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The affect of anaerobic volume reduction on the University of Cape Town (UCT) biological phosphorus removal.. 1990

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THE AFFECT OF ANAEROBIC VOLUME REDUCTION ON THE UNIVERSITY OF CAPE TOWN (UCT) BIOLOGICAL PHOSPHORUS REMOVAL PROCESS BY NELSON PAUL LEE B.Sc.(Chem. Eng.) 1979, U n i v e r s i t y o f A l b e r t a Edmonton, A l b e r t a A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE IN THE FACULTY OF GRADUATE STUDIES (Department of C i v i l Engineering) We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard UNIVERSITY OF BRITISH COLUMBIA 1990 NELSON PAUL LEE, March 1990 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of (?J 1/< I- 2xO<^ A £ g £ / 0 The University of British Columbia Vancouver, Canada Date 9 0 - 0 3 - 3 0 DE-6 (2/88) ii Abstract The objective of this research was to optimize the bio-P process as applied to a weak sewage with respect to HRT in each of the process zones. This goal was to be achieved by changing the HRT of the various zones with all other operating characteristics being held constant. The experimental work during this study involved two initially identical process trains operated in the University of Cape Town (UCT) mode. The aerobic zones of both trains were divided into four equal sized complete-mix cells to allow observations of phosphate uptake and poly-0-hydroxyalkanoate (PHA) consumption under aerobic conditions. After steady-state was established, the anaerobic HRT was reduced to 50% of the original value in the experimental module by reducing the anaerobic reactor volume. At the same time, the mixed liquor of both trains was drained, mixed and reapportioned to the two processes, thereby assuring equivalent starting conditions. Results of this study showed that both processes performed identically prior to the anaerobic HRT change. After the anaerobic HRT change, there was a forty day period where P removal and effluent P were the same in both process trains. This was so, even though the anaerobic P release was considerably less in the experimental module. Subsequently, a change in influent sewage type corresponded to a change in P removal and effluent P in the two process trains. An examination of the process parameters showed that the anoxic zone of the experimental module, after the anaerobic HRT change and the sewage change, consistently removed less P or released more P than iii in the control module. As a result, the control module out-performed the experimental module. Batch tests and tests to better characterize the influent sewage were then conducted in an attempt to determine the reasons for the different P removal characteristics. Under the test conditions, it appeared that the original anaerobic HRT was excessive. This was preferable to an insufficient anaerobic HRT, such as in the experimental module, however. The anoxic zone may have been too large, too small or just right for optimum P removal depending on the influent sewage characteristics. Optimizing the bio- P process by reducing the aerobic zone HRT appeared to have the greatest potential. iv Table of Contents Page Abstract i i Table of Contents iv L i s t of Tables v i i L i s t of Figures v i i i Acknowledgements x i Chapter 1. Introduction 1 Chapter 2. Background 2 2.1. L i t e r a t u r e Review 2 2.1.1. Summary 29 2.2. Hypotheses 30 2.3. Objectives 31 Chapter 3. Experimental Procedures 3 3 3.1. Process Description 3 3 3.1.1. Physical Apparatus C h a r a c t e r i s t i c s 3 3 3.1.2. Operational C h a r a c t e r i s t i c s 41 3.1.3. Batch Tests 4 2 3.2. Sampling and A n a l y t i c a l Methods 43 3.2.1. Flow-Through Process 4 3 3.2.2. Batch Test 48 3.3. Feed Source and Composition 4 9 3.3.1. Raw Sewage 49 3.3.2. Acetate/Propionate Chemicals 53 V 3.3.3. C o l l e c t i o n and Storage of Sewage 55 3.3.4. Mixed Liquor and Start-Up 5 5 Chapter 4. Results 57 4.1. Acclimation and Debugging, PP1 59 4.2. Base l i n e Conditions 62 4.3. E f f e c t of Anaerobic HRT Change 71 4.3.1. R2 Period 71 4.3.2. PP2 Period 74 4.4. Ad d i t i o n a l Tests 78 4.4.1. Daily Testing .. .. 8 0 4.4.2. Batch Tests 8 5 4.4.3. Mixed Sludges Test 92 Chapter 5. Discussion of Results 9 4 5.1. Anomalies 94 5.1.1. Anomaly 1 94 5.1.2. Anomaly 2 98 5.1.3. Anomaly 3 99 5.2. Bio-P Mechanisms 100 5.3. E f f e c t of Anoxic HRT '. 116 5.4. E f f e c t of Anaerobic HRT 120 5.5 E f f e c t of Aerobic HRT 12 5 5.6 Comparison with Others 13 0 Chapter 6. Conclusions 1 3 6 Chapter 7. Recommendations 1 3 8 Chapter 8. References Chapter 9. Appendices v i i L i s t of Tables Table T i t l e Page 3.1. Equipment S p e c i f i c a t i o n s 36 3.2. Operational C h a r a c t e r i s t i c s 36 3.3. Weekly Sampling Schedule 44 3.4. Batch Test Sampling Schedule 50 3.5. Target Feed C h a r a c t e r i s t i c s 51 3.6. Richmond Feed C h a r a c t e r i s t i c s 51 3.7. P i l o t - P l a n t Feed Charact e r i s t i c s 54 4.1. Experimental Periods 58 4.2. T y p i c a l Feed C h a r a c t e r i s t i c s 58 4.3. Summary of Feed, Anaerobic, and C l a r i f i e r Underflow C h a r a c t e r i s t i c s f o r the Batch Tests .... 87 4.4. Phosphate Mass Balances Before and A f t e r Mixing Sludges 87 5.1. Ratios of BOD5 to COD for Richmond and P i l o t - P l a n t Sewages 13 3 viii L i s t of Figures Figure T i t l e P a g e 2.1. Four-Stage Bardenpho Process 4 2.2. Three-Stage Phoredox Process 4 2.3. UCT Process . . . 4 2.4. A/0 Process 4 2.5. A20 Process 4 2.6. E f f e c t of Acetate and Nit r a t e on the Phosphate Release P r o f i l e 10 2.7. Phosphate Release and Uptake Under Anaerobic and Aerobic Conditions f o r Various Acetate Additions.. 10 2.8. E f f e c t of Various Substrates on Phosphate Release Under Anaerobic Conditions 15 2.9. E f f e c t of Acetate Addition on Phosphate Release and Uptake Under Aerobic Conditions 15 2.10. E f f e c t of Acetate Addition on Phosphate Release and Uptake Under Anoxic Conditions 18 2.11. Phosphate Uptake and Release Under Anoxic and Anaerobic Conditions 18 3.1. Experimental UCT Process 3 4 3.2. Experimental Process Schematic i n P r o f i l e 34 3.3. A i r System Schematic 4 0 3.4. Batch Test Apparatus 40 4.1. T o t a l Module Mixed Liquor Suspended Solids 60 4.2. E f f l u e n t Ortho-Phosphate as P 60 4.3. Anaerobic Zone Phosphate Mass Release 61 4.4. Influent COD (mg/L) 61 4.5. Influent Total Phosphate as P (mg/L) 6 3 i x 4.6. Phosphate Removal 63 4 . 7 . Anoxic Phosphate Mass Release or Uptake 65 4 . 8 . T o t a l Aerobic Zone Phosphate Mass Uptake 65 4 . 9 . F i l t e r e d E f f l u e n t Nitrate Plus N i t r i t e 68 4 . 1 0 . Phosphate P r o f i l e s for: a - J u l y 2 7 , t=31 d 68 b - Oct. 8, t=104 d 69 c - Oct. 12, t=108 d 69 4.11. Percent Phosphate as P i n Dry Solids 70 4.12. Influent Total Kjedahl Nitrogen (mg/L) 7 0 4.13. F i l t e r e d Influent Ammonia 7 2 4.14. Influent Total and Soluble 5 Day BOD 7 2 4.15. Influent Total Organic Carbon 76 4.16. Influent V o l a t i l e Fatty Acid Concentration 7 6 4.17. Phosphate P r o f i l e f o r November 23 t=150 d 79 4.18. Phosphate P r o f i l e s f o r : a - March 22 t=270 d 79 b - March 25 t=273 d 79 4.19. To t a l and Soluble 5 Day BOD 81 4.20. To t a l and Soluble COD 81 4.21. Influent Total Organic Carbon 82 4.22. Phosphate Removal 82 4.23. Influent V o l a t i l e Fatty Acids 8 4 4 A aerobic E f f l u e n t V o l a t i l e Fatty Acids X 4.25. Batch Test Results: a - #1 Control Module 8 8 b - #1 Experimental Module 8 8 c - #2 Control Module 89 d - #2 Experimental Module 89 5.1. Anaerobic E f f l u e n t V o l a t i l e Fatty Acid Concentrations i n the Control and Experimental Modules 96 5.2. Anaerobic and Anaerobic+Anoxic Phosphate Release as P vs E f f l u e n t Phosphate as P-Control Module ... 102 5.3. Phosphate Mass Uptake Rate as P vs I n l e t Phosphate Concentration as P - Both Modules 109 5.4. PHA Mass Storage or Consumption i n the Anaerobic, Anoxic and Aerobic Zones 110 5.5. Anoxic zone PHA Storage or Consumption and Phosphate Release or Uptake 112 5.6. Aerobic Zone PHA Mass Consumption and Phosphate Mass Uptake as P 113 5.7. Anaerobic Zone PHA Mass Storage and Phosphate Mass Release 114 5.8. Modified UCT Process 119 5.9. Soluble Biochemical Oxygen Demand P r o f i l e 127 xi Acknowledgements I would like to thank Dr. Oldham for his advice, insight and suggestions and also for arranging the financial support throughout the research period. Special thanks to Susan Liptak, Paula Parkinson and Romy So who provided invaluable tips and training. Their patience was also appreciated. Thanks also go to Dr. Mavinic for reviewing the thesis. I would also like to thank fellow students Yves Comeau, Ramanathan Manoharan and Neal Carley who helped me get started and kept me going. Their cheerful, enthusiastic help will not be forgotten. A final thanks to Fred Koch who happily spent many hours discussing any aspects of biological nutrient removal processes with me. The pilot-plant would never be the same without Fred. 1 Chapter 1. Introduction Excess b i o l o g i c a l phosphorus removal (bio-P) i s an e f f i c i e n t method of removing phosphorus (P) from municipal wastewaters. Many of the researchers who have demonstrated t h i s point worked with wastewater which was high i n organic content (Barnard (1984, Gerber et a l . (1987)). Consequently, most of the design c r i t e r i a f or such treatment f a c i l i t i e s are more i d e a l l y suited to the treatment of strong wastewater. Since much of Canadian municipal wastewater i s considerably weaker, there i s j u s t i f i c a t i o n f or experimentally investigating the impacts of the process hydraulic retention time (HRT) on P removal and ef f l u e n t P l e v e l s . S p e c i f i c a l l y , an experimental study into the e f f e c t s of anaerobic (An) HRT, anoxic (Ax) HRT and aerobic (Ae) HRT on P removal and e f f l u e n t P l e v e l s may help designers of bio-P processes optimize t h e i r designs for the t y p i c a l l y weak Canadian municipal wastewaters. In t h i s thesis, the research which led to the formation of the hypothesis upon which t h i s project was founded was reviewed. The physical process description, sampling procedures, operational techniques and feed source and desc r i p t i o n are reported. The r e s u l t s of the experiments are presented, followed by a discussion of the main points. The findings are presented i n the Conclusion and Recommendations sections. 2 Chapter 2. Background 2.1 Li t e r a t u r e Review The l i t e r a t u r e reviewed here was selected for i t s relevance to t h i s p a r t i c u l a r project, only and i s thus l i m i t e d i n scope. Li t e r a t u r e i s presented to form the t h e o r e t i c a l basis upon which t h i s research was conceived and to support the findings of t h i s project. Srinath et a l . (1959) and Alarcon (1961) were the f i r s t to report excess b i o l o g i c a l phosphorus (bio-P) removal. Srinath et a l . noted that P uptake might be related to the s o l i d s concentration. Alarcon reported that P uptake might be a function of aeration i n t e n s i t y . Levin and Shapiro (1965) were the f i r s t to propose a biochemical basis for bio-P removal. They demonstrated the i n h i b i t o r y e f f e c t s of 2, 4-dinitrophenol on aerobic uptake. They also showed that no improvement i n P uptake occurred when the pH was maintained i n the range where calcium phosphate forms. Thus, they i l l u s t r a t e d that the bio-P mechanism was p r i n c i p a l l y b i o l o g i c a l and not chemical. They noted that substrates such as succinate and glucose promoted P uptake i n batch experiments. In these experiments, sludge from a short sludge age process was aerated with and without substrate addition. They also noted that the degree of P uptake increased 3 with increasing aeration rate up to a plateau, a f t e r which further increases i n aeration had no a f f e c t on P uptake. Shapiro et a l . (1967) subjected a batch sample of sludge to a l t e r n a t i n g anaerobic and aerobic conditions. P was released from the mixed liq u o r s o l i d s under anaerobic conditions but disappeared from solution under aerobic conditions. This i l l u s t r a t e d the r e v e r s i b i l i t y of the bio-P process. This r e v e r s i b l e nature was also confirmed by Wells (1969) . Fuhs and Chen (1975) investigated the e f f e c t of the anaerobic-aerobic sequence on the microbiological nature of the sludge. They found that a laboratory-scale anaerobic-aerobic process which was not removing excess P contained few organisms capable of s t o r i n g poly-phosphate (poly-P). The poly-P storing organisms were i d e n t i f i e d as belonging to the Acinetobacter genus, and were obligate aerobes. In h i s investigations of the Bardenpho four-reactor n i t r i f i c a t i o n - d e n i t r i f i c a t i o n process, as shown i n Figure 2.1, Barnard (1976) noted that P concentrations i n the t h i r d reactor were very high and almost n i l l i n the subsequent aerobic reactor. He noted that the high-rate plug flow processes i n l i t e r a t u r e reports of excess bio-P removal also released P i n the non-aerated zone and took up P i n the subsequent aerobic zone. Barnard proposed that the anaerobic P release was the key PRIMARY MOONOunr ANOXIC AiBOOC ANOXIC neAfifWTION R E A C T O R R O C T O B R E A C T O R R E A C T O R tMxeo uouon R C C Y C L E Figure 2.1 4-Stage Bardenpho Process AMAEROeiC R E A C T O R S R E A C T O R S CLARIFIER PRIMARY SECONDARY AMCDOC AEROBIC ANOXIC REACTOfl REACTOR REACTOR MIXED U O U O R R E C Y C L E SLUOQE RECYCLE Figure 2.4 A / O Process Figure 2.2 Phoredox or Modified Bardenpho Process ANAEROBIC ANOXIC AEROBIC REACTOfB REACTORS REACTORS CLARIFIER INTERNAL RECYCLE ANAEROBIC REACTOR ANOXIC REACTOR AEROBIC REACTOR MIXED LIQUOR RECYCLE SLUDGE RECYCLE Figure 2.5 A 2 / 0 Process Figure 2.3 UCT Process to the bio-P removal mechanism. He suggested a modification to the Bardenpho process which became known as the Modified Bardenpho process or the Phoredox process (Figure 2.2). This modification involved the addition of an anaerobic zone preceding the four Bardenpho reactors. The i n f l u e n t and the sludge recycle were both fed to the anaerobic zone. Barnard also pointed out the adverse e f f e c t of n i t r a t e recycled with the sludge to the anaerobic zone. This was also demonstrated by Nic h o l l s (1978), who showed that the anaerobic P release was connected to the excess bio-P removal. To solve the problem of n i t r a t e recycle to the anaerobic zone, Rabinowitz and Marais (1980) suggested a modification to the Phoredox process shown i n Figure 2.3 which became known as the UCT process. The secondary anoxic and reaeration reactors were l e f t out. The key differences however were the return of sludge to the anoxic zone rather than to the anaerobic zone and the addition of a recycle from the anoxic zone to the anaerobic zone. Adjusting the various recycle rates and properly s i z i n g the anoxic reactor f o r a given'sewage could ensure that no n i t r a t e would be recycled to the anaerobic zone. A i r Products and Chemicals, Inc. developed a b i o l o g i c a l process shown i n Figure 2.4 c a l l e d the A/O Process. I t was e s s e n t i a l l y a high rate compartmentalized activated sludge process with an unaerated (anaerobic) zone preceding the aerated 6 (oxic) zone hence the name A/0. A modification to incorporate n i t r i f i c a t i o n and d e n i t r i f i c a t i o n — r e f e r r e d to here as the A20 process for improved c l a r i f i c a t i o n — i s shown i n Figure 2.5. I t was e s s e n t i a l l y a high rate compartmentalized, 3 stage Phoredox process. N i c h o l l s and Osborn (1979) developed a biochemical model to explain bio-P removal. Two key points of t h e i r model were: 1. that poly-P could be used to provide energy for bio-P organisms r e s u l t i n g i n P release; 2. that the a b i l i t y to store carbon i n the form of poly-/3- hydroxybutyrate (PHB) was important to the s u r v i v a l of aerobic organisms i n the anaerobic zone. They also pointed out the pote n t i a l benefits of adding v o l a t i l e f a t t y acids (VFA's), such as found i n digester supernatant, to the anaerobic zone. Rensink (1981) t r i e d to explain how the presence of an anaerobic zone would favour the p r o l i f e r a t i o n of poly-P storing organisms. In h i s hypothesis, he stated the following: 1. Poly-P storing organisms also stored carbon under anaerobic conditions i n the form of PHB. Short chain VFA's were the source of t h i s carbon; 2. The energy to form PHB was generated by Poly-P hydrolysis to ortho-P giving r i s e to P release; 3. The stored carbon would give the poly-P stor i n g organisms an advantage i n the aerobic zone. 7 Rensink found that the number of poly-P storing organisms in the sludge increased when an aerobic process was converted to an anaerobic-aerobic process with acetate addition to the anaerobic zone. During a s i x week period the process went from l i t t l e P release or excess P removal and l i t t l e acetate consumption to complete acetate consumption with P release and excess P removal. Hence, Rensink demonstrated the association of poly-P organisms with acetate consumption and P release. Barnard (1984) t r i e d to c l a s s i f y by causative conditions the release of P from the mixed l i q u o r s o l i d s . He postulated that some phosphate might be released as a r e s u l t of acetate uptake by the biomass which would i n turn be used as energy for the uptake of phosphates. He termed t h i s "primary release". Phosphate which may be released due to carbon dioxide or other factors and more importantly not associated with any form of energy intake which would be available for l a t e r phosphate uptake was termed "secondary release". He continued to speculate that i f a s u f f i c i e n t amount of the t o t a l phosphate release (in the anaerobic phase of a bio-P process) was "primary release", then s u f f i c i e n t energy would be a v a i l a b l e f o r the uptake of phosphate, including the secondary release, i n the subsequent aerobic zone . On the other hand, i f most of the release was secondary release, then the phosphate uptake i n the aerobic phase would be incomplete. The p o t e n t i a l s i g n i f i c a n c e of h i s postulation was that a 8 b i o l o g i c a l phosphorus removal process could be optimized or at lea s t improved by ensuring that most of the release was of the primary type. Stated s l i g h t l y d i f f e r e n t l y , improvement could be achieved by avoiding secondary type release. Barnard was mainly thinking about anaerobic phosphate release. Work by Comeau 1984 and Gerber et a l . 1986 showed that anoxic phase phosphate release also can take place. A s i g n i f i c a n t f r a c t i o n of t h i s anoxic P release may be secondary release, hence further opportunity for improvement. Barnard also mentioned that subsequent aerobic phase phosphate uptake would take place rap i d l y i f most of the (anaerobic) phosphate release was of the primary type. Conversely, uptake would proceed more slowly i f much of the release was of the secondary type. Wentzel et a l . (1984) explained the phosphate release pattern i n a d i f f e r e n t way. 1. Readily biodegradable COD i s converted to lower f a t t y acids by non-poly-P heterotrophs i n the anaerobic zone; 2. Poly-P bacteria sequester these f a t t y acids by u t i l i z i n g the energy from the hydrolysis of poly-P; 3. The conversion of COD i s rate l i m i t i n g . Therefore any lower f a t t y acids i n i t i a l l y present i n the feed would give r i s e to rapid phosphate release. Fatty acids produced by conversion (at a slower rate) would give r i s e to 9 slower phosphate release. In other words, although they did not say so, t h e i r conclusions indicated that the slow release would not be detrimental to phosphorus removal. In h i s attempt to develop and support a biochemical model for b i o l o g i c a l phosphorus removal, Comeau (1984) demonstrated a number of related points. F i r s t he showed that phosphate was released a f t e r acetate was added to sludge under unaerated conditions. The release appeared to be i n two parts, an i n i t i a l rapid phosphate release in the presence of acetate followed by a slower release a f t e r the acetate had been consumed. The i n i t i a l high phosphate release rate was independent of the concentration of acetate added. Adding more acetate only extended the duration of P release. The subsequent slow phosphate release rate also appeared to be s i m i l a r for each run. This i s i l l u s t r a t e d i n Figure 2.6. Comeau's batch tests simulated an anaerobic-anoxic sequence. This was accomplished by introducing n i t r a t e plus n i t r i t e to a biomass a f t e r several hours under anaerobic conditions. On the basis of h i s findings i t seems that there may be a considerable amount of secondary release. The amount would depend on the acetate (or other simple carbon) addition i n the anaerobic zone, the n i t r a t e plus n i t r i t e load to the anoxic zone and the HRT of each zone. 0.5 0.4 0.3 0.2 0.1 a 0.0 mM ACETATE + 0.5 mM ACETATE o 1.0 mM ACETATE 0.0 »- Figure 2.6. Effect of Acetate and Nitrate on the Phosphate Release Profile. After Comeau (1984). 120 T 110 - 100 - 90- 5r 80- O) £. 70- O -P  60 - i H- 50-cc o 40- 30 - 20- 10 - 0 4 0 ACETATE ADDITIONS o CONTROL + 25mgCOD/L o 50 mg COD/L 75 mg COD/L 100 mg COD/L TIME (hours) Figure 2.7. Phosphate Release and Uptake Under Anaerobic and Aerobic Conditions for Various Acetate Additions. After Rabinowitz (1985). 11 Rabinowitz (1985) found the same high i n i t i a l phosphate release rate followed by a low release rate type pattern as Comeau (1984). In his batch t e s t s , acetate was added i n s i x d i f f e r e n t concentrations to sludge kept under unaerated conditions but spiked with n i t r a t e . Like Comeau's findings, the i n i t i a l phosphate release rate was the same for a l l dosages and the subsequent lower phosphate release rates were also very s i m i l a r for a l l dosages. In batch t e s t s , Rabinowitz also aerated a biomass previously under anaerobic conditions to simulate an anaerobic - aerobic sequence . Five runs with d i f f e r e n t acetate concentrations were studied. This time the sludge was d e n i t r i f i e d p r i o r to acetate addition. Again the f a m i l i a r pattern of rapid phosphate release at a rate independent of acetate concentration followed by a slow release once a l l acetate had disappeared had emerged. When the a i r was turned on, phosphate was taken up at a high rate i n i t i a l l y followed by a lower rate. When l i t t l e acetate was added, some re-release of phosphate took place a f t e r several hours of aeration. On the other hand, when excess acetate was added, some lag time existed p r i o r to the onset of rapid phosphate uptake. In these cases some residual acetate remained when the a i r was turned on as seen i n Figure 2.7. I t i s in t e r e s t i n g to note that a maximum phosphate release l i m i t existed, a f t e r which a higher acetate addition did not 12 r e s u l t i n more phosphate release. In fact, when acetate was added i n excess, net o v e r a l l phosphate uptake a f t e r about f i v e hours of aeration was less than when the l i m i t was not exceeded. Rabinowitz postulated that when high concentrations of acetate were added to the anaerobic zone, remaining acetate not consumed there also stimulated P release under aerobic conditions. This additional P release delayed the onset of P uptake and prolonged the P uptake period In a series of batch t e s t s , Rabinowitz also added a v a r i e t y of short chain f a t t y acids to two d i f f e r e n t sludges: one ex h i b i t i n g marginal enhanced phosphate removal, the other quite considerable P removal. He found that not only did acetate and propionate r e s u l t i n more anaerobic phosphate release but that the amount of release depended on the type of sludge used. The sludge taken from the plant which was exhi b i t i n g enhanced phosphate removal released more phosphate and did so at a higher rate than the other sludge. One explanation would be that there were more of the bio-P type organisms established i n the one sludge enabling them to release more phosphate more rapid l y . He suggested %P of the sludge would indicate the degree to which a sludge would exhi b i t the enhanced phosphate removal phenomena. Rabinowitz found a good c o r r e l a t i o n between the amount of substrate u t i l i z e d and the amount of phosphate released. He reported values of 0 . 7 5 mg P/mg COD or 0.91 mg P/mg HAc. The rate of short chain f a t t y acid (SCFA) u t i l i z a t i o n i n Rabinowitz' 13 experiments was t y p i c a l l y i n the order of 1 mg/L/min. Comeau et a l . (1985) and Comeau et a l . (1986) i n t h e i r d escription of a biochemical model for enhanced b i o l o g i c a l phosphorus removal promoted the ideas that: 1. Phosphate can be stored as poly-phosphate; 2. The poly-phosphate can be used as a source of energy for acetate storage as poly-/3-hydroxybutyrate, (PHB) ; 3. These stores of carbon could subsequently be consumed to provide the energy for phosphate accumulation as poly- phosphate. One of the key points of the papers was the postulation that the r o l e of the anaerobic zone of a bio-P process i s to maximize carbon storage. They pointed out that t h i s could be enhanced by minimizing oxygen and oxidized nitrogen addition, by maximizing simple carbon substrate addition and also by minimizing H2S and C02 gas production. These gases both tend to cause phosphate release but without the associated carbon storage. This l a s t type of phosphate release can be grouped into the term "secondary release" since i t would not lead to phosphate uptake i n a subsequent anoxic or aerobic zone. Gerber et a l . (1986) performed a series of batch tests i n which a v a r i e t y of short chain f a t t y acids (SCFA) were added under anaerobic conditions to sludges which exhibited enhanced b i o l o g i c a l phosphorus removal. Like Rabinowitz, they found that d i f f e r e n t substrates invoked d i f f e r e n t phosphate release 14 patterns. Acetic acid and propionic acid had the highest phosphate release rates. By subsequently aerating these sludges they found that the sludges with acetic and propionic acid additions also had the highest phosphate uptake rates. Figure 2.8 i l l u s t r a t e s these findings for acetic acid. They also demonstrated, as Rabinowitz had, that i n an excess substrate condition i n an anaerobic zone, there was a l i m i t to the t o t a l amount of phosphate which could be released for a given sludge. In a paper which attempted to modify and extend the biochemical model proposed by Comeau et a l . (1985), Wentzel et a l . (1986) presented a summary of the events which were observed to take place i n a b i o l o g i c a l phosphorus removal plant and which were consistent with t h e i r model. The two models d i f f e r e d mainly i n t h e i r explanation of the metabolic pathways involved i n the enhanced b i o l o g i c a l phosphorus removal phenomena but s t i l l predicted e s s e n t i a l l y the same behaviour i n each of the anaerobic, anoxic and aerobic phases. In b r i e f , they stated the following: I. Anaerobic conditions: 1. PHB i s stored by cleaving stored poly-P i n the presence of acetate; 100 at £ U) CO LL) I- 2 O) £. CL 6 I H OC O oi E. C\J Q o o m to LU I— CC h- O) CO D CO o z < CD CC O a ORTHO-PHOSPHATE • NITRATE o ORGANIC SUBSTRATE Figure 4 6 TIME (h) 0 2.8. Effect of Various Substrates on Phosphate Release Under Anaerobic Conditions. After Gerber et al. (1986). 50 TIME (min) Figure 2.9. Effect of Acetate Addition on Phosphate Release and Uptake Under Aerobic Conditions. After Gerber et al. (1987). 2. P release due to the cleavage of stored poly-P for maintenance energy occurs i n the absence of acetate whether or not PHB i s present. They r e f e r to t h i s as secondary release which does not give r i s e to subsequent P uptake. I I . Anoxic conditions: 1. When PHB i s present but acetate i s not, such as i n the primary anoxic zone of a Bardenpho process or the anoxic zone of a UCT or A/0 process, then there e x i s t s two p o s s i b i l i t i e s : a) Acinetobacter not able to u t i l i z e n i t r a t e (and/or n i t r i t e ) react as i n 1-2; b) Acinetobacter able to use n i t r a t e (and/or n i t r i t e ) w i l l accumulate poly-P. 2. When neither PHB or acetate i s present then: a) Acinetobacter able to use n i t r a t e w i l l u t i l i z e substrate generated by the death of Acinetobacter spp. P release w i l l be observed proportional to the protoplasm mass of dead organisms; b) Acinetobacter not able to u t i l i z e n i t r a t e w i l l react as i n 1-2. II I . Aerobic conditions: 1. I f PHB i s present but acetate i s not, then poly-P accumulation w i l l take place. This takes place i n the main aeration basins of Bardenpho, UCT and A/0, A20 systems; 2. I f PHB and acetate are both absent, then Acinetobacter w i l l react as i n II-2-a. The authors made reference to only Acinetobacter spp., but i t may be possible to extend t h e i r reasoning to any other bio-P type organisms. Also, other SCFA may induce s i m i l a r reactions as acetate. Gerber et a l . (1987) demonstrated the e f f e c t of adding acetate to sludges taken from the anaerobic basin of a bio-P process and then subjecting them to aerobic and anoxic conditions. In both cases, the acetate was added at various times a f t e r the onset of aerobic or anoxic phosphate uptake. This i s i l l u s t r a t e d i n Figures 2.9 and 2.10 for a delay of about 100 minutes. They found that phosphate release took place as soon as the acetate was added, that phosphate release continued u n t i l a l l the acetate was consumed and that phosphate uptake resumed a f t e r the disappearance of acetate. As a r e s u l t of t h e i r findings, the authors cautioned against the addition of excessive amounts of short-chain f a t t y acids or any other condition which may r e s u l t i n these acids entering eit h e r the anoxic or aerobic zones. Comeau et a l . (1987) provided further evidence that short- chain f a t t y acids (SCFA) and t h e i r s a l t s such as acetate are stored under anaerobic conditions as PHB. Furthermore, poly-/3- hydroxyvalerate (PHV) was also found to be a s i g n i f i c a n t storage product depending on the chemical structure of the SCFA's added. I f acetate alone was added, PHB was the primary storage product. Combinations of acetate and propionate led to PHV as the primary storage product with some amount of PHB also stored. 130 TIME (min) Figure 2.10. Effect of Acetate Addition on Phosphate Release and Uptake Under Anoxic Conditions. After Gerber et al. (1987). TIME (h) Figure 2.11. Phosphate Uptake and Release Under Anoxic and Anaerobic Conditions. After Gerber e ta l . (1986). 19 They also demonstrated very c l e a r l y the re l a t i o n s h i p between carbon storage as PHB and/or PHV and phosphate release - both showing the fast-slow P release pattern - under anaerobic conditions and the phosphate uptake and PHB and/or PHV consumption under aerobic conditions. I t i s i n t e r e s t i n g to note that during the slow phosphate release period, at l e a s t some carbon storage may have taken place meaning that the so-called "secondary release" period may not be e n t i r e l y detrimental to the bio-P process. In a preliminary note, Lotter (1987) appeared to concur with the findings that PHB was stored under anaerobic conditions to be used i n the subsequent aerobic zone as the carbon for metabolism. She also noted the role that PHB played i n the enhanced phosphorus removal process. Manoharan (1988) studied the e f f e c t s of d i f f e r e n t dosages of a v a r i e t y of SCFA's to a b i o l o g i c a l phosphorus removal process operated i n a continuous mode. A series of complete-mix reactors i n the UCT configuration without the i n t e r n a l recycle was operated at an SRT of 20 days. Anaerobic, anoxic and aerobic HRT's were 1.25 hours, 1.5 hours and 4.0 hours respectively based on inf l u e n t plus recycled flows f o r 1:1 recycle r a t i o s . He also operated a short SRT, short HRT non-bio-P type process i n p a r a l l e l i n order to measure the "r e a d i l y 20 biodegradable" f r a c t i o n of the influent COD. Acetate, propionate, butyrate and glucose were added i n separate experiments to acclimated sludges s t a r t i n g at l e v e l s of 25 mg/L as COD i n the anaerobic reactor. This dosage was successively cut back by 5 mg/L steps a f t e r steady state was reached. The feed used was characterized as a weak domestic sewage and was cont r o l l e d to an influent COD value of about 270 mg/L including the SCFA addition. He also found the feed to be generally free of VFA's. On the other hand, he found the feed to have a 2 0-25% r e a d i l y biodegradable f r a c t i o n . Manoharan found acetate to be more e f f e c t i v e i n enhancing P removal than propionate when measured on a COD basis. When measured as ac e t i c acid equivalents he found a l l chemicals to have a s i m i l a r e f f e c t . Throughout the entir e study, regardless of the chemical dosage, Manoharan never detected VFA's i n the complete-mix anaerobic reactor, suggesting that the rapid P release phase was le s s than the anaerobic HRT. In other words, some secondary release could have been taking place. S i m i l a r l y for the anoxic zone, he never detected NOx, suggesting that some secondary release of P could take place there. Less phosphate was released and subsequently taken up i n the anaerobic and anoxic/aerobic zones respectively as the chemical dose was decreased. This i s i n good agreement with the batch r e s u l t s of Rabinowitz (1985) and Comeau (1984). Wentzel et a l . (1984) noted that a l i n e a r r e l a t i o n s h i p existed between the phosphate released i n the anaerobic reactor and the phosphate taken up i n the anoxic and/or aerobic reactors. They found that at steady state, and at sludge ages of 8, 10, 15 and 20 days, an increase i n P release i n the anaerobic zone led to an increase i n o v e r a l l P removal. At a 20 day SRT they found the equation: [overall P uptake = 1.145(P released) + 3.14] f i t the data with an R squared factor of 0.992. The 3.14 was att r i b u t e d to metabolic requirements for t h e i r p a r t i c u l a r biomass. Comeau (1984) also looked at the e f f e c t of n i t r a t e addition on P uptake i n three batch t e s t s . Several hours a f t e r a l l acetate had been consumed by the biomasses under anaerobic conditions, he added n i t r a t e to each of the t e s t s . Phosphate was then taken up at a rate which appeared to increase with increased o r i g i n a l acetate addition. S i m i l a r l y , the d e n i t r i f i c a t i o n rate appeared to increase with increased o r i g i n a l acetate addition. Coincident to the disappearance of n i t r a t e , phosphate was again released at rates s i m i l a r to those i n the slow release period p r i o r to n i t r a t e addition. In the batch tests run by Gerber et al.(1986) acetate and propionate seemed to r e s u l t i n some of the highest d e n i t r i f i c a t i o n and ammonia oxidation rates under anoxic and aerobic conditions respectively. These rates were much lower when butyrate and other short chain f a t t y acids were used as substrate. Gerber et a l . observed the fast-slow phosphate release i n the presence and absence of substrate, respectively, l i k e Rabinowitz. They also showed a fast-slow phosphate uptake i n the subsequent aerobic zone i n the presence and absence of ammonia, respectively. The disappearance of ammonia was concurrent with the production of n i t r a t e , so i t can not be i n f e r r e d from t h i s data which parameter, i f either, was related to the change i n phosphate uptake rate under aerated conditions. Under anoxic conditions, they observed the following when adding acetate: 1. a rapid phosphate release i n the presence of acetate and n i t r a t e ; 2. a slow uptake of phosphate i n the absence of acetate but presence of n i t r a t e ; 3. a slow release of phosphate i n the absence of acetate and n i t r a t e . Figure 2.11 i l l u s t r a t e s t h i s pattern. This l a s t slow release i s an example of secondary release which could take place i n an oversized anoxic zone. Rensink et a l . (1981) operated ten complete-mix reactors i n s e r i e s — t h e f i r s t f i v e mixed only and the l a s t f i v e aerated, l i k e an A/0 process. The course of P, COD, NH3 and N03 at four d i f f e r e n t COD loading rates, using a medium strength, s e t t l e d domestic sewage was i l l u s t r a t e d . At sludge loading rates of 12 0 and 230 g COD/kg sludge/day (which corresponded to a 30 day SRT, 15 hour actual HRT and a 17 day SRT, 7.5 hour actual HRT, r e s p e c t i v e l y ) , they found : 1. Most of the COD was taken up i n the f i r s t anaerobic reactor (some uptake did take place i n the f i r s t aerobic reactor); 2. NH4 was completely u t i l i z e d i n the f i r s t two aerobic reactors; 3. n i t r i f i c a t i o n was generally complete a f t e r the f i r s t two or three aerobic reactors; 4. rapid P release i n the f i r s t three anaerobic reactors followed by a slower P release i n the other two reactors at the lower sludge loading. The rapid P release lasted through a l l f i v e anaerobic reactors at the higher COD loading rate. Gerber and Winter (1984) studied the e f f e c t of extended anaerobic retention time on phosphate removal using four three- stage Phoredox processes i n p a r a l l e l , each consisting of complete-mix basins i n s e r i e s . Actual anaerobic HRT's varied from 4 to 16 hours, with unaerated volume fr a c t i o n s ranging between 60 and 78% respectively. The authors found P release rates i n the anaerobic zone ranging from 3.5 mg/g MLSS/h i n i t i a l l y , dropping to 0.5 mg/g MLSS/h p r i o r to discharge. S i m i l a r l y , P uptake rates i n the aerobic zone ranged from 4.0 mg/g MLSS/h i n i t i a l l y , dropping to 0.6 mg/g MLSS/h p r i o r to discharge. The same was true for anoxic zone P uptake except that the maximum rate was only h a l f the value under aerobic conditions. This contrasts with the findings of Comeau et a l . (1987) who found the P uptake rates i n the presence of oxygen and nitrogen to be the same. One possible explanation i s that some simultaneous P release was taking place, thus reducing the net P uptake rate. Another p o s s i b i l i t y i s that the f r a c t i o n of bio-P d e n i t r i f y i n g organisms was less i n the Gerber and Winter study. S t i l l another p o s s i b i l i t y i s that the concentration of n i t r a t e s was l i m i t i n g the P uptake rate i n the Gerber and Winter study. Ammonia u t i l i z a t i o n and n i t r i f i c a t i o n rates i n the aerobic zone varied from 1.7 mg/g MLSS/h i n i t i a l l y , tapering o f f to zero p r i o r to discharge. D e n i t r i f i c a t i o n rates i n the anoxic zone varied from a high of 1.4 mg/g MLSS/h i n the f i r s t basin to 0.5 mg/g MLSS/h i n the subsequent basin. The researchers also concluded that there were no detrimental e f f e c t s due to extended anaerobic retention times on COD or P removal, on n i t r i f i c a t i o n and d e n i t r i f i c a t i o n or on SVI, sludge bulking or foaming. Fukase et a l . (1985) operated a 3 stage anaerobic-4 stage aerobic A/O type process using municipal wastewater. They found that P removal decreased with increasing actual aerobic HRT from 2.3 - 5 hours. I t should be noted however that SRT was also simultaneously varied from 4.3 - 8.0 days respectively. P/ BOD values were i n the 0.04 to 0.05 mg/mg range. Jones et a l (1987) used 2 unaerated and 4 aerated complete- mix reactors i n series, with each reactor having a 0.9 hour actual HRT, to study the e f f e c t of substrate addition on the bio-P process. The feed was a weak to medium strength municipal sewage. Their r e s u l t s were s i m i l a r to those previously reported by Rabinowitz (1985) (ie . i n i t i a l rapid P release or uptake followed by slower release or uptake i n the anaerobic or aerobic zones, r e s p e c t i v e l y ) . They found that n i t r i f i c a t i o n was e s s e n t i a l l y complete a f t e r 0.9 hours actual aerobic HRT as was TKN u t i l i z a t i o n . E s s e n t i a l l y a l l of the COD removal took place i n the f i r s t anaerobic zone, even with acetate additions of 34 mg/L as COD (measured i n the reactor). Daigger et a l . (1987) operated a p i l o t scale high rate ( i e . low HRT t o t a l nominal 4 - 7 hours, low SRT t o t a l 5-10 days) multistage UCT type process, using a weak, septic domestic sewage. No chemical addition or primary sludge fermentation was 26 included. As i n the previous works reviewed, the authors also found the same phosphate release pattern i n the anaerobic zone. The i n i t i a l rapid release phase was t y p i c a l l y over a f t e r l e s s than 10 minutes actual HRT. The slow release continued s t e a d i l y i n the remaining 2 anaerobic c e l l s ( i e . 20-30 minutes actual HRT). Four t y p i c a l anaerobic phosphate release patterns were presented which were representative of good removal ( i e . e f f l u e n t P<1 mg/L) and four which were representative of poor removal ( i e . e f f l u e n t P>1 mg/L). The researchers found l i t t l e d i s t i n c t i o n between the two groups. By organizing these patterns into groups on the basis of phosphate removal divided by BOD or COD removal( P/ BOD or P/ COD) i t appears that when phosphate release was high during the rapid release phase, the P/ BOD or P/ COD was also r e l a t i v e l y high (0.04 or 0.02 mg/mg res p e c t i v e l y ) . When phosphate release was low during the rapid release phase, the P/ BOD or P/ COD r a t i o s were also r e l a t i v e l y low. PHA was not measured, but high phosphate release (during the rapid phase) could be an i n d i c a t i o n that a s i g n i f i c a n t amount of carbon storage took place with subsequent high phosphate removal. One very i n t e r e s t i n g observation made was that the s p e c i f i c phosphate uptake rate ( i e . mg P/g MLSS/h) i n the aerobic zone was generally higher during periods of low e f f l u e n t phosphate ( i e . P<1 mg/L) for the same soluble phosphate concentration i n the primary e f f l u e n t . The explanation presented was that some l i m i t i n g factor (such as carbon storage) was hindering the phosphate uptake rate during the periods of poor phosphate removal. In other words, the aerobic phosphate uptake rate would be higher i f the quantity of stored carbon i n the organisms was higher. Phosphate release i n the anaerobic zone increased with increases i n the feed strength, as measured by BOD or COD, but there was no str a i g h t l i n e c o r r e l a t i o n between phosphate release and BOD or COD. I t i s possible that these two parameters measure more than j u s t the type of organic material which stimulates phosphate release. Anaerobic phosphate release was also reported by Daigger et a l . 1987 to be affected by NOx recycled from the anoxic zone back to the anaerobic zone, with reduced phosphate release during periods of s i g n i f i c a n t NOx recycle. Furthermore, t h i s appeared to lead to poorer phosphate removal. One other relevant finding reported was that actual anaerobic HRT's ranging from 0.4 - 1.2 hours did not have any s i g n i f i c a n t e f f e c t on phosphorus removal. The authors speculated that the septic nature of the sewage gave r i s e to f a s t P release. This apparently contradicts Barnard's speculation that the slow phosphate release, termed secondary release, was 28 detrimental to good phosphorus removal. I t should be noted, however, that other factors such as anoxic and aerobic HRT, SRT, temperature, DO, feed strength, etc. a l l varied when anaerobic HRT was varied so that enhancement or hinderance of the phosphorus removal process may have been masked by other factors. Aerobic zone HRT was also believed to be a factor i n phosphate removal. When the HRT was increased, phosphate removal dropped o f f . This was again explained by the idea that more oxidation of stored organic matter had taken place and that subsequently the phosphate uptake rate was reduced. Decreased observed sludge y i e l d was also noted concurrent to the increase i n aerobic HRT, supporting the idea of increased oxidation. At a s l i g h t l y underloaded Phoredox plant, Stevens and Oldham (1987) suspected over-aeration as the cause of re-release of phosphorus i n the reaeration zone. A reduction i n DO l e v e l s from 2 mg/L to 1 mg/L improved the s i t u a t i o n , thus supporting the theory that the stores of carbon were being depleted. Comeau et a l . (1987) also reported that over-aeration was a factor i n reduced o v e r a l l phosphorus removal. S i m i l a r l y they speculated that over-aeration would lead to reduced carbon reserves (PHA), thus forcing bio-P bacteria to produce energy v i a poly-phosphate degradation. This would r e s u l t i n aerobic P release or a reduced o v e r a l l P uptake rate. 29 2 . 1 . 1 Summary In summary, although there i s s t i l l no o v e r a l l consensus as to the exact biochemical mechanisms which take place i n the b i o l o g i c a l phosphorus removal process, there appears to be some general agreement i n a few areas. 1. Short-chain f a t t y acids (SCFA) or v o l a t i l e f a t t y acids (VFAs) e i t h e r i n i t i a l l y present i n the feed or generated i n a fermenter or produced during anaerobiosis are stored i n t e r n a l l y by bio-P type organisms. These acids are stored i n the form of long chain carbon reserves such as poly - /3-hydroxybutyrate (PHB) and poly-/3-hydroxyvalerate (PHV) , together referred to as poly- /?-hydroxyalkanoate (PHA) . 2 . The energy to carry out t h i s storage comes from the cleavage of poly-phosphate reserves within the bio-P type organisms. 3. Bio-P type organisms are thus defined as those organisms able to store both carbon and phosphorus. As a r e s u l t of t h i s a b i l i t y they have an advantage over other non-bio-P type organisms; hence t h e i r p r o l i f e r a t i o n i n bio-P type processes. 4. Subsequently, under metabolizing conditions ( i e . i n the presence of electron acceptors such as N03 and 0 2), these bio-P type organisms then take up phosphate from solu t i o n and store i t as poly-P. 5 . The energy for phosphate uptake comes from the consumption of the stored PHA. 6. Bio-P type organisms degrade t h e i r poly-P reserves or oxidize t h e i r i n t e r n a l PHA reserves to generate maintenance energy. 7. Nitrate or oxygen recycled to the anaerobic zone has a detrimental e f f e c t on phosphate removal. 8. Over oxidation could take place i n the aerobic zone, leading to reduced P removal c a p a b i l i t i e s . 2.2 Hypotheses On the basis of the l i t e r a t u r e reviewed, two hypotheses applicable to the treatment of t y p i c a l Canadian wastewaters were proposed to be tested: 1. Extended detention time i n the anaerobic and anoxic zones lead to a s i g n i f i c a n t amount of "secondary" P release; 2. Extended detention time i n the aerobic zone leads to excess oxidation, which i s detrimental to the o v e r a l l phosphorus removal process. Test conditions as follows were used as a s t a r t i n g point to evaluate the hypotheses: 1. A weak domestic sewage containing about 4-5 mg P/L, about 250 mg COD/L, and about 20-30 mg TKN/L; 2. A simple carbon substrate addition of 30 mg COD/L (measured i n the feed ) which would be s u f f i c i e n t to enhance P removal, from the 1-2 mg/L range of metabolic requirements to 3-4 mg/L t o t a l ; 3. A UCT type process without the in t e r n a l recycle (for increasing nitrogen removal) and other recycle r a t i o s of 1:1 based on in f l u e n t flows; 4. Actual anaerobic, anoxic and aerobic HRT's of 1.25 hours, 1.5 hours and 4.0 hours respectively as i n Manoharan 1989. 2.3 Objectives The objective of t h i s research was to optimize the bio-P process as applied to a weak sewage, with respect to HRT i n each of the process zones. This goal was to be achieved by changing the HRT of the various zones with a l l other operating c h a r a c t e r i s t i c s being held constant. S p e c i f i c a l l y , the program was c a r r i e d out as follows: 1. Anaerobic Zone - Study the e f f e c t s of an anaerobic HRT reduction on the anaerobic P release, e f f l u e n t P and P removal c h a r a c t e r i s t i c s . - Investigate the use of PHA tests to indicate when "secondary P release" i s taking place i n the anaerobic zone of the UCT process with acetate and propionate additions t y p i c a l of the quantity produced i n a primary sludge fermenter. 2. Aerobic Zone - Observe the pattern of P uptake i n the aerobic zone to determine i f a reduction i n aerobic HRT has any p o t e n t i a l to improve e f f l u e n t P or P removal. 3. Anoxic Zone - To study the e f f e c t s of an anoxic HRT reduction on the anoxic P release and P uptake, e f f l u e n t P and P removal c h a r a c t e r i s t i c s . 33 Chapter 3. Experimental Procedures A b r i e f description of the process, the sampling and a n a l y t i c a l methods, the feed source and composition, and the biomass i s presented here so that the reader might better understand the r e s u l t s and discussion which follow. I t may also indicate the inherent l i m i t a t i o n s of the study due to design, operational or feed c h a r a c t e r i s t i c s . The s i z i n g of the process and s p e c i f i c a t i o n of feed c h a r a c t e r i s t i c s were a l l based on Manoharan's (1988) work so that the r e s u l t s of the two studies would be d i r e c t l y comparable. 3.1. Process Description 3.1.1. Physical Apparatus Ch a r a c t e r i s t i c s Two UCT process t r a i n s were operated i n p a r a l l e l . Both modules were i d e n t i c a l i n a l l respects. The schematic representation of one module i s shown i n Figure 3.1. Figure 3.2 shows one module i n p r o f i l e view which i l l u s t r a t e s how the anaerobic HRT was adjusted. The reactors, c l a r i f i e r s , and i n f l u e n t and e f f l u e n t tanks were constructed of various diameter p l e x i g l a s s cylinders with p l e x i g l a s s bases. A long c y l i n d r i c a l shape, giving a depth to diameter r a t i o of about 3:1 was used to minimize a i r entrainment into the anaerobic and anoxic reactors. This shape was also 34 ANAEROBIC ANOXIC REACTOR REACTOR AEROBIC REACTORS MIXED LIQUOR RECYCLE Figure 3.1 Experimental UCT Process CHEMICAL ANAEROBIC ANOXIC SUBSTRATE REACTOR REACTOR INFLUENT AEROBIC REACTORS CLARIFIER EFFLUENT Figure 3.2 Experimental Process Schemat ic in Profile 35 desirable for the aerobic reactors to allow for good mixing without excessive a i r flows. The feed tank was also r e l a t i v e l y deep to minimize a i r entrainment. The c l a r i f i e r s had conical shaped bottoms. A small diameter cylinder i n the centre served to d i s s i p a t e the turbulence caused by discharge from the f i n a l aerobic reactor. Table 3.1 l i s t s the dimensions and capacities of a l l vessels. I n i t i a l l y only the feed tank and anaerobic and anoxic reactors were mechanically mixed. Later, i n order to control D.O. to 2 mg/L or less, the f i n a l two aerobic c e l l s of the control module and f i n a l three aerobic c e l l s of the experimental module were also mechanically mixed. A mechanical scraper was used i n the c l a r i f i e r s to promote s e t t l i n g and underflow discharge. The suspended s o l i d s i n the anaerobic and anoxic reactors were kept suspended with mechanical mixers having s l i g h t l y twisted rectangular blades to give some a x i a l component to the v e l o c i t y . Variable speed motors were operated between 50 and 75 rpm. The paddle shafts were constrained at the centre of each reactor base, with the bottom of each paddle being about 3 cm above the bottom of the reactor. There was about a 0.5 cm clearance between the paddle t i p and the reactor wall. Since a considerable amount of mixing energy was used, f l o a t i n g covers made of styrofoam were i n s t a l l e d to reduce a i r entrainment due to vortexing. Table 3.1 Equipment S p e c i f i c a t i o n s 36 Vessel Dimensions (cm) Liquid Volume (diam. x height) (L) Influent feed tank 36 x 30 up to 30 Chemical feed c y l i n d e r 5 x 51 1 Anaerobic reactor 7.6 x 29 1.3 3 Anoxic reactor 9 x 35 2.2 5 Aerobic reactors (each) 7.0 x 26 1 C l a r i f i e r 8.3 x 19 1 E f f l u e n t tank 15 x 79 up to 14 Table 3.2 Operational C h a r a c t e r i s t i c s Feed Rate Sewage only 0.47 L/h Chemical only 0.03 L/h Combined feed 0.50 L/h Recycle Ratios C l a r i f i e r underflow recycle : Combined feed 1 : 1 Anoxic to anaerobic recycle : Combined feed 1 : 1 I n i t i a l Actual Hydraulic Retention Times Anaerobic 1.33 h Anoxic 1.5 h Aerobic 4.0 h C l a r i f i e r 1.0 h Solids Retention Time (Total Process) 20 days A slow speed, S-shaped paddle about 2 cm wide, with an e f f e c t i v e length of about 20 cm was used to maintain the feed s o l i d s i n suspension. The paddle was set about 1 cm above bottom. The shaft was constrained at the top of the feed tank. The mixer was set at 10 rpm. A f l o a t i n g cover of styrofoam was used i n addition to the l i d , to reduce a i r entrainment. Fixed speed mixers at 12 and 25 rpm were used to mix the l a s t three aerobic reactors. Paddles, operated i n a manner si m i l a r to c l a r i f i e r scrapers except at higher rpm's, were used as mixing devices. This scraping along the circumference of the base of the reactors prevented s e t t l i n g . The bulk of the mixing was s t i l l by a i r . Feed from the i n f l u e n t tank was pumped into the anaerobic reactors. The sodium acetate - sodium propionate mixture was separately pumped from 1.0 L graduated cylinders (one for each module) into the anaerobic reactors. From the anaerobic reactors, mixed l i q u o r flowed by gravity to the subsequent anoxic and aerobic reactors and on to the c l a r i f i e r s . Recycles were pumped from the anoxic reactors to the anaerobic reactors and from the c l a r i f i e r underflows to the anoxic reactors. Reactor i n l e t s and discharges were staggered and spaced to minimize short c i r c u i t i n g . The raw sewage, acetate/propionate mix and the anoxic zone mixed l i q u o r recycle (a-recycle, Figure 3.1) entered the anaerobic reactor 1 cm above the bottom at 12 38 o'clock, 3 o'clock and 6 o'clock positions. This was a zone of maximum turbulence to provide a uniform mix of the three streams. Discharge to the anoxic reactor was from a point about 5 cm below the l i q u i d l e v e l into the anaerobic reactors. The c l a r i f i e r underflow recycle (s-recycle, Figure 3.1) entered the anoxic reactors at a point 1 cm above the bottom, i n the high turbulence zone. The i n l e t from the anaerobic reactors was about 5 cm below the anoxic reactor's l i q u i d l e v e l . The discharge to the f i r s t aerobic c e l l was from a point about 10 cm above the bottom of the anoxic reactor. S i m i l a r l y the anoxic mixed l i q u o r recycle (a-recycle) was taken from the opposite side at about the same l e v e l . The i n l e t and discharge points i n the four aerobic reactors of each module were staggered at l e v e l s 5 cm above the bottom and 5 cm below the l i q u i d l e v e l . The f i n a l aerobic reactor discharged to a point about h a l f way up the c l a r i f i e r from a point j u s t above the middle of the aerobic reactor as seen i n Figure 3.2. In t o t a l , four Masterflex pump heads were used per module to pump the sewage, the acetate/propionate mixture, the a- recycle and the s-recycle. A l l pump heads fo r each module were driven by a single Daton variable speed 1/8 horse power motor. In t h i s way, the r a t i o of the chemical substrate addition rate and a and s-recycle r a t i o s to the in f l u e n t sewage rate were a l l f i x e d regardless of pump speed v a r i a t i o n s . Since the arrangement of pump heads and tubing were the same, both modules could be adjusted to the same flow conditions simply by adjusting the rpm of the two motors. The resultant flow rates, HRT's, and recycle r a t i o s are c i t e d i n Table 3.1. The 50 rpm vari a b l e speed motors were adjusted to about 10 rpm to achieve the desired flow rates. The c o n t r o l l e r s could be f i n e l y adjusted, allowing for v i r t u a l l y i d e n t i c a l hydraulic conditions i n both modules. Figure 3.3 i s a schematic of the a i r , system. Laboratory a i r at an average pressure of 60 psig was reduced i n two stages to about 20 and 8 psig, respectively. A simple Tee-joint s p l i t the a i r to eithe r module. A manifold system further s p l i t the a i r flow to the four aerobic reactors of each module. Needle valves between the Tee-joint and manifolds allowed f o r some coarse regulation of the a i r supply to each module. Needle valves were also placed on each l i n e to the i n d i v i d u a l reactors to provide the fin e a i r control. Even though the main l i n e was 3/8" ID and the in d i v i d u a l l i n e s were 1/8" ID, adjustment of a i r flow to one reactor would a f f e c t the a i r flow to other reactors. Furthermore, v a r i a b i l i t y i n l i n e pressure resulted i n fl u c t u a t i n g a i r flow rates and hence temporal v a r i a t i o n i n DO throughout a l l aerobic reactors. This system for a i r flow regulation allowed for only crude control of DO (±0.5-1.0 mg/L). . BUILDING AIR » 60 PSIG WATER K N O C K - O U T B O T T L E 3.1.2 Operational Characteristics Daily wasting of 1/20 of the t o t a l process volume of mixed l i q u o r suspended s o l i d s (MLSS) from the f i n a l aerobic reactor was used to maintain the t o t a l s o l i d s retention time (SRT) at about 20 days. The wasting rate was based on approximations of the mass of MLSS i n a l l reactors (not including the c l a r i f i e r ) and allowing for average s o l i d s loss i n the ef f l u e n t . The i n l e t and outlet l i n e s were is o l a t e d from the c l a r i f i e r and other reactors during wasting. The l a s t aerobic reactor was chosen for wasting because the stored poly-P l e v e l s were highest at t h i s point. T y p i c a l l y , about 330 mL of MLSS was drained o f f d a i l y . On sampling days, due to the quantities of MLSS required for the various t e s t s , l i t t l e or no additional wasting was necessary. Note that on these days, while the mass of MLSS removed was consistent with the norm, the wasting lo c a t i o n was d i f f e r e n t . I n i t i a l l y , the DO was controlled to keep s o l i d s i n suspension, which resulted i n high DO l e v e l s . In an attempt to prevent excessive DO l e v e l s i n the f i n a l two aerobic reactors, the DO was kept below 1.0 mg/L i n the f i r s t two aerobic reactors. S t i l l the DO was above 3.0 mg/L i n the f i n a l two aerobic reactors. Some s e t t l i n g was s t i l l apparent i n a l l aerobic reactors. Mechanical mixers were then added to the l a s t two aerobic reactors to allow for DO control below 3.0 mg/L while preventing s e t t l i n g . The a i r rate, and hence the DO i n the f i r s t two aerobic reactors was increased to prevent s e t t l i n g . Later i t seemed that the P uptake rate was adversely affected by low DO. In an attempt to prevent DO or aeration rate from l i m i t i n g the P uptake rate, the DO was increased i n the f i r s t two aerobic reactors to about 2.0 mg/L. An objective of 2.0 ± 0.5 mg/L was decided on for a l l aerobic reactors so that DO d e f i c i e n c i e s (or excesses) would be the same for a l l reactors. A f i n a l refinement to prevent DO from entering the anoxic zone v i a the c l a r i f i e r underflow (s-recycle) was to reduce the DO target l e v e l to less than 1.0 mg/L i n the f i n a l aerobic reactor. 3.1.3. Batch Tests Two sets of batch tests were run to study how P04, NOx, PHA, TOC, NH3 and VFA varied with time i n an anoxic zone. To simulate anoxic conditions, MLSS from the anaerobic zone and the c l a r i f i e r underflow were mixed i n the same mass and volumetric proportions that normally enter the anoxic zone of the flow- through process t r a i n . The r a t i o of volumetric flow from the anaerobic reactor into the anoxic reactor, to the c l a r i f i e r underflow into the anoxic reactor, was 2 to 1. On a mass basis, the r a t i o was 1 to 2. The batch t e s t i n g apparatus i s shown i n Figure 3.4. 3.2 Sampling and A n a l y t i c a l Methods 3.2.1. Flow-Through Process A sampling schedule for the flow-through process t r a i n was followed as shown i n Table 3.3. On occasion, the normal sampling date was postponed due to the presence of non- representative conditions, which occurred during equipment f a i l u r e s . Furthermore, as time progressed, some modifications were also made to t e s t for more parameters or to improve technique. Due to the large number of samples, a great deal of economy had to be applied to the sampling procedure. Moreover, with 6 reactors, a t o t a l volume of about 7.6 l i t r e s , an SRT of 20 days, e f f l u e n t TSS of about 10 mg/L'and a feed rate of 12 L/day, only s l i g h t l y more than 300 mL of mixed-liquor was av a i l a b l e per side for analysis. Therefore the sampling was c a r r i e d out as follows: 1. 20-25 mL was extracted from each reactor and f i l t e r e d through standard glass f i b r e f i l t e r s (Whatman 934AH). The Table 3.3 Weekly Sampling Schedule 44 Analysis Raw Influent Bio- reactors C l a r i f i e r E f f l u e n t B0D5 1-2/week 1/week 2/week COD d a i l y 1/week occasionally TOC 2/week 1-2/week occasionally VFA 2/week 2/week 2/week TSS 1-2/week 2/week 2/week VSS 1-2/week 1/week 1/week NH3 1/week 1/week 0 NO 3 1-2/week 2/week 0 NO 2 1-2/week 2/week 0 TKN d a i l y 0 occasionally TOTAL-P d a i l y 0 occasionally ORTHO-P 2/week 2/week occasionally PH 1/month 1/month 1/month DO 1/week d a i l y 0 PHA 0 1/week 0 %P 0 1/week 0 n o n f i l t r a b l e residue remaining on the f i l t e r s was dried at 104°C for at l e a s t one hour and weighed to determine the Total Suspended Solids (TSS) value. These same caked f i l t e r s were l a t e r f i r e d at 550°C for one hour to determine the V o l a t i l e Suspended Solids (VSS) value. The supernatant was c o l l e c t e d and preserved with 1-2 drops of phenolmercuric acetone and stored at 4°C. This supernatant was used for Ortho-Phosphate (P04-P) measurements, analyzed using the ascorbic acid reduction method (Technicon Autoanalyzer II, Method No. 94-70W, 1973). Nitrate plus Ni t r i t e - N i t r o g e n (NOx-N) measurements were made simultaneously using the Technicon Autoanalyzer Method no. 100-70W (1973) with a cadmium wire modification suggested by W i l l i s (1980). Once per week, Ammonia-Nitrogen (NH3-N) was also measured on the Technicon Autoanalyzer I I , using method No. 350.1 (1974). A portion of the supernatant from the TSS/VSS samples was frozen p r i o r to adding the preservative for use i n measuring Total Carbon (TC) and Inorganic Carbon (IC) using a Beckman Model 915A Total Carbon Analyzer with a Model 865 Infared Analyzer. The TC furnace temperature was 950°C and the IC oven temperature was 150°C. On the days when COD was to be determined, the sample volume was increased to 50 ml to give an extra 20 mL for the f i l t e r e d COD t e s t as outlined i n Standard Methods (13th Ed. A.P.H.A., 1970) 2. Samples for V o l a t i l e Fatty Acids (VFA) determination were taken separately to avoid v o l a t i l i z a t i o n . They were f i l t e r e d through pre-washed Whatman 4 or equivalent f i l t e r paper and then frozen. VFA's were then determined by gas chromatography as described i n the Supelco B u l l e t i n 751 E (1982). The Hewlett-Packard Model HP5880, a computer controlled gas chromatograph equipped with a flame i o n i z a t i o n detector (FID) was used for the analysis with nitrogen as the c a r r i e r gas. A glass column packed with 0.3% Carbowax / 0.1% H3P04 on 60/80 Carbopak C (Supelco, Inc.) was used. One / i L of a c i d i f i e d (1% phosphoric acid) sample was subjected to gas chromatographic analysis using external standards dissolved i n 0.1% aqueous phosphoric acid for q u a n t i f i c a t i o n . 3. Poly -0-hydroxybutyrate (PHB) and Poly - 0-hydroxyvalerate (PHV) samples were c o l l e c t e d separately i n a 25 mL aliquot which was divided into two t e s t tubes. Following centrifugation at 1800 g fo r 5 min. and decanting the supernatant, the remaining sludge p e l l e t was frozen for storage. The frozen p e l l e t was l y o p h i l i z e d to remove a l l water, leaving a f l u f f y mass ready for the extraction process. The extraction process involved weighing of the s o l i d , adding chloroform and a c i d i f i e d methanol, heating at 100°C for 3 1/2 hours, cooling, water washing, shaking, extracting the organic layer, washing the organic layer, shaking and f i n a l l y extracting the organic layer. The remaining organic f r a c t i o n was subjected to gas chromatographic analysis on the same machine used for VFA analysis. 1 /xL of extracted sample was injected through the 1.83 m long by 2 mm i n t e r n a l diameter s i l i n i z e d glass column packed with Chromosorb W AW DMCS 80-100 mesh coated with 5% Carbowax M20 TPA. The experimental chromatograph conditions were as follows: i n j e c t i o n port temperature of 150°C, detector temperature of 200°C. The oven temperature program was: i n i t i a l temperature of 100°C, i n i t i a l time of 1 minute, temperature increase rate of. 8°C/minute, f i n a l temperature of 150°C, f i n a l time of 0.25 minutes, post run temperature of 180°C, post run time of 4 minutes, and an equilibrium time of 3 minutes. The gas flow rates were as follows: N2 ( c a r r i e r gas) 20 mL/minute, He 30 mL/minute and a i r 400 mL/minute. (Comeau 1984). This same l y o p h i l i z e d p e l l e t was also used for Percent Phosphate (%P) determination. A weighed aliquot was f i r s t acid digested i n a block digester using sulphuric acid with a potassium sulphate c a t a l y s t . The sample was then analyzed on the Technicon Autoanalyzer II using Method No. 327-730 (1974). 4. The feed was sampled for COD, TP and TKN d a i l y . U n f i l t e r e d samples were a c i d i f i e d with concentrated H2S04 and placed i n the cold room for storage at 4°C. A 100 mL aliquot was 48 f i l t e r e d to determine TSS once or twice per week as described previously. The supernatant was used for soluble COD and TOC analysis. The sample used for TOC was frozen, not a c i d i f i e d , for preservation. Total Phosphate (TP) and Total Kjeldahl Nitrogen (TKN) were both measured on the Technicon Autoanalyzer II by Method No. 327-73 (1974). A single sample was f i r s t a cid digested i n a block digester using sulphuric acid and potassium sulphate. VFA's were sampled separately from the feed to avoid loss through v o l a t i l i z a t i o n . The procedure for VFA determination was the same as described previously. 5. Dissolved Oxygen (DO) was measured using a Yellow Springs Instrument Co. Model No. 54a DO meter and probe. The probes were c a l i b r a t e d i n i t i a l l y , using the modified Winkler Azide method and l a t e r by the a i r saturation method. Membranes were changed regularly. Problems zeroing the meter existed u n t i l a new probe was used. This did not seem to a f f e c t the DO reading i f the value was over 1 mg/L. At lower DO values, the e f f e c t was unknown. 3.2.2. Batch Test To commence a batch t e s t , approximately 440 mL of aerobic MLSS from the l a s t aerobic reactor were syphoned into a 500 mL Earlenmeyer f l a s k . The f l a s k was sealed with a stopper which had been f i t t e d with two drain l i n e s and one helium f i l l e d balloon as shown i n Figure 3.4. P r i o r to sealing, a s t i r bar was dropped inside and the a i r space was purged with helium gas. Aft e r 20 minutes of s e t t l i n g , 220 mL of the supernatant was pumped o f f . Helium from the balloon replaced the pumped-off l i q u i d volume so that the contents were s t i l l at atmospheric pressure. The f l a s k was placed on a mixing plate and completely mixed. About 35 mL of sample was drawn o f f by syringe. The anaerobic zone of the flow-through process t r a i n was sampled p r i o r to pumping 330 mL of anaerobic MLSS d i r e c t l y into the sealed, completely mixed Earlenmeyer f l a s k . A f t e r 30 seconds of mixing, 35 mL of MLSS was drawn o f f by syringe for a time zero sample. The sample schedule, sample volumes and analyses are l i s t e d i n Table 3.4. At each sampling time, 10 mL of MLSS was drawn o f f for TSS, VSS, P04, NOx, TOC and NH3 analyses. A separate 5 mL aliquot was used for VFA analysis. Another 20 mL was used for PHA analysis. The a n a l y t i c a l methods are described i n section 3.2.1. 3.3. Feed Source and Composition 3.3.1. Raw Sewage As mentioned e a r l i e r , i t was desired to duplicate the feed c h a r a c t e r i s t i c s used by Manoharan (1988) so that the r e s u l t s of the two studies would be d i r e c t l y comparable. Therefore the UBC p i l o t - p l a n t i n f l u e n t was selected as the sewage source. Table 3.5 l i s t s the major c h a r a c t e r i s t i c s of the sewage used by Table 3.4 Batch Test Sampling Schedule Time Volume Analyses (min) (mL) P04 PHA NOx VFA TOC NH3 TSS a -10 35 * * * * * * b -5 3 5 * * * * * * * C 0 3 5 * * * * * * * 5 3 5 * * * * * * * 10 30 * * * * * * 15 3 0 * * * * * * 20 30 * * * * * * 30 3 0 * * * * * * 45 30 * * * * * * 60 30 * * * * * * 75 3 0 * * * * * * 90 30 * * * * * * d 120 3 0 * * * * * * a. Se t t l e d aerobic sample b. Anaerobic sample c. Within 3 0 seconds of mixing anaerobic and c l a r i f i e r underflow MLSS d. Batch t e s t #1 only Table 3.5 Target Feed C h a r a c t e r i s t i c s 51 Component Target Manoharan I n i t i a l P i l o t - Plant F e e d COD (mg/L) 200-260 203-256 160 TOTAL-P (mg/L) 4-5 3.8-4.6 2-3 TKN (mg/L) 20-30 22-30 18 Table 3.6 Richmond Feed C h a r a c t e r i s t i c s Date of C o l l e c t i o n / Sampling Raw Total COD (mg/L) Raw Total BOD5 (mg/L) Diluted Total COD of Sewage Only (mg/L) Aug. 1987 Sept. 1987 Oct. 1987 Nov. 1987 Dec. 1987 21 26 4 17 22 30 7 14 21 28 4 10 16 25 4 10 451 459 546 495 504 660 478 497 467 375 305 268 568 510 434 420 210 150 156 124 296 218 227 224 171 156 120 270 215 228 184 192 179 173 210 195 206 255 217 217 217 228 204 197 231 209 248 - 424 - 237 - 254 - 220 - 410 - 385 - 275 - 256 - 239 - 284 - 250 - 236 - 276 - 280 - 265 - 273 Manoharan and the target concentrations for t h i s experiment. At the time t h i s research was begun, however, the feed strength (as COD) was much lower than the target strength as shown i n Table 3.5. A f t e r several attempts to c o l l e c t stronger sewage had f a i l e d , i t was decided to use sewage from the Lulu Island sewage treatment plant i n Richmond, B.C. The range and average concentrations of the raw and d i l u t e d batches of Richmond sewage are l i s t e d i n Table 3 . 6 . The sewage was d i l u t e d with tap water to the target COD strength. Sodium triphosphate was added to adjust the phosphate . concentration to target l e v e l s . V a r i a b i l i t y i n feed strength from batch to batch and from sample to sample made control of the feed strength within the target range very d i f f i c u l t . I n i t i a l l y one or two of the 20 or so carboys c o l l e c t e d per batch were tested f o r COD, TP and TKN. These r e s u l t s were used to determine the d i l u t i o n rate for the remaining carboys. While t h i s method proved s a t i s f a c t o r y for Manoharan, i n t h i s study, feed strength v a r i a t i o n from carboy to carboy was unacceptable. In order to improve on the d i l u t i o n process, about eight carboys were poured into a 200 L tank. The contents were mixed and sampled. Subsequent d a i l y withdrawals were d i l u t e d based on the i n i t i a l concentration. While the contents of the tank were mixed p r i o r to sampling and withdrawing, the tank was l e f t unmixed overnight. Feed strength v a r i a b i l i t y continued to p e r s i s t possibly due to poor mixing. Therefore the tank was only f i l l e d h a l f f u l l to improve the mixing. This reduced the feed strength v a r i a b i l i t y from ±100% to ±50%. Since the Richmond feed was considerably stronger than the target strength, one batch of sewage would l a s t over 40 days. In order to prevent excessive b i o l o g i c a l change to the sewage while i n storage a fresh batch of feed was c o l l e c t e d every three weeks. V a r i a b i l i t y i n feed strength ceased to be a major problem but suspected metals such as chromium i n the feed prompted a return to p i l o t - p l a n t sewage which had, i n the mean time, increased i n strength. Table 3.7 l i s t s the i n i t i a l , f i n a l and average concentrations of t h i s p i l o t - p l a n t feed. "3.3.2. Acetate/Propionate Chemicals Sodium s a l t s of acetic and propionic acids were added as 50:50 mixtures on a COD concentration basis. At the 9-10 rpm pump speed set to give flow and recycle rates of about 0.5 L/hour i n s i z e 13 tubing, size* 16 tubing was selected to feed the VFA s o l u t i o n at about 30-35 mL/h. The chemicals were mixed in concentrations to give a mass flow rate of 15 mg COD/hour or an equivalent concentration i n the feed of 30 mg COD/L. 54 Table 3.7 P i l o t - P l a n t Feed Ch a r a c t e r i s t i c s Date of Co l l e c t i o n Total B0D5 Total COD (mg/L) (mg/L) 200 - 266 183 - 229 187 - 245 160 - 224 163 - 239 210 - 224 189 - 210 Dec. 1987 Jan. 1988 Feb. 1988 Mar. 1988 16 28 20 20 15 7 16 101 45-77 60 47-83 45-90 52-89 37-45 3.3.3. C o l l e c t i o n and Storage of Sewage Raw sewage was f i l t e r e d through a 0.25 mm sieve and co l l e c t e d i n 20-25 L carboys, sealed t i g h t l y and stored within one hour i n a cold room at an average temperature of 6°C. The f i l t e r i n g was necessary to prevent l i n e plugging i n the lab scale project. The resultant sewage was then representative of primary e f f l u e n t with t y p i c a l TSS values of 100 mg/L. 3.3.4. Mixed Liquor and Start-up Mixed l i q u o r from the UBC p i l o t - p l a n t was used as seed for the laboratory-scale process t r a i n . About 20 L of MLSS was taken from the aerobic zone of the p i l o t - p l a n t and stored i n the cold room for several hours u n t i l needed. The experimental module was f i l l e d and started i n the afternoon of June 25th, 1987. The control side was f i l l e d and started the next morning. About 7.6 L of MLSS was d i s t r i b u t e d between the anaerobic, anoxic and aerobic reactors. The c l a r i f i e r was f i l l e d with tap water. The feed tank was f i l l e d with fresh sewage. One l i t r e of acetate - propionate mix was put into the chemical feed cyli n d e r . A i r was turned on to the aerobic reactors and adjusted to keep s o l i d s i n suspension without regard for DO l e v e l . The anaerobic and anoxic mixtures were turned on and the f l o a t i n g covers put i n place. The feed pump was turned on and the process allowed to run for about one hour. A f t e r e f f l u e n t had been flowing over the c l a r i f i e r discharge tube, the l e v e l of the c l a r i f i e r and the anaerobic and aerobic reactors was adjusted so that each reactor held the desired volume. A s i m i l a r start-up procedure was followed f o r the control module. Once both modules were running, a process of c a l i b r a t i n g flow rates and a i r rates was undertaken. The control module chemical feed pump could not be s a t i s f a c t o r i l y c o n t r o l l e d so a masterflex pump was substituted a f t e r about 10 days. Chemical feed rate was then adequately c o n t r o l l e d i n both modules. 57 Chapter 4. Results 4.1 General The r e s u l t s i n t h i s section are presented i n a chronological fashion without in-depth explanations or c o r r e l a t i o n s of parameters; these w i l l appear i n the section on Discussion. The research project could l o g i c a l l y be divided into two main periods. Period 1 was from start-up on June 26, 1987 to the time of the anaerobic HRT change on November 3, 1987 - a t o t a l of 130 days. Period 2 was from November 3, 1987 to the conclusion of experimentation on March 28, 1988 - a t o t a l of 146 days. A comparison of Period 1 to Period 2 should show the e f f e c t s of the anaerobic HRT change. Each of the two periods could be further broken down according to the type of sewage used. In each of the periods both Richmond and p i l o t - p l a n t sewage was used for a portion of the time. The time when Richmond sewage was used w i l l be indicated with an R. S i m i l a r l y , a PP w i l l indicate the use of P i l o t - p l a n t sewage. The period number w i l l follow the l e t t e r code so that a l l four parts would be designated as i n Table 4.1. A comparison of the two sewage types within the same period should show the e f f e c t s of sewage type and composition on P removal. 58 Table 4.1 Experimental Periods Time In t e r v a l Type of Sewage Used Period June 26-July 20, 1987 P i l o t - P l a n t PP1 Jul y 21-Nov. 3, 1987 Richmond Rl Nov. 4-Dec. 14, 1987 Richmond R2 Dec. 15-Mar. 28, 1988 P i l o t - P l a n t PP2 Table 4.2 Typi c a l Feed C h a r a c t e r i s t i c s Component PP1 Period Rl and R2 PP2 Manoharan BOD5 (mg/L) COD (mg/L) 160 TOC (mg/L) 30 VFA (mg/L) 0 Total-P (mg/L) 2-3 Ortho-P (mg/L) 2 TKN (mg/L) 18 NH3-N (mg/L) 10-15 102 250 30 . 0 4.8 2-3 23 10-20 72 210 30 0 4.7 3-3 . 5 23 10-15 250 50 0 4-4 . 5 3 20-30 59 4.1 Acclimation and Debugging, PP1 The sewage c o l l e c t e d on the two occasions during period PP1 (June 25-July 20) was weaker than the t y p i c a l averages of the p i l o t - p l a n t as shown i n Table 4.2. As a r e s u l t , the MLSS l e v e l decreased s t e a d i l y from the i n i t i a l p i l o t - p l a n t l e v e l of 2400 mg/L to 1800 mg/L as shown i n Figure 4.1. Due to the change i n chemical substrate addition from fermented primary sludge to an acetate-propionate mixture, the biomass may also have been undergoing a period of acclimation. Manoharan (1988) reported the a f f e c t s of changing substrate as varying from l i t t l e or no acclimation required to an almost complete change i n biomass. Some two to three weeks was required before e f f l u e n t P had decreased to low l e v e l s as seen i n Figure 4.2. Chemical pump d i f f i c u l t i e s i n the control module delayed the onset of low ef f l u e n t P l e v e l s by 10 days- the time i t took to restore chemical addition to proper l e v e l s . This seems to indicate that the sludge was acclimating to the new substrate and that the bio-P organisms were building up stores of carbon and phosphorus. Phosphorus release and uptake was depressed i n the control module while the chemical addition was r e s t r i c t e d . Release and uptake soon returned to s i m i l a r l e v e l s as the experimental module once the chemical addition was restored, as seen i n Figure 4.3. £_ to Q _l O CO Q LU Q 2 LU 0. CO CO _ l O 5000 4000 3000 2000 1000 X RICHMOND T FEED CHANGE t t AN HRT CHANGE PILOT-PLANT FEED CHANGE a CONTROL + EXPERIMENTAL 40 80 120 160 200 240 280 CUMULATIVE TIME (DAYS) Figure 4.1. Total Module Mixed Liquor Suspended Solids. Figure 4.2. Effluent Ortho-Phosphate as P. 40 -, 35 - 30 - E, • M O  25 - _ i U. H- 20 -Z HI 13 _ l 15 -U. 2 UJ 10 - w < UJ -1 5 -i UJ cc Cw 0 - RICHMOND i i PILOT-PLANT FEED CHANGE " " FEED CHANGE AN HRT CHANGE Q CONTROL + EXPERIMENTAL 120 160 200 CUMULATIVE TIME (DAYS) 240 280 Figure 4.3. Anaerobic Zone Phosphate Mass Release. P release in mg/h divided by influent flow in L/h — i — i — i — i — i — i — i — i — \ — i — i — i — 40 80 120 160 200 240 280 CUMULATIVE TIME (DAYS) Figure 4.4 Influent C O D 62 At the end of t h i s period, both modules were performing at very s i m i l a r l e v e l s . Influent COD had dropped to below 150 mg/L, however, so the feed was changed to Richmond sewage. 4.2 Base Line Conditions, Rl Shortly a f t e r the switch to Richmond sewage, with equipment operating properly, e f f l u e n t P dropped to near zero l e v e l s as seen i n Figure 4.2. During a two week period towards the end of the second month, ef f l u e n t P l e v e l s increased. This was p a r t l y due to highly variable feed COD and TP conditions, as indicated i n Figure 4.4 and 4.5. A more detailed d e s c r i p t i o n of those events w i l l take place i n section 5.1. During t h i s two month period, P removal (total-P i n the i n f l u e n t minus ortho-P i n the effluent) was more or less constant, as seen i n Figure 4.6. Towards the end of the t h i r d month, preparations for the f i r s t experimental change were made since e f f l u e n t P was steady at near zero l e v e l s for about f i v e weeks. At the beginning of the fourth month ef f l u e n t P l e v e l s increased to over 1 mg/L. As before, P removal was constant at about 4 mg/L. This point w i l l also be discussed i n more d e t a i l i n section 5.1. The processes were operated for another month before the f i r s t experimental change was made on November 3 (t=130 days). i R ICHMOND ± T F E E D C H A N G E T A N HRT C H A N G E i PILOT-PLANT T F E E D C H A N G E "V 40 80 120 ~160 200 240~ 280 CUMULATIVE TIME (DAYS) Figure 4.5. Influent Total Phosphate as P. at E 2 O 2 LU CC LU 1- < I CL co O I Cu 10 9 8 7 R I C H M O N D F E E D C H A N G E T A N HRT C H A N G E 4 PILOT-PLANT ' F E E D C H A N G E ° C O N T R O L * EXPERIMENTAL 40 80 120 160 200 CUMULATIVE TIME (DAYS) 240 gure 4.6. Phosphate Removal . Influent total phosphate minus effluent ortho-phosphate. 280 64 Ef f l u e n t P l e v e l s were i n the 0.2-0.5 mg/L range for most of t h i s l a s t month with P removal holding f a i r l y constant. The most important outcome to t h i s point was the s i m i l a r i t y between the two modules. The r e l a t i v e l y complex systems, composed of 6 reactors with 4 pumps, 2 recycle l i n e s and an a i r d i s t r i b u t i o n system feeding 4 reactors per module, were operated under s u f f i c i e n t l y s i m i l a r conditions as to perform almost i d e n t i c a l l y . Response to feed and operational upsets was also the same. Further proof of the s i m i l a r i t y between the two modules i s seen i n Figures 4.3, 4.7 and 4.8. This i s e s p e c i a l l y evident i n the anoxic and the aerobic reactors. The apparent steady state was anything but steady. The in t e r e s t i n g point was that no matter what the cause of the i r r e g u l a r i t i e s was, almost without exception, both modules responded the same. Clearly, both modules could be considered the same for the purposes of t h i s experiment. That i s to say, any differences between the two modules a f t e r the experimental change would be due to the change and not to any external factors. This assumes that a l l operational parameters such as DO, wasting rates, pumping rates and mixing regimes a l l remain within acceptable l i m i t s for both modules. Im p l i c i t to t h i s observation i s that the DO l e v e l s were close enough to not have an impact on the performance of the I 1 1 1 I I 1 1 1 1 1 1 1 1 1 0 40 80 120 160 200 240 280 •CUMULATIVE TIME (DAYS) Figure 4.7. Anoxic Phosphate Mass Release or Uptake. P release or uptake divided by influent flow. CUMULATIVE TIME (DAYS) Figure 4.8. Total Aerobic Zone Phosphate Mass Uptake. P uptake divided by influent flow. systems even though they d i f f e r e d between sides by 0.5-1.0 mg/L or more. Good P removal was observed when DO was r e l a t i v e l y low (0.5 mg/L) and when DO was much higher (2.0 mg/L or more). A comparison of P uptake rates i n each module, i n corresponding aerobic reactors did show some difference i n the P uptake rate when the DO l e v e l s d i f f e r e d by more than 0.5 mg/L. However, no differences were observed on other occasions when DO l e v e l s d i f f e r e d by more than 1.0 mg/L. Therefore i t i s d i f f i c u l t to specify the exact impact of varying DO, other than to assume that both modules were impacted i n the same fashion. Low DO l e v e l s did impact on the n i t r a t e + n i t r i t e (NOx) l e v e l s however. An attempt was being made to keep the DO low i n the f i r s t two aerobic reactors to prevent excessive oxidation. Aeration rates necessary to keep s o l i d s i n suspension would r e s u l t i n high (greater than 2.5 mg/L) DO l e v e l s i n the l a s t two aerobic reactors. Some s e t t l i n g , together with low DO l e v e l s , combined to give i n t e r n a l d e n i t r i f i c a t i o n within the aerobic zone while s t i l l maintaining complete ammonia oxidation. The e f f e c t s of low DO on the NOx l e v e l are seen i n Figure 4.9. From Figures 4.2 and 4.9, i t appears that the low NOx l e v e l s coincide with the anomalies i n the e f f l u e n t P l e v e l s . Furthermore, from a comparison of Figures 4.7 and 4.9 i t appears that low NOx l e v e l s coincide with net anoxic zone P release (at t=50-60 days, 80-90 days, and 110 days). R e l a t i v e l y high NOx l e v e l s coincide with net anoxic zone P uptake ( p r i o r to t=40 days, and at t=70 and 100 days). This i s consistent with the findings of Comeau et al.(1985), Rabinowitz (1985) and Wentzel et a l . (1986) who have shown NOx to be used as electron acceptors by bio-P bacteria. This a b i l i t y enables them to take up P under anoxic conditions. Once the NOx i s consumed, P i s then released for maintenance energy. P uptake and P release can both take place i n the anoxic zone. The net r e s u l t would depend on the system i n guestion, including the biomass, the amount of NOx recycled back to the anoxic zone and the anoxic zone HRT. The c y c l i n g from P release to P uptake to P release i n the anoxic zone c l e a r l y demonstrates t h i s p r i n c i p l e . Although i n f l u e n t and operating conditions were not as steady as expected, the three P p r o f i l e s i n Figure 4.10 show that both modules s t i l l responded i n the same fashion. E f f l u e n t P, P removal, P uptake and release, P p r o f i l e s and s o l i d s percent P (Figure 4.2, 4.6, 4.7, 4.8, 4.3, 4.10 and 4.11 respectively) were a l l the same for both modules during the base period (Rl). Other parameters such as TSS, NOx, and COD were also the same as seen i n Figures 4.1, 4.4 and 4.9. I t i s cle a r then that within the v a r i a t i o n of inf l u e n t and operating conditions, both modules responded i n e s s e n t i a l l y the same fashion. Therefore, any change i n the way the two sides responded a f t e r the anaerobic HRT change would be due to the change i t s e l f , provided that the same range of differences i n in f l u e n t and operating conditions was maintained. CUMULATIVE TIME (DAYS) Figure 4.9. Filtered Effluent Nitrate Plus Nitrite. a. JULY 10th (T=31 DAYS) b. OCTOBER 8th (T=104 DAYS) °CONTROL EXPERIMENTAL] AE1 AE2 REACTOR AE3 AE4 c. OCTOBER 12th fT= 108 DAYS) Figure 4.10. Phosphate Profiles. 10 - 9 - AN HRT l CHANGE ' r f PILOT-PLANT ' FEED CHANGE 8 - 7 J 6 - 5 - 4 - 3 - 2 - 1 - ° CONTROL %P o - 1 1 1 1 1 1 — + EXPERIMENTAL %P — I 1 1 , 1 1 1 40 80 120 160 200 240 CUMULATIVE TIME (DAYS) 280 Figure 4.11. Percent Phosphate as P in Dry Sol ids. 20 H RICHMOND ± FEED CHANGE Y AN HRT CHANGE t PILOT-PLANT FEED CHANGE -I 1 p 1 1 1 1 1 1 1 1 1 1 — 40 80 120 160 200 240 280 CUMULATIVE TIME (DAYS) Figure 4.12. Influent Total Kjeldahl Nitrogen 71 Influent Total Kjeldahl Nitrogen (TKN) (Figure 4.12) varied between 15 and 3 0 mg/L during t h i s period, without v i s i b l e e f f e c t s on process performance. S i m i l a r l y , i n f l u e n t soluble ammonia (Figure 4.13) varied between 11 and 27 mg/L during t h i s period. Extremes of the COD/TKN r a t i o ranged from 8 to 20 with most values between 10 and 15. Ekama et al.(1983) reported that the UCT process, as operated i n t h i s experiment, i s suited to t h i s range of COD/TKN values. These values were also i n the range that Manoharan (1988) reported i n h i s work. Consequently, the e f f l u e n t NOx values, and therefore the NOx loading to the anoxic zone, were s i m i l a r to values reported by Manoharan. 4.3 E f f e c t of the Anaerobic HRT Change, R2 4.3.1. R2 Period On November 3 (t=130 days) the mixed l i q u o r from both modules was drained from the bioreactors and combined. At the same time the experimental module anaerobic reactor was reduced i n volume by r a i s i n g the base of the anaerobic reactor as described i n Section 3.3. The mixed material was then returned to the two bioreactors. TSS measurements l a t e r showed that the mass of sludge i n each module was within 5%. The 50% reduction i n the anaerobic volume and HRT reduced the o v e r a l l experimental module bioreactor volume by less than 10%. To maintain the same SRT, wastage was reduced accordingly, r e s u l t i n g i n a difference cn E in co 2 < I- Z HI Q UJ cc 50 40 30 20 10 w RICHMOND T F E E D C H A N G E A N HRT C H A N G E w PILOT-PLANT T F E E D C H A N G E i 1— 40 i 1 — 80 120 160 200 240 C U M U L A T I V E TIME (DAYS) 1 1 1 r- 160 200 280 Figure 4.13. Filtered Influent Ammonia. cn £. Q O CD $ Q 200 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 4 RICHMOND I T F E E D C H A N G E » PILOT-PLANT F E E D C H A N G E A N H R T C H A N G E Total Soluble 1 1 1 1 1 1 1 1 1 1 1 1 1 — 40 80 120 160 200 240 280 C U M U L A T I V E TIME (DAYS) Figure 4.14. Influent Total and Soluble 5 Day BOD. 73 of 10-15 mL per day i n wastage rate from each of the two modules. No other changes were made. Any difference i n e f f l u e n t q u a l i t y between the two modules would have been attributed to the anaerobic change, however no change i n e f f l u e n t P was observed. Both modules cycled between low and high e f f l u e n t P values several times but they did so i n unison, as seen i n Figure 4.2. I t appeared that a f t e r 4 0 days of these observations, both modules s t i l l performed the same. There were differences, however with the amount of anaerobic P release, shown i n Figure 4.3, being the most noticeable. The amount of P released i n the anaerobic zone of the experimental module was 20-30% less than the amount of P released i n the anaerobic zone of the control module. Correspondingly, Figure 4.8 shows that less P was taken up i n the experimental module aerobic zone, but only 10-15 % l e s s . Since P was not l i m i t i n g , an improvement i n the o v e r a l l P removal performance of the experimental module would have been expected, but Figure 4.6 shows both modules remained the same. An explanation was found by looking at the anoxic zone. Consistently, ei t h e r less P was taken up i n the anoxic zone of the experimental module or more P was released, as seen i n Figure 4.7. The r e s u l t s for the anaerobic and aerobic zone are i n agreement with batch tests done by Comeau et a l . (1985) and Rabinowitz (1985) who showed that more anaerobic P release 74 generally led to more aerobic P uptake. Work on a continuous process by Manoharan (1988) indicated that the amount of aerobic P uptake i s related to the amount of anaerobic P release, with the anoxic zone sometimes showing a net P release and sometimes a net P uptake. The anoxic zone w i l l be discussed i n greater d e t a i l i n section 5.2. During t h i s 40 day R2 period, a f t e r the experimental module anaerobic HRT was reduced, the P removal performance and e f f l u e n t P l e v e l s had degenerated i n both modules. Furthermore, the e f f l u e n t P l e v e l s and P removal performance were very variable, as seen i n Figures 4.2 and 4.6. The sewage was suspected of containing high l e v e l s of metals such as chromium. One t e s t showed a chromium concentration of 0.5 mg/L. Therefore i t was decided to switch back to p i l o t - p l a n t sewage. 4.3.2 E f f e c t of Anaerobic HRT Change, PP2 Interestingly, within two weeks of changing to p i l o t - p l a n t sewage, the two modules began to show differences i n P removal (Figure 4.6) and e f f l u e n t P l e v e l s (Figure 4.2)- for the f i r s t time during t h i s experiment. On occasions, the two modules showed s i m i l a r P l e v e l s and P removals but t h i s was during periods of high e f f l u e n t P l e v e l s i n both modules. For the duration of the experiment-more than 100 days- a d e f i n i t e 0.5 to 1.0 mg/L difference i n P removal and e f f l u e n t P l e v e l s persisted. A l l operating parameters were maintained within a 75 range of v a r i a t i o n which were shown, during the base period, not to a f f e c t the ef f l u e n t P le v e l s or P removal performances of the two process t r a i n s . The difference could only be attr i b u t e d to the difference i n the anaerobic HRT's of the two modules. The explanation w i l l be presented i n section 5.4. Another i n t e r e s t i n g observation was the seemingly c y c l i c nature of the effl u e n t P l e v e l s i n both modules while using p i l o t - p l a n t sewage. The only variable which could have such an impact was the feed. Other variables such as DO and pumping rates did not show any c y c l i c v a r i a t i o n s . The feed sewage was changed every three weeks or less i n an attempt to prevent the feed c h a r a c t e r i s t i c s from changing s i g n i f i c a n t l y while i n the cold room. Although no feed c h a r a c t e r i s t i c s remained p e r f e c t l y stable, the only factor which varied i n a c y c l i c fashion was the carbon content, as measured by the t r a d i t i o n a l means of COD, BOD5, TOC and VFA as seen i n Figures 4.4, 4.14, 4.15 and 4.16 respectively. In general, the carbon content was higher i n fresh feed j u s t obtained from the p i l o t - p l a n t than i n the feed which had been i n storage f o r one week or more- e s p e c i a l l y as measured by BOD5. COD and TOC also varied i n a c y c l i c fashion but the percent reduction while i n cold storage was i n the 10-30% range compared to the 30-50% range for BOD5. This i s evident i n Figures 4.4, 4.14 and 4.15. There appears to be a lack of c o r r e l a t i o n between i n f l u e n t 50 40 30 20 H 10 A . / \ V i RICHMOND * FEED CHANGE AN HRT CHANGE A A PILOT-PLANT FEED CHANGE 40 80 120 160 200 CUMULATIVE TIME (DAYS) 240 Figure 4.15. Influent Total Organic Carbon . (measured in the influent bucket) 280 cr so 40 30 20 H 10 X I PILOT-PLANT T FEED CHANGE 40 80 120 160 200 CUMULATIVE TIME (DAYS) 240 280 Figure 4.16. Influent Volatile Fatty Ac id Concentrat ion, (as measured in the influent bucket) BOD5 and e f f l u e n t P. A s t a t i s t i c a l analysis of i n f l u e n t BOD5 and e f f l u e n t P resulted i n an R squared factor of 0.03. A comparison of Figures 4.2 and 4.14 however, shows that a change i n the trend of i n f l u e n t BOD5 strength i s often associated with a change i n the trend of e f f l u e n t P. For example, i f there was an increase i n i n f l u e n t BODc the e f f l u e n t P l e v e l s would drop within a few days. Some lag time between i n f l u e n t BOD5 changes and e f f l u e n t P trends was usually noted. In some cases, other wastewater c h a r a c t e r i s t i c s , DO l e v e l s , process upsets and sampling frequency may have obscured the e f f e c t . For the most part however, e f f l u e n t P was affected by the i n f l u e n t feed strength as measured by BOD5 or COD. This i s well documented i n the l i t e r a t u r e , which reports the detrimental e f f e c t s of low i n f l u e n t organic feed strength. Fukase et a l . (1985), Rensink et a l . (1981), and N i c h o l l s and Osborn (1979), to name a few, have a l l reported t h i s . While the feed strength could be singled out to be the only factor responsible for the c y c l i c e f f l u e n t P l e v e l s , i t alone did not explain the changing degree of P removal. The lack of any c o r r e l a t i o n between the BOD5 or COD value and the e f f l u e n t P or P removal i s adequate evidence. One obvious explanation might be that B0D5 and COD are too crude, measuring more than j u s t the type of carbon which i s important i n bio-P treatment, such as VFA's or r e a d i l y biodegradable carbon. 78 4.4 Additional Tests, PP2 The P mass flow rate through the anoxic zone also appeared to be c y c l i c i n nature as seen i n Figure 4.7. A comparison of the P p r o f i l e s i n Figures 4.10 and 4.17 i l l u s t r a t e the e f f e c t of the anaerobic HRT change . These figures are representative of p r o f i l e s during the baseline period (Rl) and the period just a f t e r the anaerobic HRT was changed (R2), respectively. Pr i o r to the anaerobic HRT change, the P p r o f i l e s were almost i d e n t i c a l , i n d i c a t i n g the same performance. Immediately a f t e r the change, while using Richmond feed, the only difference between the P p r o f i l e s was that the anaerobic P l e v e l s were much lower i n the experimental module than i n the control module. Af t e r the anoxic zone, however, P l e v e l s were once again the same fo r both modules. Therefore, the anoxic zone of the experimental module simply was not functioning "as wel l " as the anoxic zone of the control module. I t seemed that an improved P removal, or the same P removal i n fewer aerobic reactors, should have been achievable j u s t as the i n i t i a l hypothesis suggested, except f o r the performance of the anoxic zone. When p i l o t - p l a n t feed was used, both the anoxic zone and the aerobic zone were affected, as seen i n Figure 4.18. In summary, with Richmond feed, the change i n anaerobic HRT seemed mainly to a f f e c t the anoxic zone performance. When p i l o t - p l a n t feed was used, the aerobic zone was also affected. C l e a r l y then, the difference i n anoxic zone performance had to cn £ CO ra < I CL CO O X a. 6 x t- cc O 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 S 4 3 2 1 0 AN ° C O N T R O L - EXPERIMENTAL AX AE1 AE2 R E A C T O R AE3 AE4 Figure 4.17. Phosphate Profile for November 23rd. (T=150 days) cn E cn CD UJ I CL co O X CL 6 X t- cc o 20 19 18 17 16 15 14 13 12 11 7 6 5 4 3 2 1 0 cn E CO CO UJ X 0_ CO o X CL 6 I I- tr O a CONTROL .^^ EXPERIMENTAL AN AX AE1 AE2 AE3 AE4 R E A C T O R a. MARCH 22nd (T=270 DAYS) 20 19 18 17 16 H 15 14 13 H 12 a CONTROL + EXPERIMENTAL AE3 AE4 R E A C T O R b. MARCH 23rd (7=271 DAYS) Figure 4.18. Phosphate Profiles be a t t r i b u t e d to the anaerobic HRT difference. Differences i n the aerobic zone had to be due to the feed differences or the anaerobic HRT differences compounded by differences i n the feed. To sort out these problems, a comprehensive program of d a i l y feed and ef f l u e n t t e s t i n g was undertaken together with two sets of batch t e s t s . 4.4.1. Daily Testing, PP2 As noted previously, c y c l i c v a r i a t i o n s i n the e f f l u e n t P le v e l s were related to the feed strength . During the l a s t month of experimentation, samples of the feed were taken from the storage carboys while s t i l l i n the cold room. F i l t e r e d COD, TOC, VFA and ortho-P measurements were made as well as occasional BOD5 measurements. This period was not t y p i c a l of the previous two to four months, however, i n that the e f f l u e n t P var i a t i o n s and the in f l u e n t feed strength v a r i a t i o n s were not as dynamic. F i r s t , BOD5, COD and TOC a l l remained f a i r l y constant throughout t h i s batch of sewage as seen i n Figures 4.19, 4.20 and 4.21. Differences were noted when the sewage was changed. As a r e s u l t , e f f l u e n t P, while not constant, did not show the extreme range of var i a t i o n s noted previously. Again, higher COD, BOD5 or TOC feed did not necessarily lead to improved P removal as seen i n Figure 4.22. FEED CHANGE I o TOTAL BOD * SOLUBLE BOD 248 252 256 260 264 268 CUMULATIVE TIME (DAYS) Figure 4.19. Total and Soluble 5 Day BOD. Sampled in storage 272 276 300 276 CUMULATIVE TIME (DAYS) Figure 4.20. Total and Soluble COD. Sampled in Storage 100 90 - 80 - 70 - 60 - 50 - 40 30 -' 20 - 10 - 0 ' FEED T CHANGE i FEED T CHANGE ° SAMPLED IN STORAGE + SAMPLED IN FEED 248 252 256 260 264 268 CUMULATIVE TIME (DAYS) 272 276 Figure 4.21. Influent Total Organic Carbon . Figure 4.22. Phosphate Removal . Influent Total-P as P Minus Effluent Ortho-P as P. 83 Second, the increase i n VFA's i n the feed, with time, while i n cold storage, was i n t e r e s t i n g . Figure 4.23 shows a short lag period existed p r i o r to a steady increase i n VFA l e v e l during cold storage. Furthermore, t h i s was only observed when the sample was taken p r i o r to transfer to the i n f l u e n t bucket. Samples from the i n f l u e n t bucket showed occasional peaks of VFA's only. This may be because of VFA a s s i m i l a t i o n by biomass i n the i n f l u e n t bucket under aerobic conditions. Aerobic conditions occur temporarily j u s t a f t e r f i l l i n g with fresh i n f l u e n t and when the i n f l u e n t bucket was nearly empty. Since the i n f l u e n t bucket was the sampling point for VFAs, i t i s possible that the b r i e f aerobic conditions resulted i n some VFA uptake. This could cause the VFA concentration to be under estimated at the time of sampling compared to the average d a i l y batch concentration. Since VFA's were routinely sampled i n the i n f l u e n t bucket they were often not detected or t h e i r concentration was underestimated. The e f f e c t s of generated VFA's may have s p i l l e d over to the anaerobic reactors of both modules. Figures 4.23 and 4.24 shows that the detection of excess VFA's i n the anaerobic reactors coincides with increased fresh feed VFA l e v e l s . I t i s not s u r p r i s i n g then that the shorter anaerobic zone may have been more e a s i l y overloaded with VFA's. I t i s possible that these excess VFA's also affected the anoxic zone performance. Batch te s t s were therefore run to explain t h i s matter. — 1 — I U i p m L p — i 1 1 1 1 1 1 r 1 — L H— | — m — t p — i 1 r—| 1 252 256 260 264 268 272 276 CUMULATIVE TIME (DAYS) Figure 4.23. Influent Volatile Fatty Ac ids . 248 252 256 260 264 268 272 276 CUMULATIVE TIME (DAYS) Figure 4.24. Anaerobic Effluent Volatile Fatty Ac id . 85 4.4.2. Batch Tests, PP2 P r i o r to running the batch t e s t s , several p o s s i b i l i t i e s were put f o r t h to explain the difference i n the anoxic zone P performance between the two modules. The p o s s i b i l i t y of excess VFA's passing from the anaerobic zone to the anoxic zone, i n the experimental module was noted. Some carbon storage and P release would s t i l l take place i n the anoxic zone. Competition for the VFA's by d e n i t r i f i e r s i n the anoxic zone, however would r e s u l t i n an o v e r a l l reduction i n the amount of PHA stored; thus leading to a reduction i n o v e r a l l P uptake c a p a b i l i t i e s and hence a reduction i n P removal. This speculation i s supported by the research r e s u l t s of Manoharan (1988), Comeau (1984), Rabinowitz (1985), Gerber et a l . (1987) etc. Gerber et a l . (1987) s p e c i f i c a l l y stated that any carry-over of VFA's to the anoxic zone would have a detrimental e f f e c t on the o v e r a l l P removal. Another p o s s i b i l i t y which may have impacted on the anoxic zone performance, eith e r independently or simultaneously, was the increase i n the d e n i t r i f i c a t i o n rate due to the carry-over of simple substrate from the anaerobic zone. This resulted i n more retention time i n the absence of NOx and hence more P release needed for maintenance energy. Gerber et al.(1987) also c l e a r l y i l l u s t r a t e d t h i s P uptake/P release phenomena i n the presence and subsequent absence of NOx i n the anoxic zone. 86 The e f f e c t of feed strength or s e p t i c i t y may also have had an impact on the anoxic zone performance. To t e s t for t h i s , two sets of batch t e s t s were run: the f i r s t with feed which had been stored i n the cold room for eighteen days; and the second with feed which had been stored i n the cold room for about ten days. The COD and BOD of the feed i s l i s t e d i n Table 4.3. Figure 4.25 shows the fate of P04-P, NOx-N and PHA as PHB during the batch t e s t s . The second batch t e s t on the control module was ruined, l i k e l y due to a i r entrainment. This was very obvious from the r e s u l t s , so a repeat was run two days l a t e r , which appeared more reasonable and i s reported here. Occasionally, VFA's were detected i n the anaerobic zone of the experimental module during the continuous flow t e s t i n g . I t would have been i n t e r e s t i n g to see the a f f e c t of VFA's c a r r i e d over from the anaerobic zone to the anoxic zone on P04, PHA, and NOx. However, because of the low concentration of VFA's i n the anaerobic zone and the pot e n t i a l for rapid a s s i m i l a t i o n when mixed with the c l a r i f i e r underflow MLSS, no VFA's were detected i n the anoxic zone batch t e s t even at t=0. No impact of VFA's on P04, PHA, or NOx i s evident i n Figure 4.25. In the f i r s t batch t e s t , the d e n i t r i f i c a t i o n rates were approximately the same for the control and experimental f l a s k s . The r e s u l t s indicated that the f u l l 90 minute anoxic HRT i n the 8 7 Table 4.3 Summary of Feed, Anaerobic and C l a r i f i e r Underflow C h a r a c t e r i s t i c s for the Batch Te s t s Feed Anaerobic C l a r i f i e r Zone Underflow Days Total Total PHA as PHA as Stored COD B0D5 P04-P PHB NOx-N P04-P PHB NOx-M (days) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Batch Test #1 Con. 18 178 50 11.3 16.5 0 1.5 5.4 9 . 1 Exp. 18 178 50 8.3 14.8 0 1.9 5.9 9 . 1 Batch Test #2 Con. 11 189 75 — 16.4 — 1.6 5.7 Exp. 9 213 90 8.5 15.9 0 2.6 4.9 8.2 Table 4.4 Phosphate Mass Balances Before and Af t e r Mixing Sludges Date Control Module Experimental Module An Ax Ae E f f An Ax Ae E f f Before Mixing Mar. 21 14.6 -5.3 -13.0 1.0 6.7 -2.2 -7.2 2.0 1988 After Mixing Mar. 23 11.8 -5.1 -9.8 1.7 8.2 -2.5 -8.6 1.9 1988 Mar. 24 12.2 -3.9 -11.4 1.7 8.4 -2.6 -8.4 2.2 1988 mass balance units, mg/L = mg/h = mass balance L/h i n f l u e n t Q po s i t i v e = P released to solut i o n negative = P taken up from solu t i o n 20 -y 19 - 18 - 0 20 40 60 80 100 120 TIME (MIN) a. B A T C H T E S T #1 C O N T R O L M O D U L E TIME (MIN) b. BATCH TEST #1 EXPERIMENTAL MODULE Figure 4.25. Batch Tests Results for Test #1 .7 19 - oi 18 - TIME (MIN) C. BATCH TEST #2 CONTROL MODULE Figure 4.25. Batch Test Results for Test #2 flow-through reactor would be required for complete d e n i t r i f i c a t i o n . The net or observable P uptake rate was higher for the control module flask, which i s consistent with continuous flow data. P uptake, P release and d e n i t r i f i c a t i o n i n both fl a s k s was l i n e a r . Gerber et a l . (1987) have produced almost the same re s u l t s i n one of t h e i r t e s t s . During both t e s t s , NOx loading was more or l e s s constant, with about a 10% lower load during the second t e s t . I t seems that the net e f f e c t on P uptake and release i s therefore dependent on the feed strength, which, i n turn, seems to have an impact on the d e n i t r i f i c a t i o n rate. This would also i n turn impact on the amount of P release a f t e r d e n i t r i f i c a t i o n was complete. PHA measurements did l i t t l e to further explain the differences between the two f l a s k s because of the v a r i a t i o n from point to point. The general trend, however, was towards a decrease with time while NOx was present and then l i t t l e or no change thereafter. Comeau et a l . (1985) and Comeau et a l . (1986) report a s i m i l a r finding, although the fate of PHA a f t e r complete d e n i t r i f i c a t i o n i s also not c l e a r i n t h e i r report. In summary, PHA was consumed during anoxic zone d e n i t r i f i c a t i o n and P was taken up simultaneously. A f t e r d e n i t r i f i c a t i o n was complete, PHA consumption ceased and P release began. The impact that VFA's had on the anoxic zone was not evident from the data. There was a d e f i n i t e change i n d e n i t r i f i c a t i o n rate with a change i n feed strength or feed storage time i n the cold room. One r e s u l t which could not be explained by feed strength, was the P uptake rate differences between the two fl a s k s i n the second set of batch t e s t s . The P uptake rate i n the control and experimental flasks was 0.021 and 0.013 mg/L/d per mg VSS, respectively. The two tests were under s i m i l a r conditions. One explanation proposed was that the number (or mass) of bio-P type organisms was greater i n the control f l a s k . This seems possible since the s e l e c t i o n process for enhancement of the bio-P organisms i s a r e s u l t of bio-P organisms being able to consume a l l (or most) of the "desirable" organic materials i n the i n f l u e n t sewage. This desirable material includes both the r e a d i l y biodegradable f r a c t i o n of the sewage plus any added VFA's. I t has already been reported that some of the VFA's were escaping the anaerobic zone of the experimental module. VFA's could therefore become available to non-phosphorus stori n g heterotorphs i n the anoxic zone, which would r e s u l t i n a loss of competitiveness and hence a decrease i n o v e r a l l numbers (or mass) of bio-P organisms i n the experimental module. This i s i n l i n e with the findings of Rensink et a l . (1981). 92 4.4.3 Mix Sludges Test, PP2 To t e s t the p o s s i b i l i t y that more bio-P organisms were present i n the control module, one f i n a l t e s t was conducted. The mixed-liquor from both modules was combined and r e d i s t r i b u t e d . Analyses continued on a d a i l y basis p r i o r to and a f t e r the mixing to see i f any changes took place - e s p e c i a l l y i n P mass balances across the three reactor zones. The r e s u l t s are tabulated i n Table 4.4 and i l l u s t r a t e d i n Figure 4.18. Two points are noted. F i r s t , there was some amount of equalization i n the process e f f i c i e n c y due to the mixing of the sludges. This c l e a r l y proves that a d i f f e r e n t mix of bio-P organisms had developed i n the two modules. This difference can be attributed to a reduction i n the anaerobic HRT, leakage of VFA's to the anoxic zone due to a reduced anaerobic HRT, or both. A discussion of t h i s w i l l take place i n section 5.3. Second, regardless of the differences which developed, when both modules had approximately the same microbial make-up ( i e . a f t e r mixing), a difference i n process e f f i c i e n c y was s t i l l evident. This difference existed, not only i n the amount of anaerobic P release (Figure 4.3) and the amount of anoxic and aerobic P uptake (Figures 4.7 and 4.8), but also i n the e f f l u e n t P l e v e l s (Figure 4.2). These differences are also evident i n Table 4.4. This i s evidence of the impact that the reduced anaerobic HRT had on the performance of the process, eit h e r d i r e c t l y , or i n d i r e c t l y as a r e s u l t of a leakage of VFA's to the anoxic zone. Summarizing, the change i n anaerobic HRT impacted on the process performance either d i r e c t l y or i n d i r e c t l y by reducing the bio-P competitiveness r e s u l t i n g i n fewer bio-P organisms. It also affected the amount of P release, which i s i n d i c a t i v e of the amount of carbon storage taking place. As a r e s u l t , the amount of P uptake and P removal was reduced. 94 Chapter 5. Discussion of Results The research project was directed at improving the performance of the b i o l o g i c a l phosphorus removal process i n general and i n p a r t i c u l a r the UCT type process. The discussion w i l l be focused on the factors which affected the process and which may ultimately allow for an improvement i n the design and /or operation of the bio-P plants. 5.1 Anomalies A discussion of some of the apparently anomalous r e s u l t s i n t h i s research w i l l help to explain the interactions taking place within the bio-P process. 5.1.1. Anomaly 1 The f i r s t took place on August 17th at t=52 days. The feed was l a s t changed about 4 weeks before when the switch to Richmond sewage was made. By August 17th, VFA's had b u i l t up i n the stored sewage. Eff l u e n t ortho-P concentrations rose to 9 mg/L i n the control side. Two operating c h a r a c t e r i s t i c s were found to have changed concomitantly with t h i s r e s u l t . The two factors were high concentrations of VFA i n the feed (20 mg/L) and low e f f l u e n t NOx l e v e l s (3.8 and 7.8 mg/L i n the control and experimental modules, re s p e c t i v e l y ) . Both modules were impacted by t h i s surge i n feed VFA strength which led to measured anaerobic VFA l e v e l s of 12-13 mg/L, as seen i n Figure 5.1. The difference i n e f f l u e n t NOx l e v e l s , however, led to a difference i n o v e r a l l P removal for that day. The t o t a l mass of P04-P entering the anaerobic and anoxic zones of the bioreactors on that day i n the control module were 7 and 30 mg/L respectively (measured as mg P04-P per l i t r e of i n f l u e n t flow). In the experimental module, values were 14 and 18 mg/L, respectively. Typical values for both modules were 18 and 0 (±6) mg/L for the anaerobic and anoxic zones, respectively. Total P release and P uptake were very s i m i l a r for both modules, the difference being i n which zone the P release took place. Both modules were affected by high VFA's i n the feed, which led to high VFA's i n the completely mixed anaerobic zone (no measurements were made for VFA's i n the anoxic zone, although they would l i k e l y be undetected a f t e r the 90 minute actual HRT). This excess, upon entering the anoxic zone, may have increased the d e n i t r i f i c a t i o n rate leaving even more time f o r secondary P release. A lower NOx load entering the anoxic zone of the control module further compounded the e f f e c t , since even more time f o r secondary release was possible. Two factors would lead to the higher control module anoxic zone P release: f i r s t , there was less P uptake due to less NOx available; second, there was more time f o r P release again, due to less NOx present i n the 20 19 - 18 - 17 - 16 - 15 - 14 - 13 - 12 - 11 - 10 - 9 - 8 - 7 - 6 - 5 - 4 - 3 - 2 - 1 - 0 0 | RICHMOND y FEED CHANGE T AN HRT CHANGE PILOT-PLANT FEED CHANGE 160 200 240 40 80 120 CUMULATIVE TIME (DAYS) 280 a. CONTROL MODULE 20 19 - 18 - 17 - 16 - 15 - 14 - 13 - 12 - 11 - 10 - 9 -8 - 7 - 6 - 5 - 4 -3 - 2 - 1 - 0 0 RICHMOND FEED CHANGE PILOT-PLANT FEED CHANGE AN HRT CHANGE JA 40 80 120 160 200 240 280 CUMULATIVE TIME (DAYS) b. EXPERIMENTAL MODULE ure 5.1 Anaerobic Effluent Volatile Fatty Ac id Concentrat ions in the Control and Experimental Modules 9 7 anoxic zone. I t i s i n t e r e s t i n g also to speculate on why the anaerobic P release was reduced so much below normal, e s p e c i a l l y i n the control module. In work done by Manoharan (1988), an increase i n feed VFA's led to an increase i n anaerobic P release and an increase i n o v e r a l l P removal. The difference however, was that Manoharan had an acclimated biomass and was adding more VFA's on a continuous basis, not on a spike type basis. An examination of the e f f e c t of t h i s spike, s t a r t i n g at the anoxic zone, w i l l explain the cause-effect rela t i o n s h i p s . Biomass enters the anoxic zone from the c l a r i f i e r underflow, where i t normally has r e l a t i v e l y low carbon reserves. Furthermore, the biomass possesses r e l a t i v e l y high P reserves. In the anoxic zone, any VFA's bleeding through from the anaerobic zone are consumed, P i s released and carbon (PHA) i s stored. Some simultaneous or subsequent P uptake i n the presence of NOx may also take place followed by secondary P release i n the absence of NOx. Recycle of t h i s biomass to the anaerobic zone i s normally r e l a t i v e l y high i n P reserves and r e l a t i v e l y low i n PHA reserves. I t i s a c t u a l l y a 2:1 mass mix of previously aerobic (sludge-underflow) and previously anaerobic biomass based on the recycle rates used i n t h i s experiment. During t h i s upset however, the biomass has had an opportunity to store a considerable amount of PHA i n the anoxic zone. Therefore, the 98 biomass recycled to the anaerobic zone would be lower i n P reserves and higher i n C reserves than normal. Under these conditions, the biomass would have a reduced capacity to u t i l i z e the VFA's i n the anaerobic zone. In other words, the anaerobic release may be P l i m i t i n g . Therefore, P release would decrease, VFA's discharged to the anoxic zone would increase and net P release i n the anoxic zone would increase. The problem therefore compounds i t s e l f . I t i s c l e a r that a short term increase i n VFA's w i l l overload the anaerobic zone, r e s u l t i n g i n a carry-over to the anoxic zone. More bio-P type organisms would eventually develop to take up the slack i f the addition of more VFA's were on a continuous basis. The above p o t e n t i a l l y explains the detrimental e f f e c t of short term increases i n the VFA load to the bio-P process, as pointed out by Gerber et a l . (1987). The lower NOx load to the control side further compounded the e f f e c t . High VFA's were detected i n the feed on several other occasions, however, none had the same impact, apparently due to the fact that most of the excess VFA's were s t i l l being removed from solu t i o n within the anaerobic zone v i a greater storage i n the bio-P organisms. 99 5.1.2. Anomaly 2 The next anomaly started on September 21 (t=87d). A strong rotten egg smell from the sewage was noted at that time. Therefore, reduced sulphur species may have been the cause of the anomaly. Comeau et a l (1985) and Comeau et a l (1986) reported the e f f e c t s of H2S (and C02) on P release. H2S w i l l stimulate the release of P i n the anaerobic zone but without the associated carbon storage. This could a f f e c t the process i n two ways. F i r s t , more P must be taken up i n the subsequent anoxic and aerobic zones and second, there may be even less t o t a l carbon stored than normal. During t h i s period, the P uptake rate was reduced, which may be due to lower carbon reserves. This period was also characterized by low NOx l e v e l s i n the e f f l u e n t , so anoxic P uptake was less than normal. Together, the higher anoxic P concentrations and lower aerobic P uptake rate combined to give high e f f l u e n t P values. A change of feed was associated with a return to t y p i c a l e f f l u e n t P l e v e l s . As a r e s u l t of t h i s incident, feed was changed every 3 weeks to prevent excess s e p t i c i t y . 5.1.3. Anomaly 3 A high e f f l u e n t P peak was observed on November 17th (t=144 days). Anaerobic P release rates were down by 25% for that day. Aerobic P uptake rates were also low. 100 The feed being used p r i o r to November 17th was p a r t i c u l a r l y high i n TKN and NH3 as seen i n Figures 4.12 and 4.13. Like a l l Richmond feed, the raw sewage had to be d i l u t e d with tap water to an average in f l u e n t COD value of about 250 mg/L. Due to COD reduction while i n the cold room, weekly d i l u t i o n r a t i o s were reduced, r e s u l t i n g i n the higher measured TKN and NH3 feed strength. This resulted i n increased e f f l u e n t NOx l e v e l s recycled to the anoxic zone. As a r e s u l t , about 45% of the t o t a l P uptake occurred i n the anoxic zone. According to the r e s u l t s of Comeau et a l . (1987), more P i s accumulated per mole of PHA consumed when oxygen i s the electron acceptor instead of n i t r a t e . Therefore, i f a substantial amount of the P uptake took place i n the anoxic zone, there may be proportionately less PHA remaining f o r P uptake i n the aerobic zone. This period was characterized by lower than normal P uptake rates i n the anoxic and aerobic zones. I t i s possible that the quantity of PHA reserves not only a f f e c t the amount but also a f f e c t the rate of P uptake. Times when anaerobic P release was high and anoxic P uptake was low tend to show higher than normal P uptake rates. Typical P p r o f i l e s for each, appears i n Figures 4.17 and 4.18. 5.2. Bio-P Mechanisms A point by point review of anaerobic P release (Figure 4.3) and e f f l u e n t P (Figure 4.2) during the period when p i l o t - p l a n t sewage was used, shows that for the most part, an increase i n anaerobic P release corresponded to a decrease i n e f f l u e n t P. In Figure 5.2, the anoxic P release and the anaerobic P release were added to give t o t a l P release. Comparing Figures 5.2 and 4.3 with Figure 4.2 i t appears that the high P release peaks, which correspond to low e f f l u e n t P, are even more pronounced for t o t a l P release than for anaerobic P release alone. Noticing also that aerobic P uptake (Figure 4.8) was higher when t o t a l P release was higher, i t can be concluded that t h i s extra P release under anoxic conditions has, at l e a s t i n some instances, contributed to improved P removal ( i e . i t i s not a l l secondary release). Total P release, however, did not correlate to e f f l u e n t P as well as anaerobic P release alone. The R squared factor was 0.4 for t o t a l P release and 0.5 for anaerobic P release. Early i n the study, P p r o f i l e s , such as the one i n Figure 4.10a, showed the aerobic zone to be more than double the s i z e necessary to reduce P l e v e l s to below 0.5 mg/L. At the time these p r o f i l e s were obtained, the biomass was increasing due to an increase i n feed strength (Figure 4.1). By the time "steady state" was reached, the aerobic P uptake rate had dropped by 30-40 % (Figure 4.10b and 4.10c). From t h i s time on, P was taken up i n a l l aerobic reactors. The P p r o f i l e s , showing the P uptake rates, varied between the two extreme cases shown i n Figure 4.10b and 4.10c. Two i n t e r e s t i n g observations can be made from the two P CUMULATIVE TIME (DAYS) a. ANAEROBIC+ANOXIC PHOSPHATE MASS RELEASE as P vs EFFLUENT PHOSPHATE as P. CUMULATIVE TIME (DAYS) b. ANAEROBIC PHOSPHATE MASS RELEASE as P vs EFFLUENT PHOSPHATE as P Figure 5.2 ANAEROBIC and ANAEROBIC+ANOXIC PHOSPHATE RELEASE as P vs EFFLUENT PHOSPHATE as P-CONTROL MODULE 103 p r o f i l e s . F i r s t , there i s a connection between the anoxic and aerobic P uptake rates. Comparing times when anaerobic P storage was the same, (eg t=lll-125 days and t=230-237 days) an increase i n the amount of P taken up i n the anoxic zone was associated with a decrease i n the amount and the rate of P uptake i n the aerobic zone. The reverse was also true. This implies that there i s some f i n i t e quantity c o n t r o l l i n g or r e s t r i c t i n g the t o t a l amount of P uptake. Comeau et a l . (1987) suggest that the PHA reserves are the l i m i t i n g factor. Over a long period where the day to day v a r i a t i o n s can average out, t h i s may be true. In t h i s study, however, no c o r r e l a t i o n between PHA and P was found. Numerous rela t i o n s h i p s were t r i e d such as: 1. anaerobic P release vs. anaerobic PHA storage 2. aerobic P uptake vs aerobic PHA consumption 3. anaerobic PHA storage vs. anoxic+aerobic P consumption 4. t o t a l PHA storage vs. t o t a l P uptake Low R squared c o e f f i c i e n t s (0-0.3) for the above relationships can not be accounted for s o l e l y by factors such as sample va r i a t i o n s , HRT delays and a n a l y t i c a l technique. Therefore, on a day-to-day basis, there i s no c o r r e l a t i o n between PHA and P. Conversely, P release correlated l i n e a r l y with P uptake. R squared c o e f f i c i e n t s were consistently over 0.95 f o r the following r e l a t i o n s h i p s : 1. anaerobic P release vs. aerobic P uptake 2. anaerobic P release vs. anoxic+aerobic P uptake This i s not to say that P release, and not PHA storage, governs the 104 bio-P process performance. I t does say that on a day-to-day basis, the amount of P uptake i s related l i n e a r l y to the amount of P release. I t also suggests that for the most part, release due to H2S or C02 was not very s i g n i f i c a n t i n t h i s study or at le a s t i t s e f f e c t was unchanging. P release did not correlate to e f f l u e n t P or P removal. Manoharan (1988) showed that more P was removed and more P was released when more chemical substrate was added. His study shows that the increased P removal was not due to increased P release, per se. Instead, P release was a by-product of increased chemical substrate addition and as Comeau et a l . (1987) suggested, very l i k e l y the associated increased PHA storage. Another i n t e r e s t i n g point was the shape of the P p r o f i l e i n Figure 4.10c. The more t y p i c a l l y exponentially shaped curve was replaced by a more or less l i n e a r l y shaped curve. This seems to indicate that the P uptake rate was not necessarily dependent on the P concentration. Plots of aerobic P uptake rate vs P concentration i n the i n l e t to the aerobic reactor (such as the o v e r a l l p l o t shown i n Figure 5.3) seem to indicate that, i n general, P uptake rates are higher when the entering P concentrations are higher. However,two points must be considered. F i r s t , the R squared factor was only 0.66. R squared factors for in d i v i d u a l reactors were as low as 0.3. Second, there was a considerable amount of spread, e s p e c i a l l y 105 over the narrow range of P uptake rates and P concentrations encountered i n t h i s study. For example, at an entering P concentration of 5 mg/L, the P uptake rates divided by i n f l u e n t flow rates ranged between 2 and 5 mg/L with the average at about 3.7 mg/L. The range of P concentrations associated with a given P uptake rate was even more variable. At a P uptake rate of 4 mg/L, the associated entering P concentration ranged from 2.5 to 7.5 mg/L, with the average at 5 mg/L. A more l i k e l y explanation of the apparent trend, i s that entering aerobic P concentration was generally higher when entering aerobic PHA concentration was higher. In other words, PHA concentration and P uptake rate may be related. A check of t h i s shows the same kind of loose association as with the other PHA and P correlations attempted. There appeared to be a trend, but the R squared factors were very low. Figures 4.17 and 4.18 are two t y p i c a l P p r o f i l e s during the R2 and PP2 periods respectively. Several differences are noted. F i r s t , the P concentration i n the anaerobic reactor of the experimental module was much lower when p i l o t - p l a n t feed was used than when Richmond feed was used. Second, the P uptake rates i n the aerobic zones d i f f e r e d for the two modules when p i l o t - p l a n t feed was used, whereas they were the same with Richmond feed. The P uptake rates i n the aerobic reactors tapered o f f more rapid l y i n the experimental module than i n the control module. 106 No s i g n i f i c a n t difference i n e f f l u e n t P l e v e l s existed between the two modules a f t e r the anaerobic HRT change when Richmond feed was being used. The consistent difference (of 0 . 5 - 1 . 0 mg/L), which persisted for the remainder of the experiment, started shortly a f t e r the switch to p i l o t - p l a n t feed. Therefore the design effectiveness of the anaerobic zone HRT appears to be a function of the c h a r a c t e r i s t i c s of the feed sewage. In a related issue, when there was net anoxic P release taking place, the experimental module always showed more release than the control module. Differences i n anoxic zone P releases were t y p i c a l l y about 3-5 mg/L. A comparison of anaerobic zone VFA l e v e l s i n Figure 5.1 shows that, a f t e r the anaerobic zone HRT i n the experimental module was reduced, more VFA's were detected and also more frequently i n that module. I t seems then that the capacity to assimilate VFA's was exceeded i n the shorter anaerobic HRT module. Assimilation i n the subsequent anoxic zone, while contributing to P removal, did not seem to be as e f f e c t i v e as when more of the VFA's were assimilated i n the anaerobic zone. In short, the reduced anaerobic HRT was too short under the given i n f l u e n t and operational conditions. Increased VFA's i n the feed sewage led to excess VFA's i n both modules. In fact, VFA detection i n the feed (Figure 4.23) always led to VFA detection i n the completely mixed anaerobic zone of the experimental module (Figure 5.1). I t also often led to detection i n the anaerobic zone of the control module. The measured feed peaks of up to 10 mg/L led to anaerobic peaks of about 2 and 4 mg/L i n the control and experimental modules, respectively. In most cases, these VFA peaks i n the feed also corresponded to higher anaerobic P release which, as mentioned e a r l i e r , also corresponded to lower ef f l u e n t P l e v e l s . This i s well documented i n the l i t e r a t u r e by Comeau (1984), Rabinowitz (1985) etc. Other parameters used to assess carbon content were reviewed to see i f they also were high when ef f l u e n t P was low. Higher BOD5, COD and TOC values occasionally were related to lower e f f l u e n t P l e v e l s . Lower values were related to higher e f f l u e n t P l e v e l s . On many occasions however, t h i s r u l e did not hold, e s p e c i a l l y f o r t o t a l u n f i l t e r e d COD and for f i l t e r e d TOC. In the case of BOD5 and TOC, sampling was too infrequent to draw firm conclusions. In a l l cases, i t can be said that the actual value was not as important as the r e l a t i v e change i n values within the cont r o l l e d range of in f l u e n t conditions i n t h i s experiment. S t i l l , v a r i a t i o n i n in f l u e n t VFA was the best explanation f o r P removal behaviour. I m p l i c i t i n these r e s u l t s i s the importance of the location of VFA consumption. With both modules being subjected to the same conditions, at lea s t some of the difference i n P removal c a p a b i l i t i e s has to be attributed to the fac t that a shortened anaerobic HRT gave r i s e to lower assi m i l a t i o n of VFA's i n that 108 zone. Gerber et a l . (1987) also made the point that, while increased VFA's led to higher P removal, VFA carry-over to the anoxic zone was counter productive. This i s not to say that other factors, perhaps induced by the anaerobic HRT reduction, did not also have an impact on P removal. A presentation of the PHA data was held back to the end because, for the most part, i t did l i t t l e to c l a r i f y the descriptions i n the previous sections. On occasion, PHA varied by as much as 50% from sample to sample, at times when e f f l u e n t P was steady. Conversely, occasionally PHA was steady when ef f l u e n t P was varying. I f the measured PHA concentrations are accurate, then the v a r i a t i o n s i n PHA are a r e f l e c t i o n of the v a r i a t i o n s i n the feed sewage strength and c h a r a c t e r i s t i c s . The trends evident i n Figure 5.4 seem to indicate that the measured PHA concentrations are generally accurate. Reduced PHA consumption towards the end of the experiment are i n l i n e with observed reductions i n P removal. S p e c i f i c PHA measurements however, could be i n error because of problems and v a r i a b i l i t y , e i t h e r i n the sampling or i n the analysis. Figure 5.4 shows the PHA mass flow rate through each of the zones. There i s no evidence to explain the difference between P removal i n the control module with Richmond feed and with p i l o t - plant feed. With the exception of the l a s t two months of data, there i s also no evidence to explain the difference i n P removal between the two modules a f t e r the anaerobic HRT change. O -15 - I — i — i — i — i — i — i — i — i — ° \ — i — i — i — i — i — i — i — i — i — i — J 0 2 4 6 8 10 12 14 16 18 20 PHOSPHATE CONCENTRATION as P IN CELL INLET (mg/L) Figure 5.3 PHOSPHATE MASS UPTAKE RATE as P vs INLET PHOSPHATE CONCENTRAT ION as P - BOTH MODULES. 40 -r 5 o _i 35 - u. t- z UJ 30 - 3 _1 LL E. 25 - z CD LU O X CL 20 - tn A o < 15 -i- X to Cu CO CO 10 - < 5 5 - < X Cu 0 - AN HRT CHANGE t t PILOT-PLANT FEED CHANGE a CONTROL * EXPERIMENTAL 40 80 120 160 200 CUMULATIVE TIME (DAYS) 240 280 a. ANAEROBIC ZONE PHA STORAGE 5 o ui * CUMULATIVE TIME (DAYS) X °- b. ANOXIC ZONE PHA STORAGE OR CONSUMPTION Figure 5.4 P H A Mass Storage or Consumpt ion in the Anaerobic, Anoxic and Aerobic Zones . The lack of relat i o n s h i p between PHA and ef f l u e n t P or process P removal may indicate that' the PHA stored i n one cycle may not be completely consumed i n that cycle. I n s u f f i c i e n t DO might have t h i s e f f e c t , although care was taken to reduce the p o s s i b i l i t y of t h i s happening. Non-steady-state conditions such as changes i n feed sewage c h a r a c t e r i s t i c s , flow rate, plugging etc. could also r e s u l t i n incomplete PHA removal i n a given cycle. Varying, disproportionate PHA storage between bio-P organisms would also have t h i s e f f e c t . Furthermore, with the anoxic-anaerobic recycle, there i s no true cycle. On occasions then, some build-up may take place while on others, some increased consumption may take place. The long term tendency would be towards a balance between storage and consumption. In the short term however, some s p e c i f i c conditions may a r i s e which regulate the actual amount of PHA storage or consumption taking place. In general, PHA consumption and P accumulation during the batch t e s t s (Figure 4.25) occurred at nearly the same rate. The o v e r a l l trends for PHA consumption and P accumulation were also the same i n the anoxic and the aerobic zones during continuous flow t e s t i n g (Figures 5.5 and 5.6). This was e s p e c i a l l y noticeable i n extreme cases, where high or low P uptake and low or high PHA consumption were noted respectively. Anaerobic PHA storage and P release show quite d i f f e r e n t trends however, as seen i n Figure 5.7. This was p a r t i c u l a r l y true when the anaerobic HRT of the experimental module was < Q ci I OC CO O Z UJ O o o O ° CO to CO S CO 1J < UJ 5 DC < co CL < UJ o o I - CO < I CL 3 co z o o < X Q- UJ CO < UJ _J UJ cc CL UJ < y- CL CL 30 25 20 15 10 -10 : A , • PHA - P04-P MLS A V. i i i i i i i i i i ~ 1 1 1 40 80 120 160 200 CUMULATIVE TIME (DAYS) 240 280 a. EXPERIMENTAL MODULE cn £ O l - CL s 3 CO z o o OC o UJ o O t- co CO CO < 2 < I 0. cn £ . UJ < i- CL 3 CC O UJ CO < Ul - J UJ cc CO CO < CL UJ O £ O h- co < X CL z o h- CL 2 3 CO z o o < X CL CO < UJ —I UJ cc CL UJ CL 3 CL 30 25 20 15 - 10 5 - -10 40 80 120 160 200 CUMULATIVE TIME (DAYS) 240 .280 b. CONTROL MODULE Figure 5.5 Anoxic Zone P H A Storage or Consumpt ion and Phosphate Release or Uptake CUMULATIVE TIME (DAYS) b. CONTROL MODULE Figure 5.6 Aerobic Zone PHA Mass Consumption and Phosphate Mass Uptake as P Figure 5.7 Anaerobic Zone P H A Storage and P Release 115 reduced. P release and P removal followed s i m i l a r trends; PHA storage followed a d i f f e r e n t trend. I t appears that more PHA storage i n the anaerobic zone does not necessarily lead to more P removal for that cycle or that day. Sustained increases may have a d i f f e r e n t e f f e c t , as data from Manoharan 1s (1988) work indicates. Although the anaerobic HRT i n the experimental module was probably too short, a f t e r the anaerobic volume change, the amount of PHA storage remained r e l a t i v e l y unchanged, as seen i n Figure 5.4. At the same time, the amount of anaerobic P release dropped by 20 to 40 % of the pre-change l e v e l s (Figure 4.3). This i s an i n d i c a t i o n that the o r i g i n a l anaerobic HRT was too long, thus giving r i s e to some P release without the associated PHA storage. Even so, i t seems that an anaerobic zone which i s too long may be preferable to one which i s too short. S t i l l , an optimum anaerobic HRT may l i e between the two values tested here. Anaerobic PHA storage was about the same i n both modules before and a f t e r the anaerobic HRT reduction i n the experimental module. Anaerobic P release was also very s i m i l a r i n both modules p r i o r to the anaerobic HRT reduction. A f t e r the HRT reduction, however, c l e a r l y less P was released i n the anaerobic zone of the experimental module (Figure 4.3) than i n the control module. In other words, less P was released i n the experimental module a f t e r the anaerobic HRT reduction, but e s s e n t i a l l y the same amount of PHA was s t i l l stored. This implies that most of 116 the additional P release i n the control module was not associated with PHA storage. Not a l l of t h i s additional P release i n the anaerobic zone of the control module (over and above that i n the experimental module) was necessarily of the secondary type. When VFA's were detected i n the feed, the larger anaerobic volume of the control module had extra capacity. Consequently, VFA's did not carry- over to the anoxic zone of the control module as often as i n the experimental module. Therefore, some P release must have been as a r e s u l t of VFA assimilation and PHA storage. 5.3. E f f e c t of Anoxic HRT Optimum s i z i n g of the anoxic zone i n the UCT process i s dependent on the NOx loading to that zone and the o v e r a l l average d e n i t r i f i c a t i o n rate. The NOx load depends on the TKN or NH3 content of the i n f l u e n t , the degree of n i t r i f i c a t i o n and the t o t a l recycle rate of a l l streams recycled back to the anoxic zone. The d e n i t r i f i c a t i o n rate i s affected by the carbon c h a r a c t e r i s t i c s of the feed, the temperature and a host of other factors which may have an impact. Examples of other factors are microbial make-up, the amount of anaerobic carbon storage taking place, the amount of aerobic oxidation taking place and the amount of DO recycled to the anoxic zone. Due to the number of variables, i t i s not possible to design an optimum sized reactor under a l l conditions, e s p e c i a l l y given the p o t e n t i a l for 117 v a r i a b i l i t y i n parameters such as t o t a l carbon content and c h a r a c t e r i s t i c s thereof. Rabinowitz (1985), Comeau (1984) and many others have demonstrated the detrimental e f f e c t s on P removal of NOx recycled to the anaerobic zone. Clearly then, to err on the conservative side and design for some excess d e n i t r i f i c a t i o n capacity i s j u s t i f i a b l e . One finding of t h i s study i s that excess d e n i t r i f i c a t i o n capacity may be detrimental to P removal. Hence i t may be b e n e f i c i a l f o r designers to eithe r spend more e f f o r t on determining the r e a l anoxic zone requirements or to b u i l d i n f l e x i b i l i t y and sel e c t a control strategy to compensate for v a r i a b i l i t y i n the mass of NOx recycled to the anoxic zone. The former p o s s i b i l i t y , as mentioned before, can only provide a range of capacity and at best would be associated with considerable uncertainty. Influent carbon content could vary d i u r n a l l y and with the day of the week. Carbon c h a r a c t e r i s t i c s (such as biodegradability) could vary with flow rate and temperature. D e n i t r i f i c a t i o n - r a t e varies with temperature, carbon content and c h a r a c t e r i s t i c s . Given the indeterminate v a r i a b i l i t y of these factors, the only p r a c t i c a l way of proceeding i s to vary the loading rate (ie NOx recycle rate) so that the in-place capacity — i t s e l f a variable — i s f u l l y u t i l i z e d but also not exceeded. 118 Although no control strategy was evaluated as part of t h i s study, ORP appears to be a suitable t o o l for optimizing the d e n i t r i f i c a t i o n period i n SBR's. (Koch and Oldham (1986), Koch et a l . (1988) and Peddie et a l . (1988)). Therefore, i t i s l i k e l y that a p r a c t i c a l control strategy could be developed which would have the p o t e n t i a l for reducing e f f l u e n t P peaks by as much as 1 or 2 mg/L, for a wastewater with c h a r a c t e r i s t i c s l i k e those found i n t h i s study. Due to the p o s s i b i l i t y of r e c y c l i n g DO back to the anoxic zone, the c l a r i f i e r underflow recycle rate would be the best source of varying the NOx load. Internal recycle could be used as a f i n e tuning supplement. In e i t h e r case, maintaining a r e l a t i v e l y low DO towards the end of the aerobic zone (for plug flow) could also help. This could, however, impact negatively, on aerobic zone P uptake performance. I f nitrogen removal i s also important, a modified UCT process shown i n Figure 5.8 would probably be the best choice. In t h i s case, the second anoxic zone should be overloaded (ie the NOx concentration should be greater than zero) and the f i r s t anoxic zone should be operated as described previously. PRIMARY SECONDARY ANAEROBIC ANOXIC ANOXIC AEROBIC REACTOR REACTOR REACTOR REACTOR MIXED LIQUOR RECYCLES SLUDGE RECYCLE Figure 5 .8 Modified UCT Process 120 5.4. E f f e c t of Anaerobic HRT The i n i t i a l s e l e c t i o n of experimental HRT values to investigate was based, i n error, on the chemical substrate load only. From Rabinowitz (1985), the VFA consumption rate i n the anaerobic zone was estimated to be about 0.5 mg/L/min/g MLSS. Therefore, a VFA addition of 15 mg/L should require about 15 minutes of actual HRT for complete consumption. But the portion of the raw sewage organic carbon which may also contribute to the enhanced b i o l o g i c a l phosphorus removal process i n a s i m i l a r way to added VFA's was not considered. Manoharan (1988) has shown that the sewage used both i n h i s work and i n t h i s study t y p i c a l l y would contain about 20-25% r e a d i l y biodegradable (RBD) f r a c t i o n , on a COD basis. For an average i n f l u e n t COD of 200-230 mg/L, t h i s amounted to 20 to 30 mg/L RBD as COD. Supplemented by 15 mg/L acetate/propionate as COD, the t o t a l RBD f r a c t i o n plus VFA was about 35-45 mg/L as COD. This amount would require about 35-45 minutes of actual anaerobic HRT to f u l l y consume the VFA's i n the feed plus chemical substrate . Furthermore, the RBD f r a c t i o n may require more time f o r uptake than an equivalent amount of VFA on a COD basis because of p o t e n t i a l l y more complex mixtures. Consequently, the choice of 40 minutes f o r the anaerobic HRT was too short. The experimental value of 40 minutes was obviously close to the predicted s i z e but very l i k e l y j u s t a l i t t l e small, as the t e s t r e s u l t s proved. Feed containing peaks of an extra 10 mg VFA/L or more would require an additional 10 minutes. An i d e a l s i z e 121 might be close to 50-60 minutes for the feed conditions i n t h i s study, as evidenced by the measured concentration of VFA's i n the anaerobic zone of the experimental module. The o r i g i n a l actual anaerobic HRT of 80 minutes i s very l i k e l y too long based on two observations. F i r s t , a 50% reduction i n anaerobic HRT only led to a 20-40% reduction i n P release, suggesting that some secondary P release was taking place. Comeau (1984) and Rabinowitz (1985) both show t h i s same pattern of P release under anaerobic conditions, i n Figures 2.6 and 2.7. Second, the same reduction only reduced the amount of PHA stored by 10-20% and that was only towards the end of the experiment. Furthermore, Manoharan (1988) had added 25 mg/L of acetate to the same sized process with the same feed conditions and never observed VFA's i n the anaerobic zone. This seems to indicate that the anaerobic zone was at l e a s t large enough for complete VFA consumption. I t seems l o g i c a l to assume that adding le s s VFA substrate would require less HRT for complete VFA consumption. Therefore, a reduction i n VFA addition from 25 mg/L to the 15 mg/L l e v e l used here would leave the anaerobic zone somewhat oversized. An event i n Manoharan's research shows that t h i s s i t u a t i o n i s l i k e l y . During one phase of Manoharan's research, an anomaly i n the i n f l u e n t sewage conditions resulted i n a 10 mg/L as COD increase i n VFA concentration over a previous run. Even so, t h i s did not r e s u l t i n VFA detection i n the anaerobic zone. 122 Therefore, the anaerobic zone was s t i l l large enough to allow fo r complete VFA consumption, even a f t e r a step increase i n VFA addition. One other factor associated with a reduction i n the anaerobic HRT i s the e f f e c t that i t would have on the se l e c t i o n of bio-P organisms. A reduced anaerobic HRT, as i n t h i s experiment, was also associated with a reduction i n anaerobic mass f r a c t i o n . In t h i s case i t amounted to a drop from 8-9% of the t o t a l mass i n the control module to about 6% i n the experimental module. With the exception of some fermentative anaerobes which might be able to survive the aerobic zone, the bio-P organisms are e s s e n t i a l l y the only organisms to benefit from the anaerobic conditions; hence t h e i r p r o l i f e r a t i o n . By reducing the anaerobic HRT, we may be reducing the competitive advantage that bio-P organisms have, by reducing t h e i r opportunity to store carbon ( i f the HRT was reduced too much as in t h i s case). We would also simultaneously be increasing the opportunity of other bacteria to survive the anaerobic zone and to survive i t i n better condition. Moreover, we may also be allowing the other organisms an opportunity of consuming some of the so-called desirable forms of carbon, as i t bleeds through into the anoxic zone. Bio-P type organisms apparently have a competitive edge over other non-bio-P organisms, e s p e c i a l l y heterotrophs. This i s because of t h e i r a b i l i t y to assimilate the more degradable 123 carbonaceous material i n the feed while i n the i n i t i a l anaerobic zone; something non-bio-P organisms can not do. Non-bio-P organisms not only must survive the period of anaerobiosis each cycle, but they must also grow on the remaining l e s s biodegradable material under aerobic conditions. Under P l i m i t i n g conditions, bio-P organisms may also have an additional advantage; they can grow using t h e i r P reserves. The MLSS concentration i n the experimental module increased and remained higher a f t e r reducing the anaerobic HRT of that module. Pr i o r to changing the anaerobic volume of the experimental module, both modules had the same MLSS concentrations. Furthermore, the MLSS of both modules was combined and re-apportioned to the two modules p r i o r to t e s t i n g of the shortened anaerobic HRT. This ensured that both modules would s t a r t with the same mix of organisms. The mass loading of COD i n both the feed and i n the added chemicals was the same for both modules. The difference i n MLSS might be the r e s u l t of increased growth of non-bio-P organisms. The non-bio-P organisms not only were passing through a reduced period of anaerobiosis i n the experimental module, but they were also exposed to more r e a d i l y biodegradable material than before the anaerobic HRT reduction. The increased growth of the non-bio-P organisms appeared to be at the expense of the bio-P organisms. The mixing of the sludges from both modules at the end of the experiment c l e a r l y 124 showed a difference i n the bio make-up of the two modules. The r o l e that the anaerobic mass f r a c t i o n played i n the se l e c t i o n of microorganisms i s not known. When the anaerobic HRT of the experimental module was cut i n ha l f , the anaerobic MLSS concentration increased, but i t did not double. Consequently, the mass of MLSS i n the anaerobic zone was less i n the experimental module. Since the mass i n the other zones remained e s s e n t i a l l y unchanged, the anaerobic mass f r a c t i o n was also reduced with the HRT. Therefore, the observed changes between the two modules could also be p a r t l y a t t r i b u t e d to the differences i n the anaerobic mass fr a c t i o n s . An increased anaerobic mass f r a c t i o n means that non-bio-P organisms are subjected to longer periods of anaerobiosis. This might give bio-P organisms a greater edge over other organisms which can not take advantage of anaerobic conditions. Reducing the anaerobic mass f r a c t i o n would l o g i c a l l y cut the advantage that bio-P organisms have over non-bio-P organisms. In order to maintain a s i m i l a r anaerobic mass f r a c t i o n or to increase the mass f r a c t i o n , an appropriate aerobic and/or anoxic HRT reduction could be undertaken simultaneously with an anaerobic HRT reduction. The impact of the anoxic zone HRT reduction has already been discussed and there i s a l i m i t as to how much the HRT could be reduced before n i t r a t e would carry-over into the anaerobic zone. Therefore, an aerobic zone HRT reduction might be required i n order to keep the anaerobic mass f r a c t i o n from becoming too small. The p o s s i b i l i t y of reducing the aerobic HRT 125 w i l l be discussed i n the following section. 5.5. E f f e c t of Aerobic HRT We have seen that the optimum anaerobic HRT probably l i e s somewhere between the two HRT's tested here; the o r i g i n a l being too long, the experimental, too short. The aerobic zone was purposely divided into 4 sequential c e l l s so that some aspects of the impact of HRT on P removal performance could be evaluated. These aspects include P uptake rate, metabolization of substrate, microbial make-up and over oxidation. Early i n the study, P p r o f i l e s such as the one i n Figure 4.10 for July 27 (t=31 days) showed the aerobic zone to be more than double the s i z e necessary to reduce P l e v e l s to below 0.5 mg/L. The biomass was increasing at t h i s point due to an increase i n feed strength. By the time steady state loading was reached, the aerobic P uptake rate had dropped by 30-40%. From t h i s point on, a l l aerobic c e l l s appeared necessary to achieve e f f i c i e n t P removal. The P p r o f i l e s , showing the P uptake rates, varied between the two extreme cases shown i n Figure 4.10 (October 8th and 12th). P r o f i l e s taken a f t e r steady state MLSS concentration was achieved showed that P was being removed from solu t i o n i n a l l aerobic c e l l s . Therefore, under t e s t loading conditions, any reduction i n aerobic HRT would be expected to have a negative 126 impact on e f f l u e n t P concentration and on calculated P removal. Other evidence, however, suggests that t h i s would not necessarily be the case. F i r s t , i t i s noted that ammonia was completely u t i l i z e d a f t e r the second aerobic reactor. N i t r i f i c a t i o n was also complete a f t e r the second reactor i n most cases. Soluble COD and TOC have varied considerably within the aerobic zone, but no further reduction was noted a f t e r the f i r s t aerobic reactor. Jones et a l . (1986) reported almost i d e n t i c a l findings. Only one BOD t e s t could be conducted due to the sample volumes necessary. Soluble BOD5 was measured on March 25th, 3 days a f t e r the sludges were mixed. The p r o f i l e i n Figure 5.9 shows that e s s e n t i a l l y no change i n soluble BOD took place a f t e r the second aerobic reactor. The feed value i n Figure 5.9 does not take into account the chemical substrate addition. Therefore, by f a r the largest amount of soluble BOD was taken up i n the anaerobic zone. Oxygen uptake rates measured i n September and October, p r i o r to the anaerobic HRT change, with Richmond feed, showed the f i r s t aerobic reactors to be more active than the rest.OUR's were t y p i c a l l y i n the range of 30-40 mg/L/h i n the f i r s t aerobic reactor and about 15 mg/L/h i n subsequent aerobic reactors. This trend was also seen i n the aeration rate required to keep the DO l e v e l s at 2 mg/L. The l a s t two reactors required very l i t t l e 127 Figure 5.9 So lub le Biochemical Oxygen Demand Profile 128 a i r compared to the f i r s t two. Bubble s i z e was about the same i n a l l reactors. Mixers were required i n the l a s t two reactors to keep s o l i d s i n suspension. Throughout most of the study, a f t e r steady state MLSS was achieved, the l a s t aerobic c e l l accounted for 10% or less of the t o t a l aerobic zone P uptake. The l a s t two reactors accounted for about 25% of t h i s t o t a l . By comparison, the f i r s t aerobic c e l l accounted for about 40-50% of the t o t a l aerobic zone P uptake. PHA followed a s i m i l a r trend with more PHA consumed i n the f i r s t c e l l and less i n subsequent c e l l s . Again, le s s than 10% was consumed i n the l a s t aerobic c e l l . I t seems that most of the ammonia u t i l i z a t i o n , carbon oxidation and n i t r i f i c a t i o n takes place i n the f i r s t two aerobic c e l l s . Only P uptake was found to require the remaining 50% of the aerobic HRT. A reduction i n aerobic HRT by 50% could change the microbial make-up of the biomass. The anaerobic mass f r a c t i o n would increase from less than 10% to about 15%. Whether or not t h i s would give the bio-P organisms an increased advantage i s not known but Gerber and Winter (1984) studied the e f f e c t of anaerobic HRT's up to 24 hours and anaerobic mass fra c t i o n s over 40% and found no i l l e f f e c t s on P removal or e f f l u e n t P l e v e l s . 129 Using data from October 8th as a representative example, a 50% reduction i n aerobic HRT would change the e f f l u e n t P l e v e l from 0.2 to 3.0 mg/L immediately. The c l a r i f i e r underflow would then contain about 15-25% more PHA than previously. Assuming that new PHA storage i n the anaerobic zone remains constant, the sludge returning to the aerobic zone should contain more PHA reserves. The aerobic P uptake rate should increase by a corresponding amount. The P l e v e l i n the anaerobic and anoxic zones would also increase, since the c l a r i f i e r underflow P concentration has increased from 0.2 to 3.0 mg/L. The anoxic zone P l e v e l would increase by 1 mg/L based on hydraulic flowrates. So the P uptake rate would have to increase by more than 1 mg/L, to e f f e c t an improvement in o v e r a l l P removal. I t i s possible that part of the reason for net P uptake rates tapering o f f i n the aerobic zone i s the re-release of some P due to over-oxidation. Stevens and Oldham (1987) reduced the DO l e v e l to reduce excessive oxidation i n a Phoredox process. They found that P removal improved as a r e s u l t of t h i s operating strategy. Therefore, the aerobic zone has good p o t e n t i a l for optimization through HRT reduction. This must be shown experimentally since an aerobic HRT reduction would a f f e c t the microbial make up of the biomass due to s e l e c t i v i t y 130 considerations. I t would also a f f e c t the condition of the biomass as i t i s recycled to the anoxic zone. 5.6. Comparison with Others This project was planned so that r e s u l t s could be compared d i r e c t l y to those of Manoharan (1988). In order to do t h i s , a l l physical and operating parameters were matched as c l o s e l y as possible. Two' intentional differences were the aerobic zone configuration and the chemical substrate composition. Four,one- l i t r e , complete-mix reactors i n series, simulating plug flow, were used here to allow for an evaluation of the aerobic zone capacity. A combination of acetate and propionate was selected as being more representative of the make-up of the feed to the bio-reactor of a f u l l - s c a l e treatment plant that u t i l i z e s primary sludge fermentation for VFA production. On the other hand, Manoharan used o n e , f o u r - l i t r e , complete-mix reactor f o r the aerobic zone and studied the e f f e c t s of s i n g l e chemical additions. The dissolved oxygen l e v e l was c o n t r o l l e d between 1 and 2 mg/L i n Manoharan's experiment while the DO l e v e l varied between 1 and 3 mg/L here. As mentioned e a r l i e r , with the exception of the extreme values, DO was not a factor i n o v e r a l l P removal although i t may have affected P uptake i n i n d i v i d u a l reactors. One unintentional difference between the two experiments was the feed. Manoharan was able to control the feed composition within close tolerances not achieved i n t h i s experiment. The primary difference was i n feed COD which Manoharan kept to within 10 % of 250 mg/L (including chemical addition). Extreme peaks were not common i n Manoharan 1s work, whereas v a r i a b i l i t y was more the norm i n t h i s work. Note that Manoharan only monitored COD twice weekly, compared to the d a i l y sampling schedule here. The actual target average COD of 250 mg/L was met i n t h i s study, but the v a r i a t i o n was more l i k e 15-20 %. The extent of the v a r i a t i o n however, may not have been as important as the nature of the v a r i a t i o n , which i n t h i s project, tended to be c y c l i c . The broad mix of activated sludge organisms, each with d i f f e r e n t metabolic rates may maintain some degree of consistency under random v a r i a t i o n s . The 2-3 week cycles, where feed COD decreased ste a d i l y , only to jump back up when fresh sewage was co l l e c t e d , may have exceeded the storage capacity, thus r e s u l t i n g i n non-steady state behaviour. Manoharan was able to do f i v e runs of varied chemical substrate concentrations within 6 or 7 months because steady state was achieved within 2 weeks or less and was maintained for 3 weeks or more. The difference between the r e s u l t s of t h i s experiment and of Manoharan 1s i l l u s t r a t e s two main points. F i r s t , the Richmond feed was d i f f e r e n t than the p i l o t - p l a n t feed, even when d i l u t e d to s i m i l a r COD values. A comparison of the e f f l u e n t 132 c h a r a c t e r i s t i c s i n t h i s experiment also confirms t h i s conclusion. Second, even with p i l o t - p l a n t feed, differences existed between the two projects. Manoharan found that, for the same concentration of chemical substrate addition measured as COD, acetate was more e f f e c t i v e i n enhancing P removal than propionate. A 50:50 mixture of acetate and propionate might be expected to r e s u l t i n an average of the single chemical enhancements. E f f l u e n t P l e v e l s for t h i s experiment might then be expected to be i n the range of 1-1.2 mg/L based on Manoharan's other values. Instead, with the Richmond feed, e f f l u e n t P l e v e l s were about 0.2-0.4 mg/L. Average P removal i n the control module, using Richmond sewage as feed was 3.6 mg/L compared to 3.5 mg/L with acetate and 2.5 mg/L with propionate as substrates i n Manoharan's research. Two other factors may help explain the differences noted here. F i r s t , VSS l e v e l s were higher using Richmond feed. Perhaps the difference i n P removal could be p a r t l y a t t r i b u t e d to more growth. This would imply more biodegradable COD i n the Richmond feed. The BOD5/COD r a t i o for Richmond sewage was about 0.48 vs about 0.35 for p i l o t - p l a n t sewage, lending credence to t h i s p o s s i b i l i t y . The very low r a t i o could be due to the very "fresh" nature of the sewage. Table 5.1 shows these u n f i l t e r e d B0D5/C0D r a t i o s for both P i l o t - p l a n t and Richmond sewages. 133 Table 5.1 Ratio of B0D5 to COD for Richmond and P i l o t - P l a n t Sewages DATE CUMULATIVE DAY BOD5 UNFILTERED (mg/L) COD UNFILTERED (mg/L) BOD5/ COD RICHMOND SEWAGE 87-09-30 96 112 385 0.29 87-10-07 103 114 275 0.41 87-10-14 110 114 256 0.45 87-10-21 117 120 239 0. 50 87-10-28 124 114 217 0. 53 87-11-04 131 128 250 0.51 87-11-10 137 112 204 0. 55 87-11-16 143 119 197 0.60 87-11-25 152 105 280 0.38 87-12-04 161 131 209 0.63 87-12-10 167 110 253 0.43 RICHMOND SEWAGE AVERAGE RATIO = 0.48 PILOT-PLANT SEWAGE 87-12-28 185 101 236 0.43 87-12-31 188 77 213 0.36 88-01-07 195 68 204 0.33 88-01-18 206 60 213 .0.28 88-01-25 213 45 245 0. 18 88-01-30 218 83 202 0.41 88-02-08 227 69 189 0. 37 88-02-12 231 70 177 0.40 88-02-15 234 47 160 0.29 88-02-19 238 82 222 0.37 88-02-22 241 90 220 0.41 88-02-26 245 65 191 0.34 88-02-29 248 61 208 0. 29 88-03-04 252 64 196 0.33 88-03-07 255 45 163 0.28 88-03-08 256 89 218 0.41 88-03-15 263 98 213 0.46 88-03-17 265 79 214 0. 37 88-03-22 270 70 210 0.33 88-03-25 273 80 195 0.41 PILOT-PLANT SEWAGE AVERAGE RATIO = 0.3 5 134 I t i s understandable that a stronger feed could r e s u l t i n better P removal. When the feed was weaker during the PP2 period, P removal was s l i g h t l y less than reported by Manoharan, under s i m i l a r chemical substrate additions. In a l l cases, the Richmond and p i l o t - p l a n t feed had about the same f r a c t i o n of re a d i l y biodegradable material according to Manoharan, so that COD could be correlated to P removal. The other factor was the TKN load difference, which resulted i n a higher NOx load to the anoxic zone i n Manoharan's experiment. On the one hand, t h i s may have served to improve the o v e r a l l P removal by u t i l i z i n g more of the anoxic d e n i t r i f i c a t i o n capacity, thereby l i m i t i n g the amount of secondary release i n the anoxic zone. Gerber et a l . (1987) showed that P i s released a f t e r d e n i t r i f i c a t i o n i s complete i n the anoxic zone. On the other hand, more P was being taken up i n the anoxic zone i n Manoharan's work. I f the t h e o r e t i c a l considerations reported by Comeau et a l . (1987) are correct, i n d i c a t i n g that less energy i s produced when NOx i s used as the electron acceptor, then the o v e r a l l P removal c a p a b i l i t y would be decreased i n Manoharan's process. This i s true for the case when PHA i s l i m i t i n g . When PHA i s not l i m i t i n g , the P uptake i n the anoxic zone would obviously reduce the aerobic volume required for complete P uptake. 135 Since one p o s s i b i l i t y tends to cancel out the impact of the other, the net impact on P removal, due to the differences i n observed TKN, load would probably be small. The main difference that impacted on P removal was therefore the feed COD or BOD strength. The feed BOD strength was also the main difference between Richmond feed and p i l o t - p l a n t feed i n t h i s experiment. Average COD had also dropped by nearly 20% when changing from Richmond to P i l o t - p l a n t sewage, but BOD5 had dropped by 30-50%. Comparing Manoharan's r e s u l t s to the r e s u l t s obtained here using p i l o t - p l a n t feed, below, we see that average P removal values f o r the control module tended to l i e somewhere between the values Manoharan reported for acetate and propionate. Manoharan Lee Acetate Propionate Acetate/Propionate P removal 3.5 2.5 3.0 (mg/L) The only difference was the lower COD i n t h i s experiment. This reduction i n COD may have accounted for the reduction i n P removal. I t seems then, that two s i m i l a r bio-P type processes, such as the UCT types investigated here and by Manoharan, can be expected to achieve s i m i l a r r e s u l t s i f the feed conditions are also s i m i l a r . Increasing the organic feed strength w i l l then tend to improve the P removal c a p a b i l i t y . 136 Chapter 6. Conclusions 1. Under the in f l u e n t sewage and chemical substrate addition conditions of t h i s experiment, the reduced anaerobic HRT system removed less phosphate and discharged e f f l u e n t at a higher phosphate l e v e l than the o r i g i n a l anaerobic HRT system. 2. The difference i n microbial make-up under the d i f f e r e n t anaerobic HRT conditions was at l e a s t i n part a contributing factor to the difference i n phosphate removal c a p a b i l i t i e s between the two systems. 3. The VFA carry over from the anaerobic zone to the anoxic zone i n the experimental module a f t e r the anaerobic HRT change was a contributing factor to the difference i n phosphate removal c a p a b i l i t i e s of the two systems. 4. I t i s possible that the o r i g i n a l anaerobic HRT was longer than the optimum, since a 50% reduction i n anaerobic HRT did not lead to a 50% reduction i n PHA storage. 5. Within the range of anaerobic HRT's studied, exceeding the optimum was apparently more desirable than having an i n s u f f i c i e n t HRT, with respect to phosphate removal and e f f l u e n t phosphate l e v e l s . 6. Influent organic sewage strength had an impact on the 137 d e n i t r i f i c a t i o n rate and hence the anoxic HRT requirements for complete d e n i t r i f i c a t i o n . 7. Since the inf l u e n t organic sewage strength i s t y p i c a l l y a v a r i a b l e parameter, an optimum anoxic HRT can not be set for a l l i n f l u e n t conditions. 8. Some means of varying the actual anoxic HRT such that d e n i t r i f i c a t i o n i s always complete, and only j u s t complete, would probably improve the phosphate removal c a p a b i l i t i e s of any given bio-P process. 9. Nearly 50% of the t o t a l aerobic phosphate uptake occurred i n the f i r s t 25% of the aerobic HRT. Furthermore, only 10% of the t o t a l aerobic phosphate uptake occurs i n the l a s t 25% of the aerobic HRT. Hence there i s a p o s s i b i l i t y that the aerobic HRT could be reduced by 25% or more without a s i g n i f i c a n t impact on o v e r a l l P removal. 10. About 10-25% of the t o t a l phosphate uptake occurred i n the anoxic zone during t h i s study. Since phosphate uptake i s more e f f i c i e n t per unit of PHA consumed when 0 2 i s used as the electron acceptor rather than NOx, phosphate removal, under PHA l i m i t i n g conditions may be improved by reducing t h i s percentage. Conversely, under excess PHA conditions, increased P uptake i n the anoxic zone has the pote n t i a l for reducing the aerobic HRT required f o r complete P removal. 138 Chapter 7. Recommendations 1. Given that n i t r i f i c a t i o n , ammonia oxidation and soluble COD or BOD oxidation are a l l e s s e n t i a l l y complete within the f i r s t 50% or les s of the aerobic HRT, the bio-P process should be tested at 50% of the aerobic HRT with the o r i g i n a l anaerobic HRT to determine the steady state e f f e c t on phosphate removal. 2. The bio-P process studied i n t h i s experiment should be tested at an anaerobic HRT of about 60 minutes (approximately h a l f way between the o r i g i n a l and reduced anaerobic HRT's studied here). 3. Use ORP measurement and recycle rate manipulation to optimize the anoxic HRT on a r e a l time basis. 4. A serie s of te s t s should be conducted to determine whether the actual anaerobic HRT or the anaerobic mass f r a c t i o n i s more important to provide a competitive advantage to bio-P organisms. 139 Chapter 8. References Alarcon, G. O. (1960). 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"Phosphorus release and uptake i n enhanced b i o l o g i c a l phosphorus removal from wastewater.", Proc. 8th Symp. on Wastewater Treatment, Montreal, Quebec, 301-323, to be publ. i n J . Water Po l l u t . Control Fed. Comeau, Y.; Oldham, W. K. and H a l l , K. J . (1987). "Dynamics of carbon reserves i n b i o l o g i c a l dephosphatation of wastewater.", Pres. at IAWPRC i n t . Conf. on B i o l o g i c a l Phosphate Removal from Wastewaters, Rome, I t a l y , Sept. 28-30, 1987. Daigger, G. T.; Randall, C. W.; Waltrip, G. D; Romm, E. D. and Morales, L. M. (1987). "Factors a f f e c t i n g b i o l o g i c a l phosphorus removal for the VIP process, a high rate u n i v e r s i t y of Capetown type process.", Pres. at IAWPRC Int. Conf. on B i o l o g i c a l Phosphate Removal from Wastewaters, Rome, I t a l y , Sept. 28-30, 1987. Daigger, G. T.; Waltrip, G. D.; Romm, E. D. and Morales, L. M. (1986). "Enhanced secondary treatment incorporating b i o l o g i c a l nutrient removal.", Pres. 59th Annual Conf. of the Water P o l l u t . Control Fed., Los Angeles, C a l i f . Oct. 5-9, 1986. Fuhs, G. W. and Chen, M. (1975). "Microbiological basis of phosphate removal i n the activated sludge process f o r the treatment of wastewater.", Microbial Ecology, 2, 119-138. Fukase, T.; Shibala, M. and Miy a j i , Y. (1985). "Factors a f f e c t i n g b i o l o g i c a l removal of phosphorus.", Wat. S c i . 140 Tech. Vol. 17, 187-198. G a l d i e r i , J . V. (1979). " B i o l o g i c a l phosphorus removal". Chemical Engineering, Dec. 31, 1979, p. 34-35. Gerber and Winter (1984). "The influence of extended anaerobic retention time on the performance of phoredox nutrient removal plants.", Wat. S c i . Tech. Vol. 17, 81-92. Gerber, A.; Mostert, E.S.; Winter, L. T. and de V i l l i e r s , R. H. (1986). "The e f f e c t of acetate and other short-chain carbon compounds on the k i n e t i c s of b i o l o g i c a l nutrient removal.", Water SA, Vol. 12, No. 1, 7-12. Gerber, A.; Mostert, E.S.; Winter, L. T. and de V i l l i e r , R. H. (1987). "Interactions between phosphate, n i t r a t e s and organic substrates i n b i o l o g i c a l nutrient removal processes.", Wat. S c i . Tech. Vol. 19, 183-194. Gerber, A.; de V i l l i e r s , R. H.; Mostert, E. S. and van Riet, C.J.J. (1987). "The phenomena of simultaneous phosphate uptake and release, and i t s importance i n b i o l o g i c a l nutrient removal.", Pres. at IAWPRC Int. Conf. on B i o l o g i c a l Phosphate Removal from Wastewaters, Rome, I t a l y , Sept. 28-30, 1987. Jones, P. H.; Tadwalker, A. D. and Hsu, C. L. (1987). "Enhanced uptake of phosphorus by activated sludge - e f f e c t of substrate addition.", Wat. Res. Vol. 21, No. 3, 301-308. Levin, G. V. and Shapiro, J . (1965). "Metabolic uptake of phosphorus by wastewater organisms.", Jour, Water P o l l u t . Control Fed., 37, 6, 800-821. Lotter, L. H. (1987). "Preliminary observations on poly-B- hydroxybutyrate metabolism i n the activated sludge process.", Water SA. Vol. 13, No. 3, 189-191. Ni c h o l l s , H. A. (1978). "Kinetics of phosphorus transformations i n aerobic and anaerobic environments.", Pres. at the 9th IAWPR Post. Conf., Seminar, Copenhagen, June. Pros. Water Tech., 10. Ni c h o l l s , H. A. and Osborn, D. W. (1979). " B a c t e r i a l stress: a prerequ i s i t e for b i o l o g i c a l removal of phosphorus.", Jour. Water P o l l u t . Control Fed., 51, 3, 557-569. Rabinowitz, B. and Marais, G. v. R. (1980). "Chemical and b i o l o g i c a l phosphorus removal i n the activated sludge process". Research Report W32, Dept. of Civ. Eng., University of Cape Town. Rabinowitz, B. (1985). "The ro l e of s p e c i f i c substrates i n 141 excess b i o l o g i c a l phosphorus removal.", Ph.D. d i s s e r t , Univ. of B r i t i s h Columbia, Vancouver, Canada. Rensink, J . H.; Donlor, H. J . G. W. and devroes. H. P. (1981). " B i o l o g i c a l P-removal i n domestic wastewater by the activated sludge process.", 5th European Sewage and Refuse Sump., Munichan, West Germany, June 1981. Shapiro, J . ; Levin, G. V. and Zea, H. (1967). "Anoxically induced release of phosphate i n wastewater treatment.", Jour. Water P o l l u t . Control Fed, 89, 11, 1811-1818. Srinath, E. G.; Sastry, C. A. and Pilkaum S. C. (1959). "Rapid removal of phosphorus from sewage by activated sludge.", Water and Waste Treatment, 11, 410. Stevens, G. M. and Oldham, W. K. (1987). "Report on recent operational changes to the Kelowna plant.", Newsletter S p e c i a l i s t Group on Phosphate Removal i n B i o l o g i c a l Wastewater Treatment Processes, 5 ( 1 ) . Ip. Wells, W. N. (1969). "Differences i n phosphate uptake rates exhibited by activated sludges.", Jour, Water P o l l u t . Control Fed., 41, 5, 765-771. Wentzel, M. C.; Dold, P. L. ; Ekama, G. A. and Marais, G. V. R. (1985). "Kinetics of b i o l o g i c a l phosphorus release.", Wat. S c i . Tech. Vol. 17, 57-71. Wentzel. M. C. ; Lotter, L. H.; Loewental, R. E. and Marais, G. R. (1986). "Metabolic behaviour of Acinetobacter Spp. i n enhanced b i o l o g i c a l phosphorus removal - a biochemical model.", Water SA. Vol. 12, No. 4, 109-224 Chapter 9. Appendices Raw Data EXPERIMENTAL MODULE ORTHO-P AN AX AE1 AE2 AE3 AE4 1987 6-27 0 3. 5 0. 5 5 2. 0 1 6-30 2! • 0 3.0 0 1. T» 1. 1 1. 0 7-03 1. 8 5. 4 3. 5 *J • *—1 1.6 1. 7-06 1. 9 3.7 ~L • 2 1. 4 1.0 0. 7 7-09 2. 0 4. 2 2. m 0 1. 1.0 0. 8 7-13 5 8.5 3. 7 Li! • 0 2. 1 0. 8 7-20 r> 9 8. 7 3. 4 i . 3 0. 4 1. 9 7-27 3. 7 12.4 6. i . 1 0.2 0. 3 8-04 4. 6 14. 8 8. i . 0 0. 1 0. 3 8-10 3. 17. 1 10. 8 4. 9 2.6 0. 4 8-17 »j • 8 17. 8 24. 9 19. 6 15. 7 12. 8-20 4. 6 16.5 13. 5 5. 4 2.5 0. 2 8-24 5. 8 17.6 13. 6 9. 6. 4 7 8-31 4. 3 14.0 8. 4 4. 5 0.8 0. 2 9-08 3. 9 14. 6 7. 4 4. 2 2. 0. 1 9-14 4. 0 13. 1 7. 6 6 0.9 0. 1 9-21 4. 3 14. 3 11. 0 7. 9 5.8 •o a 8 9-28 5. 7 12.2 8. 1 6. 4 5.4 3. 1 10-08 3. 9 12.9 6. 9 4. 6 2.7 0. 7 10-12 5. 6 14.5 12. 2 9. 1 6.9 3. 3 10-15 4. 4 14.0 9. 6 6. 8 3.8 0. 9 10-19 4. 7 13.9 9. 1 5. 7 3.3 0. 7 10-22 4. 5 13.7 8. 2 5. 2 2 .7 1. 0 10-26 4. 2 12.2 7. 5 6. 2 3.4 1. 5 10-29 4. 3 12.7 8. 5 5. 5 3 .9 1. 4 11-03 3. 9 13.5 6. 7 O • 2 2.0 0. 5 11-05 4. 0 11.7 5. 7 3. 8 2. 8 1. 5 11 -09 4. 9 12.3 5. 7 3. 0 2 .9 1. 5 11-12 5. 0 12. 6 5. 8 3. 0 2. 5 1. 7 11-17 4. 0 10.3 5. 5 5. 5 4.5 2 m 8 11-19 4. 1 13. 2 10. 9 6. 7 3 .0 i . 1 11-23 4. 5 13.7 9. 5 5. 1 2.6 0.8 11-26 5. 0 13.4 9. 8 4. 6 2. 4 0. 5 11-30 5. 2 13.4 8. 7 6. 1 3.6 1. 5 12-03 5. 2 13. 9 10. 1 6. 9 4 .9 2 _ 8 12-07 4. 9 10.8 7. 5 5. 6 6.6 3. 2 12-08 5. 0 12.2 7. 9 5. 2 3.6 T» 5 12-10 5. 1 10.7 7. 0 4. 3 3.2 2. 4 12-14 5. 1 9.4 6. 5 4. 3 3.3 2. 3 12-15 5. 2 9.4 6. 3 4. 3 3. 1 2. 4 12-17 4. 5 9.9 6. 6 4. 3 3 .5 2. 1 12-21 3. 7 9.6 6. 2 4. 1 2 .7 1. 6 12-28 4. 6 9.8 5. 4 3. 8 2.6 1. 5 12-31 4. 6 10.9 6. 5 4. 5 3.2 2 _ 9 '7-» 6. 2 3. 6 2. 1. 8 2.0 1. 3 0. 8 6.8 5 2 • 4 ^ 1.3 1 . 3 1. 9 7.3 3. 8 0 1. 5 1.2 0. 9 0. 6 4.6 2 1. •-> 0. 7 0.7 0. 4 0. 7 6.0 3 1. 5 0. 9 0.7 0. 8 1. 3 10.0 4. 8 1. 9 0. 6 0.2 0. 2 0. 8 10. 0 4. 5 1. 6 0. ^ 0. 3 0. •**> 0. 1 13.3 7. 2 1. 5 0. 1 0. 1 0. 1 0. 3 15. 8 8. 8 1. 4 0. 1 0. 1 0. 1 0. 4 16.8 9. 7 4. 2 1. 0. 1 0. 2 8. 9 18.0 18. 5 10. 5 7. 6 3. 1 1. 5 0. 1 17.7 13. 8 6. 1 4. 0.3 0. 1 0. 1 17.9 12. 4 8. 8 5. 4 1.4 0. 1 0. 1 15. 1 11. 0 4. 6 0. 5 0. 1 0. 1 0. 0 13. 8 7. '—> 4. 0 1. 2 0.0 0. 0 0. 0 14.7 10. 2 5. 7 8 0. 1 0. 0 0. 4 12.9 9. 0 5. 3 4. 9 1.9 0. 5 1. 7 11.2 7. 7 5. 8 4. 5 2.6 1. 3 0. 2 13.2 7. 9 5. 9 1.2 0. 3 0. 6 14.5 12. 5 8. 9 6. 4 2.8 0.3 0. 3 13.3 9. 6 6. 1 3. 4 0.6 0. 2 0. 4 13. 1 8. 7 5. 3 3. 1 0.5 0. 2 0. 13.0 8. 7 5. 5 <--i ta/ a 7 1.6 0. 2 0.4 12.2 7. 5 5. 2 3. 6 1.3 0. 3 1. 0 13.0 8. 6 5. 4 3. 3 1.4 0. 6 0. 1 13.6 7. 1 3. 6 2! a 0 0.5 0. 1 0. 9 8.7 4. 4 2. 7 2. 0 1.2 0. 7 1. 0 10.8 5. 2 6 2. 1 1.6 1. 2 0. 6 10.2 4. 9 2. 0 1. 4 0. 9 0. 7 2. 6 9. 1 5. 1 3. 6 3. 0 2.3 2. 3 0. 6 11.6 10.7 4. 9 2 1 0.7 0. 0. 6 11.6 9. 5 5. 3 2. 6 0.5 0. 2 0. 1 12. 0 10. 4 5. 6 2. 0 0. 5 0. 1 0. 7 11.0 8. 3 5. 7 3. 6 2. 1 1. 2 1. 8 10.7 8. 5 5. 6 4. 5 2.5 1. 8 2. 5 9.7 7. 8 5. 1 5. 7 3.6 2. 7 1. 8 10.5 8. 8 5. 1 3. 6 2.6 2. 1 2. 0 9.0 7. 0 4. 4 3. 4 2 .7 2. 5 1. 9 7.5 5. 8 4. 0 3. 0 2.4 2." 0 2. 0 7.4 5. 9 3. 8 2. 8 2.2 2. 0 1. 6 8.0 6. 5 3. 9 2. 5 1.8 1. 4 1. 1 7.6 5. 0 3. 2 2. 3 1.6 1. 3 1. 1 7.8 5. 3 3. 6 2. 7 2.0 1. 6 2. 0 8.7 6. 1 4. 0 2. 8 2.3 1. 8 144 P04-P Cmg/L) CONTROL MODULE EXPERIMENTAL MODULE DATE TP CRTHO-P ORTHO-P MO-DA r AN AX AE 1 AE2 AE3 AE4 AN AX AE 1 AE2 AE3 AE4 ====== = = = = = === ===== ===== ===== ===== ===== ====== == === ===== ===== ===== ==== = 1383 1 -04 4. 4 11.7 7.5 4.6 3.4 2. 9 1 . 1 3. 2 7.5 4.6 2. 9 2. 1 1 . 4 1 -07 4. 11.3 T •-/ * 4.7 *i • u 1 . 7 0.9 9.7 £ . 3 4.4 2. 3 2. 2 1 . 6 1- 11 4. 11.2 6. 2 4. 4 3. 0 ~ C. 1 . 6 3. 1 £.5 4.3 3.6 3.2 2.7 1-15 4. 8 12.6 6.7 4.4 3.4 2. 1 1.5 3. 0 4. 1 O . O 2.6 1-13 4. 5 12. 8 6. & 4. 0 3. 0 1.6 1 . 3 3. 1 5.4 3.5 2. 3 2. 2 2.0 1-22 4. 8 13.3 7.0 4.7 2.7 1.6' 0.9 3. 0 * J . *_ 3.8 2.7 2. 2 1 . 8 1-27 4. 2 13.0 8.3 5.2 3. 1 1.8 1. 0 8.8 7.0 4.3 2. 5 1. 9 1-2-3 4. 4 14. 1 9.0 5.3 4.0 2.7 2.2 3.9 7.3 5. 1 T C O . O 2.8 *- • <U 2-01 4. 8 14. 1 8.4 5. 2 4. 1 1.9 1. 1 10.2 3.0 5.3 3.7 -—1 *~i *» • —1 1.6 2-04 4. 6 14.7 8.4 4.4 2. 1 0.9 0.2 10.3 8.5 4.4 2.5 1.6 0. '3 2-08 4. 4 15. 1 3.9 5. 1 2.6 1.2 0.3 10.5 8. 1 4.5 2. 3 1.9 1. 1 2-11 4. 4 14.9 8.6 4.3 2.4 1.0 0.3 10. 1 7. 1 4.2 2.5 1. 7 1. 2 2-16 4. 2 13. 6 7. 5 5.0 3.2 1.9 1.3 8.8 5.4 3 • S 2.7 2. 1 1.8 2-18 4. 7 15.0 9.7 6.0 4.0 2.3 1.7 9.8 7. 1 4.5 3.3 2.4 2.0 4. 8 14. 1 8.9 5. 0 2.5 1.0 0.5 10.3 8.4 4.7 2.7 1.6 0.9 2-25 4. 7 15.7 9. 1 5. 1 3.2 1.5 0.7 10.9 7.8 4.1 3.0 2. 1 1.4 2-29 5. 0 15. 1 9. 1 5.7 3. 7 2.4 1.6 10.5 7.2 4.6 3.2 2. 3 1.9 3-03 = 1 12.7 7.5 5. 1 3.7 2.7 2.3 8.3 5.5 3.7 3. 1 2.5 2.3 3-08 5. 0 10.3 £ • 3 4.6 3.7 2.8 7.7 4.8 3.6 3. 0 2.6 2.3 37IO 5. 0 12. 1 7.7 5. 1 3.6 2.7 2.0 3. 0 6.0 4.1 3.0 2.3 1.9 3-14 5. 0 11.3 7.2 4.6 3.2 2. 1 1.6 3.0 6.3 4.4 *J • 0 2.6 2.3 3-20 4. 9 13. 1 8.0 5. 1 3.6 2.8 2.0 3. 1 6.4 4.2 3.4 3.0 2.4 4. 7 12.9 7.4 4. 5 3.0 1.8 1.5 8.8 6.7 4.1 3.3 2.5 • w 3-25 4. 7 10.9 6.5 4.7 3. 5 2.0 1.7 8.3 6. 1 4.2 3.3 2.4 2. 1 3-28 4. 8 12. 4 6.9 4.7 3. 2 2.4 2.0 3.4 6. 1 4.4 3.4 2.8 2. 6 145 PHA as PHB Cmg/L> D A T E A N A X ' A E 1 A E 2 A E 3 A E 4 A N A X A E 1 A E 2 A E 3 A E 4 M O - D A Y C O N T R O L M O D U L E E X P E R I M E N T A L M O D U L E 1 9 8 7 a -03 1 6 . 1 4 . 9 . 1 7. 0 a 4 . 4 1 7 . 1 6 . 0 3. 3 7 . 2 6. 4 . 2 8 - 2 0 3 0 . 4 4 6 . 3 3 2 . 5 33. 2 3 . 2 1 . 5 1 - - i cr - i . - J . s 1 7 . 3 1 4 . 8 1 4 . 3 1 1 . 3 8 - 2 4 2 3 . 3 0 . 4 2 5 . 1 j • 1 7 . 3 1 4 . 4 2 6 . 5 2 1 . 0 1 7 . 1 1 3 . 9 1 1 . 1 8 . 7 8 - 3 1 2 0 . 1 1 9 . 1 6 . 4 1 2 . 1 1 1 . 3 8 . 0 >—> • 5 2 3 . 1 4 . 3 1 3 . 1 7 . 2 9 - 0 8 1 3 . 1 1 6 . g 1 6 . 4 I S . 1 1 . 0 7. ~T 1 3 . 0 1 7 . *j 1 3 . 1 1 2 . 2 1 0 . i 7 . 7 3 - 1 4 1 3 . 0 1 6 . 4 1 5 . 5 1 4 . 1 1 2 . 2 3 # 1 1 3 . 2 •-iC ^ * J • ~t 2 1 . 2 1 9 . 7 1 2 . 4 1 1 . 3 9 - 2 1 1 3 . 3 2 0 . 1 2 0 . 8 1 7 . 1 1 2 . 4 9 . 9 1 6 . 9 1 9 . 1 1 6 . 2 1 4 . 0 1 1 . 8 1 0 . 4 3 - 2 8 I S . 0 1 7 . 9 1 6 . 0 1 5 . 4 1 1 . w 9 . 5 1 7 . 9 1 3 . 3 1 4 . 1 1 4 . 2 11 . 6 9 . 1 1 0 - 0 8 1 4 . 6 1 2 . 6 1 0 . 4 3 . 1 5 . 9 5 . 7 1 3 . ^ 1 2 . 0 1 0 . 2 8 . 5 7 . 0 6 . 9 1 0 - 1 5 ••i 2 5 . 3 2 0 . 8 1 6 . 8 1 1 . 6 1 0 . 7 2 1 . 0 1 9 . 4 1 6 . 7 1 4 . 6 1 1 . 8 . 7 1 0 - 2 2 1 8 . 2 1 7 . 5 1 5 . 6 1 1 . 7 8 . 4 6 . 1 3 . 9 1 8 . 0 1 5 . 8 1 4 . 1 1 2 . 0 8 . 5 1 0 - 2 3 1 4 . 5 1 4 . 0 1 1 . 5 1 3 . 7 . 7 5 . 3 2 0 . 2 1 6 . 5 1 3 . 7 1 0 . 0 3 . 1 6 . 7 1 1 - 1 2 1 8 . 2 1 3 . 7 1 0 . 5 8 . 7 6 . S 5 . 6 1 2 . a 1 1 . 7 . 6 6 . 6 6 . 1 4 . 9 1 1 - 1 3 2 0 . 2 •>"• 1 1 8 . 5 1 4 . 6 11 . 0 9 . 0 1 7 . 3 1 9 . 8 1 5 . 7 1 2 . 1 9 . 9 7 . 9 1 1 - 2 6 0 4 2 0 . 0 1 8 . 4 11 . 7 9 . 8 2 0 . 0 m 0 1 8 . 9 1 5 . 6 1 2 . 7 1 0 . 0 1 2 - 0 3 2 1 . 2 2 1 . 1 4 . 7 1 3 . 1 a . 8 7 . 4 1 7 . 9 1 6 . 6 1 1 . 5 1 0 . 8 6 . 8 6 . 4 1 2 - 1 0 2 1 . 5 1 6 . 4 1 2 . 3 3 . 3 7 . 9 6 . 3 2 0 . 1 5 . |—I *J 1 0 . 9 8 . 7 7 . 7 7 . 0 1 2 - 2 1 1 8 . 4 1 7 . 2 1 3 . 2 11 . 0 8 . 6 7 . 1 1 5 . 4 1 2 . 9 3 . S 7 . 9 7 . 7 6 . 0 1 2 - 3 1 1 4 . 3 1 0 . 4 7 . 3 5 . 5 5 . 7 4 . 2 1 6 . 5 1 3 . 5 3 . 9 7 . 2 6 . 4 5 . 3 1 - 0 8 1 7 . 0 1 3 . 7 9 . 3 6 . 6 5 . 4 4 . 4 1 6 . 3 1 2 . 0 3 . 1 6 . 5 5 . 6 4 . 9 1 - 1 4 1 5 . >̂ 1 0 . 4 7 . 4 5 . 4 3 . 8 3 . 1 1 6 . 7 1 2 . 7 9 . 0 6 . 6 5 . 5 4 . 8 1 - 2 2 1 8 . 5 1 2 . 5 9 . 4 6 . 3 5 . 1 4 . 0 1 7 . 3 1 0 . 3 7 . 5 5 . 6 4 . 6 3 . 3 1 - 2 3 1 6 . 3 1 1 . 4 3 . 0 6 . 2 5 . 1 3 . 3 1 7 . 9 1 4 . 1 8 . 4 6 . 7 5 . 8 5 . 1 2 - 0 4 1 8 . 9 1 4 . 6 1 1 . 3 3 . 3 7 . 5 5 . 5 1 8 . '.2 1 8 . 0 1 0 . 8 8 . 8 7 . 0 6 . 9 2 - 1 1 1 6 . 6 1 3 . 3 . 7 7 . 4 5 . 4 5 . 0 1 4 . •—, 1 2 . 5 8 . 2 6 . 2 5 . 6 5 . 6 2 - 1 8 1 7 . 1 6 . 1 1 0 . 9 o 1 6 . 9 5 . 6 1 3 . 6 1 2 . 1 1 0 . 2 8 . 3 7 . 3 7 . 1 2 - 2 5 2 0 . 1 1 7 . 4 1 1 . 7 8 . 1 6 . 6 5 . 8 1 6 . 6 1 3 . 1 9 . 2 7 . 2 6 . 1 5 . 4 3 - 0 3 1 7 . 6 1 2 . 3 1 0 . 7 7 . 1 5 . 7 5 . 1 5 . 1 1 . 3 7 . 5 6 . 2 5 . 4 4 . 9 3 - 1 0 1 6 . 1 1 4 . 1 1 0 . 1 7 . 6 6 . S 5 . 0 1 4 . 1 1 2 . 9 . 6 7 . 5 6 . 0 5 . 0 3 - 2 0 1 7 . 1 3 . 6 9 . 9 7 . 8 cr o . 5 - 4 . 9 1 3 . 4 1 0 . 3 7 . 9 5 . 4 4 . 3 4 . 2 1 5 . 5 1 2 . 8 4 . a 1 2 . 3 1 0 . 5 4 . 5 1 5 . 9 1 2 . 7 2 . 4 1 3 . 5 1 1 . 6 5 . 0 146 PHA as PHB (mg/L> DATE AN Ax" AE1 AE2 AE3 AE4 MO-DAY CONTROL. MODULE 1987 8-03 IS. 7 14. 9. 1 7. 0 4. 8 -r. 4 8-20 30. 46. o T'~' 5 39. ~* _j 2'3. 9 21. 5 8-24 29. 6 30. 4 25. 1 T> T <^ 17. 8 14. 4 3-31 2f-J . 1 19. 3 16. 4 12. 1 1 1 . 8 8. 0 9-03 i 9, 1 16. 3 16. 4 IS. —> 1 1 . 0 7. 7 9-14 19. 0 16. 4 15. cr *J 14. 1 12. 9. 1 9-21 19. 9 20 • 1 20. 8 i 7 # 1 13. 4 9. 9 9-28 13. 0 17. 9 16. 0 15. 4 11 . 3 9. 5 10-08 14. 6 12. 6 10. 4 9. 1 5. 9 5. 7 10-15 22. '2 X J . 20. 8 16. 8 11 . 6 10. 7 10-22 13. 2 17. 5 15. 6 11. 7 8. 4 6. T> 10-29 14. cr 14. 0 11 . e-u 13. -~y 7. 7 5. 8 11-12 18. T< 13. 7 10. 5 8. 7 6. 8 5. 6 11-19 20. 2 1 18. 5 14. 6 11. 0 9. 0 11-26 lx!2 • 0 22 • 4 20. 0 IS. 4 11. 7 9. 8 12-03 21. 2 21. 2 14. 7 13. 1 8. 8 7. 4 12-10 21. 5 16. 4 12. 9. 9 7. 9 6. 9 12-21 18. 4 17. -j 13. 2 11 . 0 8. 6 7. 1 12-31 14. 3 10. 4 7. 8 5. 5 5. 7 4. 1988 1-08 17. 0 13. 7 9. 6. 6 5. 4 4. 4 1-14 15. 2 10. 4 7. 4 5. 4 8 —> • 1 1-22 18. 5 12. s 9. 4 6. 9 5. 1 4. 0 1-29 16. w 11. 4 9. 0 6. •z> 5. 1 Ti 9 2-04 18. 9 14. 6 11 . 9 9. 3 7. 5 5. 5 2-11 16. 6 13. 2 9. 7 7. 4 5. 4 5. 0 2-18 17. T> 16. i 10. 9 8. 1 6. 9 5. 6 2-25 20. 1 17. 4 11. 7 8. 1 6. 6 5. 8 3-03 17. 6 12. 8 10. 7 7. 1 5. 7 5. 3 3-10 16. 1 14. 1 10. 1 7. 6 6. 6 5. 0 3-20 17. 2 13. 6 9. 9 7. 8 5. 5 4. 9 3-22 15. 5 12. 8 4. 8 3-25 15. 9 12. 7 T> 4 AN AX AE1 AE2 AE3 AE4 EXPERIMENTAL MODULE 17.3 IS. 0 •3 _ 9 7. 2 6. 4. 23. 1 •-.cr s 17. 9 14.8 14. T> 1 1 . 9 26. 5 21 . o 17. 1 13.9 1 1. l 8. 7 23. 5 14. 3 13. 1 9. 9 7. 19.0 17. 3 13. 1 12.2 10. 1 7. 7 19.2 - i cr —\ 21 . x' 19.7 12. 4 11 . IS. 9 19. 1 IS. 2 14.0 11. 8 10. 4 17.9 13. 3 14. 1 14.2 11 . 6 9. 1 13.3 12. 0 10. '^i 8. 5 7. 0 6. 9 21.0 19. 4 16. 7 14.6 1 1 . 3 8. 7 19.9 18. 0 15. 8 14. 1 12. 0 8. 5 20. 2 16. 5 13. 7 10. 0 8. 1 6. 7 12.8 11. 7. 6 6.6 6. 1 4. 9 17.8 19. 8 15. 7 12. 1 9. 3 7. 9 20. 0 Xl J— • 0 18. 9 15.6 12. 7 10. 0 17.9 16. 6 11 . 5 10.8 6. 8 6. 4 20.2 15. _/ 10. 9 8.7 7. 7 7. 0 15. 4 12. 9 9. 6 7.9 7. 7 6. 0 16.5 13. 5 8. 9 7.2 6. 4 5. 3 16.3 12. 0 9. 1 6.5 5. 6 4. 9 16. 7 12. 7 9. 0 S.S 5. 5 4. 8 17. 3 10. 9 7. cr U 5. 6 4. 6 3. 9 17.9 14. 1 8. 4 6.7 5. 8 5. 1 18. 2 18. 0 10. 8 8.8 7. 0 6. 9 14.2 12. 5 8. 6.2 cr o • 6 5. 6 13.6 12. 1 10. 2 8.3 7. 3 7. 1 16.6 13. 1 9. T> 7.2 6. 1 5. 4 15.2 11. T> 7. 5 6. 2 5. 4 4. 9 14. 1 12. *L 9. 6 7.5 6. 0 5. 0 13.4 10. 9 7. 9 5.4 4. 9 4. 2 f2.3 10. 5 4. 5 13.5 11. 6 5. 0 TOTAL SUSPENDED SOLIDS, TSS (mg/L) DATE/CUM.DAY EXPERIMENTAL MODULE MO-DAY AN AX AE1 AE2 AE3 AE4 EPF ======= ===== ======== 1937 £-27 1 984 2131 2323 2662 2163 2186 10 £-30 4 915 1760 1329 1355 1773 1323 3 7-03 ~7 / 303 1591 1706 1773 1317 1780 8.2 7-06 10 893 1899 1734 1842 Xl X- 1876 7.8 7-09 13 862 1S38 1914 1962 1346 1904 10.8 7-13 17 863 1922 1942 1874 1950 1863 3.6 7-16 20 816 1752 1722 1740 1304 1776 1 1 7-20 24 368 2084 1928 1974 2030 1312 7.2 7-23 27 933 2198 2078 2110 2120 2094 8.8 7-27 31 1 196 2496 2292 2294 2300 2236 5.2 7-30 34 1140 2430 2404 2286 2350 2280 21.8 8-04 39 1 133 2580 2640 2556 2532 2502 9.8 8-06 41 1212 2740 2832 2628 2580 2516 11.2 8-10 45 1037 2436 2583 2400 2457 2383 11.4 8-13 48 11 14 2586 2629 2586 2680 2603 13.4 8-17 52 1071 2480 2509 2546 2434 2451 8.4 8-20 55 1357 2549 2551 2757 2697 2603 12.6 8-24 59 1520 2700 2629 2663 2751 2537 16.5 8-27 62 1391 2637 25// 2863 2949 2709 14 8-31 66 1340 2754 2837 2814 2994 2934 10.4 9-03 69 1434 2874 2866 2794 2929 2849 9.8 9-08 74 1289 2620 2611 2714 2743 2711 11.4 9-10 76 1294 2697 2654 2817 2957 2786 10.4 9-14 80 1414 2354 2829 2837 2763 2751 12.8 9-21 87 1403 2689 2900 2877 3020 2949 11.8 9-28 94 1366 2817 2920 3057 3049 2877 19.5 10-08 104 1226 2317 2411 2460 2423 2271 13. 2 10-12 108 1389 2689 2906 2929 2826 2746 12.6 10-15 111 1380 2543 2937 2814 2391 2703 8.6 10-19 115 1477 2894 3077 2997 2940 2834 10 10-22 118 1351 2617 2974 2757 2786 2503 10.8 10-26 122 1360 2671 3203 3309 3037 2703 10 10-29 125 1480 2771 3000 2926 2737 2706 10.4 11 -03 130 1409 2800 3371 3063 2349 2891 10 11-05 132 1366 2700 2963 2789 2866 2671 10 11 -09 136 1686 2700 2869 2823 2866 2746 10 11-12 139 1380 2711 2789 2709 2769 2671 10 11-17 144 1483 2717 2857 2729 2831 2669 10 11-19 146 1463 2880 291 1 2654 2680 2594 11.2 11-23 150 1640 3057 3229 3443 3003 2971 10 11-26 153 1591 2914 3226 3266 3306 2940 5. 6 1 1-30 157 1688 3088 3016 2960 3068 3228 6 12-03 160 1636 3116 3092 3380 2396 3116 6.6 12-07 164 1512 2748 3228 3652 2992 2704 6 12-10 167 1920 3188 3336 3124 3212 3128 6 12-14 171 1640 2816 3212 2892 2908 2824 5 12-17 174 1572 2836 3084 2732 2988 2784 12-21 178 1708 2980 3080 2972 3232 2960 12-28 185 1792 2988 2992 2916 2396 2928 12-31 188 1608 2840 2952 2788 2328 2864 10.6 148 T O T A L S U S P E N D E D S O L I D S , T S S Cmg/L!) D A T E / C U M . D A Y E X P E R I M E N T A L M O D U L E M O - D A Y A N A X A E 1 A E 2 A E 3 A E 4 E F F 1 9 8 3 1 - 0 4 1 9 2 1 5 9 2 2 S 9 6 3 0 6 4 2 9 2 4 3 0 3 2 2 8 9 2 1 - 0 7 1 9 5 1 u l ' u 2 9 2 8 2 9 5 6 3 0 4 4 3 0 3 8 6. 4 1 - 1 1 1 9 9 1 6 3 2 3 1 1 6 3 2 4 4 3 1 1 2 3 2 2 0 3 1 0 0 1 - 1 5 2 0 3 1 6 8 3 3 0 6 8 3 1 7 2 3 0 0 8 3 1 7 6 3 0 8 4 1 3 . 4 1 - 1 8 2 0 6 1 6 1 6 2 9 4 0 3 0 6 4 2 9 8 4 3 0 5 2 2 9 2 8 1 - 2 2 2 1 0 1 5 1 6 2 7 3 2 2 7 4 8 2 6 7 2 2 7 7 6 2 6 3 6 1 - 2 7 2 1 5 1 6 0 4 2 7 2 8 2 8 0 0 2 6 9 6 2 8 3 6 2 6 7 2 1 - 2 9 2 1 7 1 6 1 2 2 7 0 4 2 8 7 6 2 7 4 8 2 8 5 6 2 7 4 4 8 . 2 2 - 0 1 2 2 0 1 4 8 0 2 8 4 8 2 7 6 0 2 7 5 4 2 7 6 0 2 7 0 8 2 - 0 4 •"<••> ^ ^- 1 5 0 7 2 9 6 5 2 9 5 5 2 9 4 5 2 9 1 0 2 9 4 5 7 . 8 2 - 0 8 2 2 7 1 6 0 5 2 8 6 5 2 8 2 5 2 8 3 5 2 8 2 5 2 8 1 0 2 - 1 1 2 3 0 1 5 9 5 2 6 9 5 2 7 1 0 2 6 3 5 2 7 4 0 2 6 7 5 2 - 1 6 2 3 5 1 4 0 5 2 9 1 5 2 6 1 0 2 5 8 5 2 7 2 5 2 6 7 0 2 - 1 8 2 3 7 1 4 8 0 2 7 9 0 2 6 7 5 2 6 1 5 2 7 4 0 2 7 5 5 2 — 2 2 2 4 1 1 4 6 5 2 7 7 5 2 6 3 5 2 6 9 0 2 7 6 0 2 7 0 0 8 . 8 2 4 4 1 5 1 0 2 7 2 5 2 7 0 5 2 6 5 0 2 7 5 0 2 7 6 5 2 - 2 9 2 4 8 1 4 1 5 2 9 1 5 2 8 8 0 2 8 6 5 2 9 3 5 2 8 1 5 3 - 0 3 2 5 1 1 4 9 0 2 9 4 0 2 8 4 5 2 8 3 0 2 9 7 5 2 9 9 0 7 . 4 3 - 0 8 2 5 6 1 5 0 0 2 7 5 0 2 7 7 5 2 7 7 5 2 7 8 5 2 8 2 0 3 - 1 0 2 5 8 1 3 9 5 2 7 4 5 2 7 1 5 2 6 5 5 2 8 3 0 2 6 4 0 3 - 1 4 2 6 2 1 <JWJ •-. OÔ ! 2 4 1 0 2 4 5 0 2 4 3 5 2 5 0 5 3 - 2 0 2 6 8 1 2 7 5 2 3 9 0 2 4 5 0 2 4 5 5 2 4 9 5 2 4 6 5 /-V .—,.-, 2 7 0 1 2 7 5 2 6 2 5 2 5 9 5 2 5 2 0 2 6 1 0 2 5 9 0 3 - 2 5 2 7 3 1 3 2 5 ' 2 7 9 5 2 8 4 0 2 7 3 5 2 8 4 0 2 7 1 0 3 - 2 8 2 7 6 1 1 1 5 2 3 4 5 2 4 2 5 2 3 9 0 2 4 0 0 2 3 6 0 TOTAL S U S P E N D E D S O L I D S , TSS Cmg/L ) D A T E / C U M . DAY CONTROL MODULE MO-DAY AN AX AE 1 A E 2 A E 3 AE4 E F F 1337 6 - 2 7 1 9 3 3 3 3 1369 2 0 6 9 2 0 0 8 1735 16 6 - 3 0 4 9 7 4 2171 1943 1 9 3 3 1391 2 0 1 7 1 3 . 3 7 - 0 3 7 830 2 0 3 7 1331 1829 1821 1773 1 3 . 6 7 - 0 6 10 7 3 3 1331 2 1 1 0 1325 2 1 0 5 2 1 1 6 1 1 . 3 7 - 0 9 13 330 1862 1343 ISO 6 1906 1764 3 7 - 1 3 17 7 4 0 1636 1896 2 3 0 0 2 0 9 4 2 1 5 8 14 7 - 1 6 2 0 7 7 4 1758 1718 1816 1870 1844 1 6 . 4 7 - 2 0 2 4 6 8 2 1782 1748 1926 1966 2 1 5 4 1 3 . 8 7 - 2 3 2 7 776 1954 1926 1936 2 0 9 6 2 1 5 0 1 5 . 8 7 - 2 7 31 1062 2 1 9 4 2 1 3 4 2 2 1 6 2 3 1 2 2 1 6 8 8 . 8 7 - 3 0 34 3 9 4 2 3 5 0 2 2 9 4 2 2 8 8 2 3 6 6 2 2 4 4 7 . 5 8 - 0 4 3 9 1060 2 5 3 8 2 6 5 0 2 5 5 8 2 4 8 2 2 4 8 8 9 . 4 8 - 0 6 41 1054 2 8 2 8 2 8 6 0 2 6 9 6 2 5 4 8 2 5 7 2 1 3 . 8 8 - 1 0 4 5 1020 2 5 2 3 2 4 0 0 2 4 9 7 2 4 4 0 2 5 0 0 1 3 . 2 8 - 1 3 4 3 1094 2691 2 6 4 6 2 7 0 6 2 6 6 3 2 7 6 3 1 1 . 8 8 - 1 7 52' 1 0 0 3 2 4 0 9 2 4 7 7 2 4 3 1 2 4 6 3 2 6 0 6 2 0 . 8 8 - 2 0 5 5 1090 2 5 7 4 2 5 8 9 2 6 4 3 2 6 3 7 2 6 2 3 1 9 . 3 8 - 2 4 5 9 1427 2 6 0 6 2 5 5 7 2 6 7 1 2 6 4 9 2 7 0 3 15 3 - 2 7 6 2 1346 2 6 5 4 2 6 8 3 3 0 0 0 2 6 6 9 2 6 8 6 13 8 - 3 1 6 6 1235 2 7 6 9 2 8 5 7 2 8 9 1 2 8 2 6 3 0 4 0 11 9 - 0 3 6 9 1500 2 9 8 9 3011 3 0 0 0 2 8 2 6 2 9 7 4 3 . 8 9 - 0 8 74 1257 2 6 6 6 2 7 4 0 3 3 3 7 2 6 8 3 2 6 9 7 1 2 . 6 9 - 1 0 7 6 1 2 9 7 2 6 3 4 2 5 8 3 2 6 0 0 3 3 4 9 2 9 8 6 12 9 - 1 4 8 0 1643 2971 2 3 6 6 2 8 3 3 2 8 8 3 2 3 8 0 1 3 . 4 9 - 2 1 8 7 1 4 8 3 2 7 4 0 2 9 0 3 3 0 5 4 2 8 6 9 2 7 8 6 14 9 - 2 8 94 1 3 8 3 2 7 3 4 2 9 0 0 3 0 8 3 2 7 6 6 2 7 2 6 12 1 0 - 0 8 104 1 2 3 7 2 2 4 0 2 3 6 6 2 5 3 4 2 2 5 4 2351 1 0 . 4 1 0 - 1 2 108 1 3 2 3 2611 2 8 7 4 2 8 8 6 2 5 9 7 2 6 4 3 1 4 . 8 1 0 - 1 5 111 1251 2 4 9 1 2 9 3 7 2 8 5 7 2 5 5 4 2 5 8 0 ' 1 0 . 4 1 0 - 1 9 115 1331 2771 3011 2 8 7 7 2 7 7 4 2 9 8 9 10 1 0 - 2 2 118 1 3 2 3 2 5 5 7 2 7 6 8 2 5 6 6 2 4 6 0 2371 1 4 . 4 1 0 - 2 6 122 1326 2 6 6 3 3 0 8 3 2 9 7 7 2 6 7 7 2 6 7 4 10 1 0 - 2 9 125 1269 2 6 8 6 2 7 6 6 3 0 8 3 2551 2491 1 1 . 6 11 - 0 3 130 1317 2 6 6 0 3111 2 8 2 9 2 7 0 3 2 5 2 9 10 1 1 - 0 5 132 1266 2 5 2 9 2 9 3 4 2 7 9 7 2 6 4 9 2 6 4 6 10 1 1 -09 136 1254 2531 2 8 2 0 2 7 4 3 2 7 1 4 2 7 0 6 10 1 1 - 1 2 139 1209 2 4 3 7 2 6 1 4 2 5 0 3 2 5 0 9 2 4 4 6 10 1 1 - 1 7 144 1203 2 3 4 6 2 6 2 0 2 5 1 1 2 4 6 3 2 3 2 9 10 1 1 - 1 3 146 1237 2 3 7 7 2 6 2 3 2 4 2 0 2351 2 3 1 4 1 0 . 8 1 1 - 2 3 150 1317 2 6 4 0 2831 3 0 3 7 2 5 8 9 2 6 3 4 10 1 1 - 2 6 153 1254 2 6 0 3 3 0 0 0 3 2 4 6 2 5 6 0 2 6 0 3 7 . 6 11 - 3 0 157 1376 2 7 4 3 2 9 4 0 2 3 6 4 2 5 8 8 2 6 6 0 7 . 5 1 2 - 0 3 160 1484 2 8 7 6 3 0 4 8 3 0 9 6 2 7 0 0 2 7 6 8 5 . 4 1 2 - 0 7 164 1116 2 5 3 2 3 0 3 6 3 4 4 0 2 4 4 4 2 3 5 6 5 1 2 - 1 0 167 1596 2 8 4 4 2 8 8 8 2 8 7 6 2 8 3 6 2 7 3 2 6 . 4 1 2 - 1 4 171 1232 2 4 2 8 2 6 1 2 2 6 4 0 2 4 0 0 2 4 0 8 5 1 2 - 1 7 174 1204 2 3 8 4 2 7 1 2 2 8 0 4 2 2 3 6 2 4 0 0 1 2 - 2 1 178 1376 2 8 6 8 2 8 0 4 2 9 4 4 2 7 2 8 2 6 8 0 1 2 - 2 8 185 1388 2 5 4 8 2 5 9 2 2 5 4 0 2 6 6 8 2 4 9 2 1 2 - 3 1 188 1076 2 1 6 8 2 2 5 2 2 1 3 2 2 6 9 6 2 5 1 6 1 4 . 8 TOTAL SUSPENDED S O L I D S , T S S ( m g / L ) D A T E / C UM.DAY CONTROL MODULE MO-DAY AN AX AE 1 A E 2 AE3 AE4 E F F 1988 1 -04 192 1 184 2 3 7 6 2 6 8 8 2 3 7 2 2 3 9 2 2 3 9 6 1 -07 195 1296 2w'6S 2 5 0 4 2 4 3 6 2 6 6 0 2 5 4 8 1 1 . 2 1-11 199 1212 2 6 2 0 2 7 3 2 ' 2 6 4 4 2 5 6 0 2 4 7 2 1 - 1 5 2 0 3 1083 2 4 0 4 2 4 5 2 2 2 3 0 2 3 2 4 2 3 3 2 1 1 . 2 1 -18 2 0 7 1084 2 3 4 8 2 3 2 4 2 2 6 4 2 2 9 6 1 -22 2 1 0 1080 2 2 4 0 2 2 6 0 2 1 8 4 2 2 1 2 2 1 6 4 1 -27 2 1 5 1052 2 1 6 4 2 1 6 3 2 1 3 6 2 1 8 0 2 1 6 0 1 -29 2 1 7 1032 2 1 1 2 2 1 5 6 2 1 3 2 2 1 6 8 2 1 2 8 1 1 . 6 2 - 0 1 2 2 0 1012 2 1 4 8 2 0 8 8 2 0 1 2 2 0 4 8 2 0 8 8 2 - 0 4 2 2 3 1030 2 2 0 5 2 1 8 0 2 2 0 0 2 2 3 0 2 2 0 0 12 2 - 0 8 2 2 7 1060 2 1 8 5 2 2 0 5 2 1 8 0 2 2 0 5 2 1 4 5 2 - 1 1 2 3 0 9 2 5 2 0 9 0 2 0 6 5 2 1 0 5 2 1 1 5 2 1 5 0 2 - 1 6 2 3 5 980 2 0 7 5 2 0 4 5 2 0 9 0 2 3 2 5 2 1 2 0 2 - 1 8 2 3 7 1075 2 4 1 5 2 1 9 0 2 1 7 0 2 2 4 0 2 1 5 5 2 - 2 2 241 1075 2 3 2 5 2 2 5 5 2 2 4 5 2 3 9 5 2 3 0 5 8 . 8 2 - 2 5 2 4 4 1 155 2 3 3 5 2 3 0 5 2 2 4 0 2 3 4 0 2 3 3 0 2 - 2 9 2 4 8 1 135 2 5 2 5 2 5 2 0 2 4 9 5 2 5 0 5 2 5 0 0 3 - 0 3 251 1160 2 5 6 0 2 5 1 0 2 4 5 5 2 4 6 0 2 6 3 0 1 1 . 2 3 - 0 8 2 5 6 1075 2 4 3 5 2 4 4 5 2 4 0 0 2 4 5 5 2 4 0 0 3 - 1 0 2 5 8 1120 2 4 3 0 2 3 9 0 2 3 1 0 2 4 0 0 2 3 6 5 3 - 1 4 2 6 2 1030 2 2 1 5 2 2 2 0 2 2 6 0 2 2 1 5 2 2 1 0 3 - 2 0 2 6 8 1 130 2 3 3 5 2 3 6 5 2 3 2 5 2 3 2 5 2 5 0 5 3 - 2 2 2 7 0 1170 2 6 1 5 2 5 7 5 2 5 5 5 2 6 0 5 2 6 2 5 3 - 2 5 2 7 3 1170 2 5 1 0 2 7 7 5 2 4 3 0 2 4 7 0 2 5 7 5 3 - 2 8 2 7 6 1030 2 1 4 0 2 4 0 0 2 1 9 5 2 2 3 0 2 1 6 0 151 NH3-N Cmg/L) D A T E C O N T R O L MODULE MO-DA F AN A n X A E 1 A E 2 A E 3 ====== : = = = = = ===== = = = == === == : = = = = = === = : 1 3 8 7 7 - 2 7 1 5 . 6 1 1 . 3 7. 4. 0 . 9 0. 1 8 - 0 4 1 6 . 5 12 7. £ 5. 1 1. 2 0. 1 8 - 1 0 1 8 . 4 1 2 . 4 8 2 a •mi 0. 1 0. 1 8 - 1 7 2 5 . 7 1 6 . 5 11 . 5 5 0 . 6 0.6 8 - 2 4 1 5 . 8 1 1 . 8 7. 8 1. 7 0. 1 0. 1 8-31 1 4 . 6 1 0 . 8 7. 1 1 . 5 0.2 0 . 2 9 - 0 8 1 1 . 9 8 . 5 5. 4 0. 6 0.2 0. 1 9 - 1 4 1 0 . 8 8 . 5 ar 5 2 0 . 2 0 . 2 9-21 1 1 . 2 8. 1 5. 7 1. 5 0 . 3 0.2 9 - 2 8 1 1 . 8 8.4 5. 5 0. 6 0. 1 0. 1 1 0 - 1 2 1 3 . 7 9.5 6. 6 1. a 0.2 0. 2 1 0 - 1 5 1 3 . 8 3 6. 1 1 0.2 0 . 3 1 0 - 2 2 1 3 . 2 8 . 3 5. 6 1. 3 2. 1 0 . 9 11 - 0 2 2 0 . 9 9.4 6. 5 1. 1 0. 1 0. 1 1 1 - 0 5 1 8 . 7 1 3 . 5 9. 1 4. 8 0.8 0. 1 11 - 0 9 2 3 . 4 1 6 . 5 1 1 . 2 6. 5 1.3 0.2 1 1 - 1 2 2 8 . 9 1 9 . 7 12. 7 7. 7 0 . 3 1. 1 1 1 - 1 9 9. 1 6 . 5 4. 1 0. 6 0.2 0. 1 1 1 - 2 6 9.5 7 . 9 5. 4 1. 4 0 . 3 0. 1 1 2 - 3 1 1 4 . 7 1 0 . 1 6. 9 2 B 9 0.4 0 . 3 1 9 8 8 1-07 1 4 . 1 9.7 6. 5 2. 6 0. 1 0 . 2 1-15 2 0 . 8 1 4 . 1 9. 2 4. 9 1. 1 0 . 2 1-22 2 2 . 5 1 5 . 7 1 0 . 5 5. 9 1.7 0.4 1-29 1 1 . 5 8 5. 4 1 0 . 9 0.4 2 - 0 4 1 5 . 6 10 6. 3 3 0. 15 0.3 2 - 1 1 1 4 . 2 10 6. 4 2. 3 0.2 0 . 2 2 - 1 8 1 5 . 1 9.5 6. 4 2. 6 0.2 0 . 3 2 - 2 5 1 7 . 4 1 1 . 1 7. 4 3 . 3 0 . 3 0 . 3 3 - 0 3 13 1 1 . 9 7. 5 4. 2 0 . 9 0. 1 3 - 2 0 1 4 . 4 9.6 6. 2 3. 1 0 . 5 0. 1 3 - 2 5 1 4 . 1 9. 1 6 3. 8 0 . 9 0.4 E X P E R I M E N T A L MODULE A E 4 AN AX A E 1 AE '2 A E 3 A E 4 :_ = _= ====== ===== ===== = = = == === == = = = = : 0. 1 1 1 . 5 7. 7 4 . 5 0. 5 0 0 0. 1 1 1 . 9 8.2 4.2 0. 0. 1 0. 1 0. 2 1 3 . 4 9.2 3 . 3 0. 1 0. •—> 0. 1 0. 6 1 7 . 6 1 2 . 8 6. 1 0. 6 0. 7 0. 6 0. 1 1 1 . 8 7. 3 2. 2 0. 2 0. 1 0. 1 0. i 11 7.2 2 . 2 0. 1 0. 1 0. 1 0 8.8 5 . 5 0.8 0. 1 0. 1 0 0. 1 8 .5 5 . 3 1.5 0. 1 0. 1 0. 1 0. 1 9 6.2 0.7 0. 1 0. 1 0. 1 0. 1 8 6 0.6 0 0 0 0. 3 9.8 6.8 2 . 4 0. 1 0. 2 0. 1 0. 2 9.8 7 2 . 2 0. 1 0 . 2 0. 1 0. 1 9 6. 1 1.9 0. 2 0. 1 0 0. 9.8 6.5 1.8 0. 1 0. 1 0. 1 0. 2 1 3 . 6 9.2 4 . 8 0. 8 0. 1 0. 1 0. 1 1 6 . 9 1 1 . 6 7.2 1. 2 0. 1 0. 1 0. 2 0 . 6 1 3 . 6 1 1 . 8 0. 2 0. 4 0 0. 1 6.7 4.3 0 . 5 0. 1 0. 1 0 0. 1 8. 1 5 . 4 5 . 3 0. 1 0. 1 0 0. 2 1 0 . 5 7. 1 2 . 6 1. 4 0. 1 0. 1 0. 1 1 0 . 5 7. 1 3.4 0. 3 0. 1 0. 1 0. 1 1 4 . 3 9.6 4 . 8 0. 4 0. 1 0. 1 0. 1 1 5 . 7 1 0 . 6 5 . 2 0. 7 0. 2 0. 1 0. 2 8 . 5 5 . 9 2. 1 0. 4 0. 2 0.2 0. 3 1 0 . 5 6.9 3 . 5 0. 2 0. 2 0. 1 0. 5 10 6.4 2 . 8 0. 1 0. 1 0 . 3 0. 2 10 6.2 2 . 6 0. 1 0. 1 0. 1 0. 2 1 1 . 4 7 . 6 3 . 5 0. 1 0. 1 0. 1 0. 3 1 1 . 9 7.7 3 . 9 0. 4 0. 2 0. 1 0. 2 9.7 6 . 5 3.4 0. 6 0. 1 0 . 2 0. 3 9.3 6.2 3 . 3 0. 4 0. 1 0. 1 NOx-N (mg/L.) D A T E C O N T R O L MODULE E X P E R I M E N T A L MODULE MO-DA AN AX A E 1 A E 2 A E 3 A E 4 AN AX A E 1 A E 2 A E 3 A E 4 ====== ===== ===== === -===== ===== ===== ==== ===== === : = = = =: = : = = S = = : = = = = : 1 3 8 7 • 6- 2 7 0.1 0. 9 4. 1 3.7 6. 1 6. 8 0. 4 0. 5 4. 5 6.6 6.4 7. 4 6 - 3 0 0 . 0 0. 0 4. 4 6.4 7.2 7 . 3 0. 8 0.9 3. c _l 6.4 7.4 6.6 7 - 0 3 0 . 0 0. 1 2. 8 6.3 7. 0 6. 6 0. 9 0. 1 +1 * 0 4 . 3 7 . 5 7 . 3 7 - 0 6 0.2 1.2 4. 4 6.7 7.0 6 . 3 0. 1 0.5 4. & 7.3 7.7 7. 3 7 - 0 3 0.0 0. 6 4. 7 6.9 7. 1 6 . 9 0. X . 0.3 4. 4 6.3 7. 5 7 . 3 7 - 1 3 0.6 0.6 4. 8 6.8 6.7 6.6 0. 0 0. 1 4. 4 6.0 7.0 6.8 7 - 2 0 0. 1 1.0 5. hJ 7.7 3 . 9 7 . S 0. 2 0.0 4. a 6. 7 6. 8 7. 7 7 - 2 7 0. 1 0. 1 3. 3 6.7 7 . 5 7 . 2 0. 0 0.0 3. 2 6.3 8.0 7 . 5 8 - 0 4 0.0 0.2 2 1 6.3 6 . 9 7 . 0 0. 0 0. 1 3. 2 7. 2 7.2 7.2 8 - 1 0 0 . 3 0 . 3 4. 0 6.2 5 . 2 5 . 1 0. 1 0. 1 4. 0 7. 1 7.2 7. 1 8 - 1 7 0.2 0. 3 1 . * ? _J 3 . 5 3 . 3 3 . 8 0. 1 0. 1 3. 3 6.6 8.0 7 . 8 8 - 2 0 0.0 0.0 0. 1. 1 0 . 9 0 . 2 0. 1 0.0 9 5 . 6 5 . 8 2 . 8 8 - 2 4 0.0 0.0 0 3.5 3 . 0 2 . 8 0. 0 0 . 0 5. 0 5. 6 5. a 5 . 7 8 - 3 1 0 . 0 0.2 3. 8 5 . 3 5 . 0 4 . 7 0. 0 0.0 7 4.8 4.4 4 . 3 3 - 0 8 0.0 0.0 3. 2 2 . 3 3 . 2 3 . 5 0. 0 0 . 0 y-f a 2 3 . 5 3 . 9 4 . 2 3 - 1 4 0.0 0 . 0 1. 1 2. 4 2. 2 2. 1 0. 0 0 . 0 1 . 2 1. 7 1.3 1. 1 9-21 0. 1 0.2 1. 9 2.4 1.8 1.4 0. 0 0.0 4. 0 4.2 4.2 4. 3 9 - 2 8 0 . 3 0. 1 4. 4.4 4 . 3 4 . 6 0. 3 0. 1 4. 3 4 . 6 4.6 4 . 7 1 0 - 0 8 0.0 0.0 4. 4 4. 1 4 . 4 4 . 3 0. 0 0 . 0 4. 7 4.4 4 . 5 4 . 5 1 0 - 1 2 0 . 0 0 . 3 2. 6 3. 1 2 . 3 3 . 2 0. 0 0.0 1. 7 3 .4 3. 1 2 . 9 1 0 - 1 5 0. 1 0 . 0 • 6 3.8 3 . 7 3 . 5 0. 1 0 . 0 2. a 4 . 3 4.2 4 . 0 1 0 - 1 9 0.0 0 . 0 1. 9 3 . 3 3 . 6 3. 5 0. 0 0.0 2. 4 4.7 4 . 3 4.2 1 0 - 2 2 0.0 0. 0 3. 1 4 . 3 4 . 6 4 . 8 0. 0 0. 0 ^ m 7 4.7 4.8 5 . 0 1 0 - 2 6 0. 1 0.8 9 5 . 3 5 . 8 5 . 6 0. 0 0.0 3. 0 5 . 5 5 . 8 5 . 7 1 0 - 2 9 0.2 0. 1 5. 1 5 . 8 6. 2 6 . 9 0. 0 0 . 2 4. 0 5. 9 6. 1 6. 9 1 1 - 0 3 2. 9 7 . 3 8 . 8 9.2 2. 7 8.0 8.4 8. 1 1 1 - 0 5 0.5 1.4 a 9.0 9.7 9 . 9 0. 1 0. 1 *-t W • 9 9.0 9.9 1 0 . 4 1 1 - 0 9 0 . 0 0 . 0 5. 4 11.& 1 3 . 1 1 3 . 1 0. 0 0.0 5. 4 1 1 . 9 1 3 . 7 1 3 . 6 1 1 - 1 2 0.0 0. 1 5. 0 1 0 . 6 1 1 . 4 1 1 . 9 0. 0 0. 1 5. 2 1 1 . 0 1 3 . 1 1 3 . 7 1 1 - 1 7 1.0 1.4 7. 0 14 . 1 1 5 . 9 1 5 . 9 0. 4 0 . 9 6. 2 1 3 . 2 1 4 . 9 1 5 . 8 1 1 - 1 3 0.0 0 . 0 3. 3 4 . 5 4 . 5 4 . 6 0. 0 0 . 0 3. 4 4 . 7 4 . 8 4 . 6 1 1 - 2 3 0 . 0 0 . 0 3. 2 4 . 7 4 . 7 5 . 0 0. 0 0 . 0 4. 1 4 . 5 4.6 4 . 7 1 1 - 2 6 0. 1 0.0 3. e 5 . 9 6.0 6. 1 0. 3 0 . 0 5. 0 5 . 8 5 . 7 5 . 7 1 1 - 3 0 0. 1 0. 1 4. 4 6.9 6. 1 6 . 6 0. 1 0 . 0 4. 9 6.4 6.5 6 . 5 1 2 - 0 3 0.2 0 . 0 4. 0 6. 5 6.2 5 . 9 0. 4 0.0 4. 1 6. 3 6. 1 6.2 1 2 - 0 7 0. 1 0 . 0 3. 7 6.8 7.2 7 . 3 0. 1 0.0 3. 0 5 . 9 6.9 7 . 0 1 2 - 1 0 0 . 0 0.0 4. 0 7 . 0 7 . 0 7 . 4 0. 0 0.0- 4. 0 6.9 7 . 3 7 . 6 1 2 - 1 4 0. 1 1.2 4. 2 7.4 7 . 5 7.4 0. 0 0. 1 3. 9 7.4 7.4 7. 1 1 2 - 1 7 0 . 0 0. 0 5. 0 7. 1 7.4 7 . 4 0. 0 0. 0 3. 7 7 . 5 7 . 6 7 . 9 1 2 - 2 1 0 . 0 0 . 7 5. 7 7 . 5 7 . 6 7 . 5 0. 0 0.3 5. 0 7 . 5 7 . 6 7 . 5 1 2 - 2 8 0.5 0. 1 5. & 7.4 7.4 7 . 9 0. 3 0. 1 5. 7 7 . 6 7 . 6 7 . 7 1 9 8 8 1-04 0. 1 0. 1 4. 1 7.2 7. 6 7 . 7 0. 1 0. 1 4. 7 7. 7 7 . 3 7. 8 1-11 0.2 0 . 3 5. 8.4 9.5 1 0 . 5 0. 1 0. 1 2. 1 7.0 a.o S . 9 1 - 1 5 0. 1 0. 4 4. a 9.5 1 0 . 7 1 1 . 4 0. 1 0. 1 5. 6 1 0 . 7 1 1 . 2 1 2 . 1 1-18 0.2 0.2 4. 4 1 1 . 8 1 2 . 5 1 1 . 5 0. 1 0. 1 5. 3 1 1 . 2 1 1 . 8 1 1 . 9 1-22 0. 1 0.2 5. o 8.6 1 0 . 8 1 0 . 7 0. 1 0.2 5. & 1 0 . 7 1 1 . 6 1 1 . 4 1-29 0. 1 0. 1 3. 5 5.8 6.3 6 . 3 0. 1 0. 1 4. 0 6.4 6.4 6.4 2 - 0 1 0 . 3 0. 1 3. 4 8. 1 7. 6 8 . 0 0. 1 0. 0 3. 5 6. 1 8. 1 8 . 0 2 - 0 4 0 . 3 0. 1 ji. a & 7.0 7.4 7 . 4 0. 1 0. 1 2. 4 7.4 7 . 9 8.0 2 - 0 8 0.7 0. 0 4. 5 7.8 3 . 3 a . 5 0. 0 0.0 3. 6 7.2 8.3 8.4 NOx-N <mg/L) D A T E " C O N T R O L MODULE E X P E R I M E N T A L MODULE MO-DA AN AX A E 1 A E 2 A E 3 A E 4 AN AX A E 1 A E 2 A E 3 A E 4 2-11 0. 0 0. 0 5. 0 7 . 5 7. 8 7 . 8 0. 0 0. 0 4. 3 7 . £ 7. 8 8. 1 2-18 0. 0 0. 0 4. 7 8. 8. 2 8. 3" 0 . 0 0. 0 5. 1 8 . 6 8. 8 8. 9 0. 0 0. 1 4. 1 3 . 2. 8. 4 8 . 2 0. 0 0. 0 4. 5 3 . 5 8. 6 8 . 6 0. 1 0. 1 4. 9 10. 0 9. 3 10. 0 0. 1 0. 1 5. & 10. 1 10. 1 10. 1 2-29 0. 0 . 1 4. 8 9 . 0 10. 1 10. 1 0. 1 0. 1 5. •71 9 . 8 10. 0 10. 1 3-03 0. 1 0. *H| 4. 8. *J 9 . 4 3 . 5 0. 1 0. 4. 4 8 . 9 9. 5 9 . 5 3 - 1 0 0. 1 0. 1 4 8 . 8 7. 0 7 . 2 0. 1 0. 1 3 . 3 6 . 6 7 . 7 . 4 3 - 1 4 0. 1 0. 1 3 . 6. 7 7 . 4 8 . 0 0. 1 0. 1 9 5 . 8 7. 9 8. 1 3-20 0. 0 . 4 . 3 8. 3 8 . 8 8 . 5 0 . 2 0 . 2 3 . 8 7 . 6 8. 4 8 . 4 DATE CUMULATIVE BODS BODS COD DAY Cmg/L) (mg/L) (mg/L) mo-day un f i11ered f i l t e r e d u n f i l t e r e d 1987 1 8-26 63 114 63 9-04 71 28 27 9-10 77 69 35 9-17 83 79 43 9-22 88 62 23 9-30 96 112 59 385 10-07 103 114 59 275 10-14 1 10 114 57 256 10-21 1 17 120 64 239 10-28 124 114 65 217 11-04 131 128 71 250 11-10 137 112 67 204 11-16 143 119 46 197 11-25 152 105 59 280 12-04 161 131 80 209 12-10 167 110 48 253 12-28 185 101 63 236 12-31 188 77 30 213 1988 1-07 195 68 50 204 1-18 206 60 31 213 1-25 213 45 18 245 1 -30 218 83 48 202 2-08 227 69 48 183 2-12 231 70 40 177 2-15 234 47 24 160 2-13 238 82 51 222 2-22 241 30 45 220 2-26 245 65 35 191 2-29 248 61 34 208 3-04 252 64 41 196 3-07 255 45 14 163 3-08 256 83 50 218 3-15 263 98 .52 213 3-17 265 79 45 214 3 270 70 37 210 273 80 41 195 VFA (mg/L!) DATE " C U M U L A T I V E MO-DAY DAY CONTROL E X P E R I M E N T A L F E E D An An 1987 -6-27 1 0 o 0 7-3 7 0 0 0 7-7 11 0 0 0 7-3 13 0 2.8 1.3 7-13 17 o 1. 1 0 7-20 24 0 1.3 1.5 7-27 31 0 0 0 7-30 34 o 0 0 8-4 33 0 o 0 8-6 41 o 0 o 8-10 45 0 0 0 8-13 48 o 0 0 8-17 52 19.5 12.5 12. 1 8-20 55 0 0 0 8-24 59 0 0 0 8-27 62 0 o 0 8-31 66 0 0 0 9-3 69 0 0 0 9-7 73 0 0 0 9-10 76 0 o 0 3-14 80 o 0 0 9-15 81 4.8 o 0 9-17 83 0 0 0 9-21 87 o o 0 9-28 94 0 0 1. 5 10-8 104 0 0 o 10-15 111 o 0 1. 5 10-19 115 o 0 0 10-22 118 37. 1 0 0 10-26 122 0 o 0 10-29 125 0 0 0 11-9 136 o 0 o 11-12 133 o o 1.3 11-17 144 0 0 •0 11-19 146 0 6.4 6.5 11 -23 150 0 2.8 11-25 152 24. 3 o 0 11 -26 153 0 0 2 • 11 -30 157 0 o 0 12-3 160 0 o 0 12-7 164 o 2. 8 12-3 166 12.4 o 0 12-10 167 3. 1 4. 4 6. 8 12-14 171 0 o 2.7 12-17 174 ^ o o 3.7 12-21 178 0 0 0 12-24 181 0 0 0 12-28 185 0 0 0 12-31 188 0 o 0 VFA Cmq/L ) DATE C U M U L A T I V E MO-DAY DAY 1 9 8 8 1 - 4 1 9 2 1 - 8 1 9 6 1-1 1 1 9 9 1 - 1 4 2 0 2 1 - 1 5 2 0 3 1 - 1 8 2 0 6 1 - 2 0 2 0 8 1 - 2 1 2 0 9 1 - 2 4 2 1 2 1 - 2 5 2 1 3 1 - 2 7 2 1 5 1 - 2 9 2 1 7 2 - 1 2 2 0 2 - 3 2 2 2 2 - 4 2 2 3 2 - 7 2 2 6 2 - 8 2 2 7 2 - 1 1 2 3 0 2 - 1 4 2 3 3 2 - 1 6 2 3 5 2 - 1 7 2 3 6 2 - 1 8 2 3 7 2 - 2 2 2 4 1 . i — ^ J ^.44 2 - 2 7 2 4 6 2 - 2 8 2 4 7 2 - 2 9 2 4 8 3 - 1 2 4 9 3 - 2 2 5 0 3 - 3 2 5 1 3 - 4 2 5 2 3 - 5 2 5 3 3 - 6 2 5 4 3 - 7 2 5 5 3 - 8 2 5 6 3 - 3 2 5 7 3 - 1 0 2 5 8 3 - 1 1 2 5 9 3 - 1 2 2 6 0 3 - 1 3 2 6 1 3 - 1 4 2 6 2 3 - 1 5 2 6 3 3 - 1 6 2 6 4 3 - 1 7 2 6 5 3 - 1 3 2 6 6 3 - 1 3 2 6 7 3 - 2 0 2 6 8 3 - 2 1 2 6 9 3 - 2 2 2 7 0 3 - 2 3 2 7 1 3 - 2 4 2 7 2 CONTROL E X P E R I M E N T A L F E E D An An 8 . 9 0 <-) 2 0 (*) 4 . 5 0 0 0 ("\ 0 o o 1 . 7 7 . 9 0 („) 0 1 . 3 0 1 . 3 1 . 3 o 0 1 . 6 0 0 0 0 1 . 8 0 0 2 • 2 . 1 1 . 2 2 . 9 5 . 2 1 . 2 4 2 . 5 0 2 . 9 5 . 8 o 0 4 . 1 2 . 5 0 0 0 2 . 6 3 . 1 0 0 0 o 1 . 8 1 . 6 0 3 . 1 2 . 4 o 0 9 2 . 1 0 5 . 6 1. 1 4 7 . 1 0 0 0 0 0 6 . 5 2 . 4 1 .1 0 0 1 . 7 0 1 . 5 3 . 4 0 1 . 9 0 0 1. 1 0 0 2 . 2 0 0 3 . 5 0 0 2 . 1 0 0 0 o 0 0 ("\ o o 2 . 2 0 0 2 . 6 o o 2 . 2 0 o •*•> o 0 3 . 7 o 0 3 2 . 4 o 2 . 2 < > • > i 1 . 7 4 . 2 o o 3 3 0 2 . 4 0 o 1 . 4 o o 1 . 5 0 o 0 o 0 2 PERCENT P IN DRY WEIG iHT SLUDGE DATE CUMULATIVE MO-DAY DAY EXPERIMENTAL CONTROL 1387 1 8-04 39 3. 8 3 a & 8-10 45 3.7 3.3 8-13 48 3.4 4.2 8-20 e r r 3.3 3.4 8-24 59 3.7 o z i-f • o 8-31 66 3.7 3.3 9-08 74 4. 1 4. 1 9-14 80 4 3.8 9-21 87 3 • Q 3.3 9-28 94 3.7 3*3 10-08 104 3. 4 3.4 10-15 111 O cr \-f m 3 a & 10-22 118 3.5 3.9 10-29 125 3 • 8 3«8 11-12 133 3.4 3.7 1 1-19 146 3.6 11-26 153 3 a & 3.8 12-03 160 3.4 3.7 12-10 167 12-21 178 3 3 12-31 188 3. 1 3 • S 1938 1-08 196 3.3 3 a 8 1-15 203 2.3 3.7 1-22 210 3. 1 4 1 -29 217 3. 1 4.4 2-04 223 3.2 4.5 2-11 230 3.5 4.8 2-18 237 3 T-" w a X- 4.4 2-25 244 3 ~> 4.5 3-03 251 3.3 4. 1 3-10 258 3.4 4. 1 3-20 263 3.5 4. 1 •*} 270 3.3 273 3. 5 3.7 158 TOC (mg/L) DATE « CONTROL MODULE MC-DA F AN AX AE 1 AE AE3 1987 7-03 i T> 12. C _ l . 4 5. 9 C •_J . 5 6. 4 7-13 22. M 12. 4 8. c ± 8. 5. 3 7-20 24. c 1 0. 5 8. a 7. 0 a •3 6 8-04 ?c 8 13. 1 15. 5 13. 7 1 1 . 8 9. 3 8-17 45. 4 24. 6 12. 7 10. 4 9. 9. —7 / 3-24 19. •—i 13. 6 10. 1 -7 0 8. 1 7. 1 ' 8-31 13. i 12. 3 10. er U 8. 8 g. s 6. 7 9-21 21 . 7 12. 4 1 1 . 1 10. 7. a 7. 9 9-23 13. 0 12. 6 10. 6 8. 3 £. (ii 6. 4 10-08 14. 6 8. w • 3 6. 4 4. 5 3. 9 10-15 m.mi a 1 14. ^ _> 10. 5 8. 4 6. 4 8. 4 10-22 23. 4 23. 4 23. 4 •~»o 4 24. 7 24. 7 10-29 12. 4 6. 2 5. 6 7. 1 4. 5 4. 7 11-12 37. 1 7 16. 0 15. 7 14. 1 14. 1 11-19 28. 7 26. 0 20. 8 13. 1 13. 6 17. 4 11 -26 36« 2 13. 3 14. 8 12. 0 13. 8 10. 6 12-10 41. 3 17. 4 12. 0 10. 3 11. 6 9. 6 12-31 24. *-* wS a 8 16. 5 12. 6 9. 8 8. 6 19S8 1-08 28. 5 23. 1 14. 8 15. 4 15. 11. 6 1-15 30. 3 20. 3 15. 7 15. 4 12. 1 12. 3 1-22 35. 7 17. 3 14. 3 14. 1 13. 9 13. 2 1-29 23. 0 13. 8 18. 0 14. 7 12. *~» w 12. 3 2-04 30. 2 15. 4 14. 12. 0 11. 7 12. 2-11 34. •~t 20. 2 16. 0 16. 7 12. 0 12. 4 2-18 38. 4 22. 3 13. 8 17. 2 15. 4 16. •7.' 2—2 2 31. 6 13. 1 14. A. 10. 5 8.6 10. 8 2-25 35 a 8 20. 0 16. 3 11. 5 12. 8 10.0 3-10 38. 22, 6 16. 5 15. 1 15. 9 12. 1 3-20 37. >~\ 18. 3 14. 2 14. 5 12. 7 13. 0 3-22 31. 3 17. 8 15. 7 11. 7 10. 8 9. 4 3-25 34. 1 16. 3. 0 7. 5 9. 7 6. 9 EXPERIMENTAL MODULE AE4 AN AX AE1 AE2 AE3 AE4 6. a 10. 0 10. 6 ... c 3. 5 3. 0 10. 7 £. 9 13. •7 3. £ — 3 7. T 7. 1 £. 7 6. -71 11 . 3 1 1 . 3 3. 3. 7. 4 5. 4 1 1 . 9 13. 8 1 1 . 4 'Zt ~i —1 2. a. S 8. 2 10. 2 21 . 2 12. 0 9. 4 8. 5 s. 5 7. 9 £. 4 13. £ 10. 1 7. 0 S. 1 7. 1 6. 4 C vJ . 7 12. 4 9. 7 g . £ £. 0 5. £. 0 £. 4 11'. 2 cr 11. 4 9 8. 3 12. £ 7. 1 14. £ 7. 2 8. £. 4. 4 5. 7 6. 0 6. 0 4. 4. 3 2. 4 4. 3 4. •ml 8. 0 16. 8 14. 8. 0 8. a 7. 2 8. 0 3 28. 5 30. 4 26. £ 24. '—1 24. 3 24. 7 4. 1 8. 9 0. 3 3. 5 5 3 4. 0 10. 1 24. 1 18. 3 16. 11. 7 3. 8 10. 1 17. 5 21. 7 15. 2 10. 7 10. 4 11. 7 11 . 5 11. 3 18. 0 14. 8 10. 1 11. 11. 8 10. 1 10. 1 18. 4 14. 1 11. 5 11. 4 11. 1 11 . 0 8. a 19.6 11. 8 8. 3 3. 3 7. 3 8. 2 13. 8 25. 0 15. 5 11. 6 14. 5 11 . 11. 6 10. 6 19. u 15. 5 12. 5 15. 0 14. 7 11. 2 10. 7 20. 5 16. 9 16. 7 11. 5 11. 5 11. 5 11. 5 21. 9 17. £ 15. 0 13. 0 12. 8 12. 7 11. 0 15. 6 13. 1 12. 3 12. 1 3. 1 9. 9 13. 3 23. 0 14. "7-* 12. 12. •ml 10. 5 12. 0 16. 6 25. 5 IS. 7 17. 0 15. 4 15. 3 17. 2 13. 26. 1 13. 9 9. 3 11. S 3. 1 10. 7 12. 1 25. 0 16. 1 9. 4 3. 7 10. 7 9. 8 10. 6 24. 9 18. 6 15. 4 13. 3 12. *-> _J 11 . 0 11. 1 21. 7 15. 5 12. 4 10. 2 10. 1 10. 1 9. 3 19. 1 15. 7 11. 0 8. 3 13. 5 8. 6 6. 8 15. 8 12. 6 8. 5 3. 9 8. 9 7. 8 UNFILTERED COD, TP, TKN IN THE FEED Cmg/L) DATE CUMULATIVE COD TP TKN MO-DAY DAY Cmg/L) (mg/L) (mg/L) 1987 627 1 211 628 629 630 4 701 5 702 6 703 7 145 704 8 705 9 0.8 17 706 10 184 0.9 17.4 707 1 1 156 0.8 17.6 708 12 143 1 17.8 703 13 175 1 17.8 710 14 128 0.9 17.6 71 1 15 131 2.3 17. 1 712 16 134 2.6 17.5 713 17 128 2. 6 17.2 714 18 120 2.4 17.8 715 19 122 2. 7 17.2 716 20 1 15 2.7 17.9 717 3. 1 21.3 718 2.8 20.4 719 3.3 21. 4 720 24 2.8 20. 4 723 27 295 4.3 23. 1 727 31 203 3.8 24. 1 730 34 204 4 21. 3 802 37 296 4.7 24.5 804 39 233 4. 8 25. 2 805 40 210 4.7 25.3 806 41 205 4.3 24. 8 807 42 222 4.5 26. 3 808 43 139 4.4 24.2 809 44 237 4.8 25. 3 810 45 194 4.6 24. 5 811 46 201 4.6 23.8 812 47 184 4.5 20. 6 813 48 195 4.5 21.7 814 49 225 4.3 20. 1 815 50 74 4. 1 19.9 816 51 329 5. 3 27. 3 817 52 155 4.4 23.9 818 53 341 5 • 5 28 819 54 285 5.5 26.7 820 55 243 4 22. 4 UNFILTERED COD, TP , TKN IN THE FEED Cmq/L: DATE CUMULATIVE COD TP TKN MO-DAY DAY (mg/L) (mg/L) (mg/L) ======= =========== ======== ======== : = = = = = = = : S21 56 251 5.3 30. 3 822 57 234 5. 4 30. 6 823 53 210 4.6 27.7 824 53 424 6. 6 33. 7 825 60 259 4.4 25.5 826 61 192 4.2 23.2 827 62 193 4.4 23.5 828 63 237 4.4 23.3 823 64 173 4. 1 22.4 830 65 192 4.3 22. 8 831 66 193 4.5 23. 2 301 67 187 4.2 23.8 302 68 184 4.2 21.6 303 69 195 4.4 23. 9 904 70 184 4. 1 21.6 905 71 184 4.3 22.4 906 72 204 4.4 19. 6 907 73 208 4 19.5 908 74 173 3.8 18.5 909 75 236 4.2 19. 6 910 76 209 3.7 19.5 911 77 211 3.7 18.9 912 78 215 3.6 19.1 913 79 254 4. 1 20. 5 914 30 243 4.2 20.3 915 31 242 3.9 20. 1 916 82 230 3.9 917 83 220 3.9 918 84 215 3.9 20. 1 913 85 212 4.7 20. 7 920 86 210 4.5 24 921 87 210 4. 1 20.9 922 88 211 4.2 20. 8 923 89 195 4. 3 20.6 924 90 212 4.9 21.4 925 91 227 5.6 21 . 6 926 92 219 7.9 21 . 6 927 93 274 4.8 19.8 928 94 410 4.8 20. 8 929 35 435 4.9 21. 6 930 96 335 4.4 20 1001 97 334 3. 9 18. 5 1002 98 237 4.2 17. 1 1003 99 237 4. 3 16.9 1004 100 222 4.5 16.9 1005 101 206 4 15.6 UNFILTERED COD, TP, TKN IN THE FEED Cmq/L) DATE CUMULATIVE COD TP TKN O-DAY DAY Cmg/L) Cmg/L) Cmg/L) 1006 102 217 3.9 15.8 1007 103 275 4 17.5 1008 104 267 5.5 13.2 1009 105 255 7.2 13.5 1010 106 263 6. 1 19.5 1011 107 261 4.9 21 . 8 1012 103 265 6.8 22. 1 1013 103 255 5 21. 2 1014 110 256 3.3 22.6 1015 111 242 3.9 22.3 1016 112 240 3.2 21 .8 1017 113 239 4.8 22 1018 114 246 5.2 22.3 1013 115 254 4.8 22 1020 116 217 4.6 21. 1 1021 117 239 4. 5 22. 4 1022 118 228 4.4 22.5 1023 119 223 4.2 20. 4 1024 120 225 4.3 20. 5 1025 121 224 4.2 22. 4 1026 122 228 5 22. 4 1027 123 226 4.3 21. 3 1028 124 217 4.2 20. 7 1029 125 267 6 28 1030 126 263 4.3 28.4 1031 127 284 4.4 29. 1 1101 128 246 3.3 26.9 1102 129 246 3.9 27. 6 1103 130 224 4.2 27.6 1104 131 250 4 28. 4 1105 132 247 4.7 32.2 1106 133 245 5 32.7 1 107 134 249 4.3 32. 7 1108 135 235 4.9 32. "7 1109 136 228 4.8 32. 3 11 10 137 204 5 32. 3 1111 138 236 5. 1 37. 9 11 12 133 232 5. 1 37. 2 11 13 140 230 5. 1 37 1114 141 1115 142 232 5 37. 5 1116 143 197 5 37. 9 1 1 17 144 253 3.8 19.9 1118 145 264 4 20. 1 1119 146 251 3.8 19.2 1120 147 263 4.5 19.8 UNFILTERED COD, TP , TKN IN THE FEED Cmq/L: DATE CUMULATIVE COD TP TKN MO-DAY DAY Cmg/L) Cmg/L) Cmg/L) 1 121 148 261 1122 143 276 1 123 150 269 1124 151 273 4.5 17.4 1 125 152 280 5. 1 20. 6 1126 153 267 5.2 20. 4 1127 154 235 5.4 20. 7 1128 155 239 5.5 19.2 1123 156 231 5. 1 19. 4 1130 157 255 5.4 19.9 1201 158 235 5.3 19.8 1202 153 239 5. 1 19.8 1203 160 244 5.2 19.9 1204 161 209 4.8 18. 6 1205 162 253 5. 1 21.4 1206 163 265 4.9 20.8 1207 164 215 5. 1 20.8 1208 165 243 5. 3 21.2 1203 166 233 5 20.4 1210 167 253 5. 5 21. 6 1211 168 248 5 21.2 1212 163 269 5.2 20.8 1213 170 266 5. 1 20.8 1214 171 273 5.3 21 1215 172 263 5.2 21.2 1216 173 260 3.3 24 1217 174 331 4. 1 24. 2 1218 175 266 3.7 21.7 1219 176 264 3.7 22 1220 177 257 3.7 21.5 1221 178 264 4.6 21.7 1222 179 257 4.6 21.7 1223 180 250 4.7 21.7 1224 181 262 4.8 21.7 1225 132 255 • 4.5 21 . 7 1226 183 248 3. 9 22 1227 184 241 5. 1 20. 2 1228 185 236 4.5 21 . 2 1223 186 200 4.5 21 . 7 1230 137 208 4.6 22 1231 138 213 4.7 21.7 1988 101 183 217 4.6 23 102 190 208 4.5 20. 6 103 191 208 4.4 20. 6 104 192 217 4.6 22. 4 UNFILTERED COD, TP, TKN IN THE FEED Cmg/L) DATE CUMULATIVE COD TP TKN -DAY DAY (mg/L) Cmg/L) (mg/L) 105 193 223 5. 1 22. 4 106 134 208 4.6 21 . 8 107 135 204 4.5 •-. •-. 103 196 183 4.7 26. 4 103 197 204 4.8 27.6 110 198 210 4.7 28. 4 111 199 213 4.7 28 112 200 206 4.7 27. 8 1 13 201 206 4.7 27.2 114 202 203 5 28. 2 1 15 203 207 4.3 28.4 116 204 145 4.5 25. 6 117 205 193 4.5 27. 6 U S 206 213 4.8 27. 2 113 207 219 4.9 28.6 120 208 207 4.9 26. 6 121 209 193 4.8 27.8 122 210 201 4.5 21. 1 123 211 187 4.5 19.2 124 212 215 4.5 19.8 125 213 245 4.6 19.4 126 214 176 4 17.7 127 215 180 4.5 17.6 123 216 224 4.5 17. 6 129 217 214 4.9 20. 9 130 218 202 4.9 20.9 131 219 204 4.8 21.3 201 220 298 4.7 •-.>•-< 202 221 210 5 22.2 203 222 204 4.5 22. 4 204 223 201 4.5 23. 1 205 224 191 4.5 22.7 206 225 186 4.6 22.3 207 226 195 4.4 21 .-3 208 227 189 4.6 21.1 209 228 184 4.4 20. 8 210 223 182 4.4 21.4 211 230 187 4.6 21. 6 212 231 177 4.4 20. 5 213 .2 160 4.3 20. 3 214 164 4.3 20.7 215 234 160 4.2 21 . 5 216 235 233 4.9 24.6 217 236 233 4.9 24. 1 218 *j i 215 4.9 24.4 213 4.8 23. 7 UNFILTERED COD, TP, TKN IN THE FEED <mq/L:> DATE CUMULATIVE COD TP TKN O-DAY DAY Cmg/L:> (mg/L) Cmg/L:> 220 239 207 4.6 23. 2 221 240 218 4.6 23. 2 241 220 4.7 24.6 223 242 139 4.7 24. 6 224 243 207 4.7 24.6 225 244 193 4.7 27. 8 226 245 131 4.9 24.8 227 246 183 4.9 25.2 228 247 200 5. 1 25.8 229 248 208 5.6 25.2 301 249 181 5. 1 25.8 302 250 198 5 25. 6 303 251 182 4.9 25.2 304 252 196 305 253 178 5 26.6 306 254 163 5 25. 9 307 255 163 308 256 218 5 22.3 303 257 216 5 33. 3 310 258 222 5. 1 23. 1 311 259 216 5 22.6 312 260 224 5. 1 23.7 313 261 218 5 23 314 252 210 5. 1 23.5 315 263 213 5. 1 23. 1 316 264 ??•? 4.9 22 . 317 265 214 4.9 21.9 318 266 189 4.9 21. 5 313 267 205 4.9 21.9 32Q 268 203 4.6 23 321 263 205 4.7 22.6 322 270 210 4.7 22. 6 323 271 216 4.8 24. 1 324 272 203 4.8 23.5 325 273 195 4.8 22.8 165 NOx-N Cmg/L > B A T C H T E S T S C U M U L A T I V E B A T C H T E S T 1 B A T C H T E S T 2 R E P E A T T I M E (min'.) E X P E R I M E N T A L C O N T R O L E X P E R I M E N T A L CONTROL C 0 N T R 0 L - 3 0 3 . 0 7 3. 0 7 2. 7 5 2. 4 7 2 . 8 9 5 2 . 7 7 2. 9 4 2.4 2. 7 2 10 2. S 3 2. 7 9 2 . 1 4 2. 02 2 . 4 15 2. 4 4 2 . 5 6 1.91 1.35 2. 14 3 0 1.91 1.97 1. 19 1.3 1 .32 4 5 1.34 1 .52 0. 4 9 0 . 3 6 1. 16 £ 0 0. 8 7 0 . 8 9 0. 0 5 0. 5 6 0. 0 3 7 5 0. 3 7 0 . 6 1 0. 0 6 0 . 0 4 9 0 0 . 0 6 0 . 1 1 0. 0 5 0 . 2 5 0. 0 5 120 0. 0 6 0. 0 4 P 0 4 - P Cmg/L) B A T C H \ T E S T S C U M U L A T I V E B A T C H T E S T 1 B A T C H T E S T 2 R E P E A T T I M E E X P E R I M E N T A L C O N T R O L E X P E R I M E N T A L CONTROL C 0 N T R 0 L - 3 0 5 . 9 3 8. 2 6 7 . 0 7 8.61 8 . 3 3 5 5. 9 8 * 3 7. 0 4 9. 11 8 . 3 6 10 5. 7 7 8 . 0 8 6 . 3 3 3 . 6 4 8. 18 15 5. £ 4 7 . 7 9 6 . 7 9 8.7 3. 0 3 3 0 5. 4 4 7 . 5 6 6. 3 3 8.3 7. 6 2 4 5 . 5. 1 7 . 3 1 5. 9 6 7 . 2 2 7. 19 £ 0 4 . 8 1 6. 6 7 5. 6 5 6. 7 3 7. 0 4 . 7 5 4 . 5 9 6. 4 4 5 . 9 9 6. 0 5 7 . 4 7 9 0 4. 4 6 5 . 9 2 6 . 2 7 5 . 2 5 8 . 0 3 120 5 . 0 6 5 . 7 7 PHA AS PHB Cmg/L) B A T C H T E S T S C U M U L A T I V E B A T C H T E S T 1 B A T C H T E S T 2 R E P E A T T I M E ( m i n ) E X P E R I M E N T A L C O N T R O L E X P E R I M E N T A L C O N T R O L C 0 N T R 0 L - 3 0 1 2 . 9 14 1 3 . 6 1 4 . 7 1 2 . 4 5 12 1 3 . 7 1 3 . 8 1 4 . 6 1 5 . 7 10 12. 1 1 2 . 7 1 3 . 3 1 4 . 5 14 15 1 1 . 2 1 2 . 6 1 2 . 6 1 5 . 1 1 3 . 9 3 0 1 0 . 7 13 1 1 . 4 1 2 . 5 1 1 . 7 4 5 1 0 . 4 1 1 . 5 12.-1 1 3 . 4 1 2 . 6 £ 0 1 0 . 3 1 1 . 7 1 0 . 5 1 2 . 4 1 1 . 6 7 5 1 0 . 4 1 0 . 8 1 0 . 4 1 1 . 7 13 9 0 10 11 1 0 . 4 1 0 . 6 1 2 . 1 1 2 0 1 0 . 9 1 0 . 9

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