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Laboratory study on aerated stabilization basin operation at 3°C Atwater, James Wesley 1973

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A LABORATORY STUDY ON AERATED STABILIZATION BASIN OPERATION AT 3°C  by  JAMES WESLEY ATWATER B.A.Sc, University of B r i t i s h Columbia, 1969  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE  i n the Department of C i v i l Engineering  We accept t h i s thesis as conforming to the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA September, 1973  In p r e s e n t i n g an  advanced  the  Library  I further for  this thesis  degree at shall  the  of  this thesis  written  representatives.  of  be  for  Civil  Engineering  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, C a n a d a  1973  Columbia  shall  the  not  the  requirements  Columbia,  for reference  Head o f my  be  I agree and  copying of  It i s understood"that  for f i n a n c i a l gain  October 9,  British  extensive  g r a n t e d by  permission.  Department o f  Date  University  permission  s c h o l a r l y p u r p o s e s may his  f u l f i l m e n t of  make i t f r e e l y a v a i l a b l e  agree that  by  in partial  that  study.  this  thesis  Department  copying or  for  or  publication  allowed without  my  A B S T R A C T  Aerated s t a b i l i z a t i o n basins (ASB), l i k e many other b i o l o g i c a l t r e a t ment systems, demonstrate a temperature dependency.  A decrease i n treatment  e f f i c i e n c y usually r e s u l t s from a decreasing basin temperature and has often been related to a decrease i n the reaction rate c o e f f i c i e n t , K.  This r e l a t i o n -  ship to the reaction rate may well apply f o r other treatment systems, but i t has not been c l e a r l y demonstrated f o r aerated s t a b i l i z a t i o n basins.  This study develops data on steady-state performance at 3 C i n order to present a coherent reference point f o r future ASB temperature studies and to define performance c h a r a c t e r i s t i c s at 3°C. The following performance c r i t e r i a were documented i n the study: 1. Substrate removal i n terms of f i l t e r e d substrate removal. (61 - 80 per cent COD removal and 76 98 per cent BOD^ removal f o r retention times of 1 - 16 days).  2. System treatment e f f i c i e n c y defined i n terms of gross e f f l u e n t COD and B0D . (23 - 50 per cent COD removal and 18 - 80 per cent BOD^ removal f o r retention times of 1 - 16 days). 5  BOD  3. Net b i o l o g i c a l s o l i d s production (0.25 l b s / l b or COD used).  4. Oxygen u t i l i z a t i o n requirements (0.123 l b s O2/ l b COD removed and 0.143 l b s 0 /B0D^ removed f o r retention times of 2 - 16 days. Endogenous r e s p i r a t i o n - 0.75 mg/hr/ gm MLSS). 2  5. Nitrogen transformation. (A transformation of Kjeldahl nitrogen i n the b i o l o g i c a l s o l i d s to NH^ n i t r o gen i n the f i l t r a t e was found apparently as a function of retention time). ii  iii  6.. Post S e t t l i n g . (One day's aeration with one day s e t t l i n g was found to give equivalent treatment as eight days aeration and one day s e t t l i n g ) .  Data was obtained at two loadings to provide information on the influence of i n f l u e n t concentration on o v e r a l l performance. Established i n the experiment was that any of the common mathemat i c a l models used to describe ASB operation, McKinney's, Eckenfelder's, or f i r s t - o r d e r exponential, could predict system treatment e f f i c i e n c y at 3°C for r e t e n t i o n times beyond two to four days.  It was further shown that only  the Chemostat model would describe the substrate removal measured i n the study.  TABLE OF CONTENTS Page  LIST OF TABLES  vii  LIST OF FIGURES  viii  LIST OF TERMS  x  CHAPTER I.  II.  INTRODUCTION  1  1.1 1.2  1 2  LITERATURE SURVEY II. 1 11.2 11.3 11.4 11.5 11.6  III.  GENERAL. RESEARCH OBJECTIVES  3  GENERAL DESIGN FORMULATIONS FOR SUBSTRATE REMOVAL IN ASBs . . . TEMPERATURE COMPENSATION IN DESIGN FORMULATION TREATMENT EFFICIENCY. . . SOLIDS PRODUCTION AND SETTLING NUTRIENT REQUIREMENTS . . . . .  3 3 8 10 11 12  RESEARCH METHODOLOGY  14  111.1 111.2 111.3 111.4 111.5  14 17 18 20 23  RATIONALE GENERAL PROCEDURE EQUIPMENT AND FLOW . . . SUBSTRATE. . . ANALYTICAL PROCEDURES  iv  V  CHAPTER  IV.  .Page  RESULTS AND DISCUSSION  26  IV. 1 IV.2  GENERAL CRITERIA FOR STEADY STATE OPERATION  26 26  IV.2.1 IV.2.2  26 27  IV.3  PER CENT SUBSTRATE REMOVAL AND SYSTEM TREATMENT EFFICIENCY. IV.3.1 IV.3.2  IV.4  IV.4.3 IV.4.4 IV,A.5  V.  50  Solids Production COD - B0D of ASB Solids S e t t l i n g at 3°C 5  50 53 56  NITROGEN STUDIES  61  IV.6.1 IV.6.2 IV.6.3  61 61 62  General Nitrate Nitrogen Nitrogen Balance  pH  65  IV.8  OXYGEN UTILIZATION  65  SUMMARY  V.3 V.4 V.5 V.6 V.7  VII.  General 36 Evaluation of O'Connor and Eckenfelder's Models . . . 36 McKinney's Model. 41 Chemostat 44 First-Order Exponential 46  IV. 7  V.l V.2  VI.  Per Cent Substrate Removal (Substrate U t i l i z a t i o n ) . . . . 32 System Treatment E f f i c i e n c y 34  ASB SOLIDS IV.5.1 IV.5.2 IV.5.3  IV.6  32  EVALUATION OF MATHEMATICAL MODELS USED IN ASB DESIGN. . 36 IV.4.1 IV.4.2  IV.5  Low Loading Study High Loading Study  70  STEADY STATE ; . . . . 70 PER CENT SUBSTRATE REMOVAL AND SYSTEM TREATMENT EFFICIENCY 70 MODEL EVALUATION 71 SOLIDS PRODUCTION 71 NITROGEN USAGE 72 pH -; 72 OXYGEN UPTAKE 72  CONCLUSIONS  74  RECOMMENDAT IONS  77  vi  Page  BIBLIOGRAPHY  .79  APPENDIX A EXPERIMENTAL DATA  84  APPENDIX B TEST DATA PERTAINING TO THE DETERMINATION OF .STEADY STATE OPERATION - LOW LOADING  98  APPENDIX C CALCULATION OF CONSTANTS AND BOD CONCENTRATIONS McKINNEY' S MODEL 5  .100  LIST OF TABLES  Table 1.  Page TEMPERATURE COEFFICIENTS FOR BIOLOGICAL TREATMENT SYSTEMS  9  2.  REACTION HYDRAULIC RETENTION TIME  3.  ANALYSIS OF POWDERED MILK WASTE  21  4.  GREATER VANCOUVER WATER DISTRICT PHYSICAL AND CHEMICAL ANALYSIS OF WATER SUPPLIES  22  MEASURED AND CALCULATED SYSTEM TREATMENT EFFICIENCIES, O'CONNOR AND ECKENFELDER'S MODEL  40  MEASURED AND CALCULATED SUBSTRATE CONCENTRATIONS, McKINNEY'S MODEL  42  MEASURED AND CALCULATED GROSS EFFLUENT BOD McKINNEY'S MODEL •  43  5. 6.  7. 8. 9.  .  5  20  CONCENTRATIONS,'  MEASURED AND CALCULATED SYSTEM TREATMENT EFFICIENCY, FIRST-ORDER EXPONENTIAL  '49  NET SOLIDS PRODUCTION PER POUND SUBSTRATE REMOVED  52  10.  EFFLUENT CHARACTERISTICS OF ASBs AT 3°C  54  11.  GROSS KJELDAHL NITROGEN CONCENTRATIONS  63  12.  AVERAGE NITROGEN CONCENTRATIONS —  63  vii  LOW LOADING  LIST OF FIGURES  Figure  Page  1.  SCHEMATIC OF MODEL ASB  2.  STEADY STATE - 16 DAY REACTOR - LOW LOADING  28  3.  CYCLIC FLUCTUATIONS OF FILTERED COD CONCENTRATIONS  29  4.  HYDRAULIC EQUILIBRIUM - HIGH LOADING  30  5.  STEADY STATE - SYSTEM TREATMENT EFFICIENCY COD - HIGH LOADING.31  6.  PER CENT SUBSTRATE REMOVAL AS A FUNCTION OF MEAN HYDRAULIC RETENTION TIME AT 3°C  33  SYSTEM TREATMENT EFFICIENCY AS A FUNCTION OF MEAN HYDRAULIC RETENTION TIME  35  EVALUATION OF REACTION RATE CONSTANT (K) FOR SUBSTRATE REMOVAL (Se) (O'CONNOR AND ECKENFELDER)  37  7. 8. 9.  .18  EVALUATION OF REACTION RATE CONSTANT (K) FOR SYSTEM • TREATMENT EFFICIENCY AT 3°C (O'CONNOR AND ECKENFELDER). . . . 39  10.  CHEMOSTAT FIT - COD SUBSTRATE CONCENTRATION  "11.  EVALUATION OF REACTION RATE CONSTANT K FOR  12.  SUBSTRATE REMOVAL AT 3°C EVALUATION OF REACTION RATE CONSTANT K FOR SYSTEM TREATMENT EFFICIENCY  13.  MIXED LIQUOR SUSPENDED SOLIDS AS A FUNCTION OF MEAN HYDRAULIC RETENTION TIME AT 3°C  45  47 48 51  14.  PER CENT COD REMOVAL WITH SETTLING TIME - 3°C - LOW LOADING . 57  15.  PER CENT COD REMOVAL WITH SETTLING TIME - HIGH LOADING. . . . 58  16.  SUPERNATANT MLSS v s . SETTLING TIME - 3°C - HIGH LOADING . . . 60  17.  CONCENTRATIONS OF NITROGEN COMPOUNDS IN THE REACTOR SOLIDS AND FILTRATE AS A FUNCTION OF MEAN HYDRAULIC RETENTION TIME HIGH LOADING  viii  64  ix  /  •  Figure  Page  18.  OXYGEN UPTAKE AGAINST RETENTION TIME  66  19.  OXYGEN CONSUMPTION PER DAY AS A FUNCTION OF SUBSTRATE REMOVED PER DAY - HIGH LOADING  68  OXYGEN UPTAKE RATE AS A FUNCTION OF REACTOR SUBSTRATE CONCENTRATION  69  20.  LIST OF TERMS  ASB  - Aerated  BOD,  - 5 day Biochemical  BOD  - Ultimate  Biochemical  COD  - Chemical  Oxygen Demand  MEAN HYDRAULIC RETENTION TIME  MLSS  Stabilization  Basin  Oxygen Demand  Oxygen Demand  Theoretical retention time of any given particle; equal to the reactor volume divided by the mean flow rate.  - Mixed  Liquor  Suspended  Solids  NUTRIENTS  Elements in addition to carbon necessary for b i o l o g i c a l growth; usually refers, but not restricted, to nitrogen arid phosphorus.  PER CENT SUBSTRATE REMOVAL  Percentage decrease in applied measured between the influent effluent.  STEADY STATE  Condition existing there is hydraulic  SYSTEM TREATMENT EFFICIENCY  Per cent reduction in COD or BOD measured between the influent and effluent; r e f l e c t s the COD or BODr of generated solids in the effluent.  vss  substrate and the  in the reactors when and b i o l o g i c a l equilibrium.  5  - Volatile x  Suspended  Solids  A C K N O W L E D G M E N T  The author wishes to express h i s thanks and appreciation to h i s supervisor, Dr. A. H. Benedict, f o r h i s guidance, enthusiasm and patience during the preparation and completion of t h i s study.  The author  also wishes to thank h i s wife, Cheryl, and Dr. R. D. Cameron, L i z a McDonald, Murray Hendren and Dale Wetter f o r their help and assistance. This study was financed through National Research Council Grant, NRC 67-8253.  xi  CHAPTER I INTRODUCTION  1.1  GENERAL The aerated s t a b i l i z a t i o n basin (ASB) as a means of waste t r e a t -  ment was  i n i t i a l l y developed  from the upgrading of waste water holding ponds.  Today, however, the ASB treatment system i s recognized as having a b i o l o g i c a l basis.  Unlike other b i o l o g i c a l treatment  systems, ASBs do not have the com-  p l e x i t i e s of sludge recycle, which makes them i d e a l systems f o r r u r a l indust r i e s and communities where land i s cheap and operational supervision and a v a i l a b l e c a p i t a l are minimal. Included among the many users of ASBs are numerous communities and industries located i n northern areas where severe winter conditions are encountered.  ASBs operated i n these northern areas have been successful, but  they have invariably demonstrated a change i n treatment e f f i c i e n c y with a change i n basin temperature.  It i s t h i s change which requires investigation.  Descriptions of lagoons and basins, aerated lagoons, aerobic lagoons, f a c u l a t i v e lagoons, oxidation ditches, photosynthetic ponds, and aerated stabi l i z a t i o n basins can be found throughout  the current l i t e r a t u r e .  Unfortunately,  one man's photosynthetic pond has often turned out to be another man's aerated lagoon.  Therefore, i n an attempt to avoid any semantic d i f f i c u l t i e s ,  treatment system described i n t h i s paper, modelled  the  i n the laboratory and  c a l l e d an aerated s t a b i l i z a t i o n basin has the following c h a r a c t e r i s t i c s :  2  1. The basin i s h y d r a u l i c a l l y completely mixed, with the mean hydraulic retention time equal to the mean c e l l residence time (sludge age). 2. the system.  There i s no sludge recycle incorporated into  3. The chemical and b i o l o g i c a l oxygen requirements of the treatment process are s a t i s f i e d by mechanical means — generally, surface aerators, or d i f f u s e r systems. 4. T h e o r e t i c a l l y , there i s s u f f i c i e n t energy within the basin to maintain a l l the s o l i d s i n suspension. Solids loss occurs only through oxidation or effluent carry-over.  1.2  RESEARCH OBJECTIVES The p r i n c i p l e objective of this study was to obtain data on the  operation of laboratory-scale ASBs at a low operation temperature (3°C), and to analyze the performance of these systems i n terms of existing mathematical models used to describe ASB operation. f i v e operating parameters was c o l l e c t e d :  To do t h i s , information on  substrate u t i l i z a t i o n , system t r e a t -  ment e f f i c i e n c y , s o l i d s production, nitrogen transformations and oxygen uptake. Of these-, the f i r s t two were used to evaluate the performance of the laboratory ASBs i n terms of the existing mathematical models, while the other data were used to define performance c h a r a c t e r i s t i c s .  In addition information on the  s e t t l i n g c h a r a c t e r i s t i c s of ASB effluent a t 3°C was c o l l e c t e d .  CHAPTER II  LITERATURE SURVEY  11.1  GENERAL The aerated s t a b i l i z a t i o n basin i s a recent innovation i n the  treatment of waste water, having only come into prominence since the early 1960s.  It was  not u n t i l 1959  that turbine aerators were used (21).  Since  t h e i r inception ASBs have been used with some success i n northern climates, even though treatment  e f f i c i e n c y reportedly decreases during the winter  months (34) (42)(43).  Today, the ASB i s used f o r treating wastes throughout  the i n d u s t r i a l segment, from food processing to petrochemical wastes (18).  (14)  Besselievre (4) presents an extensive l i s t of references for i n d u s t r i a l  waste applications of ASB systems.  11.2  DESIGN FORMULATIONS FOR SUBSTRATE REMOVAL IN ASBs Many of the ASBs now  i n operation developed  from overloaded photo-  synthetic or f a c u l t a t i v e lagoons which were modified through the i n s t a l l a t i o n of aeration equipment (23)(36).  Other basins have been designed empirically 2  using loading guidelines such as 1.7-2.3 lbs BOD/day/1000 f t . , 700  people/  day/acre, or 2000 lbs BOD /acre/day f o r 10 foot depth (16)(8)(28).  Today  5  most ASB design manuals (19) (11) follow one or two design models. The f i r s t design model was developed by O'Connor and (30).  Eckenfelder  For t h i s model substrate removal i n a completely mixed basin i s  described by the following equation:  where S  E  = effluent substrate concentration, mg/l;  S  q  = influent substrate concentration, mg/l;  K  = reaction rate c o e f f i c i e n t , day ^;  t  = mean hydraulic retention time, days.  and  equation  Equilibrium v o l a t i l e solids i n the ASB are described by the  S  + aS  where X  v  = v o l a t i l e s o l i d s , mg/l;  Q  = v o l a t i l e s o l i d s i n influent waste, mg/l;  S a S  = y i e l d factor, mg v o l a t i l e s o l i d s produced/mg substrate used; r  = substrate u t i l i z e d , mg/l;  b  = endogenous c o e f f i c i e n t , % loss/mg v o l a t i l e s o l i d s ;  t  = mean hydraulic retention time, days.  and  In a completely mixed ASB mean hydraulic retention time (basin volume/flow), t , i s equal to the treatment time and the concentration of reactants i n the effluent i s the same as the concentration i n the basin. For a given waste and required soluble effluent concentration the mean hydraulic retention time, t, and therefore the basin size, can be calculated.  5  A second design model has been developed by McKinney (19). Unl i k e O'Connor and Eckehfelder, who assume a pseudo f i r s t - o r d e r substrate removal, McKinney assumes that a l l available BOD i s metabolized i n the f i r s t twenty-four hours.  He further assumes that the remaining treatment  time i s used for oxidizing the b i o l o g i c a l solids produced i n u t i l i z i n g the substrate.  The following three equations form the basis of McKinney's  model:  F =  k t  (3)  + 1  5  k,F M  =  2  (4)  a  1/t + K-  e  = F + k M 10 a  and F  (5)  where F = unmetabolized waste B0D^,mg/l; F  ±  - i n f l u e n t waste B0D , mg/l;  k  5  = metabolism constant, 120 d a y  5  - 1  at 5°C to 720 d a y  - 1  at 30°C;  1  at 30°C;  t = mean hydraulic retention time, days; M  = active microbial mass, mg/l; cl  k  6  k  7  = synthesis constant, 83 d a y s  at 5°C to 500 days"  = endogenous metabolism c o e f f i c i e n t , 0.16 days at 5°C to 0.48 d a y s at 20°C f o r t < 5 days and 0.04 d a y at 5°C to 0.12 at 20°C f o r t >_ 20 days; 1  - 1  F  -1  e  = effluent B0D  5>  - 1  mg/l;  and k^Q =  BOD5  p r o p o r t i o n a l i t y constant, M).6 dimensionless.  6  For a given input waste loading and effluent requirement the retention time, t, i s calculated on a t r i a l and error basis. In addition to the two models described above, three other models have been developed to describe ASB operation; these are the Chemostat Model, the f i r s t - o r d e r exponential, and a specialized model f o r pulp and paper wastes. The Chemostat i s a name coined by Novick and S z i l a r d (30) f o r a single, homogeneous, completely reactor; an ASB.  s t i r r e d , constant volume, flow through  The equation describing the substrate remaining  Chemostat i s the steady-state s o l u t i o n of two equations:  i n the  the Monod formu-  l a t i o n , describing substrate oxidation k i n e t i c s , and a d i f f e r e n t i a l describing reactor hydraulics.  equation  The Chemostat model i s given by the equation  K (D) m where S = substrate concentration i n the reactor, mg/l; K u  = a saturation constant, mg/l (numerically equal to substrate concentration when u = %umax.), ( u = growth rate); m  = maximum growth rate constant, days ^;  and D = d i l u t i o n rate, days  1  (reciprocal of hydraulic retention time).  The Chemostat Model has not been widely applied to waste treatment systems, although some applications are a v a i l a b l e . The fourth model, the f i r s t - o r d e r exponential, i s described by the equation S/S = " e o e  k t  (7)  7  where S  G  = e f f l u e n t substrate concentration, mg/l;  S  q  = i n f l u e n t substrate concentration, mg/l;  k  = reaction rate c o e f f i c i e n t , days ^;  t  = mean hydraulic retention time, days.  and  The f i r s t - o r d e r exponential model i s often presented by Eckenfelder (10), but the h i s t o r y or reasoning behind t h i s equation i s unknown. be s t r i c t l y based on empirical  I t appears to  criteria.  The f i f t h mathematical model i s described by the following equations (13): L/L  Q  = (1 + 0 . 5 5 t ) "  for no nutrient addition; and L/L  Q  = (1 + 0 . 9 5 t ) ~  (8)  0 , 7 8  > 1 , 0 5  (9)  for nutrient addition, where L = effluent B0D L  Q  5>  mg/l;  = i n f l u e n t B0D , mg/l; 5  and t = hydraulic retention time, days. This model was developed to describe the treatment of mixed pulp and paper wastes i n ASBs, and i t s use i s therefore r e s t r i c t e d to the pulp and paper industry.  The c o e f f i c i e n t s were empirically derived.  8  II.3  TEMPERATURE COMPENSATION IN DESIGN FORMULATIONS  The temperature dependency of b i o l o g i c a l systems has been reported by numerous authors  (7) (9) (25) (32).  O'Connor and Eckenfelder (31)  decrease the reaction rate constant i n t h e i r design model i n order to compensate f o r a temperature drop.  This decrease i n the reaction rate constant,  K, i s related to the drop i n temperature by the modified Van't Hoff-Arrhenius equation: K_  = K_  R  1  • 0 1' R T  (10)  T  l  where YL,  = reaction rate constant, days ^ (at temperature T.°C); -  l  l  l  K_ = reaction rate constant, days R T  1  (at a reference temperature, normally 20°C);  0 = temperature c o e f f i c i e n t , theta, dimensionless; T, = ASB temperature, °C; and T  R p  = reference temperature, °C.  The temperature c o e f f i c i e n t , 0, i s a measure of the s e n s i t i v i t y of a system to temperature change.  Reported values of 0 vary from 1.0 to 1.13, depending  on the system i n question. (7)(9)(37)(42).  The commonly accepted 0 value f o r ASBs i s 1.035  Table 1 shows a number of the reported 0 values f o r ASBs.  Commonly assumed values f o r several other b i o l o g i c a l treatment systems are also shown (7)(9)(37).  9  TABLE 1 TEMPERATURE COEFFICIENTS FOR BIOLOGICAL TREATMENT SYSTEMS  P R 0 C E S S  TEMPERATURE RANGE  0  WASTE  ASB  1.035  10-30°C  Cotton t e x t i l e  ASB  1.046  13-20°C  Domestic sewage  ASB  1.026  2-10°C  Pulp and paper  ASB  1.058  10-30°C  Pulp and paper  ASB  1.16  4-20°C  S t a b i l i z a t i o n ponds  1.072-1.085  3-35°C  Activated sludge  1.0  4-45°C  Trickling  1.035  filter  -1.041  Aerobic-facultative lagoon  1.06-1.18  Extended aeration  1.037  McKinney compensates  F r u i t processing  10-35°C 4-30°C 10-30°C  for temperature changes by varying three of the four  constants, K^, K^ and K^, used i n h i s design equations. He assumes that the fourth constant, K^Q (the r a t i o of BOD^ to unit weight of active solids generated), remains constant with temperature at ^0.6. No information was found on temperature compensation for the Chemostat or f i r s t - o r d e r exponential models, although f o r the l a t t e r i t i s assumed that the ©-concept can be applied to the reaction rate c o e f f i c i e n t , k.  10  Eckenfelder (10) developed the following equation f o r p r e d i c t i n g the temperature of ASB contents i n terms of ambient a i r temperature, i n fluent temperature, flow and expected heat l o s s : (T T  i -  T  w  =  W  - T )fA Q  <>  3  n  where T^ = influent temperature, °F; T  w  = mean basin temperature, °F;  T  = mean a i r temperature, °F;  A  = basin area, square feet,  Q  = waste flow, U.S. mgd;  f  = proportionality factor accounting f o r heat transfer, surface turbulence, wind and humidity effects (for central United States, f = 12 x 10~ ) (mgd/ft ).  and  2  This equation i s widely accepted i n industry and has been reported to give excellent r e s u l t s (3)(19)(42).  II.4  TREATMENT EFFICIENCY Treatment e f f i c i e n c i e s have been reported f o r a number of f i e l d and  laboratory ASBs operating at cold temperatures and over a range of temperatures. Carpenter, et al. (7) studying f i v e d i f f e r e n t pulp and paper wastes at retention times of 2.5, 5 and 10 days and temperatures of 2°C, 10°C, 20°C and 30°C, found that treatment e f f i c i e n c y i n the 2.5 day reactor increased from 56% at 2°C to 79% at 30°C, while i n the ten day reactor treatment e f f i c i e n c y increased from 79% at 2°C to 88% at 30°C.  Thus, the o v e r a l l  e f f e c t of temperature on treatment e f f i c i e n c y was shown to decrease with an  11  increase i n retention time.  Ling (24), studying the treatment of chemi-  c a l wastes i n aerated lagoons, also reported a s i g n i f i c a n t e f f e c t of temperature on treatment e f f i c i e n c y which was  lessened with increasing reten-  t i o n time. Timpany, et al.  (42), studying three f u l l - s c a l e , five-day aerated  lagoons t r e a t i n g pulp and paper wastes i n northern B r i t i s h Columbia and Alberta, found that treatment e f f i c i e n c y increased 20% for an increase of 10°C i n the 14°C to 30°C range. Bartsch and Randall (3), reporting on the state of the a r t , showed that for a five-day aerated lagoon system, where some s e t t l i n g occurring, 14.4°C was a c r i t i c a l temperature as treatment e f f i c i e n c y  was de-  creased markedly from 90% at 14.4°C to 55% at 5°C. Esvelt, et al.  (14) reported treatment e f f i c i e n c i e s for apple  processing waste of 84 to 88% at 4-7 C with a retention time of ten to eleven days.  Reid (34), studying a basin t r e a t i n g domestic sewage i n  Alaska, reported that treatment e f f i c i e n c y remained above 80% even though temperatures were near-freezing.  Goodrow (20) reported s i m i l a r results at  Regina, Saskatchewan when the treatment basin had an ice-cover.  II.5  SOLIDS PRODUCTION AND  SETTLING  L i t e r a t u r e d i r e c t l y pertaining to net s o l i d s production i n ASBs at cold temperatures i s almost non-existent. genous oxidation rate to be decreased al.  Goodman (19) shows the endo-  at low temperature, as do Esvelt, et  (14); however, most of the information a v a i l a b l e i s general or refers  to elevated temperatures.  Eckenfelder  solids concentration i n an ASB  (10) maintains  that the equilibrium  from a soluble feed w i l l be 50% of the influent  12  BOD concentration.  Gellman (17), c i t i n g a number of pulp and paper, p i l o t  studies at 25-35°C, found that sludge accumulated at a rate of 0.15 to 0.30 pounds per pound of BOD removed, i t i s not clear from Gellman's paper, or from the p i l o t studies c i t e d , whether or not these figures r e f e r s p e c i f i c a l l y to net s o l i d s production. Reported values of BOD associated with the b i o - s o l i d s i n ASBs are also of a general nature.  Eckenfelder (10) graphs the BOD of the v o l a t i l e  s o l i d s vs. sludge age and shows mg of BOD per mg of v o l a t i l e s o l i d s of 0.75 to 0.3 for sludge ages of 0 to 7 days.  Goodman (19) shows the BOD per unit  of a c t i v e s o l i d s to be 0.6, regardless of sludge age or temperature.  Gellman  (17), again c i t i n g a number of pulp and paper p i l o t studies at 25-35°C, r e ports that the s o l i d s were well s t a b i l i z e d and the BOD per u n i t of s o l i d s was 0.1 to 0.2 pounds per pound f o r retention times of four to twenty days.  How-  ever, i t was not clear whether or not influent s o l i d s were included i n the measurements. Secondary s e t t l i n g or polishing ponds are commonly used to improve the solids quality of ASB e f f l u e n t s (17)(23)(36), and t h i s i n turn provides some improvement i n the o v e r a l l BOD removal. ported improvements  For pulp and paper wastes r e -  i n BOD removal vary with s e t t l i n g from 2-15% for aeration  times of two to ten days (1)(7)(35)(46).  II.6  NUTRIENT REQUIREMENTS McKinney  (27), discussing b a c t e r i a l synthesis, shows the nitrogen  and phosphorus requirements to be 11% and 2.5% of the dry weight of the bacteri a l c e l l or, expressed  as a carbon:nitrogen:phosphorus r a t i o , 20:4.4:1.  Eckenfelder (10) describes nutrient requirements i n b i o l o g i c a l treatment  13  systems i n terms of the v o l a t i l e solids concentration by the following two empirical  equations:  Nitrogen  (N) = 0.12 AX + 1.0 mg/l  (12)  V  Phosphorus (P) = 0.02 AXv + 0.5 mg/l  *  (13)  where AXv = change i n v o l a t i l e s o l i d s concentration, mg/l. Esvelt et al.  (14) found that nutrient requirements f o r f r u i t pro-  cessing wastes were a function of BOD concentration and the removal rate constant, k.  This r e l a t i o n s h i p was expressed by the two empirical  equations:  N/BOD ' = 0.087 BOD - 0.80 x 0.087k removed cone  (14)  P/BOD . = 0.016 BOD - 0.80 x 0.016k removed cone  (15)  where N/B0D  remQve(  j  = lbs nitrogen required/lb BOD removed;  P/B0D  r e m o v e <  j  = lbs phosphorus required/lb BOD removed;  k  = removal rate constant  (0.115 at 20°C).  These authors also indicate that temperature had an effect on the nutrient requirements i n ASBs. In the pulp and paper industry, the usual practice has been to describe nutrient requirements i n terms of the BOD applied or removed.  Ecken-  felder (13) reports that for pulp and paper wastes optimum treatment should r e s u l t from nutrient a v a i l a b i l i t y of 4.0 lbs of nitrogen and 0.6 lbs of phosphorus per 100 lbs of BOD removed.  Carpenter et al.  (7) supplied 5 lbs of  nitrogen and 1.0 l b of phosphorus per 100 lbs of BOD applied i n t h e i r study. Blosser (5), studying de-inking and white water waste, also reported  nitrogen  and phosphorus addition of 5.0 lbs and 1.0 l b per 100 lbs of BOD applied. Amberg (1), reporting on a f u l l - s c a l e m i l l system, found that a B0D:N:P r a t i o of 300:7.5:1 was s u f f i c i e n t to support synthesis.  CHAPTER I I I RESEARCH METHODOLOGY  III.l  RATIONALE The r a t i o n a l e for undertaking  t h i s study  and therefore the basis  of the objectives, stems more from a lack of c l a r i f i c a t i o n as to what people have done i n the past, rather than a need for i n v e s t i g a t i o n of a new system under new conditions. ASBs operating at cold temperatures, and the e f f e c t of temperature changes on ASB operation, have been previously studied under both f i e l d and laboratory conditions (7) (42) (34).  The majority of these  studies have been d e f i c i e n t i n two areas: 1. The operating conditions under which the studies were conducted have not been s p e c i f i e d , i . e . , there i s no i n d i c a t i o n as to whether or not steadystate conditions were achieved. 2. There has been no d e f i n i t i o n of t r e a t ment e f f i c i e n c y ; i . e . , whether treatment e f f i c i e n c y i s a measure of substrate u t i l i z a t i o n or a measure of the decrease i n oxygen demand from the influent to the e f f l u e n t . (The l a t t e r term i s defined i n t h i s paper as system treatment e f f i c i e n c y ) . The d e t a i l i n g of steady-state conditions is necessary because a l l mathematical models used to describe ASB operation are based on the assumption that steady-state conditions e x i s t .  Therefore, any study undertaken to evaluate  these models must be conducted under steady-state conditions. The need for a c l e a r d i f f e r e n t i a t i o n between substrate removal and the decrease i n oxygen demand from the influent to effluent i n ASBs i s perhaps l e s s obvious, but equally important. 14  In treatment systems such as a c t i -  15  vated sludge or t r i c k l i n g f i l t e r s , where there i s a removal of b i o l o g i c a l solids by sedimentation, the difference between per cent substrate removal and the system treatment e f f i c i e n c y may  be s l i g h t .  However, f o r ASBs where  there i s a carry-over of b i o l o g i c a l s o l i d s , the numerical difference i n the e f f i c i e n c y measurement can be s i g n i f i c a n t .  In terms of evaluating design  models and predicting ASB operation, i t becomes necessary to c l e a r l y define what constitutes treatment  efficiency.  The models used to define ASB operation (O'Connor and Eckenfelder's, McKinney's, Chemostat, and f i r s t - o r d e r exponential) are reported to r e l a t e substrate u t i l i z e d or remaining, as a function of a b i o l o g i c a l r e a c t i o n rate constant (K) and treatment time (31)(19(10); yet there has r a r e l y been a clear d i s t i n c t i o n as to j u s t what has been measured i n previous ASB studies. In addition to the lack of c l a r i f i c a t i o n i n previous studies, several of the assumptions behind temperature compensation i n current ASB design pract i c e are questionable.  In order to compensate for an expected decrease i n  treatment e f f i c i e n c y due to decreasing ASB temperatures,  the current practice  has been to increase treatment time by increasing the basin volume.  The  basis of t h i s design practice i s that current design models r e l a t e substrate removal or substrate remaining to treatment time and a reaction rate constant (K).  T h e o r e t i c a l l y , any increase i n substrate remaining due to a decrease i n  the reaction rate constant can be compensated f o r by increasing the time.  treatment  The reaction rate constant at the lower temperature i s simply calculated  using the modified version of the Van't Hoff-Arrhenius equation, presented earlier:  K  T,  =K  T  • 0Tr R T  (10)  16  In current design practice, where temperature compensation for ASBs i s considered, the following assumptions can be  questioned:  1. The design models are applicable over the range of the temperature drop; 2. The b i o l o g i c a l population described by 0 does not change, either i n population size or i n species make-up; and 3. Only the r e s i d u a l substrate portion of the effluent i s a function of temperature, i . e . , the oxygen demand associated with e f f l u e n t s o l i d s i s not considered. In summary, the r a t i o n a l e behind the objectives of this study were: 1. A need to c l e a r l y d e t a i l the operation cond i t i o n s p r i o r to the c o l l e c t i o n of ASB data, i . e . , to establ i s h steady-state operation; 2. A need for a d e f i n i t e d i f f e r e n t i a t i o n between substrate removal and system treatment e f f i c i e n c y i n ASB studies; 3. To question a fundamental assumption of cold temperature operation prediction, i . e . , current design models described the operation of ASBs over a broad temperature range; and 4. To question a further assumption that only the r e s i d u a l substrate portion of ASB effluent changed with temperature. On the basis of t h i s r a t i o n a l e , the study was 1. The laboratory ASB state conditions;  conducted so that  systems could function under steady-  2. A clear d i f f e r e n t i a t i o n between substrate u t i l i z a t i o n and system treatment e f f i c i e n c y existed (this was accomplished by measuring these parameters separately); 3. S u f f i c i e n t data was c o l l e c t e d to evaluate the mathematical models at a cold temperature (3°C); and 4. The proportions of the r e s i d u a l substrate and the b i o l o g i c a l s o l i d s could be determined and compared to similar data c o l l e c t e d i n the 15 - 25°C range.  17  It should be emphasized that t h i s study was not undertaken to formulate a new model to describe ASB operation at cold temperatures, but simply to evaluate the existing models using data c o l l e c t e d at 3°C under controlled steady-state conditions. The nitrogen, oxygen uptake, and s e t t l i n g data were collected and are presented as general information f o r ASB operation at a cold temperature  III.2  (3°C).  GENERAL PROCEDURE In order to develop experimental  temperature, laboratory-scale continuous  data on ASBs operating at a cold  flow ASBs (operating at hydraulic  retention times between one and sixteen days) were maintained temperature of 3°C over a four month period.  at a controlled  The reactor contents were fed  a synthetic waste of powdered skim milk and tap water at two concentration levels:  630 mg/l COD and 1,240 mg/l COD.  (Equivalent to 290 mg/l and 800 mg/l  of BOD^, r e s p e c t i v e l y ) . The reactors were monitored for COD, MLSS and Kjeldahl nitrogen following start-up to determine when steady-state operation was achieved. Considerable e f f o r t was expended on maintaining a constant hydraulic and applied load to the reactors so that i d e a l steady-state conditions were approached. Attainment of steady-state was v e r i f i e d through the measured s t a b i l i z a t i o n of the substrate concentration, effluent q u a l i t y , t o t a l nitrogen concentration of s o l i d s concentration. Once steady-state was attained, a f u l l testing program consisting of COD, B0D,j, Kjeldahl nitrogen, organic nitrogen, ammonia nitrogen, n i t r a t e n i t r o gen, and MLSS analysis was started.  The ASBs were operated at each of the two  18  loadings u n t i l s u f f i c i e n t data on substrate u t i l i z a t i o n , system treatment e f f i c i e n c y , s o l i d s production, nitrogen usage and oxygen uptake were c o l l e c ted.  Batch s e t t l i n g tests were conducted following the completion  continuous  of the  flow studies to evaluate the s e t t l i n g c h a r a c t e r i s t i c s of the  ASB effluent a t 3°C.  III.3  EQUIPMENT A schematic of the laboratory's ASB system i s shown i n Figure 1.  FIGURE  I  SCHEMATIC  OF  MODEL  A S B  19  As shown i n Figure 1, raw milk waste was fed to the ASB reactor by a p r e c i s i o n volume pump which was controlled by a pulse timer.  The reactor  contents were kept completely mixed by an e l e c t r i c mixer and were aerated by diffusers.  The reactors were plexiglass cylinders, capped at one end, and  tapped along the sides so that the effluent would overflow into calibrated containers.  The one-day reactor had a volume of 8.7 l i t e r s ; the other four  were nominally 20 l i t e r s .  The experimental apparatus was contained within a  walk-in temperature room set at 3°C ± 0.5°C. The feed f o r the two, four, eight and sixteen day reactors was pumped from a s i n g l e 20 l i t e r carboy, the contents of which were prepared and changed d a i l y , Monday to Friday. carboy which was r e f i l l e d  The one day reactor was fed from another  every other day.  Feed was maintained over the week-  ends by syphoning from additional carboys. The carboys were stoppered and the a i r vents were plugged with cotton.  Consequently, the build-up of b a c t e r i a l s o l i d s i n the feed bottles  and feed l i n e s was not a problem. In order to achieve steady-state conditions i n the reactors, the hydraulic and applied load to each u n i t had to be maintained at a steady value.  As the concentration of the synthetic waste feed was e a s i l y controlled  i n preparation, both the hydraulic and applied load could be maintained a t a fixed l e v e l by c o n t r o l l i n g the pumping rate. The flow through each reactor was c o l l e c t e d i n calibrated containers and was checked d a i l y . uated cylinder.  The pump flows were checked p e r i o d i c a l l y using a grad-  Evaporation i n the temperature room was found to be n e g l i g i b l e .  Over the period of the study, the flows through the reactors were reasonably constant, as shown i n Table  2.  L i s t e d i n Table  2  are the  20  nominal hydraulic retention times, the mean hydraulic retention times (reactor volume/mean flow) and the standard deviation about the mean hydraulic retention time f o r the f i v e reactors.  TABLE 2 REACTOR HYDRAULIC RETENTION TIME  NOMINAL H.R.T.,DAYS  1 2 4 8 16  MEAN H.R.T.,DAYS  STANDARD DEVIATION . H.R.T.,DAYS  1.0 1.97 3.96 8.6 16.7  ±0.11 ±0.13 ±0.24 ±0.26 ±1.05  The nominal hydraulic retention times are used i n the discussion of reactor performance;  however, the mean hydraulic retention times, as l i s t e d i n  Table 2, were used i n a l l calculations and graphs.  III.4  SUBSTRATE The substrate used i n the experiment was a synthesized mixture of  powdered skim milk and aged tap water.  An analysis of the raw milk waste i s  given i n Table 3. The concentration  of phosphorus and nitrogen i n the milk, i n the  r a t i o of 100:7.5:1 (B0D^:N:P), was more than s u f f i c i e n t to supply any biochemical needs, assuming that both nutrients were i n a r e a d i l y useable form for the organisms.  21  TABLE 3 ANALYSIS OF POWDERED MILK WASTE  1000 mg/l Mixture  ( I n i t i a l Analysis)  Phosphorus 7 mg/l Inorganic carbon 3 mg/l Organic carbon 43.2 mg/l Organic nitrogen 52 mg/l Inorganic nitrogen 0.0 mg/l COD 1048 mg/l BOD o690 mg/l BOD 850 mg/l Suspended solids (Gooch) 0.0 mg/l F i l t r a b l e solids (Whatman #4) 0.0 mg/l F i l t r a b l e solids (Millipore 0.45y) 0.0 mg/l B0D : Nitrogen rPhosphorus 100:7.5:1 5  600 mg/l Mixture  ( F i r s t Loading)  Organic nitrogen Inorganic nitrogen COD BOD,. 1200 mg/l Mixture  30 0.3 630 290  mg/l mg/l mg/l mg/l  65.0 1.0 1240 800  mg/l mg/l mg/l mg/l  (Second Loading)  Organic nitrogen Inorganic nitrogen COD BOD'  Also from Table 3, i t can be seen that the COD/BOD r a t i o i s 1.25, u  which means that 80 per cent of the measured COD i s biodegradable. B0D r a t i o 5  The COD:  (high loading) of 1.53 f a l l s within the reported C0D/B0D range  for actual dairy wastes (38).  5  22  Typical physical and chemical c h a r a c t e r i s t i c s of the Vancouver tap water, as determined by the Greater Vancouver Water D i s t r i c t , are shown i n Table 4 (47). TABLE 4 GREATER VANCOUVER WATER DISTRICT PHYSICAL & CHEMICAL ANALYSIS OF WATER SUPPLIES  CAPILANO INTAKE  Appearance Odour Turbidity pH Total residue Total fixed residue Total v o l a t i l e residue Total a l k a l i n i t y as CaCO, T o t a l hardness as CaCO^ Chloride as C l Sulphate as SO^ Fluoride as F S i l i c a as S102 Ammonia as N N i t r a t e as N N i t r i t e as N Copper as Cu Total Iron as Fe Dissolved Oxygen S p e c i f i c Conductance i n micromhos/cm at 25°C  Clear Nil 0.4 6.4 17.5 ppm 9.6 ppm 7.9 ppm 2.7 ppm 4.6 ppm 0.3 ppm 1.7 ppm Less than 0.05 ppm 3.2 ppm Less than 0.01 ppm Less than 0.1 ppm Less than 0.002 ppm Less than 0.02 ppm O.OS1 ppm ppm 11.7 13.7  Powdered milk was used i n synthesizing the raw waste f o r the following  reasons. 1. The waste would contain only a soluble and c o l l o i d a l portion. 2. The feed mixture would pass through a 0.45 f i l t e r without a loss of c o l l o i d a l s o l i d s , yet any b i o s o l i d s i n the effluent could be removed by this f i l t r a t i o n . The r e s i d u a l substrate  23  concentration could then be determined using normal a n a l y t i c a l techniques f o r COD or BOD^; a simple subtraction from the COD or BOD^ feed concentration would give substrate utilization. 3. The milk s o l i d s would pass through a gooch c r u c i b l e and glass f i l t e r ; therefore the mixed l i q u o r suspended s o l i d s determination would not be affected. 4. The mixture i s representative of an i n d u s t r i a l dairy waste.  III.5  ANALYTICAL PROCEDURES A l l of the a n a l y t i c a l procedures used i n this study, with the excep-  tion of the oxygen uptake rates, were as outlined i n Standard teenth E d i t i o n (40).  Methods  Analyses were made on two types of sample:  effluent and gross e f f l u e n t .  Thir-  filtered  The f i l t e r e d samples were free of b a c t e r i a l  s o l i d s and contained only r e s i d u a l soluble and c o l l o i d a l substrate. samples were prepared  3  These  i n the following manner:  1. An aliquot of the reactor contents was centrifuged for 20 minutes at 2000 rpm to remove coarse s o l i d s . 2. The centrate was f i l t e r e d through a gooch c r u c i b l e and glass f i l t e r , y i e l d i n g a rough f i l t r a t e . 3. The rough f i l t r a t e was passed through a 0.45 m i l l i pore f i l t e r , to remove b a c t e r i a l c e l l s and provide a sample having only substrates. The gross effluent samples were unaltered samples of the reactor contents. The following analyses were carried out on a continuing basis throughout the study. 1.  Chemical Oxygen Demand (COD) on: (a) Feed:  f o r the determination  (b) Reactor contents, gross: efficiency.  of influent oxygen demand.  f o r the determination of system treatment  24  (c) Reactor contents, f i l t e r e d : utilization.  f o r the determination of substrate  (d) Settled e f f l u e n t : f o r the determination of system treatment ciency with post s e t t l i n g . 2. Biochemical Oxygen Demand — (a) Feed:  5 Day (BOD^) on:  f o r the determination of Influent oxygen demand.  (b) Reactor contents, gross: efficiency.  f o r the determination of system treatment  (c) Reactor contents, f i l t e r e d : utilization. 3.  effi-  f o r the determination of substrate  Mixed Liquor Suspended Solids (MLSS) on: (a) Reactor contents, gross: concentration.  f o r the determination of reactor s o l i d s  (b) Settled e f f l u e n t : f o r the determination of suspended s o l i d s l e v e l In the s e t t l e d e f f l u e n t . 4.  Kjeldahl Nitrogen on: (a) Feed: f o r the determination of the t o t a l nitrogen concentration i n the feed. (b) Reactor contents, gross: f o r the determination of the t o t a l nitrogen concentration i n reactors.  5.  Organic and Ammonia Nitrogen on: (a) Feed: f o r the determination of organic and ammonia nitrogen l e v e l i n feed f o r comparison with t o t a l Kjeldahl. (b) Reactor contents, f i l t e r e d ; f o r the determination of organic and ammonia nitrogen l e v e l i n f i l t r a t e , i n order to calculate the n i t r o gen content i n the b i o l o g i c a l s o l i d s .  6.  N i t r a t e Nitrogen on: (a) Feed:  f o r the determination o f the background n i t r a t e l e v e l .  (b) Reactor contents, f i l t e r e d :  f o r the determination of n i t r i f i c a t i o n ,  7. £H: The pH of the reactor contents was determined  periodically.  25  8.  Settling: At the completion of each loading run, batch s e t t l i n g tests were conducted at 3°C using Imhoff cones.  9.  Oxygen Uptake: The oxygen uptake rates were determined using a YSI Model 51 dissolved oxygen probe. The probe was calibrated p e r i o d i c a l l y against a Winkler determination.  CHAPTER IV  RESULTS AND DISCUSSION  IV.1  GENERAL The performance characteristics of the laboratory ASB systems oper-  ating at 3°C are presented and discussed i n this section i n terms of presentday knowledge of ASB operation.  The data points presented are mean values  c o l l e c t e d over the several weeks of steady-state operation. the mean of the suspended solids values are presented The c r i t e r i a used i n determining  due to large f l u c t u a t i o n s .  steady-state operation, and the r e -  s u l t s from the batch s e t t l i n g tests are also presented. data are presented  TV.2  Variations about  The raw steady-state  i n Appendix A.  CRITERIA FOR STEADY-STATE OPERATION Steady-state operation implies that both hydraulic and treatment  e q u i l i b r i a have been reached.  In a completely mixed, flow through system, such  as that used i n t h i s study, one c r i t e r i o n f o r steady-state operation i s that the s o l i d s , l e v e l i n the basin reaches a stable concentration.  At that point, b i o -  l o g i c a l s o l i d s wash-out equals the net s o l i d s production from substrate u t i l i zation.  Steady-state operation can also be documented by the s t a b i l i z a t i o n of  either substrate removal or system treatment e f f i c i e n c y at hydraulic equilibrium. IV.2.1  Low Loading Study Steady-state conditions were achieved at the low loading (BOD^ =  290 mg/l) twenty-four to twenty-seven days a f t e r continuous  26  flow operation was  27  i n i t i a t e d , as shown i n Figure 2 f o r the 16-day reactor.  At this point the  Kjeldahl nitrogen concentration i n the reactor had reached the feed l e v e l , s i g n i f y i n g hydraulic equilibrium, and system treatment e f f i c i e n c y had reached a constant l e v e l .  Similar data f o r the other reactors i s presented i n Appen-  dix B. IV.2.2  High Loading Study Steady-state conditions were achieved i n the high loading run  (BOD^ = 800 mg/l) twenty-five to twenty-nine days a f t e r start-up.  Two to  three weeks a f t e r this run was started, an unusual but i n t e r e s t i n g phenomenon was noted i n the reactors.  The MLSS and f i l t e r e d COD levels started to f l u c -  tuate i n a c y c l i c manner, while the f i l t e r e d BOD^ and gross BOD^ and COD l e v e l s were unaffected.  This c y c l i c phenomenon i s shown i n Figure 3 f o r the two and  sixteen-day reactors.  Cycling i n a b a c t e r i a l system has been described by  Gaudy, et al. (15) i n t h e i r study of t o t a l oxidation of activated sludge and by Thirmurthi (41) studying photosynthetic ponds, who found wide and unexplained v a r i a t i o n s i n f i l t e r e d COD, but not BOD, values. The f l u c t u a t i o n s i n the MLSS and f i l t e r e d COD concentrations r a i s e the question of non steady-state operation.  However, an examination  of Figures  4 and 5 shows that steady-state conditions were reached i n a l l reactors a f t e r twenty-nine days.  As can be seen from Figure 4, hydraulic equilibrium was  achieved i n a l l the reactors by twenty-nine days. in Figure 5, system treatment  By the same time, as shown  e f f i c i e n c y had s t a b i l i z e d .  SYSTEM TREATMENT o  ro O C  Ui  m ro  v.  EFFICIENCY,  P0  o  %(COD)  OJ  o  o  _4_  o  _1_  ro  co H  m > o -<  ro-  CO H > H  m CD  o > -< 3J m > o  TJ  m 3  o o  H O 3J  f  1  CO H  m > o -<  10  O  > < m  r o > g  o r~ o -n m x rn o o o z o o  OV  z  CO  -<  CO H  m 3J  m >  a  m z  9 z  m  OJ m OJ  3 «3 ro cr>GO  o m z o -<  \  ro  83  -ro KJELDAHL  T  r-o o NITROGEN  I  UJ  o C O N C E N T R A T I O N , rng  /-6  CO H > H  rn  FIGURE  3.  CYCLIC  FLUCTUATIONS  OF  FILTERED  COD  CONCENTRATIONS  -E z UJ CD  70  2 day  O  r  I day  STEADY S T A T E ( h y d r a u l i c equilibrium)  •  e  1  CH  eed concentration 6 6 . 0 m g / l 60 X <  -i  50 ^  a: o  40  6 day  UJ  t-  o  < UJ  tr  3/8/72  3 TEST  FIGURE 4. HYDRAULIC  7  4  14/9/72  PERIOD, Weeks  E Q U I L I B R I U M - HIGH  LOADING  o  +>.  60.  > O  zLL!  STEADY -  STATE  50 •  o  O  40-  A  A  "O  O  <?  O  Ix. U_ UJ  h* Z LU  < til DC  • 30-  4  20A  A  I DAY  .  2 DAY 4 DAY  4  i  10-  CO CO  o  ©  l  — I  >  • A  H  Lti  A  0 •  8 DAY  o  o  +  + 16  DAY "TP  -T~  2 10/8/72 F I G U R E 5,  3  4 TEST  PERIOD,  5  6  WEEKS  STEADY - S T A T E - (SYSTEM COD HIGH L O A D I N G  TREATMENT  7 14/9/72 EFFICIENCY  8  Co  32  IV.3  PER CENT SUBSTRATE REMOVAL AND SYSTEM TREATMENT EFFICIENCY The p r i n c i p l e operating parameter f o r an ASB i s treatment  ciency.  effi-  Presented i n t h i s section are the r e s u l t s f o r two e f f i c i e n c i e s :  cent substrate removal and the system treatment e f f i c i e n c y .  per  Per cent substrate  removal i s the per cent decrease i n the applied substrate and i s equal to 100 per cent minus the per cent of substrate remaining i n the reactor.  System t r e a t -  ment e f f i c i e n c y i s the per cent decrease i n the oxygen demand (BOD^ or COD) measured between the i n f l u e n t and the e f f l u e n t , and as such, takes into consideration the oxygen demand associated with generated . iv.3.1  solids.  Per Cent Substrate Removal (Substrate U t i l i z a t i o n ) .  Per cent substrate removal as a function of mean hydraulic retention time i s plotted i n Figure 6.  Curves A and B r e l a t e per cent substrate removal on a  COD basis f o r the two loadings studied; curves C and D are on a BOD^ b a s i s . As can be seen from Curves C and D i n Figure 6, there i s v i r t u a l l y complete u t i l i z a t i o n (94 - 98 per cent) of the substrate i n two to three days, as measured by BODy  On a COD basis, Curves A and B, substrate removal continues  u n t i l about eight days, a f t e r which per cent removal i s constant at 77 - 80 per cent.  From the milk waste analysis, Table 3, i t can be seen that the B0D /C0D u  r a t i o i s 1:1.25, i . e . , 80 per cent of the influent COD i s biodegradable, i n dicating that for retention times beyond eight days, there i s v i r t u a l l y complete u t i l i z a t i o n of the biodegradable portion of the substrate, measured by either COD or BOD^.  Applying this same reasoning, that i s , only 80 per cent of the  COD i s biodegradable, there i s 75 - 85 per cent u t i l i z a t i o n of the biodegradable substrate i n one to two days. A possible explanation for the difference i n time needed to achieve the same per cent substrate removal when measured on a COD or BODc basis may be  P E R C E N T  S U B T R A T E  4^  Ol  CT>  o  o  o  3 «Q ^  3 «Q >s  3 03 \  o  3 «rt ^  R E M O V A L 00  CD  o  o  O  -o  34  the formation of intermediate compounds i n the reactors.  It can be suggested,  because of the l i m i t a t i o n s of the BOD^ test, that the COD curves are a better representation of the effect of mean hydraulic retention time on substrate r e moval at 3°C. Comparative ASB substrate removal data could not be found i n the literature.  However, Hoover et al. (21) documented very rapid and complete  oxidation of dairy wastes i n batch studies at 30°C.  They found that 500 ppm  of sludge s o l i d s would oxidize 1000 ppm of milk s o l i d s i n six hours.  Comparing  these data with data from this study, i t would appear that milk wastes can be oxidized at least three times as rapidly at 30°C as they can at 3°C. IV.3.2  System Treatment E f f i c i e n c y .  The system treatment e f f i c i e n -  cies measured i n the laboratory ASB systems are plotted i n Figure 7 as a funct i o n of mean hydraulic retention time.  Curves A and B are on a COD basis and  Curves C and D are on a BOD^ basis f o r the two loadings. As shown i n Figure 7, system treatment e f f i c i e n c y continues to increase with mean hydraulic retention time over the range of the study, reaching 80 per cent (BODtj) or 51 per cent (COD) at sixteen days. The system treatment e f f i c i e n c i e s (BOD^) measured i n this study at 3°C are generally equal to, or lower than, reported cold temperature ASB t r e a t ment e f f i c i e n c i e s .  Carpenter et al. (7), treating pulp and paper wastes i n the  laboratory at 2°C, found e f f i c i e n c i e s of 56 per cent to 79 per cent f o r retention times of 2.5 to 10 days.  Esvelt et al. (14), treating f r u i t processing waste, r e -  ported e f f i c i e n c i e s of 85 to 88 per cent f o r retention times of 10.5 - 11.5 days i n the 4° - 7°C range.  Reid (34) and Goodrow (20) report treatment e f f i c i e n c i e s  in excess of 80 per cent f o r domestic sewage treated i n twenty day lagoons at near zero temperatures i n Alaska and at Regina which are comparable to those found i n t h i s study.  35  FIGURE  7  .  SYSTEM OF  MEAN  TREATMENT  EFFICIENCY  AS  HYDRAULIC  RETENTION  TIME  A  FUNCTION AT  3° C .  36  IV.4  EVALUATION OF MATHEMATICAL MODELS USED IN ASB DESIGN IV.4.1  treatment  General.  A fundamental assumption i n p r e d i c t i n g ASB  e f f i c i e n c y at cold temperatures i s that the design model used, given  the r i g h t set of constants, w i l l be applicable at a predicted temperature. Four of the f i v e models presented i n the l i t e r a t u r e review were evaluated as to t h e i r a p p l i c a b i l i t y at 3°C on the basis of the per cent substrate removal and system treatment  e f f i c i e n c y data c o l l e c t e d i n this study.  The  models evaluated were O'Connor and Eckenfelder's, McKinney's, the Chemostat, and the f i r s t - o r d e r exponential.  The f i f t h model, the retardent form of O'Con-  nor and Eckenfelder's equation, was not evaluated as i t s use i s r e s t r i c t e d to the pulp and paper industry. IV.4.2  Evaluation of O'Connor and Eckenfelder's Model.  By far  the most commonly used and frequently reported model i s O'Connor and Eckenfelder given by Equation  1:  =  S o  (1) '  1  1 + Kt  V  To use O'Connor and Eckenfelder's model, the reaction rate constant, K, must be known or calculated. To c a l c u l a t e the constant, Equation (1) i s manipulated i n t the l i n e a r form S /S = Kt+1; o e  S/S (influent substrate concentration/effluent o e  substrate concentration) i s then plotted against t .  The slope of the straight  l i n e drawn through the data points i s then K. Figure 8 i s a plot of S /S o  loadings.  g  against t on a COD basis for the two  As can be seen from t h i s f i g u r e , t h i s relationship of S / S Q  e  to t i s  non-linear and therefore O'Connor and Eckenfelder's model i s not applicable. A s i m i l a r plot of S /S Q  against t on a BOD-  basis would y i e l d a straight l i n e ,  UJ r<  5.0-  cr tco m ID CO  ^  a  UJ  4.0  o  S /S 0  e  )\ K t + I where K is constant  z u j 3.0-  UJ  UJ  < 2  or —  2.0-  h- .  •A  ir> o oo z O co  o  a>  A  o  C O D - 630  mg/-e  COD - 1240 m g / - £  1-0-  o CO  2  "T" 4  6  • T  MEAN HYDRAULIC  FIGURE  8.  EVALUATION S U B S T R A T E  -f— 10 10  12 RETENTION TIME,  ~i—  14a y s d  -T— 16  -I— 18  OF REACTION R A T E C O N S T A N T IK) FOR R E M O V A L ( S e ) (O'CONMER and E C K E N F E L D E R ) .  CO  38  but with a zero slope ( S / S Q  e  i s v i r t u a l l y constant with mean hydraulic reten-  t i o n time a f t e r one day), which i s a non-solution.  Thus, i n terms of describ-  ing per cent substrate removal measured i n the laboratory PSB at 3°C, O'Connor and Eckenfelder's model i s not applicable. Evaluating the same model i n terms of system treatment S /S Q  E  efficiency,  (influent substrate concentration/effluent gross concentration) p l o t s  as a straight l i n e function of the mean hydraulic r e t e n t i o n time for t beyond two days, as shown i n Figure 9.  Reaction rate constants can be calculated  from the study data for retention times beyond two days. these straight l i n e s do not pass through 1.0, BODJJ  data i s f i t t e d using only one  The intercepts of  but vary from 1.3  to 2.1.  The  line.  The measured system treatment  e f f i c i e n c i e s and the system t r e a t -  ment e f f i c i e n c i e s calculated using O'Connor and Eckenfelder's model with the constants calculated from Figure 9, are l i s t e d i n Table 5 f o r comparison. As can be seen from Table 5, O'Connor and Eckenfelder's pseudo f i r s t order model w i l l describe only the system treatment  e f f i c i e n c y measured  i n the laboratory ASBs at 3°C for retention times beyond two days.  S Q / S *  =  O.I50t  +  2.10  3.0-  -  0.030t  +  1.65  = 0.0301  +  1.40  •  BO Dc  =  290  mg/|  o  BOD  =  800  mg/f  2.0•A  o  .4  S /S' 0  e  1.0 -  4 t  FIGURE 9.  6 = M E A N  8  10  H Y D R A U L I C  12  R E T E N T I O N  14 T I M E ,  16  *  COD = 630  mg/l  A  COD = 1240 m g / l  18  Days  E V A L U A T I O N OF R E A C T I O N R A T E C O N S T A N T S K FOR SYSTEM TREATMENT EFFICIENCY AT 3 ° C . ( O ' C O N N E R  AND  E C K E N F E L D E R )  CO VO  TABLE 5 MEASURED AND CALCULATED SYSTEM TREATMENT EFFICIENCIES O'CONNOR AND ECKENFELDER'S MODEL E=  ^  X10  BOD,. EFFLUENT  COD EFFLUENT RETENTION TIME  (Days) 1 2 4 8 16 2 4 8 16  CALCULATED  °%  ABSOLUTE DIFFERENCE  MEASURED  CALCULATED  ABSOLUTE DIFFERENCE  LOADING  MEASURED  •a  23.5% 36.0% 40.4% 46.0% 50.5%  36.0% 36.5% 39.4% 45.3% 53.0%  12.5% 0.5% 1.0% 0.7% 2.5%  35.6% 62.5% 61.0% 73.2% 76.6%  56.7% 59.0% 63.3% 70.3% 77.8%  21. 1% 3.5% 2.3% 2.9% 1.2%  s o  31.2% 36.9% 43.3% 44.9%  31.0% 33.2% 39.0% 45.0%  0.2% 3.7% 4.-3% 0.1%  18.0% 63.2% 66.0% 80.0%  59.0% 63.3% 70.3% 77.8%  41.0% ,1.1% 4.3% 2.2%  i-i w  41  IV.4.3  McKinney s Model. f  McKinney's model, i n very general terms, i s  based on the premise that a l l of the i n f l u e n t substrate i s u t i l i z e d within the f i r s t day and the remainder of the treatment or retention time i s used f o r the oxidation of generated s o l i d s .  Substrate remaining, active s o l i d s production,  and the e f f l u e n t oxygen demand are described by three i n t e r - r e l a t e d equations: F  F  i  kJt+T  =  <> 3  k F M  V  =  a  1/t + k  a  F  e  =  F  +  k  1 0  M  (4) ?  a  <  5)  Equation (3), which describes substrate remaining i n the basin, i s the same form as O'Connor and Eckenfelder's equation, and l i k e their equation, i t does not describe the substrate removal measured i n this study. L i s t e d i n Table 6 are the substrate concentrations measured i n the laboratory ASBs and calculated using McKinney's equation, F = F^/k^t + 1 . s i m i l a r comparison on a COD basis could not be made as COD available.  The constant K^ f o r 3°C  (108 day "*") was  constants are  A not  extrapolated from McKinney's  values f o r 5°C to 20°C presented i n Goodman (19). As can be seen from Table 6, McKinney's model predicts a and complete substrate u t i l i z a t i o n than was measured i n this study.  more rapid This d i f -  ference could suggest that McKinney's model cannot be extrapolated beyond  42  TABLE 6 MEASURED AND CALCULATED BOD SUBSTRATE CONCENTRATION McKINNEY'S MODEL 5  RETENTION TIME 1  LOW LOADING MEASURED CALCULATED —  —  HIGH LOADING MEASURED j CALCULATED 187 mg/l  7.3 mg/l  2  55 mg/l  1.33 mg/l  22 mg/l  4  12 mg/l  0.67 mg/l  23 mg/l  1.85 mg/l  8  17 mg/l  0.33 mg/l  16 mg/l  0.87 mg/l  14 mg/l  0.15 mg/l  17 mg/l  0.43 mg/l  16  3.7 mg/l  Gross effluent concentrations were calculated using McKinney's three equations; I.e., r e l a t i n g Fe, the effluent BOD^, to F i , the raw waste B0D,j.  Presented i n Table 7 are the measured and calculated effluent BOD,..  In these c a l c u l a t i o n s the MLSS l e v e l s were assumed to be equivalent to the active mass when used i n conjunction with an  evaluated k^^ constant.  As can be seen from Table 7, with the exception of the i n i t i a l points i n each loading, there i s l i t t l e difference between the measured and calculated concentrations. The constants used i n evaluating McKinney's model were extrapolated to 3°C from the values tabled i n Goodman's Design Manual (19).  Goodman tables  a range of values f o r k^ from 0.04 days^to 0.16 days ^ for sludge of f i v e to twenty days at 5°C. To f i n d the appropriate value of k^ within McKinney's range tabled i n Goodman (19), the test data was used to calculate an average k and 7  43  values of k-^Q.  The k^ values calculated were 0.086days  and 0.076 days ^ f o r high loading.  f o r low loading  The k^^ values calculated were: 0.79  days ^ for the low loading and 0.70 days ^ for high loading.  D e t a i l s of  the c a l c u l a t i o n s used i n defining constants k^ and k^^ can be found i n Appendix C.  TABLE 7 MEASURED AND CALCULATED GROSS EFFLUENT B0D CONCENTRATIONS McKINNEY'S MODEL 5  290 mg/l B0D RAW WASTE 5  RETENTION TIME  2 4 8 16  CALCULATED B0D  MEASURED B0D  DIFFERENCE  131 114 88 63  238 109 99 59  107 5 11 4  5  days days days days  mg/l mg/l mg/l mg/l  5  mg/l mg/l mg/l mg/l  mg/l mg/l mg/l mg/l  800 mg/l B0D RAW WASTE 5  RETENTION TIME 1 2 4 8 16  day days days days days  CALCULATED BOD^  MEASURED BOD^  DIFFERENCE  344 323 286 224 165  513 300 306 215 177  169 23 20 9 12  mg/l mg/l mg/l mg/l mg/l  mg/l mg/l mg/l mg/l mg/l  mg/l mg/l mg/l mg/l mg/l  44  IV.4.4 steady-state  Chemostat.  The Chemostat model i s described by the following  equation:  S =  =•  (5)  V -D m  As noted i n the l i t e r a t u r e review the Chemostat i s based on the Monod equation and an equation describing ASB hydraulics. As can be seen from Figure 10, a plot of biodegradable  COD substrate  concentration against d i l u t i o n rate, the Chemostat model gives a reasonable estimate of the r e s i d u a l substrate concentration measured i n the laboratory ASBs at a l l hydraulic retention times and at both loadings. model describes a v a i l a b l e or useable substrate remaining  As the Chemostat  i n the reactor, the  non-biodegradable portion of the feed COD was substracted from that  concentra-  t i o n measured i n the reactors before i t was plotted i n Figure 10 (126 mg/l' at the low loading and 250 mg/l  at the high loading).  The Chemostat curve used i n approximating the f i l t e r e d data at 3°C was f i t t e d using the constants Ks = 323 mg/l and u  substrate = 2.2 days  C a l c u l a t i n g , using the Chemostat equation with the above constants, the washout retention times at the two substrate loadings are 14.8 hours and 17.9 hours, respectively, f o r the low and high loadings. l i m i t e d substrate conditions i s 2.2 days \ 10.9  hours.  The maximum growth rate under un-  which implies a generation time of  This generation time i s of the same order as the reported gener-  a t i o n times of a psychrophylic  s t r a i n of Pseudonomonads at low temperatures  (32). The BOD,, substrate concentration measured i n the reactors d i d not change with mean hydraulic retention time a f t e r one day, and therefore not be described by the Chemostat model.  could  A '  I  0  £  1  1  1  4 6 8 t , MEAN HYDRAULIC  1  •  1  10 |2 14 RETENTION T I M E - D A Y S  1  16  1 18 •I*  1.0  0.25  0.125 D, DILUTION  FIGURE 10. C H E M O S T A T  RATE -  0.0625 l/t,  DAYS"  1  FIT-COD SUBSTRATE  CONCENTRATION  46  IV.4.5  First-Order Exponential.  The f i r s t - o r d e r exponential model i s  described by the following equation:  S /S e  = e-  o  (7)  k t  Like O'Connor and Eckenfelder's model, the f i r s t - o r d e r exponential model can only be used when the reaction rate constant, k, i s known.  The reaction rate  constant, k, can be calculated from a semi-log plot of S /S  against the mean  e  hydraulic retention time, t . As can be seen from Figure 11, semi-log plots of S / S e  (COD  Q  and  BOD,.  for both loadings) against t, the f i r s t - o r d e r exponential equation does not describe the substrate removal measured i n the laboratory ASBs at 3°C.  On a  BOD^  COD  b a s i s , the reaction rate constant i s 0.0 or a non-solution.  On a  basis, the points cannot be approximated by a straight l i n e . The f i r s t - o r d e r exponential model can, however, be used to describe the gross effluent concentration (or on a per cent basis, system e f f i c i e n c y ) i n the laboratory study. and BOD^  treatment  The reaction rate constants, on a  COD  basis for the two loadings, are calculated from the semi-log p l o t s  shown i n Figure 12.  As can be seen from Figure 12, the gross effluent data  can be approximated only for mean hydraulic retention times beyond two days. The f i r s t - o r d e r exponential equation used i s i n the form of S /S e  where C varies from 0.44  to  Q  = C  £  0.70.  L i s t e d i n Table 8 are the system treatment  e f f i c i e n c i e s measured i n  the laboratory and those calculated using the f i r s t - o r d e r exponential equation. It can be seen that the absolute per cent difference between measured and culated system treatment  cal-  e f f i c i e n c y i s less than four per cent for mean hydraulic  retention times greater than two days.  0f40 47  0.20 , © B0D  5  = 290 m g / l  O  o o  0.10  Ul  0.08  o  o  B0D = 8 0 0 m g / l 5  r-  a:  0.06  •{  to EQ 3CO  Q  IU  0.0 4  K = 0.0  0.0 3  o  UJ  a z o o  N  'x  0.02 0.015  UJ < a: H CO CD  K * CONSTANT  ----  V  0  T  r  0  4  t - M E A N  HYDRAULIC  T  8  12 RETENTION  16 TIME,  Days  CO h-  z  0.80 •A  UJ  3  0.60  II <u  CO  A COD = 1240 m g / l  4  u. UJ  COD = 6 3 0 m g / l  0.40 0.30 -\  v K  co°  #  CONSTANT ..A  0.20 0.15  -A  0  i 4  t - M E A N  HYDRAULIC  1  i  i  ,i 8  i  i 12  R E T E N T I O N  i TIME,  i 16  »  Days.  FIGURE II. E V A L U A T I O N OF R E A C T I O N R A T E C O N S T A N T K FOR S U B S T R A T E R E M O V A L AT 3 ° C .  0.90 -  48  0.70•  0.50-  BODg  = 290 mg/l  0.40  S'e/S  0 . 3 0 4.  = 0.49e  0  - 0.046t  0.20 0.15  i 4  i  -r 8  —n-  I F t,  1  16  n  20  doys  0.900,70 o B0D  0.50-  = 800 mg/l  5  - 0 . 0 4 5 t  0.40  s /s e  =0.44e  0  0.30 0.200.15  -I  1  4  1  8  r—  1  t,  days  l  i  l  t  16  12  20  0.900.70-  s;/s  *.  o  s  0  .7oe-°-  0  ,  5  t  0.500.40-  COD = 6 3 0 m g / l  4  0.300.20  -i  1  4  1  1  1  8  r-  1  12  — i  20  16  t,days 1.0  i  0.8 0.6 0.5  4  A  C O D = 1240 m g / l  A  J  , S /S e o  0.4  r t  = 0.62 e  i  0.3 4  FIGURE  12.  C O N S T A N T  12  8  t, E V A L U A T I O N K  FOR  i 16  -,O.OI6t i  •  20  days OF  S Y S T E M  R E A C T I O N  R A T E  T R E A T M E N T  EFFICIENCY.  TABLE 8 MEASURED AND CALCULATED SYSTEM TREATMENT EFFICIENCY , FIRST-ORDER EXPONENTIAL • E - (1 - Ce" ) x 100% kt  COD EFFLUENT RETENTION TIME (Days) 1 2 4 8 16 2 4 8 16  LOADING  Xi  60 •H  & o  MEASURED  CALCULATED  BOD EFFLUENT 5  ABSOLUTE DIFFERENCE  MEASURED  CALCULATED  ABSOLUTE DIFFERENCE  23.5% 36.0% 40.4% 48.0% 50.5%  39.0% 40.0% 42.0% 46.0% 51.0%  14.5% 4.0% 1.6% 2.0% 0.5%  35.6% 60.0% 61.0% 73.2% 76.6%  59.0% 60.5% 63.5% 71.0% 78.0%  23.4% 0.5% 2.5% 2.2% 1.4%  31.2% 36.9% 43.3% 44.9%  32.0% 35.0% 41.0% 46.0%  0.8% 1.9% 2.3% 1.1%  18.0% 63.2% 66.0% 80.0%  56.0% 60.0% 68.0% 79.0%  38.0% 3.2% 2.0% 1.0%  50  IV.5  ASB  SOLIDS  IV.5.1  Solids Production Solids production i n ASBs, and the r e s u l t i n g c h a r a c t e r i s t i c s and  concentration of these s o l i d s i n the effluent stream, are a major factor i n the effectiveness of the ASB i n producing high quality e f f l u e n t s .  The  carry-over  of s o l i d s produced i n the basin can s i g n i f i c a n t l y deteriorate the q u a l i t y of the e f f l u e n t . COD  or BOD^  In t h i s study, there was an increase of as much as 300  mg/l  when the s o l i d s were included i n the effluent measurements. Shown i n Figure 13 are the average mixed l i q u o r suspended s o l i d s  concentrations measured i n the model reactors at the two loadings.  The ranges  of measured concentrations are also shown, as there was considerable variance due to the cycling previously discussed.  The s i m i l a r i t y between the curves i n  Figure 13 for hydraulic r e t e n t i o n times of two to sixteen days, would suggest that the average values are representative.  The trend i n the s o l i d s  concentra-  t i o n with hydraulic retention time i s one of a s l i g h t l y increasing concentrat i o n from two to eight days, followed by a s l i g h t decrease to sixteen days.  This  trend goes against the usual decrease i n s o l i d s concentration expected with i n creasing hydraulic retention time (10). Solids production i n a closed b i o l o g i c a l treatment system i s generally expressed by the equation: Y = aS  r  - bMLSS  where Y = y i e l d or net s o l i d s production i n lbs/day; a = y i e l d f a c t o r , lbs s o l i d s / l b s substrate removed; S  r  = substrate removed, lbs/day;  b = endogenous c o e f f i c i e n t i n %/day; MLSS = mixed liquor suspended s o l i d s , l b s .  (16)  51  ©  HIGH L 0 A D I N G - I 2 4 0 mg/i  COD  A  LOW L O A D I N G - 6 3 0 m g / - f  COD  T  VARIATION  ABOUT  MEAN  1  r  T  -A-  1  1 6  -I 4 t -MEAN  FIGURE  13.  T  •A  1.  1 8 HYDRAULIC  1 10 RETENTION  " 12 T I M E , Doys  r14  MIXED LIQUOR S U S P E N D E D SOLIDS AS A F U N C T I O N M E A N H Y D R A U L I C R E T E N T I O N TIME A T 3 ° C.  16  OF  52  In a flow-through system without solids recycle, such as the model ASBs used i n the laboratory, the hydraulic washout of s o l i d s under steadystate conditions i s j u s t offset by the b i o l o g i c a l y i e l d or net s o l i d s production from substrate u t i l i z a t i o n .  That i s , net solids production equals the  weight of s o l i d s washed out. Listed below i n Table 9 are the values of net s o l i d s production per pound of substrate removal, calculated for the two loadings on a BOD and COD u  basis.  TABLE 9. NET  SOLIDS PRODUCTION PER POUND SUBSTRATE REMOVED  Low Loading (630 mg/l COD)  0.27  l b s / l b COD  0.25  l b s / l b BOD u  High Loading (1,240 mg/l COD)  0.25  l b s / l b COD  0.24  l b s / l b BOD u  The values tabled are the calculated average of the data collected from the two to sixteen day reactors.  The net solids production per pound of substrate  removed, measured i n the one-day reactor at the high loading, i s 0.48 l b s / l b COD or 0.53 l b s / l b BOD . u Eckenfelder  (10) maintains that ASB s o l i d s production  from a soluble  feed w i l l be about 50 per cent of the Influent feed concentration, lb BOD,..  i . e . , 0.5 l b s /  However, Gellman 0-7), c i t i n g several ASB p i l o t studies, reports net  s o l i d s production of 0.10 to 0.25 l b s / l b BOD removed.  53  The s o l i d s production measured In the laboratory ASBs i s the same f o r both the high and low loadings and i s i n l i n e with the values reported by Gellman.  The reason for the difference i n the net s o l i d s pro-  duction measured i n the one-day reactor, and that measured i n the other reactors, i s not r e a d i l y apparent.  four  I t may possibly be due to a physical  agglomeration of the milk s o l i d s i n the bacteria i n the one-day reactor, a l though there i s no evidence to support t h i s .  Another p o s s i b i l i t y may be the  difference i n growth conditions i n the reactors.  The food to micro-organism  r a t i o i n the one-day reactor i s considerably higher than i n the other four. Busch (6) maintains that the y i e l d c o e f f i c i e n t , as well as the reaction rate of b a c t e r i a , i s dependent on the substrate concentration, and, therefore, at a higher food to micro—organism r a t i o , the y i e l d or net s o l i d s production would be higher. IV.5. 2  COD - BOD„ of ASB'Solids5 The carry-over of s o l i d s i n an ASB effluent can contribute s i g n i f i -  cantly to the COD or BOD^ of the e f f l u e n t . study.  This was p a r t i c u l a r l y true f o r this  A comparison of the respective curves i n Figures 6 and 7 shows a marked  difference between the per cent substrate removal and system treatment e f f i c i e n cy, the l a t t e r taking into consideration the BOD,, or COD of the e f f l u e n t s o l i d s . The difference between the respective COD or BOD,, curves i s a measure of the COD or BOD,, t i e d up w i t h the b i o l o g i c a l s o l i d s .  The respective differences between  the measured substrate remaining and the gross effluent concentration,  the reactor  MLSS,.the calculated COD or BOD per unit of MLSS, and the percentage of the e f f l u 5  ent COD or BOD,, contributed by the residual substrate and by the s o l i d s , are summarized i n Table 10.  TABLE 10 EFFLUENT CHARACTERISTICS OF ASBs AT 3°C  1i NOMINAL " RETENTION TIME LOADING (Days) 2 4 8 16  1 2 4 8 16  o •J  X  60  •H  W  EFFL. COD -EFFL. SUBSTRATE COD  MLSS  COD/ MLSS  EFFLUENT SUBSTRATE^ '•EFFLUENT COD %  EFFL. SOLIDS/ EFFL. COD %  EFFL. BOD -EFFL. SUBSTRATE BOD 5  5  MLSS  BOD,./ MLSS  EFFLUENT EFFL. SUBSTRATE/ SOLIDS/ EFFLUENT EFFL. BOD BOD,. : % % 5  201 mg/l 194 mg/l 230 mg/l 235 mg/l  104 mg/l 108 mg/l 116 mg/l 112 mg/l  1.93 1.80 1.97 2.10  54% 52% 37% 35%  46% 48% 63% 65%  160 mg/l 118 mg/l 95 mg/l 60 mg/l  104 108 116 112  mg/l mg/l mg/l mg/l  1.54 1.07 0.82 0.54  32% 11% 13% 19%  68% 89% 87% 81%  522 mg/l 459 mg/l 435 mg/l '368 mg/l 320 mg/l  385 mg/l 226 mg/l 232 mg/l 244 mg/l 224 mg/l  1.35 2.03 1.88 1.51 1.43  45% 42% 41% 43% 47%  55% 58% 59% 57% 53%  300 mg/l 300 mg/l 270 mg/l 195 mg/l 140 mg/l  385 226 232 244 224  mg/l mg/l mg/l mg/l mg/l  0.78 1.33 1.16 0.80 0.65  40% 6% 7% 9% 11%  60% 94% 93% 91% 89%  Ul  55  The data i n Table 10 shows that the major portion of the effluent BOD^  i s due to b i o l o g i c a l s o l i d s concentrations.  Both Eckenfelder (11) and  Goodman (19) show that the major portion of the effluent BOD,, w i l l be contributed by the s o l i d s i n the effluent. of a number  On the other hand, a study  (28)  of ASBs treating pulp and paper wastes at various retention  times found that only  30 per cent of the effluent BOD^  was contributed  by suspended s o l i d s . The B0D per unit of MLSS (0.54 - 1,54 5  lbs B0D /lb MLSS) l i s t e d 5  i n Table 10 are considerably higher than expected. shows a range of values from 0.75 ages of 0 to seven days. factor as low as 0.25 value of 0.60 ages. of 0.10  Eckenfelder  (10)  to 0.30 l b s BOD^/lb MLSS f o r sludge  However, i n h i s design models he has used a  l b s B0D /lb MLSS (11). 5  Goodman (19) uses a  l b s BOD^/lb active s o l i d s for a l l temperatures and sludge  Gellman (17) quotes a number of investigators who - 0.26  found r a t i o s  l b s B0D /lb s o l i d s for wastes treated at 20° to 35°C, as  compared to 0.54  5  - 1.54  l b s B0D /lb MLSS found i n this study at 3°C. 5  A d i r e c t comparison of values may,  however, be misleading, as i t i s  possible that influent s o l i d s are incorporated i n the values reported by Gellman.  With the exception of the data for the one day reactor (high  loading), the BOD^ time.  per u n i t of MLSS decreases with an increasing retention  This would be expected i f endogenous oxidation was occurring.  A similar trend exists on a COD basis at the high loading, whereas at the low loading the r a t i o i s nearly constant. It would appear that the pounds BOD^  per pound MLSS r a t i o s  measured i n t h i s study at 3°C are s i g n i f i c a n t l y higher at higher temperatures.  than r a t i o s measured  It i s also evident from the data presented i n Table 10  56  that the major portion of the effluent BOD^-COD i s due to the presence of biological solids.  Therefore, i t could be argued that the decrease i n t r e a t -  ment e f f i c i e n c y with decreasing temperature,  as reported i n other studies, i s  due l a r g e l y to an increase i n the COD or BOD,, of the b i o l o g i c a l s o l i d s , possibl y through a decrease i n the endogenous oxidation rate.  IV.5.3  S e t t l i n g at 3°C .  In order to reduce the s o l i d s concentration i n  ASB e f f l u e n t s , a common p r a c t i c e has been to follow an ASB with a s e t t l i n g basin.  In conjunction with the s e t t l i n g of s o l i d s , system treatment  effici-  encies have been reported to increase by two to 10 per cent (7) (37) (46). The results of the batch s e t t l i n g tests conducted  i n this study  would seem to be somewhat unusual, i n that the improvement i n system treatment e f f i c i e n c y with s e t t l i n g (COD basis) was much greater than i n d i cated by the l i t e r a t u r e .  System treatment e f f i c i e n c y improved by as much as  62 per cent (from 23 per cent to 85 per cent) i n the one-day ASB to a low of 14 per cent (from 51 per cent to 65 per cent) i n the sixteen day reactor with f i v e days' s e t t l i n g time.  This can be seen by comparing the gross  COD  i n the supernatant, as system treatment e f f i c i e n c y plotted against s e t t l i n g time, with the superimposed curve of COD removal with aeration time (Figures 14 and 15 respectively) f o r the low and high loading.  FIGURE  14.  PERCENT  COD  REMOVAL  WITH  SETTLING  TIME  -  3 ° C - L O W  LOADING  90i  co  20  J  1  i  1 —  2  1  1  1  3  4  5  :  1  1  r-  6  7  8  r-^V  —i  9  10  i  —  16  t - MEAN HYDRAULIC RETENTION OR SETTLING TIME, DAYS FIGURE 15. PERCENT COD REMOVAL WITH SETTLING TIME - HIGH LOADING"  59  The e f f e c t of aeration time on the s e t t l i n g rate does not follow any trend.  However, the effluent from the reactors with the  highest applied load for the two loadings responded most r a p i d l y , and had the greatest o v e r a l l improvement i n system treatment e f f i c i e n c y (62 per cent for the one-day reactor at high loading and 47 per cent for the two-day reactor at low loading) a f t e r f i v e days s e t t l i n g . A comparison of Figure 15 with Figure 16, which i s a plot of supernatant MLSS against s e t t l i n g time a t the high loading, shows a general trend of decreasing COD with decreasing suspended s o l i d s .  A  numerical evaluation of COD removal i n terms of MLSS s e t t l e d , was not performed, as the MLSS numbers must be considered suspect.  The very low  MLSS l e v e l s , and the necessity of taking small samples (40 mis) so as not to unduly a f f e c t the s e t t l i n g test, resulted i n very small weighing d i f ferences after one day (0.0 to 1.3 mg). The substantial increase i n system treatment e f f i c i e n c y with s e t t l i n g , r e l a t i v e to the two to 15 per cent reported  (7) (35)(46), can be  explained i n part by the higher COD or BOD,, per u n i t of MLSS found i n this study.  The increase may also be due i n part to a possible change i n the  s e t t l i n g c h a r a c t e r i s t i c s of ASB b i o l o g i c a l s o l i d s at low temperature. however, would have to be substantiated by future studies. Referring to Figures 15 and 16, and considering both MLSS and gross substrate removal, i t can be seen that a number of combinations are a v a i l a b l e to give a desired removal e f f i c i e n c y and suspended s o l i d s l e v e l .  For example, an effluent q u a l i t y for 1200  This,  60  400 •  300-  ,A  I DAY  •  2 DAY  4 DAY  - A  CO CO  o 200+  8 DAY 16 DAY  < < z  or UJ  a. 3  / CO  100-  I  2 SETTLING  FIGURE  16.  SUPERNATANT  TIME , MLSS  3 ° C - HIGH  DAYS VS S E T T L I N G  LOADING  TIME  61  mg/l  feed, of 60 mg/l mixed l i q u o r suspended s o l i d s and a system treatment  e f f i c i e n c y of 70 per cent can be achieved  by: (a) four days'aeration  with  one-half days' s e t t l i n g ; (b) one day's aeration with 2% days' s e t t l i n g ; eight days' aeration with 2% days' s e t t l i n g . quality could not be achieved day aerations.  Therefore,  (c)  In contrast, the desired effluent  by using any combinations of the two and  i n terms of both percentage removal and  sixteen  suspended  s o l i d s l e v e l , the e f f l u e n t q u a l i t y does not necessarily r e f l e c t the length of retention t i m e — aeration or s e t t l i n g , but i s a function of both. It i s not the intent of t h i s discussion to suggest that the same r e s u l t s would be found for other wastes, or even for t h i s waste, at a temperature other than 3°C.  Rather, i t i s suggested that when there are effluent  suspended s o l i d s r e s t r i c t i o n s and s e t t l i n g f a c i l i t i e s are required, the  design  of the system should take into consideration the r e l a t i o n s h i p between s e t t l i n g and gross substrate removal and,  IV.6  In turn, s e t t l i n g time with aeration time.  NITROGEN STUDIES IV.6.1  General.  Analysis for the various nitrogen compounds was  taken to f i n d : (a) i f n i t r i f i c a t i o n was nitrogen i n the solids; and  occurring at 3°C;  S u f f i c i e n t nitrogen was a v a i l a b l e i n the feed  to ensure that i t would not be growth l i m i t i n g . i n the reactors substantiates  reactors varied from 0.2 mg/l  The presence of NH^  nitrogen  this.  Nitrate Nitrogen.  f a l l i n g between 0.3 mg/l  (b) the amount of  (c) i f the retention time had any e f f e c t on the  balance of nitrogen compounds.  IV.6.2  under-  The concentration of n i t r a t e nitrogen i n the  to 0.6 mg/l,  and 0.5 mg/l.  with the majority of the samples  No apparent r e l a t i o n e x i s t s between  62  the n i t r a t e concentration and retention time, loading, or test duration.  The  feed water contained about 0.4 mg/l n i t r a t e nitrogen and i t i s l i k e l y that t h i s i s the major source of n i t r a t e nitrogen i n the reactors. ground l e v e l i t was taking place.  Due to the high back-  impossible to determine whether or not n i t r i f i c a t i o n  Wild et al.  was  (44), studying n i t r i f i c a t i o n k i n e t i c s , documented o  very reduced n i t r i f i c a t i o n at 5 C with a decrease i n a c t i v i t y with decreasing temperature. IV.6.3  Nitrogen Balance.  The gross k j e l d a h l nitrogen or t o t a l  nitrogen  i n the system, ignoring the n i t r a t e concentration, averaged 29.6 mg/l low loading and 66.4 mg/l  at the  at the high loading and i n each case was within ex-  perimental l i m i t s of the feed.  Gross nitrogen concentrations measured i n the  reactors at the two loadings are l i s t e d i n Table  11.  Plotted i n Figure 17 against retention time are the concentrations of the f i l t e r e d organic and NH^  nitrogen, and the concentrations of the n i t r o -  gen t i e d up with the s o l i d s for the high loading.  As can be seen from Figure  17, the concentration of nitrogen i n the solids decreases with retention time and i s r e f l e c t e d by an increase i n the f i l t e r e d NH^  concentration.  The  organic  nitrogen concentration remains constant with retention time, which suggests that bacteria capable of converting organic nitrogen to NH^ i n each reactor.  A rigorous explanation as to why  are well established  the proportion of nitrogen  t i e d up with the s o l i d s decreases with retention time i s not a v a i l a b l e .  How-  ever, the increase i n NH^ nitrogen concentration i n the reactors, without a change i n the organic nitrogen concentration, would suggest that the decrease i n nitrogen i n the b a c t e r i a l s o l i d s i s due to a release of NH^ ous oxidation of the s o l i d s .  through endogen-  63  TABLE 11 GROSS KJELDAHL NITROGEN CONCENTRATIONS Low Loading - Feed Concentration 30.3 mg/l: RETENTION TIME (Days)  GROSS CONCENTRATION  2 4 8 16  29.4 mg/l 29.2 mg/l 30.4 mg/l 29.4 mg/l  High Loading - Feed Concentration 66.0 mg/l: RETENTION TIME (Days)  GROSS CONCENTRATION /  1 2 4 8 16  66.3 65.5 66.6 67.1 66.6  mg/l mg/l mg/l mg/l mg/l  The nitrogen data f o r the low loading, as can be seen i n Table 12, does not show any r e l a t i o n s h i p to retention time. TABLE 12 AVERAGE NITROGEN CONCENTRATIONS - LOW LOADING RETENTION .TIME. (Days) 2 4 8 16  GROSS KJELDAHL NITROGEN 29.0 mg/l 29.6 mg/l 30.4 mg/l 29.4 mg/l  NH3 NITROGEN 4.1 4.9 3.4 3.3  mg/l mg/l mg/l mg/l  INORGANIC NITROGEN 4.8 mg/l 5.8 mg/l 5.3 mg/l 9.1 mg/l  .TOTAL NITROGEN CONCENTRATION IN SOLIDS  ,NH CONCENTRATION IN F I L T R A T E 3  ORGANIC NITROGEN 'IN F I L T R A T E  FIGURE  1  i  2  4  17  l  i  I  6 8 10 MEAN H Y D R A U L I C R E T E N T I O N  CONCENTRATION SOLIDS  i  AND  RETENTION  OF  NITROGEN  FILTRATE TIME  AS  (HIGH  A  I  1  12 TIME,  14 days  COMPOUNDS  FUNCTION  LOADING).  OF  IN T H E M E A N  i 16  r 18  REACTOR HYDRAULIC  65  The nitrogen used per hundred pounds of BOD^ applied measured i n t h i s study varied from 8.4 to 6.7 pounds at the low loading and 8.0 to 5.4 pounds at the high loading f o r hydraulic retention times of one to sixteen days.  I t should be noted that Ludzack et at.  (25) found 5.6 to eight per  cent nitrogen i n activated sludge v o l a t i l e suspended s o l i d s at 5°C. These values are approximately twice the nitrogen addition per hundred pounds of BOD^ removed reported for ASBs operating a t temperatures of 20°C to 35°C (1).  (13)(7)(5)  This higher nitrogen requirement may be related to the higher COD and BOD  of the b i o l o g i c a l s o l i d s measured i n this study.  However, i t i s quite possibly  just an example of excess nutrient uptake by b a c t e r i a l s o l i d s when there i s a surplus of nutrients.  IV.7  pH The pH of the reactor contents were nearly constant and remained  s l i g h t l y basic at 7.0 to 7.2.  IV.8  OXYGEN UTILIZATION Oxygen uptake rates of 0.5 mg/1 per hour i n the sixteen day reactor  to 5.3 mg/l per hour i n the one day reactor were recorded  at the high loading  (see Figure 18).  Oxygen u t i l i z a t i o n i n b i o l o g i c a l systems i s often expressed  by the following  equation:  0 lbs/day = a'S lbs/day - b'MLSS lbs/day 2  (17)  r  where a' = oxygen u t i l i z a t i o n c o e f f i c i e n t , l b s 0 used/lb substrate removed; S = substrate removed, lbs/day; b^ = endogenous r e s p i r a t i o n c o e f f i c i e n t , %/day; MLSS = mixed l i q u o r suspended s o l i d s , lbs. 2  FIGURE  18.  OXYGEN  UPTAKE  AGAINST  RETENTION  TIME  67  Figure 19, a plot of lbs oxygen used/lb MLSS against l b s substrate used/lb MLSS, y i e l d s a' as the slope and b' as the intercept.  On a BOD,,  basis, a' i s 0.143 l b s 02/lb substrate used i n the two to sixteen day reactors.  On a COD basis a' i s 0.123 lbs 0 / l b substrate used i n the two to 2  sixteen day reactors and 0.156 lbs 02/lb substrate reactor.  used i n the one day  The endogenous r e s p i r a t i o n rate, b', i s 0.18 l b s 02/lb MLSS per  day, or 0.75 mg/hr per gram of MLSS i n both cases —  as would be expected.  The endogenous r e s p i r a t i o n rate of 0.75 mg/hr per gram MLSS, or approximately  0.95 mg/hr per gram VSS (assuming VSS = 0.8 MLSS) i s consider-  ably lower than many reported values.  Symons (10) reported a mean rate of  15 mg/hr per gram VSS f o r mixed sludges at room temperature. reported a rate of 12 mg/hr per gram VSS for dairy wastes.  Porges (10) However, the  rate i s comparable to the 0.80 mg/hr per gram VSS r e s p i r a t i o n rate found by Esvelt et al. (14) for f r u i t processing wastes treated i n an ASB at 6°C. The depressed rate of endogenous r e s p i r a t i o n would indicate that endogenous oxidation i s much slower at 3°C than at higher temperatures. Shown i n Figure 20 i s a l i n e a r r e l a t i o n s h i p between the f i l t e r e d COD concentration remaining  and the oxygen uptake rates.  A comparison of  Figures 19 and 20 would suggest that r e l a t i o n s h i p between the oxygen uptake rate and the substrate remaining  i s l i k e l y better for the short  retention times than the r e l a t i o n s h i p between oxygen consumed and substrate removed.  68  0.36-8 *  A  I day R.T.  0.300  A 2 days RT.  CO  s a =0143 l b . 0 / C 0 D r e m 2  < a  0.20a = 0.123 lb 0 / l b CODrem v  cc  2  UJ CL O Ul 2 3 tO  A 4 days R.T.  z o o z  ui  o >X o  CIO o A 8 days R.T. o  A  O  C0D-I240mg/^  A  B0D -800mg/-E 5  16 doys R.T. b = 0.018 lbs 0 / M L S S - d a y 1  2  0.0  T  1 I r 1.0 2.0 lbs. S U B S T R A T E REMOVED PER DAY / lb. M L S S  FIGURE 19.  "  OXYGEN CONSUMPTION PER DAY AS A FUNCTION OF SUBSTRATE REMOVED PER DAY - HIGH LOADING.  69  6.04  5-0-1  E  •  4,0  LU  < tr < 3.0 o_ z>  z UJ  o  > o 2,0  1.0  i————r 0  100 REACTOR  200  —i  i  300  COD SUBSTRATE  400  i 500  C O N C E N T R A T I O N , mg /  4  FIGURE 20. OXYGEN U P T A K E RATE AS A FUNCTION OF REACTOR S U B S T R A T E CONCENTRATION  CHAPTER V SUMMARY  The primary objectives of t h i s study, the d e t a i l i n g of ASB operation at a cold temperature and the evaluation of that operation i n terms of current ASB models, were f u l f i l l e d .  V.l  Summarized below are the r e s u l t s of the study.  STEADY STATE Steady state conditions were achieved at both loadings twenty-seven  to twenty-nine days a f t e r the runs were i n i t i a t e d . f i l t e r e d COD  C y c l i c fluctuations of the  concentrations and, to a lesser extent, MLSS l e v e l s were noted at  the higher loading.  V.2  PER CENT SUBSTRATE REMOVAL AND  SYSTEM TREATMENT EFFICIENCY  1^ Seventy-five to 85 per cent of the biodegradable portion of the raw milk waste was u t i l i z e d i n the ASBs within one to two days, and there was complete u t i l i z a t i o n of the biodegradable portion of the waste by eight days. The f i l t e r e d COD  data indicated the possible production of intermediate compounds  which were u t i l i z e d by about eight days at both loadings. 2* The system treatment e f f i c i e n c y varied with retention time from 18 per cent at two days to 80 per cent at 16 days on a B0D basis and from 23 per 5  cent at one day to 51 per cent at 16 days on a COD b a s i s . 3c The per cent substrate removal measured was higher than reported treatment e f f i c i e n c i e s and i s l i k e l y a d i f f e r e n t measurement.  70  On the other hand,  71  the measured system treatment e f f i c i e n c i e s were comparable to reported  treat-  ment e f f i c i e n c i e s i n ASBs operating at low temperature.  V.3  MODEL EVALUATION 1.  Only the Chemostat model would describe the substrate removal data  measured i n the laboratory ASBs at 3°C. 2.  O'Connor and Eckenfelder's, McKinney's, and the f i r s t - o r d e r exponen-  t i a l models could not describe the substrate removal measured at 3°C.  This i n -  a b i l i t y to describe the substrate removal at 3°C could conceivably lessen the usefulness of these models. 3.  O'Connor and Eckenfelder's, McKinney's, and the f i r s t - o r d e r exponential  models would describe system treatment e f f i c i e n c y for mean hydraulic retention times greater than two days.  These models appear to be applicable where endo-  genous oxidation i s the main mechanism of BOD,-  or COD  decay, but, on the basis  of t h i s study, are not applicable under growth conditions.  V.4  SOLIDS PRODUCTION 1.  Net s o l i d s production i n the two to sixteen day ASBs was  lbs per pound of COD  or  BOD  y i e l d was higher, at 0.48 mate.  ultimate removed.  l b s per pound COD  0.25  -  0.27  In the one-day reactor, the net  and 0.53  pounds per pound BOD  ulti-  The net s o l i d s production was not s i g n i f i c a n t l y d i f f e r e n t from that r e -  ported i n other ASB 2„  The COD  studies.  and BOD^  of the generated s o l i d s were s i g n i f i c a n t l y higher  than reported values at higher temperatures; 1.35 and 0.54  - 1.54  mg BOD^  per mg MLSS.  - 2.10 mg COD  per mg MLSS  It i s conceivable, although not proven,  that the change i n the c h a r a c t e r i s t i c s of the generated s o l i d s may  account i n  72  part for the change i n treatment e f f i c i e n c y reported with changes in. the temperature of ASBs. 3.  Post s e t t l i n g at 3°C of the ASB e f f l u e n t resulted i n s i g n i -  f i c a n t increases (14% - 62%) i n system treatment e f f i c i e n c y i n addition to the removal of suspended s o l i d s .  These increases i n system treatment e f f i -  ciency may be due to changes i n s e t t l i n g c h a r a c t e r i s t i c s as well as to the higher COD and BOD of the MLSS measured at 3°C. 5  V.5  NITROGEN USAGE 1.  N i t r i f i c a t i o n did not appear to be s i g n i f i c a n t at 3°C.  2.  The concentration of nitrogen compounds i n the reactor s o l i d s  decreased with retention time at the high loading.  This decrease was r e -  f l e c t e d by an increase i n the NH^ nitrogen concentration i n the effluent with increased retention time. constant, suggesting  The organic nitrogen concentration remains  endogenous oxidation as a possible mechanism for the  release of NH^ nitrogen.  V.6  pH The pH i n the reactors was s l i g h t l y basic at 7.0 to 7.2.  V.7  OXYGEN UPTAKE 1.  The oxygen uptake rates at the high loading varied from 5.25 mg/l/hr  to 0.50 mg/l/hr for retention times of one to sixteen days. 2.  The endogenous r e s p i r a t i o n rate was found to be 0.18 mg/l/hr or  0.75 mg/hr/gram MLSS.  73  3.  Oxygen u t i l i z a t i o n was related l i n e a r l y to substrate removed for  retention times of two to sixteen days — 0.143 and 0.123 l b s 0 4.  2  lbs O2 used/lb BOD,, used  used/lb COD used.  The oxygen uptake rate was related l i n e a r l y to the COD  concentration sixteen days.  substrate  remaining i n the reactors for retention times of one to  CHAPTER VI  CONCLUSIONS  1.  At 3°C twenty-seven to twenty-nine days were required at both  loadings to achieve steady-state conditions i n the reactors.  2.  Seventy-five to 85 per cent of the biodegradable  portion of  raw milk was u t i l i z e d within one to two days and there was v i r t u a l l y complete u t i l i z a t i o n within eight days.  3.  System treatment e f f i c i e n c y varied from 18 to 80 per cent on a  BOD,, basis and 23 to 51 per cent on a COD b a s i s .  4.  The per cent substrate removal measured was higher than reported  treatment e f f i c i e n c i e s and i s l i k e l y a d i f f e r e n t measurement.  System t r e a t -  ment e f f i c i e n c y i s comparable to and i s assumed to be the same as reported treatment e f f i c i e n c i e s .  5.  The Chemostat method described the substrate removal data mea-  sured i n the laboratory ASBs at 3°C.  O'Connor and Eckenfelder's, McKinney's  and the f i r s t - o r d e r exponential models could not describe the substrate removal measured  at 3°C.  This i n a b i l i t y to describe the substrate removal could con-  ceivably lessen the usefulness of these models.  74  75  6.  O'Connor and Eckenfelder's, McKinney's and the f i r s t - o r d e r ex-  ponential models would describe system treatment e f f i c i e n c y for mean hydraulic retention times greater than two days.  These models appear to be applicable  where endogenous oxidation i s the main mechanism of BOD^ or COD decay, but on the basis of t h i s study are not applicable under  7.  growth conditions.  Net s o l i d s production for retention times of two days or greater  i s 25 to 27 per cent of the removed COD or BOD . For a retention time of one u day net s o l i d s production i s about 50 per cent of the removed COD or BOD^.  8.  The COD and BOD,, of the ASB s o l i d s were s i g n i f i c a n t l y higher than  reported values at higher temperatures.  I t i s conceivable although not proven,  that the change i n the c h a r a c t e r i s t i c s of the generated solids may account i n part f o r the changes i n treatment e f f i c i e n c y reported with changes i n the temperature of ASBs.  The higher COD and B0D of the solids may be due to a decrease 5  i n the rate of endogenous oxidation.  9.  Post s e t t l i n g of the ASB effluent at 3°C resulted i n s i g n i f i c a n t  increases (14%-62%) i n system treatment e f f i c i e n c i e s .  The most s i g n i f i c a n t i n -  creases occurred at the shortest retention times and would suggest that d o l l a r s spent on increasing aeration time i n response to expected cold temperatures, would be better spent on s e t t l i n g lagoons with a return of the s o l i d s f o r digest i o n during the warmer months.  10.  This point requires further i n v e s t i g a t i o n .  N i t r i f i c a t i o n did not appear to be s i g n i f i c a n t at 3°C. The concen-  t r a t i o n of Kjeldahl nitrogen i n the ASB solids decreased with retention time at  76  the high loading.  This decrease was  r e f l e c t e d by an increase i n the NH^  gen concentration i n the reactor f i l t r a t e . i n the f i l t r a t e remained constant mechanism f o r the release of NH^  11.  suggesting  The organic nitrogen  nitro-  concentration  endogenous oxidation as a possible  nitrogen.  The endogenous r e s p i r a t i o n rate was  found to be 0.75 mg/hr/gram  MLSS which supports the conclusion of the reduced rate of endogenous oxidation of s o l i d s at  12.  3°C.  Oxygen u t i l i z a t i o n was  retention times of two lbs O2 used/lb COD the COD  related l i n e a r l y to substrate removed for  to sixteen days - 0.143  used.  lbs 0 2 / l b BOD,,  The oxygen uptake rate was  removed or  0.123  also r e l a t e d l i n e a r l y to  substrate concentrate remaining i n the reactors for r e t e n t i o n times of  one to sixteen days.  In addition the curve showing oxygen uptake rate as a  function of hydraulic r e t e n t i o n time takes the same form as the Chemostat model.which follows from the r e l a t i o n s h i p to substrate  concentration.  CHAPTER VII RECOMMENDATIONS  1. and  The high l e v e l s of COD and BOD^ per unit of suspended s o l i d s  the low endogenous r e s p i r a t i o n rate found i n t h i s study suggest that the  decrease i n system treatment e f f i c i e n c y at low temperatures may be related i n part to the make-up of the s o l i d s produced and to endogenous oxidation.  To  prove t h i s supposition, a continuation of t h i s study at at least two other temperatures, preferably 8°C and 15°C i s recommended.  In addition, another two  reactors with retention times of % and 3/4 days could be added to v e r i f y the Chemostat model.  P a r t i c u l a r attention should be paid to improving MLSS deter-  mination, possibly using a power f i l t e r .  In addition to the tests conducted i n  t h i s study, long-term oxidation studies are recommended i n order to e s t a b l i s h the temperature e f f e c t on endogenous oxidation.  2.  Due to the i n a b i l i t y of the current ASB models, with the exception  of the Chemostat, to describe the substrate removal measured i n t h i s study, a complete evaluation of these models should be undertaken.  The evaluation  should  take into consideration both substrate removal and system treatment e f f i c i e n c y over a range of temperatures.  3.  In view of the p r a c t i c a l implications of the s e t t l i n g t e s t s , f u r -  ther and more comprehensive studies are recommended.  These studies should i n -  clude s e t t l i n g tests on the effluent from f i e l d i n s t a l l a t i o n s , as well as from laboratory scale basins, over a range of retention times and temperatures.  77  78  4.  A r e p e t i t i o n of the tests using several i n d u s t r i a l wastes i s  also recommended, i n order to reinforce any conclusions drawn from the milk waste study.  B I B L I O G R A P H Y  Amberg, H. R., J . H. Pritchard and D. W. Wise, "Supplementary > Aeration of Oxidation Lagoons With Surface Aerators," TAPPI 47 (10) 27A (1964). 3  Barnhart, E. L. "Treatment of Chemical Wastes i n Aerated Lagoons," Chem. Eng. Prog. Symp. Ser. 64 90 111 (1968). 3  3  Bartsch, E. H., and C. W. Randall. "Aerated Lagoons — A Report on the State of the A r t , " Jour. Water Poll. Control Federation, 43 699 (1971). 3  Besselievre, P. E. The Treatment of I n d u s t r i a l Wastes. York: McGraw-Hill Book Co.,(1969)  New  Blosser, R. 0. "Oxidation Pond Study for Treatment of De-Inking Wastes," Proc. 16th Ind. Waste Conf. Purdue University (1961). 3  Busch, A. W. Aerobic B i o l o g i c a l Treatment of Waste Water. Texas: Oligodynamics Press (1971).  Houston  Carpenter, W. L., James G. Vanuakias and I. Gellman. "Temperature Relationships i n Aerobic Treatment and Disposal of Pulp and Paper Wastes," Jour. Water Poll. Control Federation 40 733 (1968). 3  3  Dawson, R. N., and J. W. Grange. "Proposed Design C r i t e r i a f o r Waste Water Lagoons i n A r c t i c and Sub-Arctic Regions," Jour. Water Poll. Control Federation 41 237 (1969). 3  E c k e n f e l d e r , W.  W.,  3  and A. J . Englande.  "Temperature  Effects  B i o l o g i c a l Waste Treatment P r o c e s s , " Inter. Symp. on Water Control in Cold Climates pp. 180-190 (1971).  on  Poll.  3  Eckenfelder, W. W. Water Quality and Noble Inc. (1970).  Engineering.  New York:  Barnes  Eckenfelder, W. W., and Davis L. Ford. Laboratory and Design Procedures for Waste Water Treatment Process, University of Texas Pres Tech. Report, EHE-10-6802, Austin, Texas (1968).  80  Eckenfelder, W. W. I n d u s t r i a l Water P o l l u t i o n Control. McGraw-Hill Inc. (1966).  New  York:  Eckenfelder, W. W. 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Design dustrial, Commercial. (1971)..  Handbook of Wastewater Systems: Domestic, InWestport, Conn.: Technomic Publishing Co.  Goodrow, W. E. "Regina Aerates i t s Sewage Lagoon," Water and tion Control, 104, 12, 17 (1966).  Pollu-  Hoover, S. R., L. Josewicz and W. Porges. "Biochemical Oxidation of Dairy Wastes," Proc. 9th Ind. Waste Conf., Purdue University (1954).  Lawrence, A. W., and P. L. McCarty. "Unified Basis f o r B i o l o g i c a l Treatment Design and Operation," Jour. Sanitary Engineering Division, ASCE, 96, No. SA3, 757 (1970).  81  Lee, W. C. "Oxidation Ponds and Aerated Lagoons — Aspects," Can. Jour. Pub. Health, 60, 435 (1969).  Some P r a c t i c a l  Ling, J . T., " P i l o t Study of Treating Chemical Wastes With An Aerated Lagoon," Jour. Water Poll, Control Federation, 35, 963 (1963).  Ludzack, F. J . , R. B. Schaffer and M. B. E l l i n g e r . "Temperature and Feed as Variables i n Activated Sludge Performance," Jour. Water Poll. Control Federation, 33, 141 (1961).  Mancini, J . L., and F. L. Barnhart. " I n d u s t r i a l Waste Treatment i n Aerated Lagoons," Advances in Water Quality Improvement, Vol. I, U n i v e r s i t y of Texas Press, Austin, Texas, pp. 313-324 (1968).  McKinney, R. E. Microbiology McGraw-Hill Inc. (1962).  for Sanitary  Engineers.  New York:  NCASI, "A Study of Mixing C h a r a c t e r i s t i c s of Aerated S t a b i l i z a t i o n , " Stream Improvement Technical B u l l e i n §245, NCASI Inc., New York (1971). Nemerow, N. L. Liquid Wastes of Industry: Theories, Practices and Treatment. Reading, Mass.: Addison Wesley Publishing Co. (1971). Novick, A., and L. Sziland. "Experiments with the Chemostat on Spontaneous Mutations of Bacteria," Proc. Nat. Acad. Sci., Wash., 36, 708 (1950). O'Conner, D. J . , and W. W. Eckenfelder, J r . "Treatment of Organic Wastes i n Aerated Lagoons," Jour. Water Poll. Control Federation, 32, 365 (1960). Olsen, R. H., and J . Jezeski. 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"Temperature Oxygen Requirements i n B i o l o g i c a l Oxidation," Jour. trol Federation, 41, R 463 (1969).  Congress,  E f f e c t s on Energy Water Poll. Con-  Standard Methods for the Examination of Water and Wastewater,• 13th Ed. New York: American Public Health Assoc. Inc. (1972).  Thirmurthi, D. "Design P r i n c i p l e s of Waste S t a b i l i z a t i o n Ponds," Jour. Sanitary Engineering Division, ASCE, 95, No. SA2, 311 (1969). Timpany, P. L., L. E. Harris and K. L. Murphy. Cold Weather Operation in Aerated Lagoons Treating Pulp and Paper Wastes, T. W. Beak Consultants L t d . Townshead, A. R., Sahi Unsal, Boris I. Boyko, "Aerated Lagoon Design Methods: An Evaluation Based on Ontario F i e l d Data," Proc. 24th Ind. Waste Conf., Purdue University, 327 (1969). Wildt, H. F., C. N. Sawyer and T. C. McMohen. "Factors A f f e c t i n g N i t r i f i c a t i o n K i n e t i c s , " Jour. Water Poll. Control Federation, 42, 1845 (1971).  Williams, S. W. J r . , and G. A. Hotto, J r . "Treatment of T e x t i l e M i l l Wastes i n Aerated Lagoons," Proc. 16th Ind. Waste Conf., Purdue Univers i t y , 518 (1961).  83  (46)  White, M. T. "Surface Aeration As A Secondary Treatment System," TAPPI, 48, 10 128A (1965).  APPENDIX A  EXPERIMENTAL DATA  85  TABLE A - l  FILTERED COD RESULTS (630 mg/l feed)  2  DATE  4  DAY  % COD mg/l REMOVAL  COD mg/l  8 DAY  DAY %  REMOVAL  16  DAY  COD mg/l  REMOVAL  COD mg/l  REMOVAL  108  . 82.0  97  84.0  %  %  10/7/72  226  62.2  12/7/72  241  60.0  241  60.0  133  80.0  105  82.7  14/7/72  254  59.7  206  67.3  128  79.7  190  70.0  18/7/72  224  65.5  201  69.0  147  77.4  105  83.7  24/7/72*  340  42.0  250  57.5  222  62.2  257  56.5  AVERAGES  236  61.2  216  65.4  129  79.8  125  80.0  * Temperature room f a i l e d .  86  TABLE A-2 GROSS COD RESULTS (630 mg/l feed)  DATE  2 DAY  4 DAY  8 DAY  COD mg/l  REMOVAL  COD mg/l  REMOVAL  COD mg/l  10/7/72  415  43.2  383  39.2  353  12/7/72  440  26.5  381  36.5  14/7/72  428  30.0  393  18/7/72  464  29.0  21/7/72  410  24/7/72  386  AVERAGES  %  %  16 DAY COD mg/l  REMOVAL  44.0  337  47.5  370  40.0  381  36.5  35.. 5  356  45.0  356  45.0  430  34.0  364  44.0  351  46.0  33.0  388  37.0  350  43.0  327  47.0  34.5  355  39.5  333  43.5  310  47.3  31.2  36.9  %  REMOVAL  43.3  %  44.9  87 TABLE  FILTERED  2 DAY BOD mg/I  6/7/82  —  13/7/72*  140 55  21/7/72  4 %  BOD  REMOVAL  mg/l  BOD  8  DAY  %  BOD  REMOVAL  mg/l  5  BOD5 mg/l  % REMOVAL  94.0  12  96.0  52.0  61  79.0  29  90.4  23  92.0  81.0  15  94.8  15  94.8  15  94.8  Considered  94.4  96.0  suspect; not  TABLE GROSS B O D (290  BOD5 mg/l  REMOVAL  18  *  2  %  5  DAY  97.0  81.0  DATE  16  DAY  9  —  AVERAGES  RESULTS  m g / l feed)  (290  DATE  A-3  4  DAY  5  95.4  i n . average  A-4 RESULTS  m g / l feed)  8  DAY  16  DAY  %  BOD5  %  BOD5  %  REMOVAL  mg/l  REMOVAL  mg/l  REMOVAL  BOD5 mg/l  DAY  % REMOVAL  120  58.5  118  59.5  119  59.0  93  68.0  13/7/72  242  16.5  102  65.5  120  58.5  35  88.0  21/7/72  233  19.5  108  62.5  58  80.0  49  83.0  AVERAGES  238  18.0  109  63.2  99  66.0  42  80.0  7/7/72*  2 Day p o i n t q u e s t i o n a b l e  88  TABLE A-5 MLSS DATA mg/l (600 mg/l milk feed)  DATE 3/7/72 10/7/72 17/7/72 21/7/72 24/7/72*  2 DAY  4 DAY  . 8 DAY  16 DAY  104 112 102 111 152  111 140 128 90 137  108 123 127  105 120 122 96 "103  -  101  F a i l u r e of temperature room  TABLE A-6 NITROGEN DATA mg/l (600 mg/l milk feed)  DATE  GROSS KJELDAHL NITROGEN  NH NITROGEN  10/7/72 14/7/72 18/7/72 AVERAGE  10/7/72 14/7/72 18/7/72 AVERAGE  INORGANIC NITROGEN  10/7/72 14/7/72 18/7/72 AVERAGE  2 DAY  4 DAY  8 DAY  29.7 28.3 29.0  30.0 29.7 29.0 29.6  30.8 30.0 30.5 30.4  29.2 30.3 28.6 29.4  1.9 5.9 4.5 4.1  6.2 3.3 3.1 4.9  3.9 3.4 2.8 3.4  2.2 3.1 4.5 3.3  3.4 7.3 3.9 4.8  2.8 5.9 8.6 5.8  5.3  5.6 10.6 11.2 9.1  -  5.3 5.3  16 DAY  89  TABLE A-7  SETTLING DATA (630 mg/l COD feed)  2 DAY EFFLUENT  SETTLING TIME  COD mg/l  % REMOVAL  4 DAY EFFLUENT  %  8 DAY EFFLUENT  COD mg/l  REMOVAL  COD mg/l  % REMOVAL  16 DAY EFFLUENT  %  COD mg/l  REMOVAL  2 DAY  197  68.8  213  66.0  330  47.7  242  61.7  3 DAY  166  73.6  242  61.7  159  75.0  229  63.7  6 DAY  146  77.0  191  70.0  159  75.0  185  70.5  10 DAY  140  78.0  166  73.8  121  80.8  159  75.0  20 DAY  85  86.5  130  79.2  68  89.0  123  80.5  TABLE A-8 FILTERED COD DATA (1240 mg/l COD feed)  DATE  1 DAY  2 DAY  %  4 DAY  8 DAY  COD mg/l  REMOVAL  COD mg/l  REMOVAL  COD mg/l  25/8/72  478  61.7  237  74.3  403  68.2  221  28/8/72  486  61.2  320  68.9  217  82.6  —  30/8/72  474  62.1  388  64.5  306  74.6  1/9/72  457  63.7  442  72.8  466  3/9/72  455  64.0  332  78.7  8/9/72  348  71.2  256  11/9/72  402  68.3  14/9/72  374  AVERAGE  438  %  %  COD mg/l  %  16 DAY  %  COD mg/l  REMOVAL  299  76.6  —  312  75.0  140  88.8  342  72.6  62.5  202  83.8  213  82.7  248  79.6  316  74.0  301  75.2  78.9  248  79.7  310  74.2  233  80.4  258  78.9  205  83.2  455  62.7  311  74.5  69.4  253  79.2  298  " 75.4  351  71.0  298  75.4  65.2  311  74.5  300  75.7  285  76.8  288  76.5  REMOVAL  REMOVAL 82.7  TABLE A-9 GROSS COD DATA (1240 mg/l COD feed);  DATE  2 DAY  1 DAY  COD  %  REMOVAL  mg/l  REMOVAL  mg/l  REMOVAL  mg/l  REMOVAL  25/8/72  990  20.5  764  40.4  695  45.5  602  51.7  595  53.5  28/8/72  1045  16.5  786  37.0  740  40.5  635  49.0  635  49.0  30/8/72  980  21.5  783  37.4  769  38.5  644  48.5  590  52.8  1/9/72  922  26.6  798  35.8  737  40.7  660  46.8  621  50.0  3/9/72  920  27.1  780  35.8  750  38.3  634  47.9  618  49.1  8/9/72  1135  14.0  805  33.5  736  39.0  645  46.5  619  48.6  11/9/72  880  30.6  796  34.8  713  41.7  637  47.8  607  50.2  14/5/72  857  29.2  789  35.0  728  40.0  637  47.5  615  49.4  18/9/72  915  25.5  788  34.7  750  39.6  659  46.0  609  50.0 .  23.5  36.0  %  46.4  %  COD  mg/l  %  COD  16 DAY  % COD mg/l REMOVAL  AVERAGES  COD  8 DAY  4 DAY  48.0  50.0  TABLE A-10 FILTERED BOD DATA 5  (800 mg/l BOD )  DATE  1 DAY  BOD5 mg/l  2 DAY  % REMOVAL  BOD5 mg/l  4 DAY  % REMOVAL  8 DAY  16 DAY  B0D5 mg/l  % REMOVAL  B0D5 mg/l  % REMOVAL  BOD5 mg/l  % REMOVAL  23/8/72  160  80.0  17  97.9  43  94.7  10  98.7  11  98.6  25/8/72  230  71.2  28  96.5  18  97.7  16  98.0  20  97.5  1/9/72  212  73.5  25  96.9  ' 27  96.6  —  8/9/72  140  82.5  19  97.6  14  98.2  20  97.5  13  98.4  20  97.5  16  98.0  17  97.9  23  97.0  22  97.0  23  97.1  16  98.0  17  97.9  —  14/9/72 AVERAGES  187  76.6  —  —  —  TABLE A - l l . GROSS BOD,. DATA (800 mg/l BOD feed)  DATE  1 DAY  2 DAY  BOD5  %  mg/l  REMOVAL  BOD mg/l  16/8/72  510  36.2  303  23/8/72  500  37.5  25/8/72  528  33.0  13/9/72  360  AVERAGES  515  55.0 35.6  5  **  *  Not average  % REMOVAL  BOD5  %  8 DAY BOD5  %  16 DAY BOD5  %  mg/l  REMOVAL  mg/l  REMOVAL  mg/l  62.1  296  63.0  210  73.7  129  84.0  280  65.0  315  60.6  215  73.1  180  77.5  288  64.0  300  61.7  : 200  75.0  178  77.7  325  59.4  315  60.6  233  70.9  220  72.5  300  62.5  306  61.0  215  73.2  177  76.6  Not at steady state  **  4 DAY  *  REMOVAL  TABLE A-12 MLSS DATA (1200 mg/l milk feed)  DATE  1 DAY  2 DAY  4 DAY  8 DAY  16 DAY  25/8/72  360  233  218  263  —  28/8/72  333  225  230  248  —  30/8/72  357  210  253  230  - 290  1/9/72  340  200  233  223  255  5/9/72  280  153  198  242  250  8/9/72  470  210  217  220  185  11/9/72  390  243  235  228  195  13/9/72  435  285  258  273  215  18/9/72  505  258  255  268  173  95  TABLE A-13 NITROGEN DATA mg/l (1200 mg/l milk feed)  DATE  GROSS KJELDAHL NITROGEN  NH NITROGEN  ORGANIC NITROGEN  1 DAY  25/8/72  67.3  1/9/72  65.0  8/9/72  2 DAY.  4 DAY  8 DAY  16 DAY  67.0  66.3  67.2  65.0  66.9  66.1  66.6  66.5  66.5  66.5  67.6  13/9/72  63.0  65.0  66.5  67.5  69.5  28/8/72  18.0  9.8  21.8  24.0  14.6  5/9/72  15.0  10.9  12.9  7.6  19.6  18/9/72  5.6  10.7  ' 14.0  24.2  22.8  25/9/72  3.36  16.2  14.0  12.9  24.2  28/8/72  6.2  5.6  4.5  4.2  4.8  5/9/72  4.2  4.8  2.5  4.9  18/9/72  4.5  5.5  3.4  5.0  4.5  25/9/72  5.6  4.3  5.0  6.2  5.0  TABLE A-14 BATCH SETTLING DATA (1230 mg/l COD feed)  SETTLING TIME (Hours)  .  1 DAY EFFLUENT  COD % MLSS mg/l REMOVAL mg/l  2 DAY EFFLUENT COD % MLSS mg/l REMOVAL mg/l  4 DAY EFFLUENT COD % MLSS mg/l REMOVAL mg/l  8 DAY EFFLUENT COD % MLSS mg/l REMOVAL mg/l  16 DAY EFFLUENT COD MLSS % mg/l REMOVAL mg/l  606  51.1  —  468  62.2  —  521  58.0  —  575  53.5  —  530  57.2  —  413  66.6  —  452  63.6  —  552  58.0  —  150  521  58.0  120  390  68.5  55  413  66.6  205  552  58.0  185  72.3  —  502  59.5  —  399  67.8  —  399  67.8  —  516  58.3  —  343  72.3  115  478  61.4  55  359  71.0  45  351  71.6  210  454  63.4  110  48  276  77.7  65  470  62.1  0  347  72.0  0  213  82.8  30  466  62.4  20  120  171  86.0  40  490  60.4  10  314  74.7  10  250  79.8  40  432  65.2  60  2  475  61.7  4  375  69.7  6 .  375  69.7  8  343  24  —  VO  97  TABLE A-15 NITRATE NITROGEN DATA  LOADING  1 DAY  2 DAY  4 DAY  8 DAY  16 DAY  12/7/72  Low  0.48 mg/l  0.35 mg/l  0.25 mg/l  0.20 mg/l  18/7/72  Low  0.43 mg/l  0.36 mg/l  0.56 mg/l  0.23 mg/l  24/7/72  Low  0.56 mg/l  0.41 mg/l  0.31 mg/l  0.46 mg/l  12/9/72  High  0.46 mg/l  0.36 mg/l  0.41 mg/l  0.34 mg/l  0.44 mg/l  28/9/72  High  0.49 mg/l  0.46 mg/l  0.45 mg/l  - negl ~  0.51 mg/l  APPENDIX B  TEST DATA PERTAINING TO THE DETERMINATION OF STEADY STATE OPERATION LOW LOADING  TABLE B - l SYSTEM TREATMENT EFFICIENCY LOW LOADING —  COD  START UP TO STEADY STATE  DATE  TIME ELAPSED  2 DAYS R.T.  4 DAYS R.T.  8 DAYS R.T.  27/6/72  11 Days  33%  42%  40%  29/6/72  13 Days  45%  68%  47% _  4/7/72  18 Days  39%  40%  41%  21 days  42%  42%  42%  7/7/72  :  —'  :  STEADY STATE  14/7/72  28 days  30%  35%  45%  18/7/72  32 days  29%  34%  44%  21/7/72  35 days  33%  37%  43%  24/7/72  39 days  34%  39%  44%  APPENDIX C  CALCULATIONS OF THE CONSTANTS K7 AND K10 FOR USE IN McKINNEY'S DESIGN EQUATIONS  101  Average values f o r McKinney's constants K^ and K^Q were found by f i t t i n g the test data to a l i n e a r equation incorporating McKinney's three equations.  F =  i K t + 1  (3)  F  5  K F M  F  a - 5 7 F T K :  e -  F  +  <4>  Va  <> 5  where K  5  = 108 d a y  -1  (extrapolated to 3°C)  - 1  (extrapolated to 3°C)  and K, =  72 d a y  Assume f o r purposes of t h i s c a l c u l a t i o n F  e  - K,„M 10 a  since  FL M » 10 a n  F  Substituting Equation (3) into Equation (4) gives K, • F. ^ i (1/t + K ) ( K • t + 1)  M a  y  Substituting f o r M F  = 6  which i s reworked to  5  i n Equation (5) gives  ^0 * 6 ' i (1/t + KyKKgt + 1) K  F  102  in a y = mx + b form where _ ~  y  X  F (K, • t + 1) e J ^ 1 _ F. • K, t  =  F  i'6 K  m =-K  ?  and B  =  K  10  L i s t e d i n Table C - l are the calculated x's and y's f o r the two loadings.  Figure C - l i s the p l o t of x against y f o r the two loadings.  t h i s plot the average  values are  0.086  day * f o r the low loading and  From 0.076  day ^ f o r the high loading. The K^Q values are 0.79 mg/mg for the low loading and 0.70 mg/mg for the high loading.  TABLE C - l  FEED  F  e  • (K t+1) 5  K ( F ) • (K t+1) ?  x  RETENTION TIME  (mg/l)  1  800  515(108-1+1) 800 • 72  2  290  238(108-1.97+1) 290 • 72  2  800  300(108-1.97+1) 800 • 72  4  290  1 100(108-3.96+1) • 3.96 ' 290 • 72  4  800  306(108-3.96+1) 800 • 72  1 3.96  0.57  8  290  99(108-8.6+1) 290 • 72  1 8.6  0.52  8  800  215(108-8.6+1) 800 • 72  1 8.6  0.40  16  290  46(108-16.7+1) 290 • 72  1 16.7  16  800  177(108-16.7+1) 800 • 72  1 16.7  F  i  ' 6 K  y  fc  e  F  5  1  • K  mx 6  0.955  515(108-1+1) " 7 800 • 72  1 1.97  1.22  -v  238(108-1.97+1) 290 • 72  -2.44K  ?  1 1.97  0.57  300(108-1.97+1) " 7 800 • 72  -1.15K  ?  0.57  137(108-3.96+1) "*7 290 • 72  -2.251^  1 1  .  K  K  ~h  99(108r8.6+l) ~ 7 790 • 72 K  0.31 0.35  306(108-3.96+1) 800 • 72  ^7  -0.955K  -2.25K  ?  -4.46K  ?  215(108-8.6+1) 800 • 72  -3.44*^  215(108-16.7+1) 290 • 72  -5.121^  177(108-16.7+1) 800 • 72  -5.8  K  ?  ?  

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