 i s u s e f u l o n l y a t a low 5 s l u d g e age o f 3 days. 2) A BOD /N/P r a t i o o f 100/2.5/0.5 would be a c c e p t a b l e a t a 5 s l u d g e age o f 20 days. 3) A l t h o u g h the r a t i o o f BOD /N and BOD/P d e c r e a s e s w i t h 5 5 slu d g e age, the N/P r a t i o remains c o n s t a n t a t 5/1. 2-4 L e a c h a t e Treatment Systems C h i a n and DeWalle (4) have p u t t o g e t h e r a comprehensive paper on s a n i t a r y l a n d f i l l l e a c h a t e s and t h e i r t r e a t m e n t . T h i s r e v i e w o f a r t i c l e s g i v e s a b e t t e r i n s i g h t i n t o b o t h the ex p e c t e d c h a r a c t e r i s t i c s o f l e a c h a t e s and t h e b e s t mode o f tr e a t m e n t . In g e n e r a l , t h e a c t i v a t e d s l u d g e and a e r a t e d l a g o o n systems have s u c c e s s f u l l y been used t o t r e a t l e a c h a t e s w i t h h i g h o r g a n i c c o n t e n t . The BOD/COD r a t i o o f b i o l o g i c a l l y - t r e a t e d l e a c h a t e ranged from 0.45 t o 0.81,which i n d i c a t e s t h a t the wastewater i s from a r e l a t i v e l y young l a n d f i l l . In l a n d f i l l s i t e s g r e a t e r than 10 y e a r s o l d , the BOD/COD r a t i o i n t h e l e a c h a t e was found t o drop below o . l . T h i s type o f l e a c h a t e was most e f f e c t i v e l y t r e a t e d by p h y s i c a l - c h e m i c a l p r o c e s s e s . x - SHERRARD a SCHR0EDER(23) o - SIKES S NIEMINEM (24) FIGURE l : NITROGEN AND PHOSPHORUS REQUIREfENT FOR ACTIVATED SLUDGE (23,24) Cook and F o r e e (25) s t u d i e d t h e a e r o b i c b i o s t a b i l i z a t i o n o f l e a c h a t e , u s i n g a c o m p l e t e l y - m i x e d extended a e r a t i o n system w i t h no r e c y c l e . The d e s i g n parameter used was th e v o l u m e t r i c o r g a n i c l o a d i n g , based on kg. COD/DAY/cubic meter. S i x r e a c t o r s were o p e r a t e d under v a r i o u s o r g a n i c l o a d i n g s , n u t r i e n t l o a d i n g s and pH c o n d i t i o n s . The l e a c h a t e used was o f "medium" s t r e n g t h , w i t h a BOD,, e q u a l t o 7100 mg/L, a B0D 5/N/P r a t i o o f 100/3.94/0.18 and a BOD /COD r a t i o o f 0.45. The r e a c t o r s w i t h 2-day and 5-day s l u d g e ages f a i l e d . The minimum t h e o r e t i c a l d e t e n t i o n time (sludge age) was c a l c u l a t e d t o be 5.3 days. A l l o f t h e r e a c t o r s w i t h a 10-day s l u d g e age removed a t l e a s t 97.6% o f t h e COD. I t was c o n c l u d e d t h a t pH c o n t r o l and n u t r i e n t a d d i t i o n d i d not s i g n i f i c a n t l y improve the t r e a t m e n t e f f i c i e n c y . The s l u d g e had v e r y good s e t t i n g p r o p e r t i e s and t h i s r e s u l t e d i n a low s u s p e n d e d - s o l i d l e v e l i n t h e e f f l u e n t . The m e t a l - r e m o v a l e f f i c i e n c y had mixed r e s u l t s . The t h r e e m e t a l s s t u d i e d showed the f o l l o w i n g r e d u c t i o n s : Iron-96%, Calcium-97%, and Magnesium-18%. The h i g h removal f o r i r o n and c a l c i u m was a t t r i b u t e d t o c h e m i c a l p r e c i p i t a t i o n , which o c c u r r e d a t the h i g h pH ( r a n g i n g from 7.6 t o 8.4) l e v e l found i n t h e s e r e a c t o r s . The m i c r o b i a l p o p u l a t i o n i n d i c a t e d t h a t a h i g h l y s t a b i l i z e d m i c r o b i mass e x i s t e d i n a l l o f t h e u n i t s w i t h a 10-day r e t e n t i o n time. The r e a c t o r s w i t h o u t n u t r i e n t a d d i t i o n had a l a r g e r f u n g i p o p u l a t i o n t h a n the o t h e r r e a c t o r s , but t h e s e u n i t s s t i l l o p e r a t e d e f f e c t i v e l y . B o y l e and Ham (26) i n v e s t i g a t e d the combined tre a t m e n t o f l a n d f i l l l e a c h a t e w i t h domestic sewage. The a u t h o r s examined the e f f e c t s o f l e a c h a t e a d d i t i o n s t o d o m e s t i c sewage on the performance o f an a c t i v a t e d s l u d g e system. The leachate had a BOD5 o f 8790 mg/L. The f r a c t i o n o f l e a c h a t e t o d o m e s t i c sewage was v a r i e d from 0 t o 20 per c e n t , on a volume b a s i s . No m e t a l o r n u t r i e n t a n a l y s i s was done i n t h i s l a b o r a t o r y s t u d y . } T a b l e V shows the e f f e c t o f t h i s l e a c h a t e a d d i t i o n . The e f f l u e n t q u a l i t y was not s i g n i f i c a n t l y e f f e c t e d up t o 5 per c e n t l e a c h a t e a d d i t i o n , o r 0.4 kg B0D5/DAY/cubic meter. The mixed-l i q u o r suspended s o l i d s were h e l d c o n s t a n t a t 2500 mg/L. The d a i l y s o l i d s p r o d u c t i o n i n c r e a s e d w i t h the i n c r e a s e d . c o n c e n t r a t i o n o f l e a c h a t e i n t h e f e e d . Thus, the s l u d g e age d e c r e a s e d w i t h an i n c r e a s e d l e a c h a t e l o a d i n g ; the r e a c t o r s w i t h up t o 5% l e a c h a t e f e e d had s l u d g e ages of over 20 days. The r e a c t o r s w i t h 10% l e a c h a t e f e e d o r g r e a t e r had a s l u d g e age o f l e s s t h a n 11 days. 19 TABLE V (26) EFFECTS OF LEACHATE ADDITION TO A DOMESTIC SEWAGE TREATMENT PLANT UNIT LEACHATE (%V/V) COD EFFLUENT (mg/L) % INCREASE IN COD OVER SEWAGE EFFLUENT 0 2 UPTAKE OF MIXED LIQUOR (mg/hr/gVSS) SLUDGE' , VOLUME INDEX S.V.I. t SLUDGE AGE (DAYS) A - l 0 30 — 24.5 49 1 J J 45 A-2 24 0 25.6 62 | 34 A-3 2 31 0 43.3 69 } 1 25 '• i : 1 2 1 \ A-4 ! 5 38 26.4 83. 5 100 : ! A-5 i 10 59 , 96.8 132.0 166 i i i » 1 1 j A-6 i i 20 113 276 230.0 526 ! ! Thus, t h e Bo y l e and Ham (26) study showed t h a t , i f more than 5% l e a c h a t e was added t o t h e r e a c t o r , t h e r e was a s u b s t a n t i a l i n c r e a s e i n s o l i d s p r o d u c t i o n and t h e m i x e d - l i q u o r oxygen uptake r a t e . A l s o , t h e s o l i d - l i q u i d s e p a r a t i o n became p o o r e r . Upadhyaya and Quenti n (27) have done a p i l o t p l a n t s t u d y , t r e a t i n g t h e n a t u r a l l y o c c u r r i n g l e a c h a t e from t h e Due West l a n d f i l l , i n N a s h v i l l e , Tennessee. A l e a c h a t e c o l l e c t i o n and t r e a t m e n t p l a n t was d e s i g n e d , based on b e n c h - s c a l e t r e a t a b i l i t y s t u d i e s . The t r e a t m e n t system i n v e s t i g a t e d was an a e r a t e d lagoon w i t h no r e c y c l e . The l e a c h a t e had a BOD 5 o f o n l y 219 mg/L. The n u t r i e n t l o a d i n g (BOD5/N/P) was 100/36/0.25. The experiment used sludge.ages o f 1.5, 3.8, and 7 days. A l l o f t h e u n i t s a c h i e v e d 85%+ B O D 5 removal. The h i g h t r e a t m e n t e f f i c i e n c y , a t such low s l u d g e ages, may be accounted f o r by t h e low i n i t i a l B O D 5 l e v e l s . U l o t h (8) s t u d i e d t h e e f f e c t o f d e t e n t i o n time on a e r o b i c t r e a t m e n t o f h i g h - s t r e n g t h l e a c h a t e . Emphasis was p l a c e d on d e t e r m i n i n g t h e d i s t r i b u t i o n o f m e t a l s i n t h e r e a c t o r . The l e a c h a t e used i n t h e stud y had a BOD5 o f 35,750 mg/L and COD = 48,000 mg/L, w i t h v a r y i n g l e v e l s o f m e t a l s . An extended a e r a t i o n system, w i t h o u t r e c y c l e , was used as t h e t r e a t m e n t method. N u t r i e n t s were added i n e x c e s s and t h e pH was n o t c o n t r o l l e d . The f o l l o w i n g c o n c l u s i o n s r e s u l t e d from t h i s s t u d y : 1) A e r o b i c b i o s t a b i l i z a t i o n i s an e f f e c t i v e means o f t r e a t i n g a , h i g h - s t r e n g t h , l a n d f i l l l e a c h a t e . By u s i n g a v e r y h i g h c o n c e n t r a t i o n o f m i x e d - l i q u o r v o l a t i l e s o l i d s (8000 t o 16000 mg/L), s t a b l e r e a c t o r o p e r a t i o n was e s t a b l i s h e d a t d e t e n t i o n t i m e s as s h o r t as 10 days, p r o v i d e d t h e f o o d t o m i c r o - o r g a n i s m r a t i o was kept below 0 . 2 2 kg B O D 5 a p p l i e d / k g VSS/DAY. At s l u d g e ages g r e a t e r than t e n days, t h e e f f l u e n t B O D 5 averaged o n l y 58.1 mg/L (99.8% r e m o v a l ) . 2) Most o f t h e m e t a l s i n the m i x e d - l i q u o r were removed by s e t t l i n g t h e b i o l o g i c a l f l o e . The m i x e d - l i q u o r pH was c o n s i s t e n t l y g r e a t e r than 8.5 and t h i s c e r t a i n l y a i d e d i n m e t a l removal. Aluminum, cadmium, chromium, i r o n , manganese, and z i n c were 95% removed. C a l c i u m , l e a d and n i c k e l were 85% removed. There was no i n d i c a t i o n o f a c u t e t o x i c i t y t o t h e mi c r o - o r g a n i s m s from the e s t a b l i s h e d m e t a l c o n c e n t r a t i o n s . The b i o l o g i c a l community became a c c l i m a t e d and r e s u l t e d i n a s t a b l e system. 3) A n a l y s i s o f the k i n e t i c parameters i n d i c a t e d t h a t t h e m e t a l s p r o b a b l y c o n t r i b u t e d t o the i n h i b i t i n g o f t h e b i o l o g i c a l a c t i v i t y o f the u n i t s . High m i x e d - l i q u o r v o l a t i l e suspended s o l i d s c o n c e n t r a t i o n s may thus be n e c e s s a r y t o o b t a i n a r e a s o n a b l e BOD5 r e d u c t i o n . 4) The n u t r i e n t l o a d i n g r a t i o was a t l e a s t 100/5/1. A n a l y s i s o f n u t r i e n t s i n t h e s e t t l e d e f f l u e n t i n d i c a t e d t h a t t h e n i t r o g e n and phosphorus a d d i t i o n s t o t h e l e a c h a t e f e e d were e x c e s s i v e . Thus, t h e n u t r i e n t l o a d i n g might be r educed, w i t h o u t a d v e r s e l y e f f e c t i n g t h e o v e r a l l t r e a t m e n t e f f i c i e n c y . An a e r o b i c m i c r o - b i o l o g i c a l t r e a t m e n t system, w i t h a l o n g s o l i d s r e t e n t i o n time (0 c ) , appears c a p a b l e of t r e a t i n g l a n d f i l l l e a c h a t e w i t h r e s p e c t t o B O D 5 , C O D and m e t a l r e m o v a l . The n u t r i e n t r e q u i r e m e n t s f o r such a t r e a t m e n t system might be s u b s t a n t i a l l y l e s s than the g e n e r a l l y a c c e p t e d d e s i g n l o a d i n g o f B O D t ^ / N / P = 100/5/1. CHAPTER 3 RESEARCH RATIONALE The m o n i t o r i n g and t r e a t m e n t o f l a n d f i l l l e a c h a t e 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 the l a s t few y e a r s . The C i v i l E n g i n e e r i n g Department a t the U n i v e r s i t y o f B r i t i s h Columbia has an a c t i v e program o f on-going r e s e a r c h i n t h i s a r e a . A e r o b i c and a n a e r o b i c d i g e s t i o n , p h y s i c a l - c h e m i c a l t r e a t m e n t and a c t i v a t e d carbon are some o f the t r e a t m e n t methods which have been i n v e s t i g a t e d r e c e n t l y . U l o t h (8) e s t a b l i s h e d t h a t a e r o b i c b i o s t a b i l i z a t i o n o f h i g h s t r e n g t h l e a c h a t e c o u l d be a v e r y e f f i c i e n t method o f t r e a t m e n t . The r e s u l t s o f h i s s t u d y were v e r y e n c o u r a g i n g and an attempt was made t o o p t i m i z e t h e system, w i t h r e s p e c t t o n u t r i e n t r e q u i r e m e n t s . I t was thus d e c i d e d t o i n v e s t i g a t e the e f f e c t s o f n u t r i e n t l o a d i n g on a e r o b i c t r e a t m e n t . There were s e v e r a l r e a s o n s f o r t h i s : 1) S i n c e l e a c h a t e s o f t e n had v e r y h i g h BOD^ c o n c e n t r a t i o n , c o n v e n t i o n a l d e s i g n c a l l e d f o r a h i g h n u t r i e n t c o n c e n t r a t i o n . T h i s meant p o s s i b l y a d d i n g l a r g e q u a n t i t i e s o f n i t r o g e n and phosphorus to t h e l e a c h a t e . 2) The c o s t o f n i t r o g e n and phosphorus s o u r c e s i s i n c r e a s i n g (24) (see F i g u r e 2 ) . FIGURE 2 (24) TRENDS IN NUTRIENT PRICES 5001 4004 I p 3001 U J o or I /-75%PH0SPH0RpC ACID 200 100 1971 1972 1973 1974 1975 - DATE-3) S t u d i e s (24,25) have shown t h a t the n u t r i e n t r e q u i r e m e n t i s a f u n t i o n o f s l u d g e age. Thus, i t may be p o s s i b l e t o have a h i g h degree o f t r e a t m e n t w i t h a r e d u c e d n u t r i e n t l o a d i n g , i f t h e s l u d g e age i s l o n g enough. 4) High n u t r i e n t l o a d i n g can r e s u l t i n n i t r o g e n and phosphorus c o n c e n t r a t i o n i n t h e t r e a t m e n t p l a n t e f f l u e n t , i n e x c ess o f t h e B.C. P o l l u t i o n C o n t r o l Board's O b j e c t i v e s (28). 5) High n i t r o g e n c o n c e n t r a t i o n i n a b i o l o g i c a l f l o e can cause a r i s i n g s l u d g e i n t h e c l a r i f i e r ( 7 ) . \ 6) No d a t a e x i s t s on the e f f e c t o f reduced n u t r i e n t l o a d i n g on m e t a l removal i n b i o l o g i c a l systems. 7) I f n u t r i e n t a d d i t i o n c o u l d be shown t o be u n n e c e s s a r y , t h e o p e r a t i o n o f a l e a c h a t e t r e a t m e n t p l a n t would be t h a t much s i m p l e r and cheaper. In a c t u a l p r a c t i c e , two modes o f t r e a t m e n t were f o r e s e e n . A t l a r g e l a n d f i l l s i t e s , t h e l e a c h a t e c o u l d be t r e a t e d on s i t e . In s m a l l e r l a n d f i l l s , the l e a c h a t e c o u l d be s t o r e d and p e r i o d i c a l l y t r a n s p o r t e d t o a c o n v e n t i o n a l domestic sewage t r e a t m e n t p l a n t . In b o t h c a s e s , t h e q u e s t i o n o f n u t r i e n t r e q u i r e m e n t s and t h e e f f e c t i v e n e s s o f m e t a l removal must be answered. Two experiments were thus p r o p o s e d : 1) A e r o b i c b i o s t a b i l i z a t i o n o f h i g h - s t r e n g t h l e a c h a t e , w i t h reduced n u t r i e n t l o a d i n g ( c o m p a r e d t o c o n v e n t i o n a l l o a d i n g o f 100/5/1) 2) A e r o b i c b i o s t a b i l i z a t i o n o f combined h i g h - s t r e n g t h l e a c h a t e and domestic sewage. The sewage was t o be used as a n a t u r a l s o u r c e o f n u t r i e n t s . In each experiment, t h e t r e a t m e n t e f f i c i e n c y was t o be m o n i t o r e d as a f u n c t i o n o f n u t r i e n t l o a d i n g . A l s o , an attempt would be made t o f o l l o w the change i n d i g e s t e r b e h a v o i r , caused by v a r y i n g t h e n u t r i e n t l o a d i n g , i . e . , f o l l o w i n g the b i o l o g i c a l k i n e t i c p arameters, K, Y, K^. A key f a c t o r would a l s o be t h e e f f i c i e n c y o f m e t a l r e m o v a l . I t was e x p e c t e d t h a t t h e m e t a l r e m o v a l e f f i c i e n c y m i g h t d e c r e a s e as t h e n u t r i e n t l o a d i n g d e c r e a s e d . B u t , i t was n o t known i f t h i s l o s s o f e f f i c i e n c y m i g h t be t h e r e s u l t o f m e t a b o l i c changes i n t h e m i c r o - o r g a n i s m s , o r t h e r e s u l t o f a p o o r s e t t l i n g f l o e . CHAPTER 4 SYSTEM DESIGN AND EXPERIMENTAL TECHNIQUE 4-1 P h y s i c a l D e s i g n A s i n g l e - s t a g e , b e n c h - s c a l e system was used f o r t h i s r e s e a r c h . U l o t h (8) demonstrated t h a t such a system was an e f f e c t i v e and s i m p l e method o f s t u d y i n g the b i o t r e a t a b i l i t y o f a wastewater. The r e a c t o r s were made from l a r g e g l a s s b o t t l e s . The bottom o f each b o t t l e was removed and the necks were f i t t e d w i t h l a r g e r u bber s t o p p e r s . The s t o p p e r s were s e c u r e d u s i n g s t a i n l e s s s t e e l w i r e but no w i r e was a l l o w e d i n s i d e t h e r e a c t o r s , thus p r e v e n t i n g any unknown a d d i t i o n s o f m e t a l t o the r e a c t o r s ' c o n t e n t . A porous g l a s s , c o a r s e - b u b b l e , a i r d i f f u s e r was f i t t e d i n t h e bottom o f each d i g e s t e r and t h e a i r was p r o v i d e d f o r each u n i t from t h e l a b o r a t o r y compressed a i r system. In o r d e r t o c o n t r o l any foaming and t o ensure adequate m i x i n g , a c o m b i n a t i o n o f a i r and m e c h a n i c a l m i x i n g was used. An a d j u s t a b l e clamp was p l a c e d on t h e a i r l i n e o f each r e a c t o r t o c o n t r o l the a i r f l o w r a t e and an e l e c t r i c a l l y d r i v e n s t i r r e r was p r o v i d e d i n each d i g e s t e r t o ensure u n i f o r m d i s t r i b u t i o n o f f o o d and m i c r o - organisms M i x i n g speed was s e t a p p r o x i m a t e l y e q u a l i n a l l d i g e s t e r s . The a i r f l o w r a t e s were a d j u s t e d t o m a i n t a i n a e r o b i c c o n d i t i o n s , w h i l e m i n i m i z i n g foaming. A s c h e m a t i c of t h r e e r e a c t o r s i s shown i n F i g u r e 3. ' E l e c t r i c motor Volumetric graduotion (on masking tape) P l a s t i c tubing Oil - f r e e o'tr 0 E l e c t r i c motor d r i v e n s t i r r e r . Porous , G l a s s , Coarse b u b b l e d i f fuser A d j u s t a b l e screw clamp R u b b e r stopper \1 } FIGURE 3: SCHEMATIC OF LABORATORY AEROBIC REACTORS To c o n t a i n any foam which might be produced, o n l y 4.5 l i t r e s o f m i x e d - l i q u o r was m a i n t a i n e d i n each r e a c t o r , thus a l l o w i n g f o r about 20 cm o f f r e e b o a r d . The worst foaming problems o c c u r e d d u r i n g the f i r s t few days o f s t a r t - u p , but even t h e n , the foaming was c o n t r o l l a b l e . The d i g e s t e r s were o p e r a t e d a t room temperature, which averaged about 20° C. Any s m a l l changes i n temperature were not o f c o n c e r n , as t h e y would not e f f e c t t h e b i o l o g i c a l p r o c e s s e s . The room temperature ranged from 18 t o 24°C. 4-2 Leachate and Sewage Sources and C h a r a c t e r i s t i c s The l e a c h a t e used i n t h i s s t u d y was g e n e r a t e d from l y s i m e t e r s , c o n s t r u c t e d a t t h e U n i v e r s i t y o f B r i t i s h Columbia, i n Vancouver, B.C. Research i s b e i n g done t o c h a r a c t e r i z e l a n d f i l l l e a c h a t e s and m o n i t o r v a r i a t i o n s i n t h e i r c o m p o s i t i o n w i t h time, r a i n f a l l r a t e , c o v e r m a t e r i a l and o t h e r parameters. D e t a i l s o f a t y p i c a l l y s i m e t e r a r e : 1) Dimensions 4.3 meters deep, 1.2 meters d i a m e t e r , 2) Cover m a t e r i a l 0.5 meters hog f u e l , 3) T o t a l w eight 1550 k g , 4) Depth o f garbage 2.5 m e t e r s , 5) D e n s i t y o f garbage b e f o r e f i n a l c o v e r 525 k g / c u b i c meter (wet), 6) R a i n f a l l r a t e 380 mm/year. 7) P e r c e n t a g e c o m p o s i t i o n o f garbage: Food waste 11.8% Garden waste 9.8% Paper p r o d u c t s 47.6% Cardboard 5.4% T e x t i l e s 3.6% Wood 4.6% M e t a l 8.7% G l a s s and c e r a m i c s 7.0% Ash, r o c k s , and d i r t 1.4% TOTAL - 99.9% L e a c h a t e from t h i s l y s i m e t e r was c o l l e c t e d weekly, r e t u r n e d o o t o t h e l a b o r a t o r y and s t o r e d a t 4 C. The 4 C. temperature has been found t o m i n i m i z e changes i n l e a c h a t e c o m p o s i t i o n . Samples were c o l l e c t e d over s e v e r a l weeks and combined t o produce a composite sample, which was s t o r e d i n 20 l i t r e p o l y e t h y l e n e b o t t l e s a t 4° C. Two composite samples were c o l l e c t e d . The f i r s t was used i n the "pure l e a c h a t e " experiment and f i v e months l a t e r , a n o t h e r sample was c o l l e c t e d f o r use i n the " c o m b i n a t i o n " experiment. The sewage sample was c o l l e c t e d weekly from t h e A n n a c i s I s l a n d Sewage Treatment P l a n t . The e f f l u e n t was c o l l e c t e d from t h e d i s c h a r g e o f t h e p r i m a r y c l a r i f i e r and s t o r e d a t 4° C. The c h a r a c t e r i s t i c s o f t h e f e e d samples a r e shown i n T a b l e V I . 30 TABLE VI COMPOSITION OF LEACHATES AND SEWAGE Le a c h a t e In Leac h a t e In Sewage Used In Parameter (mg/L) "Pure L e a c h a t e " Expt "Combination" Expt "Combination" Expt BOD 5 19,330 18,025 56 COD 30,410 28,830 124 T o t a l S o l i d s 15,850 19,940 176 V o l a t i l e S o l i d s 6,340 7,560 84 Suspended S o l i d s 990 1,290 47 A l k a l i n i t y 6,660 5,265 100 Aluminum 11.0 3.06 0.33 A r s e n i c 0.33 Boron 4.66 C a l c i u m 1,020 Cadmium 0.0716 0.344 0.0031 C h l o r i d e 732 Chromium 0.365 0.44 0.007 Copper 0.039 I r o n 960 750 0.694 Lead 0.167 0.106 0.0101 Magnesium 157 Manganese 34.8 20.5 0.099 TKN 616 560 137 N i c k e l 0.247 T o t a l Phosphorus 23 11.4 2.4 Potassium 540 Selenium 0.285 S u l p h a t e 280 S i l i c o n 37 Z i n c 49.5 71.0 0.0457 pH * 5.15 5.0 6.9 * Not i n m.g/L 4-3 pH C o n t r o l Based on the work o f U l o t h (.8) , i f was found t h a t , i f t h e pH was a d j u s t e d t o 7.0 a t t h e b e g i n n i n g o f t h e experiment and not c o n t r o l l e d a f t e r t h a t , t h e pH would r i s e t o 8.5 w i t h i n two days. Thus, i n t h i s s t u d y , t h e pH was not p u t under any s p e c i f i c c o n t r o l . 4-4 N u t r i e n t s The n i t r o g e n and phosphorus was v a r i e d i n each o f s i x r e a c t o r s . Ammonium c h l o r i d e (NH^Cl) was used as a n i t r o g e n s o u r c e and p o t a s s i u m phosphate monobasic (KH^PH^) was used as a phosphorus s o u r c e . The raw l e a c h a t e had a BOD5/N/P r a t i o o f 100/3.20/0.12. The n i t r o g e n s u p p l i e d by t h e l e a c h a t e was a p p r o x i m a t e l y 60% o f the recommended amount and t h i s l i m i t e d the range ' o v e r which t h e experiment c o u l d be s t u d i e d . No attempt was made t o lower t h e l e a c h a t e s ' n i t r o g e n c o n c e n t r a t i o n because removing t h e n i t r o g e n c o u l d have e f f e c t e d o t h e r c h a r a c t e r i s t i c s o f the l e a c h a t e . The phosphorus i n t h e l e a c h a t e was about 10% o f t h e recommended amount. T h i s a l l o w e d a wide range o f i n v e s t i g a t i o n . There was a problem o f p r e c i p i t a t i o n o c c u r i n g , when c o n c e n t r a t e d n u t r i e n t s o l u t i o n s were added t o the l e a c h a t e f e e d . To a v o i d t h i s s i t u a t i o n , the a p p r o p r i a t e amount o f t h e c o n c e n t r a t e d s t o c k n u t r i e n t s o l u t i o n s were added d i r e c t l y t o the m i x e d - l i q u o r each day. The n u t r i e n t l o a d i n g f o r each d i g e s t e r i s shown i n T a b l e V I I . The lower l i m i t s o f t h e BOD /N/P r a t i o were v e r y s i m i l a r i n b o t h 5 experi m e n t s , a l t h o u g h t h e a c t u a l c o n c e n t r a t i o n s o f n i t r o g e n and phosphorus were v e r y d i f f e r e n t . TABLE V I I NUTRIENT LOADINGS BOD 5 o f N i t r o g e n Phosphorus BOD./N/P R e a c t o r Feed (mg/L) Cone. (mg/D Cone. (mg/L) R a t i o "Pure L e a c h a t e " Experiment A ( l ) 19,330 973 214 100/5.03/1.11 B ( l ) 19,330 769 214 100/3.98/1.11 C ( l ) 19,330 616 214 100/3.19/1.11 D ( l ) 19,330 769 61.3 100/3.98/0.32 E d ) 19,330 769 23 100/3.98/0.12 F ( l ) 19,330 616 23 100/3.19/0.12 "Combination" Experiment A(2) 56 13.7 2.40 100/24.5/4.29 B(2) 236 19.2 2.49 100/8.12/1.06 C(2) 595 30.01 2.67 100/5.04/0.45 D(2) 1,134 46.48 2.94 100/4.10/0.26 E(2) 1,850 66.96 3.30 100/3.62/0.29 F(2) 3,650 123.0 4.20 100/3.62/0.12 4-5 "Pure L e a c h a t e " Experiment - Treatment o f L e a c h a t e w i t h Reduced N u t r i e n t L o a d i n g . The "Pure L e a c h a t e " experiment was performed i n two phases; an i n i t i a l a c c l i m a t i o n phase, f o l l o w e d by an extended r u n a t s t e a d y s t a t e . As l i t t l e as p o s s i b l e l i q u o r s o l i d s were removed d u r i n g t h e a c c l i m a t i o n phase, w h i l e t h e s t e a d y - s t a t e phase was o p e r a t e d on a draw and f i l l b a s i s . Based on the work done by U l o t h (8), a s l u d g e age o f 20 days was s e l e c t e d . T h i s s l u d g e age was e x p e c t e d t o r e s u l t i n s u c c e s s f u l t r e a t m e n t , i f the p r o p e r amount o f n u t r i e n t s were added. A c c l i m a t i o n Phase •» A sample o f s l u d g e from t h e secondary c l a r i f i e r o f t h e Mamquam Sewage Treatment P l a n t i n Squamish, B.C., was c o l l e c t e d . T h i s p l a n t i s a p a c k a g e - a c t i v a t e d s l u d g e system, which t r e a t s d o m e s t i c wastewater. In o r d e r t o m i n i m i z e any m e t a l c o n t r i b u t i o n from t h i s seed s l u d g e and t o p r o t e c t the seed from a shock l o a d , t h e r e a c t o r s were not f i l l e d t o volume a t f i r s t ( d a y 1 ) . I n s t e a d , 1.0 l i t r e o f water, 0.5 l i t r e s o f l e a c h a t e and 0.5 l i t r e s o f seed s l u d g e were combined. The pH was a d j u s t e d t o 7.0 and a e r a t i o n and m i x i n g s t a r t e d . The f i n a l l i q u i d volume i n each d i g e s t e r was 4.5 l i t r e s . With d e t e n t i o n time o f 20 days, t h e l o a d i n g r e q u i r e d was 0.225 l i t r e s o f l e a c h a t e p e r day. The l i q u i d volume a t s t a r t - u p was 2.0 l i t r e s . Thus ev e r y day f o r t h e remainder o f the s t u d y , 0.225 l i t r e s o f l e a c h a t e and an a p p r o p r i a t e n u t r i e n t l o a d were added t o the m i x e d - l i q u o r o f each d i g e s t e r . On t h e e l e v e n t h day o f o p e r a t i o n , t h e d i g e s t e r volumes r e a c h e d 4.5 l i t r e s . In o r d e r t o i n c r e a s e t h e m i x e d - l i q u o r s o l i d s c o n c e n t r a t i o n i n the d i g e s t e r s , the m i x e d - l i q u o r was a l l o w e d t o s e t t l e each day. The a e r a t i o n and m i x i n g were stopped f o r one hour. Then 0.225 l i t r e s o f t h e c l a r i f i e d e f f l u e n t was removed and 0.225 l i t r e s o f l e a c h a t e and n u t r i e n t s were added. T h i s p r o c e d u r e was f o l l o w e d f o r 25 days between day 11 and day 36 Steady S t a t e Phase - A t day 36, t h e m i x e d - l i q u o r , suspended s o l i d s l e v e l was c o n s i d e r e d h i g h enough, based on e s t i m a t e s from the U l o t h ( 8 ) s t u d y . The p r o c e d u r e was then changed t o a s t e a d y - s t a t e o p e r a t i o n . Each day, 0.225 l i t r e s o f m i x e d - l i q u o r was drawn o f f and an e q u a l volume o f l e a c h a t e and n u t r i e n t s was added. T h i s p r o c e d u r e was c o n t i n u e d f o r 48 days u n t i l t h e end o f experiment number one. D i g e s t e r O p e r a t i o n - E v e r y t w e n t y - f o u r hours, t h e water l o s t by e v a p o r a t i o n was r e p l a c e d by d i s t i l l e d water. The s i d e s o f t h e d i g e s t e r s and t h e s t i r r e r were s c r a p e d , t o remove a l l t h e a d h e r i n g m i c r o - o r g a n i s m s and r e t u r n t h e s o l i d s t o t h e m i x e d - l i q u o r . The pH , temperature and d i s s o l v e d oxygen l e v e l i n t h e m i x e d - l i q u o r were m o n i t o r e d d a i l y . E v e r y seven days, t h e withdrawn m i x e d - l i q u o r was a l l o w e d t o s e t t l e f o r 30 minutes and a c l a r i f i e d sample c o l l e c t e d . The m i x e d - l i q u o r and c l a r i f i e d e f f l u e n t were a n a l y z e d f o r B O D 5 , COD, "VS'S,- t o t a l K j e l d a h l n i t r o g e n and t o t a l phosphorus (29) . D u r i n g t h e l a s t t h r e e days o f th e experiment (days 81 t o 84), o t h e withdrawn mixed^-liquor was c o l l e c t e d and s t o r e d a t 4 C. On t h e f i n a l day, a 350 ml. sample o f m i x e d - l i q u o r was t a k e n and combined w i t h t h e m i x e d - l i q u o r a l r e a d y c o l l e c t e d . The r e m a i n i n g m i x e d - l i q u o r was a l l o w e d t o s e t t l e f o r two and o n e - h a l f hours and a 1250 ml. sample of t h e c l a r i f i e d e f f l u e n t was t a k e n . F i n a l l y , t h e s e t t l e d s l u d g e was c e n t r i f u g e d a t 2000 RPM, f o r 15 minutes and t h e s u p e r n a t a n t was f i l t e r e d t h r o u g h a Whatman No. 4 f i l t e r . A l l t h e samples were d i g e s t e d and a n a l y z e d f o r m e t a l s f o l l o w i n g t h e recommended E P A p r o c e d u r e (30). 4-6 "Combination" Experiment - Combined Treatment o f Leachate and Domestic Sewage. The "Combination" experiment was o p e r a t e d i n the same manner as the f i r s t experiment. The same r e a c t o r s and s l u d g e age were used f o r b o t h e x p e r i m e n t s . The main d i f f e r e n c e s were the s o u r c e o f the seed, the l e n g t h o f t h e a c c l i m a t i o n p e r i o d , and the c o m p o s i t i o n o f the f e e d . A c c l i m a t i o n Phase - The seed f o r experiment number two was t h e m i x e d - l i q u o r from r e a c t o r A ( l ) o f "Pure L e a c h a t e " experiment. The seed thus came from a w e l l - a c c l i m a t e d system and was e x p e c t e d t o be a b l e t o handle a shock l o a d e f f e c t i v e l y . Each r e a c t o r was f i l l e d up t o a t o t a l o f 4.5 l i t r e s , w i t h t h e a p p r o p r i a t e m i x t u r e s o f l e a c h a t e and sewage. (See T a b l e V I I I ) . TABLE V I I I LEACHATE LOADING FOR "COMBINATION" EXPERIMENT Reactor No. A(2) B(2) C(2) D(2) E(2) F(2) % L eachate ( V o l . o f Leachate! 0 1 3 6 10 20 ( T o t a l Volume) A s m a l l volume (20 mis. o f r e a c t o r A ( l ) m i x e d - l i q u o r ) of seed was added t o each r e a c t o r . The pH was a d j u s t e d t o 7.0, and t h e a e r a t i o n and m i x i n g s t a r t e d (day 1 ) . D u r i n g the a c c l i m a t i o n p e r i o d , the m i x i n g and a e r a t i o n was stopped f o r one hour, 0.225 l i t r e s o f c l a r i f i e d e f f l u e n t was removed, and 0.225 l i t r e s o f f e e d was added. T h i s p r o c e d u r e a l l o w e d the mixed-l i q u o r s o l i d s t o b u i l d up r a p i d l y . R e a c t o r s numbered A ( 2 ) , B ( 2 ) , and C(2) were o p e r a t e d i n t h i s manner u n t i l day 7. However, r e a c t o r s D(2), E(2) and F(2) were o p e r a t e d i n th e a c c l i m a t i o n mode u n t i l day 14, because o f the h i g h e r l o a d i n g r a t e s . S t e a d y - S t a t e Phase - A f t e r t h e a c c l i m a t i o n phase, the r e a c t o r s were o p e r a t e d i n th e s t e a d y - s t a t e mode, a t a draw and f i l l r a t e o f 0.225 L/day. T h i s p r o c e d u r e was f o l l o w e d u n t i l t h e experiment ended on day 48. R e a c t o r O p e r a t i o n - The d a i l y maintenance, weekly m o n i t o r i n g , and f i n a l sampling p r o c e d u r e was the same as i n the "Pure L e a c h a t e " experiment. CHAPTER 5 t DISCUSSION OF RESULTS 5-1 -"Pure L e a c h a t e " Experiment The purpose o f t h i s experiment was t o i n v e s t i g a t e t h e e f f e c t s o f n u t r i e n t l o a d i n g on the a e r o b i c t r e a t m e n t o f h i g h s t r e n g t h l e a c h a t e . In r e a c t o r s A ( l ) , B ( l ) and C ( l ) , (see T a b l e V I I ) , t h e phosphorus l e v e l was h e l d c o n s t a n t a t t h e recommended BOD /P r a t i o o f 100/1.11. 5 The n i t r o g e n l e v e l was d e c r e a s e d from a BOD^/N r a t i o o f 100/5.03 t o 100/3.19. Thus, r e a c t o r s A (1) , B (1) and C (1) show t h e e f f e c t o f reduced n i t r o g e n L o a d i n g . In r e a c t o r s B ( l ) , D ( l ) and E ( l ) , t h e n i t r o g e n l e v e l was h e l d a t a r e l a t i v e l y h i g h l e v e l , w i t h a B O D 5/N r a t i o o f 100/3.98. The phosphorus l e v e l was d e c r e a s e d from a B0D../P r a t i o o f 100/1.11 t o 5 100/0.12. Thus, r e a c t o r s B ( l ) , D ( l ) and E ( l ) show t h e e f f e c t o f reduced phosphorus l o a d i n g . R e a c t o r F ( l ) was f e d l e a c h a t e w i t h no n u t r i e n t a d d i t i o n and thus showed t h e e f f e c t o f low n i t r o g e n and phosphorus l o a d i n g . R e a c t o r A ( l ) had a n u t r i e n t l o a d i n g recommended i n most handbooks o f b i o l o g i c a l t r e a t m e n t p l a n t d e s i g n ( 7 ) . The r e s u l t s o f the experiments a r e t a b u l a t e d i n T a b l e IX-mixed l i q u o r c h a r a c t e r i s t i c s ; T a b l e X - s e t t l e d e f f l u e n t c h a r a c t e r i s t i c s ; and T a b l e X l - f i l t e r e d e f f l u e n t c h a r a c t e r i s t i c s . 5-1-1 BOD 5 Mixed L i q u o r BOD,, i s an i m p o r t a n t parameter i n measuring t h e e f f e c t i v e n e s s o f a t r e a t m e n t system. U l o t h (8) has demonstrated t h a t t h e l e a c h a t e and m i x e d - l i q u o r BOD^ t e s t s r e s u l t s were dependent on t h e d i l u t i o n f a c t o r i n t h e BOD b o t t l e . In o r d e r t o be c o n s i s t e n t , t h e TABLE IX MIXED LIQUOR CHARACTERISTICS "PURE LEACAHTE" EXPERIMENT C h a r a c t e r i s t i c s ( a l l , e x c e p t pH, mg/iL) L e a c h a t e Feed Reactor A ( l ) R e a c t o r B ( l ) R e a c t o r \ C ( l ) ! I Reactor D ( l ) R eactor E ( l ) R eactor F ( l ) BOD 5 COD 19,3.30 30,410 2970 7510 3290 8130 2870 1 9340 | 3290 7900 2220 7270 1890 3100 T o t a l S o l i d s T o t a l V o l a t i l e S o l i d s T o t a l Suspended 15,850 6,340 990 14210 7390 12980 ' 13990 7270 12640 15100 ! 8160 j 13550 | 13640 7370 13260 12820 6920 117 30 12 360 6550 10610 S o l i d s V o l a t i l e Suspended 387 8130 7850 8280 ; 7780 7050 6540 S o l i d s A c i d i t y A l k a l i n i t y pH 6660 5.15 0 1540 8. 30 0 3200 8.60 0 3400 8.90 0 3500 8.50 0 3550 8.70 0 4050 8.70 Aluminum Cadmium Chromium Ir o n Lead Manganese T o t a l K j e l d a h l N i t r o g e r T o t a l Phosphorus Z i n c 11.0 0.0716 0. 365 960 0.167 34.8 1 -1 ! 49.5 13.6 0.0955 0.68 1150 0.243 43.2 596 1 198 1 66.9 i 12.6 0.0836 0.64 1060 0.213 35.9 599 230 61.0 12.3 0.0836 2 . 32 1040 0. 228 35.6 504 271 59.4 12.6 0.0716 0.64 1040 0.228 35.6 504 47 61.0 11.8 0.0716 0.59 980 0.228 33.1 330 22 56.2 10.8 0.0716 0.58 900 0.182 30.2 459 18 51.5 T K.N. i n Feed j 616 | 973 7 69 616 7 69 769 616 T P . i n fe e d BOD5/N/P ; 23 214 100 5.034 214 100 3.978 214 100 3.187 61. 3 100 3.978 23 • 100 3.978 23 100 3.187 i 1.107 I 1.107 1 1.107 | 0.3171 0.1190 i 0.1190 TABLE X SETTLED EFFLUENT CHARACTERISTICS "PURE LEACHATE" EXPERIMENT C h a r a c t e r i s t i c s ( a l l , except pH, i n mg/L)  BOD 5 COD T o t a l S o l i d s T o t a l V o l a t i l e S o l i d s T o t a l Suspended S o l i d ^ V o l a t i l e Suspended S o l i d s A l k a l i n i t y pH Aluminum Cadmium Chromium Iro n Lead Manganese TKN TP Z i n c L e a c h a t e Feed 19330 30410 15850 6340 990 387 6660 5.15 11.0 0.0716 0.365 960 0.167 34.8 V a r i e s V a r i e s 49.5 R e a c t o r A ( l ) R e a c t o r B ( l ) [Reactor C ( l ) 82 487 3980 792 380 293 420 8.30 0.613 0.00186) 0.050 2 0.0106 0.641 28.0 10 1.31 25 55 448 3560 7 32 133 105 870 8.60 1 15 8 0.275 0.00093| 0.033 9.72 0.0061 03 1 5 0.630 [Reactor D ( l ) (Reactor E ( l ) [Reactor F ( l ) 36 409 3210 676 47 40 1240 8.90 0.319 I 0.00047J 0.035 | 4.27 0.0030 0.454 11.2 9.0 0.295 300 2476 4870 2068 1805 1568 800 8.50 0.978 ! 0.00558J 0.103 i 27.3 j 0.0228 | 3.36 ! 109.2 j 10.4 2 .10 1430 1540 3880 1348 245 230 950 8.70 0.288 0.00186| 0.040 j 13.5 i 0.0046 j 1.04 j 149.3 : 17.0 0.726 ; 560 686 3340 1036 160 158 1440 8.70 0.188 0.00093J 0.033 6.73 0.0152 0.953 82.1 1.0 0.543 P.C.B. O b j e c t i v e (2i 45 6.5 -8.5 0.5 0.005 0.10 0. 3 0.05 0.05 15.0 4.5 0.5 10 TABLE XI FILTERED EFFLUENT CHARACTERISTICS "PURE LEACHATE" EXPERIMENT C h a r a c t e r i s t i c ( a l l , Leachate R e a c t o r Reactor R e a c t o r Reactor Reactor R e a c t o r P.C.B. <28) ex c e p t pH, i n mq/L) Feed A ( l ) B ( l ) C ( l ) D ( l ) E ( l ) F ( l ) O b j e c t i v e BOD 5 19330 44 26 14 28 85 56 45 COD 30410 273 335 476 585 1162 569 T o t a l S o l i d s 15850 3650 3330 3290 3280 3630 3180 T o t a l V o l a t i l e 6340 572 596 852' 748 1016 868 s o l i d s T o t a l Suspended 990 - - — — _ — S o l i d s V o l a t i l e Suspended 387 - - - — — — S o l i d s A l k a l i n i t y 6660 400 850 1250 720 965 1410 pH 5.15 8. 30 8.60 8.90 8.50 8.70 8.70 6.5 -8.5 Aluminum 11.0 0.019 0.088 0.126 0.071 0.121 0.075 0. 50 j Cadmium 0.0716 0.00064 0.00023 0.00035| 0.00053 0.00035 0.00053 0.005 Chromium 0.365 0.017 0.020 0.039 0.028 0.037 0.032 0.10 I r o n ! 960 0.256 0.161 0.509 1.11 3.98 0.554 0. 30 I Lead j 0.167 0.0014 0.0010 0.0000 0.0007 0.0133 0.000 0.05 Manganese 34.8 0.526 0.390 0.493 1.16 0.920 0.683 0.05 1 TKN V a r i e s 8.2 10.2 10.05 25.2 129 74.2 ; 15.0 ; TP V a r i e s 1.4 0.00 0.00 1.25 0.00 0.00 ! 4 - 5 j Z i n c 49.5 0.125 0.128 0.159 0. 227 0.420 0.251 j 0.5 it* o the l e a c h a t e d i l u t i o n f a c t o r was h e l d a t 5000 and t h e m i x e d - l i q u o r d i l u t i o n f a c t o r h e l d a t 1000. The r e d u c t i o n i n n i t r o g e n l o a d i n g had l i t t l e e f f e c t on t h e mixed-l i o u o r BOD_. However, when t h e phosphorus l e v e l (BOD /P) was drooped ^ 5 " b from 100/1.11 t o 100/0.12, t h e mixed l i q u o r B0D 5 dropped from 3000 mg/L t o 2000 mg/L. S e t t l e d E f f l u e n t - The s e t t l e d e f f l u e n t d a t a i s v e r y i m p o r t a n t because i t i n d i c a t e s what q u a l i t y o f water w i l l be d i s c h a r g e d from the tre a t m e n t system. Such an e f f l u e n t s h o u l d meet t h e B.C. P o l l u t i o n C o n t r o l Branch O b j e c t i v e s (28) . A d e c r e a s e i n n i t r o g e n l o a d i n g caused a d e c r e a s e i n s e t t l e d e f f l u e n t BOD^. The o n l y d i g e s t e r which met the P.C.B. L e v e l A o b j e c t i v e s o f 45 mg/L had no n i t r o g e n added t o t h e f e e d . A drop i n t h e BOD^/N r a t i o from 100/5.03 t o 100/3.19 r e s u l t e d i n a drop i n s e t t l e d e f f l u e n t BOD^ from 82 t o 36 mg/L. A l t h o u g h r e a c t o r s A ( l ) and B ( l ) d i d not meet the P.C.B. O b j e c t i v e s they s t i l l removed 99.6%+ o f t h e BOD,.. The BOD^/P r a t i o had a s i g n i f i c a n t e f f e c t on t h e s e t t l e d e f f l u e n t BOD . When t h e BOD /P r a t i o was reduced from 100/1.11 t o 100/0.12, the 5 5 BOD^ i n c r e a s e d from 55 mg/L t o 1460 mg/L. (See F i g u r e 4.) The i n c r e a s e i n BOD,, w i t h a d e c r e a s e i n n u t r i e n t s i s caused i n p a r t by a d e t e r i o r a t i o n o f t h e s o l i d l i q u i d s e p a r a t i o n phase, as w i l l be shown i n t h e d i s c u s s i o n o f t h e suspended s o l i d s r e s u l t s . F i l t e r e d E f f l u e n t - The tr e a t m e n t o f a waste t a k e s p l a c e i n two phases: f i r s t , t h e a d s o r p t i o n and uptake o f m a t e r i a l s i n t o FIGURE k: EFFECT OF PHOSPHORUS LOADING ON BOD and on t o t h e b i o l o g i c a l f l o e , and second, t h e removal o f t h e b i o l o g i c a l f l o e from t h e l i q u i d phase. By m o n i t o r i n g t h e f i l t e r e d e f f l u e n t d a t a , t h e e f f e c t i v e n e s s o f t h e two phases can be i n v e s t i g a t e d . I f a t r e a t m e n t p l a n t i s working p r o p e r l y , t h e r e s h o u l d be l i t t l e d i f f e r e n c e between t h e q u a l i t y o f t h e s e t t l e d e f f l u e n t and t h e f i l t e r e d e f f l u e n t . I f a l a r g e d i f f e r e n c e does e x i s t , i t i s an i n d i c a t i o n o f l e s s t h a n i d e a l o p e r a t i o n o f t h e s o l i d - l i q u i d s e p a r a t i o n phase. When t h e phosphorus l o a d i n g was m a i n t a i n e d a t 100/1.11, a p p r o x i m a t e l y 45% o f t h e B O D 5 i n t h e s e t t l e d e f f l u e n t was t i e d up i n b i o l o g i c a l s o l i d s . The f i l t e r e d e f f l u e n t s , i n t h e s e c a s e s , a l l met t h e P.C.B. o b j e c t i v e s . However, a t lower phosphorus l o a d i n g s , 90% o f t h e B O D 5 i n t h e s e t t l e d e f f l u e n t was due t o the b i o l o g i c a l s o l i d s . T h i s means t h a t m i c r o - o r g a n i s m s were e f f e c t i v e l y a b s o r b i n g the B O D 5 but t h e b i o - f l o c was not b e i n g removed from the l i q u i d phase. (See F i g u r e 4) 5-1-2 Suspended S o l i d s Mixed L i q u o r - T h e m i x e d - l i q u o r v o l a t i l e suspended s o l i d s (MLVSS) was used as a measure o f mass o f organisms p r e s e n t . The MLVSS was m o n i t o r e d on a weekly b a s i s . When t h e MLVSS l e v e l remained c o n s t a n t o v e r a p e r i o d o f weeks, i t was assumed t h a t t h e d i g e s t e r had reached s t e a d y - s t a t e . F i g u r e 5 shows t h e development o f MLVSS l e v e l s i n the "Pure L e a c h a t e " experiment. The n i t r o g e n l o a d i n g had l i t t l e e f f e c t on MLVSS l e v e l s . However, when t h e phosphorus l o a d i n g was reduced, t h e MLVSS l e v e l dropped from 7850 mg/L t o 7050 mg/L. The l o w e s t l e v e l o f n i t r o g e n l o a d i n g used i n t h i s experiment was n o t low enough t o l i m i t growth o f m i c r o - o r g a n i s m . However, the l o w e s t phosphorus l o a d i n g 1 0 , 0 0 0 DAYS FROM START UP FIGURE 5: MIXED LIQUOR VOLATILE SUSPENDED SOLIDS VERSUS TI Ml* FROM START-UP FOR "PURE LEACHATE" EXPERIMENT 45 was c a p a b l e o f l i m i t i n g m i c r o b i a l growth. --Set t l e d E f f l u e n t - ~. The t o t a l suspended s o l i d s v a l u e i n t h e s e t t l e d e f f l u e n t was a c r i t i c a l f a c t o r i n d e t e r m i n i n g t h e e f f e c t i v e n e s s o f a p a r t i c u l a r t r e a t m e n t system. There was a l a r g e amount o f p o l l u t a n t s absorbed on t o the b i o l o g i c a l f l o e ' I f t h e f l o e was not e f f e c t i v e l y removed d u r i n g t h e c l a r i f i c a t i o n s t a g e , then the p o l l u t a n t s would show up i n t h e s e t t l e d e f f l u e n t . A s m a l l amount o f excess s o l i d s c o u l d cause a system t o exceed t h e P.C.B. o b j e c t i v e s (28). The c l a r i f i c a t i o n o p e r a t i o n used i n t h i s experiment i n v o l v e d two and one h a l f hours o f s e t t l i n g i n 20 cm d i a m e t e r r e a c t o r . T h i s was c o n s i d e r e d t o be an ample c l a r i f i c a t i o n s t e p . The t o t a l suspended s o l i d s , which were not removed under t h e s e c i r c u m s t a n c e s , p r o b a b l y would no t be removed i n a c o n v e n t i o n a l c l a r i f i e r . The n i t r o g e n l o a d i n g a f f e c t e d t h e t o t a l suspended s o l i d s l e v e l i n t h e s e t t l e d e f f l u e n t . As t h e BOD /N r a t i o was re d u c e d from 100/5.03 t o 5 100/3.19 w h i l e t h e BOD /P r a t i o was h e l d c o n s t a n t a t 100/1.11, t h e t o t a l suspended s o l i d s l e v e l i n t h e s e t t l e d e f f l u e n t dropped from 380 mg/L t o 47 mg/L. S i m i l a r l y , when t h e BOD^/N r a t i o was reduced from 100/3.98 t o 100/3.19 and BOD^/P r a t i o was h e l d c o n s t a n t a t 100/0.12, t h e s e t t l e d e f f l u e n t s t o t a l suspended s o l i d s l e v e l dropped from 245 mg/L t o 160 mg/L. Over t h e range o f v a l u e s s t u d i e d i n t h i s experiment, whenever the phosphorus l o a d i n g was h e l d c o n s t a n t and t h e n i t r o g e n l o a d i n g was d e c r e a s e d , t h e suspended s o l i d s l e v e l i n t h e s e t t l e d e f f l u e n t dropped. F i g u r e 6 i l l u s t r a t e s t h i s p o i n t . No r a t i o n a l e has been d e v e l o p e d f o r t h i s r e l a t i o n s h i p . 46 o BOD5/ P = 100/0.32 ^ 600 H M400 C O c> C O _ o o C J 80 L J £J 60 3 C O CD O 40 -I 20 H BODy P » 100/0.12 / BODyP * 100/Ul —I— 0 0 / 6 100/1 CO/2 —I— 0 0 / 3 — I — 100/4 100/5 B O Q / N RATIO FIGURE 6: EFFECT OF NITROGEN LOADING ON THE TOTAL SUSPENDED SOLIDS OF THE SETTLED EFFLUENT - "PURE LEACHATE" EXPERIt-ENT. In a 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 t r e a t m e n t p l a n t , a h i g h n i t r o g e n l o a d i n g can cause o p e r a t i o n a l problems. The v a r i o u s forms o f n i t r o g e n a r e c o n v e r t e d t o n i t r a t e by a u t o t r o p h i c b a c t e r i a i n t h e a e r a t i o n t a n k . When th e n i t r a t e s e n t e r t h e s e c o n d a r y c l a r i f i e r , which can become a n o x i c , t h e n i t r a t e s can be c o n v e r t e d t o n i t r o g e n gas. The gas can become t r a p p e d i n t h e s e t t l e d s l u d g e and can cause t h e s l u d g e t o r i s e . Thus, a h i g h n i t r o g e n l o a d i n g can cause h i g h suspended s o l i d s l e v e l s i n t h e e f f l u e n t from a c t i v a t e d s l u d g e p l a n t s . However, i n t h i s experiment, the h i g h suspended s o l i d s i n t h e e f f l u e n t , which o c c u r s w i t h a h i g h n i t r o g e n l o a d i n g , i s t h ought t o be a r e s u l t o f poor s e t t l i n g and not r i s i n g s l u d g e . T h i s c o n c l u s i o n i s based on p h y s i c a l o b s e r v a t i o n o f t h e s e t t l i n g s l u d g e and t h e f a c t t h a t t h e s e t t l e d s l u d g e was p a r t l y a n o x i c f o r l e s s t h a n 2 hours b e f o r e the sample was c o l l e c t e d . The B O D 5/P r a t i o had a s i g n i f i c a n t e f f e c t on t h e f i n a l e f f l u e n t ' s t o t a l suspended s o l i d s . In g e n e r a l , as t h e phosphorus l o a d i n g was d e c r e a s e d w i t h c o n s t a n t n i t r o g e n l o a d i n g t h e t o t a l suspended s o l i d s i n c r e a s e d . F i g u r e 7 and T a b l e X i l l u s t r a t e t h i s p o i n t . However, the e x a c t r e l a t i o n s h i p between the B O D 5/P r a t i o and t h e s e t t l e d e f f l u e n t ' s t o t a l suspended s o l i d s l e v e l i s not c l e a r from t h i s experiment. R e a c t o r D ( l ) had a BOD5/N/P r a t i o o f 100/3.98/0.32 and an e f f l u e n t suspended s o l i d s l e v e l o f 1805 mg/L. R e a c t o r E ( l ) had a BOD5/N/P r a t i o o f 100/3.98/0/12 but an e f f l u e n t t o t a l suspended s o l i d s l e v e l o f o n l y 245 mg/L. I t was thought t h a t any o f t h e r e a c t o r s , which had a B O D 5/P r a t i o o f l e s s t h a n 100/0.5, were not r e c e i v i n g enough phosphorus. Under the c o n d i t i o n s o f inadequate phosphorus l o a d i n g , t h e s e t t l e a b i l i t y o f t h e Biomass i n r e a c t o r D ( l ) was d e c r e a s e d . 48 $ 8 8 8 " 6/500- • 4 POO- -2JD00--^ i p o o -o 800-— 600-co Q 400-o C O 200+ Q I d O Z liJ 0. co z> CO o o 60+ 40+ 20+ + +- + B0D/N = 100/5.03 B0DVN= 100/3.98 X B0D/N= 100/3.19 + + 100/0.2 100/0.4 fOD/0.6 100/0.8 100/L0 I00/L2 B 0 D / P RATIO FIGURE 7: EFFECT OF PHOSPHORUS LOADING ON TOTAL SUSPENDED SOLIDS ON THE SETTLED EFFLUENT. 5-1-3 M e t a l s The l e a c h a t e c o n t a i n e d a wide range o f m e t a l s (see T a b l e I X ) . The l e a c h a t e f e e d f o r t h e "Pure L e a c h a t e " experiment was a n a l y z e d f o r t w e n t y - e i g h t d i f f e r e n t p a r a m e t e r s . Seven m e t a l s were s e l e c t e d because t h e i r c o n c e n t r a t i o n s i n t h e l e a c h a t e were f a r above t h e P.C.B.'s d i s c h a r g e o b j e c t i v e s . I f t h e s e seven m e t a l s r e c e i v e d adequate t r e a t m e n t , t h e n i t was assumed t h a t the o t h e r m e t a l s were j u s t as e f f e c t i v e l y t r e a t e d . The m e t a l s s t u d i e d were aluminum, cadmium, chromium, i r o n , l e a d , manganese, and z i n c . Mixed L i q u o r - A mass b a l a n c e f o r m e t a l s i n t h e m i x e d - l i q u o r was not as i n i t i a l l y e x p e c t e d . The m e t a l c o n c e n t r a t i o n s i n t h e mixed l i q u o r was expe c t e d t o be the same as i n t h e l e a c h a t e f e e d . F o r the seven m e t a l s s t u d i e d , t h e m i x e d - l i q u o r m e t a l c o n c e n t r a t i o n was 12% h i g h e r than i n t h e f e e d , a t the end o f the experiment. The r e a s o n f o r t h i s d i s c r e p a n c y was t h e mode o f d i g e s t e r o p e r a t i o n d u r i n g t h e a c c l i m a t i o n phase. D u r i n g t h i s time, l i t t l e s o l i d s (and t hus l i t t l e m e t a l s ) were removed from t h e d i g e s t e r . F o r 36 days, m e t a l s accumulated i n t h e d i g e s t e r . A t t h e s t a r t o f t h e s t e a d y - s t a t e phase, the m e t a l c o n c e n t r a t i o n was c a l c u l a t e d t o be over t w i c e the f e e d ' s m e t a l c o n c e n t r a t i o n . D u r i n g t h e s t e a d y - s t a t e phase, t h e m i x e d - l i q u o r m e t a l c o n c e n t r a t i o n s l o w l y dropped and approached t h e f e e d ' s m e t a l c o n c e n t r a t i o n . When t h e experiment was stopped, t h e m i x e d - l i q u o r m e t a l c o n c e n t r a t i o n s t i l l had not r e t u r n e d t o t h e o r i g i n a l l e v e l . N e u f e l d and Herman (13) computed t h e t o x i c l e v e l s f o r cadmium (5 mg Cd/ gVSS) and f o r z i n c (25 mg/ gVSS.) The m e t a l l e v e l s i n the r e a c t o r s a r e shown i n T a b l e X I I . TABLE X I I METAL CONCENTRATION IN MIXED LIQUOR SLUDGES-"PURE LEACHATE" EXPERIMENT METAL METAL CONCENTRATION IN SLUDGES (mg/qVSS) TOXIC LEVEL (13) (32) A ( l ) B ( l ) C ( l ) D ( l ) E ( l ) F ( l ) Cadium 5 0.012 0.011 0.010 0.009 0.010 0.011 Z i n c 25 8. 21 7.75 7.15 7.81 7.91 7/84 Aluminum 1.67 1.61 1.49 1.62 1.67 1.65 Chromium 25 0.082 0.079 0.275 0.079 0.079 0. 084 I r o n 141 135 126 134 138 138 Lead 1000 0.030 0.027 0.208 0.029 0.030 0.028 The m e t a l c o n c e n t r a t i o n s i n a l l t h e m i x e d - l i q u o r s were s u b s t a n t i a l l y below any t o x i c l e v e l s . S e t t l e d E f f l u e n t - The r e a c t o r w i t h a 20 day s l u d g e age was v e r y e f f e c t i v e i n removing m e t a l s . There was no d i r e c t c o r r e l a t i o n between the e f f i c i e n c y o f m e t a l removal and the n u t r i e n t l o a d i n g . However, t h e r e was good c o r r e l a t i o n between t h e t o t a l suspended s o l i d s l e v e l and the m e t a l c o n c e n t r a t i o n i n t h e s e t t l e d e f f l u e n t , as shown i n F i g u r e 8. 51 ~l 1 1 1 1 ' 1 1 — 1 1 1 1 — 20 40 60 SO 100 200 400 600 600 1000 2000 LOG OF SUSPENDED SOLIDS IN SETTLED EFFLUENT (rng/l) FIGURE 8: METAL CONCENTRATION VERSUS TOTAL SUSPENDED SOLIDS IN SETTLED EFFLUENT R e a c t o r D ( l ) had t h e l o w e s t t o t a l m e t a l removal e f f i c i e n c y (75%+). The r e a c t o r had a BOD5/N/P r a t i o o f 100/3.98/0.12. The e f f l u e n t from t h i s r e a c t o r f a i l e d t o meet s i x o f t h e seven P.C.B. o b j e c t i v e s f o r m e t a l s (See T a b l e X ) . R e a c t o r C ( l ) had t h e b e s t o v e r a l l performance. (See T a b l e X I I I ) TABLE X I I I EFFICIENCY OF METAL REMOVAL FROM REACTOR C ( l ) METAL A l Cd Zn Fe Pb Mn % M e t a l removal 97.1 99.3 99.4 99.6 98.2 98.7 Re a c t o r C ( l ) was t h e o n l y r e a c t o r t o meet f i v e o f t h e seven P.C.B. o b j e c t i v e s f o r m e t a l s . Only the i r o n and manganese c o n c e n t r a t i o n s were above the o b j e c t i v e s . (See T a b l e X) F i l t e r e d E f f l u e n t - There was no c o r r e l a t i o n between t h e s o l u b l e m e t a l c o n c e n t r a t i o n and t h e n u t r i e n t l o a d i n g . S o l u b l e i r o n and manganese c o n c e n t r a t i o n s d i d n o t meet t h e P.C.B. o b j e c t i v e s . T h i s i n d i c a t e s t h a t t h e b i o - t r e a t m e n t system may r e q u i r e a p o l i s h i n g s t e p , i n o r d e r t o meet e f f l u e n t g u i d e l i n e s . (See T a b l e X I ) . 5-1-4 N i t r o g e n and Phosphorus Mixed L i q u o r - The n i t r o g e n b a l a n c e , based on t o t a l K j e l d a h l n i t r o g e n , showed t h a t from 25 t o 60% o f n i t r o g e n added t o the r e a c t o r s was l o s t t o t h e atmosphere. I t appears t h a t the h i g h pH o f 8.5 and the l o n g a e r a t i o n time formed a s u i t a b l e environment f o r ammonia s t r i p p i n g . The phosphorus b a l a n c e , on t h e o t h e r hand, was more complete, w i t h 96% o f the i n p u t t o t a l phosphorus acc o u n t e d f o r . Helmers e t a l (19) have c o n c l u d e d t h a t a healthy s l u d g e has a t l e a s t a 7% n i t r o g e n c o n t e n t and a 1.2% phosphorus c o n t e n t . On t h i s b a s i s the r e a c t o r A ( l ) and B ( l ) had v i a b l e s l u d g e s . (See T a b l e XIV). Re a c t o r C ( l ) was low i n phosphorus and r e a c t o r s D ( 1 ) , E ( l ) , and F ( l ) s l u d g e were low i n both phosphorus and n i t r o g e n . TABLE XIV NITROGEN AND PHOSPHORUS CONTENT OF MIXED LIQUOR SLUDGES IN "PURE LEACHATE" EXPERIMENT NUTRIENT NUTRIENT CONTENT OF SLUDGE (% BY WEIGHT) RECOMMENDED MINIMUM (19) A ( l ) B ( l ) C ( l ) D ( l ) E ( l ) F ( l ) NITROGEN 7 7.2 7.5 6.0 6.2 2.9 5.9 PHOSPHORUS 1.2 2.4 2.9 3.3 0.6 0.3 0. 3 S e t t l e d E f f l u e n t - The n i t r o g e n c o n t e n t o f s e t t l e d e f f l u e n t i s d e f i n i t e l y e f f e c t e d by the n u t r i e n t l o a d i n g . I f the recommended BOD5/N r a t i o o f 100/5 was used, as i n r e a c t o r A ( l ) , c o n s i d e r a b l e n i t r o g e n appeared i n the s e t t l e d e f f l u e n t . When the B O D 5/N r a t i o was reduced t o 100/3.19, t h e s e t t l e d e f f l u e n t n i t r o g e n c o n c e n t r a t i o n dropped from 28mg/L t o 11 mg/L. When the B O D 5/P r a t i o was reduced from 100/1.11 to 100/0.12, t h e n i t r o g e n c o n c e n t r a t i o n i n c r e a s e d d r a m a t i c a l l y from 15.1 mg/L t o 149.3 mg/L. 54 The phosphorus c o n c e n t r a t i o n i n t h e s e t t l e d e f f l u e n t was not s i g n i f i c a n t l y a f f e c t e d by changes i n n u t r i e n t l o a d i n g . (See T a b l e X ) . F i l t e r e d E f f l u e n t - Based on the s o l u b l e n i t r o g e n d a t a , i t was d e t e r m i n e d t h a t between 40 and 90% o f t h e n i t r o g e n i n t h e s e t t l e d e f f l u e n t was s o l u b l e . T h i s meant t h a t t h e n i t r o g e n i n the e f f l u e n t was not bound up i n t h e b i o l o g i c a l f l o e . When a r e a c t o r was o p e r a t e d w i t h a BOD^/P r a t i o o f l e s s than o r e q u a l t o 100/0.32, t h e mixed l i q u o r s l u d g e was d e f i c i e n t i n phosphorus and h i g h l e v e l s o f n i t r o g e n showed up i n the s e t t l e d e f f l u e n t . H a t t i n g h (22) showed t h a t t h e r e i s a s i g n i f i c a n t i n t e r a c t i o n between the q u a n t i t i e s o f n i t r o g e n and phosphorus consumed i n a b i o l o g i c a l t r e a t m e n t system. In r e a c t o r s havincr a BOD /P r a t i o o f 100/0.32 o r l e s s , n i t r o g e n consumption by t h e mixed l i q u o r was i n h i b i t e d . Thus, the n i t r o g e n i n t h e l e a c h a t e f e e d p a s s e d t h r o u g h t h e r e a c t o r and come out as s o l u b l e n i t r o g e n i n t h e s e t t l e d e f f l u e n t . 5-1^-5 Micros-Organisms The l e a c h a t e was a h i g h l y c o n t a m i n a t e d wastewater. The c o n c e n t r a t i o n s o f some o f the p o l l u t a n t s found i n t h e l e a c h a t e were up t o 200 times t h e c o n c e n t r a t i o n s found i n domest i c sewage. (See Ta b l e V I ) . I t was d e c i d e d t o i n v e s t i g a t e t h e m i c r o b i a l p o p u l a t i o n found i n t h e r e a c t o r s , i n o r d e r t o d e v e l o p a comparison between a l e a c h a t e t r e a t m e n t system and a c o n v e n t i o n a l sewage t r e a t m e n t p l a n t . Samples o f the m i x e d - l i q u o r s were examined m i c r o s c o p i c a l l y by Dr. E.E. I s h i g u r o o f t h e Department o f M i c r o — b i o l o g y , U n i v e r s i t y o f B r i t i s h Columbia. Two main t y p e s o f b a c t e r i a were found. The f i r s t was p o s i t i v e l y i d e n t i f i e d as a c t i n o m y c e t e geodermatophilus.;- To the a u t h o r ' s k n o w l e d g e , t h i s b a c t e r i a has never been i s o l a t e d i n a sewage t r e a t m e n t system b e f o r e . The second was a z o o g l e a form, common t o domestic sewage p l a n t s . T h i s b a c t e r i a formed c l u s t e r s o f l o n g r o d s . A more s p e c i f i c i d e n t i f i c a t i o n was not p o s s i b l e . The z o o g l e a form was a l a r g e mass o f s i m i l a r - r t y p e b a c t e r i a , s t u c k t o g e t h e r i n a b i o l o g i c a l f l o e . (See F i g u r e The t y p e o f b a c t e r i a i n s i d e each system was a d e f i n i t e f u n c t i o n o f the m i x e d - l i q u o r phosphorus c o n c e n t r a t i o n . R e a c t o r s A ( l ) , B ( l ) and C ( l ) a l l had 90% geodermatophilus and 10% z o o g l e a f l o e . The c o n c e n t r a t i o n 9 o f a l l c e l l s was a p p r o x i m a t e l y 10 c e l l s / m l . I t i s u n u s u a l t o have one type o f b a c t e r i a predominate i n a wastewater t r e a t m e n t p l a n t . A l l t h e s e r e a c t o r s had a BOD^/P r a t i o o f 100/1.11. On t h e o t h e r hand, r e a c t o r D ( l ) had an e q u a l m i x t u r e o f t h e two b a c t e r i u m and had a BOD^/P r a t i o o f 100/0.32. R e a c t o r E ( l ) and F ( l ) had m o s t l y t h e z o o g l e a form i n the m i x e d - l i q u o r s , and t h e B O D 5/P r a t i o o f 100/0.119.. 5-1-6 Sludge The s l u d g e c h a r a c t e r i s t i c s were an i m p o r t a n t parameter i n e v a l u a t i n g t h e e f f e c t i v e n e s s o f b i o l o g i c a l t r e a t m e n t . 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 were a d e f i n i t e f u n c t i o n o f n u t r i e n t l o a d i n g . (See F i g u r e 10). 56 FIGURE 9 PHOTOMICROGRAPHS OF THE C2EODEBMATOPHILUS A N D Z O O G L E A F O R M S . R e a c t o r s A ( 1 ) , B (1) and C (1) a l l showed e x c e l l e n t s e t t l i n g c h a r a c t e r i s t i c s . The range o f n i t r o g e n l o a d i n g s had o n l y a s l i g h t e f f e c t , as l o n g as the BODyPhosphorus r a t i o was m a i n t a i n e d a t 100/1.11. When t h e BOD^/P r a t i o dropped t o 100/0.32 and lower, t h e sl 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 were poor. The s l u d g e volume i n d e x (SVI) c o u l d be used as an i n d i c a t i o n o f t h e s e t t l i n g c h a r a c t e r i s t i c s o f t h e s l u d g e . However, because t h e v a l u e o f t h e i n d e x , t h a t i s c h a r a c t e r i s t i c o f good s e t t l i n g s l u d g e , w i l l v a r y w i t h t h e m i x e d - l i q u o r c o n c e n t r a t i o n , o b s e r v e d v a l u e s a t a g i v e n p l a n t s h o u l d n ot be compared w i t h o t h e r v a l u e s r e p o r t e d i n t h e l i t e r a t u r e , u n l e s s t h e o p e r a t i n g c o n d i t i o n s a r e known t o be s i m i l a r . The m i x e d - l i q u o r suspended s o l i d s c o n c e n t r a t i o n (MLSS) i n a 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 l a n t i s a p p r o x i m a t e l y 2500 mg/L, whereas i n t h e l e a c h a t e t r e a t m e n t system s t u d i e d h e r e , t h e MLSS was 13,000 mg/L. Thus, c o n v e n t i o n a l v a l u e s o f SVI do hot a p p l y . In o r d e r t o e v a l u a t e t h e 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 i n t h i s s t u d y , i t i s proposed t o l o o k a t t h e s l u d g e volume per c e n t (S.V.P.C.). The S.V.P.C. was d e f i n e d by t h i s a u t h o r as "The volume o f s e t t l e d s l u d g e g e n e r a t e d p e r day, tim e s 100%, d i v i d e d by t h e t o t a l volume o f wastewater t r e a t e d p e r day." S.V.P.C. = Volume o f s l u d g e g e n e r a t e d p e r day x 100% (4) Volume o f e f f l u e n t t r e a t e d p e r day 59 T 1 1 1 1 1 1 1 I I r ' 0.2 0.4 0.6 0.8 IO 1.2 PHOSPHORUS LOADING ( B 0 D 5 / P ) 80 H o CL >: C O 6 0 H 40 H 20 H B 0 D 5 / P = I00/I.II I -1.0 3.0 2.0 4.0 NITROGEN LOADING ( B 0 D 5 / N ) 5.0 ~I— 6.0 FIGURE 11: E F F E C T OF NITROGEN AND PHOSPHORUS LOADING ON SLUDGE VOLUME PER CENT ( S . V . P . C . ) T h i s parameter then gave an i n d i c a t i o n o f t h e volume o f s l u d g e which a t r e a t m e n t system would g e n e r a t e . In t h i s s t u d y , the volume o f s l u d g e g e n e r a t e d was e q u a l t o the volume o f s l u d g e formed by the m i x e d - l i q u o r a f t e r two and one h a l f hours o f s e t t l i n g . The S.V.P.C. was n o t s i g n i f i c a n t l y a f f e c t e d o v e r the range o f BOD^/N r a t i o s i n v e s t i g a t e d . However, an i n c r e a s e i n phosphorus l o a d i n g r e s u l t e d i n a d e c r e a s e i n S.V.P.C. (See F i g u r e 11). A t h i g h phosphorus l o a d i n g s , the S.V.P.C. was a p p r o x i m a t e l y 35%. T h i s means t h a t 35% of t h e l e a c h a t e volume would have t o be f u r t h e r t r e a t e d . When t h e phosphorus l o a d i n g dropped, the S.V.P.C. i n c r e a s e d t o o v e r 7 5%. In t h i s s i t u a t i o n , 75% o f t h e l e a c h a t e would r e q u i r e f u r t h e r p r o c e s s i n g . As a m a t t e r o f i n t e r e s t , a c h a r a c t e r i z a t i o n was made o f the s e t t l e d s l u d g e from r e a c t o r C ( l ) and t h i s i s shown on T a b l e XV: TABLE XV CHARACTERISTICS OF SETTLED SLUDGE FROM REACTOR C ( l ) PARAMETER VALUE S.V.P.C. 35% BOD 7,000 mg/L COD 23,000 mg/L T o t a l S o l i d s 35,000 mg/L T o t a l Susp. S o l i d s 32,000 mg/L PH 8.7 Aluminum 30 mg/L Cadmium 0.21 mg/L Chromium 1.65 mg/L I r o n 2600 mg/L Lead 0.57 mg/L Manganese 90 mg/L TKN 1240 mg/L T o t a l Phosphorus 665 mg/L Z i n c 148 mg/L Thus, the amount and make-up o f t h i s s l u d g e would most c e r t a i n l y p r e s e n t a problem f o r f u r t h e r t r e a t m e n t . 5-1-7 K i n e t i c s The k i n e t i c p arameters were det e r m i n e d , i n o r d e r t o ( i ) f o l l o w any change i n r e a c t o r b e h a v i o r caused by the changing n u t r i e n t l o a d i n g and ( i i ) t o compare t h i s d a t a w i t h o t h e r works. The computations a r e l i s t e d i n Appendix A. There was some a m b i g u i t y o v e r the d e f i n i t i o n o f S^, the c o n c e n t r a t i o n o f s u b s t r a t e s u r r o u n d i n g t h e m i c r o - o r g a n i s m s . U l o t h (8) d e f i n e d as the mixed l i q u o r BOD,., wheras I r v i n e e t a l (32) d e f i n e d as t h e s o l u b l e BOD,.. In Appendix A, t h e k i n e t i c p arameters were c a l c u l a t e d u s i n g b o t h d e f i n i t i o n s . I t i s b e l i e v e d t h a t s o l u b l e BOD,, b e t t e r s u i t s the d e f i n i t i o n o f S •; however, because o f c e r t a i n l i m i t a t i o n s , e x p l a i n e d l a t e r , the k i n e t i c d a t a was c a l c u l a t e d u s i n g an S based on mixed l i q u o r BOD . 1 5 T h i s e n a b l e d t h e r e s u l t s o f t h i s s t u d y t o be compared w i t h t h e d a t a from t h e U l o t h (8) work. In o r d e r t o d e v e l o p p r o p e r k i n e t i c p a r a m e t e r s , the tr e a t m e n t system s h o u l d be o p e r a t e d o v e r a wide range o f s l u d g e ages. U n f o r t u n a t e l y , t h i s study used o n l y one s l u d g e age. The r e s u l t i s t h a t , i n s t e a d o f o b t a i n i n g a s e r i e s o f p o i n t s which form a l i n e , o n l y one p o i n t i s a v a i l a b l e and t h i s l i m i t e d the a c c u r a c y o f a b s o l u t e numbers. U l o t h (8) i n v e s t i g a t e d l e a c h a t e b i o s t a b i l i z a t i o n o v e r a range o f s l u d g e ages and was a b l e t o d e v e l o p s e v e r a l k i n e t i c p a r a m e t e r s . In t r y i n g t o e v a l u a t e the e f f e c t o f n u t r i e n t l o a d i n g on t h e s e parameters, t h e d a t a from t h i s study was t h e r e f o r e compared t o the f u n c t i o n a l r e l a t i o n s h i p s d e v e l o p e d by U l o t h ( 8 ) . In a d d i t i o n , an attempt was made t o e v a l u a t e t h e k i n e t i c parameters b a s e d on as s o l u b l e B O D 5 . The e f f e c t o f n u t r i e n t l o a d i n g can be seen i n F i g u r e s 14 (a) and 15 ( a ) . The f o u r r e a c t o r s , w i t h a B O D 5/P r a t i o e q u a l t o o r g r e a t e r than 100/0.32, a r e c l o s e l y grouped t o g e t h e r and c o r r e s p o n d e d t o the k i n e t i c parameters d e v e l o p e d by U l o t h ( 8 ) . The two r e a c t o r s w i t h B O D 5/P r a t i o o f 100/0.12 had k i n e t i c parameters which were d i f f e r e n t from U l o t h ' s (8) d a t a . The magnitude o f t h i s d i f f e r e n c e was n o t c a l c u l a b l e from the l i m i t e d numbers a v a i l a b l e . The v a l u e s o f the k i n e t i c p a r a m e t e r s , based on S i as s o l u b l e B0D5, can be d e r i v e d from F i g u r e s 14 (B) and 16 (B). S i n c e the f o u r r e a c t o r s w i t h B O D 5/P r a t i o s g r e a t e r o r e q u a l t o 100/0.32, compared c l o s e l y t o U l o t h 1 s (8) work, the d a t a from t h e s e f o u r r e a c t o r s was used t o c a l c u l a t e the k i n e t i c p a r a m e t e r s . E v a l u a t i o n o f t hese k i n e t i c v a l u e s d i d , however, r e q u i r e c o n s i d e r a b l e p e r s o n a l judgement, and c o r r e s p o n d e d t o a b i o l o g i c a l system which had an adequate n u t r i e n t l o a d i n g where (BOD/N/P r a t i o > 100/3.19/0.32) 5 — T a b l e XVI summarizes t h e r e s u l t s . TABLE XVI SUMMARY OF KINETIC PARAMETERS FROM "PURE LEACHATE" EXPERIMENT BASIS OF DATA KINETIC PARAMETER Y (mgVSS/mgBODs) K (Day-1) K (mgBOD5/mgVSS/Day K s (mgBOD5/L) U l o t h ( 8 ) - M i x e d L i q u o r BOD5 0. 332 0.0025 0.75 21375 "Pure L e a c h a t e " Expt. Mixed l i q u o r BOD5 0.525 0.0025 0.75 21375 i "Pure L e a c h a t e " E x p t . S o l u b l e BOD 5 0.438 0.0025 0.132 1.98 1 C o n v e n t i o n a l Sewage P l a n t Design (7) S o l u b l e BOD5 0.65 0.08 5.0 100 5-2 'Combination" L e a c h a t e and Sewage Experiment The purpose o f t h i s experiment was t o i n v e s t i g a t e t h e e f f e c t i v e n e s s o f combine t r e a t m e n t o f d o m e s t i c sewage and a h i g h - s t r e n g t h l a n d f i l l l e a c h a t e . The n u t r i e n t - d e f i c i e n t l e a c h a t e was combined w i t h the n u t r i e n t r i c h d o m e s t i c sewage and t r e a t e d i n t h e same ty p e o f system as i n t h e "Pure L e a c h a t e " experiment. Based on t h e work o f B o y l e and Ham (26), i t was e s t i m a t e d t h a t the system would f a i l when 5% (volume leachate/volume o f feed) l e a c h a t e was t r e a t e d . However, i n t h i s s t u d y , up t o 20% (v/v) l e a c h a t e was s u c c e s s f u l l y t r e a t e d . The r e s u l t s o f the experiment a r e t a b u l a t e d i n T a b l e X V I I -C h a r a c t e r i s t i c s o f Feed; T a b l e X V I I I - M i x e d - L i q u o r C h a r a c t e r i s t i c s ; T a b l e X l X ^ S e t t l e d E f f l u e n t C h a r a c t e r i s t i c s ; and T a b l e X X - F i l t e r e d E f f l u e n t C h a r a c t e r i s t i c s . 5-2-1 B0D 5 Mixed L i q u o r From T a b l e XVIII i t can be seen t h a t t h e m i x e d - l i q u o r BOD,, i n c r e a s e d w i t h i n c r e a s e d l e a c h a t e l o a d i n g . However, the p e r c e n t BOD,, r e d u c t i o n a l s o i n c r e a s e d w i t h i n c r e a s e d l o a d i n g , as shown i n T a b l e XXI. TABLE XVII CHARACTERISTICS OF FEED FOR "COMBINATION" EXPERIMENT C h a r a c t e r i s t i c , ( a l l , except pH, i n mg/L) Lea c h a t e Sewage R e a c t o r A(2) 0%Leachate Rea c t o r B(2) l % L e a c h a t e R e a c t o r C(2) 3%Leachate R e a c t o r D(2) 6%Leachate Rea c t o r E(2) 10%Leachate R e a c t o r F(2) 20%Leachate RODc 18025 56 56 236 595 1134 1850 3650 D U 1 J b COD 28830 124 124 411 985 1846 3000 5870 T o t a l S o l i d s 13940 176 176 314 589 1002 1550 2930 T o t a l V o l a t i l e 7560 84 84 159 308 533 832 1580 S o l i d s 171 2 96 T o t a l Suspended 1290 47 47 59 84 122 S o l i d s 124 202 V o l a t i l e Suspended 826 46 46 54 69 93 S o l i d s A l k a l i n i t y 5265 100 100 152 255 410 617 1133 P H 5.0 6.9 6.9 6.9 6.9 6.9 6.9 6.9 Aluminum 3.06 0. 33 0.33 0.357 0.412 0.494 0.633 0.876 Cadmium 0.344 0.0031 0.0031 0.0065 0.0133 0.0236 0.0372 0.0713 Chromium 0.44 0.007 0.007 0.0113 0.020 0.0318 0.0503 0.0936 I r o n 750 0.694 0.694 5.15 23.2 45.7 75.6 151 Lead 0.106 0.0101 0.0101 0.0111 0.0130 0.0159 0.0197 0.0293 Manganese 20. 5 0.099 0.099 0.303 0.711 1.32 2.14 4.18 TKN 560 13.7 13.7 19.16 30.01 46.48 66.96 123.0 TP 11.4 2.4 2.4 2 .49 2.67 2.94 3.30 4.20 Z i n c 71.0 0.0457 0.0457 0.0755 2 .18 4. 30 | 7.14 14.2 100 100 100 100 100__ 100 100 j BOD5/N/P 1 3.107 24.46 8.119 5! 044 4.099 3.619 3.616 0.0632 4.29 T."055 0.449 0.259 0.291 0.115 TABLE XVIII MIXED LIQUOR CHARACTERISTICS FOR "COMBINATION" EXPERIMENT C h a r a c t e r i s t i c ( a l l , R e a c t o r R e a c t o r Reactor Reactor R e a c t o r Reactor except ph, mg/L) A(2) B(2) C(2) D(2) E(2) F(2) BOD 5 38 69 102 179 227 346 COD 62 172 391 628 993 1577 T o t a l S o l i d s 320 492 752 1120 1680 2768 T o t a l V o l a t i l e 128 200 332 540 860 1428 s o l i d s T o t a l Suspended 54 184 394 680 1205 2200 S o l i d s V o l a t i l e Suspended 44 138 335 ' 490 789 1386 S o l i d s A l k a l i n i t y 15 60 155 310 340 490 pH 6.0 7.8 8.4 8.6 8.6 8.7 Aluminum 0.281 0.388 0.450 0.500 0.675 0.963 Cadmium 0.00186 0.0060 0.0181 0.0221 0.0353 0.0651 Chromium 0.0267 0.0160 0.0393 0.310 0.010 0.0952 Ir o n 3.21 11.5 25.37 48.3 81.5 141.2 Lead 0.0274 0.0350 0.0380 0.0410 0.0426 0.0547 Manganese 0.17 3 0.410 0.789 1.45 2.51 3.93 TKN 5.3 12.0 28.8 45.4 65.5 93.0 TP 3.6 3.8 3.9 4.2 4.8 5.1 Z i n c 0.341 0.881 2.10 4.04 6.05 9.78 TABLE XIX SETTLED EFFLUENT CHARACTERISTICS FOR "COMBINATION" EXPERIMENT C h a r a c t e r i s t i c ( a l l , . R e a c t o r R e a c t o r Reactor R e a c t o r R e a c t o r Reactor P.C.B. except pH, mg/L) A (2) B(2) C(2) D(2) E(2) F(2) O b j e c t i v e (28) BOD 5 11 5 14 11 8 135 16 45 COD 15 29 66 40 73 T o t a l S o l i d s 260 324 388 476 596 792 T o t a l V o l a t i l e 60 108 92 100 156 176 S o l i d s 20 T o t a l Suspended 16 7 10 22 18 S o l i d s 20 V o l a t i l e Suspended 16 7 10 22 18 S o l i d s A l k a l i n i t y 15 52.5 140 194 218 313 P H 6.0 7.8 8.4 8.6 8.6 8.7 Aluminum 0.129 0.058 0.050 0.054 0.033 0.042 0.5 Cadmium 0.00078 0.00031 0.00093 0.00093 0.00047j 0.00062 0.005 Chromium 0.0143 0.0048 0.00476 0.0270 0.0095 0.0127 0.10 Ir o n - 0.647 0.530 0.990 1.72 0.815 1.28 0.3 Lead 0.007 3 0.0032 0.0027 0.0027 0.0041 0.0018 0.05 Manganese 0.0437 0.0150 0.117 0.119 0.0541 0.0308 0.05 TKN 2.8 2.8 3.1 4.2 2.5 ! 13.4 15.0 TP . 2.4 0. 38 0.18 0.19 0.12 ! 0.17 4.5 Z i n c i 0.216 0.0908 ; — 0.109 i 0.162 0.0865 0.0822 0.5 TABLE XX FILTERED EFFLUENT CHARACTERISTICS FOR "COMBINATION" EXPERIMENT C h a r a c t e r i s t i c ( a l l x except pH, mg/L) R e a c t o r A(2) R e a c t o r B(2) Reactor C(2) Reactor D(2) Reactor E(2) Reactor F(2) P.C.B. (28) O b j e c t i v e BODc 2.6 3.2 6.2 5.6 8.3 8.6 45 COD 12 26 18 . 29 40 95 T o t a l S o l i d s 236 344 372 508 588 808 T o t a l V o l a t i l e 72 128 64 124 140 208 S o l i d s T o t a 1'.. Su spend ed - — — "*" S o l i d s V o l a t i l e Suspended - — -j S o l i d s A l k a n i n i t y 17.5 50 118 198 230 320 pH 6.0 7.8 8.4 8.6 8.6 8.7 Aluminum 0.050 0.031 0.031 0.063 0.038 0.034 0.5 ' Cadmium 0.00064 0.0002 3 0.00035 0.00053 0.00035 0.00053 0.005 Chromium 0.0072 0.0036 0.0036 0.0060 0.0084 0.0107 0.10 Iron 0.112 0.0956 0.0797 0.152 0.0635 0.0874 0.3 Lead 0.0014 0.0011 N.D N.D N.D N.D 0.05 Manganese 0.0252 0.0029 0.0852 0.0970 0.0606 0.0406 0.05 'TKN. 1.7 1.7 2.0 j 2.0 2.2 2.8 15.0 j TP . 0.13 0.06 0.06 0.06 0.12 4.5 Z i n c 0.199 0.0819 0.0456 j 0.0629 0.0637 0.0613 0.5 ' TABLE XXI BOD REDUCTION IN MIXED LIQUORS VERSUS APPLIED LOADINGS Re a c t o r A(2) B(2) C(2) D(2) E(2) F(2) BOD Feed (mg/L) 56 236 595 1134 1850 3650| | % R e d u c t i o n BOD,, i n mixed l i q u o r 32 70 83 84 88 ! H S e t t l e d E f f l u e n t - The s e t t l e d BOD 5 d a t a (Table XIX) shows a p a t t e r n which has become t y p i c a l f o r most s e t t l e d e f f l u e n t parameters. Even over a wide range o f l e a c h a t e f e e d c o n c e n t r a t i o n s , the s e t t l e d e f f l u e n t BOD,, does not show any t r e n d s and a l l v a l u e s a r e w e l l below the B.C. P o l l u t i o n C o n t r o l Board o b j e c t i v e s (28). In a l l systems, the BOD,, d e c r e a s e d t o a base l e v e l o f a p p r o x i m a t e l y 10 mg/L. T h i s means t h a t the s e t t l e d BOD,, r e d u c t i o n ranged from 80 t o 99.6%. 5 F i l t e r e d E f f l u e n t - As shown i n T a b l e XX t h e s o l u b l e BOD^ showed o n l y a s l i g h t i n c r e a s e , w i t h an i n c r e a s e i n l e a c h a t e l o a d i n g . A p p r o x i m a t e l y h a l f the s e t t l e d e f f l u e n t B0D c was s o l u b l e BOD . T h i s i n d i c a t e s a good 5 5 s o l i d - l i q u i d s e p a r a t i o n , i n e v e r y system s t u d i e d . 5-2-2 Suspended S o l i d s Mixed L i q u o r - THE MLVSS l e v e l was m o n i t o r e d weekly. T h i s d a t a was used t o e s t i m a t e when s t e a d y - s t a t e c o n d i t i o n s had been a c h i e v e d . F i g u r e 12 shows the development o f MLVSS i n t h i s experiment. Thus, i t can be seen t h a t s t e a d y - s t a t e c o n d i t i o n s were a c h i e v e d a p p r o x i m a t e l y 37 days a f t e r s t a r t - u p . S e t t l e d E f f l u e n t - As w i t h BOD^, the s e t t l e d e f f l u e n t t o t a l suspended s o l i d s c o n c e n t r a t i o n d i d not show any t r e n d s w i t h l e a c h a t e l o a d i n g . (See T a b l e XIX). A l l d i g e s t e r s had v e r y low suspended s o l i d s l e v e l s i n the s e t t l e d e f f l u e n t . The suspended s o l i d s a l s o p r o v e d t o be 100% v o l a t i l e . I I I I I I I I I 10 20 30 40 — — TIME (DAYS) > FIGURE 12: MIXED LIQUOR VOLATILE SUSPENDED SOLIDS VERSUS TIME FRO"' START-UP FOR "COMBINATION" EXPERIMENT 5-2-3 • M e t a l s Mixed L i q u o r - The mass b a l a n c e f o r m e t a l s i n the mixed-l i q u o r was, a g a i n , not as i n i t i a l l y e x p e c t e d . R e s u l t s a r e shown i n T a b l e X V I I I . At s t e a d y - s t a t e c o n d i t i o n s , the m e t a l c o n c e n t r a t i o n i n t h e m i x e d - l i q u o r s h o u l d have been e q u a l t o t h e m e t a l c o n c e n t r a t i o n i n t h e f e e d . A l l r e a c t o r s , however, d i d not e x h i b i t t h e same degree of d i f f e r e n c e . R e a c t o r A(2) was the worst i n t h i s r e s p e c t , w i t h mixed-l i q u o r m e t a l c o n c e n t r a t i o n s a p p r o x i m a t e l y 3 x h i g h e r than t h a t i n the f e e d . T h i s d i f f e r e n c e d e c r e a s e d as the amount of l e a c h a t e i n the f e e d was i n c r e a s e d . The r e a s o n f o r t h i s p a t t e r n was a t t r i b u t e d t o t h e mode o f d i g e s t e r o p e r a t i o n d u r i n g t h e a c c l i m a t i o n phase and c o n t a m i n a t i o n from the i n i t i a l seed. S i n c e t h e m i x e d - l i q u o r suspended s o l i d s were kept i n th e d i g e s t e r d u r i n g t h e a c c l i m a t i o n phase, the m e t a l s , which were bound t o the f l o e , i n c r e a s e d i n c o n c e n t r a t i o n . A l s o , t h e r e were m e t a l s added t o the d i g e s t e r s from the i n i t i a l seed from d i g e s t e r A d ) . T h i s seed c o n s i s t e d o f 40 mis o f m i x e d - l i q u o r from d i g e s t e r A ( l ) . A f t e r the m e t a l a n a l y s i s was d o n e , i t was c a l c u l a t e d , f o r example, t h a t , a t the s t a r t o f t h e experiment, d i g e s t e r A(2) had a c o n c e n t r a t i o n o f z i n c i n t h e m i x e d - l i q u o r which was 14 x the z i n c c o n c e n t r a t i o n i n the f e e d ; whereas, d i g e s t F(2) had a z i n c m i x e d - l i q u o r c o n c e n t r a t i o n which was almost e q u a l t o the f e e d c o n c e n t r a t i o n . D u r i n g the s t e a d y - s t a t e phase, the m i x e d - l i q u o r metal c o n c e n t r a t i o n s l o w l y dropped and approached t h e f e e d ' s m e t a l c o n c e n t r a t i o n . The r e a c t o r s , w i t h a s m a l l % o f l e a c h a t e i n t h e i r f e e d , were the most a f f e c t e d by t h e b u i l d - u p o f m e t a l s d u r i n g the a c c l i m a t i o n phase and by t h e i n i t i a l seed c o n t a m i n a t i o n . Even when the experiment t e r m i n a t e d , t h e m e t a l l e v e l s i n the r e a c t o r s s t i l l had not r e t u r n e d t o the meta l c o n c e n t r a t i o n s found i n the f e e d sample. N e u f e l d and Herman (13) had computed the t o x i c l e v e l s f o r cadmium (5 mg Cd/gVSS) and f o r z i n c (25 mg/gVSS). The maximum l e v e l s f o r t h e s e m e t a l s was i n r e a c t o r A ( 2 ) : 0.042 mg Cd/gVSS and 7.75 mg zinc/gVSS. (See T a b l e XXII.) T h i s p r o b a b l y i n d i c a t e s t h a t t hose m e t a l c o n c e n t r a t i o n i n the m i x e d - l i q u o r were not a t a t o x i c l e v e l . TABLE XXII METAL CONCENTRATION IN MIXED LIQUOR SLUDGES - "COMBINATION" EXPERIMENT METAL METAL CO NCENTRATION IN SLUDGES (mg/gVSS) T o x i c L e v e l (13( (32) A(2) B(2) C(2) D(2) E(2) F(2) Cadium 5 0.03 0.04 0,05 0.04 0.04 0.06 Z i n c 25 3.23 5.79 6.13 8.12 7.59 7.01 Aluminum 5.25 2.59 1.25 0.89 0.81 0.67 Chromium 25 0.44 0.09 0.11 0.62 0.01 0.06 I r o n 70.5 82.6 75.5 98.3 103. 102. Lead 1000 0.59 0.25 0.11 0.08 0 r05 0.04 S e t t l e d E f f l u e n t - T h i s b i o - t r e a t m e n t system, w i t h a 20 day s l u d g e age, was v e r y e f f e c t i v e i n removing metals (see T a b l e XIX). No c o r r e l a t i o n was found between metal removal and n u t r i e n t l o a d i n g s . The system seemed t o remove the metals down t o a base l e v e l , r e g a r d -l e s s o f the f e e d c o n c e n t r a t i o n . I t i s , t h u s , d i f f i c u l t t o draw s p e c i f i c c o n c l u s i o n s , because o f the non-steady s t a t e c o n s i d i t i o n s o f the m e t a l b a l a n c e . However, the e f f l u e n t from a l l the r e a c t o r s c o n s i s t e n t l y met the P.C.B.'s o b j e c t i v e s f o r aluminum, cadmium, chromium, l e a d , and z i n c . The r e a c t o r s f a i l e d t o remove enough i r o n and manganese t o meet the d i s c h a r g e o b j e c t i v e s . F i l t e r e d E f f l u e n t - There was no c o r r e l a t i o n between the s o l u b l e metal c o n c e n t r a t i o n and the n u t r i e n t l o a d i n g due t o non-steady s t a t e c o n d i t i o n s o f the m e t a l b a l a n c e . The P.C.B.'s o b j e c t i v e s f o r e f f l u e n t d i s c h a r g e was met f o r aluminum, cadmium, chromium, l e a d , i r o n and z i n c , but n o t f o r manganese. The a d d i t i o n o f 3% (volume Leachate/volume o f feed) o r g r e a t e r o f l e a c h a t e can r e s u l t i n c o n c e n t r a t i o n s o f s o l u b l e manganese above the approved l e v e l s . An a d d i t i o n a l p o l i s h i n g s t e p may be r e q u i r e d i n o r d e r t o meet e f f l u e n t g u i d e l i n e s . (See T a b l e XX) 5-2-4 N i t r o g e n and Phosphorus Mixed L i q u o r - As i n the "Pure L e a c h a t e " e x p e r i m e n t a p p r o x i -mately 25% o f the n i t r o g e n as TKN, was l o s t t o the atmosphere. T h i s was t r u e even though the PH ranged from 6.0, i n r e a c t o r A ( 2 ) , t o 8.7, i n r e a c t o r F ( 2 ) . The phosphorus m a t e r i a l b a l a n c e was n o t as c l o s e as i n the "Pure L e a c h a t e " Experiment. The m i x e d - l i q u o r phosphorus con-c e n t r a t i o n was a p p r o x i m a t e l y 10% h i g h e r than the f e e d ' s phosphorus 74 c o n c e n t r a t i o n . (See Table XVII and Table XVIIT).' No reason could be found f o r t h i s imbalance. Helmers e t a l (19) concluded t h a t a he a l t h y sludge would have a n i t r o g e n content of at l e a s t 7% and a phosphorus content o f at l e a s t 1.2%. The n i t r o g e n and phosphorus content o f the r e a c t o r s ' sludge i s shown i n Table X X I I I . TABLE X X I I I NITROGEN AND PHOSPHORUS CONTENT OF SLUDGES IN "COMBINATION" EXPERIMENT REACTOR NO. BOD5/N/P OF FEED NITROGEN CONTENT OF SLUDGE(mgTKN)(100%) (mgVSS) PHOSPHORUS CONTENT OF SLUDGE ~(mgTF) (100%) (mgVSS) A(2) 100/24.5/4.29 8.2 8.0 B(2) 100/8.12/1,06 7.5 2.7 C(2) 100/5.04/0.45 8,0 1.1 b(2) 100/4,10/0.26 8,8 0,84 E(2) 100/3.62/0.29 7.9 0.60 F(2) 100/3,62/0,12 6.5 0.36 Based on the Helmers e t a l (19) c r i t e r i o n , the minimum BOD5/N r a t i o , which produced a sludge w i t h the proper n i t r o g e n content, was 100/3,62. S i m i l a r l y , the minimum B O D 5/P r a t i o , which would g i v e a sludge the proper phosphorus content, was approximately 100/0,45, S e t t l e d E f f l u e n t - The n i t r o g e n c o n c e n t r a t i o n s i n the s e t t l e d e f f l u e n t s was g e n e r a l l y t o be v e r y low. (See Ta b l e XIX.) Even when BOD 5/N r a t i o was 100/24.5 i n r e a c t o r A ( 2 ) , t h e r e was o n l y 2.8 mg/L o f t o t a l K j e l d a h l n i t r o g e n i n the e f f l u e n t . However, when the BOD5/P r a t i o dropped below 100/0.29, the n i t r o g e n c o n c e n t r a t i o n r o s e t o 13.4 mg/L. Even though t h i s r e p r e s e n t s a removal r a t e o f 89%, i t was thought t h a t t h e low phosphorus l o a d i n g i n h i b i t e d the a b i l i t y o f the m i x e d - l i q u o r t o a s s i m i l a t e n i t r o g e n . In a l l o f the r e a c t o r s which has some p o r t i o n o f l e a c h a t e i n t h e i r f e e d , the t o t a l phosphorus l e v e l s i n the s e t t l e d e f f l u e n t were below 0.40 mg/L. T h i s r e p r e s e n t s removal r a t e s r a n g i n g from 85% i n B(2) t o 95% i n F ( 2 ) . R e a c t o r ' s A(2) f e e d c o n s i s t e d c o m p l e t e l y o f domestic sewage. The phosphorus went r i g h t through the system, which r e s u l t e d i n a 0% removal r a t e . T h i s r e a c t o r had the l o w e s t concen-t r a t i o n o f phosphorus i n i t s f e e d and the h i g h e s t c o n c e n t r a t i o n o f phosphorus i n i t s e f f l u e n t . F i l t e r e d E f f l u e n t - In a l l the r e a c t o r s , the s o l u b l e n i t r o g e n was reduced t o a s i m i l a r base l e v e l between 1.5 and 3.0 mg/L. I t was deter m i n e d t h a t from 20 t o 90% o f the n i t r o g e n i n the s e t t l e d e f f l u e n t was s o l u b l e . There was no r e l a t i o n s h i p between the n u t r i e n t l o a d i n g and the s o l u b l e n i t r o g e n l e v e l i n the e f f l u e n t . In a s i m i l a r manner, the s o l u b l e phosphorus l e v e l i n the e f f l u e n t from a l l the r e a c t o r s was reduced t o a base l e v e l between 0.05 to 0.15 mg/L. U n f o r t u n a t e l y , the s o l u b l e phosphorus sample from r e a c t o r A(2) was l o s t d u r i n g a n a l y s i s . I t was dete r m i n e d t h a t from 30 t o 70% o f phosphorus i n the s e t t l e d e f f l u e n t was s o l u b l e . The p e r c e n t a g e o f soluble phosphorus i n the s e t t l e d e f f l u e n t increased with a decrease i n phosphorus loading. 5-2-5- Micro-Organisms Although the systems were a mixture of leachate and domestic sewage, the predominate micro-organism i n a l l the reactors was the zooglea form, which i s common to domestic sewage pl a n t s . The geo d e r m a t h o p h i l u s was present, but only i n l i m i t e d numbers. Posi t i v e i d e n t i f i c a t i o n of micro-organism was very d i f f i c u l t , . because of the large amount of i n e r t debris i n the b i o - f l o c . This debris consisted of dead c e l l s , inorganics and insoluble matter. 5-2-6 Sludge The sludge s e t t l e d well i n a l l of the reactors as shown i n Figure 13. I t was expected that, because of the lower nutrient loading i n reactor E(2) (BOD5/N/P = 100/3.62/0.29) and reactor F (2) (BOD5/N/P = 100/3.62/0.12), the sludge i n these systems would bulk and s e t t l e poorly. This was not the case. The volume of sludge produced, per weight of BOD5 destroyed, remained r e l a t i v e l y constant i n a l l of the reactors. However, the weight of sludge produced, per weight of BOD5 destroyed, a c t u a l l y decreased with increased leachate addition. Table XXIV i l l u s t r a t e s these r e s u l t s . TABLE XXIV SLUDGE PRODUCTION FOR "COMBINATION" EXPERIMENT DIGESTER NUMBER A(2) B(2) C(2) D(2) E(2) F(2) % LEACHATE 0 1 3 6 10 20 ml Sludge A BODsmg/L 0.011 0.030 0.019 0.025 0.02 3 0.018 mg Sludge A BOD5 mg/L 0.084 0.77 0.66 0.59 0.64 0.60 5-2-7 K i n e t i c s The k i n e t i c p arameters were d e t e r m i n e d , u s i n g m i x e d - l i q u o r BOD5 and f i l t e r e d B O D 5 d a t a . (See Appendix A.) The k i n e t i c p a r a m e t e r s e v a l u a t e d f o r combined t r e a t m e n t were compared t o the v a l u e s d e v e l o p e d from "Pure L e a c h a t e " t r e a t m e n t . I t was assumed t h a t t h e n u t r i e n t l o a d i n g would not be a l i m i t i n g f a c t o r i n t h e "Combination" experiment. The v a l u e s o f K and Ks were dete r m i n e d as p e r F i g u r e 16 and shown i n T a b l e XXV. The d a t a a l l o w e d a r e a s o n a b l e e s t i m a t e o f K and K s. The v a l u e s o f Y and K3 were dete r m i n e d as p e r F i g u r e 15. The l i m i t a t i o n o f h a v i n g o n l y one s l u d g e age becomes v e r y a p p a r e n t . The l i n e d e v e l o p e d i n t h e "Pure L e a c h a t e " experiment was p l o t t e d on F i g u r e 17. T h i s l i n e c o r r e s p o n d s r e a s o n a b l y w e l l w i t h d a t a from r e a c t o r s which had more than 3% l e a c h a t e a d d i t i o n . The d a t a p r e s e n t e d s h o u l d not be c o n s t r u e d as a b s o l u t e i n a c c u r a c y , but s i m p l y i n d i c a t i v e o f " t r e n d " i n the k i n e t i c e v a l u a t i o n o f t h e s e r e a c t o r s . TABLE XXV SUMMARY OF KINETIC PARAMETERS FROM "COMBINATION" EXPERIMENT KINETIC PARAMETER BASIS OF DATA Y (mgVSS/mgBOD) Kd (DAY-1) K (mgBOD/mgVS S/DAY) (mgBOD/L) Mixed L i q u o r BOD 5 0.525 0.0025 0.174 139 F i l t e r e d BOD 5 0.438 0 0025 .... 0.172 3.61 5-3 Comparison o f "Pure L e a c h a t e " and "Combination" Experiment The n u t r i e n t l o a d i n g s i n the "Pure L e a c h a t e " experiment ranged from 100/5/1.11 t o 100/3.2/0.12 and i n the "Combination" experiment from 100/24.5/4.29 t o 100/3.62/0.12. The F/M r a t i o r a t i o s ranged from 0.117 t o 0.148 i n the "Pure L e a c h a t e " experiment and from 0.064 t o 0.131 i n the "Combination" experiment. Both experiments had t h e same slud g e age o f 20 days and thus were e x p e c t e d t o show s i m i l a r r e s u l t s . However, i n the "Pure L e a c h a t e " experiment, the slu d g e b u l k e d b a d l y when the n u t r i e n t l o a d i n g was below 100/3.19/0.5; whereas, i n the "Combination" experiment, even though the n u t r i e n t l o a d i n g was d e c r e a s e d t o 100/3.62 /0.12, the system s t i l l performed w e l l . The c r i t i c a l d i f f e r e n c e between the two experiments seemed t o be the v o l u m e t r i c BOD l o a d i n g . The "Pure L e a c h a t e " experiment had a v o l u m e t r i c BOD l o a d i n g of 1.0 kg B0D5/Day/Cubic Meter o f a e r a t i o n tank w h i l e i n the "Combination" experiment, the h i g h e s t v a l u e was o n l y 0.18 kg B O D 5 / Day/Cubic Meter. T h i s i n d i c a t e s t h a t t h e minimum n u t r i e n t l o a d i n g , which would ensure good performance, seems t o be a f u n c t i o n o f v o l u m e t r i c BOD5 l o a d i n g . I f the v o l u m e t r i c l o a d i n g i s low, then the r e q u i r e d n u t r i e n t s w i l l be low a l s o . As the v o l u m e t r i c l o a d i n g i n c r e a s e s , so does the r e q u i r e d l e v e l o f n u t r i e n t s . T h i s i s what one might e x p e c t , i n d e a l i n g w i t h a m i c r o b i o l o g i c a l system. The main mi c r o - o r g a n i s m s f u n c t i o n i n g i n the l e a c h a t e t r e a t m e n t systems a r e th o s e commonly found i n domestic sewage p l a n t s , as w e l l as the microbe g e c d e r i t i a t h o p h i l o s . However, the g e o d e n t ^ t h o p h i l o s r e q u i r e d a h i g h c o n c e n t r a t i o n o f phosphorus. In d i g e s t e r s C ( l ) and B ( 2 ) , where BOD^/P r a t i o s were s i m i l a r , b u t the a b s o l u t e c o n c e n t r a t i o n s o f phosphorus were v e r y d i f f e r e n t , the g e o d e r m a t h o p h i l o s o n l y t h r i v e d i n the system w i t h the h i g h phosphorus c o n c e n t r a t i o n o f 271 mg/L. The k i n e t i c p a r a m e t e r s were a l s o " e s t i m a t e d " f o r b o t h e x p e r i m e n t s . The f o l l o w i n g parameter v a l u e s c o u l d p o s s i b l e be a p p l i e d t o b o t h e x p e r i m e n t s . Parameter V a l u e ( B a s e d on S o l u b l e BOD5) Y(mgVSSP) 0.438 (mgBODs) K d ( D a y _ 1 ) 0.0025 K (mg/mgVSS/Day) 0.150 K (mg/Liter) 2.50 CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS 6 - 1 C o n c l u s i o n s 1) When t r e a t i n g h i g h s t r e n g t h l e a c h a t e i n an extended a e r a t i o n system, w i t h a s l u d g e age o f 20 days, the r e q u i r e d n u t r i e n t s can be s i g n i f i c a n t l y r e d u c e d below the recommended v a l u e o f 100/5/1. N u t r i e n t l o a d i n g v a l u e s as low as 100/3.19/0.5 produced good q u a l i t y e f f l u e n t . 2) At low v o l u m e t r i c BOD l o a d i n g s o f about 0.16 kg BOD^/Day/ Cu b i c Meter, a low n u t r i e n t l o a d i n g o f 100/3.62/0.12 does not e f f e c t t h e t r e a t m e n t e f f i c i e n c y . However, a t a r e l a t i v e l y h i g h v o l u m e t r i c l o a d i n g o f 1.0 kg BOD^/Day/Cubic Meter, t h e mimimum n u t r i e n t l o a d i n g needed was 100/3.19/0.5. Thus the i n c r e a s e i n v o l u m e t r i c l o a d i n g r e q u i r e d a c o r r e s p o n d i n g i n c r e a s e i n phosphorus i n p u t . 3) When t h e n u t r i e n t l o a d i n g was s u f f i c i e n t l y r e d uced, the slu d g e b u l k e d and s e t t l e d p o o r l y . T h i s r e s u l t e d i n a h i g h l e v e l o f suspended s o l i d s i n t h e f i n a l e f f l u e n t . S i n c e the m e t a l s were bound t o t h e suspended s o l i d s , t h e meta l c o n c e n t r a t i o n s i n the f i n a l e f f l u e n t a l s o i n c r e a s e d . 4) When the phosphorus l o a d i n g i s l e s s t h a n 100/0.5, the a b i l i t y o f t h e m i x e d - l i q u o r s l u d g e t o absorb n i t r o g e n was reduced. 5) In t h e "Pure L e a c h a t e " experiment, t h e r e was a d e f i n i t e r e l a t i o n s h i p between t h e typ e o f m i c r o b i a l p o p u l a t i o n found i n each r e a c t o r and the n u t r i e n t l o a d i n g . No such r e l a t i o n s h i p was found i n t h e "Combined" experiment. 6) The e f f e c t s o f h i g h c o n c e n t r a t i o n s ;of m e t a l s i n the l e a c h a t e f e e d was mimimized by th e e x t r e m e l y h i g h l e v e l s o f B O D 5 . The h i g h B O D 5 l o a d i n g r e s u l t e d i n a h i g h l e v e l o f m i x e d - l i q u o r v o l a t i l e suspended s o l i d s . The r a t i o o f m e t a l s t o v o l a t i l e suspended s o l i d s found i n both experiments was below l e v e l s thought t o be t o x i c . 7) The s o l i d s s e p a r a t i o n c h a r a c t e r i s t i c s o f the s l u d g e and i t s t r e a t m e n t w i l l be v e r y i m p o r t a n t . A w e l l run b i o l o g i c a l r e a c t o r , t r e a t i n g l e a c h a t e w i t h the c o r r e c t n u t r i e n t l o a d i n g , c o u l d produce a volume o f s l u d g e e q u a l t o 30% o f the volume o f l e a c h a t e t r e a t e d . The c o n c e n t r a t i o n o f m e t a l s i n the s l u d g e may approach t o x i c l e v e l s . 8) The "Combined" experiment demonstrated t h a t h i g h s t r e n g t h l e a c h a t e and domestic sewage c o u l d be combined and s u c c e s s f u l l y t r e a t e d i n an a e r a t e d lagoon system which has a 20 day d e t e n t i o n t i m e . Even w i t h an i n f l u e n t c o n s i s t i n g o f 20% (v/v) of h i g h s t r e n t h l e a c h a t e , the r e s u l t i n g e f f l u e n t met the P o l l u t i o n C o n t r o l Branch's e f f l u e n t d i s c h a r g e o b j e c t i v e s f o r B O D 5, t o t a l suspended s o l i d s , n u t r i e n t s and m e t a l s . 6-2 Recommendations f o r F u t u r e Research Problems which r e q u i r e f u r t h e r work: 1) The e f f e c t s o f low temperature on a l l a s p e c t s of b i o l o g i c a l t r e a t m e n t o f l e a c h a t e . 2) Treatment o f t h e b i o l o g i c a l s l u d g e produced. P a r t i c u l a r emphasis s h o u l d be p l a c e d on m e t a l removel from t h e s l u d g e o r l o n g term s t a b i l i z a t i o n o f t h e d r i e d s l u d g e . 3) E f f l u e n t p o l i s h i n g , f o l l o w i n g b i o - t r e a t m e n t , t o reduce o r remove any r e s i d u a l p o l l u t a n t s , e s p e c i a l l y m e t a l s . CHAPTER 7 REFERENCES Cameron, R.D., "The E f f e c t s o f S o l i d Waste L a n d f i l l L e a c h a t e s on R e c e i v i n g Water", paper p r e s e n t e d a t the 1975 B r i t i s h Columbia Water and Waste A s s o c i a t i o n C o n f e r e n c e , H a r r i s o n Hot S p r i n g s , B.C., 14 pages, A p r i l , 1975. Hughes, G., e t a l , " P o l l u t i o n o f Ground Water Due t o M u n i c i p a l Dumps", T e c h n i c a l B u l l e t i n No. 42, I n l a n d Waters Branch, Department o f Energy, Mines and Resources, Ottawa, Canada, 1971. Walker, W. H., " I l l i n o i s Ground Water P o l l u t i o n " , J o u r n a l o f American Water Works A s s o c i a t i o n , V o l . 61, 1969, pp. 31-40. C h i a n , E.S.K. and F.B. DeWalle, " S a n i t a r y L a n d f i l l L e a c h a t e s and t h e i r Treatment", J o u r n a l o f E n v i r o n m e n t a l E n g i n e e r i n g D i v i s i o n , P r o c e e d i n g s o f The American S o c i e t y o f C i v i l E n g i n e e r s , V o l . 102, No. EE2, A p r i l 1976. Sawyer, C.N., B a c t e r i a l N u t r i t i o n and S y n t h e s i s , B i o l o g i c a l  Treatment o f Sewage and I n d u s t r i a l Waste, V o l . 1, R e i n h o l d P u b l i s h i n g Company, New York, 1956. Lawrence, A.W. and McCarty, P.L., "A U n i f i e d B a s i s f o r B i o l o g i c a l Treatment D e s i g n and O p e r a t i o n " , J o u r n a l o f S a n i t a r y E n g i n e e r i n g D i v i s i o n , P r o c e e d i n g s o f the American S o c i e t y o f C i v i l E n g i n e e r s , pp. 757-778, June, 1970. M e t c a l f , L. and Eddy, H., Wastewater E n g i n e e r i n g : C o l l e c t i o n , Treatment, D i s p o s a l , M c G r a w - H i l l Book Company, 1972. U l o t h , V.C., " A e r o b i c B i o s t a b i l i z a t i o n o f a H i g h - S t r e n g t h L a n d f i l l L e a c h a t e " , Master o f A p p l i e d S c i e n c e T h e s i s , Department o f C i v i l E n g i n e e r i n g , U n i v e r s i t y o f B r i t i s h Columbia, 110 pages, F e b u r a r y 1976. T a r r e r , A.R. , Grady J r . , C P . , Lim, H.C. , and L.B. Koppel, "Optimal A c t i v a t e d Sludge D e s i g n Under U n c e r t a i n t y " , J o u r n a l o f S a n i t a r y E n g i n e e r i n g D i v i s i o n , P r o c e d i n g s o f the American S o c i e t y o f C i v i l E n g i n e e r i n g , pp. 657-673, June 1976. Cheng, M.H., P a t t e r s o n , J.W., and R.A. Minea r , "Heavy M e t a l Uptake by A c t i v a t e d Sludge", J o u r n a l Water P o l l u t i o n C o n t r o l F e d e r a t i o n , C o l . 47, pp. 362-376, F e b r u a r y 1975. " I n t e r a c t i o n o f Heavy M e t a l s and B i o l o g i c a l Sewage Treatment P r o c e s s e s " , U.S. Department o f H e a l t h , E d u c a t i o n and W e l f a r e , P u b l i c H e a l t h S e r v i c e P u b l i c a t i o n Number 999, WP-22, 1965. * B a r t h , E.F., E t t i n g e r , M.B., S a l o t t o , B.V., and G.N. Dermott, "Summary Report on t h e E f f e c t s o f Heavy M e t a l s on t h e B i o l o g i c a l Treatment P r o c e s s e s " , J o u r n a l Water P o l l u t i o n C o n t r o l F e d e r a t i o n , V o l . 37, pp. 86-96, J a n u a r y 1965. N e u f e l d , R.D. and E.R. Hermann, "Heavy M e t a l Removal By A c c l i m a t e d A c t i v a t e d S l u d g e " , J o u r n a l Water P o l l u t i o n C o n t r o l F e d e r a t i o n , V o l . 47, No. 2, F e b r u a r y 1975, pp.310-329. C a r t e r , J . L . , and R.E. McKinney, " E f f e c t s o f I r o n On A c t i v a t e d Sludge Treatment", J o u r n a l o f t h e E n v i r o n m e n t a l E n g i n e e r i n g D i v i s i o n , p r o c e e d i n g s o f t h e American S o c i e t y o f C i v i l E n g i n e e r s , V o l . 99, No. EE2, A p r i l 1973. Poon, C.P.C. and K.H. B h a y a n i , "Metal T o x i c i t y t o Sewage Organisms", J o u r n a l o f S a n i t a r y E n g i n e e r i n g D i v i s i o n , pp. 161 - 169, V o l . 97, A p r i l 1971. Argo, D.G. and G.L. C u l p , "Heavy M e t a l Removal i n Wastewater Treatment P r o c e s s e s , P a r t 1", Water and Sewage Works, pp 62-65, August 1972. B a r t h , E.F., E n g l i s h , J.N., S a l o t t o , B.V., J a c k s o n , B.N., and M.B. E t t i n g e r , " F i e l d Survey o f Four M u n i c i p a l Wastewater Treatment P l a n t s R e c e i v i n g M e t a l l i c Wastes", J o u r n a l o f Water P o l l u t i o n C o n t r o l F e d e r a t i o n , V o l . 37, No. 8, pp. 1101-1117, August 1965. Coughlan, F.P., and A.E. S p a r r , "Design and E a r l y O p e r a t i n g E x p e r i e n c e o f A c t i v a t e d Sludge P l a n t F o r Combined Treatment o f P u l p , Paper and Domestic Waste", P r o c e e d i n g s o f t h e 16th 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 e r s i t y , E x t . Serv. 109, West L a y a y e t t e , I n d i a n a , page 375, 1961. 85 19. Helmers, E.N., Frame, J.D., Greenberg, A.E., and C.N. Sawyer, " N u t r i t i o n a l Requirements i n the B i o l o g i c a l S t a b i l i z a t i o n o f I n d u s t r i a l Wastes. I l l Treatment With Supplementary N u t r i e n t s " , Sewage and I n d u s t r i a l Wastes, C o l . 24, page 496, 1952. 20. McKinney, R.E., Symons, J.M., Conway, R.A., and E . J . Donovan, "Role o f N i t r o g e n In The A e r o b i c S t a b i l i z a t i o n o f O r g a n i c Wastes i n P o l l u t e d Streams", F i n a l Report o f P r o j e c t E-1438 (C), M a s s a c h u s e t t s , I n s t i t u t e o f Technology, Cambridge, Mass., U.S.A. 21. Greenberg, A.E., K l e i n , G. and W.J. Kaufman, " E f f e c t o f Phosphorus on t h e A c t i v a t e d Sludge P r o c e s s " , Sewage and I n d u s t r i a l Wastes, V o l . 27, Page 277, 1955. 22. H a t t i n g h , W.H.J. , "The N i t r o g e n and Phosphorus Requirements o f M i c r o - o r g a n i s m s In A c t i v a t e d Sludge:, PH.D. T h e s i s , Department o f S o i l S c i e n c e , U n i v e r s i t y o f B r i t i s h Columbia, 143 pages, August 1962. 23. S h e r r a r d , J.H., and E.D. S c h r o e d e r , " S t o i c h i o m e t r y o f I n d u s t r i a l B i o l o g i c a l Wastewater Treatment", J o u r n a l Water P o l l u t i o n C o n t r o l F e d e r a t i o n , V o l . 48, pp.742-747, A p r i l 1976. 24. S i k e s , J.E.G., and G.A. Nieminen, "Economic C o n s i d e r a t i o n s In The S e l e c t i o n o f A B i o l o g i c a l Treatment System", 1975 Environment Improvement C o n f e r e n c e , Canadian P u l p and Paper A s s o c i a t i o n , O c tober 15 - 17, 1975. 25. Cook, E.N. and E.G. F o r e e , " A e r o b i c B i o s t a b i l i z a t i o n o f S a n i t a r y L a n d f i l l L e a c h a t e " , J o u r n a l Water P o l l u t i o n C o n t r o l F e d e r a t i o n , V o l . 46, pp. 380 - 392, F e b r u a r y 1974. 26. B o y l e , W.C., and R.K. Ham, " B i o l o g i c a l T r e a t a b i l i t y o f L a n d f i l l L e a c h a t e " , J o u r n a l Water P o l l u t i o n C o n t r o l F e d e r a t i o n , V o l . 46, No. 5, pp. 860 - 872, May 1974. 27. Upadhyaya, A.K. and L.P. Q u e n t i n , " C h a r a c t e r i z a t i o n and Treatment o f L e a c h a t e - A Case Study", Second Annual Research and D e s i g n C o n f e r e n c e , U n i v e r s i t y o f F l o r i d a , J u l y 21 - 25, 1975. 28. " P o l l u t i o n C o n t r o l O b j e c t i v e s F o r M u n i c i p a l Type Waste D i s c h a r g e s i n B r i t i s h Columbia", Department o f Lands, F o r e s t s , and Water R e s o u r c e s , Water Re s o u r c e s S e r v i c e , V i c t o r i a , B r i t i s h Columbia, September 1975. 86 29. A.P.H.A., A.W.W.A., W.P.C.F., S t a n d a r d Methods F o r  E x a m i n a t i o n o f Water and Wastewater, American P u b l i c H e a l t h A s s o c i a t i o n , I n c . 13th E d i t i o n , 1971. 30. "Methods o f Chemical A n a l y s i s o f Water and Wastes", U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency, Water Q u a l i t y L a b o r a t o r y , C i n c i n n a t i , Ohio, 1971. 31. Newfeld, R.D., G u t i e r r e r , J. and R.A. Novak, " K i n e t i c Model and E q u i l i b r i u m R e l a t i o n s h i p f o r Heavy M e t a l A c c u m u l a t i o n on A c t i v a t e d Sludge", J o u r n a l o f Water P o l l u t i o n C o n t r o l F e d e r a t i o n , C o l . 49, pp. 489 - 498, March 1977. 32. I r v i n e , R.L. and D.J. S c h a e z l e r , " K i n e t i c A n a l y s i s o f Data From B i o l o g i c a l Systems", J o u r n a l o f the S a n i t a r y E n g i n e e r i n g D i v i s i o n , P r o c e e d i n g s o f t h e American S o c i e t y o f C i v i l E n g i n e e r s , C o l . 97, No. SA4, August 1971. CHAPTER 8 APPENDICES APPENDIX A DETERMINATION OF KINETIC PARAMETERS D e t e r m i n a t i o n o f K and K c Note: Symbols d e f i n e d i n Chapter 2 Rate o f S u b s t r a t e ds = S D - S i U t i l i z a t i o n d t 9 c Monod E q u a t i o n ds = K X v S-| d t K s + S 1 R e a r r a n g i n g the Monod E q u a t i o n and d i v i d i n g each s i d e by X v, X v K s ,1 , . 1 = r r ^ (TT ) + d s / d t K "S]_' K X 1 P l o t t i n g ., V v s . — s h o u l d y i e l d a s t r a i g h t l i n e d s / d t w i t h a s l o p e K^ and i n t e r c e p t 1^  K K ' S]_ has been d e f i n e d as 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 s u r r o u n d i n g the m i c r o - o r g a n i s m s . There i s a q u e s t i o n , however, as t o whether S]_ i s t h e mixed l i q u o r BOD 5 ( U l o t h ( 8 ) ) , o r f i l t e r e d BOD 5 ( I r v i n e and S c h a e z l e r ( 3 2 ) ) . The computations a r e l i s t e d i n T a b l e XXVI a t t h e end o f t h i s s e c t i o n and t h e r e s u l t s a r e p l o t t e d i n F i g u r e s 14 and 16. D e t e r m i n a t i o n of Y and A b i o l o g i c a l s o l i d s b a l a n c e y i e l d s the e q u a t i o n : dx _ Y ds d t ~ d t " K d X v R e a r r a n g i n g the above e q u a t i o n : A v A v A p l o t o f dx/dt v s . d s / d t s h o u l d y i e l d a s t r a i g h t l i n e w i t h s l o p e Y and i n t e r c e p t , -Kjj, A l s o ds = S n - S i d t ~ 9-And dx _ X-| - X n d t ~ 9 C Assuming v o l a t i l e suspended s o l i d s c o n c e n t r a t i o n i n the l e a c h a t e f e e d a r e n e g l i g i b l e , X Q = 0, t h e n : dx = Xj d t " 0 C The computations a r e l i s t e d i n T a b l e XXVI and th e r e s u l t s a r e p l o t t e d i n F i g u r e s 15 and 17. 'Pure " C o m b i n a t i o n ' L e a c h a t e " ' E x p t . E x p t . t d 3 Cd * l to 3 t d H- ID H- CU p. CD r—1 CO X 10 1—1 CO X CO rt ft) CD CO rt CD CD CD (D Di Cb Cb CD Qi Di Di l"f 1 H; 1 CD O tr 1 O (D O tr1 O Ch 3 P- 3 CL 3 H- 3 td c; Cd d O 0 O o O H O Hi Ln in cd t d O O o O in in O O O O H H-1 -o to ^ - J U) in CO to to \ D > K .. to i l 1—1 \ • • *• tr1 X cn ID U> H- CO lo CO rt ID in Hi CD B. o O O O < » • • • CO K *> in in CO NJ U) NJ \ co in CO in 3 «.Q td O D in o O o O o o O o O > w Kj Qi o O o o 1 NJ NJ NJ NJ in in in in (A) MIXED LIQUOR B0D 5 Is* B(D-o' A(l) f\ (I) E(I) ,F(0 SLOPE - K s / K * 28500 K-0.75 mg/mgVSS/DAY KB« 21375 mg/LITER INTERCEPT l/K-1.33 K • 0.75 1 1 1 1 1 1 1— 0.1 0.2 03 0.4 0.5 0.6 07 l / S M f 1 0 ' V m g / L I T E R FIGURE 14: DETERMINATION OF K AND Ks US I NO; LEACHATE" EXPERIMENT e CO C O > E io A 9 H 8 H 7 H 6 H 6H 4 A CO < v . H 5 3 2 H (B) FILTERED B0D 5 A(l) B(l) °F(I) SLOPE « Ks / K • 15.0 K«0J32 mg/ mgVSS/DAY Ks- 1.98 mg / LITER INTERCEPT l/K« 7.6 .*. K- 0.132 10 20 30 40 50 - T " 60 l / S F , IO"3 /mg/LITER 70 ' i IXED LIQUOR H O D r AND I I I lERfD R O D r DATA - 'TURi: 92 Q06H 005 t Q04 D 003 > X 002 X OOM -001 (A) MIXED LIQUOR B0D 5 C(0 AO) Bfl) ^ E(l) F(l) \ L A ^ 1 i -OCD SLOPE = Y = 0.525 mgVSS / mg — T — 0.02 0.04 I — 0.06 0.0 B - i — o.io 0.12 K= 0.0025 DAY"' A S / A T / X v , m g / m g V S S / D A Y 006 005 _ 0.04 r ° 003 H X* 0.02 < 3 X < OOI (B) FILTERED B0D 5 cm AO) B(I) DM ECO' SLOPE = Y = 0.434 mgVSS/ mg 002 [ 0.04 I 006 ~ I — ooe o.io 012 K a 0.0025 DAY"*' A S / A T / X y , mg/mgVSS/DAY FIGURE 15: DETERMINATION OF Y AND K r f FOR "PURE LEACHATE" EXPERIfENT USING MIXED LIQUOR BOD,. AND FILTERED BOD5 DATA 25-^ Q E CO in > E CO <1 < X 15-1 (A) MIXED LIQUOR B 0 D 5 SLOPE = Ks/K = 800 K = 0.174 mg/mgVSS/DAY Ks = 139 mg/LITRE S L O P E • K t / K • 8 0 0 K M I39mg/I C (2), INTERCEPT i l / K • 5.78 K « 0.174 25-^ ° 15 E CO > E to < J S< 5 (B) F I L T E R E D B 0 D 5 SLOPE = Ks/K = 2| K = 0.172 mg/mgVSS/DAY Ks = 3.61 mg/LITRE SLOPED K i / K i 21 .C (2 ) E ( 2 ) ^ . ^ ^ 0 ( 2 ) V(2) K M 3.61 • B(2) INTERCEPT • l /K « 8.80 . ' . K • 0.172 10 14 100 200 300 400 I/SM ,10-3 / m g / L I T E R l / S F , l0- 3 / m g / L I T E R FIGURE 16: DETERMINATION OF K AND K g USING MIXED LIQUOR B0D 5 AND FILTERED B0D 5 DATA - "COMBINATION** U5 EXPERIMENT 94 0.06 0.05 H _ 004 H o O03 -{ 0 0 2 -i 001 X o -Q0I (B) FILTERED B0D 5 D(l) E(l) SLOPE= Y = 0.438 mgVSS / mg 0 0 2 0 0 4 I 0 0 6 O08 1 OX) 0J2 - K= 0.0025 DAY"' A S / A T / X v , mg /mgVSS/DAY F(l) FIGURE 17: DETERMINATION OF Y AND K d FOR "COMBINATION" EXPERIMENT USING MIXED LIQUOR BOD 5 AND FILTERED BOD5 DATA 

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