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Effect of dissolved oxygen concentration on the aerobic stabilization of swine waste Husdon, John Thomas Ross 1973

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EFFECT OF DISSOLVED OXYGEN CONCENTRATION ON THE AEROBIC STABILIZATION OF SWINE WASTE BY John Thomas Ross Husdon B.S.A., U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1960 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER .OF,..SCIENCE .•_ i n the Department o f A g r i c u l t u r e . Mechanics We a c c e p t t h i s t h e s i s as c o n f o r m i n g to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA', SEPTEMBER, 1973 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head o f my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood t h a t c o p y i n g or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed w ithout my w r i t t e n p e r m i s s i o n . Department o f A g r i c u l t u r a l E n g i n e e r i n g & A g r i c u l t u r a l M e c h a n i c s The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date O c t o b e r 10, 1973 ABSTRACT A series of batch tests were conducted to evaluate the e f f e c t of dissolved oxygen concentration on the aerobic s t a b i l i z a t i o n of swine waste. The batch tests were conducted over a 14 day period and the e f f e c t of oxygen concentration was measured by changes i n Chemical Oxygen Demand (COD) of the waste. Three, f i v e l i t r e capacity, digesters were used and were held at the following dissolved oxygen concentra-tions; high 0 2 l e v e l (15-20 mg/1), medium 0 2 l e v e l (5-8 mg/1) and low 0 2 l e v e l (.5- 2 mg/1). The reduction i n COD of the waste at the end of one week of oxidation was 48.7% for the high 0 2 l e v e l , 3 5.3% for the medium 0 2 l e v e l and 15.6% for the low 0 2 l e v e l . The reduction i n COD at the end of 14 days of oxidation was 57.8%, 50.7% and 38.9% respectively for the three levels of oxygen. The addition of one l i t r e of aerated swine waste to four l i t r e s of the raw swine waste did not appreciably a l t e r the reduction i n COD noted i n the above tests. The reduction i n COD for t h i s batch test was 60.9 for the high 0 2 l e v e l , 34.6 for the medium 0 2 l e v e l , and 31.1 for the low 0 2 l e v e l . In t h i s test a l l three levels of dissolved oxygen removed approximately the same percentage of f i l t e r e d COD during the f i r s t two days of oxidation. In the high and medium 0 2 l e v e l digesters t h i s was accompanied by a reduction i n t o t a l COD. A s i m i l a r reduction i n t o t a l COD did not occur at the low 0 2 l e v e l . Correlations were made with the COD determination and determinations for Total Organic Ca-rbon. These c o r r e l a tions were very high (regression c o e f f i c i e n t = .93) when th sample was prepared using a mechanized tissue grinder. Grinding the sample resulted i n a higher value for t o t a l organic carbon as well as an increase i n p r e c i s i o n . i v TABLE OF CONTENTS Pagi Abstract i i Table of Contents i v L i s t of Tables v L i s t of Figures v i Acknowledgements 1 Introduction 2 Literature Review 3 Materials and Methods 1. C o l l e c t i o n Wastes 7 2. Aerobic Digesters 7 3. A n a l y t i c a l Methods 9 4. Batch Treatments (a) Batch Test I - Digester Effects 10 (b) Batch Test II - Oxygen Concentration E f f e c t s 12 (c) Batch Test III - Oxygen Concentration E f f e c t s 12 (d) Batch Test IV - E f f e c t of Oxygen Concentra-t i o n on Waste S t a b i l i z a t i o n after Seeding with Aerated Swine Waste 13 5. Continuous Feed Test 16 Results and Discussion Batch Test I 18 Batch Test II 26 Batch Test III 34 Batch Test IV 46 General Discussion 58 Conclusion 66 References 68 App ndix 70LIST OF TABLES Page Table 1 COD Determinations - Batch Test I 18 Table 2 A n a l y t i c a l Data - Batch Test I 23 Table 3 COD Determinations - Batch Test II 27 Table 4 A n a l y t i c a l Data - Batch Test II 32 Table 5 COD Determinations - Batch Test I I I 34 Table 6 Residue Data - Batch Test I I I 35 Table 7 COD/TOC Ratios and Sample P r e p a r a t i o n 43 Table 8 COD/TOC Ratios and Sample P r e p a r a t i o n A n a l y s i s 45, Table 9 COD Determinations - Batch Test IV 47 Table 10 F i l t e r e d COD Determinations - Batch Test IV 49 Table 11 COD A n a l y s i s - Batch Test IV 51 Table 12 Oxygen Uptake Rates and B a c t e r i a Counts 53 Table 13 COD/TOC Ratios and Sample P r e p a r a t i o n 55 Table 14 E f f e c t of Sample P r e p a r a t i o n on T o t a l Carbon Determinations 56 v i LIST OF FIGURES Page Fi g u r e 1 A e r o b i c D i g e s t e r s 8 F i g u r e 2 A e r o b i c D i g e s t e r s 8 F i g u r e 3 Sampling of D i g e s t e r 11... F i g u r e 4 Measuring D i s s o l v e d Oxygen 11 F i g u r e 5 T o t a l Organic Carbon An a l y z e r 15 F i g u r e 6 G r i n d i n g Sample P r i o r to TOC A n a l y s i s 15 F i g u r e 7 Changes i n Chemical Oxygen Demand of Swine Waste f o r Three D i g e s t e r s (Batch Test I) 20 F i g u r e 8 A Least Squares L i n e a r Regression of COD on time f o r a e r o b i c a l l y d i g e s t i n g swine waste (Batch Test I) 21 F i g u r e 9 F i g u r e 10 F i g u r e 11 F i g u r e 12 F i g u r e 13 F i g u r e 14 Removal Rate of COD with Time f o r Three D i g e s t e r s (Batch Test I) 22 Changes i n Chemical Oxygen Demand of Swine Waste as a f f e c t e d by D i s s o l v e d Oxygen C o n c e n t r a t i o n d u r i n g A e r o b i c S t a b i l i z a t i o n (Batch Test II) 28 Removal r a t e s of COD with time as a f f e c t e d by d i s s o l v e d oxygen c o n c e n t r a t i o n d u r i n g a e r o b i c s t a b i l i z a t i o n (Batch Test II) 29 A l e a s t squares l i n e a r r e g r e s s i o n of COD on time f o r a e r o b i c a l l y d i g e s t i n g swine waste (Batch Test II) 33 Changes i n chemical oxygen demand of swine waste as a f f e c t e d by d i s s o l v e d oxygen c o n c e n t r a t i o n d u r i n g a e r o b i c s t a b i l i z a t i o n (Batch Test I I I ) 37 Removal r a t e s of COD w i t h time as a f f e c t e d by d i s s o l v e d oxygen c o n c e n t r a t i o n d u r i n g a e r o b i c s t a b i l i z a t i o n (Batch T e s t I I I ) 38 F i g u r e 15 A l e a s t squares l i n e a r r e g r e s s i o n of COD on time f o r a e r o b i c a l l y d i g e s t i n g swine wastes(Batch Test I I I ) '39 Page v i i F i g u r e 16 Changes i n t o t a l carbon of swine waste as a f f e c t e d by d i s s o l v e d oxygen con-c e n t r a t i o n d u r i n g a e r o b i c s t a b i l i z a t i o n (Batch Test I I I ) 41 Fi g u r e 17 Changes i n i n o r g a n i c carbon of swine waste as a f f e c t e d by d i s s o l v e d oxygen c o n c e n t r a t i o n d u r i n g a e r o b i c s t a b i l i -z a t i o n (Batch Test I I I ) 42 Fi g u r e 18 A l e a s t squares l i n e a r r e g r e s s i o n on COD on time f o r a e r o b i c a l l y d i g e s t i n g swine waste (Batch Test II and I I I ) 59 Figu r e 19 Changes i n chemical oxygen demand and t o t a l o r g a n i c carbon content o f swine waste d u r i n g a e r o b i c s t a b i l i z a t i o n 61 Fi g u r e 20 Least squares simple r e g r e s s i o n of chemical oxygen demand on t o t a l o r g a n i c carbon content o f swine waste 62 Figu r e 21 Least squares simple r e g r e s s i o n of chemical oxygen demand on t o t a l o r g a n i c carbon content of the f i l t e r e d swine waste 65 1 ACKNOWLEDGEMENTS The writer wishes to express his appreciation for assistance in this study by: Dr. N.R. Bulley, who directed this research, provided encouragement and advice. Dr. W.K. Oldham, for counsel and advice in various aspects of this research and for serving on the research committee and reviewing this thesis. Professor L.M. Staley and Professor T.L. Coulthard for serving on the research committee and reviewing this thesis. Dr. M.A. Tung, for assistance and advice i n the s t a t i s t i c a l analysis of this study. Mr. W. Gleave (Deceased), for assistance and advice i n the design and construction of the digesters. Mr. J. Pehlke, for assistance and advice i n the design and construction of the mixing system. 2 INTRODUCTION Intensified livestock production has resulted i n large volumes of animal waste being produced on small land areas. In many cases there i s i n s u f f i c i e n t land available to re-cycle these wastes in a normal crop production program. This has stimulated research to develop treatment systems that w i l l enable producers to use alternative disposal systems. The treatment of animal waste to reduce i t s p o l l u t i o n poten-t i a l poses a number of d i f f i c u l t problems. Much of the work to date i n animal waste treatment has been based on applying p r i n c i p l e s that were developed for the treatment of municipal sewage. Because of the differences i n the c h a r a c t e r i s t i c s of animal wastes and municipal sewage i t i s quite possible that many of these p r i n c i p l e s are not d i r e c t l y applicable. One of the areas where differences could be encountered is i n the concentration of dissolved oxygen required for s a t i s f a c t o r y aerobic oxidation. The greater e f f i c i e n c y of the high oxygen systems (10) demonstrates that dissolved oxygen concentration can have an ef f e c t on treatment system operations. With the high p a r t i c u l a t e content and the high strength c h a r a c t e r i s t i c s , i n terms of BOD, of animal waste, this could be a factor i n treatment processes using aerobic oxidation. This study i s a series of batch tests to determine what ef f e c t various levels of dissolved oxygen have on the rate of oxidation of swine wastes. This study was also used to examine the use of the Total Organic Carbon analyzer i n animal waste treatment studies. 3 LITERATURE REVIEW The aerobic s t a b i l i z a t i o n of wastes and the oxygen require-ments during this oxidation process have been the topic of many research reports. Most of this research has used municipal waste as a substrate or has been conducted on soluble substrates such as glucose using pure strains of bacteria. The early work in this f i e l d was done by microbiologists and the c l a s s i c a l k i n e t i c model was produced by Monod (11) . This model i s based upon two basic postulates: (i) the c e l l y i e l d factor i s con-stant; ( i i ) the s p e c i f i c growth rate for a culture can be defined by a single continuous function. Considerable controversy has been generated by the Monod equation, p a r t i c u l a r l y i n reference to the c e l l y i e l d factor. Many researchers have reported var-iations i n y i e l d factors due to differences i n substrate, organism and detention time. Eckenfelder (1) ci t e s y i e l d - f a c t o r s varying from .3 to .51 depending on the type of substrate. Much of the controversy regarding c e l l y i e l d can be explained when the fact that c e l l synthesis and endogenous c e l l metabolism are occuring at the same time within the system i s considered. The r e l a t i v e rates at which these processes are proceeding w i l l de-termine the ov e r a l l rate. Despite the controversy with regard to the Monod equation, i t remains as the c l a s s i c a l description of continuous culture growth. In aerobic oxidation systems, oxygen is used to supply energy for synthesis and also for endogenous r e s p i r a t i o n . Eckenfelder (1) outlined the following relationship for the 4 oxygen requirement f o r s y n t h e s i s and endogenous metabolism as: a' S r + b'X r ( C e l l u l a r S y nthesis) a' S r + b'X^ (Endogenous R e s p i r a t i o n ) oxygen requirements f o r c e l l growth oxygen requirements f o r endogenous metabolism BOD5 removed mixed l i q u o r suspended s o l i d s biodegradable mixed l i q u o r suspended s o l i d s Thabaraj (9) c i t e d t h at c r i t i c a l d i s s o l v e d oxygen values range from 0 to .7 m i l l i g r a m s per l i t r e (mg/1) and that r e -commended D.O. l e v e l s f o r a c t i v a t e d sludge p l a n t s range from .5 to 2 mg/1. Irgens and Day (5) c a r r i e d out l a b o r a t o r y s t u d i e s on aero-b i c s t a b i l i z a t i o n of swine wastes. In t h e i r s t u d i e s d i s s o l v e d oxygen was maintained at approximately 1 ppm. T h e i r work r e -s u l t e d i n the development o f design c r i t e r i a f o r an o x i d a t i o n d i t c h to t r e a t swine waste with a g e n e r a l l y recommended d i s -s o l v e d oxygen c o n c e n t r a t i o n of .5 to 2.0 ppm. The U.S. Department of the I n t e r i o r (10) re p o r t e d on the use of hig h p u r i t y oxygen a e r a t i o n f o r c o n v e n t i o n a l a c t i v a t e d sludge p r o c e s s e s . The system s t u d i e d used a d i s s o l v e d oxygen c o n c e n t r a t i o n of 8 to 10 ppm and a l o a d i n g of 7.9 l b s . of BOD5 per day per pound of mixed l i q u o r v o l a t i l e suspended s o l i d s (MLVSS). This was i n c o n t r a s t to a co n v e n t i o n a l a c t i v a t e d sludge p l a n t with a d i s s o l v e d oxygen c o n c e n t r a t i o n of .5 to 2 ppm and a l o a d i n g of .2 to .4 l b s . of BOD5 per day per pound of MLVSS. The high oxygen system p r o v i d e d the same BOD removal 0 2 = and O2 = where a' = h' = S = r X = r 5 with a reduction, i n retention time from 4 hours to 1.5 hours. The endogenous metabolic c o e f f i c i e n t for the high oxygen system was .27 day •}:• and .17 days 1 for the conventional system. This resulted i n considerably less sludge production in the high oxygen system. This research indicates that anaerobic conditions may exist inside the clumps of bacteria i n an aerobic oxidation process. Similar increases i n s t a b i l i z a t i o n rates and subsequent reductions i n c a p i t a l costs and time might be achieved i f higher oxygen concentrations were used during aerobic treat-ment of the high strength animal wastes. The use of the t o t a l organic carbon analyzer as a tool for determining the strength of waste water has been i n v e s t i -gated by several researchers (1, 3, 12). This published work has been centered primarily on the determination of Total Organic Carbon (TOC) and i t s relationship to Biochemical Oxygen Demand (BOD) or Chemical Oxygen Demand (COD). Ford (3) reviewed Total Organic Carbon analysis on domestic and i n d u s t r i a l waste and the BOD/TOC and COD/TOC r a t i o s . He con- , eluded that the TOC measurement would not replace BOD or COD but would be a useful addition to these tests. Williams (12) also reported correlations with TOC, BOD and COD. Eckenfelder (1) discussed the importance of being able to correlate BOD and TOC since the long incubation time required for the BOD test makes i t unsuitable for c o n t r o l l i n g treatment plant processes. Hiser (4) proposed the use of the Total Organic 6 Carbon A n a l y z e r f o r d i r e c t p l a n t c o n t r o l and not as an i n d i -c a t o r of BOD or COD. By monitoring the changes i n the l e v e l of orga n i c and i n o r g a n i c carbon i n the three phases of the system s t u d i e d , he developed an o v e r a l l carbon balance. Robbins (6) made t o t a l o r g a n i c carbon measurements on swine e f f l u e n t s and c o r r e l a t e d these with BOD. He concluded t h a t the BOD and TOC parameters were u s e f u l i n c h a r a c t e r i z i n g swine wastes and waste water. The r a t i o s c a l c u l a t e d f o r TOC/BOD5 and TOC/COD were 1.3 and 2.1 r e s p e c t i v e l y . 7 MATERIALS AND METHODS 1. C o l l e c t i o n of Wastes The wastes used throughout the study were co l l e c t e d from an anaerobic holding tank of a commercial farrow to f i n i s h hog operation. Prior to entering the holding tank, the waste had undergone anaerobic decomposition within the barns and then passed through an overflow system to the tank. Samples were coll e c t e d i n fi v e gallon hard p l a s t i c carboys and transported to the laboratory. 2. Aerobic Digesters The wastes were oxidized in the laboratory using three s p e c i a l l y constructed polyethelene digesters (see Figure 1). These digesters were 10" i n height and 6%" inside diameter and the top was f i t t e d with an 0-ring to ensure that they were a i r t i g h t . A i r was supplied to the digesters by either a small a i r pump or by pressurized cylinders of pure oxygen depending on the dissolved oxygen concentration required. The desired flow and mixture of a i r and oxygen was obtained using a Matheson gas flow meter-blender. The contents of each digester was s t i r r e d using an inverted T-bar located close to the bottom of the digester. The s t i r r i n g apparatus was driven by a two speed motor that was controlled by a rheostat. The motors used were modified automobile windshield wiper motors and operated continuously without any d i f f i c u l t y . Figure 2 shows the digester with the s t i r r i n g motor, gas flow blender and motor control unit. 8 FIGURE 1. A e r o b i c D i g e s t e r s FIGURE 2. A e r o b i c D i g e s t e r s A gas f l o w b l e n d e r B s t i r r e r motor C motor c o n t r o l u n i t 9 The oxygen c o n c e n t r a t i o n o f the d i g e s t e r s was monitored u s i n g an oxygen meter and probe (Yellow Spring Instruments, Model 54). The oxygen probe was f i t t e d with a rubber stopper to ensure that the d i g e s t e r was a i r t i g h t when d i s s o l v e d oxygen measurements were made. The oxygen meter was p e r i o d i -c a l l y c a l i b r a t e d by re a d i n g a water sample of known d i s s o l v e d oxygen c o n c e n t r a t i o n as determined by the Azide M o d i f i c a t i o n of the Winkler method as s e t out i n Standard Methods (8). P r i o r to each measurement, the instrument was c a l i b r a t e d u s i n g a s a t u r a t e d water s o l u t i o n . To determine the d i s s o l v e d oxygen c o n c e n t r a t i o n i n the d i g e s t e r s , the probe was suspended i n the l i q u i d and allowed to come to e q u i l i b r i u m before the readin g was taken. A f t e r being removed from the d i g e s t e r the probe was r i n s e d with d i s t i l l e d water and s t o r e d i n a f l a s k of d i s t i l l e d water. The d e s i r e d oxygen c o n c e n t r a t i o n i n each d i g e s t e r was maintained by a d j u s t i n g the needle v a l v e s on the Matheson Flow Meters. 5. A n a l y t i c a l Methods The waste parameters used to monitor the d i g e s t e r s i n t h i s r e s e a r c h i n c l u d e d : chemical oxygen demand (COD), t o t a l r e s i d u e , t o t a l v o l a t i l e r e s i d u e , t o t a l o r g a n i c carbon, t o t a l K j e l d a h l n i t r o g e n , ammonia n i t r o g e n , pH and temperature. The chemical oxygen demand was performed as o u t l i n e d i n Standard Methods (8) f o r the 20 ml. sample s i z e . A 20 ml sample was taken from the d i g e s t e r and a 5:1 d i l u t i o n prepared u s i n g a v o l u m e t r i c f l a s k . For s o l u b l e COD determinations t h i s d i l u t e d sample was f i l t e r e d (using a #1 Whatman f i l t e r paper) 10 and 20 mis of the f i l t r a t e were used i n the a n a l y s i s . For t o t a l COD determinations the 5:1 sample was d i l u t e d to 10:1 and a 20 ml p o r t i o n was used i n the a n a l y s i s . Values f o r t o t a l r e s i d u e and t o t a l v o l a t i l e r e s i d u e s were obtained as o u t l i n e d i n Standard Methods (8) with the f o l l o w -in g m o d i f i c a t i o n . An exact volume of sample was not used. A sample of the d i g e s t e r contents was t r a n s f e r r e d to a graduated c y l i n d e r and the volume recorded. T h i s sample was then t r a n s -f e r r e d to an e v a p o r a t i n g d i s h and the a n a l y s i s done i n the normal manner. This m o d i f i c a t i o n avoided the problems of s e t t l i n g t h a t i s common with high p a r t i c u l a t e wastes when exact volume measures are taken. T o t a l o r g a n i c carbon determinations were made on a Beck-man Model 915 T o t a l Carbon A n a l y z e r . A Hamilton Automatic hypodermic s y r i n g e was used to i n j e c t a 20 m i c r o - l i t r e sample. The T o t a l Organic Carbon Analyzer was operated u s i n g the pro-cedures o u t l i n e d i n Standard Methods (8) . The pH was measured wi t h a Beckman Model H ph Meter. The temperature was measured u s i n g the temperature sensor i n c o r p o r a t e d with the oxygen probe. The methods used to sample the d i g e s t e r s and measure the d i s s o l v e d oxygen are show i n F i g u r e s 3 and 4. 4. Batch Treatments (a) Batch Test I - D i g e s t e r E f f e c t s T h i s t e s t was c a r r i e d out to determine i f the r a t e of s t a b i l i z a t i o n of the waste was the same i n each of the three d i g e s t e r s when they were operated under e s s e n t i a l l y i d e n t i c a l FIGURE 3 Measuring Dissolved Oxygen 12 c o n d i t i o n s . Each d i g e s t e r was f i l l e d w ith 5 l i t r e s of swine waste. The waste was o x i d i z e d over a 15 day p e r i o d and the ra t e of breakdown of the m a t e r i a l was evaluated u s i n g d a i l y COD d e t e r m i n a t i o n s . The t o t a l r e s i d u e , t o t a l v o l a t i l e r e -si d u e , and K j e l d a h l n i t r o g e n were recorded at the s t a r t and at the end of the t e s t . The d i s s o l v e d oxygen, temperature and pH were determined at v a r i o u s times d u r i n g the t e s t . As the oxygen demand changed duri n g the t e s t , the a i r f l o w was a d j u s t e d so t h a t the d i s s o l v e d oxygen c o n c e n t r a t i o n i n the three d i g e s t e r s was maintained at 6-8 mg/1. (b) Batch Test II - Oxygen C o n c e n t r a t i o n E f f e c t s At the s t a r t of the t e s t each d i g e s t e r was f i l l e d w ith 5 l i t r e s of anaerobic swine waste. Throughout the t e s t , D i g e s t e r 1 was maintained at a low d i s s o l v e d oxygen con-c e n t r a t i o n , .5 to 1.5 mg/1; d i g e s t e r 2 was maintained at a hi g h d i s s o l v e d oxygen c o n c e n t r a t i o n , 15 to 20 mg/1 and d i g e s t e r 3 was maintained at a medium d i s s o l v e d oxygen c o n c e n t r a t i o n , 5 to 8 mg/1. Samples were taken d a i l y from the d i g e s t e r s throughout the 15 day experiment and were analyzed f o r COD, t o t a l r e s i d u e and t o t a l v o l a t i l e r e s i d u e . T o t a l K j e l d a h l n i t r o g e n determinations were made on the con-ten t s of the d i g e s t e r s at the begin n i n g and end of the t e s t run. (c) Batch T e s t I I I - Oxygen C o n c e n t r a t i o n E f f e c t s T h i s t e s t was a repeat o f Batch Test II and i n a d d i t i o n to d a i l y COD, t o t a l r e s i d u e and v o l a t i l e r e s i d u e , t o t a l carbon and t o t a l i n o r g a n i c carbon determinations were made on samples 13 from the digesters every second day. The samples for the Total Organic Carbon Analyzer were given the following treatments before the determinations were made: i) the 20 ml sample from the digester was diluted 10:1 i n a volumetric flask using carbon dioxide free dis-t i l l e d water. Portions (20 ul) of the sample were then injected into the analyzer to determine the t o t a l carbon and inorganic carbon contents (Figure 5). i i ) the digester sample, diluted as i n treatment ( i ) , was allowed to s e t t l e for 10 minutes and 20 u l portions of the supernatant were injected into the analyzer. i i i ) the digester sample, diluted as i n treatment ( i ) , was ground by hand for f i v e minutes using a 7727 pyrex tissue grinder. Portions (20 Ul) of the ground sample were then injected into the analyzer. The values for dissolved oxygen, temperature and pH were recorded at various times. (d) Batch Test IV - E f f e c t of Oxygen Concentration on Waste S t a b i l i z a t i o n After Seeding with Aerated Swine Waste This test was carried out to determine i f seeding the digesters with previously aerated swine waste would a l t e r the effe c t that d i f f e r e n t levels of dissolved oxygen had on the rate of s t a b i l i z a t i o n of the waste. Swine waste which was i n i t i a l l y anaerobic was aerated for 3 days to establish a suitable b i o l o g i c a l culture. The three digesters were each 14 f i l l e d w ith 4 l i t r e s of anaerobic swine wastes and aerated f o r 4 hours to remove the d i s s o l v e d gases. One l i t r e of the p r e v i o u s l y aerated waste was added to each of the d i g e s t e r s and they were monitored over a 15 day p e r i o d . D a i l y COD determinations were made on samples from each of the d i g e s t e r s before and a f t e r f i l t e r i n g u s i n g a #1 What-man f i l t e r paper. T o t a l i n o r g a n i c carbon and t o t a l carbon determinations were made on samples from each of the d i g e s t e r s on a d a i l y b a s i s . The samples were given the f o l l o w i n g treatments before c a r r y i n g out the TOC det e r m i n a t i o n s : i ) the 20 ml sample from the d i g e s t e r was d i l u t e d 10:1 i n v o l u m e t r i c f l a s k s u s i n g carbon d i o x i d e f r e e d i s -t i l l e d water and then 20 u l p o r t i o n s were i n j e c t e d i n t o the an a l y z e r . i i ) the sample, d i l u t e d as i n treatment ( i ) was f i l t e r e d u s i n g #1 Whatman f i l t e r paper and 20 u l p o r t i o n s of the f i l t r a t e were i n j e c t e d i n t o the a n a l y z e r . i i i ) the sample, d i l u t e d as i n treatment ( i ) was ground f o r three minutes u s i n g a 7727 pyrex t i s s u e g r i n d e r attached by a p i e c e of f l e x i b l e rubber hose to a l a b o r a t o r y s t i r r i n g motor (Figure 6 ) . P o r t i o n s (20 ul) of t h i s ground sample were then i n j e c t e d i n t o the a n a l y z e r . T h e n d i s s o l v e d oxygen c o n c e n t r a t i o n was monitored f o r each of the three d i g e s t e r s and was adjus t e d u s i n g the Matheson flow meters so that the d i g e s t e r s were h e l d at the f o l l o w i n g d i s s o l v e d oxygen c o n c e n t r a t i o n s : N o . l , 16 to 20 mg/1; Grinding Sample Prior to TOC Analysis 16 No.2, .5 to 1.5 mg/1; and No. 3, 6 to 8 mg/1. Oxygen up-take r a t e s were determined p e r i o d i c a l l y f o r the three d i g e s t e r s . In t h i s d e t e r m i n a t i o n , the oxygen probe was i n s e r t e d i n t o the d i g e s t e r , the r o t o r speed was i n c r e a s e d to pr o v i d e good a g i t a t i o n and the oxygen supply was shut o f f . The l e v e l of d i s s o l v e d oxygen was recorded at v a r i o u s time i n t e r v a l s andcplots were prepared u s i n g t h i s data. The oxygen uptake r a t e s i n mg/min. were determined from these p l o t s . In the d i g e s t e r s where pure oxygen was used the d i g e s t e r contents were purged with a i r so t h a t the three d i g e s t e r s a l l had the same i n i t i a l oxygen c o n c e n t r a t i o n . Oxygen readings were taken at v a r i o u s time i n t e r v a l s and p l o t s were prepared u s i n g t h i s data. The oxygen uptake r a t e s do not re p r e s e n t a true uptake s i n c e there c o u l d be some t r a n s f e r of oxygen from the area above the l i q u i d back i n t o the l i q u i d . However, s i n c e t h i s c o n d i t i o n e x i s t e d i n a l l three d i g e s t e r s , the oxygen uptake r a t e s do give a comparative r e l a t i o n s h i p f o r the three d i g e s t e r s . 5. Continuous Feed Test An attempt was made to determine the e f f e c t o f d i s s o l v e d oxygen c o n c e n t r a t i o n on a c o n t i n u o u s l y f ed system. The three d i g e s t e r s were f i l l e d with f i v e l i t r e s of anaerobic swine waste and o x i d i z e d f o r 5 days at a d i s s o l v e d oxygen concen-t r a t i o n i n the range of 6 mg/1. On the s i x t h day the contents of the d i g e s t e r s were mixed to assure that the d i g e s t e r s con-17 tained a uniform concentration of swine waste and micro-organisms. Anaerobic swine waste that had been f i l t e r e d through a nylon mesh was placed i n one gallon p l a s t i c car-boys above each digester. A p l a s t i c tube led from each of these carboys to solenoid valves and then to the three digesters. The solenoid valves were controlled by a time clock which allowed a given sized aliquot of the swine waste to flow into the digester each hour. The size of the aliquot was controlled by clamps on the p l a s t i c tubing leading from the solenoid valve to the digester. Overflow ports were i n s t a l l e d i n the digesters. The clamps were set so that the flow was 500 ml/day to each of the digesters and the dissolved oxygen concentra-tions for the digesters were maintained at 1 to 5 mg/1, 4 to 6 mg/1, and 16 to 20 mg/1 respectively. D i f f i c u l t y was encountered i n attempting to maintain a uniform flow into each of the digesters and the t r i a l was terminated after four weeks. 18 RESULTS AND DISCUSSION Batch Test 1 In t h i s t e s t the d i g e s t e r s were given e s s e n t i a l l y i d e n t i -c a l treatment to determine i f there was any d i f f e r e n c e i n the waste parameters monitored f o r the three d i g e s t e r s d u r i n g the treatment p e r i o d . T h i s was done to ensure that i n f u t u r e t e s t s the d i f f e r e n c e between d i g e s t e r s c o u l d be a t t r i b u t e d to t r e a t -ment e f f e c t and not d i g e s t e r e f f e c t . The COD determinations are summarized i n Table 1 and the d a i l y COD determinations are shown i n Table I of the Appendix. The value f o r COD i s the mean of two determinations taken from the same sample. To check the accuracy of the sampling method, s i x e x t r a samples were taken from D i g e s t e r II on day 12. The mean value of these s i x samples was 10,898 mg/1. The value recorded f o r the two r e g u l a r samples on day 12 was 10,149 mg/1 and the d e v i a t i o n between t h i s value and the mean of the s i x e x t r a samples was 6.9%. This d e v i a t i o n i s i n l i n e with the values given f o r the accuracy of COD determinations by Standard Methods (8). TABLE 1 COD Determinations (mg/1) - Batch Test 1 I D i g e s t e r II I I I I n i t i a l Value A f t e r 7 Days o x i d a t i o n Percentage Reduction A f t e r 14 days o x i d a t i o n Percentage Reduction 24000 17091 28.8 10657 55.6 23500 17388 26.0 9300 60.4 24900 16894 32.2 9300 62.7 19 The r e d u c t i o n of COD was q u i t e s i m i l a r f o r each of the d i g e s t e r s . Figure 7 shows the decrease i n COD with time, and e s t a b l i s h e s that the same general r e d u c t i o n i n COD oc-c u r r e d i n a l l the d i g e s t e r s . A l e a s t squares l i n e a r r e g r e s s i o n of change i n COD with time was c a l c u l a t e d from data from each d i g e s t e r . A covar-iance a n a l y s i s was made on t h i s COD data and compared f o r d i f f e r e n c e s i n l e v e l s and s l o p e s . There was no d i f f e r e n c e at the \% s i g n i f i c a n c e l e v e l between D i g e s t e r II and I I I . However, d i g e s t e r I had a lower r a t e of COD r e d u c t i o n than d i g e s t e r s II and I I I . An examination of the d a i l y COD analy-s i s showed that there was very l i t t l e change i n the COD f o r d i g e s t e r I on Days 3, 4, and 5. T h i s l a g phase d i d not show up i n d i g e s t e r II and I I I . The records showed t h a t the d i s s o l v e d oxygen l e v e l i n d i g e s t e r I had dropped to l e s s than 0.1 mg/1 some time a f t e r 4:00 pm on day 2 u n t i l 10:00 am on day 3. T h i s low l e v e l of oxygen appears to have caused the l a g i n COD r e d u c t i o n d u r i n g day 3. An a n l y s i s of the data i n d i c a t e d that a 24 hour l a g phase co u l d account f o r the d i f f e r e n c e s i n slope down to the 1% s i g n i f i c a n c e l e v e l bet-ween d i g e s t e r I and the other two d i g e s t e r s . This i n d i c a t e d that the a e r o b i c treatment of wastes i n the d i g e s t e r s would operate i n the same manner under s i m i l a r c o n d i t i o n s . The computer p l o t s of the a d j u s t e d data are shown i n Figure 8. In F i g u r e 9 the COD removal r a t e s are shown. These were c a l c u l a t e d by p l o t t i n g the value f o r the COD removed per day over the average amount of COD present that day a g a i n s t time. To minimize the d a i l y i r r e g u l a r i t i e s , a moving average 20 FIGURE 7. Changes i n chemical oxygen demand of swine waste f o r three d i g e s t e r s (Batch Test 1). 6 8 10 12 14 TIME (days) 21 FIGURE ^ ) A least squares linear regression of COD on time for aerobically digesting swine waste (Batch Test 1) . 5 \ \ 1 * * ) L. 2 4 6 8 10 12 14 TIME(days) TIME (days) 23 f o r three days data was calculated u s i n g the method o u t l i n e d by F a i r e_t a J , (2) . The c a l c u l a t i o n s and values f o r Fig u r e 8 are i n c l u d e d i n Table II i n the Appendix. The determinations f o r t o t a l r e s i d u e , t o t a l v o l a t i l e r e s i d u e , BOD5 and t o t a l K j e l d a h l n i t r o g e n i n c l u d e d i n Table 2, showed s i m i l a r r e -ductions i n each d i g e s t e r . TABLE 2 A n a l y t i c a l Data* fong/l) - Batch Test 1 TOTAL TOTAL TOTAL RESIDUE VOLATILE RESIDUE BOD 5 KJELDAHL N D i g e s t e r I -Day 1 16162 11086 11850 2801 -Day 15 12281 7230 1000 1883 D i g e s t e r II -Day 1 15610 10431 12500 2713 -Day 15 12620 7326 1000 1847 D i g e s t e r I l l - D a y 1 17001 11698 12000 2775 -Day 15 12405 7333 1250 1887 *Mean value of two t e s t s taken from the same sample. The d i s s o l v e d oxygen was maintained i n the 5 to 8 mg/1 range. This was accomplished f a i r l y e a s i l y f o r the f i r s t s i x days. However, on the seventh day the oxygen demand had i n -creased c o n s i d e r a b l y and by the e i g h t h day, i t was not p o s s i b l e to m a i n t a i n t h i s l e v e l of d i s s o l v e d oxygen u s i n g the a i r pump. During t h i s p e r i o d , the oxygen l e v e l f e l l to the 1 to 3 mg/1 range. T h i s h i g h oxygen demand continued through to the tent h day and then subsided through to the end of the t e s t run. T h i s i n c r e a s e i n oxygen demand was probably due to the i n c r e a s e i n the b i o l o g i c a l p o p u l a t i o n w i t h i n the d i g e s t e r s . T h i s theory i s strengthened by an examination of F i g u r e 9 which shows that the COD removal r a t e f o r the d i g e s t e r s 24 i n c r e a s e d markedly a f t e r day 9, i n d i c a t i n g i n c r e a s e d b i o -l o g i c a l a c t i v i t y . The d a i l y d i s s o l v e d oxygen values f o r the three d i g e s t e r s are i n c l u d e d i n Table I I I of the Appendix. The temperature f o r the d i g e s t e r s ranged from 21° to 27°C and was c o n s i s t a n t f o r the three d i g e s t e r s . T h i s range i n temperature r e f l e c t e d the change i n temperature i n the l a b o r a t o r y . The temperature records are a l s o i n c l u d e d i n Table I I I i n the Appendix. The pH i n a l l three d i g e s t e r s rose c o n s i s t e n t l y from approximately 7.5 at the s t a r t of the t e s t to 8.9 at the c o n c l u s i o n . T h i s change i n pH values i s to be expected duri n g b i o l o g i c a l a c t i v i t y due to the decrease i n v o l a t i l e a c i d content and i n c r e a s e i n the carbonate l e v e l . The d a i l y pH values are a l s o i n c l u d e d i n Table I I I of the Appendix. The three d i g e s t e r s a l l e x h i b i t e d heavy foaming during the i n i t i a l stages of o x i d a t i o n . T h i s heavy foaming con-t i n u e d f o r i t h e f i r s t three days of o x i d a t i o n and then r e -duced g r a d u a l l y u n t i l by the e i g h t h day the foaming was q u i t e s l i g h t . T h i s reduced l e v e l of foam ( I V ) continued through to the end of the experiment. The gaseous exhaust from the d i g e s t e r s was extremely malodourous f o r the f i r s t three days and then odours were n e g l i g i b l e w i t h the ex c e p t i o n of the presence of ammonia. The odour of ammonia was d e t e c t a b l e i n the exhaust gas throughout the e n t i r e t e s t run and t h i s l o s s of ammonia appeared to be the p r i n c i p l e reason f o r the decrease of 25 the t o t a l Kjeldahl nitrogen since periodic determinations of the digester contents showed the n i t r a t e concentration to be less than .5 mg/1. 26 RESULTS AND DISCUSSIONS BATCH TEST II An i n i t i a l test was run to determine the e f f e c t of three levels of dissolved oxygen on the b i o l o g i c a l breakdown of swine wastes during aerobic oxidation. This test was discon-tinued because of the d i f f i c u l t i e s encountered i n maintaining the three levels of dissolved oxygen, Appendix Table IV. To overcome this problem oxygen gas and improved a i r flow controls were added to the system. These additions improved the operation of the system and digester 1 was maintained at a low dissolved oxygen concentration, .5 to 1.5 mg/1; digester 2 at a high dissolved oxygen concentration, 15 to 20 mg/1 and digester 3 at. a medium dissolved oxygen concentration 5 to 8 mg/1 for the 15 day oxidation study (Appendix Table VII). Table 3 summarizes the COD determinations, with the de-t a i l e d d a i l y results shown in Table V of the Appendix. During the f i r s t seven days of observation, the digester with the high dissolved oxygen concentration had a much higher COD reduction than either the medium or low dissolved oxygen digesters. One int e r e s t i n g point i s that the high dissolved oxygen digester reduced a greater percentage of COD during the f i r s t seven days of oxidation than the low dissolved oxygen digester did during the entire f i f t e e n days. 27 TABLE 3 COD Determinations (mg/1) - Batch Test II D i g e s t e r I (low 0 2) II (High 0 2) I I I (Med. 0 2) I n i t i a l Value 32180 30900 31776 A f t e r 7 days o x i d a t i o n 28568 15880 21624 Percentage Reduction 11.2 47.8 32.0 A f t e r 14 days o x i d a t i o n 17800 13014 15886 Percentage Reduction 44.7 57.2 50.0 Fi g u r e 10 shows the decrease of COD with time f o r each of the d i g e s t e r s . The removal of the COD i s shown i n F i g u r e 11 which p l o t s d a i l y removal r a t e s a g a i n s t days. The method of c a l c u l a t i n g the r a t e s of COD removal f o r these p l o t s was on the same b a s i s as i n Batch Test I and the values and c a l c u l a -t i o n s are shown i n Table VI i n the Appendix. The removal r a t e s of COD were markedly d i f f e r e n t f o r the three d i g e s t e r s . The medium and low oxygen treatments both e x h i b i t e d a l a g phase which i n the case of the medium d i s s o l v e d oxygen c o n c e n t r a t i o n , l a s t e d f o r three days at which time the r a t e of removal i n c r e a s e d . For the low oxygen c o n c e n t r a t i o n , t h i s l a g e x i s t e d through to the s i x t h day before an i n c r e a s e i n COD removal was shown. The h i g h l e v e l of oxygen d i d not show t h i s l a g and COD r e -moval began immediately with most of the COD being removed dur-in g the f i r s t seven days. The i n c r e a s e i n removal r a t e by the high and medium oxygen c o n c e n t r a t i o n treatments f o l l o w i n g the n i n t h day of o x i d a t i o n might be a t t r i b u t e d to a change i n the type of s u b s t r a t e being removed. In waste mixtures that con-%8 FIGURE 10. Changes i n chemical oxygen demand of swine waste as affected by dissolved oxygen concentration during aerobic s t a b i l i z a t i o n (Batch Test 11). 8 12 16 TIME (days) 29 FIGURE 11. Removal rates of COD with time (jTTffected by dissolved oxygen concentration during aerobic stabilization (Batch Test 11) . .175 TIME (days) 30 t a i n many s u b s t r a t e s , changes i n removal r a t e c o - e f f i c i e n t s have been:reported (1). During the i n i t i a l stages of opera-t i o n , the e a s i l y removed s u b s t r a t e s r e s u l t i n a high removal r a t e c o - e f f i c i e n t . Once these s u b s t r a t e s have been d e p l e t e d , the removal of the other s u b s t r a t e s takes p l a c e at a lower r a t e . The r e d u c t i o n i n s u b s t r a t e c o n c e n t r a t i o n a l s o a f f e c t s the m i c r o b i a l growth r a t e and r e s u l t s i n changes i n the s u b s t r a t e removal r a t e . With a complex high p a r t i c u l a t e waste such as was used i n t h i s t e s t run, the r e l e a s e of s o l u b l e s u b s t r a t e from the p a r t i c u l a t e matter dur i n g oxida-t i o n , c o u l d a l s o a f f e c t the removal r a t e s . I t can be ..seen i n F i g u r e 10 t h a t f o r the high oxygen treatment the COD vs'time r e l a t i o n s h i p c o u l d be approximated by two d i f f e r e n t l i n e a r f u n c t i o n s , one f o r the f i r s t s i x days and one f o r the l a s t e i g h t days. I t was not p o s s i b l e to adequately d e s c r i b e the decay curve by one l i n e a r func-t i o n throughout. Since the main d i f f e r e n c e s between oxygen l e v e l s occurred d u r i n g the f i r s t seven days (see Table 3), the data was ad-j u s t e d to c o n s i d e r t h i s i n the c a l c u l a t i o n s o f the l i n e a r r e g r e s s i o n p l o t s of COD vs time and the c o v a r i a n c e a n a l y s i s . T h i s was accomplished by i n c l u d i n g only COD values over 16,000 mg/1 s i n c e i t was below t h i s l e v e l t h a t the r a t e of COD r e d u c t i o n dropped o f f s h a r p l y f o r the h i g h oxygen t r e a t -ment. With t h i s adjustment, COD values were i n c l u d e d f o r the f i r s t s i x days f o r the h i g h oxygen treatment and f o r the f i r s t twelve days f o r the medium oxygen treatment, and f o r the e n t i r e o x i d a t i o n p e r i o d f o r the low oxygen t r e a t -31 ment. A s t a t i s i t i c a l analysis of this adjusted data showed that the slope of the li n e a r plot of the high oxygen treat-ment was d i f f e r e n t at the 1% l e v e l of significance from the slope of the medium and oxygen treatments. However, there was no s t a t i s t i c a l difference i n the slopes of the low and medium levels of dissolved oxygen. The l i n e a r plots of the three oxygen treatments are shown i n Figure 12. The differences i n oxygen concentrations of the three digesters did not appear to have any af f e c t on the reduction of t o t a l residue or t o t a l v o l a t i l e residue. The values for t o t a l residue and t o t a l v o l a t i l e residue are summarized i n Table 4 and the d a i l y determinations are included i n Table V of the Appendix. The e f f e c t of oxygen concentration on t o t a l Kjeldahl nitrogen (Table 4) was sim i l a r for the three digesters. The reduction i n t o t a l Kjeldahl nitrogen would appear to be the r e s u l t of str i p p i n g the ammonia gas from the digester contents since less than .5 mg/1 of N03-N was found during periodic analysis of the digester contents. The digesters performed well during this test and the dissolved oxygen were maintained within the desired ranges. The d a i l y dissolved oxygen determinations are included i n Table VII. TABLE 4 A n a l y t i c a l Data (mg/1) - Batch Test II D i g e s t e r I Day 1 (Low 0 2) Day 15 Percentage Reduction D i g e s t e r II Day 1 (High 0 2) Day 15 Percentage Reduction D i g e s t e r I I I Day 1 (Medium 0 2) Day 15 Percentage Reduction TOTAL TOTAL KJELDAHL RESIDUE VOLATILE NITROGEN RESIDUE 23160 17308 3049 19996 14516 1895 13.7 16.1 37.8 21992 16080 2912 18156 13016 1850 17.4 19.1 36.5 21428 16128 3004 19780 14216 1840 7.7 11.8 38.7 33 FIGURE 12. A l e a s t squares l i n e a r r e g r e s s i o n of COD on time f o r a e r o b i c a l l y d i g e s t i n g swine waste (Batch Test 11). 30 25 20 low 0 2 high O 2 Medium 0 2 15 10 felME (days) 10 12 14 34 RESULTS AND DISCUSSION BATCH TEST I I I Batch Test I I I was run to co n f i r m the r e s u l t s o f Batch Test II and t e s t the u s e f u l n e s s of the T o t a l Organic Carbon A n a l y z e r i n l i v e s t o c k waste treatment s t u d i e s . In t h i s batch t e s t d i g e s t e r 1 was maintained at a hig h d i s s o l v e d oxygen c o n c e n t r a t i o n , 15 to 20 mg/1; d i g e s t e r 2 at a medium d i s s o l v e d oxygen c o n c e n t r a t i o n , 5 to 8 mg/1 and d i g e s t e r 3 at a low d i s s o l v e d oxygen c o n c e n t r a t i o n , .5 to 1.5 mg/1. The COD a n a l y s e s , f o r the f o u r t e e n day treatment, are summarized i n Table 5 and the d e t a i l e d d a i l y r e s u l t s are i n c l u d e d i n Table V I I I i n the Appendix. TABLE 5 COD Determinations (mg/1) Batch T e s t I I I I n i t i a l Value A f t e r 7 days o x i d a t i o n Percentage r e d u c t i o n A f t e r 14 days o x i d a t i o n Percentage Reduction I (High 0 2) 30313 15256 49.6(47.8)* 12616 58.4(57.2)* Dige s t er II (Med. 0 2) I I I (Low 0 2) 30993 18972 38.8(32.0)* 15061 51.4(50.0)* 30896 24645 20,2(11.'2)* 20730 32.9(44.7)* C o r r e s p o n d i n g values f o r Batch Test II 35 The percentages of the COD reduced by the three digesters approximate the values obtained for Batch Test I I. The removal of t o t a l residue and t o t a l v o l a t i l e residue, as shown in Table 6, did show a difference i n the amount removed at the high oxygen l e v e l compared to the two lower l e v e l s . This was i n contrast to the results of Batch Test I I . This greater reduction i n residue indicates that the waste has undergone a greater degree of s t a b i l i z a t i o n . Since the wastes were colle c t e d at d i f f e r e n t times, this v a r i a t i o n could be attributed to differences i n the c h a r a c t e r i s t i c of the raw waste. The d a i l y determinations for t o t a l residue and t o t a l v o l a t i l e residue are included i n Table VIII of the Appendix. TABLE 6 Residue Data (mg/1) Batch Test III Digester 1 (High 0 2) Day 1 Day 15 Percentage Reduction Digester 2 (Med 0 2) Day 1 Day 15 Percentage Reduction TOTAL RESIDUE 21138 15774 25.4(17.4)* 21804 17595 19.3(7.7)* TOTAL VOLATILE RESIDUE 15692 10572 32.6(19.1)* 16044 12340 23.1(11.8)* Digester 3 ( Low' °z) Day 1 Day 15 Percentage Reduction 22961 18788 18.1(13.7)* 17068 13444 21.1(16.1)* Corresponding values for Batch Test II 36 The reduction of COD with time, shown i n Figure 13, does not provide as marked a contrast between the medium and high levels of dissolved oxygen as was found i n Batch Test II. The lag i n COD reduction for the medium oxygen, was considerably less i n this test. The low oxygen concentration also had less of a lag phase but displayed the lower overa l l removal that was evident i n Batch Test II. This same relationship occurred i n the rate of COD removal as shown i n Figure 14. The calculations used to develop Figure 13 are shown i n Table IX i n the Appendix. The rate of COD removal for the medium and low dissolved oxygen levels had less of a lag phase than Batch Test II. In contrast, the peak removal rate for the low dissolved oxygen digester was lower than i n the previous batch test. A least squares linear regression of change i n COD with time was calculated for each digester. As i n batch test II the analysis of the slopes of the plots was not v a l i d when a l l the data were used. The data were adjusted to include only values over 16,000 mg/1 COD and a v a l i d analysis was completed showing that the slopes of the three plots were d i f f e r e n t at the 1% le v e l of si g n i f i c a n c e . The l i n e a r plots used i n this analysis are shown i n Figure 15. The digesters generally performed i n the same manner as i n Batch Test II. Daily recordings of dissolved oxygen, temperature, and pH are included i n Table X i n the Appendix. The temperature was uniform for a l l digesters and, as i n 5 I FIGURE 13. Changes i n chemical oxygen demand of swine waste as affected by (dissolved oxygen concentration during aerobic s t a b i l i z a t i o n (Batch Test 111) . FIGURE 14. Removal rates of COD with time as affected by dissofjyed oxygen concentration during aerobic s t a b i l i z a t i o n (B^tch Test 111) TIME (days) :4 FIGURE lf^ vL A least squares linear regression of COD on time for aerobically digesting swine waste (Batch Test 111). medium 0 2 high 0 2 6 8 TIME (days) 10 12 14 40 Batch Test I, r e f l e c t e d the change i n the temperature w i t h i n the l a b o r a t o r y . The pH began with a uniform value of 8.1 and the two higher oxygen l e v e l s i n c r e a s e d to a f i n a l value of 8.9 and 9.0. The pH of the d i g e s t e r contents at the low oxygen l e v e l a l s o i n c r e a s e d but i t had only reached a value of 8.7 at the end of the t e s t . The d i g e s t e r s foamed as i n the p r e v i o u s batch runs and foaming was c o n t r o l l e d u s i n g -an -anti-foaming agent. The t o t a l carbon determinations on the contents from the d i g e s t e r s and the supernatent a f t e r a ten minute s e t t l i n g time, a l l showed a c h a r a c t e r i s t i c d e c l i n e , with time, throughout the o x i d a t i o n p e r i o d . T h i s d e c l i n e was g r e a t e r i n the higher oxygen treatments and f o l l o w e d the general p a t t e r n of the COD d e t e r m i n a t i o n s . The i n o r g a n i c carbon determinations a l l i n c r e a s e d i n value throughout the l e n g t h of the t e s t s with the h i g h e r oxygen l e v e l s showing a l a r g e r i n c r e a s e than the lower oxygen l e v e l . The values f o r t o t a l carbon, i n o r g a n i c carbon and o r g a n i c carbon f o r the three d i g e s t e r s and the three sample treatments are i n c l u d e d i n Table XI i n the Appendix. F i g u r e s . 16 and 1 7 show a r e p r e s e n t a t i v e graph of these values and i l l u s t r a t e s the d e c l i n e of t o t a l carbon and the subsequent i n c r e a s e i n organic carbon d u r i n g the o x i d a t i o n p e r i o d . The COD/TOC r a t i o s were c a l c u l a t e d f o r each sample pre-p a r a t i o n throughout the o x i d a t i o n p e r i o d and these are shown i n Table 7. These r a t i o s remained f a i r l y constant through-C u FIGURE 16. Changes i n t o t a l carbon of swine waste as affected by dissolved oxygen concentration during aerobic s t a b i l i z a t i o n Batch Test 111. t • ( ( c i i 2 4 6 8 10 12 14 TIME (days) FIGURE 17. Changes in inorganic carbon of swine waste as affected by dissolved oxygen concentration during aerobic s t a b i l i z a t i o n (Batch Test 111). TABLE 7 COD/TOC Ratios and Sample P r e p a r a t i o n ri0C o f Supernatant from S e t t l e d I High 0, II Med...O 9 T T T I.nw n .DAY COD TOC COD/TOC COD TOC COD/TOC COD TOC L TOC/COD RATIO RATIO RATIO 0 30313 7500 4.04 30993 7500 4.13 30896 7500 4.12 2 28614 7000 4.09 29283 7600 3.85 29911 7800 3.83 4 23469 5500 4.27 26139 6900 3.78 29478 7400 3.98 6 16900 3900 4.33 19300 4200 4.60 26900 5500 4.89 8 13461 3600 3.74 14824 3700 4.01 24963 6800 3.67 10 14014 2200 6.37 15756 2600 6.06 26656 7100 3.75 12 13132 3000 4.37 14896 2600 5.73 23608 - 5800 4.07 14 12616 2700 4.67 15061 2400 6.28 20730 5300 3.91 TOC oi Ground S ample 0 30313 10100 3.00 30993 9400 3.29 30896 9500 3.25 2 28614 8300 3.95 29283 9200 3.18 29911 9100 3.29 4 23464 6800 3.45 ! 26139 8500 3.08 29478 9500 3.10 6 16900 6400 2.64 ! 19300 6500 2.97 26900 8100 3.32 8 13461 5500 2.45 1 14824 5700 2 .60 24963 9100 2.74 102, 14014 3800 3.69 1 15756 4100 3.84 26656 7300 3.65 12 13132 4700 2.79 14896 5600 2.66 23608 7800 3.03 14 12616 4700 2.68 i 15061 4800 3.13 20730 7000 2.96 ; TOC of Undground Sample 0 30313 8500 3.57 i 30993 8700 3.56 30896 8500 3.63 2 28614 8000 3.58 ; 29283 9100 3. 21 29911 9700 3.08 4 23464 7200 3.26 I 26139 7900 3.31 29478 8600 3.43 6 16900 5100 3.31 [ 19300 6300 3.06 26900 8200 3.28 8 13461 3500 3.85 | 14824 3700 4.01 24963 7100 3.52 10 14014 3500 4.01 i 15756 4100 3.84 26656 7100 3.75 12 13132 3700 3.55 14896 3800 3.92 23608 6500 3.63 14 12616 3400 3.71 15061 4100 3.67 20730 6100 3.40 44 out the o x i d a t i o n p e r i o d which i s i n c o n t r a s t to other r e -por t e d work that showed a decrease i n the COD/TOC r a t i o d u r i n g b i o l o g i c a l o x i d a t i o n o f m u n i c i p a l and i n d u s t r i a l waste waters (1). Table 8 shows an a n a l y s i s of the COD/TOC r a t i o s as they were a f f e c t e d by sample p r e p a r a t i o n . The COD/TOC r a t i o o b tained by u s i n g the TOC of the supernatant d i d not pr o v i d e a r e l i a b l e parameter. The range i n values f o r t h i s COD/TOC r a t i o and the high values and v a r i a t i o n f o r the standard d e v i a t i o n of the mean i n d i c a t e that i t would be d i f f i c u l t to use t h i s type of a parameter to c h a r a c t e r i z e the waste. The g r i n d i n g of the sample pro-v i d e d a c o n s i s t e n t l y h i g h e r value f o r the TOC a n a l y s i s throughout the o x i d a t i o n p e r i o d . T h i s i n c r e a s e i n the TOC value i n d i c a t e s that w i t h a high p a r t i c u l a t e waste the micro-l i t r e s y r i n g e i s d i s c r i m i n a t i n g a g a i n s t the l a r g e r p a r t i c l e s and gives r i s e to a value that i s lower than the true v a l u e . The g r i n d i n g o f the sample d i d not a f f e c t the measure of the i n o r g a n i c carbon content which remained c o n s i s t a n t f o r both the supernatant, ground and unground samples. Since the i n o r g a n i c carbon measures mainly s o l u b l e carbonates and b i -carbonates t h i s was to be expected. G r i n d i n g d i d not improve the accuracy of the COD/TOC de t e r m i n a t i o n . The standard d e v i a t i o n of the means f o r the COD/TOC r a t i o u s i n g an unground TOC sample were i n f a c t lower than the TOC/TOC r a t i o s u s i n g a ground TOC sample. This would i n d i c a t e the g r i n d i n g d i d not make the sample homogenous enough to prevent wide v a r i a t i o n s i n the d e t e r m i n a t i o n s . 45 TABLE 8 COD/TOC Ratios and Sample Preparation - Batch Test III COD/TOC Supernatant Digester I (High 0 2) II (Med. 0 2) III (Low 0 2) No. of Determinations ^ 8 8 8 Range (COD/TOC) 3.74-6.37 3.78-6.28 3.83-4.07 Mean (COD/TOC) 4.49 4.81 4.03 Standard Deviation of Mean 0.81 1.05 0.38 COD/TOC Ground No. of Determinations 8 8 8 Range (COD/TOC) 2.45-3.69 2,.'66V3.89 2.74^3765 Mean (COD/TOC) 3.02 3.09 3.17 Standard Deviation of Mean 0.45 0.38 0.21 COD/TOC Unground No. of Determinations 8 8 8 Range (COD/TOC) 3.26-4.01 3.21-4.01 3.08-3.75 Mean (COD/TOC) 3.61 3.57 3.47 Standard Deviation of Mean 0.25 0.35 0.22 46 RESULTS AND DISCUSSION BATCH TEST IV This batch test was run to determine the e f f e c t of oxygen concentration on the rate of b i o l o g i c a l breakdown of swine wastes that had been seeded with aerated swine waste. In the previous batch tests, a lag i n the rate of COD removal was observed at the s t a r t of the test. This lag was probably due to the lack of a suitable b i o l o g i c a l culture and i t was shorter i n the high and medium levels of dissolved oxygen than in the low l e v e l . This would indicate that the higher levels of dissolved oxygen were more favourable for the establishment of a suitable b i o l o g i c a l culture. The addition of a portion of aerated swine waste to each digester at the s t a r t of the batch test was done to eliminate this lag i n the rate of COD removal. Five l i t r e s of swine waste were aerated for three days maintaining a dissolved oxygen le v e l of 5 to 8 mg/1. At the s t a r t of the batch test each digester was f i l l e d with four l i t r e s of swine waste and one l i t r e of previously aerated swine waste. Digester 1 was maintained at a high dissolved oxygen l e v e l , 15 to 20 mg/1; digester 2, at a low dissolved oxygen l e v e l , .5 to 1.5 mg/1; digester 3 at a medium dissolved oxygen l e v e l , 5 to 8 mg/1. The exhaust gas from a l l three digesters was extremely malodourous but this diminished noticeably by the end of the f i r s t hour. This was i n contrast to the other batch tests where the exhaust gases remained malodourous for 3 to 5 days. 47 The COD of the contents of each of the d i g e s t e r s was determined d a i l y . These values are summarized i n Table 9. TABLE 9 COD Determinations (mg/D - Batch Test IV I (High 0 2 ) D i g e s t e r II (Low 0 2) I I I (Med. 0 2 ) I n i t i a l Value 36000 38600 32120 A f t e r 7 days o x i d a t i o n 20140 30800 24000 Percentage Reduction 44.1(48. 7)* 20.2(15.7)* 26.1(35. 4) A f t e r 14 days o x i d a t i o n 14090 26600 20000 Percentage Reduction 60.9(57. 8)* 31.1(38.8)* 34.6(50. 7) *Average of Batch Test II and I I I The a d d i t i o n of the aerated swine waste to the d i g e s t e r s d i d not markedly a f f e c t the amount of COD reduced by the h i g h oxygen treatment. The percentages of COD removed at the 7th and 14th days i n t h i s t e s t were q u i t e s i m i l a r to the percen-tages removed i n Batch Test II and I I I . The medium d i s s o l v e d oxygen l e v e l d i d not remove as much COD as i t had i n the p r e v i o u s batch t e s t s . As a r e s u l t , the amounts removed by the medium and low l e v e l were q u i t e s i m i l a r . The swine waste used i n t h i s batch run was higher i n t o t a l r e s i d u e and averaged 42,615 mg/1 f o r the three d i g e s t e r s as compared to an average of 22,414 mg/1 f o r the two p r e v i o u s t e s t s . 48 At this higher l e v e l of t o t a l residue a larger percen-tage of the COD would be i n a form that would be more d i f f i c u l t to remove by b i o l o g i c a l action. It would appear that the high l e v e l of dissolved oxygen enabled the bio-l o g i c a l culture to remove larger amounts of this less readily oxidizable COD. A least squares li n e a r regression was calculted using the u n f i l t e r e d COD data for the f i r s t six days from the high oxygen treatment and a l l of the data from the medium and low oxygen treatments. This analysis included a l l data over 18,000 mg/1 of COD. The computer li n e a r plots were analyzed s t a t i s t i c a l l y and the slope of the high oxygen plot was found to be d i f f e r e n t from the medium and low oxygen plots at the 1% l e v e l of s i g n i f i c a n c e . The slopes of the plots of the medium and low oxygen plots were not d i f f e r e n t at the 5% l e v e l of s i g n i f i c a n c e . In addition to analyzing the t o t a l COD of the digester contents, analyses were also done to determine the amount of soluble COD i n the digesters each day. This was done by f i l t e r i n g a sample of the digester contents, as outlined i n the section of Materials and Methods, and carrying out a COD analysis on the f i l t e r e d sample. These values are summarized in Table 10. 49 TABLE 10 Batch Test IV  F i l t e r e d COD Determinations (mg/1) D i g e s t e r I II I I I (High 0 2) ' (Low 0 2) (Med. 0 2) I n i t i a l Value 12000 13000 11700 A f t e r 7 days O x i d a t i o n 3560 5800 3780 Percentage Reduction 70.3 55.4 67.7 A f t e r 14 days O x i d a t i o n 2720 4800 3200 Percentage Reduction 77.3 63.1 72.6 The f i l t e r e d COD removed i n c r e a s e d i n a l i n e a r manner with i n c r e a s e s i n the l e v e l of d i s s o l v e d oxygen. This was i n c o n t r a s t to the removal of t o t a l COD where the hig h l e v e l of d i s s o l v e d oxygen removed n e a r l y twice as much t o t a l COD as the medium and low l e v e l . Table 11 shows the f i l t e r e d COD determinations versus time f o r each of the three d i g e s t e r s . During Day 2 there was a r a p i d decrease i n f i l t e r e d COD f o l l o w e d by a slow d e c l i n e over the next 12 days. The hig h removal o f s o l u b l e COD on day 2 was accompanied by a corresponding d e c l i n e i n t o t a l COD at the h i g h and medium oxygen c o n c e n t r a t i o n s but not at the low oxygen c o n c e n t r a t i o n . This would i n d i c a t e that even though about 40% of the f i l t e r e d COD was r a p i d l y removed i n a l l three d i g e s t e r s , i t was onl y being s t o r e d w i t h i n the micro-organisms at the low 0 2 c o n c e n t r a t i o n . T h i s would account f o r the f a c t t h a t 5 0 there was no corresponding decrease i n t o t a l COD. This interpretation i s supported by the works of Robarts (7) who studied the removal of glucose by activated sludge. His studies showed that large amounts of the substrate could be removed and stored within the c e l l and that this storage was separate from the oxidation process. This i n i t i a l decrease i n soluble COD can also be, i n part, attributed to the " I n i t i a l Removal Phase" referred to by Eckenfelder (1). This i n i t i a l removal phase i s used extensively i n waste water treatment i n the form of contact s t a b i l i z a t i o n pro-cesses for activated sludge. In these systems the waste water i s contacted by the b i o l o g i c a l population for a short period of time. During this time the soluble COD is removed by the b i o l o g i c a l population. The micro-organisms are then s e t t l e d and transferred to a digestion tank where the COD that was absorbed or adsorbed by the organisms i s oxidized. In Table 12 the oxygen uptake rates and bacteria counts are shown, for the three levels of dissolved oxygen, at various times during the oxidation period. The bacteria populations for the three levels of dissolved oxygen were unexpectedly uniform throughout the study. The minor changes observed did not correspond to the changes i n oxygen uptake rates of COD removal rates. At the high dissolved oxygen l e v e l the oxygen uptake rates were the highest during the f i r s t three days of the batch run and then gradually decreased. The bacteria count was higher 51 TABLE 11 Batch Test IV COD ANALYSIS (mg/1)* High Oxygen Medium Oxygen Low Oxygen Day T o t a l F i l t e r e d T o t a l ^ ' F i l t e r e d T o t a l F i l t e r e d 0 36000 12000 32120 11700 38600 13000 1 37840 11600 35640 10800 36800 12800 2 31440 5600 28400 6480 35600 6840 3 28800 4840 28200 5040 35400 7160 4 27200 4040 26400 4600 36000 6680 5 24400 5160 24600 4400 32000 6480 6 19600 4200 25000 4800 32600 6800 7 20140 3560 24000 3780 30800 5800 8 22200 3240 26400 3600 29900 5440 9 20000 2940 21200 3120 27600 5400 10 19000 2810 19600 3000 29200 5375 13A 19600 2520 18600 2600 25800 5200 15 19090 2720 20000 3200 26600 4800 * Mean value of two determinations from the same sample. 52 after 5 days and had declined again by day 15. The medium l e v e l of dissolved oxygen did not reach i t s highest rate of oxygen uptake u n t i l the t h i r d day even though i t started with e s s e n t i a l l y the same size of bacteria population as the high oxygen treatment. At the low l e v e l of dissolved oxygen the oxygen uptake rate did not reach i t s highest value u n t i l the f i f t h day and then remained con-stant throughout the batch run. The bacteria l e v e l had actually declined by day 5 and was about the same l e v e l again on day 15. The results indicate that the oxygen uptake rate i s not sole l y dependent on the size of the b i o l o g i c a l population but i s influenced by the metabolic a c t i v i t y of the popula-t i o n . At the high and medium oxygen concentrations the b i o l o g i c a l population appears to be able to remove the substrate and oxidize i t much faster than at the lower oxygen concentration. This high COD removal rate was sustained for only a r e l a t i v e l y short time before a much slower oxidation process took over. Whether a continuous digester could be operated at the high oxygen levels and remove 45% of the COD i n 7 days can not be predicted. The seeding of the digesters did not help the COD removal rates at the medium and espe c i a l l y at the low oxygen concentrations as might have been expected. This would indicate that the l e v e l of dissolved oxygen i n the digesters i s very s i g n i f i c a n t i n determining the rate of oxidation for these concentrated wastes. 53 TABLE 12 Oxyg en Uptake Rates and B a c t e r i a Counts - Batch Test IV I (High 0 2) II (Low o2) I I I (Med. 0 2) DAY 0 2 Uptake mg/l/min. B a c t e r i a count Colonies/ml 0 2 Uptake mg/l/min. B a c t e r i a count 0 2 Uptake mg/l/min. Bac t e r i z count 1 3.2 1380X10 3 .8 1380X10 3 1.3 1440X10 ; 2 3.8 .8 1.8 3 3.0 1.8 3.0 4 1.7 2.0 2.5 5 1.0 2100X10 3 3.0 900X10 3 2.4 1620X10 ! 6 .5 2.5 1.0 7 .7 2.0 1.5 9 .6 2.5 .7 13 .9 3.0 .4 15 .4 1.50.0X1.03 2.5 1000X10 3 .4 1200X10 ; T o t a l o r g a n i c carbon determinations were made on the un-ground, ground and f i l t e r e d contents of the d i g e s t e r s . These values are i n c l u d e d with the t o t a l and f i l t e r e d COD de t e r -minations i n Table XII i n the Appendix. Using these values the COD/TOC r a t i o s were c a l c u l a t e d f o r f i l t e r e d , ground and unground. The d a i l y values f o r these r a t i o s are i n c l u d e d i n Table XIII i n the Appendix and a summary and a n a l y s i s i s shown i n Table 13. The f i l t e r e d COD/TOC r a t i o s p r o v i d e d c o n s i s t e n t r e s u l t s w i t h the means f o r the three d i g e s t e r s being: 2,4, 2.53, and 2.36. The standard d e v i a t i o n of the means f o r t h i s sample treatment were a l s o c o n s i s t e n t i n d i c a t i n g the r e l i a b i l i t y 54 of this measurement. Grinding of the sample before doing the TOC analysis greatly improved i t s r e l i a b i l i t y . This is evident i n the difference between the standard deviation of the means for the ground and unground samples. The t o t a l organic carbon measurements for the ground samples were consistently higher than for the unground samples. This supports the data obtained i n Batch Test III and further indicates that the m i c r o - l i t r e syringe results in an error that gives a lower than true value for high p a r t i c u l a t e wastes. , As a further test of the ef f e c t of sample preparation on TOC measurements, 10 TOC determinations were done on three separate days on the three sample treatments. The values for t o t a l carbon and inorganic carbon were recorded as shown i n Table XIV of the Appendix. A summary and analysis of these values i s given i n Table 14. The analysis i n Table 14 c l e a r l y indicates the increase in accuracy obtained by grinding samples before making TOC determinations. Grinding did not have a marked eff e c t on the accuracy of the inorganic carbon. This was con-sis t e n t with the results obtained i n Batch Test I I I . For t o t a l carbon determinations grinding greatly improved the accuracy as evidenced by a change i n the average standard deviation of the mean from 1214 for the un-ground sample to 116 for the ground sample. 55 TABLE 13 BATCH TEST IV COD/TOC RATIOS AND SAMPLE PREPARATION CODf/TOCf I (High Q 2) I I (Low 0 2) I I I (Med.OQ No. of Determinations 11 11 11 Range 2.04-2.72 1.83-2.89 1.8-2.7 Mean 2.4 2.53 2.36 Standard D e v i a t i o n of Mean .23 .33 .24 COD/TOC No. of Determinations 13 13 13 Range 2.9-4.23 3.06-4.3 3.02-4.1.6 Mean 3.39 3.72 3.58 Standard D e v i a t i o n of Mean .38 .38 .38 COD/TOC No. of Determinations 13 13 13 Range 2.38-3.12 2.73-3.06 2.39-2.95 Mean 2.68 2.87 2.65 Standard D e v i a t i o n of Mean .22 .10 .18 CODf = COD of TOCf = TOC of COD = COD of TOC = TOC of T0C„ = TOC of f i l t e r e d sample f i l t e r e d sample unground sample unground sample ground sample 56 TABLE 14 E f f e c t o f Sample P r e p a r a t i o n on T o t a l Carbon Determinations UNGROUND SAMPLE No. of Determinations Mean mg/1 S.D. T o t a l Carbon  Sample i l l 1 10 10 10 10 10410 9590 9760 1114 652 1848 1152 16 Inorganic Carbon  Sample 2 3 10 10 1105 1411 59.9 36.6 GROUND SAMPLE T o t a l Carbon  Sample L 2 3 No. of Determinations 10 Mean mg/1 12478 S.D. 192 10 10 10 13060 12115 1088 84 70.9 44.9 Inorganic Carbon  Sample 2 3 10 1117 20.6 10 1295 19.7 FILTERED SAMPLE No. of Determinations Mean mg/1 S.D. T o t a l Carbon  Sample 2 3 10 3391 70 10 3627 55 10 2990 65.8 10 975 40.8 Inorganic Carbon  Sample 2 3 10 1145 16 10 1185 15.8 57 The s t a n d a r d d e v i a t i o n o f t h e mean f o r f i l t e r e d s a m p l e s was e v e n l o w e r t h a n t h a t f o r t h e g r o u n d s a m p l e . T h i s i n d i c a t e s t h a t t h e t o t a l o r g a n i c c a r b o n a n a l y s i s c a n be e x p e c t e d t o p r o v i d e good p r e c i s i o n f o r f i l t e r e d o r p r o p e r l y g r o u n d s a m p l e s . 58 GENERAL DISCUSSION The dissolved oxygen concentration had a d e f i n i t e e f f e c t on the COD reduction i n the batch tests. The COD values for Batch Tests II and III i n Table 5 show this e f f e c t with a mean COD reduction of 48.7% after 7 days at the high oxygen l e v e l and a 15.6% reduction at the low oxygen l e v e l . After 14 days the percentage reductions had increased to 57.8% at the high oxygen l e v e l and 38.9% at the low oxygen l e v e l . The changes i n COD with time for the three oxygen treatments for Batch Test II are shown i n Figure 10. The i n i t i a l slow COD reductions at the low and medium 0^  con-centrations appear to be due to a lag phase which occurred for the f i r s t 7 days at the low oxygen and for about 3 days at the medium oxygen concentration. Since the main d i f -ferences i n COD among oxygen levels occurred during the f i r s t 7 days (see Table 5), the data was adjusted to con-sider this i n the best straight l i n e to approximate the data. With this adjustment, COD values were included for the f i r s t 6 days for the high oxygen treatment and for the f i r s t 12 days for the medium oxygen treatment and for the entire oxidation period for the low oxygen treatment. With these l i m i t a t i o n s , a linear regression analysis was made for the reduction of COD with time, combining the results of Batch Tests II and I I I . A s t a t i s t i c a l analysis of the data showed that the slopes of d a i l y COD determinations were found to be d i f -ferent at the 1% l e v e l of si g n i f i c a n c e . These plots are 59 FIGURE 18. A least squares linear regression of COD on time for aerobically digesting swine waste (Batch Test 11 and 111). 6 8 10 12 14 TIME (days) 60 shown i n Figure 18. The lag phase that occurred i n the medium and low dissolved oxygen treatments was not eliminated with the addition of the b i o l o g i c a l culture i n Batch Test IV. In this test the a c t i v i t y of the b i o l o g i c a l culture rather than i t s size was more important i n terms of the amount of COD removed. This a c t i v i t y , as measured by the oxygen uptake rate, was higher at the higher levels of dissolved oxygen. This i n i t i a l removal of f i l t e r e d COD was quite uniform for the three levels of dissolved oxygen. This would i n -dicate that a system designed to remove only the soluble COD should perform s a t i s f a c t o r i l y at the conventional d i s -solved oxygen levels of .5 to 2.0 mg/1. However, the removal of t o t a l COD, as occurs i n an aerobic digester, was greater at the higher levels of dissolved oxygen. The results of this research indicate that the higher levels of dissolved oxygen can improve the e f f i c i e n c y of aerobic s t a b i l i z a t i o n systems. Further work using a con-tinuous feed system are required to f u l l y evaluate the e f f e c t of dissolved oxygen concentration. Figure 19 (high 0 2 digester) i s an example of the changes i n COD and TOC over the 15 day period. The t o t a l organic carbon determinations for the ground samples from the three digesters showed a d i r e c t c o r r e l a t i o n with the values for COD (figure 20). FIGURE 19. Changes i n chemical oxygen demand and t o t a l organic carbon content of swine waste during aerobic s t a b i l i z a t i o n . 4 8 12 TIME (days) €2> FIGURE 20. Least squares simple regression of COD on t o t a l organic carbon content of swine waste (Batch Test IV). 63 A least squares simple regression analysis gives the equations COD = 2.82 TOC - 753 g N = 39 r = 0.95 The high r value indicates that the COD and TOCg have a good c o r r e l a t i o n . This c o r r e l a t i o n i s shown i n Figure 20. A s i m i l a r good c o r r e l a t i o n occurred between COD^ and TOC^ providing the analysis of the raw waste and the analysis on day one were excluded. On both of these days the COD^ to TOC^ r a t i o was s i g n i f i c a n t l y lower than during the rest of the t r i a l having a mean value of 1.91. The reason for this i s not clear but i t was observed that a&much higher percentage of the TOC^ (about 63%) was removed during day two than COD£ (about 45%) . It is possible that the soluble organic carbon compounds which are so read i l y taken up by the microorganisms i n day two and which r e s u l t i n the rapid decline i n the COD^ and TOC^ concentrations have a d i f f e r e n t basic chemical struc-ture from the remaining soluble materials. This could cause a s h i f t from the o r i g i n a l COD^/TOC^ r a t i o to the new more stable r a t i o after the one group of organic compounds i s removed from the mixture. This of course would not a l t e r the COD/TOC ra t i o of the complete sample since this test does not distinguish between dissolved and suspended mate-r i a l s . Figure 21 shows least squares simple regression of 64 COD£ and TOC^ and gives the equation: COD£ = 2.49 TOC f + 150 n = 36 r = 0.93 The i n i t i a l and f i r s t days analysis for C0D £ and T0C £ have been omitted from the data. These results indicate that t o t a l organic carbon determinations can be used to monitor aerobic s t a b i l i z a t i o n processes using high pa r t i c u l a t e waste. The sample var-i a b i l i t y , that has been a source of error with these types of wastes, can be reduced by grinding the sampfes with a glass tissue grinder. 65 FIGURE 2 1 . Least squares simple regression of chemical oxygen demand on to^jQJ organic carbon content of the f i l t e r e d swine waste. TOC f X 1 0 (mg/1) 66 CONCLUSIONS 1. During the batch aerobic s t a b i l i z a t i o n of swine waste, the oxygen concentration does a f f e c t the rate of COD reduction. 2. For the unseeded batch treatment, the rate for COD reduction during the f i r s t 7 days of treatment was highest at high 0 2 (15-20 mg/1) removing 49% of the COD. At the medium oxygen concentration (5-8 mg/1) 351 of the COD was removed after 7 days. The low oxygen digester (0.5 - 1.5 mg/1) had a d e f i n i t e lag phase during the f i r s t 7 days reducing the COD by only 15%. 3. For seeded treatment, the rate of COD reduction was highest at high 0 2 (15-20 mg/1). 4. There is a rapid uptake of organic compounds by the bacteria soon after treatment begins r e s u l t i n g i n a reduction in soluble COD. At high (15-20 mg/1) and medium (5-8 mg/1) 0 2 this uptake of soluble COD is accompanied by a rapid oxidation with accompanying reduction i n Total COD. At low 0 2 (.5-1.5 mg/1) the rapid uptake of organic compounds was followed by a slow steady oxidation process. 5. After about 40% of the o r i g i n a l COD has been removed, the rate of COD removal appears to be less dependent on the oxygen concentration. 6. The Beckman Model 915 Total Carbon Analyzer can be 67 used to determine the t o t a l carbon and inorganic carbon content of swine waste. 7. Grinding the waste i n a tissue grinder before analysis greatly reduces the standard deviation of the mean to t a l carbon content with l i t t l e e f f e c t on the inorganic carbon content. 8. Grinding the waste i n a tissue grinder before sampling with the Hamilton Syringe increases the magnitude of the t o t a l carbon analysis with no s i g n i f i c a n t increase in the inorganic carbon analysis. 9. The TOC determination can be used i n place of the COD determination for evaluation of the strength of the waste during aerobic s t a b i l i z a t i o n . 68 REFERENCES 1. Eckenfelder, W.W.; 1970. WATER QUALITY ENGINEERING, Barnes and Noble, Inc., New York, N.Y. 2. F a i r , M.G., Geyer, J . C , and Okun, D.A.; 1966. WATER AND WASTE WATER ENGINEERING, John Wiley and Sons Inc., New York, N.W. 3. Ford, Davis L.; 1968. APPLICATION OF THE TOTAL CARBON ANALYSER FOR INDUSTRIAL WASTEWATER EVALUATION, Proc. 23rd Indust. Waste Conf., Purdue Univ. Engr. Ext. Ser. No. 132, pp. 989-999. 4. Hiser, L.L.; 1970. A NEW APPROACH TO CONTROLLING BIO-LOGICAL PROCESSES, Environmental Science and Tech-nology. 5. Irgens, R.L. and Day, D.L.; 1966. LABORATORY STUDIES OF AEROBIC STABILIZATION OF SWINE WASTES, J . Agr. Eng. Res. 11, CI) 1-10. 6. Robbins, J.W.D., Kri z , G.J., and Howells, D.H.; TOTAL ORGANIC CARBON DETERMINATIONS ON SWINE WASTE EFFLUENTS, American Society of A g r i c u l t u r a l Engi-neers, Paper No. 69-928. 7. Robarts, R.D. and Kempton, A.G.; 1971. USE OF C1If-GLUCOSE TO STUDY SUBSTRATE REMOVAL BY ACTIVATED SLUDGE, J.W.P.C.F. Vol. 43, No. 8, 1499-1510. 8. American Public Health Association; 1971. STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER, 13th Ed., New York, N.Y. 9. Thabaraj, G.F. and Baudy, A.F.; 1971. EFFECT OF DISSOLVED OXYGEN CONCENTRATIONS ON THE METABOLIC RESPONSE OF COMPLETELY MIXED ACTIVATED SLUDGE, J.W.P.C.F. Vol. 43, No. 2, 318-333. 10. U.S. Department of the Interior; 1970. INVESTIGATIONS OF THE USE OF HIGH PURITY OXYGEN AERATION IN THE CONVEN-TIONAL ACTIVATED SLUDGE PROCESS, W.P.C. Res.Ser. No. 17050VNW05-70. 69 11. Water P o l l u t i o n Control Research Series, 17050DJS05/71. OXYGEN CONSUMPTION IN CONTINUOUS BIOLOGICAL CULTURE, U.S. Environmental Protection Agency. 12. Williams, R.T.; THE CARBONACEOUS ANALYSER AS A WATER POLLUTION RESEARCH TOOL, Preprint Instrument Society of America, 530 Wm. Penn Place, Pittsburgh, Pa. 15219. 70 APPENDIX 71 TABLE I DAY BATCH TEST I COD DETERMINATIONS (mg/1)* I DIGESTER : II II I 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 24,000 23,000 20,352 20,200 20,200 18,650 17,091 17,586 17,529 16,070 15,610 13,566 11,126 11,671 10,657 23,500 22,800 21,744 19,400 19,600 18,650 17,388 16,104 15,138 15,821 11,855 10,149** 10,637 10,229 9,300 24,900 21,900 20,549 20,830 19,400 17,429 16,894 15,412 15,238 13,689 11,361 10,402 9,076 9,457 9,300 * Mean values of two determinations on the same sample ** Day 12 - s i x samples taken from D i g e s t e r II COD d e t e r m i n a t i o n (1) 10,930 (2) 11,126 (3) 10,736 (4) 11,126 (5) 10,930 (6) 10,540 mean 10,898 Value recorded f o r Day 12 10,149 % D e v i a t i o n 6.9 TABLE II DAY COO ave. BATCH TEST I COD REMOVAL REACTION RATES (MOVING AVERAGE ANALYSIS) I CODr CODr COD ave. DIGESTER COD ave. II CODr CODr COD ave. COD ave. I l l CODr CODr COTJiTvc . 1 2 3 4 5 6 7 8 9 10 11 1.2 13 14 22588 20976 20238 19813 18648 1 7605 1 744 8 17179 1 6230 1521.4 13467 118 7 2 1.1281 1162 1537 738 1702 1165 1043 626 517 859 1106 1747 1595 591 .051 .073 .0 36 .086 .062 .059 .0 36 .030 .053 .073 . 1 30 .1.34 .052 22711 21422 20036 19313 1S572 1 7383 16184 15550 14659 12420 1.0670 10*13 10099 614 1289 1386 724 741 1190 1199 6 53 892 2239 1723 285 314 .027 .060 .069 .038 .040 .068 .074 .041 .061 . 180 .161 .027 .031 22512 209 57 20402 19265 17788 166 5 7 15759 14894 13494 11705 10310 9503 9323 1S37 1355 55 5 1138 1454 1086 896 84 5 1400 1791-1393 808 1S2 ,0S2 .06 5 .027 .059 .0S2 .06 5 .057 .057 . 104 .153 .155 .0S5 .020 COD ave. = Average COD CODr = Average COD removed TABLE ITT DAILY MONITORING - BATCH TEST I DISSOLVED 0 2 TEMPERATURE °C 1 pH DAY Digcs ter Pi pester Digcs ter I II III I II III I II III 1 2 45 .15 . 15 15 24 .5 24. 5 24 5 ! 7.55 7.5 5 7 .60 5 00 6.90 6 .80 6 20 26 0 26. 0 26 0 ' 8 00 7.00 7 .00 6 00 27 .0 27. 0 27 o i 2 10 00 ,5.00 .80 30 25 .0 25 0 26 0 8.30 8.30 8.40 11 I 5 5.50 5 .00 5 50 25 .0 25 0 26 0 12 00 5.50 7 .00 6 80 2 5 .0 25 0 25 0 1 20 6.00 ft .00 6 50 26 .0 26 0 26 0 8.30 8.30 8.40 4 00 5. 50 4 . 50 4 00 ' 26 5 26 5 27 0 '• 3 10 on .10 ft .00 6 00 25 5 25. 5 26 0 ' 8.50 8.50 8 . 50 2 30 G.OO (j . 50 4 00 27 .0 27 0 27 0 1 4 10 30 7.30 ft .00 5 50 26 .0 26 0 27 0 i 8.70 8 . 70 S . 70 11 45 3. 50 7 .50 7 50 26 0 26. 0 27 o ; 1 15 7.00 7 .00 7 00 26 0 i -26 0 27 0 4 4 5 6 . 50 7 .00 7 50 27 5 27. 5 28 0 5 0 30 7 . 30 6 .50 6 50 20 .5 25 0 25 0 8.70 8 . 70 8.70 .12 00 7 . 50 5 .50 6 50 24 .0 24 0 24 0 6 9 00 6. 50 6 .50 5 50 22 .0 22 0 23 o 8.80 8.70 8.70 12 00 6. 50 6 .50 6 50 22 0 22 0 23 0 7 7 30 0 7 .00 7 00 22 0 22. 0 22 0 11 15 7.50 8 .00 8 00 22 .0 22 0 22 0 8.80 S. 80 8 .80 1 00 7. 50 8 .00 7 00 22 .5 22 5 23 0 4 00 8.00 8 .00 8 00 - - 22 5 DISSOLVED 0 2 DAY -Digester I II III 8 7: : 30 1. .50 8.00 .50 9; : 30 2 .00 6.00 1 .00 11: :00 . 1. 00 4.00 1 .00 11; :40 3, .00 2.50 .50 12; :45 2, .50 ' 7.50 7. . 50 9 7: : 30 2, .00 8 .00 6. . 50 11: :00 4 . 50 6.50 6 .50 10 7: : 30 5, .00 6.50 7 .00 11 11: :00 8, .00 8. 50 8 .00 12 8: :00 9. .00 9.00 0 .00 1: :00 -4 : 00 -13 9: 00 7. .00 7.00 7. .00 14 9: 00 7, ,50 7.50 8, .00 BATCH TEST I TEMPERATURE "C Digester I II 21.0 21.0 21.0 ' 22.0 22.0 22.0 21.0 21.0 22.0 22.0 21.0 21.0 22.0 22.0 21.5 21.5 23.0 23.0 24.0 24.0 i l l ; I 21.5 j 8.95 22.0 J 22.0 1 21.5 8.90 22.0 , 21.5 | 8.95 22.0 j 21.5 • 8.95 23.5 ; 8.98 24.0 ' 8.90 pll Digester II ' 111 8.95 8.95 8.80 8.90 8.95 8.90 S.95 S.99 8.98 9.03 8.90 8.90 TABLE IV DAY 8: 00 12: 00 1; 00 2: 00 2: 15 3: 15 4: 00 5: 00 6: 00 6: 35 7: 40 7: 00 7 : 45 11: 00 11: 30 2: 30 7: 00 8: 30 9 : 00 11: 00 12 : 30 12: 45 2: 30 7: 00 3: 00 7: 00 8: 00 8: 40 1: 30 3: 30 DAILY MONITORING - BATCH TEST II (DISCONTINUED) D] .JL 10 16 14 16 16 18 15 20 20 19 19 11 17 10 20 18 8 20 16 17 5 16 16 12 17 12 10 20 19 20 ISSOLVED 0 2 II I I I 10 10 20 1.5 17 13 17 13 16 13 14 7 11 4.5 8 4 7.5 1.5 7.5 1.5 6 4.7 1 .5 6.5 .5 4 . 2 14 .2 ! ; J 9 . 5 4 7.5 5 .5 1 6.5 .5 8.5 .5 i 2 i 8 2.5 2.5 12 2 ! 12 . 5 8 1.5 \ 3 1 i 5 1 10 .5 ! 8 .5 14 j .5 j TABLE V DAY I (Low 0 2) COD Total Res .Total 0 32,180 23,160 17, 1 31,300 20,196 14, 2 29,920 20,644 1", 3 29,244 22,764 16, 4 29,616 22,876 17, S 29,212 - -6 28,980 - -7 28,568 22,508 17, 8 24,896 21,632 16, 3 23,316 22,620 17, 10 21,5 38 21,984 16, 1] 20,790 - -12 19,500 - -13 18,750 - -14 17,800 19,996 1", BATCH TEST II ANALYTICAL DATA (mg/1) DIGESTER II (High 0 2 ) V.R. COD Total Res. Total V J 308 30,900 21,992 16,080 396 28,942 21,672 15,596 792 25,608 21,776 15,728 724 23,712 24 ,060 16 ,696 148 20,550 22 ,992 16 ,484 18,420 - -16,530 - -248 15,880 21,132 15,292 060 15,593 19,212 13,748 248 15,61.0 20,200 14 ,440 204 15,016 18,992 13,128 15,236 - -14,500 - -13,500 - -51.6 13,014 18,156 13,016 III (Med. 0 2) COD Total Res_ .Total V. 31,776 21,428 16,128 28,900 2 2,612 16,300 28,518 22,860 15.S29 2S.652 24,440 16,232 27,$60 24,140 16,94 8 25,740 - -22,180 - -21,624 20,948 15,688 20 , 35 2 22 ,000 16,364 20 , 748 21,884 16,320 18,772 20,776 15,59 2 18,810 - -17,500 - -16,750 - -15,886 19.7S0 14,216 TABLE VI DAY BATCH TEST II ' COD REMOVAL REACTION RATES (MOVING AVERAGE ANALYSIS) I (Low 0 2) COD ave. CODr CODr COD ave. DIGESTER n (High o2) COD ave. CODr CODr COD ave. I l l (Meet. 0 2) COD ave. CODr CODr COD ave. 1 2 3 4 5 6 7 8 9 10 11 12 13 31175 30096 29506 29422 29255 28935 27753 2 54 19 23267 21796 26655 19635 18700 785 1079 590 3 36 668 320 1182 2334 2153 14 71 1141 1020 935 .025 .036 .020 .011 .023 .011 .04 3 .092 .093 .067 .04 3 .052 .OSO 28473 25968 23396 20808 184 80 16840 15972 15672 .154 59 15 220 14997 14 4 34 13629 1563 2506 2572 258S 2328 1640 868 301 213 149 443 673 806 .055 .097 . 110 .124 .126 .097 .0 54 .019 .014 .010 .030 . 047 .059 29524 28647 28921 275 28 25375 22931 21445 20769 20155 19276 18473 17640 16722 1534 877 227 89 3 214 R 24 4 9 1486 676 614 SS0 803 833 919 .052 .03.1 .00S .032 .085 .107 . 069 .033 .031 .046 .04 3 .047 .054 COD ave. = Average COD CODr » Average COD removed TABLE VII DAILY MONITORING - BATCH TEST II DAY DISSOLVED 09 . „ I II I I I 3: 30 9.7 10 9.5 4:45 8 15 7 5: 20 8.5 19 6 5: 35 9. 20 6 7:00 2 8 6 8:00 1.5 16 6 9:40 2 2 6 12:15 2 -2 6 12:45 2.5 2 6.5 2:10 1 15 6.5 3: 30 .8 12 .5 11: 20 8 15 2 10:30 7 9 14 11:00 1.5 17 8 4:15 .5 12 4 5:30 2 13 5 6: 00 1 9 3 6: 30 1 13 5 7:00 1 13 5 8 :30 1 12 6 7: 30 2.5 12 5 9:15 2.5 14 7.5 10:45 2.5 15 6.5 12: 30 4 14 4.5 1: 30 2 . 5 15 8 2:45 1.5 17 5.5 3: 30 1.5 17 ! 5.5 9:00 1.5 15 ; 5 11:00 1.5 17 ! 6 12:00 2 18 2.5 1:00 .5 12 8 BATCH TEST II DAY DISSOLVED 0; - I —1  t II 1 2 : 0 0 ; .5 8 12:15i .5 8 12: 30j .5 12 12:40' .5 20 7 : 0 0 ! .5 ' 18 1 1 : 0 0 * 1 . 5 15 1:30 1 . 0 15 1 0 : 0 0 2 . 0 14 2 : 0 0 1.5 15 1 1 : 0 0 1.5 16 1: 30 1 . 2 18 7 : 0 0 1 . 0 19 3: 30 1 . 5 18 1 2 : 0 0 1 . 2 i 18 4 : 0 0 1.3 i 1 8 7 : 0 0 1.5 ! 1 9 1 1 : 0 0 1 . 0 . 15 7:30 1 . 5 ; 19 I I I I 5 4 5 6 5 5 6 5 5 6 6 6 5 5 5 5 8 5 5 TABLE VIII BATCH TEST III ANALYTICAL DATA (mg/1) DIGESTER I (Low 0 2) II (High 0 2) III (Med. 0 2) COD TOTAL RES. .TOTAL V.R. COD TOTAL RES .TOTAL V.R. con TOTAL RES .TOTAL V.l 0 30,896 22,961 17,068 30,313 21,138 15,692 30,993 21,804 16,044 1 30,37 3 - - 28,855 - - 29,139 - -2 29,911 22,070 16,094 28,614 21,058 15,192 29,283 21,426 15,514 3 30,315 - - 25,243 - - 2 7,657 - -4 29,478 22,966 16,642 23,469 21,826 15,654 26,139 22,626 16,156 5 28,730 - - 18,740 - - 22,030 - -6 26,900 2 2,158 16,530 16,900 18,350 12,768 19,300 22,716 16,506 7 24,645 - - 15,256 - - .18,972 - -0 24,963 22.3S2 16,730 13,461 16 ,5 86 11,490 ,14,8 24 20,294 14, 776 9 24,6 33 - - 13,811 - - 15,745 - -10 26,656 22,698 16,630 14 ,014 16,000 10 ,476 15 ,756 18 , 4 22' 12,890 11 24,996 - - 13,041 - - 15,61.0 - -12 23,608 19,734 15,314 13,132 15,862 10 ,570 1.4 ,896 17,848 12,664 13 22,500 ' - - - " - - 15,000 - -14 20,730 18,788 13,444 12,616 15 ,779 10,572 15,061 17,595 12,340 CO o TABLE IX BATCH TEST III COD REMOVAL REACTION RATES (MOVING AVERAGE ANALYSIS) DAY COD ave. I (Low 0 2) CODr CODr COD ave. COD ave. DIGESTER II (High 0 CODr ) CODr COD ave. COD ave. I l l CODr (Med. 0 2) CODr COD ave. 1 29,159 789 .027 29 ,639 889 .030 30,38 8 377 .012 2 27,832 1 ,328 .048 28,841 797 .028 30 ,128 261 . 009 3 2 5 , 64 2 2,189 .085 27 ,684 1, 157 .042 30,00 5 123 .004 4 22 ,730 2,912 .128 25,991 2, 19 3 .0 86 29 ,500 50 5 .04 7 5 19,462 3,26 8 .168 22,375 3, 117 . 139 28,460 1,041 .0 37 0 16,447 2,513 . 153 20,151 2, 474 .123 26,794 1,158 .045 7 15,218 1,731. .114 18,017 1, 8S4 . 105 . 25.2S8 1,665 .066 8 13 ,997 1,221 .087 16,091 1, 926 .120 24 , 801 805 .033 9 13,774 311 .023 15,518 2, 295 .148 25,221 - -10 13,7 20 54 .004 15,717 - - 25,735 - -11 .' 13,307 413 .031 15,468 249 .016 25,604 67l' .0 26 12 13,076 231 .018 15,100 368 .024 23,678 1,386 .0 59 13 12,937 139 .011 14 ,989 111 .007 2 2,335 1,344 .060 COD ave. = 3 Day Average COD CODr = Average COD removed 00 TABLE X DAILY MONITORING - BATCH TEST I I I JAY DISSOLVED 0 2 TEMPERATURE I TT I I I I I I I I I 3 :50 9 . 7 10 9.5 22 22 22 •1 : 4 5 S.O 15 7.0 5 : 20 8 . 5 19 6.0 23 23 23 5 : 35 9.0 20 6 7 :00 2.0 8 : 6 S :00 2.0 10 6 i 9 :00 1.5 2' 6 22 22 22 12 : 15 ' 2.0 2 6 23 23 23 12 : 4 5 2 . 5 15 6.5 2 : 10 1.0 12 6 . 5 23 23 23 3 : 30 . S 12 . 5 24 24 24 11 : 20 S.O 15 2.0 10 : 50 7.0 9 14 23 23 23 J 1 :00 1.5 17 S 11 :15 . 5 12 7 3 : 50 .5 15 12 25 27 27 5 : 30 Z 13 5 6 :00 1 9 3 6 : 50 1 13 5 7 :00 1 .1 3 5 8 : 50 1 12 6 7: : 50 2 . 5 .12 5 22 23 23 0 :15 2 . S 14 7.5 22 23 23 10 :45 2 . 5 15 6.5 12 : 50 4 .0 1.4 4.5 23 24 24 1 : 50 2 . 5 1.5 8 ? ; : 4 5 1.5 17 5.5 3: : 50 1 . 5 17 5.5 8 : 00 1 . 5 15 5 11 : 00 5 . 5 17 6 24 2 5 24 12 : 00 2 . 18 2.5 1: :00 . 5 12 8 2 ; : 50 1 . 5 19 8 12: :00 . 5 8 5 24 24 24 12: :15 . . 5 8 5.5 12: :30 i . 5 1.2 | 4.0 I ! ! 12: :40 1 20 8 I 1 1 pH I I I I I 3.1 8.1 8.2 8.2 8.2 8.2 8.2 1.3 8.4 I DAY DISSOLVED 0 2 I II III I 7 10 00 1.5 18 7 26 11 00 1.5 18 4 8 10 00 . 5 19 2 11 30 1.5 12 4.5 25 1 15 2. , 11 4.5 3 4 5 l i s ] 2 5 s 00 2 15 5 9 S 00 4 20 5 24 9 30 3 20 5 10 40 4 18 6 1.1 .1.5 ? 17 5 11 4 5 1.5 1 9 6 1 00 3 19 2 1 30 1 20 6 ? 45 2 20 2.5 24 10 S 00 3.5 6 4 9 30 1 20 6 11 00 1 20 6 12 30 2 20 6.5 2 00 1.5 20 3 5 00 1.5 16 7.5 11 8 00 4 16 5 23 9 30 2 16 2 10 00 1.5 19 6 1 00 1.5 16 5.5 12 8 30 1 20 5 10 30 1 20 4 13 12 30 1 20 5 14 12 30 1.5 20 8 15 12 30 2.5 20 7.5 • 22 TEST i n TEMPERATURE pH II III .1 ; II 1 III 25 25 8.4 8.6 8.7 24 24 8.4 8.7 8.7 24 24 8.5 8.7 , 8.8 24 24 8.5 8 . 7 '! 8.8 23 23 ; . 8.5 8.9 1 8.9 22 23 8.6 ' 9.0 8.9 TEST III Tot I Carbon, TABLE XI Inorganic Carhon and Sample ['reparation SUPERNATANT FROM SETTLED FOR 10 MINUTES I High 0 2 II Med. 0 2 III Low 0 2 DAY TOTAL C IN.C ORG.C TOTAL C IN.C ORG. C TOTAL C IN.C ORG.C 0 8500 1000 7 500 8500 1000 7500 8500 1000 7500 2 7900 900 7000 8500 900 7600 8500 700 7800 4 7100 1500 5500 8000 1100 6900 8200 600 7400 6 5100 1200 3900 5200 1000 4200 7100 600 5500 8 4900 1300 3600 5000 1300 3700 7500 700 6S00 10 3500 1300 2 200 3900 1300 2600 7900 800 7100 12 4200 1200 3000 4100 1500 2600 6700 900 5800 14 3900 1200 2700 4000 1600 GROUND 2400 6300 1000 5500 0 11000 900 10100 10300 900 9400 10400' 900 9500 2 9300 1000 8 300 10100 900 9200 10000 900 9100 4 9200 2400 680 0 9500 1000 8500 10200 700 9500 6 74 00 1000 6400 7500 1000 6500 8S00 700 S100 8 6900 1400 5 50 0 7100 1400 5700 9800 700 9100 10 5100 1300 . 38(10 5500 1400 4100 8100 800 7300 12 6000 1300 4700 7100 1500 5600 8600 SOO 7S00 14 6000 1300 4700 6300 1500 UNGROUND 4800 8000 1000 7000 0 9400 900 8500 9600 900 8700 9400 900 8500 2 8700 700 8000 10000 900 9100 10400 700 9700 4 8600 1400 7 200 8900 1000 7900 9200 600 8600 6 6300 1200 5100 ; 7500 1200 6300 S900 700 8200 8 4900 1400 3500 4900 1200 3700 7800 700 7100 10 5000 1500 3500 5600 1500 4100 7900 800 7100 12 5000 1300 3700 5300 1500 5800 '7300 i SOO 6500 14 4900 1500 3400'. 5600 isoq 4100 7000 900 6100 TABLE XII COD AMD TOC DETERMINATION'S-BATCH TEST IV DAY Digester I (High Oxygen) COD ( f i I t e r ) COD TOC ( f i l t e r ) TOC 85 TOC ground 0 12000 56000 5100 12000 13000 1 11600 37840 5700 1 2200 13400 2 5600 51440 2150 10000 11300 3 4840 28800 2350 9S00 10200 4 4040 27200 1730 8300 10850 5 5160 24400 1900 7000 8800 6 4200 19600 1930 6750 8850 7 3560 20140 1500 5800 8450 8 3240 22200 1300 6500 8250 9 2940 20000 1100 57 50 7050 10 2810 19000 1075 4850 7050 13 2520 19600 1010 5470 7120 15 2720 19040 1110 4500 6100 Digester II (Low Oxygen) 0 13000 38600 7500 12600 14000 1 12800 36800 7000 12000 1 3500 2 6840 35600 2400 10600 12000 5 7160 35400 2500 9600 12000 4 66S0 76000 24 50 9500 12600 5 6480 32000 27 50 8400 11000 6 6800 32600 2700 8600 11600 7 5800 30800 2550 7800 11 200 8 5460 29900 2050 7600 10100 9 • 5400 27600 2000 7400 9500 10 • 5375 29200 1900 7801 10100 13 5200 25800 1S00 6000 9200 15 4600 26600 2100 6300 8700 Digester III (Medium Oxygen) 0 11200 32120 6500 9200 11800 1 10800 35640 6000 9600 12600 -> 64S0 284 00 2400 9400 11600 3 5040 28200 2400 9000 11000 4 4600 26400 1800 S400 10800 5 4400 24600 1900 - 9600 6 4800 25000 2000 ' 7200 9200 7 3780 24000 1700 • 6200 S600 8 5600 26400 1500 . 6400 9200 9 3120 21200 1200 5610 S400 10 3000 19600 1200 5200 8200 13 2600 18600 1100 • 5600 7000 15 3200 20000 1300 4800 6800 86 TABLE XIII COD/TOC RATIOS - BATCH TEST IV DAY 0 1 2 3 4 5 6 7 8 9 10 13 15 0 1 2 3 4 5 6 7 8 9 10 13 15 DIGESTER I (High 0 2) CODf/TOCf 04 61 06 34 72 18 37 ,49 67 COD/TOC 3, 3 3 3 3 3 2 3 3 00 10 14 03 27 49 90 47 52 COD/TOC 2.50 2.45 3.47 3.91 3.58 4.23 2. 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 77 82 78 67 50 77 21 38 69 83 69 66 12 DIGESTER II (Low 0 2) 1, 2, 2, 2, 2 2, 2 2 2 2 2 833 85 86 73 36 52 27 65 70 89 19 06 07 36 69 78 81 79 95 93 73 ,74 ,30 ,22 2. 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 3, 76 73 97 95 86 91 81 75 96 91 92 80 06 DIGESTER III (MEDIUM 0 2) 0 ! — 3.49 2.72 1„ ! 1.80 3.71 2.83 2 ! 2.70 3.02: 2.45 3 2.10 3.13 ! 2.56 4 i 2*55 3.14 j 2.44 5 i 2.32 t 1 2.56 6 : 2.40 3.47 | 2.71 7 i 2.22 3.87 2.79 8 \ 2.40 4.13 2.87 9 2.60 3.79 j 2.52 10 - 3.77 ; 2.39 13 ( 2.36 3.32 j 2.65 15 2.46 4.16 i 2.94 CODf = f i l t e r e d COD TOCf = f i l t e r e d TOC TOC.g = ground TOC 87 TABLE XIV Batch Run IV Total Carbon and Inorganic Carbon Values FILTERED GROUND UNGROUND T.C. i.e. T.C. i.e. T.C. i.e. 3400 3300 3500 3400 3300 3400 3500 3400 3400 3300 1000 1000 1000 1000 .V975 900 1000 975 900 1000 13000 12700 12800 12700 12500 12200 12700 12700 12500 12400 1100 975 1100 1100 1150 1125 1110 1050 1100 1125 10500 10500 11200 10000 10700 10700 | 9200 10700 9500 11100 1125 1100 1100 1125 1110 1100 1150 1125 1100 1110 3500 3650 3650 3550 3650 3660 3650 3660 3650 3650 1150 1150 1175 1150 1150 1175 1150 1125 1150 1175 13000 13100 13200 13100 13000 13000 13000 13000 13000 13200 1100 1100 1150 1100 1125 1100 1125 1150 1100 1125 9200 11000 6800 10800 10200 6400 10600 10000 8700 12200 1150 1150 1000 1100 1150 1150 1100 1000 1150 1100 3050 3050 3000 3000 2900 2900 3050 3000 3050 2900 1170 1170 1170 1200 1200 1200 1170 1200 1200 1170 12200 12150 12150 12050 12000 ! 12150 | 12200 ! 12050 12050 12150 1325 1300 1275 1275 1300 1275 1325 1300 1275 1275 9700 8700 9700 8500 12300 9500 8600 9700 10000 10900 1450 1400 1450 1380 1350 1400 1450 1380 1400 1450 Day 2 

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