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The effect of primary and secondary sludge mix ratios on VFA production in thermophilic aerobic digestion.. Fothergill, Samantha 1996

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THE EFFECT OF PRIMARY AND SECONDARY SLUDGE MIX RATIOS ON VFA PRODUCTION IN THERMOPHILIC AEROBIC DIGESTION USING PILOT SCALE ATAD UNITS  by  SAMANTHA FOTHERGILL B.Eng., McGill University, 1994  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES Department of Civil Engineering  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA 1996 ©Samantha Fothergill, 1996  In presenting  this thesis in partial fulfilment of the requirements  for an advanced  degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. copying  I further agree that permission for extensive  of this thesis for scholarly purposes may be granted  department  or  by  his  or  her  representatives.  It  is  by the head of my  understood  that  copying  or  publication of this thesis for financial gain shall not be allowed without my written permission.  ;  Department of -..<2.-l\J\i-  <s= *4.<^• ^&<&g_i  The University of British Columbia Vancouver, Canada Date  DE-6 (2788)  <Z>CZ-T 2 - 4  /  5fo  G>-  ABSTRACT  Research was undertaken to determine if a mixture primary and secondary sludge could provide increased volatile fatty acid (VFA) production, as compared with primary sludge alone, in a thermophilic aerobic digestion process. In addition, pre-solubilization of the secondary sludge, with NaOH, was investigated for its effect on VFA production. Previous research has demonstrated that VFA production can be enhanced during the thermophilic digestion of primary sludge with reduction in both aeration and retention time. Secondary sludge was predicted to further enhance production by providing the required substrate for process micro-organisms 'pre-packages' in the correct ratios. Pre-solubilization of the secondary sludge was intended to make this substrate readily available to process micro-organisms, eliminating a potentially rate-limiting step. Pre-solubilization of feed sludge has been shown to enhance anaerobic digestion.  Experiments were carried out at UBC's Wastewater Treatment Pilot Plant. Primary and secondary (Bio-P) sludges were generated on-site, by a modified UCT process, and metered to feeding tanks daily for use in the autothermal thermophilic aerobic digestion (ATAD) reactors. Configured in parallel, the two, 125 L reactors were each operated asfirststage reactors, in semi-continuous mode, with an average retention time of 3 days. Based on TS, primary/secondary mix sludge ratios of 100/0, 65/35, 35/65, and 0/100 were tested in parallel with primary sludge in the control reactor. The 35/65 and 0/100 streams were additionally pre-solubilized, with 15 meq/L of NaOH, and tested in parallel with non-solubilized mix ratios of 35/65 and 0/100, respectively, in the control reactor. Through all experimental runs: feed consistency was maintained around 1% TS; reactor temperatures stayed between 42°C to 50°C, ie. within the thermophilic range; and a "micro-aerobic" environment was sustained with a constant supply of air into the reactor contents (< 1 mg/L DO, and consistent ORP values between -200 mV and -450 mV). ii  The incorporation of secondary sludge, in mixed sludge feed, resulted in increased production and accumulation of VFA. The greatest production and accumulation of VFA was produced with the digestion of 100% secondary sludge. Although chemical pre-solubilization of sludge resulted in increases in VFA concentrations in the feed tanks, no conclusions could be made with respect to its efFect on VFA production in ATAD. The addition of NaOH did produce largefluctuationsin reactor pH. Based on this impact on digester stability, and the positive results obtained without chemical pre-solubilization of feed sludge, further investigations were not undertaken with NaOH. Analysis of nutrient species confirmed that, both the mixing of primary and secondary sludge, and further, the thermophilic aerobic digestion of mixed and secondary sludges, results in the release of stored phosphorus and increases in ammonia nitrogen. Post-treatment, of some type, would be required before recycle to nutrient removal processes.  iii  TABLE OF CONTENTS  ABSTRACT  < .  ii  LIST OF TABLES  vi  LIST OF FIGURES  vii  LIST OF APPENDICES  viii  ACKNOWLEDGEMENTS . . .  ix  1.0 INTRODUCTION 1.2 Project Objectives  1 2  2.0 LITERATURE REVIEW 2.1 Thermophilic Aerobic Digestion 2.1.1 Process Description 2.1.2 Facilities in North America 2.2 Volatile Fatty Acids 2.3 Volatile Fatty Acids in Therophilic Aerobic Digestion 2.3.1 Detection 2.3.2 Theory of Production 2.3.3. Effects of Operating Conditions 2.3.3.1 Temperature 2.3.3.2 Aeration 2.3.3.3 Retention Time 2.3.3.4 Feed Sludge 2.3.3.5 Pre-Solubilization  3 3 4 6 8 10 10 11 13 14 16 18 20 22  3.0 METHODS AND MATERIALS 3.1 Experimental Set-Up 3.1.1 Sludge Source 3.1.2 ATAD Reactors 3.1.3 Retention Time 3.1.4 Mixing and Aeration 3.2 Monitoring Variables 3.2.1 Temperature 3.2.2 Turborator™ Speed 3.2.3 ORP 3.2.4 Dissolved Oxygen 3.2.5 Airflow 3.2.6 Air Composition 3.2.7 pH 3.2.8 Total Solids 3.3 Experimental Variables 3.3.1 Volatile Fatty Acids  23 23 25 28 28 29 31 31 31 32 32 33 35 35 35 36 36 iv  3.3.2 Nitrogen and Phosphorus 3.3.3 Total Organic Carbon 3.4 Sampling Points 3.5 Interpretation of Results  38 39 40 41  4.0 RESULTS AND DISCUSSION 4.1 Experimental Set-up 4.2 Operating Conditions 4.2.1 Source Sludge 4.2.2 Temperature 4.2.3 Turborator™ Speed 4.2.4 ORP 4.2.5 Dissolved Oxygen 4.2.6 Airflow 4.2.7 Air Composition 4.2.8 pH 4.2.9 Feed Total Solids 4.3 Total Solids Destruction 4.4 VFA Production - Mixed Sludge Ratio Runs 4.4.1 Feed Streams 4.4.2 AT AD VFA Production 4.5 VFA Production - Pre-solubilization Runs 4.5.1 Feed Streams 4.5.2 ATAD VFA Production 4.6 VFA Production-Run Inconsistency 4.7 VFA Speciation 4.8 Nutrients 4.8.1 Phosphorus 4.8.2 Nitrogen 4.9 Total Organic Carbon  42 42 43 43 48 53 55 61 61 63 65 68 70 73 73 75 80 80 83 86 89 9  2  9  2  9  5  9  8  1  0  0  1  0  0  5.0 SUMMARY 5.1 Operating Conditions 5.2 Enhancement of VFA Production 5.3 Pre-Solubilization 5.4 Nutrients 5.5 Phosphorus Release Mitigation 5.6 Alternative Applications  103 1°4  6.0 CONCLUSIONS AND RECOMMENDATIONS  105  REFERENCES  1  0  7  APPENDICES :  1  1  3  101  v  1  0  2  1  0  2  LIST OF TABLES TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE TABLE  2.1: VOLATILE FATTY ACID SPECIES 2.2: TYPICAL TAD OPERATING TEMPERATURES 3.1: EXPERIMENTAL DESIGN 4.1: EXPERIMENTAL TIMETABLE 4.2: CHARACTERISTICS OF SOURCE SLUDGE 4.3: AVERAGE ATAD TEMPERATURE 4.4: AVERAGED ATAD ORP 4.5: AVERAGE AIRFLOWS 4.6: AVERAGE ATAD pH 4.7: AVERAGE FEED TOTAL SOLIDS 4.8: TOTAL SOLIDS DESTRUCTION EFFICIENCY 4.9: AIRFLOW EFFECTS ON VFA ACCUMULATION 4.10: VFA SPECIATION IN FEED SLUDGE 4.11: VFA SPECIATION IN ATAD  vi  8 16 25 42 44 52 59 62 65 69 70 80 91 91  LIST OF FIGURES FIGURE 2.1: Location of ATAD Facilities in North America FIGURE 2.2: Model of Enhanced Biological Phosphorus Removal FIGURE 2.3: Temperature Effect of Changes in Turborator™ Speed FIGURE 3.1: Process Flow Diagram of the UBC Pilot Plant FIGURE 3.2: Process Flow Diagram of Experimental ATAD Set-up FIGURE 3.3: Air Flow Meter Set-up FIGURE 3.4: Air Flow Calibration Curves FIGURE 4.1: Source Sludge TP FIGURE 4.2: Source Sludge P 0 FIGURE 4.3: Source Sludge N H FIGURE 4.4: Source Sludge VFA FIGURE 4.5: ATAD Temperature Profile, Run 1 . , FIGURE 4.6: ATAD Temperature Profile, Run 2 FIGURE 4.7: ATAD Temperature Profile, Run 3 FIGURE 4.8: ATAD Temperature Profile, Run 4 FIGURE 4.9: ATAD Temperature Profile, Run 5 FIGURE 4.10: ATAD Temperature Profile, Run 6 FIGURE 4.11: Turborator™ Speed FIGURE 4.12: ATAD ORP Profile, Run 1 FIGURE 4.13: ATAD ORP Profile, Run 2 FIGURE 4.14: ATAD ORP Profile, Run 3 FIGURE 4.15: ATAD ORP Profile, Run 4 FIGURE 4.16: ATAD ORP Profile, Run 5 FIGURE 4.17: ATAD ORP Profile, Run 6 FIGURE 4.18: Effect of Increased Additions of Secondary Sludge on ORP FIGURE 4.19: Shark Tooth Pattern of ORP in Response to Substrate Addition in ATAD FIGURE 4.20: ATAD Air Composition FIGURE 4.21: pH Instability with Pre-solubilization of Feed Sludge FIGURE 4.22: Total Solids Feed Variability FIGURE 4.23: VFA in Feed, Runs 1 to 4 FIGURE 4.24: Net VFA Production in ATAD, Runs 1 to 4 FIGURE 4.25: ATAD VFA Accumulation as a result of Mixed Sludge Feed FIGURE 4.26: VFA Feed Variability, Runs 5 & 6 FIGURE 4.27: Net VFA Production, Runs 5 & 6 FIGURE 4.28: ATAD VFA Accumulation as a Result of Pre-solubilization FIGURE 4.29: Run Inconsistency with 100% Secondary Sludge FIGURE 4.30: Run Inconsistency with 35/65 Mix Sludge Ratio FIGURE 4.31: Fate of Ortho-Phosphate FIGURE 4.32: Solubilization of Phosphorus, TP FIGURE 4.33: Fate of Nitrogen, Ammonia FIGURE 4.34: Solubilization of Nitrogen, TKN FIGURE 4.35: Averaged TOC FIGURE B l : UBC Pilot Plant Facility FIGURE B2: Raw Sewage Storage Tanks FIGURE B3: Sludge Feed Tanks for ATAD Reactors with mixers FIGURE B4: ATAD Reactors with Turborator™ Mixing/Aeration Device FIGURE B5: ATAD Reactor Lid 4  4  vii  7 9 15 24 27 30 34 46 46 47 47 49 49 50 50 51 51 54 56 56 57 57 58 58 60 60 64 67 68 74 76 78 82 84 85 87 87 94 94 97 97 99 B-2 B-2 B -3 B-4 B -5  LIST OF APPENDICES APPENDIX A: ABBREVIATIONS APPENDIX B: PHOTOS APPENDIX C: OPERATING DAT A APPENDIX D: AIRFLOW AND AIR COMPOSITION DATA APPENDIX E: TOTAL SOLIDS AND SOLIDS DESTRUCTION DATA APPENDIX F: VFA DATA APPENDIX G: NUTRIENT DATA APPENDIX H: TOC DATA APPENDIX J: FORMULAS & SAMPLE CALCULATIONS APPENDLXK: STATISTICS TABLES  viii  ACKNOWLEDGEMENTS I would like to acknowledge the following individuals for their contributions to the completion of this work and my Masters degree: •For initiating and funding the research project, I would like to thank my advisor at UBC, Don S.Mavinic. In addition, I would like to express my appreciation for encouraging me to attend conferences and present my work to others. •For his speedy review of my thesis, Victor Lo, Bio-Resource Engineering, UBC. •For their technical support and expertise, I would like to thank Jufong Zhu, Paula Naylor and Susan Harper in TJBC's Environmental Engineering Laboratory. •For their guidance at the pilot plant, I would like to thank Angus Chu, now Dr. Chu, and Fred Koch, the "keeper of the plant". I could not have asked for two more knowledgable and opinionated people to bounce my ideas off of. •I would like to thank Guy Kirsch and Scott Jackson for their time and additionally, for their interest, when responding to my mechanical and electrical problems. • For assisting in the tedious task of data entry, providing a substitute to cycling to the plant late at night, looking after the reactors and being there when I came home late at night, I would like to thank Jim Hughes. May I be able to return half the favours. •For her assistance in operating the plant and preparing lab samples, I would like to thank Tina Ragona. Your company in the lab made the long hours alot more enjoyable. • For getting me tofinallyfinishand helping with all the printing & copying, I would like to thank Stephen Craddock. •Finally, to my roomates, friends and family, a huge thank-you for putting up with me (especially during the experimental period), listening to me ramble about my project and keeping me in touch with reality through it all.  ix  1.0 INTRODUCTION  Volatile fatty acids (VFA) are one of many carbon substrates utilized by micro-organisms in nutrient removal in wastewater treatment. Although naturally present in wastewater, levels are variable and result in inconsistent removal. The principle of producing additional VFA to supplement processes has been developed and widely applied using fermenters. Although VFA have been detected in thermophilic aerobic digestion units, the use of the effluent for this same purpose has not been as extensively investigated, nor applied.  Since its inital development in Germany in the 1960's, autothermal thermophilic aerobic digestion (ATAD) has been investigated for its suitability in numerous applications around the world. Research of thermophilic aerobic digestion has focused on process kinetics, stabilization and pasteurization capabilities, and pre-conditioning benefits for mesophilic anaerobic digestion. Researchers in Canada have investigated many of these aspects and additionally have initiated research into enhancing the accumulation of VFA, a by-product of the process, for the benefit of Bio-P wastewater treatment processes.  The produciton of VFA in thermophilic aerobic digestion is theorized to be the result of both oxidation and fermentation reactions which are co-established as a result of the oxygen restricted environment. The net accumulation of VFA has been theorized to be the result of inhibiton of their degradation, the uncoupling of oxidation and non-oxidation phases of metabolism, and the combination of these and other alterations to bio-chemical pathways^  This thesis investigated the effect of raw secondary sludge and pre-solubilization of secondary sludge on VFA production. Secondary sludge was predicted to potentially increase VFA concentrations as 1  a result of improved treatment effeciency in thermophilic aerobic digestion.  Specifically, by  supplying biomass as substrate, process micro-organisms are provided with the necessary components for aerobic bio-oxidation "pre-packaged" in the correct ratios. In addition, fermentation mechanisms may also be enhanced with increases in treatment efficiency.  Moreover, pre-solubilization of  secondary sludge feed could make this "ideal" substrate directly available to process microorganism and assumedly further enhance treatment efficiency and VFA production. In the past, presolubilization has been demonstrated to enhance anaerobic digestion and the formation of by-products (Knezevic, 1993).  1.2 Project Objectives  Utilizing the pilot scale ATAD units and wastewater treatment facilities at UBC, experiments were designed to:  (a) determine if a mixture of primary and secondary sludge can provide increased VFA production in thermophilic aerobic digestion, as compared to primary sludge alone;  (b) determine if pre-solubilization of secondary sludge enhances VFA production in thermophilic aerobic digestion;  (c) evaluate the effects of secondary sludge addition and pre-solubilization on "nutrient fate" and treatment efficiency in thermophilic aerobic digestion.  2  2.0 LITERATURE REVIEW  The production of volatile fatty acids (VFA) in thermophilic aerobic digestion was detected in early development and application of the process. Investigations into the mechanisms of VFA production and dedicated generation is only more recent. Before presenting a detailed summary of this research, a brief description of the thermophilic aerobic digestion process is provided, along with an overview of VFA utility in wastewater treatment.  2.1 Thermophilic Aerobic Digestion  Autothermal thermophilic aerobic digestion, ATAD, is the name and acronym coined for the aerobic digestion of sewage sludges at elevated temperatures without the application of external heat sources. The energy generated in the bio-oxidation of substrate is conserved as heat within the system, elevating reactor temperatures to greater than 40°C. Interchangeably, TAD, thermophilic aerobic digestion, also refers to this same process; the use of "autothermal" in the process description is debatable based on the high energy inputs required for efficient mixing and aeration. In addition, some facilities use additional heat sources. In this paper, TAD will be used to refer generally to thermophilic aerobic digestion, while ATAD will more specifically refer to systems known to rely solely on biologically generated heat, mixing and aeration to attain desired temperatures, ie. the UBC pilot plant reactors. TAD, like other digestion processes, is designed to stabilize sludge through the reduction of volatile solids, but additionally provides the temperatures required for regulatory pasteurization.  Thermophilic aerobic digestion is also used as a pre-treatment step for mesophilic anaerobic digestion. The thermophilic temperatures during aerobic thermophilic pretreatment (ATP) provide the necessary 3  environment for pasteurization that are absent with mesophilic anaerobic treatment, while at the same time supplementing volatile solids destruction to reduce overall treatment time (Hamer & Zwiefelhofer, 1985; Langeland et al., 1985). ATP has also been demonstrated to enhance anaerobic digester performance with respect to:  • improved stability of process due to consistent feed (Appleton &Venosa, 1986b) • improved bio-gas production (Baier & Zwiefelhofer, 1991) • reduced, to complete elimination, of heating requirements (Fuggle & Spensley, 1985) • reduced requirements for buffering chemicals (Appleton & Venosa, 1986b) • reduced foaming due to control oiNocardia (Pagilla et al., 1995), • elimination of competitive micro-organisms (Sonneleitner & Fiechter, 1983),  Dual digestion, as this combined treatment is referred to, has been extensively employed in the expansion and upgrade of existing facilities equipped with mesophilic anaerobic digesters (Baier & Zwiefelhofer, 1991).  2.1.1 Process Description  Thermophilic aerobic digestion systems can be either single or multi-stage.  As thermophilic  organisms build-up spontaneously with an increase in temperature (Sonnleitner & Fiechter, 1985), systems operate without sludge recycle and can be operated in batch, semi-continuous or continuous mode. Multi-stage facilities, with batch or semi-continuous operations, are the most common as they ensure a minimum retention times for regulatory degree-day specification for pathogen elimination ( Langeland et al., 1984; Strauch et al, 1985; Deeney et al., 1991).  4  Key components of the ATAD include adequate biodegradable matter for the aerobic microorganisms to generate heat (> 2.5% VS), a well-insulated reactor to contain the heat and allow elevation of reactor temperature, and efficient aeration and mixing equipment to facilitate high oxygen transfer efficiency without excesses heat losses in off-gases (Fuggle & Spensley, 1985; Hamer & Zwiefelhofer, 1985; Vismara, 1985; Deeney et al, 1991). Both aspirating, and pump and venturi systems, using air or oxygen, have been successfully applied in ATAD. Retention time is also critical in ATAD, see Section 2.3.3.3.  The main advantages sited for the use of thermophilic aerobic digestion systems are reduced reactor volumes and/or retention times as a result of increased biological rates, and simultaneous production of a pasteurized sludge. Specifically, in comparison to a mesophilic anaerobic digestion reactor, volumes are approximately 1/4 the size (Kelly et al, 1995), and in comparison to composting, lime conditioning and extended aeration for pasteurization, treatment times are reducedfrommonths to days (Murray et al., 1990). In addition, thermophilic aerobic digestion is a flexible and stable process which is simple to operate and maintain. The main draw-back of the ATAD system is the high energy inputs required for mixing and aeration (Bruce & Oliver, 1987).  Originally developed in Germany as an alternative digestion treatment to meet new land disposal regulations, the thermophilic aerobic digestion process has been adapted world wide for various applicatons. Burnett (1995) and Deeney et al. (1991) provide excellent overviews of ATAD systems in Europe and Canada. With respect to economics, ATAD is generally limited to small and medium sized facilities; in larger facilities, anaerobic digestion is still favoured for energy recovery through methane production (Wolf, 1982).  5  2.1.2 Facilities in North America  In 1990, the ATAD process was introduced to North America in Banff, Alberta, while at the same time pilot scale reactors were added to the wastewater treatment plant on UBC's campus for research. Since this initial introduction, other research facilities and full scale plants have been constructed across North America. Figure 2.1 illustrates the location of the 6 Western Canada plants, and those plants operating or under construction with the Fuchs™ aeration system (other facilities exist). Salmon Arm, Gibsons and Ladysmith were thefirstthree, full-scale ATAD facilities in BC and their successful operations provided the design specification for the facility in Whistler (Kelly et al., 1993). As an added measure of ATAD's success and suitability in winter climates, ATAD has again been selected in the upgrade and expansion of the Whistler facility. The facility is being expanded to accommodate a population equivalent to 52, 500 bed units (Kelly, 1996).  6  Lakefield, MN New Ulm, MN  FIGURE 2.1: Location of ATAD Facilities in North America (adapted from Kelly, 1996 & Smyth, 1996) 7  2.2 Volatile Fatty Acids  Fatty acids are defined as mono basic acids containing only carbon, hydrogen and oxygen, consisting of an alkyl radical, CH , C2FL,, etc, attached to a carboxyl group, -COOH (Sharp, 1990). The lower 3  weight species of fatty acids, loosely classified as short chain compounds, are referred to as volatile fatty acids (VFA). Table 2.1 list these species and their chemical structure. Terminology is used interchangeably, acetate and ethanoic acid also referring to acetic acid, propionate and propanoic acid to propionic acid. Similarly, VFA are also referred to as carboxylic acids.  TABLE 2.1: VOLATILE FATTY ACID SPECIES Structure  Compound acetic acid  CH3COOH  propionic acid  CH3CFLCOOH  iso-butyric acid  (CH ) CHCOOH  butyric acid  CH (CH ) COOH  valeric acid  CH (CH ) COOH  iso-valeric  (CH ) CHCH COOH  2-methylbutyric  CH CH CH CHCOOH  3  2  3  2  3  2  3  3  2  3  2  2  2  3  VFA are one of numerous biodegradable materials utilized by micro-organisms as substrate in wastewater treatment.  Most importantly for this research, acetate and propionate have been  identified as one of the most effective substrates in the enhanced biological removal of phosphorus (Rabinowitz, 1985). The model in Figure 2.2 illustrates the two phase process; bacteria are conditioned to take up greater amounts of phosphorus in an aerobic environment through initial stimulated release of phosphorus in a preceeding anaerobic zone.  8  acetate & propionate  anaerobic zone  f PHAs ) bto-P bacteria  V  /  available carbon substrates  aerobic zone  bk>P bacteria  FIGURE 2.2: Model of Enhanced Biological Phosphorus Removal (takenfromChu, 1995)  9  Natural levels of volatile fatty acids found in wastewaters are principally the result of fermentation, due to extended retention times in the sewage collection systems. At the same time, as detailed in reviews by Chu (1995) and Atherton (1995), it is the fermentative pathway that has been adapted in the dedicated production of VFA from primary sludge for biological phosphorus removal. Similarly,  Mcintosh & Oleszkiewicz (1996) highlight "VFA produced through fermentation  processes" as one of the prinicple sources of carbon substrate for denitrification treatment.  Fermentation can be promoted within a primary clarifier, or provided in a dedicated side-stream fermenter.  Atherton (1995) provides an excellent review of both of these options for VFA  production in comparison to her investigations with a main-stream fermenter. The use of either sidestream or main-stream fermenters is preferrable as it allows for the direct input of the VFA rich effluent to the desired zone in BNR processes .  2.3 Volatile Fatty Acids in Therophilic Aerobic Digestion  The concept that thermophilic aerobic digestion could also be used for the purpose of VFA production stemsfromboth positivefindingsand the theory that the oxygen restricted environment in the reactors allows fermentation metabolism to occur.  2.3.1 Detection  At the first full scale thermophilic aerobic digestion facility in the UK, acidic odours were the first indication that VFA were being produced (Morgan et al., 1984). Associated with low DO levels, subsequent sampling of TAD reactor contents confirmed the presence of VFA. In discussion of these and other results, it was concluded that VFA production/accumulation was ideal for anaerobic 10  digestion, which follow in dual digestion facilities (Casey, 1984). In specific assessment of a dual digestion process in Germany, Hamer & Zwiefelhofer (1985) also noted an increase in VFA concentrations from feed to the ATP reactor and additionally recorded complete elimination in the anaerobic digestion phase. A similar pattern was demonstrated by other dual digestion facilities in Europe. In an evaluation of a decade of opeating data from full scale facilities, VFA (acetate) concentrations increasedfrom2470 (1140) mg/L in raw sludge, to 6081 (3315) mg/L in the ATP reactor, down to 325 (320) mg/L after anaerobic digestion (Baier & Zwiefelhofer, 1991).  Since VFA in final effluent are considered an indication of incompletely stabilized material, this ultimate elimination is a positive result. For example, in the full scale facility in Palmersford, UK, although low aeration rates were found beneficial in improving temperature elevation in ATAD, it was discussed that air levels may need to be increased to reduce the production of VFA for a stabilized endproduct (Wolinski, 1985). It has subsequently been demonstrated that VFA can be eliminated infinalTAD effluent.  2.3.2 Theory of Production  Isolating cultures in bench scale studies, Mason & Hamer were one of thefirstgroups to propose a model for VFA production in thermophilic aerobic digestion (Mason et al., 1987a). Using yeast cells as substrate, initial results confirmed that VFA were only produced in an oxygen limited environment. Although the quantity of each species varied with retention time, acetate was the predominant species. At concentrations of 1400 mg/L to >2500 mg/L, acetate levels were 5 to 10 times greater than any other VFA (Mason et. al, 1987b). In further studies with oxygen limited conditions, VFA concentrations exceeded 6000 mg/L, again with acetate predominating (Hamer, 1987). Based on these results the model proposed that, in oxygen limited environment, acetate was produced 11  simultaneously with the enzymatic degradation of substrate bacteria, as a result of fermentative metabolism. At the same time, the model predicts the sequential disappearance of VFA, starting with acetate, as "preferred" substrates reach exhaustion. The model does not predict accumulation (Hamer, 1987). More recent investigations by the same group of researchers continues to support this theory, and demonstrates simultaneous production and utilization of acids (Haner et al., 1994)  Bomio et al., (1989) attempted to expand on this model with similar studies using "natural substrate", primary and secondary sludge collectedfroma wastewater treatment plant. Under neither high, nor low, aeration rates was a substantial quantity of VFA produced. In comparison to influent VFA concentrations, the maximum increase attained was only 20%. It is interesting to note that both studies acheived maximum levels around 36 hours, followed by utilization of acids to basically zero concentration.  At the Salmon Arm facility in BC, unconfirmed acetate levels of 10, 000 mg/L were reported and thus stimulated investigation into VFA production at full-scale. Kelly (1990) holds that both oxidation and fermentation are occuring through the presence of facultative microorganisms, but agrees it is fermentation which accounts for much of the formation of VFA.  More recently, Chu (1995) highlights that although fermentation does produce VFA, typically propionate also represents a significant proportion of VFA; the sole dominance of acetate in ATAD was not observed although it represented 70-80% of VFA species.. Chu offers a number of alternative mechanisms, in addition to fermentation, that could be responsible for acetate accumulation:  12  • aerobic oxidation of VFA • mutant atp behaviour • accumulation of NADH switches carbon flow towards acetic acid • inefficient coodination or uncoupling of the oxidative (TCA cycle and elctron transport chain) and non-oxidative (glycolysis) phases of glucose metabolism, resulting in acetyl-coA being diverted to acetate  From the results of his own investigations, Chu favours the later explanation referred to as the "overflow pheomenon", and a combination of all processes including fermentation. At the same time, 2,4-dinitrophenol was identified to inhibit acetate consumption, resulting in large accumulations of acetate in batch experiments, suggesting that other agents may exist that inhibit acetate consumption. Hamer (1987) also suggested inhibition of VFA degradation as an explanation for VFA accumulation, a contradiction to the predictions of his model.  More studies are required to accurately determine the bio-chemistry of VFA metabolism in thermophilic aerobic digestion, especially as the influent streams are so different and themselves variable. At the same time, not all operating parameters have been systematically investigated for their effect. The focus of this research is on assessment of VFA production in ATAD at the operations level.  2.3.3. Effects of Operating Conditions  Aerobic thermophilic digestion is used in both ATAD and ATP, dual digestion systems. All configurations are capable of attaining stabilization and pasteurization, if so designed.  The  simultaneous production of VFA has been established with adjustments to certain operating 13  parameters. The following sections highlight the research that identified these parameters and the investigations that have assessed their impact on VFA production. This review should illustrate how the project objectives were established, and how operating parameters were set.  2.3.3.1 Temperature  As a product of biological activity, VFA production is a function of temperature. This is demonstrated in the seasonal decrease in influent wastewater concentrations during the winter (Atherton, 1995). Specifically, UBC's pilot plant influent demonstrated an increase from 8 - 25 mg/L between November and February, to 18-35 mg/LfromApril to September. Similarly, increases in temperature alone have shown to increase VFA production in anaerobic digestion (Rimkus et al., 1982). With respect to the overflow phenomenon, studies suggest that the coordination of oxidation and non-oxidation phases is less at elevated temperatures (Chu, 1995).  In ATAD systems, heat is generated in the system by biological oxidation of substrate and the energy input for mixing and aeration. At full-scale facilities, studies have shown that the majority of the heat is biologically produced; studies by one researcher have quantified it at 70 - 80% (Ponti et al., 1995b). This same "auto-heating" is not demonstrated with smaller scales systems or with short retention times (Gould & Drnevich, 1978, Kelly, 1990) . At UBC's pilot plant, this inefficiency is compensated for through increased mechanical energy. As illustrated in Figure 2.3, increases in mixer speed of as little as 20 rpm resulted in changes in reactor temperature (Chu, 1995).  14  FIGURE 2.3: Temperature Effect of Changes in Turborator™ Speed (Chu, 1995)  15  Typical operating temperatures for thermophilic aerobic digestion systems are listed in Table 2.2. These temperatures should promote VFA production if other conditions are condusive.  TABLE 2.2: TYPICAL TAD OPERATING TEMPERATURES First Cell  Subsequent Cells  Reference  35 - 5 0 ° C  50-65°C  (U.S.EPA, 1990)  50-55°C  55 - 7 0 ° C  (Kelly, 1991)  60-68°C  anaerobic digestion  (Baier & Zwiefelhofer, 1991)  2.3.3.2 Aeration  Originally, the ATAD system was designed with specifications to maintain a measurable level of dissolved oxygen (Gould & Drenevich, 1978, Vismara, 1984); however, the aeration rates required to produce such an environment cause cooling of the system and result in excessive consumption of energy (Appleton et al., 1986b; Edgington et. al, 1993). In addition, it has been demonstrated that aeration rates, set to provide an oxygen restricted environment within ATAD reactors, increase solids removal rates and result in overall higher solids destruction (Mason et al., 1987b; Kelly, 1990). The theory is that the resulting mixed culture of aerobic and facultative anaerobic bacteria functions more efficiently than a "mono-culture", as found with strictly aerobic processes, and is additionally more stable (Hamer, 1987).  Aeration levels are now established to produce environments described as oxygen deprived (Boulanger, 1995), micro-aerobic (Chu, 1995), anaerobic aerated (Mcintosh & Oleszkiewicz, 1996). 16  As measurement of very low dissolved oxygen levels are often immeasurable, ORP has been found to be a more effective monitoring instrument ( Morgan & Gunson, 1987; Kelly et al, 1993). Values at the facilities investigated in BC, detected redox values between 30 mV and -350 mV in the first reactor, with less negative readings in the second reactor (Kelly, 1990). In recent pilot scale studies investigating oxygen transfer efficiency, negative redox was registered during all studies (Ponti et al., 1995b).  Along with the original design to provide an aerobic environment, Gould & Drenevich (1978) also asserted that pure oxygen was required for aeration in ATAD for oxygen transfer efficiency and positive heat balances.  Comparative studies in the UK were some of thefirstto demonstrate that  air could be efficiently employed and additionally, was superior to pure oxygen with respect to oxygen utilization efficiency (Wolinski, 1985; Morgan & Gunson, 1987). At the same time, Booth & Tramontini (1984) suggested that the higher oxygen utilization with air was a result of carbon dioxide stripping. In contrast, Fuggle & Spensley (1985) argue that air results in greater heat losses and is thus, less desirable. Both air and pure oxygen are used in full-scale ATAD facilities, and both systems have demonstrated the ability to produce VFA.  Using air, pilot scale studies by Chu (1995) assessed the effect of aeration on VFA production from primary sludge in ATAD. Initially running 2 reactors in series results indicated that the highest accumulation of VFA occurred under the lowest aeration level in thefirstreactor. Switching to 2 single stage systems in parallel, to provide a control reactor through experimentation, airflowrates of 0 to 165 ml/min were assessed. Net VFA production increased with a decrease in aeration with 950 mg/L being the maximum recorded concentration.  At this same time, the effect of "air" aeration was assessed on a mixed sludge feed by Boulanger 17  (1995; Boulanger et al., 1984 and 1995). With the reactors configured in a two stage process, aeration was varied through redox levels of -300 mV to +100 mV, corresponding generally to dissolved oxygen levels of <1 mg/L to >1 mg/L . VFA concentrations increasedfrom<10 mg/L to 724 mg/L in thefirststage, and 225 mg/L in the second stage with the decrease in aeration.  Similar aeration studies have been carried out using pure oxygen and primary sludge at the University of Manitoba (Mcintosh & Oleszkiewicz, 1996). Within an ORP range of-10 mV to -225 mV (0.14 V/V-hr), there was no net accumulation of VFA, whereas with ORP values consistently <300 mV (0.025 V/V-hr), net increases of approximately 1500 mg/L resulted in reactor concentrations around 3000 mg/L.  The aeration levels used in these studies are comparable to full scale facilities with respect to resulting ORP values. The low aeration rates in ATAD promote VFA production.  2.3.3.3 Retention Time  Since there is no recycle in TAD processes, retention time is synonymous with SRT and HRT. Based on feeding rates, a minimum retention time exists, before wash-out occurs, where energy generated by the bio-oxidation of substrate is not sufficient to provide autoheating (Jewell and Kabrick, 1980). This is illustrated in the requirement of many dual digestion system with retention times of less than 1 day to either pre-heat feed sludge, or heat the aerobic reactor itself (Bruce & Oliver, 1987). Similarly, above a maximum retention time, substrate is exhausted and again insufficient biologically generated heat is produced (Wolinski, 1985; Kelly et al., 1991). Typically, total ATAD retention time ranges between 6 and 10 days, with equal retention time in each stage (Burnett, 1995).  18  The relationship between retention time and VFA production was noticed early in studies. As described in section 2.3.2, in bench scale studies with isolated cultures, acids were shown to accumulate over thefirst36 hours, then gradually disappear. (Mason et al., 1987b; Bomio et al., 1989). Although the actual timeframeof these results may be incorrect, it illustrates that VFA can be degraded by thermophilic organisms with time.  In the studies mentioned above, Chu (1995) also investigated the effect of retention time on VFA production in ATAD. Initial results with reactors in series, indicated that the highest accumulation of VFA ocurred in thefirststage reactor. This result was also confirmed by Boulanger (1995). In subsequent parallel studies, VFA production was shown to increase with a decrease in retention time from 6 days to 3 days.  Similarly, Mcintosh & Oleszkiewicz (1996) also investigated the effect of varying retention time on V F A production using their pure oxygen system as described above. Although results indicate a decrease in net VFA production with a decrease in retention timefrom24 to 12 hours, in contrast to findings by Chu, percent increases and gross concentrations in the TAD reactors did not demonstrate similar trends. In comparison of absolute values, the shorter retention times in Mcintosh & Oleszkiewicz's studies produced 3 times the concentration of VF A. Similarly, comparison toVFA levels in ATP reators in dual digestion, shows higher concentrations have been realized with even shorter retention times: ATP retention times of 18 - 24 hours produced >6000 mg/L (Baier & Zwiefelhofer, 1991), while retention times of 3 days in TAD generate less than 600 mg/L. These general results support the relationship proposed by Chu (1995) that reduced retention time enhances VFA production.  At the same time, in a review by Ponti et al (1995a), studies have shown how retention times in TAD 19  reactors, established with frequent feedings of smaller volumes, improved degradative efficiencies due to smallerfluctuations,while volume changes of more than 20% of the working volume resulted in adverse effects. As an example of ineffective processing, the bi-weekly feeding schedule and 16 day retention time in one UK plant resulted in poor destruction, and difficulty in attaining designed process temperatures of 50°C (Edgington et al., 1993). Frequent volume changes have also demonstrated to reduced electrical requirements due to increased microbial efficiency (Ponti et al., 1995b). VFA production could potentially also be enhanced by increased feeding frequency.  2.3.3.4 Feed Sludge  As discussed in previous sections, a sufficient quantity of substrate is critical in ATAD to attain sufficient heat energy from aerobic bioxidation. Typically, 4 - 6 % total solids provides adequate volatile content (U.S. EPA, 1990; Deeney et al., 1991; Kelly et al., 1995).  The quality of sludge is also an important facture. Primary sludge is theorized to require longer treatment, as it is initially less stabilized than secondary sludge (Smith Jr., et al., 1975). In addition, both the irregular composition and concentration of the primary sludge can result influctuatingand unstable digestion (Ponti et al., 1995).  In contrast, secondary sludge is theorized to more suitable for ATAD as it is closer to the oxidative state of thermophilic culture (Mason et al., 1987). The other theory that proposes secondary sludge as a more effective substrate in ATAD is referred to as the "t.v. dinner theory": although primary sludge has a higher volatile content, secondary sludge, consisting of biomass, provides the required substrate pre-packaged in required ratios. In ATAD, this material is then made readily available to process biomass through lysis (Kelly et al., 1995). Both primary and secondry sludge, including 20  mixtures, have been successfully treated in thermophilic aerobic digestion systems.  With respect to enhancement of VFA, secondary sludge is chemically the most suitable. Under oxygen limited conditions, aerobic bio-oxidation of the substrate biomass results in the production of carbon dioxide, process biomass and soluble by-products. In addition, as nitrification is inhibited at the high temperatures found in TAD reactors, by-products formation is limited. The conversion of substrate biomass can thus be represented by the following equation, which clearly illustrates how VFA production should be enhanced with the addition of secondary sludge (Hamer & Zwiefelhofer, 1985).  CH O N . + a(0 ) L4  04  0 2  2  (CH O , ^ _ } + c (COJ + d (H 0) + e (NH*) +f(CJT L8  0 4  0  23  2  COOH)  2n+1  VFA  The main concern in digesting secondary sludge is the release of nutrients previously removed in wastewater treatment and the additional load on plant capacity when recycled to the process. Most critically, phosphorus is readily releasedfromsecondary sludge when mixed with primary sludge and under aerobic digestion due to lysis (Anderson & Mavinic, 1993; Rabinowitz & Barnard, 1995). Studies have confirmed that digestion of mixed sludge feed in ATAD results in subsequent nutrient release (Boulanger, 1995). At the same time, anaerobic digeston of mixed sludge also results in phosphorus release, requiring treatment before recycle (Knezevic, 1993; Niedbala,1995; Rabinowitz & Barnard, 1995).  Effluentfromthe ATAD process in Salmon Arm, BC where primary and secondary sludge are cothickened before digestion, has been recycled without additional treatment. Although operational difficulties suspended the full scale trial before impact could be assessed, subsequent bench scale studies predicted only minimal increases in phosphorus release and uptake, and additional full scale 21  studies were discontinued (Kelly, 1990). Further enhancement of the production of VFA in ATAD could potentially compensate for the release of nutrients.  2.3.3.5 Pre-Solubilization  Based on the theory that secondary sludge provides a pre-packaged substrate for micro-organisms in the digestion process, pre-solubilization of secondary sludge feed is intended to release this material for direct availability to process micro-organisms, eliminating a potentially rate-limiting step. Even in thermophilic digestion, where both high temperatures and increase enzyme production result in the lysis of cells and the expulsion of cell contents into solution (Hamer, 1987), lower initial reactor temperatures with cooler feed, lower osmotic pressure or more resilient bacteria could delay the release of this ideal substrate (Brock & Madigan, 1991). Chemical solubilization is a measured and controllable mechanism that can be optimized for a given feed stream.  The secondary sludge at UBC had previously been assessed for optimum chemical dose and mixing time for pre-solubilization, with both calcium hydroxide and sodium hydroxide (Knezevic, 1993). Based on the results of the application of the pre-solubilized sludge in anaerobic digestion, and the demonstrated enhancement of COD removal and methane gas production, it was hypothesized that VFA production could similarly be enhanced.  The application of thermophilic aerobic digestion in stabilization and pasteurization of municipal sludges has been widely demonstrated. Similarly, the benefits of ATP in dual digestion have also been well documented.  The enhancement of volatile fatty acids production in both processes, to  supplement nutrient removal and methane production respectively, has been proposed and partially evaluated. The goal of this thesis is to contribute additionalfindingsto this area of research. 22  3.0 METHODS AND MATERIALS  3.1 Experimental Set-Up  All experiments were conducted at the University of British Columbia's Pilot Plant, located on South Campus. The wastewater treatment facility with two parallel BNR trains, configured as a modified UCT process, treats sewagefromon-campus housing and residences. To achieve adequate solids loading to the process, sewage is pumped twice dailyfroma main sewage line into three equalizing tanks at the head of the plant. Raw sewage is buffered daily with the addition of approximately 500 g of sodium bicarbonate to each tank. All effluent and discharges are returned to the main sewage line for treatment at Annacis Island, Vancouver's wastewater treatment facility. A process flow diagram of the wastewater treatment plant is provided in Figure 3.1. Actual photos of the facility are provided in Appendix B.  The pilot scale ATAD system, consisting of 2 sealed and insulated reactors, built for previous research, was brought back on line with the plant's wastewater treatment process in June, 1995. Experiments were run between September and December of the same year, with samples being concurrently analyzed in UBC's Environmental Engineering Laboratory. Four experimental runs were designed to test the influence of secondary sludge on ATAD sludge digestion, and 2 supplemental runs investigated the influence of pre-solubilization of the secondary sludge. For all experiments, the 2 ATAD reactors were configured in parallel, to maintain a control throughout the test period: 100% primary sludge for Runs 1 to 4, and identical sludge mix ratio, unsolubilized for Runs 5 and 6. The sludge mix ratios were selected to cover the rangefrom100% primary to 100% secondary, as well as to facilitate camparison to previous research completed at UBC (Knezevic, 1993; Boulanger, 1995; Niedbala, 1995). Table 3.1 outlines the experimental design. 23  2 C  -o  M  O  o  u CO  O  CO  c  co E  CD  d) c  o  CD  ig-a ^  CO CO  c fc o o ' C ' C (]} CD Q . Q . C 0 CO  CO -Q CO .Q l - T - CM CM  FIGURE 3.1: Process Flow Diagram of the UBC Pilot Plant  24  CO O )  eg <u co ~  CD  c "co  T3  TABLE 3.1: EXPERIMENTAL DESIGN Run  Primary/Secondary Sludge Ratio (based on TS) Test Reactor Control Reactor  1  100/0  100/0  100/0  65/35  2 SRT 2 SRT  acclimitize to 35/65 35/65  3  2 SRT 2SRT  acclimitize to 65/35 2  Timing (minimum)  100/0  2 SRT 2 SRT  acclimitize to 0/100 0/100  100/0  2 SRT  acclimitize to pre-solubilization  acclimitize to 0/100  2 SRT  0/100 pre-solubilized  0/100  2 SRT  acclimitize to 35/65 & pre- solubilization  acclimitize to 35/65  2 SRT  35/65 pre-solubilized  35/65  2 SRT  4  5  6  3.1.1 Sludge Source  Primary sludge was generatedfroma side stream clarifier, as the clarifier serving the process train is an intermittent mix, upflow clarifier. To maintain consistent total solids (TS) the flow rate to the clarifier was initially estabished at 6.25 L/min, and gradually reduced with the decreased use of primary sludge to 5.4 L/min. Sludge was pumpedfromthe bottom of the clarifier every 5 minutes for 30 seconds, to a second clarifier for further thickening and storage. Sludge was transfered to the feed tanks daily, with additional wasting to the drain, to maintain a consistent sludge age.  25  Secondary sludge was wastedfromthe last aerobic zone of the UCT process. Every 24 hours, 100L of sludge was transferred to a pre-thickener. The sludge was allowed to settle andfreewater was manually sucked off with the use of pump; the remaining material was pumped to the secondary thickener. Generally, the sludge condensed to 1/5 its original volume within the hour before transfer the thickener. To avoid anaerobic conditions during holding, the contents of the secondary thickener were periodically stirred up, and left to settle a minimum of an hour before transfer to the feed tanks.  Primary and secondary sludge was metered into the feed tanks once daily by gravity flow. Mix ratios were based on TS calculated every 24 hours, with dilution with distilled water to maintain a 1% sludge feed. Although this would be considered "thin feed" in ATAD, it is the maximum thickness of secondary sluge that can be readily produced from the process, at this scale, for the daily quanitities required.  Both feed tanks were continuously stirred to keep solids suspended for  homogenous consistency at the outlet at the bottom of the tank. A process flow schematic of the ATAD experimental set-up is provided in Figure 3.2, and photos in Appendix B show the actual equipment.  Pre-solubilization of feed sludge was carried out in the feed tanks with the addition of a measured quantity of sodium hydroxide (NaOH). Based on the results of previous research at UBC, 15 meq/L of secondary sludge was used (Knezevic, 1993). However, due to the semi-continuous operation of the ATAD reactors, the "optimum" 5 hours of mixing for the pre-solubilization of secondary sludge could not be provided. Instead, NaOH was dissolved in distilled water and added to the test feed tank immediately after a feeding to provide a minimum of 1 hour pre-solubilization. Consequently, only 4 litres of sludge did not receive the prescribed 5 hours of mixing.  26  TEST SIDE  CONTROL SIDE -> to waste bucket  sample 7  sample 8 24 U/day  24 LJ/day  ATAD Reactors  thickener  thickener  feed tanks  > sample 4  1 L/hr t primary sludge sample  < sample 5 X  X >  ^  >  L  1 L/hr J sample 6| secondary sludge sample  FIGURE 3.2: Process Flow Diagram of Experimental ATAD Set-up  27  3.1.2 ATAD Reactors  Two, 125 L stainless stell tanks, fitted within insultated tanks, served as the ATAD reactors. The tanks were sealed with a lid perforated for: the sludge inlet/outlet pipe, air exhaust port, temperature and ORP probes. The shaft of the mixing and aeration device also perforated the lid. All perforations were well-sealed to maintain high insulation proporties as well as to prevent escape of off-gases, or entry of outside air. Figures B5 (a) and (b), in Appendix B, illustrate the reactor lid detail.  The ATAD reactors were operated in semi-continuous mode through automatic feeding and manually wasting. Both feed pumps were Moyno progressive cavity pumps (model 33101). Each pump was equipped with a speed controller to deliver 1L of sludge during a 30 second "on" period established by an electrical relay. The pump used to remove sludgefromthe reactors was a Masterflex peristaltic pump (model 7585-50), top mounted to suck sludge out throgh the same down pipe used for feeding. Manually operated, each reactor was wasted separately into a bucket to control the volume of digested sludge removed and to obtain ATAD sludge samples.  3.1.3 Retention Time  A retention time of 3 days was selected for experiments based on the results of previous work on VFA production in these same reactors ( Boulanger, 1995; Chu, 1995). Based on a semi-continuous feed rate of 1 L/hr, an average volume of 72 L was required. During regular operations, 24 litres of sludge was wasted once a day and the sludge volume rose dailyfrom60 L to 84 L. During test runs, wasting occured twice a day in order to obtain samples. Therefore, to maintain an average volume of 72 L with only 12 L being removed at a time, oscillations were established between 66 L 28  and 78 L.  For 10 days prior to acclimitization for Run 5, when it was required to build up the sufficient quantity of secondary sludge for the last two runs, the retention time in the reactors was extended beyond 3 days. Both reactors werefilledwith 30 L of partially digested secondary sludge and 30 L of fresh secondary sludge. Every second day, the contents of both reactors were interchanged and mixed, to ensure consistency between reactors.  3.1.4 Mixing and Aeration  Mixing and aeration was supplied by an aspirating device, supplied and modified by Turborator Technology™ for the pilot plant system. Air is introduced through the hollow shaft of the device, and thoroughly mixed with contents of the reactor through a patented blade assembly. Turborator™ techonology is used in the ATAD facility in Salmon Arm, BC (Kelly et al., 1993).  The supply of compressed air to the device was controlled using both a regulator and air measuring devises. Airflowwas metered at levels within the lower end of the 0-165 ml/min range shown to enhance VFA production in the ATAD reactors (Chu, 1995). During thefirst4 runs, air was supplied equally to both reactors by splitting the flow after the meter. During Runs 5 & 6, two additional flow meters were installed on each of the split lines to more accurately measure flow to each reactor. To compensate for variability between the airflowdevices, the meters were switched between the two reactors every 3 days. The set-up of air flow measuring devices in depicted in Figure 3.3.  29  FM032-15  J  r w  TT  Test Turborator  Control Turborator  (a) Runs 1 to 4  FM032-15  Control Turborator  Test Turborator  (b) Runs 5 & 6 FIGURE 3.3: Air Flow Meter Set-up  30  Exhaust gases were ventedfromthe reactor. Initially, a 25 mm inside diameter hose had simply been connected to the outlet port on the reactor lid to vent off-gases out of the trailer. This system, which theoretically allowed outside air to enter the reactor headspace and thus supply additionally oxygen, was replace by 4 mm tygon tubing discharging through a water trap to the atmosphere.  3.2 Monitoring Variables  The following variables were monitored on-line or at regular intervals throughout the research period, as indicators of process performance and stability. Operating conditions were established to match EPA design requirements as closely as possible, as well as to correlate with previous research with the same system to facilitate comparison of results.  3.2.1 Temperature  The temperature of the reactor was maintained between 45 °C and 55 °C, typical for first stage reactors (Kelly, 1990; U.S. EPA, 1990). Heating of the reactors was provided by mixing, aeration and biological activity. Temperature was monitored on-line with a temperature probes connected to a data logger (Labtech Notebook/XE). Readings taken every 10 seconds were averaged every 5 minutes and plotted  continuously on a dedicated monitor. Readings were verified with a  thermometer on a bi-monthly basis.  3.2.2 Turborator™ Speed  Due to the surface area to volume ratio of pilot scale reactors, the heat balance is not the same as for full scale facilities; the mixing and aeration equipment provides a larger portion of the heat input as 31  described in Section 2.3.3.1. For this reason, Turborator™ speeds were set to obtain the desired reactor temperature for the feed rate provided. As each Turborator™ has its own inherent efficiency (Boulanger, 1995), the mixers were controlled separately, although maintained within the same range.  Each Turborator™ was equipped with a high speed motor and speed controller. Maintenance required the Turborators™ to be stopped each day for cleaning. As the controllers were reset each time, speeds were measured and recorded every 12 hours to 24 hours with a tachometer.  3.2.3 ORP  Oxidation reduction potential (ORP) was not controlled, but monitored as an indicator of oxygen levels. ORP values of 0 to -300mV were considered positive indicators of an ATAD environment (Kelly et al., 1993), and consistency of a value during a run an indicator of stability and steady-state reactions. As with temperature, ORP was monitored on-line. Measurements were taken every 10 seconds and an average value was calculated, logged and plotted every 5 minutes.  Due to the high temperatures in the reactors, two probes were used in each reactor to ensure a higher degree of accuracy. Increases in the difference between the two probes also indicated the need for cleaning. ORP calibration tests were performed at the beginning of the experimental period, using AgCl. Consequently, each reactor received one new probe.  3.2.4 Dissolved Oxygen  Dissolved oxygen levels were measured in the ATAD effluent immediately after wasting to provide a second parameter for assessment of the reactor environment, and again to facilitate comparison to 32  previous research results. A YSI Model 54, DO Meter with model 5739 probe was immersed in the sample and allowed to stabilize for approximately 1 minute. The probe and meter were calibrated for each group of measurements.  3.2.5 Airflow  As detailed in Section 3.1.4, aeration was controlled with air flow measuring devices. For Runs 1 through 4 a single meter was used, Cole-Palmer FM032-15. For Runs 5 & 6 two meters were added, Cole-Palmer FM022-13. Due to the variability and sensitivity of the apparatus,flowswere recorded every 12 hours to 24 hours and adjusted after shaft cleaning, as necessary.  Prior to Run 5, it was attempted to check the accuracy of the airflowmeters, due to the discrepency in calibration information provided by Cole-Palmer. As illustrated in Figure 3.4, calibration rates for the same models varied by as much as 60 mL/min for different years. However, the low precision of the calibration tests did not allow for any better assessment and it was decided to use the more recent curves supplied by Cole-Palmer for evaluation of airflow rates. Since the airflow was split after the meter for Runs 1-4, even though the absoluteflowrates can not be assured, the relative difference should be zero. On the other hand, flow ratesfromRuns 5 & 6 can not be accurately compared to previous runs; however, ORP was used to confirm aeration rates were similar.  33  Model 032-15 160  0 -] 10  1  1  1  20  i 1 1 30 40 50 Meter Reading 1  1  1  1  1  60  1 70  Model 022-13 300  0  -I  1.0  1  1  20  1  1  1  i  1  1  30 40 50 Meter Reading  1  1  60  1  1  70  FIGURE 3.4: Air Flow Calibration Curves (adaptedfromCole-Palmer, 1995)  34  3.2.6 Air Composition  Reactor headspace air composition was measure in Runs 4, 5 and 6, to assess whether anaerobic reactions were prevailing, as ORP levels potentially indicated as such. Using aflowthrough gas sampling vial,fittedwith an adaptor for the exhaust gas outlet, a syringe was used to purge and fill the sample chamber. The tube was then sealed and removedfromthe port, and the exhaust venting system reconnected. The sampling vial is shown in Figure B5, photo (c).  The air samples were taken to the Environmental Engineering Laboratory for analysis within 2 hours of removal. A Fisher-Hamilton Gas Partitioner (model 29) with Spectra Physics Computing Integrator (model SP4290) was used to determine the % composition of oxygen, carbon dioxide, methane and nitrogen. An ambient air sample was taken in the trailer or in the laboratory for comparison.  3.2.7 pH  The pH of the feed and reactor contents was measured during test runs on samples removed from each feed tank and reactor. The pH meter utilized was a Fisher Scientific Accument pH Meter (model 25), calibrated daily with standard pH solutions of 4, 7 and 10, and a temperature probe. A magnetic stir bar was used to mix the sample during measurement.  3.2.8 Total Solids  Using between 60 and 75 mL of sample, total solids were determined daily by evaporating the measured volume of sample in a Fisher Isotemp (model 350) forced draft oven at 104°C. Analysis 35  was performed as outlined in Standard Methods (A.P.H. A. et al., 1989). Since a consistent feed of 1 % TS was designed as an experimental control, drying times were restricted to around 23 hours to allow use of results for the preparation of sludge feed.  To assess solids destruction efficiencies of ATAD, both the feed and ATAD effluent streams were additionally sampled every 12 hours during experimental runs. Based on the semi-continuous operation and 3 day retention time of the reactors, TS destruction data was calculated by applying a 3 day moving average. Using the daily average TS measurements, destruction rates were calculated from the difference between ATAD output, and the average of the previous 3 days input. The level of stabilization acheived by the ATAD system was assessed based on destruction rates during experimental runs only. In between the 6 Runs, process feed was altered and reactors were acclimitizing; therefore, neither efficient operation, nor treatment, were expected. Examples of the calculations for total solids, feed metering and solids destruction are presented in Appendix J.  3.3 Experimental Variables  A 500 ml sample was removedfromeach of the sample streams for the following constituent analysis.  3.3.1 Volatile Fatty Acids  Samples for volatile fatty acids (VFA) analysis were prepared on-site. Sludge was centrifuged at high speed,  approximately 12 000 rpm, for 10 minutes to separate solids that would interfer with the  analytical instruments. The supernatant was then sampled with a dedicated dropper and transferred to 2 ml clear glass GC vials (HP model 5181-3375 ) containing the preservative, 2% phospheric acid. Vials were crimped capped (HP model 5181-1210) andfrozenfor the duration of each test period. 36  Each sample was prepared in triplicate.  VFA analysis was performed in the Environmental Engineering Laboratory. The vials were allowed to defrost at room temperature 24 hours before analysis. A Gas Chromatograph (HP model 5880a) with Automated Sampler (HP model 7672A) was used for sample injection and analysis. The column used and instrument settings are as specified in GC Bulletin 751G, Supelco Bulletin 75 IE:  oven temperature  120°C  injection port temperature  180 ° C  detector temperature  200 ° C  detector type  FID  carrier gas  helium  gas  flow  20 mL/min  column length  4ft, 2 mm ID  column material  glass  column packing  60/80CarbopackC/0.3%Carbowax®20M/0.1%H3P0  4  Samples were analysed for acetic acid, propionic acid, iso-butyric acid and butyric acid, the 4 lower weight species of VFA. Previous research has indicated that these species predominate and additionally, acetate is the species of most interest for supplement to both Bio-P and anaerobic digestion (Atherton, 1995; Chu, 1995). Distilled water was analysed to test for contamination during preparation, and lab blanks were run to check instrument contamination.  During analysis of results, it was noted that samples that had been rerun the following day to double check anomalies, consistently registered lower concentrations of VFA. Two explanations are provided for this difference: either degradation of acids occurred once defrosted or volatilization of acids resulted with an increase in headspace in the vials, after some of the sample was removed for analysis. In addition, heat generated by normal GC operations would have heated the samples during 37  analysis, enhancing both degradation and volatilization. Subsequently, no rerun data was used although trends were confirmed. Studies by Bomio et al. (1989) detail the fate of VFA in samples during preparation and storage, and reported lower VFA concentrations even at temperatures as low as -2°C. The period between sampling and analysis was kept consistent for all runs.  Analysis of samples also resulted in obvious carry over between samples, specifically when analyzed sequentially by date rather than by sample stream. Higher weight VFA have longer detention times in the GC apparatus than was provided in the analysis of only the 4 lower weight species. As a result, peaks of valeric and methyl butyric acidfromthe previous samples were detected and registered in the first sample of a triplicate that otherwise registered little or no presence of VFA. Analysis of samples was subsequently performed in order of increasing VFA concentrations. This problem could be further alleviated with blanks set between different sample sets and analysis of all VFA species.  3.3.2 Nitrogen and Phosphorus  Samples for ortho-phosphate (P0 ), nitrates (NOJ, and ammonia (NH ) were also prepared on-site. 4  4  Sludge was centrifuged, as described for VFA samples, and using Whatman No. 4 fitlered into plastic sample tubes. Samples requiring dilution for the analysis within the instrument's range, 0.05 to 20 mg/L, were diluted 1 in 10 using distilled water. Ortho-phosphate and nitrate samples were preserved with a drop of 2% methyl mecuric acetate, later diluted to 1% as column degradation was evident. Ammonia samples were acidified to pH <3 using sulphuric acid, H S0 . Again, all samples were 2  4  frozen for the duration of the test period and defrosted only for analysis in the Environmental Engineering Laboratory. For nutrients in particular, samples were defrosted under refrigeration to avoid rapid warming and potential volatilization of sample constituents.  38  Total phosphorus (TP) and Total Keidjal Nitrogen (TKN) samples required digestion before analysis and samples werefrozento be prepared in the lab. For soluble TP and TKN, sludge samples were additionally centrifuged,filteredand acidified to pH<2 using sulphuric acid beforefreezing,as described above. Upon defrosting, before an aliquot of sample was transferred to a digestion tube, soluble samples were tip mixed while the unaltered sludge samples were each blended for 1 minute using a Braun Hand Mixer® to ensure a representative sample was removed. Along with the samples, a blank, known test solutions and standards were prepared according to Standard Methods (A.P.H.A. et al., 1989). Boiling chips and 10 mL of digestion solution were added to all tubes in final preparation for digestion. Samples were digested for 7 hours, allowed to cool and then diluted to 75mL with distilled water for analysis.  Analysis of samples was performed in the Environmental Engineering Labortatory using a Quick Chem A E System Unit, Automated Ion Analyzer by Lachat Instruments, with XYZ Sampler. Calibration checks were performed every 20 samples, with >10% deviation being unacceptable for continuation without recalibration.  3.3.3 Total Organic Carbon  Total organic carbon (TOC) is an indicator of solubilization; as such it was assessed most specifically in Runs 5 & 6. Runs 1 to 4 were also sampled, but only on every other day.TOC samples were centrifuged andfiltered,as described above, in preparation for analysis. For Runs 1 through 4, preparations were carried out in the lab on defrosted, blended samples.  For Runs 5 & 6, samples  were prepared andfrozenon-site, then defrosted and tip mixed in the lab prior to analysis.  A  Shimdzu Total Organic Carbon Analyzer (TOC-500) with ASI-502 Automatic Sample Injector was used for analysis. 39  3.4 Sampling Points  The samples for the experimental parameters and total solids were takenfrom6 sampling points in the process:  3 -  mixed liquor (unsettled secondary sludge)  4 -  Control feed  5 -  Test feed  6 -  secondary sludge  7 -  Control ATAD effluent  8 -  Test ATAD effluent  Mixed liquor was sampled directlyfromthe process during wasting, sample 3 A from A-side and sample 3BfromB-side. Feed sludge samples were removedfromthe feed tanksfroma valve located on the tank wall approximately 2 cmfromthe bottom. Feed tank contents were continually stirred and the valve wasflushedwith material before a sample was taken. During Runs 1 through 4, control feed samples also represented primary sludge; only during Run 6 was a separate sample taken from the transfer line to the feed tanks. Similarly, secondary sludge samples were represented by the test feed in Run 6, and control feed in Run 5 and were otherwise removedfromthe transfer line to the feed tanks. ATAD samples were takenfromthe volume pumped into the wasting bucket. Mixing of the ATAD reactor contents continued during wasting; however, mixer speeds were reduce to 250 rpm.  Sampling points are indicated by numbers in the process flow diagrams pesented earlier in  Figures 3.1 and 3.2.  The 4 principle streams that were sampled every 12 hours during experimental runs are in bold face. Comparison between corresponding feed and ATAD samples will illustrate the effect of TAD 40  treatment on a given feed stream, while comparisons between test and control samples should demonstrate the effects of secondary sludge addition and pre-solubilization of feed. Samples of the mixed liquor will provide an indication of wastewater treatment variability and, in comparison to the resulting "secondary sludge", effects of dewatering, thickening and storage should be evident.  3.5 Interpretation of Results  Since a control reactor was maintained through all runs, the inherent variability of sewage sludge can be eliminated; the effect of the test variable can be evaluated from the difference between the test and control reactors (T - C). Relationships and trends are then based on the difference between the (TC) values for each run. Differences between the control and test reactor in Run 1, when feed streams are both 100% primary sludge, should be minimal, although the reactors have demonstrated inherent differences in previous research ( Boulanger, 1995; Chu, 1995).  Comparisons are made based on the average, minimum, maximum, median, and standard deviation values calculated for each set of data. For VFA samples, triplicate data was averagedfirstbefore statistical analysis, and total VFA values are simply the sum of these average values for each of the 4 species measured. The paired t-test for sample means was used to establish if differences were statistically significant. Formulas for the calculations performed by Quattro Pro 4.0 for Windows are given in Appendix J.  Analytical results below instrument detection limits are labelled or highlighted in appendix tables, and detection limits are given. Negative values and "not detected" values are taken as zero. For statistical calculations and comparisons, if a number is given in the data tables it has been used in calculations, blank cells were ignored. This potentially results in values that are biased low. 41  4.0 RESULTS AND DISCUSSION  4.1 Experimental Set-up  Experimental runs were scheduled to be 6 days, with a minimum of 6 days acclimatization also, to provide 2 full retentiontimecycles in each case. Due to equipment repair and maintenance, to reduce the potential for process upsets during experimental runs, the acclimatization period was usually longer. The following table outlines the actual timing of the 6 runs.  TABLE 4.1: EXPERIMENTAL TIMETABLE Run  Dates  Test  Control  1  September 11 - September 16  100/0  100/0  2  September 27 - October 2  65/35  100/0  3  October 12 - October 17  35/65  100/0  4  October 27 - November 1  0/100  100/0  5  November 20 - November 26  0/100 pre-solubilized  0/100  6  December 2 - December 7  35/65 pre-solubilized  35/65  Some of the delays encountered, included clogging and failure of the control feed pump (due to the consistency of primary sludge) and power failures, which shut down all processes and computers at the pilot plant. As the plant was visited at least once every 12 to 24 hours, repairs were done immediately resulting in minimal upset to the ATAD process. Similarly, as all equipment self-started with the return of power, the processes were able to recover immediately. At the same time, the data logger also self-started so the time and duration of these events, their effect on ATAD and recovery 42  of the process were all recorded. The longest power outage was 8 hours long, occurring on the last day of Run 5, and resulted in run 5 being extended a extra half day. Other than this event, no major process upsets occurred during the 6 experimental runs.  4.2 Operating Conditions  The following parameters were measured to control and monitor the consistency of the feed stream and the ATAD process. Variations between test runs was expected due to the variation in feed characteristics with the introduction of secondary sludge and pre-solubilization. Variations between control runs, 1 to 4, was hoped to be minimal but inherent variability in sewage composition can not be eliminated. Similarly, variations between the reactors in Run 1, when feed streams were both 100% primary sludge, should also be minimal.  Tables summarizing the results are provided in Appendix C. For each of the 6 runs, data is provided as measured every 12 hours during the 6 days of testing. The average, range and standard deviation is calculated for each set of data for each run. Values will be highlighted in the following subsections.  4.2.1 Source Sludge  To provide an indication of the quality of sludge that was used for the experiments, settled primary and secondary sludge were sampled during all experimental runs as the feed tanks were being fed. In addition, unsettled mixed liquor (secondary sludge prior to decanting and thickening) was also sampledfromthe process at the time of wasting. As two separate process trains supplied mixed liquor for digestion, each was sampled separately before combined in thickener. Table 4.2 provides the 43  overall mean, and range of the various parameters analyzed, The variability of sewage sludge is evident.  TABLE 4.2: CHARACTERISTICS OF SOURCE SLUDGE Parameter  Primalry Sludge  Mix ed Liquor  Secondairy Sludge  avg  range  avg  range  avg  range  TP (mg-P/L)  40  22-57  129 A 93 B  93 - 175 A 49- 131 B  299  235 - 484  P04 (mg-P/L)  4.6  3.0-8.2  0.06 A 0.05 B  0.01 -0.15 A 0.03 - 0.08 B  111  55 - 136  NH4 (mg-N/L)  24  16-34  0.08 A 7.40 B  0.01 - 0.27 A 0.04 - 13.05 B  26.5  7.3 37.1  TS (g/L)  11.5  1.3 - 18.9  4.2 A 3.5 B  0.8-5.8 A 1.9-5.0B  11.6  1.3 18.9  Total VFA (mg/L)  198  62 - 291  4A IB  0- 12 A 0-3B  48.3  1 - 97  Note: A and B denote the two separate process trains supplying mixed liquor  This summary, with its large range of concentrations, presents an unstable picture of operations. On the other hand, as illustrated in Figures 4.1 to 4.4, this variability is largely between runs; consistency during each run was generally high (see Appendices C, E & G). Variability was introduced, however, when mixed liquor was introducedfromside B of the wastewater treatment process. Specifically, ammonia levels were noticeably different between A and B mixed liquor samples when B-side was initially brought on-line. Fortunately, no significant impact was recorded in resulting secondary  44  sludge. Ortho-phosphate shows the same trend, but as values were at or below detection limit, no conclusions can be drawn.  On the other hand, the decrease in ortho-phosphate and ammonia  concentrations in the secondary sludge in Run 5 was the result of the reduced retention time in the thickener, a consequence of the increased demand for secondary sludge as the mix ratio increased. Although secondary sludge was wasted from the thickener in addition to the volume used for feeding to try to stabilize sludge age, Run 5 was the peak of demand and the effects of this were evident: mixed liquor was visibly thinner, indicating process capacity was being exceeded.  Similarly, the reduced retention time also reduced VFA concentrations, droppingfrom>90 mg/L to <10 mg/L between Runs 3 and 4. Conversely, the decrease in VFA in primary sludge is mostly likely a reflection of decreasing seasonal temperatures and consequently reduced activity in the sewage collection system. This trend has been noted at the pilot plant during other research and generally in northern climates (Atherton, 1995).  The graphs also illustrate the effect of decanting and thickening of the mixed liquor. As phosphorus is initially tied up in the biomass of the mixed liquor, decanting of supernatant concentrates the residual, resulting in total phosphorus concentrations in the secondary sludge which are more than the sum of the contributionsfromthe mixed liquorfromA and B side. Retention in the thickener additionally results in the release of some of this stored phosphorus, indicated by the high levels of ortho-phosphate in secondary sludge. The apparent decreased release in Run 5 corresponds to a reduction in retention time in the thickener at peak demand. Similarly, the subsequent increased release in Run 6 is a consequence of an increase in retention time due to a decrease in demand.  45  1  2  3  Run  4  5  6  FIGURE 4.1: Source Sludge TP  46  40  1  2  3  Run  4  5  6  FIGURE 4.3: Source Sludge N H  4  300  1  2  3  Run  4  5  6  FIGURE 4,4: Source Sludge VFA  47  4.2.2 Temperature  The temperature of the ATAD reactors was maintained between 40 °C and 52 °C during all runs. Figures 4.5 to 4.10 illustrate the recorded on-line temperature of each reactor. The control reactor was always warmer than the test reactor, even during Run 1 when the feed was 100% primary sludge for both. Although this difference was found to be statistically significant, no correction factors have been applied in subsequent runs as neither mixer speed or aeration rates were consistent between runs and both parameters influence ATAD temperatures. In addition, the resulting VFA concentrations were higher in the test reactor, opposite to the predicted influence of temperature on VFA production and accumulation. Correction of the data would result in even greater differences between the test and control reactor with respect to VFA production.  All runs demonstrated an oscillating pattern through 24 hours, paralleling the rise in temperature during the day, and a decrease at night, indicating less than perfect insulation of the tanks. This same pattern was observed by Chu (1995). This pattern is less evident in later runs (Runs 5 & 6) as trailer heating was turned on for the winter. The sudden drop in the temperature profile in Run 5 is the result of a 8 hour power failure and a collapsed hole in the data.  From the continuously logged data the average temperaturefrommidnight to noon, and noon to midnight was calculated and listed in the tables in Appendix C, although the statistical calculations were performed on the entire data set. Table 4.3 summarizes these values for each run for the ATAD reactors.  48  52  £ 42 40 September 11th to 16th FIGURE 4.5: ATAD Temperature Profile, Run 1  £42  -  40 September 27th to October 7th  FIGURE 4.6: ATAD Temperature Profile, Run 2  52 O 50 a>  48  rpm increase from 925 to 935  Control ATAD  40 October 12th to 17th  FIGURE 4.7: ATAD Temperature Profile, Run 3  52 O 50 a) 48  trailer heat turned on  Control ATAD  Test ATAD  October 27th to November 1st  FIGURE 4.8: ATAD Temperature Profile, Run 4  50  8 hr power failure, collapsed hole in data  November 20th to 26th FIGURE 4.9: ATAD Temperature Profile, Run 5  52 drop in control mixer speed  O 50 C D 48 i _  3  -t—<  C O i _  Control ATAD  46  CD  Q. 44  E 42 CD  Test ATAD  40 December 2nd to 7th  FIGURE 4.10: ATAD Temperature Profile, Run 6  51  TABLE 4.3: AVERAGE ATAD TEMPERATURE Run  Date  Control  Test  1  09/11 -09/16  49. r c  46.6°C  2  09/27 - 10/02  48.8°C  44.5°C  3  10/12 - 10/17  45.0°C  43.9°C  4  10/27-11/01  44.2 °C  42.1°C  5  11/20-11/26  44. r c  43.1°C  6  12/02 - 12/07  44. r c  42.8°C  Although the temperature did decrease from Run 1 through 4, paralleling the increased addition of secondary sludge, the decrease can not be attributed solely to this variable. Other pilot scale studies have shown that lower temperatures are attained with secondary sludge versus a mixture of primary and secondary (Trim & McGlashan, 1984); however, it is the difference between the test and control reactor which must be assessed, and it is inconsistent.. As discussed above, poor insulation resulted in temperature fluctuations, and the decrease in temperature from September to November can equally be attributed to overall temperature decreases associated with autumn. This is confirmed by the parallelled decrease in the control reactor's temperature, and the subsequent temperature increase in both reactors after October 29 when trailer heat was turned on. th  Although only recorded in Runs 5 & 6, the temperature of the feed sludge was measured during pH measurements. During these runs, temperatures ranged between 13°C and 16°C. However, presolubilization resulted in immediate temperature increases in the test feed streams of as much as 0.7 °C (test feed - control feed). Feed sludge temperatures remained elevated during feeding, and were further increased 12 hours after addition of NaOH in most cases. Temperature changes were  52  more pronounced in Run 5 with 100% secondary sludge feed; the maximum recorded difference between control and test feed was 1.2°C. During both runs, the trailer was being heated, although not to room temperature.  The contribution of the mixing and aeration unit to heat generation is obviousfromthe temperature drop in Run 5, when an electrical outage occurred. Although it can be argued that because no air was being supplied to the reactor during this same period, that aerobic oxidation of substrate was also inhibited (and thus biological contribution to heat energy was also eliminated), in this case, the scale of the system favors mechanical energy as the predominant contributor of heat energy as presented in the literature review and illustrated in the next section.  4.2.3 Turborator™ Speed  Turborator™ speeds were maintained fairly consistent between reactors throughout the entire research period. Both the control and test reactor recorded a median of 934 rpm. Speed setting were established at 925 rpm, and increased to 935 rpm on October 14*. The average daily speed, calculated from 2 to 3 readings taken over each 24 hour period, is plotted in Figure 4.11. The variability of the apparatus is evident.  The two lowest readings were the result of increased resistance on the Turborator™ shaft. Constant vibration of theframe,upon which the Turborators™ are mounted, results in slight movement of the ATAD reactors and misalignment of the Turborator™ shaft with the opening in the reactor lid. The reading of >950 rpm were the result of resetting speed controllers too high after having being stopped for daily cleaning. Turborator™ speeds were allowed a minimum of half an hour to stabilize before a reading was recorded; this was obviously not always sufficient. 53  In support of the discussion of the predominance of mechanical energy at pilot scale to reactor temperature, the increase in Turborator™ speeds on October 14 is clearly registered as a th  temperature increase in Run 3 (see Figure 4.7). Similarly, one of the two periods of low speed occurred on December 5 in the control reactor and is registered as a temperature decrease th  unmatched by the test reactor in Run 6 (see Figure 4.10). The temperature decrease on December 4 in Run 6, paralleled more closely by the test reactor appears to have been caused by another th  variable. As Turborator™ speeds were averaged for a 24 hour period, not allfluctuationsare recorded.  970  C avg = 929 rpm T avg = 934 rpm  950 |930 910 890  09/03  increase in speed setting  (min 701 rpm) 09/17  10/01  10/15  10/29  11/12  Date (mm/dd) — Control Reactor—Test Reactor  FIGURE 4.11: Turborator™ Speed  54  11/26  4.2.4 ORP  The redox potential of the ATAD reactors was also monitored on-line. The readingsfromthe two probes per reactor were averaged and plotted for each of the 6 runs in Figures 4.12 to 4.17. Except for Run 5, where the ORP was very unstable in the test reactor, ORP was consistent during experimental runs. Values range between -200 mV and -500 mV, with the test reactor always being more negative. Based on traditional definitions this would indicate an anaerobic environment within the ATAD reactors; however, as supported by other monitoring variables and the fact that air is constantly being supplied, these values simply indicate a more reduced environment. Chu (1995) also recorded low ORP values in his ATAD studies at UBC.  As was done for temperature data, ORP was averaged over 12 hour periods for the data tables in Appendix C, while the statistical calculations were performed on the complete data set. Table 4.4 provides a summary of run averages. Run 5 is highlighted, as the sample average does not reflect the oscillating pattern of the data. Values are within the range of full scale facilities and other pilot scale studies (see Section 2.3.3.2)  The increased addition of secondary sludge had a definite impact on ORP values; ORP became more negative with higher proportions of secondary sludge. Figure 4.18 illustrates the reationship. As ORP is most strongly effected by oxygen levels, the secondary sludge can be assumed to be exerting a higher demand than primary sludge. At the same time, the more reduced state of secondary sludge could lower the ORP of the system. Chu (1995) observed ORP to be more sensitive to substrate addition within each run, than to changes in aeration between 0-165 ml/min  55  0 ^-100 o | -200  avg airflow 48 ml/min Control ATAD  j^-300 § -400  Test ATAD  -500 September 11th to 16th  FIGURE 4.12: ATAD ORP Profile, Run 1  0  avg airflow 27 ml/min  Test ATAD  -500 September 27th to October 2nd  FIGURE 4.13: ATAD ORP Profile, Run 2  56  0  avg airflow 41 ml/min  £ -100  -500 October 12th to 17th  FIGURE 4.14: ATAD ORP Profile, Run 3  0  avg airflow 51 ml/min  -w-100 Control ATAD  -500 October 27th to November 1st  FIGURE 4.15: ATAD ORP Profile, Run 4  57  200  -500  — November 20th to 26th FIGURE 4.16: ATAD ORP Profile, Run 5  200  T  100 -  -500 December 2nd to 7th  FIGURE 4.17: ATAD ORP Profile, Run 6  58  TABLE 4.4: AVERAGED ATAD ORP Run  Test Sludge Ratio (primary/secondary)  Control (mV) avg  std dev  Test (mV) avg  Difference  std dev  1  100/0  -243  9  -319  14  76  2  65/35  -255  7  -374  9  119  3  35/65  -262  14  -393  9  131  4  0/100  -275  3  -421  7  146  5  0/100 solubilized  -337  48  -269  in  58  6  35/65 solubilized  -354  15  -433  9  79  j  On-line ORP monitoring was also done by Chu (1995) in his ATAD studies with primary sludge. A characteristic shark-tooth pattern was noticed to coincide with substrate addition to the reactors; at each hourly feeding, an abrupt decrease in ORP was registered, followed by a gradual recovery over the hour in between. Figure 4.19 illustrates the pattern. This same pattern is illustrated in all runs, although not consistently throughout and less pronounced with the scale used in the figures. The test reactor traces in Run 5 and 6 provide the most obvious examples. Mcintosh & Oleszkiewicz (1996) also recorded this pattern with 3 hour feedings, values dropping to -225 mV and recovery to -10 mV. These responses indicate the utility of ORP for monitoring substrate addition.  The extreme oscillations in ORP values in the Test reactor in Run 5 may also be a result of process changes that occurred prior to the test period. In order to provide enough secondary sludge during the last two runs, feeding was stopped for a period of 10 days, to allow reserves to build-up. Thus, the retention time of the material in the reactor was significantly increased. It has been demonstrated that an increase in retention time increases oxygen demand and, as nitrification is inhibited at elevated 59  -300 «  >  >  2  ~-350  R == 0.96  Q_  rr O  CD CD  2 -400 CD > CO  <  /ten  i  0  25 50 75 % secondary sludge  10 0  FIGURE 4.18: Effect of Increased Additions of Secondary Sludge on ORP  b)  ORP Variations, Sides A and B  -320 r Depression of signal  1 fe -410  o .vWVl  -420 00:09:22  00:21:22  01:09:22  Time (days:hours:min)  FIGURE 4.19: Shark Tooth Pattern of ORP in Response to Substrate Addition in ATAD  60  temperatures in TAD, the increased demand is assumed to be the result of increased endogenous respiration (Sucuru et al, 1986). Although the reactors were given 6 days to recover and acclimatize, the additional demand of pre-solubilized feed may not have allowed the test reactor to fully recover. The control reactor was fairly stable, although fluctuations were also recorded. By Run 6, both reactors appear to have stabilized.  4.2.5 Dissolved Oxygen  Dissolved oxygen (DO) levels were below 1 mg/L in all runs. This corresponds to the "oxygen deprived" classification defined by Boulanger (1995). As the accuracy of readings below 1 mg/L are assumed inaccurate, the results will simply be taken as indicating that an oxygen limited state was established in the reactors, and an anaerobic environment was avoided.  4.2.6 Airflow  Airflowrates calculated for the meter readings recorded throughout the process period are presented in Appendix D, along with calculated average, range and standard deviation. As these averages include a period of airflow adjustment where air flow was 800 ml/min, airflow rates were additionally averaged for each run for discussion. Run averages are given in Table 4.21, daily readings for each run are summarized in Appendix C. Since airflow was split after the meter for Runs 1 through 4, the flow rates per reactor are simply half of the total recorded flow.  Due to the discrepancy in calibration curves, highlighted in Section 3.2.5, values can not be accurately compared between Runs 1 to 4, and Runs 5 & 6. Relative comparisons to other variables in this study can be made within these two groupings. Similarly, any established trends can be compared 61  with trends from other research. No comparison of absolute values is possible.  TABLE 4.5: AVERAGE AIRFLOWS Run  Date  Control (ml/min)  Test (ml/min)  1  09/11 -09/16  48  48  12  09/27 - 10/02  27  27  3  10/12 - 10/17  41  41  4  10/27-11/01  51  51  5  11/20-11/26  40  40  6  12/02 - 12/07  41  40  As an indicator that airflow rates were not excessive, no foaming problems were experienced during experimental runs (and installed foam cutters were never operated).  The only period when foam  production was noted was during the aeration studies between Runs 4 and 5, when dissolved oxygen was measured as high as 4 mg/L. One incident of a "foam overflow" occurred during this time, when feeding was reinitiated after the one week build-up period. In ATAD, maintenance of a foam layer is desirable to improve oxygen utilization, enhance bioactivity and provide insulation (Deeney et al., 1991). Excessive foam production is undesirable and has been shown to indicate excessive aeration, thin feed, process upset and changes in the characteristic of the process microorganism, specifically between mesophilic and thermophilic cultures (Kelly et al., 1995). All these factors would account for the foaming events.  62  4.2.7 Air Composition  As compared with ambient air composition at 20% oxygen and 80% nitrogen, headspace gases registered a small percentage of carbon dioxide and corresponding decrease in % oxygen. As illustrated in Figure 4.20, the control reactor tended to have a higher percentage of carbon dioxide than the test reactor, with a maximum of 2.7%. Methane was not detected in the headspace gases in either of the reactors. These results further indicate that an anaerobic environment was not established in the reactors.  In experiments by Boulanger (1995), elevated levels of nitrogen in the off-gases under oxygen deprived conditions was assumed to indicate that nitrification was occurring. This condition was not noticed under similar conditions .  63  AMBIENT AIR r- (0.01%)CQ2 (20.29%) 0 2  N2 (79.70%)  CONTROL ATAD REACTOR (1.57%)C02 (18.35%) 0 2  N2 (80.07%)  TEST ATAD REACTOR (0.65%) C 0 2  19.45%)02  N2 (79.90%  FIGURE 4.20: A T A D Air Composition  64  4.2.8 pH  The contents of the ATAD reactors remained between neutral and slightly acidic pH during nonsolubilized runs, indicating stable operations. Pre-solubilization of sludge feed with 15 meq/L of NaOH resulted in an increase in the pH of the feed. As pH was consumed by the portion of sludge remaining in the feed tanks over the 24 hour semi-continuous feed cycle, and TAD produces alkalinity, the pH of the reactors was less effected. The average pH of the reactor contents during each run is summarized in Table 4.6. The complete data sets are given in Appendix C.  TABLE 4.6: AVERAGE ATAD pH Run  Test Sludge Ratio (primary/secondary)  Control PH  Test PH  1  100/0  6.5  6.7  2  65/35  6.6  6.7  3  35/65  7.0  7.0  4  0/100  7.0  6.9  5  0/100 solubilized  7.2 (feed 6.5)  7.8 (feed 9.7)  6  35/65 solubilized  6.9 (feed 6.4)  7.4 (feed 8.4)  In comparison to previous research, under similar aeration rates and 3 days retention time, Chu (1995) recorded pH readings between 5.5 and 7.5 with primary sludge, and Boulanger (1995) recorded an average pH of 7.0 with 44/56 mix. In Chu's studies, a decrease in pH was noted with decreases in aeration and retention time. His results also suggested that there is a point at which 65  available oxygen is limited and a drop in pH is attributed to VFA accumulation. In studies by Mcintosh & Oleszkiewicz (1996) with primary sludge, no depression of pH was noted with decreases in retention time or the accumulation of VFA.  Similarly, in these studies there is no trend of  increasing pH with increasing VFA accumulation. In a review of full scale operating facilities, Deeney et al. (1991) reports typical pH values for feed and ATAD sludge of 6.5 and 7.2, respectively.  TAD is inherently stable with respect to pH, primarily as a result of inhibition of nitrification. At the same time, ammonia is a principle buffer (Kelly, 1990). In addition, the production of C 0 increases 2  alkalinity in TAD and provides additional buffering capacity for the anaerobic digester in dual digestion systems (Appleton & Venosa, 1986b; Mcintosh & Oleszkiewicz, 1996). The effect of presolubilization with NaOH deteriorates this stability as indicated by the increase in pH in the test reactor in Run 5 & 6, and more clearly in the daily oscillation of pH as illustrated in Figure 4.21. Knezevic (1993) also noted pH increases with pre-solubilization of secondary sludge; however, in subsequent anaerobic digestion, this increase was beneficial, resulting in less frequent buffering requirements.  As pH was only measured every 12 hours, the rate of increase of pH in the feed tanks is not known, nor the time or rate of decrease. Based on the results by Knezevic (1993) on mixing time and presolubilization with this same chemical dose, it is assumed pH rose rapidly during the first 3 to 5 hours, followed by a slow decrease over the remaining holding time in the feed tanks. Therefore, it is assumed the maximum feed pH was not recorded and is slightly greater than the "am" measurement taken 1 hour after the addition of NaOH.  66  2  3  4 Day  5  6  FIGURE 4.21: pH Instability with Pre-solubilization of Feed Sludge  67  4.2.9 Feed Total Solids  Total solids data for the entire experimental period is reported in Appendix E. Overall, average feed to the control reactor was 11.6 g/L (1.2%), slightly higher than the test reactor feed at 11.4 g/L (1.1%). The daily variability between feed streams is illustrated in Figure 4.22. The largest difference between the test and control feed was 13.5 g/L (1.4%), although the majority of the variability is closer to zero. At the same time, it is noted that large differences are usually followed by a negative difference of similar magnitude. This is due to the fact that mix ratios were based on the TS value of the sample taken 24 hours previously resulting in a 24 hour lag in compensation.  As can be seen  from the run averages summarized in Table 4.7, TS is basically consistent in all but Run 5.  Average Difference -0.29  tL  0  J  -iJilLiJi., i| >||i i|f ii |i|.< i'H|I .....L.i.1,.11  ,li  dm  i.  iiiiiiiiiiiiiiiiiiiiiiiiiinmiiiiiuiiiiHiiiiiiiiiiniiiiiiiiiiiiiii miimiiinimmiiiiiiiiiiiMiiiiiniiniiiiimniriMMMH! iiiiiiiiiiniuiii llliiliiuiiiiiiiiiHiiiimiiiniiiiiiiiiiiiiiiiiiimminmiiimnim iinillliiiliiitiiiiimnniininmi  1  08/23 09/06 09/15 09/27 10/05 10/15 10/26 11/03 11/17 11/25 12/05  Date (mm/dd)  FIGURE 4.22: Total Solids Feed Variability  68  TABLE 4.7: AVERAGE FEED TOTAL SOLIDS Run  Test Sludge Ratio (primary/secondary)  Control (%)  Test (%)  1  100/0  1.3  1.3  2  65/35  1.2  1.3  3  35/65  1.3  1.2  4  0/100  1.2  1.1  5  0/100 solubilized  0.8  0.7  6  35/65 solubilized  1.3  1.2  Total solids variability is normal in full scale operating facilities, but was designed as a control for these experiments as it effects digester performance and destruction efficiency (Kelly et al., 1993), and thus could influence V F A At the same time, it needs to be remembered that TS is not a measure of the biodegradable portion of sludge. Although it has been assumed that 55%, of 80% of TS is biodegradable (Gould & Drnevich, 1978), the proportions are not consistent between processes or within processes due to the variability of sewage. Specifically, as there is no grit removal or screening at the pilot plant, it is likely that the primary sludge has a lower biodegradable content than the secondary sludge. Since the mix ratios used in assessment of the effect of secondary sludge are based on the mix ratio of TS, there is the potential that the distinction between the 65/35 and 35/65 mix ratios is not definitive or significant. The ratios could be closer to 50/50 with respect to VS. This point will be referred to in discussions of ATAD performance and VFA enhancement in the following sections.  69  4.3 Total Solids Destruction  ATAD destruction efficiencies are presented in Table 4.8 for all 6 runs. The control reactor was maintained at 100% primary for Runs 1 to 4; however destruction efficiencies rangefroma high of 40% in Run 1, to a low of 25% in Run 3. At the same time, there is a 7% difference between the control and test reactor in Run 1, when both reactors received the same feed. This apparent inherent difference in reactor performance was also recorded by Chu (1995) in parallel experiments with primary sludge. Still, a difference greater than 7% potentially indicates that the addition of secondary sludge reduced destruction efficiencies in Runs 2 and 4, and differences less than 7% with presolubilization indicates enhanced destruction. Comparison of the results to full scale operations and other studies precedes any further discussion of these points.  TABLE 4.8: TOTAL SOLIDS DESTRUCTION EFFICIENCY Run  Test Sludge Ratio (primary/secondary)  Control (%)  Test (%)  1  100/0  40  33  2  65/35  29  18  3  35/65  25  19  4  0/100  26  12  5  0/100 solubilized  12  8  6  35/65 solubilized  16  16  As highlighted earlier, TS represent both biodegradable and non-biodegradable solids and thus the values presented above represent a higher % removal in terms of VS and VSS, by as much as 60%. 70  In comparison to the full scale facilities, as reviewed by Deeney et al. (1991), for systems treating a mixture of primary and secondary sludge, it is expected that VS destruction range between 35 and 45% with 6 days retention time. From actual reported values, a range of 35 - 66% VSS has been demonstrated for mixed sludge feed, and 25 - 40% for 100% secondary sludge feed. Since the reactors in this thesis represent the first stage of a minimum two stage system, comparisons to the first stage is more appropriate. Deeney et al. (1991) generalizes that 60%of VS destruction occurs in thefirstreactor, which would reduce the above reported efficiencies to 21 - 40% TSS for mixed feed, and 15 - 24 % for 100 % secondary sludge within the 3 days retention time in thefirstreactor. Overall, mixed sludge destruction efficiencies are still low.  In comparison to ATP units in dual digestion (generally single stage with retention times less than 3 days), Appleton & Venosa (1986b) summarize that operating systems generally achieve from 10 to 20% VS destruction, prior to anaerobic digestion. This range correlates much more closely to calculated results obtain in this research. In addition, the demonstrated improvement in destruction efficiencyfrom12 % VS at pilot scale to 27% VS at full scale in ATP studies by Fuggle & Spensley (1985) illustrates the effect of scale on TAD performance, and indicates that destruction efficiencies reported for the pilot scale reactors should be lower than reported full scale values.  In comparison to other pilot scale ATAD studies, where low initial feed solids tend to additionally reduce ATAD efficiency, destruction efficiencies are similar. Under the same operating conditions and the same reactors, Chu (1995) achieved 8 - 20% TS (10 - 23% VS) destruction with 100% primary sludge, and Boulanger (1995) achieved 20% VS reduction with a 44/56 sludge mix. Boulanger (1995) also demonstrated that aeration rates, increased to oxygen excess levels, did not effect destruction effeciency. Trim & McGlashan (1984) achieved 23% VSS reduction with 100% secondary sludge versus 27% with 50/50 mix; again, in terms of TS, these destructions are within the 71  range of this work.  The results by Trim & McGlashan (1984) also support the relationship of reduced destruction with increased proportion of secondary sludge. On the other hand, Smith et al. (1975) reported conflicting trends. In initial studies, to achieve the same destruction efficiencies as with 40/60 mixed feed, retention time in the ATAD reactor had to be extended by 5 days when 100% secondary sludge was used. However, when retention time was controlled at 4 days, 33% TSS (40% VSS) reduction was achieved with 100% secondary sludge, while only 26 % TSS (30% VSS) was attained with a 60/40 sludge mix. Similarly, direct comparison of results by Chu and Boulanger indicates that mixed sludge feed gave a higher overall average destruction than primary sludge.  Based on the apparent discrepancies of other researchers and the results of this work, for accurate conclusions to be drawn with respect to the effect of secondary sludge addition on solid destruction efficiency, parallel experiments should be run for each mix ratio in the pilot plant ATAD reactors to eliminate any inherent differences between the reactors. Additionally, measurement of TS, VS and biodegradable VS on both feed and effluent is necessary for accurate assessment of solids destruction and comparison to other research.  With respect to pre-solubilization, Knezevic (1993) noted that, although it did not significantly improve VSS destruction in anaerobic digestion, overall VSS reduction was improved due to the destruction of solids during pre-solubilization itself. No consistent reduction between am and pm samples was recorded in Runs 5 & 6 as a result of pre-solubilization to draw the same conclusion from this work. Again, the apparent difference between the two reactors must be eliminated, or accurately quantified, before further conclusions can be made with respect to the effect of presolubilization on reactor destruction efficiencies. 72  4.4 VFA Production - Mixed Sludge Ratio Runs  VFA were detected in all feed streams and ATAD reactor contents for all runs; however, concentrations did not always increase with digestion.  Secondary sludge appears to dilute the  concentration of VFA in the feed, but overall, it enhanced VFA production in ATAD. Appendix F contains the data presented in the subsequent figures illustrating these trends.  4.4.1 Feed Streams  Figures 4.23 (a) and (b) illustrate the differences in total VFA concentrations of the feed streams through thefirst4 experimental runs. The feed to the control reactor was maintained with 100% primary sludge for all 4 runs and yet, not only did the concentrations vary during the 6 day runs by as much as 188 mg/L, the average concentrations rangedfroma high of 291 mg/L in Run 1, to a low of 169 mg/L in Run 3. This illustrates the natural variability of VFA concentrations in primary sewage sludge and reinforces the need to maintain a control reactor through experimental work.  In comparison, the feed to the test reactor was changed in each run and differences between runs is expected.  Figures 4.23 (b) shows a trend of decreasing VFA concentrations with increasing  proportions of secondary sludge. Average VFA concentration droppedfroma high of 274 mg/L with 0% secondary sludge, to 269 mg/L when 35% was added, to 134 mg/L with 65%, andfinallyto 8 mg/L with 100% secondary sludge. Daily fluctuations in the VFA concentrations in the mixed sludge feed streams parallels the fluctuations recorded with 100% primary sludge in the control reactor, again illustrating the variability of primary sewage sludge. The mixing of primary and secondary sludge appears to enhance fluctuations, as both primary and secondary sludge alone show relatively consistent levels. 73  500 _l  T  400 -  all njns100/0  15) E 300  < 200 I  > 100 0 4 DAY  - Run 1  Run 2 •-• Run 3 ^ Run 4  (a) Control  (b) Test FIGURE 4.23: VFA in Feed, Runs 1 to 4  74  4.4.2 ATAD VFA Production  In the digestion of sludge, VFA are both produced and consumed. The difference between influent and effluent concentrations provides an indication of the net production of VFA. As illustrated in Figure 4.24, 100% primary sludge resulted in less than 125 mg/L net production, and in some cases, net consumption of VFA. In contrast, increases in the proportion of secondary sludge resulted in increased net production of VFA. The highest net production of VFA, close to 1000 mg/L, was obtained with 100% secondary sludge. The same scale is used in bothfiguresto highlight the differences.  75  1000 _,  750  -250  1——^— 1  2 -  Run 1  •  3  1 4 DAY  •—  R u n 2 •- R u n 3  5  • r 6  Run 4  (a) Control  (b)Test FIGURE 4.24: Net VFA Production in ATAD, Runs 1 to 4  76  However, due to the variability of VFA levels between runs in the control streams, assessment of the effect of secondary sludge on VFA production must be done using the differences produced specifically, between the test and control reactor for each run. For this comparison, the concentration of VFA that accumulated in the reactor whether introduced in the feed, or generated as a by-product of ATAD, are used. The differences between the test and control are plotted in Figure 4.25, and secondary sludge still demonstrates enhancement of VFA production in ATAD, with 100% secondary sludge resulting in up to 757 mg/L greater accumulation of VFA.  Although the test reactor exhibited enhanced VFA production in Run 1, when the same feed stream was being introduced to both reactors, subsequent runs exhibited significantly larger differences, eliminating the need to "correct" the data. However, further review of the results of experiments run by Chu (1995) using this same apparatus, indicates that the reactor used for the test experiments in thefirst4 runs does possess some inherent mechanical or physical difference which enhances VFA production over that of the reactor designated the control.  77  TEST - CONTROL |  3 • Run 1  4 DAY Run 2  Run 3  Run 4  FIGURE 4.25: ATAD VFA Accumulation as a result of Mixed Sludge Feed  78  Considering other trends and inconsistencies in the results, Run 4 has a relatively large range of VFA concentrations over the 6 day test period. Initially, levels between 600 and 800 mg/L total VFA, drop off to less than 400 mg/L by the end of day 6. Since the use of secondary sludge was highest during this last run, the consistency of the feed to the test reactor had been generally declining from the beginning of the run and was visibly thin at the end. ATAD is strongly effected by solids feed consistency, and this decrease could have resulted in depressed performance of the test reactor and consequently, reduced VFA production in the last days of Run 4.  At the same time,fromthefigurespresented, it can be seen that the distinction between the 65/35 and 35/65 mix ratios is not definitive. As discussed earlier, this is potentially the result of indistinct differences in mix ratios, with respect to VS and biodegradable material, as calculations are based on TS only. This factor restricts the development of a mathematical relationship between % secondary sludge and enhancement of VFA production, although in reality, one may exist.  Furthermore, the non-distinct relationship between the 65/35 and 35/65 mix ratios may also be a result of differences in aeration levels, since decreases in aeration have been demonstrated to increase VFA production (Chu, 1995). Considering the control reactor, where only 100% primary sludge was used, total VFA concentrations are lower for runs with higher recorded airflow rates. Table 4.9 ranks the data and illustrates the inverse relationship. Therefore, the similarity in VFA concentrations in the test reactor in Runs 2 and 3, even though the mix ratio was adjustedfrom65/35 to 35/65, may be a result of the relatively lower aeration rates in Run 2 enhancing VFA production to levels of Run 3; conversely, Run 3 VFA accumulations may have been inhibited by the higher aeration levels.  Additionally, in support of previous results that indicated 100% secondary sludge resulted in the highest levels of VFA production and accumulation, it is noted that these concentration maximums 79  occurred under one of the second highest aeration rates. Thus, predictions could be made that VFA production in ATAD with 100% secondary sludge would have be even greater if all runs had been maintained at the same aeration level.  TABLE 4.9: AIRFLOW EFFECTS ON VFA ACCUMULATION Control ATAD, 10 0% Primary Sludge Median Total VFA Accumulation (mg/L)  Median Airflow Rate (mL/min)  Highest  57  Run 2  Run 2  26  Lowest  T  44  Run 3  Run 3  41  1  T  34  Run 4  Run 4  50  1  Lowest  - 144  Run 1  Run 1  51  Highest  4.5 VFA Production - Pre-solubilization Runs  V F A were detected in all feed streams and ATAD reactor contents for both runs; however, concentrations did not always increase with digestion. Pre-solubilization appears to "inhibit" the benefit derivedfromthe addition of secondary sludge.  4.5.1 Feed Streams  In non-solubilized feed streams (control feed), the variability of VFA is similar to patterns in the first 4 runs.  Fluctuations appear to be the consequence of variability in primary sludge VFA 80  concentrations, enhanced in mix ratios with secondary sludge, and secondary sludge exhibits relatively, consistent levels of VFA. Overall however, absolute concentrations were lower as compared to the same mix ratios in earlier runs. This run variability is discussed in a later section. Figure 4.26 (a) is a plot of feed concentrations for the control reactor in Runs 5 & 6.  In contrast, Figure 4.26 (b) illustrates the extreme variability in solubilized feed streams (test feed). As a result of pre-solubilization with NaOH, VFA levels increased immediately within the first hour and continued to increase over the holding period in the feed tank. Data points arefromsamples removed and preserved 1 hour and 12 hours after chemical addition. As the analysis of these samples was not completed until after experiments had been completed, no samples of the feed sludge were taken after 24 hours (before addition offreshfeed and solubilization chemicals) to determine if VFA levels continued to increase, level-off or decrease between 12 and 24 hours mixing time.  81  300 250  (non-solubilized feed)  0/100  Run 5 + Run 6  (a) Control  4 DAY Run 5  Run 6  (b)Test FIGURE 4.26: VFA Feed Variability, Runs 5 & 6  82  4.5.2 ATAD VFA Production  Figure 4.27 presents the net VFA production data for Runs 5 & 6. In both the control and test reactors in Run 5, production of VFA was minimal as compared with the levels attained in Run 4 with 100% secondary sludge, and there was a net consumption of VFA with pre-solubilized feed. In Run 6, net production was re-established and VFA concentrations, for both non-solubilized and solubilized feed, are similar to those reached in Run 3 with the 35/65 mix ratio. Both test reactors exhibited the same zig-zag pattern of VFA concentrations as was illustrated in the feed streams, with the same magnitude of fluctuation (different scales used infigures).The impact of NaOH addition is obvious.  As undertaken for Runs 1 through 4, a comparison of the difference between the test and control reactor for each run is required to eliminate sludge variability and allow assessment of the test variable, pre-solubilization in this case. Figure 4.28 is a plot of these differences. Although levels in thefirst3 days would indicate that pre-solubilization did not enhance VFA production, the results from days 4, 5 & 6 present conflicting evidence. With 100% secondary sludge, the reduction in VFA accumulation to below zero indicates pre-solubilization inhibits VFA accumulation. On the other hand, the increase in VFA concentrations with mixed sludge would indicate that VFA accumulation was "eventually" enhanced. Since all runs were acclimatized to new feed conditions for a minimum of 6 days (2 full retention times), these results potentially indicate that this was insufficient time, specifically with the additional impact of pre-solubilization. Other interpretations are also possible. Further discussion of the variability in Run 5 & 6 is presented in the next section.  83  800 600  (non-solubilized feed)  35/65  _j  a> 400 z?  >  200  —A  A  -A  ^  Ar-  fa—  0/100  0  -200 -400 1  3  4 DAY  Run 5  6 Run 6  (a) Control  3  4 DAY Run 5 - ^ Run 6  (b)Test FIGURE 4.27: Net VFA Production, Runs 5 & 6  84  6  TEST - CONTROL 800 600  pre-solubilized mixed sludge  _i •  o) 400  < 2000 E  LL >  -200 -400  pre-solubilized 100% secondary sludge  4  1  DAY  Run 5-»- Run 6  FIGURE 4.28: ATAD VFA Accumulation as a Result of Pre-solubilization  85  4.6 VFA Production - Run Inconsistency  Due to additional experimental variability that resulted from both, the limited capacity of the pilot scale facility, and operational variability that could not be adequately measured, the results of Runs 5 & 6 are discussed separately in this section.  In comparison of the results obtained for the control reactors in Runs 5 & 6 (non-solubilized experiments), to previous runs with the same mix ratios, it can be seen that other variables effected V F A production. Figures 4.29 and 4.30 illustrate the differences between the average VFA concentrations for the same sludge mix ratios in different runs. In Runs 4 & 5, although feed concentrations were similar, accumulations in ATAD in Run 5 were almost zero while, in Run 4, the average concentration was 810 mg/L. There is less inconsistency between Runs 3 & 6 where feed and ATAD VFA concentrations respectively, were within the same range, and the increase of VFA with digestion was relatively the same. The lower ATAD levels in Run 6 can be attributed to the lower feed concentrations.  86  Run 4  1000  Run 5  1000  750  750 + O)  |  500 +  % <  250  500  250 +  feed  ATAD  feed  ATAD  FIGURE 4.29: Run Inconsistency with 100% Secondary Sludge  Run  Run 6  3  600  600  feed  ATAD  feed  ATAD  FIGURE 4.30: Run Inconsistency with 35/65 Mix Sludge Ratio  87  As detailed in the Method and Materials section, in order to secure a sufficient quantity of secondary sludge for Runs 5 & 6, feeding of the reactors was stopped for 10 days, resulting in an increase in reactor retention time. It is possible that, as a result, the process culture was starved and a phase of endogenous respiration or sporulation was stimulated (Sonnleitner & Fietcher, 1983a). As a consequence, upon re-establishing the hourly feeding, the process micro-organisms were initially inhibited with respect to efficient digestion and thus, VFA production. This would explain the larger inconsistency with Run 5 which was initiated just 10 days after the down period, versus Run 6 which had an additional 12 days to recover.  At the same time, wasting rates from the wastewater treatment process were also increased for sludge build-up and, as in the end of Run 4, TS consistency of the feed decreased through Run 5, potentially resulting in decreased digester performance. With a change in the sludge mix ratio to 35/65 in Run 6, the demand on secondary sludge decreased and feed TS recovered to > 1%. In addition, feed VFA concentrations did not similarly increase with the increase in feed TS, supporting the assumption that it was digester performance that was reduced and resulted in reduced VFA production, not a reduction in influent VFA. Average influent levels of VFA dropped from 134 mg/L in Run 3, to 23 mg/L in Run 6 and still 392 mg/L of VFA accumulated during Run 6, as compared with 434 mg/L in Run 3.  During the period prior to Runs 5 & 6, the aeration studies were also carried out and potentially resulted in process upset that required a longer recovery period than was provided. Aeration levels were unexpectedly increased, due to discrepancies in calibration information, and DO levels above 4 mg/L were recorded. Previously all measurements had been < 1 mg/L. Consequently, the mixed culture of aerobic and facultative anaerobic microorganisms could have been shifted towards a predominantly aerobic culture. Treatment efficiencies would have been adversely affected by this 88  shift, as well as by the subsequent shift back to a mixed population with the correction to airflow rates. VFA production would have similarly been depressed for this period, and potentially longer..  In indirect support of this "crash and recovery" theory, is the fact that both reactors appear to have recovered by Run 6. ATAD VFA concentrations are in the range of400 mg/L, as they were in Run 3. Additionally, although the net production in Run 6 was still slightly lower than in Run 3, it could be a result of differences in aeration between Runs 1-4 and Runs 5 & 6, or due to the apparent, inherent, higher production efficiency of the test reactor. No conclusions can be made at this time.  In summary, due to the unstable conditions, particularly obvious in Run 5, conclusions with respect to trends and relationships for the effect of pre-solubilization can not be established from the generated data. In addition, experiments were not rerun to check or correct for the process upset resultingfrompre-solubilization; results with mixed sludge feed were sufficiently positive, and the additional costs and hazards associated with the use of chemicals were seen to outweigh the minimal evidence of VFA enhancement through pre-solubilization.  At the same time, thermophilic  temperatures should result in the lysis of mesophilic substrate microorganisms in the ATAD reactor, and at a fairly high rate. In this context, pre-solubilization is unnecessary and results in an increase in pH and pH variability in a system which has been shown to be inherently stable.  4.7 VFA Speciation  Li all runs, acetate was the predominant species, both in the feed and in the ATAD reactors. Tables 4.10 and 4.11 list the average concentration of the 4 species measured, and the percentage that acetate represents of this total. Looking at the species concentrations in primary sludge, both the streams in Run 1 and the control in subsequent runs, it can be seen that almost the same proportion 89  of the total concentration was represented by propionate. This corresponds to distributions attained in primary sludge fermenters (Chu et al., 1994; Atherton, 1995). Secondary sludge, on the other hand, had a consistently higher percentage of acetate as summarized in the table by the increasing proportion of acetate with each increase in the proportion of secondary sludge in mix ratios. At the same time, secondary sludge was analyzed separately in all runs, and the actual percentage of acetate was consistently high in Runs 1, 2 & 3, at 78%, 82% and 83% respectively.  With the pre-solubilization of sludge feed, acetate remained the predominant species; however, as the addition of NaOH resulted in the production of all 4 species, the actually % of acetate decreased. From the results in Appendix F, it was also observed that all species concentrations followed the daily zig-zag pattern illustrated by total VFA concentrations (see Section 4.5.1). Although the increase in acetate and total VFA concentrations would be beneficial in terms of supplementing Bio-P or anaerobic processes, thefluctuationsmay counteract the derived benefits.  Pre-solubilization of the feed streams did result in the an increase in soluble TP in the 100% secondary sludge feed stream, but did not significantly effect the mixed sludge feed; since mixing of primary and secondary sludge alone results in solubilization of stored phosphorus (Rabinowitz & Barnard, 1995). Figure 4.32 illustrates the different impact of solubilization on the two feed streams.  90  TABLE 4.10: VFA SPECIATION IN FEED SLUDGE Sludge Mix Ratio (primary/secondary)  acetate (mg/L)  propionate (mg/L)  100/0 control  159  119  4  9  55%  100/0 test  152  112  3  7  55%  100/0  118  88  2  5  55%  65/35  155  103  5  6  58%  100/0  92  72  2  4  54%  35/65  96  34  2  2  72%  100/0  97  79  2  4  53%  0/100  7  1  0  0  88%  3  0  0  0  100 %  108  14  5  14  77%  35/65  19  4  0  0  83 %  35/65 pre-solubilized  82  25  4  5  71%  0/100 0/100 pre-solubilized  iso-butyric (mg/L)  butyric (mg/L)  % acetate  TABLE 4.11: VFA SPECIATION IN ATAD propionate (mg/L)  iso-butyric (mg/L)  butyric (mg/L)  % acetate  Sludge Mix Ratio (primary/secondary)  acetate (mg/L)  100/0 control  132  4  12  0  89%  100/0 test  152  4  8  0  93%  100/0  220  33  18  0  81%  65/35  502  33  27  3  89%  100/0  198  13  2  0  93%  35/65  414  13  7  0  95%  100/0  198  4  2  0  98%  0/100  739  48  23  0  91%  31  0  0  0  100 %  4  0  0  0  100 %  35/65  365  8  19  0  93%  35/65 pre-solubilized  404  29  45  0  85%  0/100 0/100 pre-solubilized  91  4.8 Nutrients  Since one purpose of producing VFA in TAD is for recycle and use in BNR processes, investigation of the fate of nutrients is important. The following sections provide a record of phosphorus and nitrogen species. A detailed study of "nutrient fate" was previously done by Boulanger (1995), and is published elsewhere (Boulanger et al., 1994). The results of this study support the conclusion that most biologically stored phosphorus is released under TAD conditions, specifically under the oxygen limited environment established.  4.8.1 Phosphorus  Total phosphorus (TP) was generally conserved between influent and ATAD effluent (assuming small difference are the result of sampling and analytical error), thus allowing comparison of results. TP consistently increased with each addition of secondary sludge, as expected for Bio-P waste activated sludge. Variability in TP levels between the same mix ratios, tested in different runs, was low, except in Run 5 where concentrations were consistently lower.  Ortho-phosphate (P0 ) levels in primary sludge feed were consistent through experiments at 5 mg4  P/L.  Secondary sludge had consistently higher concentrations during thefirst4 runs and resulted  in a gradual increase in P 0 levels in the test feed, as the proportion of secondary sludge was 4  increased. In contrast, the 0/100 non-solubilized stream tested in Runs 5 had lower concentrations of P0 in both feed and ATAD streams, as compared to the same stream in Run 4, while the 35/65 4  non-solubilized stream in Run 6 was higher than the in Run 3. Pre-solubilization of feed resulted in increased P 0 levels in the feed, but levels after digestion were the same. Other than in Run 1, 4  ATAD resulted in an increase in P0 concentrations with all feed sludges. Figure 4.31 is a bar graph 4  92  of average P 0 concentrations in the feed streams and ATAD reactors, exact values are in Appendix 4  G.  Pre-solubilization of the feed streams did result in the an increase in soluble TP in the 100% secondary sludge feed stream, but did not significantly effect the mixed sludge feed; since mixing of primary and secondary sludge alone results in solubilization of stored phosphorus (Rabinowitz & Barnard, 1995). Figure 4.32 illustrates the different impact of solubilization on the two feed streams.  93  250  Feed  ATAD  200 _i  solubilized  CL  6)150 E  gioo CL  50 0  T  1 2 3 4 5 6 1 2 3 4 5 6 Experimental Run Control S Test FIGURE 4.31: Fate of Ortho-Phosphate  Solubilized  0/100  4-  35/65  0/100  TP  soluble TP  FIGURE 4.32: Solubilization of Phosphorus, TP  94  LL  35/65  4.8.2 Nitrogen  TKN was generally conserved between influent and ATAD effluent, and consistently increased with each addition of secondary sludge. Less than complete conservation and recorded increases in TKN potentially could be attributed to sampling and analytical error, as % differences are less than 15% in most cases. Larger differences are associated with Runs 4 and 5, when the high demand for secondary sludge resulted in changes in sludge composition over the test period, and also, with larger concentration, most likely due to the additional errors associated with the dilution of samples. Boulanger (1995) recorded differences in off-gas nitrogen concentrations and attributed greater loses to nitrification/denitrification conversion. No evidence of this conversion was noted in this work. Variability in TKN levels between the same mix ratios, tested in different runs, was low except in Run 5, where concentrations were consistently lower than in Run 4. Again, this can be attributed to the high demand for secondary sludge and resulting decrease in sludge consistency.  Nitrate levels never exceeded 2 mg/L in either ATAD reactor, and were usually below 1 mg/L, confirming that nitrification was inhibited by the thermophilic temperatures maintained throughout the processing period.  Ammonia-N levels increased in the feed streams with increases in the fraction of secondary sludge, although not proportionally. Pre-solubilization of the feed sludge also resulted in increases in ammonia levels. The addition of NaOH resulted in increases within thefirsthour of up to 13 mgN/L, with additional increases, over the next 12 hours, of as much as 60 mg-N/L. Although Knezevic (1993) also recorded increases in N H concentrations with increases in mixing time after NaOH 4  addition, increases were not of the same magnitude. Ammonia-N has been demonstrated to accumulate under the oxygen limited environment in ATAD (Mason et al., 1987b), and in all but the 95  first run, N H accumulated as a result of ATAD treatment. Pre-solubilization resulted in minimal 4  additional increases in N H in the ATAD reactors, as similarly observed for anaerobic digestion of 4  pre-solubilized mixed sludge (Knezevic, 1993). Figure 4.33 is a bar graph of average feed and ATAD concentrations, exact values can be found in Appendix G.  Similar to the solubilization of phosphorus, pre-solubilization of the feed streams resulted in a noticeable increase in soluble TKN with 100% secondary sludge only; with the mixed sludge feed stream, no additional benefits were gained, as the material is solubilized when mixed when mixed with primary sludge..  Figure 4.34 depicts this transformation, using the  calculated for Runs 5 & 6.  96  average  concentrations  350  Feed  ATAD  300 ^ 250 |>200 ^150  solubilized  2 100 50 0  1 2 3 4  5 6 1 2 3 4 5 6 Experimental Run I Control d Test  FIGURE 4.33: Fate of Nitrogen, Ammonia  700 600  0/100  35/65  0/100  35/65  soluble TKN  I TKN  FIGURE 4.34: Solubilization of Nitrogen, TKN  97  4.9 Total Organic Carbon  TOC values confirm that NaOH solubilized the feed streams in Runs 5 & 6. Again, the effects of NaOH addition increased with mixing time; initial elevated TOC concentrations were further increased after 12 hours. Investigations on the effect of mixing time by Knezevic (1993) indicate that the increase is most rapid between 3 and 9 hours for 15 meq/L of NaOH. As illustrated in Figure 4.35,. the difference in TOC levels between the test and control reactors in Runs 1 to 4, also supports the assumption that the mixing of primary and secondary sludges alone results in solubilization of sludge components; however, in addition, the high level of TOC in the test feed in Run 4 indicates that secondary sludge contributed a high portion of solubilized material.  TAD should result in increased solubilization and thus, increased TOC. All runs, except the control reactor in Runs 2 & 3, exhibit this trend. This apparent discrepancies, as well as other small differences, may be a result of the use of average values calculatedfromthe reduced sample size in Runs 1 to 4, or as a result of large multiplication factors required by the analyzer for the high concentrations in the sludge. Appendix H contains the complete data sets of TOC samples used for interpretation of the 6 runs.  In addition, it is interesting to note that pre-solubilization of the feed, in Runs 5 & 6, resulted in a reduction in overall TOC concentrations after digestion. This may be an indication that the addition of NaOH results in precipitation of material in TAD.  98  1400  Feed  ATAD  1200 _ j  1000  E 800  _n  solubilized  I"  I  I " I  1 2 3 4 5 6 1 2 3 4 5 6 Experimental Run I Control n Test FIGURE 4.35: Averaged TOC  99  5.0 SUMMARY  5.1 Operating Conditions  In general, the operating conditions of the pilot scale ATAD reactors were stable throughout the experimental period, except for prior to, and during, Run 5:  • ATAD reactor retention time was maintained at 3 days • Temperatures remained in the thermophilic range between 40 °C and 52 °C • ORP values were consistent and ranged between -200 mV and -450 mV • Airflow rates maintained DO < 1 mg/L and did not produce anaerobic conditions • pH was stable and generally neutral in non-solubilized experiments • Feed solids were maintained consistent with different streams, on average 1.1% TS  Additionally, the control reactor demonstrated an inherent difference from the test reactor with temperature and ORP values always being more positive, even with identical feed.  Although airflow rates were maintained consistent between the test and control reactor, average values were not consistent between runs and potentially effected VFA production.  Resulting TS destruction efficiencies in ATAD were not consistent between runs, and the control reactor exhibited higher efficiency for the same sludge mix ratios. The reduction in TS destruction, with increased proportions of secondary sludge, can not be associated directly with the change in mix ratio due to these differences.  Similarly, the effect of pre-solubilization can not be accurately  assessed in this pilot scale system. 100  The inconsistency of results in Runs 5 may be explained by an overall decrease in secondary sludge consistency and changes in the process culture in ATAD. The pilot plant wastewater treatment process was providing the mixed liquor for the secondary sludge used to feed the ATAD reactors. Although there were no obvious signs of process upset, due to the high wasting rates required to provide enough secondary sludge to the ATAD reactors, the mixed liquor became weaker, thus reducing the available substrate and nutrients for the process micro-organisms. Additionally, prior to receiving this feed, the reactors received no feed for a period of 10 days and may have still been recoveringfroma starvation period. Similarly, as a result of aeration studies during this same period, dissolved oxygen levels were increased to > 4 mg/L, which would have also resulted in a shift in the ATAD process culture; thus, the system may not have fully recovered before Run 5. Evidence to support this theory would normally be a drop in temperature due to reduced biological activity; however, the scale of the process and large energy contribution of the mixing and aeration device are capable of compensating for any loss in biological heat generation.  5.2 Enhancement of VFA Production  From the results presented, secondary sludge definitely enhanced VFA production in ATAD. Both mixed sludge feed and secondary sludge alone resulted in higher production and accumulation of V F A than the primary sludge control. Secondary sludge alone, produced the highest VFA concentrations. No relationship was established between increases in the proportion of secondary sludge and resulting increases in VFA.  In addition, ATAD resulted in consistent predominance of > 85% acetate in total VFA measurements. Feed streams consisting of a proportion of primary sludge demonstrated a co-dominance of acetate 101  and propionate, but were similarly altered in ATAD.  The process upset described in the previous section resulted in inconsistent and low levels of VFA in Run 5.  5.3 Pre-Solubilization  The addition of NaOH was effective in pre-solubilizing secondary sludge, although results also illustrate that the mixing of primary and secondary sludge alone induces solubilization. Although, chemical pre-solubilization of feed sludge increases the concentration of VFA in the feed, it can not be determined what effect this pre-treatment has in ATAD, due to the inconsistencies with Run 5. Experiments were not rerun to check or correct this, since earlier runs provided consistent and positive results. In addition, chemical solubilization would result in additional costs, and increases in storage and handling requirements, in plant operations. Thermophilic temperatures alone cause the lysis of mesophilic substrate microorganisms in TAD; thus, pre-solubilization is unnecessary and introduces additional pH changes to the process affecting reactor stability.  5.4 Nutrients  As previously determined by Boulanger (1995), ATAD results in the release of stored phosphorus. At the same time, the mixing of secondary sludge with primary sludge alone results in a significant release before digestion. Nitrification is inhibited in the thermophilic environment of TAD, allowing ammonia to accumulate. The use of VFA enriched ATAD effluent, in recycle to nutrient removal processes, would require post-treatment of some type.  102  In contrast, in the land application of ATAD sludge, the associated nutrient solubilization correlates with an increase in availability for plants, particularly with nitrogen, through the accumulation of ammonia (Murray et al., 1990). In addition, the inhibition of nitrification in ATAD results in almost no nitrates; however, the conversion of ammonia to nitrates, on-site, can not be ruled out, thus the possibility for groundwater contamination can not be ruled out.  5.5 Phosphorus Release Mitigation  As highlighted by Rabinowitz & Barnard (1995), and by Niedbala (1995) in studies in Penticton, BC, mitigation of nutrient release for supernatant recycle can be achieved with chemical treatment of the return stream. To minimize the requirements of this procedure, effective dewatering before digestion will reduce the volume of digested sludge requiring treatment. In addition, rapid dewatering with aeration will prevent the release of nutrients to the liquid stream, as will thickening primary and secondary sludges separately. Nutrient release may also be reduced by promoting the formation of struvite (MgNH P0 ), without chemical addition. 4  4  Chemical pre-treatment for the precipitation of phosphorus during digestion, as suggested by Niedbala (1995) for anaerobic digestion, does not appear to be an option here considering the effect that NaOH had on the pH stability of ATAD. The use of lime, Ca (OH) , or other chemicals, might 2  prove better than NaOH and could be investigated for use in ATAD.  Additionally, an alternative option may be found in the nuclear power industry. Studies have recently been conducted on the use offilamentousblue-green algae in recycle lines to remove N and P (Radway et al., 1994). The algae was introduced, at the point of dischargefroma thermal process, into a recycle line with extended retention time of 1 day. The algae was then harvested before 103  reproduction to process, and used for reinoculation of the discharge plume. Tested on a range of temperature variations similar to that of TAD effluent, it was found that 82% of P04 and 70% of TP could be removed. Temperaturefluctuations,inherent in uncontrolled cooling, had minimal effects on efficiency.  5.6 Alternative Applications  As highlighted in the review of thermophilic aerobic digestion, ATP in dual digestion has demonstrated to improve anaerobic digester performance. Since VFA, specifically acetate, are utilized in methanogenic reactions, the demonstrated enhancement of VFA production could also be applied in further enhancement of anaerobic digestion. Chu (1995) proposes that the syntropic relationship between acetogenic and methanogenic reactions could be uncoupled, to allow for separate and complete optimization of methanogenic reactions.  Land application of the ATAD digested sludge can also be considered,  as a result of the  pasteurization effects of TAD, as well as the demonstrated increase in nutrient availability. Although increased levels of VFA, as produced with the digestion of secondary sludge in ATAD in this research, are considered an indicator of non-stabilized sludge for land disposal, increases in the retention time in ATAD, as a result of both regulatory requirements and the additional retention time of subsequent stages in a full process train, would result in the consumption of VFA.  104  6.0 CONCLUSIONS AND RECOMMENDATIONS  Based on the results of the 6 experiments performed in the pilot scale ATAD units at UBC, the following conclusions are made in response to project objectives:  1.  Secondary sludge enhances VFA production and accumulation in TAD, in comparison to primary sludge alone.  2.  Secondary sludge alone, enhances VFA production and accumulation in TAD, in comparison to primary sludge, or to a mix of primary and secondary sludge.  3.  Pre-solubilization of secondary sludge with NaOH increases VFA production in feed sludge (undigested); however, no conclusions can be drawn with respect to TAD.  4.  Chemical pre-solubilization of feed produces fluctuations in ATAD operating parameters.  5.  TAD consistently results in > 85% acetate with respect to total VFA production.  6.  Pre-solubilization with NaOH results in solubilization of substrate, particularly the release of stored phosphorus.  7.  Mixing of primary and secondary sludge results in solubilization of substrate, particularly the release of stored phosphorus.  8.  TAD results in additional solubilization and release of phosphorus.  9.  TAD results in inhibition of nitrification and accumulation of ammonia.  10.  Pre-solubilization with NaOH results in reduced overall solubilization of TAD effluent, as measured by TOC.  105  In addition, the following conclusions were made, based on analysis of other parameter measured in the study, as well as observations of process operations:  •  Variations in airflow rates, within the oxygen limited aeration state established, appear to effect VFA production - lower airflow rates produce higher VFA concentrations.  •  Changes in mixed liquor and secondary sludge quality (thinner and weaker) and increases in aeration to aerobic levels, results in process upset of ATAD.  •  Inherent differences appear to exist between the two ATAD reactors effecting temperature, ORP and solids destruction.  Based on these conclusions and the results of this study, the following recommendations are made:  1.  No further investigation of pre-solubilization with NaOH.  2.  Pilot and full scale investigation of the impact of using VFA enriched TAD effluent for recycle to BNR processes.  3.  Investigation into the impact of post-treatment of TAD effluent for mitigation of nutrient loading to BNR processes.  4.  In future research, more accurate control and measurement of airflow rates to eliminate any secondary effects in assessment of other variables.  5.  Li future research and evaluation of ATAD facilities, determination of VS and VSS, in addition to TS, to more accurately assess treatment efficiency.  6.  With respect to UBC's pilot plant ATAD unit, confirmation and quantification of inherent differences in operating performance.  106  REFERENCES  American Public Health Association, American Water Works Association, and Water Pollution Control Federation (1989), Standard Methods for the Examination of Water and Wastewater, 18th edition, APHA, AWWA & WPCF, Washington, DC, USA. Anderson, B.C. and Mavinic, D.S. 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(1983b), Bacterial Diversity in Thermophilic Aerobic Sewage Sludge, II. Types of Organisms and Their Capacities, Eur. J. Appl. Microbiol. Biotechnol., 18:174180. Sonnleitner, B. and Fiechter, A. (1983c), Thermophilic Microflora in Aerated Sewage Sludge, Processing and Use of Sewage Sludge, Proceedings of the Third International Symposium, Commission of the European Communities, September 27-30, 1983, Brighton, p.235-236. Sonnleitner, B. and Fiechter, A. (1985), Microbial Flora Studies inThermophilic Aerobic Sludge Treatment, Conservation & Recycling, 8 (1-2):303-313.  Strauch, D., Hammel, H-E. and Philipp, W. (1985), Investigations of the Hygienic Effect of Single Stage and Two-Stage Aerobic-Thermophilic Stabilization of Liquid Raw Sludge, Inactivation of Micro-organisms in Sewage Sludge by Stabilization Processes, Elsevier Applied Science, New York, USA, p. 48-63. Surucu, G. A , Chian, E.S.K. and Engelbrecht, R.S. (1976), Aerobic Thermophilic Treatment of High Strength Wastetwaters, J. WPCF, 48(4):669-679. Trim, B.C. and McGlashan J.E. (1984), Sludge Stabilisation and Disinfection by Means of Autothermal Aerobic Digestion with Oxygen, Wat. Sci. Tech., 17:563-573. Tyagi, R.D., Tran, F.T. and Agbebavi, T.J. (1990), Mesophilic and Themophilic Aerobic Digestion ofMunicipal Sludge in an Airlift U-Shaped Bioreactor, Biological Wastes, 31:251-266.  U.S. EPA (1990)^ Autothermal Thermophilic Aerobic Digestion ofMunicipal Wastewater Sludg Environmental Regulations and Technology, Cincinnati, OH, EPA/625/10-90/007, September. Vismara, R. (1985), A Model for Autothermic Aerobic Digestion: Effects of Scale Depending on Aeration Efficiency and Sludge Concentration, Water Research, 19(4):441-447.  Ill  Wolf, P. (1982), Aerobic Thermophilic Stabilization of Sludge Versus Anaerobic Digestion and Other Kinds of Sludge Treatment atMiddle-Sized Plants with Respect to Power Conservation Economy, Wat. Sci. 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(1985), Aerobic-Thermophilic/Anaerobic-Mesophilic Two-Stage Seage Sludge Treatment: Practical Experiences in Switzerland, Conservaton & Recycling, 8 (l-2):285-301.  112  APPENDICES  113  APPENDIX A: ABBREVIATIONS  A- 1  ATAD ATP AVG BC C C H or CH4 C 0 or C02 DO L MAX meq/L MTN ML mL NaOH N H or NH4 NO orNOx N orN2 0 or 02 P 0 or P04 STDS T TAD TKN TOC TP TS UBC VFA VS VSS  autothermal thermophilic aerobic digestion aerobic thermophilic pretreatment average British Columbia, Canada control feed/reactor menthane carbon dioxide dissolved oxygen litre maximum milliequivalen per litre minimum mixed liquor millilitre sodium hydroxide ammonia nitrogen nitrate and nitrite nitrogen nitrogen (gas) oxygen ortho-phosphate (soluble phosphorus) standard deviation, sample test feed/reactor thermophilic aerobic digestion total Keidjal nitrogen total organic carbon total phosphorus total solids University of British Columbia volatile fatty acids volatile solids volatile suspended solids  Date 09/02 a 10/17 p  month/day am (ie. September 2nd) month/day pm (ie. October 17th)  Mix Ratio 35/65  35% primary sludge/65% secondary sludge  4  2  4  x  2  2  4  A-2 115  APPENDIX B: PHOTOS  B- 1  FIGURE B l : U B C Pilot Plant Facility (within trailer) with trickling filter tower unit  FIGURE B 3 : Sludge Feed Tanks for A T A D Reactors with mixers  B-3  \\2>  FIGURE B4: A T A D Reactors with Turborator Mixing/Aeration Device (wasting bucket bottom left)  B -4 119  (a) off-gases vented directly to atmosphere  (b) off-gases vented through water trap FIGURE B5: A T A D Reactor Lid showing perforation of Turborator shaft, monitoring probes and air exhaust B-5  \2o  (c) off-gases sampling vial attached to outlet port FIGURE B5: A T A D Reactor Lid showing perforation of Turborator shaft, monitoring probes and air exhaust  B-6  V2l  APPENDIX C: OPERATING DAT A  C-1  122.  hin-incoin h - ko o to in in in in w  h - CD co  w  r ^ . c o r - i - T - T r c M c o o o c M O OCOCOCOCOcOcOCOfcOCOCO O)0)0ocoo)0)cocoo>cocoo)  CO O CO CM  ,"T iri  10 i r i w ^fr Tfr Tj- T*  CM  CD  S f  Er? p? r?l°? 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B CO r - CO CO (O CO IO IO LO CO CO CO CO CO CO  X  ookr krkro to  CD °  °? ^ Q)  CO B ^ CO CM fCOCOCO C O) O) O) O)  r o c o c o c O T r f f c o c o f c o c o  U^  CM  CL  COCOtOCDCOr-CO'tCvjmOlW  ^  kr kr- kr kr kr k- coo) kr o cco p pkr CDco kr kj o kr  1 :| to o E cp 2  C  CO CD  .2  B CD  x e^  =6 Q TO CD 5 [TJ CO Q. 7  uC O  ^ s £ g» g eg >  oo co o o m _E CMr t % tb ^ in oi cb ra T- i(0£  APPENDIX D: AIRFLOW AND AIR COMPOSITION DATA  D- 1 126  AIRFLOW DATA (mL/min) - RUNS 1 to 4 Control pm DATE am DAY 41 09/03 09/04 32 25 34 09/05 28 37 43 09/06 34 53 09/07 55 09/08 55 54 66 09/09 28 62 Run 1 09/10 21 37 1 09/11 57 09/12 46 2 51 53 3 09/13 09/14 51 55 4 50 55 5 09/15 09/16 53 49 6 65 09/17 49 61 09/18 53 61 09/19 59 09/20 53 59 09/21 57 57  Run 2 1 2 3 4 5 6  Run 3 1 2 3 4 5 6  Run 4 1 2 3 4 5 6  AVG STDS MIN MAX MEDIAN  09/23 09/24 09/25 09/26 09/27 09/28 09/29 09/30 10/01 10/02 10/03 10/04 10/05 10/06 10/07 10/08 10/09 10/10 10/11 10/12 10/13 10/14 10/15 10/16 10/17 10/18 10/19 10/20 10/21 10/22 10/23 10/24 10/25 10/26 10/27 10/28 10/29 10/30 10/31 11/01 11/02 11/03 11/04 11/05 11/06  Test am  pm 32 28 37 34 55 54 62 21 46 51 51 50 53 49 53 59 53 57  41 25 34 43 53 55 66 28 37 57 53 55 55 49 65 61 61 59 57  Daily Average Control Test 41 41 29 29 31 31 40 40 43 43 55 55 60 60 45 45 29 29 51 51 52 52 53 53 52 52 51 51 57 57 57 57 60 60 56 56 57 57  55 60 16 28 26 24 27 28 23 28 27 29 31 26 26 24 41 34 34 34 34 37 37 43 43 43 36 38 35 37 65 49 49 47 48 47 47 53 49 53 54 49 53 49 49  60 28 30 25 26 28 32 26 27 26 32 28 32 26 29 37 40 40 47 37 40 49 49 48 43 38 43 37 34 49 49 55 52 50 48 47 53 51 57 55 53 57 53 49 47  55 60 16 28 26 24 27 28 23 28 27 29 31 26 26 24 41 34 34 34 34 37 37 43 43 43 36 38 35 37 65 49 49 47 48 47 47 53 49 53 54 49 53 49 49  60 28 30 25 26 28 32 26 27 26 32 28 32 26 29 37 40 40 47 37 40 49 49 48 43 38 43 37 34 49 49 55 52 50 48 47 53 51 57 55 53 57 53 49 47  57 44 23 27 26 26 29 27 25 27 30 28 32 26 27 30 40 37 40 35 37 43 43 45 43 40 39 37 34 43 57 52 50 49 48 47 50 52 53 54 54 53 53 49 48  57 44 23 27 26 26 29 27 25 27 30 28 32 26 27 30 40 37 40 35 37 43 43 45 43 40 39 37 34 43 57 52 50 49 48 47 50 52 53 54 54 53 53 49 48  41 12 16 65 43  44 12 25 66 47  41 12 16 65 43  44 12 25 66 47  43 11 23 60 43  43 11 23 60 43  D-2  \2f  AIRFLOW DATA (mL/min) - RUNS 5 & 6 Control DATE am pm DAY 47 11/07 255 314 11/08 255 314 132 11/09 113 53 11/10 39 56 11/11 11/12 54 69 64 105 11/13 98 95 11/14 90 111 11/15 110 96 11/16 77 56 11/17 39 11/18 39 40 11/19 39 Run 5 39 11/20 39 1 39 39 2 11/21 41 11/22 39 3 40 4 11/23 40 41 11/24 39 5 39 11/25 39 6 41 38 7 11/26 39 39 11/27 39 39 11/28 41 11/29 39 41 39 11/30 44 39 Run 6 12/01 12/02 39 43 1 44 44 2 12/03 44 41 3 12/04 39 40 4 12/05 12/06 39 40 5 12/07 40 39 6 AVG STDS MIN MAX MEDIAN  Test am 47 255 397 93 100 172 224 208 95 110 81 41 41 41 39 41 39 39 39 39 41 44 38 38 41 39 39 40 43 40 40  Daily Average pm Control Test 255 151 151 285 521 786 397 223 397 89 83 91 161 47 130 236 62 204 224 224 85 95 96 152 113 101 104 96 103 103 66 69 56 41 39 41 41 39 41 40 39 41 40 39 39 39 40 40 39 40 39 39 40 39 41 39 40 41 39 40 44 39 43 41 39 43 41 39 40 44 40 41 40 41 41 39 41 39 41 44 40 41 43 41 41 39 42 42 40 41 40 40 40  66 63 38 314 39  69 63 39 314 41  83 84 38 397 41  107 152 39 786 41  68 57 39 285 40  95 111 39 521 41  50 39 16 314 40  52 39 25 314 43  55 53 16 397 41  65 91 25 786 43  51 36 23 285 43  60 68 23 521 43  ALL DATA COMBINED AVG STDS MIN MAX MEDIAN  D-3 128  Air Flow Runs 1 - 4  70 -,  09/03  09/17  10/01  10/15  10/29  Date (mm/dd) Control = Test I  Air Flow Runs 5 & 6 70  o  LL  n  30 20 -I 11/20  1  1  ;  11/24  1  1  1  11/28  Date (mm/dd)  — Control — Test  D-4 129  1 12/02  1  1 12/06  R E A C T O R H E A D S P A C E / O F F - G A S AIR A N A L Y S I S (% composition) C02 DAY  DATE  ambient  02  (%)  CATAD  TATAD  ambient  CH4  N2 (%)  (%)  CATAD  TATAD  ambient  CATAD  TATAD  (%)  ambient  CATAD  TATAD  Run 4 1  10/27 lab air  2  10/28  3  10/29  4  10/30 lab air  5  10/31 lab air  6  11/01 lab air  79.646  79.756  n.d.  n.d.  n.d.  79.603  79.951  79.904  n.d.  n.d.  n.d.  79.469  80.854  80.450  n.d.  n.d.  n.d.  79.532  80.312  79.986  n.d.  n.d.  n.d.  0.535  0.410  20.408  19.819  19.834  79.445  n.d.  0.576  0.291  20.397  19.473  19.805  n.d.  2.280  1.760  20.351  16.866  17.790 18.615  0.147  n.d.  2.223  1.399  20.468  17.465  n.d.  0.643  0.454  20.438  19.262  19.969  79.562  80.095  79.577  n.d.  n.d.  n.d.  11/02 11/03 lab air 11/04 11/05 11/06 lab air  0.052  0.928  0.434  20.335  18.969  20.155  79.613  80.130  79.371  n.d.  n.d.  n.d.  11/07 lab air  0.042  0.897  0.388  20.371  19.256  20.002  79.587  79.847  79.610  n.d.  n.d.  n.d.  17.704 19.739  18.183  79.610  79.620  80.680  n.d.  n.d.  19.612 19.448  79.613 80.992  79.330 79.956  n.d.  16.308  79.742 80.066  n.d. n.d.  n.d.  n.d.  n.d.  11/08 trailer air  n.d.  2.676  1.137  20.390  11/09 trailer air  0.648  11/10 lab air  n.d. n.d.  2.700  1.058 0.596  20.258 19.934  11/11 trailer air  n.d.  0.654  0.787  20.321  19.431  19.246  79.679  79.915  79.967  n.d.  n.d.  n.d.  11/14 trailer air  n.d.  1.446  0.753  20.074  18.246  19.208  79.926  80.308  80.039  n.d.  n.d.  n.d.  11/15 trailer air  n.d.  1.344  0.485  21.023  19.627  19.946  78.977  79.029  79.569  n.d.  n.d.  n.d.  1.628  0.540  20.454  18.330  19.778  79.489  80.042  79.682  n.d.  n.d.  n.d.  n.d.  11/12 11/13  11/16 trailer air  Run 5  0.057  11/17 trailer air  n.d.  1.387  0.513  20.366  18.306  19.657  79.634  80.307  79.830  n.d.  n.d.  n.d.  11/18 trailer air  n.d.  1.913  0.421  20.196  18.019  19.970  79.804  79.978  79.609  n.d.  n.d.  n.d.  11/19 2  11/20 11/21 trailer air  n.d.  2.537  0.533  20.350  16.849  19.481  79.650  80.613  79.986  n.d.  n.d.  n.d.  3  1  11/22 trailer air  n.d.  1.399  0.579  20.225  18.369  19.405  79.775  80.232  80.016  n.d.  n.d.  n.d.  4  11/23 trailer air  n.d.  1.266  0.699  20.432  18.542  19.221  79.568  80.192  80.080  n.d.  n.d.  n.d.  5  11/24 trailer air  n.d.  1.691  0.882  20.344  17.864  18.914  79.656  80.445  80.204  n.d.  n.d.  n.d.  6  11/25 no air  1.480  0.745  18.339  19.219  80.135  80.036  n.d.  n.d.  n.d.  7  11/26 trailer air  n.d.  1.042  0.347  20.199  19.043  19.835  79.801  79.915  79.818  n.d.  n.d.  n.d.  11/29 lab air  n.d.  20.450  18.755  19.564  79.550  80.038  79.898  n.d.  n.d.  n.d.  n.d.  1.207 1.790  0.538  11/30 lab air  0.457  20.272  17.910  19.519  79.728  80.300  80.024  n.d.  n.d.  n.d.  12/01 lab air  n.d.  1.396  0.588  19.993  18.805  19.541  80.007  79.799  79.871  n.d.  n.d.  n.d.  1  12/02 lab air  n.d.  1.706  0.649  20.285  18.567  19.028  79.715  79.727  80.323  n.d.  n.d.  n.d.  2  12/03 lab air  n.d.  1.660  0.576  20.171  18.296  19.500  79.829  80.044  79.920  n.d.  n.d.  n.d.  3  12/04 no air  2.576  0.485  17.313  19.646  80.111  n.d.  n.d.  n.d.  4  12/05 lab air  1.562  0.556  20.264  18.677  19.735  79.736  79.761  79.869 79.709  n.d.  n.d.  n.d.  19.475  17.508  19.724  80.525  80.145  79.737  n.d.  n.d.  n.d.  n.d.  n.d.  n.d.  11/27 11/28  Run 6  n.d.  5  12/06 lab air  n.d.  2.347  0.539  6  12/07 lab air  n.d.  2.645  0.570  20.134  17.301  19.341  79.866  80.054  80.089  1.574  0.651  20.289  18.353  19.448  79.695  80.069  79.900  0.000  0.000  0.000  0.671  0.315  0.247  0.904  0.521  0.257  0.377  0.287  0.000  0.000  0.000  0.000  0.535  0.291  19.475  16.308  17.790  78.977  79.029  79.330  0.000  0.000  0.000  0.147  2.700  1.760  21.023  19.819  20.155  80.525  80.992  80.680  0.000  0.000  0.000  AVG  0.010  STDS  0.031  MIN MAX  •  ] blank cell, no sample taken n.d.  not detected  D-5  R E A C T O R H E A D S P A C E / O F F - G A S AIR A N A L Y S I S (% composition) C02 DAY  DATE  ambient  (%)  CATAD  02 TATAD  ambient  (%)  CATAD  N2 (%) TATAD  ambient  CATAD  CH4 TATAD  (%)  ambient  CATAD  TATAD  79.756  n.d.  n.d.  n.d.  Run 4 1  10/27 lab air  2  10/28  0.147  0.535  0.410  20.408  19.819  19.834  79.445  79.646  3  10/29  4  10/30 lab air  n.d.  0.576  0.291  20.397  19.473  19.805  79.603  79.951  79.904  n.d.  n.d.  n.d.  5  10/31 lab air  n.d.  2.280  1.760  20.351  16.866  17.790  79.469  80.854  80.450  n.d.  n.d.  n.d.  6  11/01 lab air  n.d.  2.223  1.399  20.468  17.465  18.615  79.532  80.312  79.986  n.d.  n.d.  n.d.  n.d.  0.643  0.454  20.438  19.262  19.969  79.562  80.095  79.577  n.d.  n.d.  n.d.  0.052  0.928  0.434  20.335  18.969  20.155  79.613  80.130  79.371  n.d.  n.d.  n.d.  0.042  0.897  0.388  20.371  19.256  20.002  79.587  79.847  79.610  n.d.  n.d.  n.d.  2.676  1.137  20.390  17.704  18.183  19.739 16.308  19.612 19.448  80.680 79.330  n.d.  20.258 19.934  79.620 79.613  n.d.  1.058 0.596  79.610 79.742  n.d. n.d.  n.d. n.d.  11/02 11/03 lab air 11/04 11/05 11/06 lab air 11/07 lab air 11/08 trailer air 11/09 trailer air 11/10 lab air  n.d. n.d. n.d.  0.648 2.700  80.066  80.992  79.956  n.d. n.d.  11/11 trailer air  n.d.  0.654  0.787  20.321  19.431  19.246  79.679  79.915  79.967  n.d.  n.d.  n.d.  n.d.  n.d.  11/12 11/13 11/14 trailer air  n.d.  1.446  0.753  20.074  18.246  19.208  79.926  80.308  80.039  n.d.  n.d.  11/15 trailer air  1.344  0.485  21.023  19.627  19.946  78.977  79.029  79.569  n.d.  n.d.  n.d.  11/16 trailer air  n.d. 0.057  1.628  0.540  20.454  18.330  19.778  79.489  80.042  79.682  n.d.  n.d.  n.d.  11/17 trailer air  n.d.  1.387  0.513  20.366  18.306  19.657  79.634  80.307  79.830  n.d.  n.d.  n.d.  11/18 trailer air  n.d.  1.913  0.421  20.196  18.019  19.970  79.804  79.978  79.609  n.d.  n.d.  n.d.  11/19  Run 5 1 2  11/20 11/21 trailer air  n.d.  2.537  0.533  20.350  16.849  19.481  79.650  80.613  79.986  n.d.  n.d.  n.d.  3  11/22 trailer air  n.d.  1.399  0.579  20.225  18.369  19.405  79.775  80.232  80.016  n.d.  n.d.  n.d.  4  11/23 trailer air  n.d.  1.266  0.699  20.432  18.542  19.221  79.568  80.192  80.080  n.d.  n.d.  n.d.  5  n.d.  1.691  0.882  20.344  80.204  80.135  80.036  n.d. n.d.  n.d. n.d.  n.d.  7  11/26 trailer air  n.d.  1.042  0.745 0.347  18.914 19.219  80.445  1.480  17.864 18.339  79.656  6  11/24 trailer air 11/25 no air  20.199  19.043  19.835  79.801  79.915  79.818  n.d.  n.d.  n.d.  11/29 lab air 11/30 lab air 12/01 lab air  n.d.  1.207  0.538  20.450  18.755  19.564  79.550  80.038  79.898  n.d.  n.d.  n.d.  n.d.  1.790  0.457  20.272  19.519  79.728  80.300  80.024  n.d.  n.d.  n.d.  n.d.  1.396  0.588  19.993  17.910 18.805  19.541  80.007  79.799  79.871  n.d.  n.d.  n.d.  1  12/02 lab air  n.d.  1.706  0.649  20.285  18.567  19.028  79.715  79.727  80.323  n.d.  n.d.  n.d.  2  n.d.  1.660  0.576  20.171  18.296  19.500  79.829  80.044  79.920  n.d.  n.d.  n.d.  3  12/03 lab air 12/04 no air  2.576  0.485  17.313  19.646  80.111  79.869  n.d.  n.d.  n.d.  4  12/05 lab air  n.d.  1.562  0.556  20.264  18.677  19.735  79.736  79.761  79.709  n.d.  n.d.  n.d.  5  12/06 lab air  n.d.  2.347  0.539  19.475  17.508  19.724  80.525  80.145  79.737  n.d.  n.d.  n.d.  2.645  0.570  20.134  17.301  19.341  79.866  80.054  80.089  n.d.  n.d.  n.d.  n.d.  11/27 11/28  Run 6  6  12/07 lab air  n.d.  AVG  0.010  1.574  0.651  20.289  18.353  19.448  79.695  80.069  79.900  0.000  0.000  0.000  STDS  0.031  0.671  0.315  0.247  0.904  0.521  0.257  0.377  0.287  0.000  0.000  0.000  MIN  0.000  0.535  0.291  19.475  16.308  17.790  78.977  79.029  79.330  0.000  0.000  0.000  MAX  0.147  2.700  1.760  21.023  19.819  20.155  80.525  80.992  80.680  0.000  0.000  0.000  | blank cell, no sample taken n.d.  not detected  D-5  APPENDIX E: TOTAL SOLIDS AND SOLIDS DESTRUCTION DATA  E- 1 132  T O T A L S O L I D S D A T A (91L) - R U N S 1 l o  AVG A V G (%) STDS MIN MAX  11.82 1.18% 3.09 1.30 18.93  4.03 0.40% 0.56 0.77 4 73  I  2.98 0.30% 0.66 1.93 4.17  11.93 1.19% 3.43 4.74 19.63  11.93 119% 3 13 1.30 18.93  11.90 119% 249 7.04 19.63  8.57 0.867. 1.12 6.03 11.36  no s a m p l e lost s a m p l e 5 hours of pre-mixing before feeding and s a m p l e  E-2  133  9.50 0,95% 1.60 5 95 13.09  AVG  -0.14  STDS MIN MAX  -7.19 13.50  3.00  I F e e d Variability | T-C Feed  AVG A V G (%) STDS MIN MAX  8.88 0.89% 2.84 4.82 14.45  4.79 048% 0 52 2.84 5.79  4.01 0.40% 0.45 3.45 4.99  10.50 1 05% 3.99 0.00 18.60  11.50 1,15% 3.19 1.30 18 93  4.26 0.43% 0.65 0.77 5.79  3.54 035%, 0.76 1.93 4 99  11.46 1 15% 3.67 0.00 19.63  9.74 097%,  4.42 0.00 15.67  8.93 0.89% 4.33 0.00 15.64  11.13 1.11% 3.80 0.00 18.93  10.90 1.09% 3.50 0.00 19.63  8.98 0.90% 1.29 6.03 11.57  9.51 0.95%  1.25 7.26 11.57  9 43 A V G 0.95% 1 63 S I U S 6,66 MIN 12.15 M A X  ALL DATA COMBINED AVG A V G (%) STDS MIN MAX  no s a m p l e lost s a m p l e 5 hours of pre-mixing before feeding and s a m p l e  E-3 12*  9,49 0 95% 1.61 5.95 13.09  AVG BIDS MIN MAX  T O T A L S O L I D S D E S T R U C T I O N D A T A (g/L) - R U N S 1 to 4 Run Control Control TS Destruction A v e r a g e ATAD Day Date Feed 08/23 08/24 08/25 08/26 08/27  8.00 7.62 10.97 9.64 7.16  08/28  9.01 9.59  08/29 08/30 08/31 09/01  9.19 14.96 12.94  09/02  10.99  09/03  13.30  09/04 09/05  11.38 15.42  09/06  13.73 17.08  09/07 09/08 09/09 09/10  14.65 13.24 16.23  1  09/11  13.31  2 3  09/12 09/13 09/14 09/15 09/16  13.27 14.80 13.41  09/18  8.18  09/19  9.20 10.77  Run 1  4 5 6  pre R u n 2  09/19 09/20 09/21 09/22 09/23 09/24  Run 2 1 2 3 4 5 6  Run 3 1 2 3 4 5 6 pre R u n 4  12.47 13.74 15.54 11.35  09/27 09/28 09/29 09/30 10/01 10/02  13.63 10.87 11.35 10.42  10/04  9.97 9.19  10/05  4.43  10/06 10/07 10/08 10/09 10/10  10.21 10.55  10/11 10/12 10/13 10/14 10/15 10/16 10/17  22% 19% 32% 30% 27% 28% 19%  16.26 10.90 12.11 10.13 14.96 12.99  10/20 10/21 10/22 10/23 10/24  1.39 15.51 15.77  6.89 6.82  21% 15%  7.18  16% 22%  7.53  33%  11.66 12.23  7.60 6.65  39% 49%  11.00 11.40  7.42 6.87  7.84  37% 44%  11.97 13.98  7.24  39%  14.17 12.83  8.24 9.26  13.54 13.49 16.94  8.69 8.48 8.90  13.72  8.43  12.73 12.72 12.13 11.64  8.90 9.17 9.24 9.38  12.23  9.26  9.14 9.67  8.90 8.80  25%  6.61 8.13 8.59 7.94 7.93 8.80  16%  36% 48% 48% 41%  8.60 8.37  41% 41%  8.11 8.24 8.37 8.63  43% 40% 39% 37%  8.08 7.89  38%  7.83 8.58 8.53 8.56 8.61 8.40  26%  11.24 12.24  17% 23% 34% 34% 31% 21%  8.52  24%  9.41 9.62 9.34  20% 31% 31% 30% 31%  9.47 8.29 8.47  40%  29%  29%  7.61 8.09  7.31  24% 36% 41% 37% 36% 34% 31% 36% 37% 33% 43% 40% 37% 29% 25% 24%  33%  18%  13.21 13.85 12.74  9.14 9.67  9% 12%  10.13 10.50  13.73  10.06  17% 20% 24%  11.06 15.68 13.27  10.61 10.13 11.10  12.80  10.79  12.87 13.11 11.49  10.74 10.86 10.61 10.69  12.46 9.88  Run Average  21% 19% 18% 19% 23% 16% 18% 14%  18%  9.56 9.25 9.14 9.84 10.65 10.62 11.47 11.07 9.07 9.91  24%  15.19  20%  9.39 9.01 8.78  30% 31% 21% 24%  10.26 10.39  9.41  25%  18%  9.07 9.68  23%  9.55 9.49 10.14  22% 21% 16%  10.17  17%  13.72 14.60 8.21 9.95 9.79  12.86 12.59 12.36 11.09 10.43  19% 26% 19%  9.81  9.71  -4%  15.42 10.95 11.68 10.11  19%  14.80 8.08 8.32 8.67 17.60 10.17 19.63 17.63  18.93 13.71 14.52 14.69 13.93 13.56 11.53 11.92 12.27  10.69 10.30 10.07 9.83 9.34  25% 28% 28% 24% 24%  11/01  11.75  8.84  26%  11/02  10.94  26%  9% 4%  13.25  AVG STDS MIN MAX •  Test TS Destruction ATAD 6.87 15% 5.95 6.58 11% 24% 6.57 6.56 26%  9.34 10.98  8.11 12.84  4.52 1.75 1.30  6  6.16 6.98 7.80  -  12.35 14.73  10/18 10/18 10/19  2 3 4 5  1  11.87 9.19  09/26  10/25 10/26 10/27 10/28 10/29 10/30 10/31  Run 4  13.34 14.56 10.90  09/25  10/03 pre R u n 3  13.12 13.02  6.47 6.21 6.30 6.03 6.62 6.75  Test Feed 7.04 7.77 11.02 7.90 7.31 9.00  31% 9%  23%  16% 49%  -4% 43%  10%  no s a m p l e  JUJ lost s a m p l e 5 h o u r s of p r e - m i x i n g b e f o r e f e e d i n g a n d s a m p l e  E-4  12%  T O T A L S O L I D S D E S T R U C T I O N S D A T A (g/L) - R U N S 5 & 6 Run Control Control TS Destruction A v e r a g e ATAD Date Feed Day pre R u n 5 (no solubilization  pre R u n 5  11/03 11/04 11/05 11/06 11/07 11/08 11/09  no no no no no no  feed feed feed feed feed feed 15.67  11/10  13.98 9.17  11/11 11/12 11/13 11/14  10.71 11.14 11.42 11.26 11.35 10.86 9.41 9.61  11/15  8.07 13.42 11.20 10.55  11/16  10.27  10.57  11/17 11/18  9.42  8.62  11% 10%  11/23 11/24  8.93  8.29  6 pre R u n 6  11/25 11/26  4 5  8.91 4.36  6  13%  9.15 7.95 7.46 8.12  12%  10.47 11.12 11.63 11.76 12.32 12.33  9.03  13.24  10.32 10.61 10.75  14.21 9.70  12/05 12/06 12/07  14.90  9% 0%  11% 14% 13%  5  12/04  10.92 10.61 10.03  10%  4  13.31 13.51  22% 17%  9.19  9.36  9.02 9.22  2 3  22%  12.12 11.72  14%  11/21 11/22  12/02 12/03  12.02  9.18 9.10  2 3  12/01  11.43  15.64 11.03  11.48 10.10  8.95 8.70 8.41  11/27 11/28 11/29 11/30  15.50  11% 10%  9.73  10.59 10.29 9.64  1  23% 16%  9.21 9.82  11.15 11.44 10.89  18% 15% 16%  13%  16%  19%  8.77  3%  7 83 7.60  9% 7% 6%  7.26  3.91 9.96  6.98  10% 13%  11.89 11.45 11.78  10.01  15%  9.87 10.20 10.39  16%  10.05  15%  13.34 9.28 14.06  9.87  8%  7%  7.90 8.92 8.93 9.43  12.76  17% 16% 16%  9%  9.16  7.40  11.15 11.95  Run Average  10%  10.74  8.59 7.39  11.60 11.71  0% 18% 20%  TS Destruction  12.15 11.80 11.74  11.75 12.37  11/19 11/20  Run 6  28%  Test ATAD  feed feed feed feed feed feed  10% 6%  1  Run 5  Test Feed no no no no no no  20% 22% 19% 15%  15% 18%  AVG STDS  14%  13%  6%  6%  MIN MAX  0% 28%  0% 22%  AVG  25%  20%  STDS MIN MAX  11% 0%  10%  49%  43%  16%  ALL DATA COMBINED  •4%  no s a m p l e lost s a m p l e 5 h o u r s of p r e - m i x i n g b e f o r e f e e d i n g a n d s a m p l e NOTE:  a m a n d p m s a m p l e s w e r e a v e r a g e d to p r o v i d e a 'daily' v a l u e s f o r c a l c u l a t i o n s  E-5  APPENDIX F: VFA DATA  F - 1 13?  « o to —  II  =1= 3-1  p  °l to Sra Kb CN  O  • 11111 c  I a 5  I F-2 \3S  .  CD  tea K —~  <u O  UJ COfO  ,, o k!2  mil iiiig MINI lllll SllSf  at  §6  1Q_  ii nn nn  iggg  F-3 159  Km  =  ON o  fcjmko  lo m  <u O -  IS a:  •a e  F-4 \40  !!!;:::  IIIIII  1 1 1 1 1 1 III! Illl iiii  hrl i; m  I D CDN  a.  §6  E  Hill Hill lllll Hill Hill Hill Hill Hill  ACETIC  o  <  O  6  3 «~  ro ^ro ro in co  ro ^ ro co  1I  1  DATE  Si CN  -J  CO  id  la <  1.007 3.272 ^^^3 2.500 2.100 2.500  m  2.025 4.319 1.900 1.800 3.687  £  5.341  3.162  3.164| 3.041 3.290 3.463 4.394  3.335|  S6  CO  F-6  1*2  11  i-glll T3  E a, S o  o — E - Si is J2 5> c -o  F-7  143  F-8 144  F-9 14S  F - 10  146  F - 11  F - 12  1*8  F - 13  143  APPENDIX G: NUTRIENT DATA  G- 1 ISO  RUN 1 - CONTROL 100/0, TEST 100/0 - NUTRIENT DATA (mg/L as N or P) DAY 1 2 3 4 5 6  DATE 9/11 a P 9/12 a P 9/13 a P 9/14 a P 9/15 a P 9/16 a P  AVG STDS MIN MAX MEDIAN  SETTLED MIXED LIQUOR (Secondary Sludge) NH4  I 131.21 13.32 117.54 148.96 128.16  0.157 0.215 0.000 0.528 0.097  205.49 38.81 146.70 249.29 212.30  5.228 0.683 4.173 5.905 5.269  0.2S3 0.633 0.000 1.416 0  253.19 87 95 207.94 435.68 228.86  119.39 36.43 67.67 149.74 135.69  468.22 222.73 314.21 914.76 395.34  0.316 0.397 0.046 1.028 0.113  37.14 1.75 34.11 39.28 37.44  RUN 1 - CONTROL 100/0, TEST 100/0 - NUTRIENT DATA (mg/L as N or P) CONTROL REACTOR FEED, 100/0 TEST REACTOR FEED, 100/0 DAY DATE TP P04 TKN NOx NH4 TP P04 TKN NOx 1 9/11 a 34.38 5.403 207.86 0.117 26.30 35.13 5.836 245.55 1.162 39.63 6.276 240.30 1.044 29.56 32.22 6.642 203.60 0.874 P 2 9/12 a 30.30 5.689 176.39 0.845 27.65 30.89 6.067 190.20 0.727 30.12 3.467 185.48 0.673 27.81 32.84 4.177 203.01 0548 P 3 9/13 a 31.43 3.251 205.79 0.052 25.28 36.00 3.131 213.20 44.18 3.694 260.27 0.638 25.54 37.53 3.230 245.60 0.624 P 4 9/14 a 22.70 5.628 155.61 0-066 25.62 37.74 5.541 173.03 0 068 26.21 5.717 157.40 26.39 25.67 4.888 135.93 P 5 9/15 a 25.82 4.800 173.10 0.545 24.50 29.34 4.666 180.05 0.610 27.03 4.562 173.58 0.096 23.58 30.54 4.567 177.27 0.055 P 6 9/16 a 26.63 4.312 172.25 0.059 20.94 32.06 4.238 185.19 0.058 31.94 4.145 188.91 0.104 19.43 34.97 4.348 214.20 0.099 P  NH4 26.60 29.32 27.27 30.40 26.38 23.68 24.51 26.27 22.93 21.53 20.41 19.47  lost sample below detection limit (for P04, NOx, NH4) detection limit = 0.05 mg/L (for P04, NOx, NH4)  AVG STDS MIN MAX MEDIAN  30.86 6.14 22.70 44.18 30.21  0.407 0.397 0.025 1.162 0.3235  24.90 3.42 19.47 30.40 25.39  RUN 1 - CONTROL 100/0, TEST 100/0 - NUTRIENT DATA (mg/L as N or P) CONTROL ATAD REACTOR, 100/0 TEST ATAD DAY DATE TP P04 TKN NOx NH4 TP P04 1 9/11 a 42.38 1.644 196.00 0.994 28.00 34.23 3.381 39.32 2.899 180.15 1.107 28.22 38.09 3.371 P 2 9/12 a 38.71 2.992 174.76 1.204 28.23 39.15 3.531 38.63 2.058 178.44 1.160 26.39 39.45 2.263 P 3 9/13 a 39.03 2.195 179.88 0.982 27.01 40.18 2.794 36.11 2.723 168.04 1.186 25.85 40.52 3.280 P 4 9/14 a 30.60 4.567 153.72 0.071 28.29 29.87 5.644 31.89 4.189 181.94 0.066 17.82 34.95 5.211 P 5 9/15 a 28.85 3.180 166.34 0.808 27.94 30.32 3.511 30.08 2.574 171.02 0.251 26.89 30.54 2.861 P 6 9/16 a 30.15 2.447 151.49 0.281 26.68 31.82 2.853 25.40 2.513 146.00 0.309 25.14 29.60 3.080 P  REACTOR, 100/0 TKN NOx 141.68 0.927 173.39 1.241 177.31 1.269 179.76 0.815 183.14 1.245 183.88 1.020 165.81 0.067 195.86 0.075 168.57 0.785 176.91 0.861 175.92 0.332 169.22 1.180  NH4 26.61 27.31 28.03 25.28 25.63 26.74 28.66 30.55 26.60 26.16 24.10 23.98  AVG STDS MIN MAX MEDIAN  174.29 13.07 141.68 195.86 176.42  34.26 5.38 25.40 42.38 34.00  4.745 0.998 3.251 6.276 4.681  2.832 0.839 1.644 4.567 2.6485  191.41 32.10 155.61 260.27 180.93  170.64 14.49 146.00 196.00 172.89  0.357 0.367 0.045 1.044 0.1105  0.702 0.464 0.066 1.204 0.895  25.21 2.85 19.43 29.56 25.58  26.37 2.88 17.82 28.29 26.95  G-2 IS1  32.91 3.56 25.67 37.74 32.53  34.89 4.39 29.60 40.52 34.59  4.778 1.081 3.131 6.642 4.6165  3.482 0.983 2.263 5.644 3.3255  197.23 30.93 135.93 245.60 196.61  0.818 0.437 0.067 1.269 0.894  26.64 1.87 23.98 30.55 26.61  RUN 2 - CONTROL 100/0, TEST 65/35 - NUTRIENT DATA (mg/L as N or P)  AVG STDS MIN MAX MEDIAN  103.37 17.01 92.55 137.40 97.19  0.042 0.028 0.000 0.083 0.0405  155.96 29.04 134.87 213.41 146.56  7.218 0.636 6.089 7.954 7.308  0.064 0.051 0.012 0.140 0.0475  235.01 28.70 202.31 280.05 226.41  132.82 3.03 129.71 136.77 132.24  437.06 60.60 354.30 512.66 422.03  0.867 0.437 0.552 1.618 0.6285  36.47 0.48 36.11 37.35 36.27  TEST REACTOR FEED, 65/35 P04 TKN NOx 43.70 412.18 0.123 48.23 423.70 0.195 56.78 400.50 0.552 79.48 387.50 0.552 50.61 414.60 0.482 47.88 491.88 0.375 57.27 446.20 0.410 60.46 442.55 0.527 46.63 433.13 0.450 49.47 429.00 0.327 48.55 457.25 0.367 53.99 444.65 0.445  NH4 29.89 34.91 30.70 33.58 29.51 29.36 31.45 35.63 28.73 29.40 28.91 35.47  lost sample below detection limit (for P04, NOx, NH4) detection limit = 0.05 mg/L (for P04, NOx, NH4)  RUN 2 - CONTROL 100/0, TEST 65/35 - NUTRIENT DATA (mg/L as N or P) CONTROL REACTOR FEED, 100/0 (Primary Sludge) DAY DATE TP P04 TKN NOx NH4 1 9/27 a 29.63 7.912 164.87 0.786 16.30 42.72 5.257 209.91 0.128 21.62 P 2 9/28 a 31.67 3.915 165.87 0.058 18.33 35.34 5.132 181.64 0.113 21.69 P 3 9/29 a 45.53 4.400 245.43 0.579 20.21 38.90 5.020 226.77 21.45 P 4 9/30 a 36.87 4.346 203.01 0.067 19.57 30.84 4.489 179.37 0.072 21.04 P 5 10/01 a 35.63 4.410 185.33 0.188 21.16 42.26 4.445 205.65 0.690 21.78 P 6 10/02 a 37.94 4.443 198.20 0.618 21.23 41.64 4.674 232.70 0.684 23.00 P  0.400 0.135 0.123 0.552 0.4275  31.46 2.69 28.73 35.63 30.30  RUN 2 - CONTROL 100/0, TEST 65/35 - NUTRIENT DATA (mg/L as N or P) CONTROL ATAD REACTOR, 100/0 TEST ATAD DAY DATE TP P04 TKN NOx NH4 TP P04 1 9/27 a 52.46 8.380 205.43 2.331 56.85 151.45 63.61 46.19 6.230 256.80 0.130 51.95 132.33 60.67 P 2 9/28 a 43.35 6.251 237.51 0.178 56.28 104.05 42.45 46.67 5.173 236.21 0.726 52.86 154.88 63.84 P 3 9/29 a 43.49 5.521 228.99 0.330 52.26 172.90 66.31 51.95 8.844 239.10 0.219 60.55 180.08 64 45 P 4 9/30 a 54.62 5.200 257.42 0.261 52.47 159.63 62.59 49.55 5.717 258.26 0.242 52.19 150.30 56.22 P 5 10/01 a 43.38 5.678 217.55 1.076 50.90 151.85 68.40 43.64 5.717 226.89 1.039 48.80 70.43 P 6 10/02 a 38.64 6.721 204.98 1.317 56.23 166.83 73.01 38.52 5.430 200.40 1.098 49.43 146.83 P  REACTOR, 65/35 TKN NOx 438.48 0.524 381.58 0.297 337.95 0.440 445.95 0.291 488.63 0.505 512.10 0.222 463.98 0.509 420.40 0.402 404.13 0.470 0.549 443.40 0.440 388.23 0.236  NH4 145.24 142.43 109.24 143.61 146.02 143.28 144.76 146.73 139.16 145.17 156.22 148.70  AVG STDS MIN MAX MEDIAN  429.53 50.16 337.95 512.10 438.48  142.55 11.27 109.24 156.22 144.97  AVG STDS MIN MAX MEDIAN  37.41 5.07 29.63 45.53 37.40  46.04 5.22 38.52 54.62 44.91  4.870 1.030 3.915 7.912 4.467  6.239 1.200 5.173 8.844 5.717  199.89 25.88 164.87 245.43 200.60  230.79 20.69 200.40 258.26 232.60  0.362 0.302 0.058 0.786 0.1205  0.750 0.656 0.178 2.331 0.528  20.61 1.81 16.30 23.00 21.19  TP 149.50 134.33 153.03 147.48 145.03 164.88 162.95 158.00 163.60 157.03 158.50 156.85  53.40 3.42 48.80 60.55 52.37  G-3 162-  154.26 8.92 134.33 164.88 156.94  151.92 20.56 104.05 180.08 151.85  53.59 9.53 43.70 79.48 50.04  62.90 8.20 42.45 73.01 63.72  432.34 27.76 387.50 491.88 433.55  0.407 0.116 0.222 0.549 0.44  RUN 3 - C O N T R O L 100/0, TEST 35/65 - NUTRIENT DATA (mg/L as N or P) UNSETTLED MIXED LIQUOR (am, a-Side & pm, B-side) P04 NOx NH4 DAY DATE TKN TP 187.521 0.0571 10/12 a 107.931 10/13 a 3 4 5 6 AVG STDS MIN MAX MEDIAN  r  10/14 a P 10/15 a P 10/16 a P 10/17 a P  159.17  6.0391  r, n*  196.05 141.03 189.20 157.40 191.25 172.80 213.92 181.34  7.009 0.202 8.595 0.803 5.866 0.928 7.108 1.058  0.020 0.026 0.000 0.060 0.003  178.97 21.56 141.03 213.92 184.43  4.532 3.352 0.202 8.595 5.9525  98.46 115.97 49.41 115.61 59.85 119.00 70.31 131.31 76.95 94.48 28.25 49.41 131.31 103.19  0.034 0.004 0.047 0.000  0.101 13.327 0.113 13£91 12.503  _____  5.248 6.724 0.000 13.591 0.107  229.691  1391  469.091  0.112|  36.65  171..  125.11  311.33  0.155  32.51  328.05  122.77  705.79  0.152  29.39  305.85  149.42  761.06  0.095  34.71  263.89 182.06 218.44 250.01  129.26 127.82 135.54 137.77  487.84 326.25 426.34 478.65  0.117 0.162 0.131 0.112  30.15 30.77 29.38 33.45  243.67 55.16 171.34 328.05 239.85  133.46 8.89 122.77 149.42 132.40  495.79 161.75 311.33 761.06 473.87  0.130 0.024 0.095 0.162 0.124  32.13 2.67 29.38 36.65 31.64  lost sample below detection limit (for P04, NOx, NH4) detection limit = 0.05 mg/L (for P04, NOx, NH4)  RUN 3 - CONTROL 100/0, TEST 35/65 - NUTRIENT DATA (mg/L as N or P) CONTROL REACTOR FEED, 100/0 (Primary Sludge) DATE TP P04 TKN NOx NH4 DAY 1 10/12 a 37.73 4.993 240.48 0.763 18.81 48.62 8.180 284.88 0.872 24.73 P 2 10/13 a 31.53 4.042 187.37 0.936 16.98 40.94 4.691 233.24 0.798 18.16 P 10/14 a 36.29 4.447 199.47 0.058 17.31 3 38.82 6.932 214.83 0.797 22.41 P 10/15 a 31.77 4.276 190.56 0.728 18.09 4 38.91 5.068 224.18 0.930 19.36 P 5 10/16 a 52.91 4.558 266.43 0.707 18.97 48.35 5.925 268.73 CL560 21.54 P 6 10/17 a 44.90 5.568 267.29 20.69 44.27 4.675 233.15 0.066 22.50 P AVG STDS MIN MAX MEDIAN  41.25 6.71 31.53 52.91 39.92  5.280 1.215 4.042 8.180 4.842  234.22 32.63 187.37 284.88 233.19  0.604 0.347 0.037 0.936 0.7455  19.96 2.40 16.98 24.73 19.17  TP 307.84 311.36 232.95 164.40 197.74 202.39 349.65 334.76 201.15 192.04 287.89 236.81 251.58 63.37 164.40 349.65 234.88  TEST REACTOR FEED, 35/65 P04 TKN NOx 93.41 777.00 0.091 98.67 800.63 0.207 80.30 593.33 0.127 83.10 410.44 0.118 84.81 435.00 0.147 84.72 490.69 0.164 105.93 855.56 0.115 115.38 837.30 0.125 72.08 543.56 0.083 72.76 535.50 0.124 92.22 717.04 0.154 103.44 530.25 0.087 90.57 13.42 72.08 115.38 88.52  RUN 3 - CONTROL 100/0, TEST 35/65 - NUTRIENT DATA (mg/L as N or P) TEST AT/ \D c ONTROL f iTAD REA(iTOR, 100 0 P04 NH4 TP TKN NOx P04 DATE DAY TP 1 10/12 a 40.53 7.844 221.76 0.930 55.20 184.20 103.01 46.80 9.247 241.59 0.811 61.44 265.80 113.06 P 2 10/13 a 58.52 15.262 272.40 0.970 72.22 243.86 115.61 50.73 11.200 283.89 0.151 72.79 223.39 120.42 P 3 10/14 a 62.21 16.850 292.83 0.196 77.04 205.95 118.45 49.77 10.727 272.15 0.801 70.08 205.88 107.08 P 4 10/15 a 47.36 10.906 262.25 0.853 72.16 257.93 111.27 47.72 11.199 255.83 0.186 68.43 227.85 118.63 P 5 10/16 a 51.32 12.638 243.63 0.913 68.84 318.64 125.46 58.44 10.231 271.41 0.199 92.63 294.38 127.13 P 6 10/17 a 65.57 11.719 299.34 0.848 68.00 309.98 119.63 58.31 9.528 287.27 0.863 80.3: 225.68 124.43 P AVG STDS MIN MAX MEDIAN  53.10 7.40 40.53 65.57 51.02  11.446 2.507 7.844 16.850 11.0525  267.03 23.10 221.76 299.34 271.78  0.643 0.343 0.151 0.970 0.8295  71.60 9.32 55.20 92.63 71.12  G-4 I S3  246.96 43.20 184.20 318.64 235.86  117.02 7.37 103.01 127.13 118.54  627.19 161.07 410.44 855.56 568.44  NH4 32.27 36.52 28.74 28.79 27.41 29.62 31.66 36.22 25.94 28.65 28.82 31.30  0.129 0.036 0.083 0.207 0.1245  30.49 3.27 25.94 36.52 29.22  REACT DR, 35/65 TKN NOx 434.59 0.159 660.64 0.184 630.04 0.200 594.49 0.221 535.43 0.232 516.60 0.229 661.16 0.236 590.81 0.246 776.86 0.217 747.23 0.298 777.53 0.210 591.86 0.364  NH4 130.85 138.05 125.21 158.42 139.62 137.54 132.01 138.53 149.77 150.43 149.83 150.67  626.44 105.77 434.59 777.53 612.26  141.74 9.98 125.21 158.42 139.08  0.233 0.053 0.159 0.364 0.225  RUN 4 - CONTROL 100/0, TEST 0/100 - NUTRIENT DATA (mg/L as N or P)  AVG STDS MIN MAX MEDIAN  139.55 10.68 125.81 152.55 140.20  0.051 0.034 0.000 0.084 0.066  225.70 19.97 200.79 251.52 225.86  8.340 0.941 7.071 9.801 8.3085  0.013 0.016 0.000 0.036 0.0125  103.99 19.37 67.29 117.59 110.56  0.043 0.100 0.000 0.246 0.0015  239.16 38.62 162.80 262.98 254.72  1.667 0.320 1.256 2.008 1.706  9.111 6.936 0.000 15.545 13.9775  RUN 4 - CONTROL 100/0, TEST 0/100 - NUTRIENT DATA (mg/L as N or P) CONTROL REACTOR FEED, 100/0 TEST REACTOR FEED, 0/100 DAY DATE TP P04 TKN NOx NH4 TP P04 TKN NOx 1 10/27 a 39.66 4.430 221.55 1.014 20.16 355.95 150.18 746.80 0.051 37.07 5.881 212.58 0.831 24.82 433.55 166.54 914.70 0.146 P 2 10/28 a 42.51 4.680 244.47 0.901 20.43 328.35 132.40 657.10 0.091 41.51 7.683 238.53 0.960 26.07 400.15 170.51 859.85 0.098 P 3 10/29 a 36.86 4.180 210.66 0.923 20.66 262.55 122.90 477.25 0.086 5.261 0.899 22.83 309.80 137.78 591.00 0.199 P 4 10/30 a 51.02 4.465 261.75 0.971 21.74 314.90 127.82 582.55 0.096 41.01 5.682 230.67 1.027 23.72 340.00 160.83 671.45 0.114 P 5 10/31 a 41.55 4.595 225.24 0.985 21.91 318.55 130.72 618.55 0.105 39.35 5.374 223.85 0.764 23.59 294.40 157.11 562.10 0.146 P 6 1101 a 46.59 4.258 247.82 0.879 20.85 310.15 125.21 627.95 0.128 57.14 5.192 290.42 0.805 22.94 284.35 51.62 567.25 0.175 P  NH4 35.07 38.53 32.40 35.00 28.08 30.09 27.54 30.82 26.55 30.39 26.63 30.42  lost sample below detection limit (for P04, NOx, NH4) detection limit = 0.05 mg/L (for P04, NOx, NH4)  AVG STDS MIN MAX MEDIAN  43.11 6.19 36.86 57.14 41.51  0.120 0.041 0.051 0.199 0.1095  30.96 3.72 26.55 38.53 30.40  RUN 4 - CONTROL 100/0, TEST 0/100 - NUTRIENT D A T A (mg/L as N or P) C ONTROL t \TAD REA( ;TOR, 100 0 TEST AT/ \D NOx TP P04 DAY DATE TP P04 TKN NH4 1 10/27 a 50.97 8.687 264.60 1.104 82.77 342.75 225.34 56.60 15.060 243.87 0.968 84.77 293.40 218.44 P 2 10/28 a 79.73 20.675 310.77 0.960 93.02 365.35 217.99 49.01 11.027 264.77 0.966 75.99 373.35 207.79 P 3 10/29 a 53.84 11.966 255.84 0.967 75.81 433.85 214.79 55.55 9.650 272.27 1.124 76.26 434.85 216.61 P 4 10/30 a 65.51 13.680 298.73 0.941 77.94 330.15 210.39 64.02 15.490 281.66 0.924 81.15 365.55 205.99 P 5 10/31 a 53.19 13.048 255.08 0.915 79.64 360.80 208.94 53.22 11.539 263.21 0.206 75.66 337.15 207.59 P 6 1101 a 66.41 16.314 285.20 0.926 83.07 266.55 208.51 60.24 15.065 268.77 1.030 80.18 356.65 209.28 P  REACT OR, 0/100 TKN NOx 801.00 0.608 653.25 0.746 819.55 0.552 875.30 0.325 942.70 0.516 976.85 0.568 744.80 0.401 841.55 0.515 812.20 0.526 769.15 0.449 553.80 0.412 762.05 0.464  NH4 247.32 252.41 252.32 260.61 269.32 275.80 263.06 264.38 254.78 246.79 24.53 248.03  AVG STDS MIN MAX MEDIAN  796.02 115.59 553.80 976.85 806.60  238.28 67.94 24.53 275.80 253.60  59.02 8.68 49.01 79.73 56.07  5.140 0.979 4.180 7.683 4.936  13.517 3.286 8.687 20.675 13.364  237.05 23.50 210.66 290.42 230.67  272.15 19.18 243.87 310.77 266.77  0.913 0.083 0.764 1.027 0.912  0.919 0.235 0.206 1.124 0.963  22.48 1.86 20.16 26.07 22.37  80.52 5.03 75.66 93.02 79.91  G-5 154  329.39 48.13 262.55 433.55 316.73  355.03 48.51 266.55 434.85 358.73  136.14 31.49 51.62 170.51 135.09  212.64 5.91 205.99 225.34 209.84  656.38 127.00 477.25 914.70 623.25  0.507 0.110 0.325 0.746 0.5155  R U N 5 - C O N T R O L 0/100, DAY 1  T E S T 0/100 solubilized - N U T R I E N T D A T A (mg/L a s N or P) U N S E T T L E D M I X E D L I Q U O R (B-side)  DATE 11/20 a p  2  11/21  3  11/22 a I  a  4  P 11/23 a I  5  P 11/24 a  p  p  6  11/25 a 11/26 a | 157.47 13.99 14-.86  AVG STDS MIN MAX MEDIAN  175.41 155.66  0.050 0.038 0.000 0.089 0.0605  250.40 18.08 229.47 281.16 249 7 :  7.575 0.518 6.672 8.025 7.757  0.025 0,024 0.000 0.059 0.0225  109.58 12.25 99.27 131.48 105.09  0.079 0.078 0.026 0.232 0.0545  234.94 19.95 209.19 259.59 230.51  6.437 2.445 3,313 10.082 6.411  0.042 0.033 0.002 0.076 0.0455  lost s a m p l e below detection limit (for P 0 4 , N O x , N H 4 ) detection limit = 0 . 0 5 mg/L (for P 0 4 , N O x , N H 4 )  R U N 5 - C O N T R O L 0/100, DAY 1  DATE 11/20 a  2  11/21  P a  3  11/22  P a  4  P 11/23 a  5  P 11/24 a  6  P 11/25 a 11/26 a  T E S T 0/100 solubilized - N U T R I E N T D A T A (mg/L a s N or P) J CONTROL REACTOR FEED, mm N O x P04 TKN solubleTKN NH4 TP solubleTP 7 48 5 450 241,50 41.00 42.08 536.00 0.182 668,00 11.04 305.45 53.03 53.34 0.102 7.750 40.07 679.10 7.53 0.143 4.770 313.15 42.02 49.43 451.45 11.75 0.154 6.040 217.70 53.72 5.58 0.184 5.420 223.45 38.63 42.34 465.10 56.67 0.147 6.840 6 5 . 9 9 5 8 1 . 1 5 10.30 281.25 46.49 47.47 460.15 5.52 0.200 5.690 237.75 626,00 6.18 0.143 7.100 284.75 66.39 59.48 667.45 B.45 0.171 299.05 59.07 61.94 7.110 10.79 0.171 10.850 296.95 71.70 78.39 616.45 45.64 100.65 8.32 0.161 6.970 76.30 41.03 63.38 402.30 17.28 0.571 13.580 179.10 62.88  246.37 68.00 76.30 313.15 261.38  AVG STDS MIN MAX MEDIAN  R U N 5 - C O N T R O L 0/100, DAY 1  DATE 11/20 a P a  2  11/21  3  P 11/22 a  4  P 11/23 a  5  P 11/24 a  6  AVG STDS MIN MAX MEDIAN  P 11/25 a 11/26 a  52.20 11.22 38.63 71.70 51.23  54.65 11.48 42.02 78.39 53.53  521.15 163.62 100.65 679.10 558.58  9.18 3.33 5.52 17.28 8.39  0.194 0.121 0.102 0.571 0.166  7.298 2.526 4.770 13.580 6.905  T E S T 0/100 solubilized - N U T R I E N T D A T A (mg/L a s N or P) O N I K O L A T A D R E / CTOR.6/10 3 TKN solubleTKN NOx NH4 TP P04 solubleTP 154.85 763.80 182.02 311.55 167.6? 254.64 6.256 174.54 174.80 672.95 284.33 0.229 274.00 154.84 274.17 0.260 166.83 343.55 169.25 154.52 837.25 169.41 680.75 265.46 0.239 155.12 272.85 149.30 262.98 699.40 0.260 151.09 297.80 166.62 148.45 700.75 272.52 313.45 168.86 149.74 0.335 149.64 504.90 266.66 226.60 176.04 156.66 0.390 153.62 650.70 242.31 152.37 0.488 138.98 294.85 162.92 648.75 177.08 155.58 267.30 0.536 150.77 289.65 228.50 496.75 255.92 0.485 146.53 172.20 156.29 543.35 258.62 231.55 173.96 155.97 0.435 154.36 645.70 225.96 0.474 277.90 152.72 143.57 140.62 250.19 36.59 226,60 343.55 283.78  i  169.24 6.70 152.72 177.08 169 33  152.0,3 4.07 143.57 156.66 154.68  653.75 100.12 496.75 837.25 661.83  260.90 15.36 225.96 284.33 264.22  0.366 0.115 0.229 0.536 0.3625  155.34 12.97 138.98 182.02 152.36  G-6 ISS  TEST TP solubleTP 247.45 78.60 234.45 122.44 250.50 75.41 130,43 207.05 253.15 82,09 258.90 141.75 244.20 95.55 263.25 137.44 296.35 101.36 282.70 140.44 137.30 60.15 110.85 89.10  T _ < T A T A D R E A C T 6 R , 0/100 solubil z e d TP P04 TKN solubleTKN NOx solubleTP 310.55 187,35 166.00 747.35 301.05 0.229 0.272 277.65 165.66 165.41 643.80 264.77 266.30 176.01 159.16 620.20 266.36 0.265 181.91 267.84 0.249 295.40 157.63 670.35 609.45 259.67 0.256 262.55 169.56 155.79 262.10 165.69 150.54 569.45 230.67 0.309 166.08 148.66 457.25 255.69 0.255 195.20 160.77 134.19 490.20 215.72 0.378 239.55 239.20 164.81 152.07 421.10 217.46 0.394 149,73 539.15 244,40 0.361 259.95 167.09 0.386 590.70 255.69 297.00 173.57 156.10 237.35 141.20 131.54 520.05 192.12 0.557  NH4 202.79 193.80 185.30 179.36 173.72 173.73 170.75 169.74 171.06 175.50 190.70 174.46  261.90 31.71 195.20 310.55 262.33  180.08 10.67 169.74 202.79 174.98  152.24 10.63 131.54 166.00 153,93  502.77 153.06 200.40 703.95 539.58  NH4 14.93 32.30 15,04 37,15 15,29 46.55 16.74 56.49 19.49 53.41 19.69 25.18 29.44 15.46 14.93 56.49 22.44  168.31 11.52 141.20 187.35 166.58  103.51 30,33 62,05 145.40 93.14  F E E D , 6/106 solubilized solubleTKN NOx TKN 536.70 79.58 0.293 502.20 130.91 0.237 0.307 541.10 65.14 117,45 465,55 0.162 554,75 71.44 0.218 538.05 120.26 0.173 550.95 64.05 0.234 596.70 0,282 109.43 703.95 66.45 0.379 0.231 637.65 111.71 0.148 200.40 52.69 0.487 205.25 81.53 0.263 0.097 0.148 0.487 0.2355  232.18 55.48 110.85 296.35 248.98  104.56 26.72 60 1 5 141.75 98.46  REACTOR P04 76.22 128.07 73.B0 121.81 84.77 140.12 87.66 145.40 98.62 143.25 62.05 80.34  573.25 93.44 421.10 747.35 580.08  89.22 26.88 52.69 130.91 80.55  247.62 29.37 192.12 301.05 255.69  0,326 0.094 0.229 0.557 0.2905  PRIMARY SLUDGE P04 | TKN NOx | 0.675 3.711 205.46  NH4 28.83  S E T T L E D M I X E D L I Q U O R (Secondary Sludge) NOx | NH4 TP P04 | TKN 285.38 0.960 16.116 165.90 81.17  DAY 1  DATE 12/02 a  TP 37.76  2  p 12/03 a  31.58  3.256  191.66  0.750  31.68  530.40  98.54  1153.31  1.200  17.013  3  P 12/04 a  31.041  3.3751  194.63  0.729  30.77  498.68  128.22  1094.85  0.880  18.669  4  P 12/05 a  27.56  3.131  181.02  0.853  31.00  684.90  108.67  1512.53|  1.110  18.393  5  P 12/06 a  24.75  3.011  153.54  0.818  34.37  360.381  6  P 12/07 a  22.021  2.963  143.45  0.710  27.74  665.63  127.43  1428.98  0.850  19.281  AVG STDS MIN MAX  29.12 5.59  3.241 0.276  30.73 2.31 27.74 34.37  484.31 196.05 165.90  90.67 47.87 0.00  29.30  128.22 108.67  288.36 1512.53  MEDIAN  684.SO 514.54  0.833 0.430 0.000 1.200  14.808 6.758  2.963 3.711 3.1S35  0.756 0.067 0.675  1032.18 460.56  22.02 37.76  178.29 24.57 143.45 205.45  1124.08  0.96  715.051  14.186  P  186.34  0.853 0.7395  30.88  0.000 19.281 17.703  lost s a m p l e below detection limit (for P 0 4 , N O x , N H 4 ) detection limit = 0 . 0 5 mg/L (for P 0 4 , N O x , N H 4 )  R U N 6 - C O N T R O L 35/65,  T E S T 35/65 solubilized - N U T R I E N T D A T A (mg/L a s N or P)  TEST REACTOR FEED, 35/65 solubil z e d  CONTROL REACTOR FEED, SS/SS DAY 1  DATE 12/02 a  2  P 12/03 a  3  P 12/04 a  4  p 12/05 a  5  P 12/06 a  6  p 12/07 a P  AVG STDS MIN MAX MEDIAN  solubleTP TP 314.80 78.65 125.39 314.40 81.92 283,10 130.88 277.40 257.85 82.83 256.60 116.66 351 25 76.53  P04 79.37 131.05 85.14 136.29 90.61 135.67 84.58  TKN solubleTKN 729.40 17.03 734.60 20.45 645.25 17.09 637.40 22.02 574.15 17.99 597.05 26.63 850.80 18.72  329.45 152.05 187.65 339.40 334.00  122.94 69.63  126.62 72.98 95.10 90.65 139.40  921.20 327.25 429.80 814.60 776.50  26.96 15.20  283.16 61.93 152.05 351.25 2S8.75  100.25  105.62 25.67 72.98 139.40 92.88  669.83 172.44 327.25 921.20 687.33  20.57  91.86 89.16 136.58  24.26 69.63 136.58 90.51  23.52 17.91 23.36  3.89 15.20 26.96 19.58  NOx 0.740 0.980 0.700 0.820 0,080  NH4 23.39 27.11 21.15 31.89  1.050 1.010  25.04 31.43 22.31  0.910 0.820 1.070 0.720 0 S10  29.13 22.50 23.52 24.66 32,77  0.818 0.265 0.080 1.070 0.865  26.24 4.11 21.15 32.77 24.85  P04 90.05 133.73 91.84 139.09  TKN solubleTKN 742.80 665 65 68.93  99.74 138.03 96.66 142.26 72.06 107.54  104.12 145.37 95.94 147.32 78.99 111.76  628.85 906.60  46.65 73.83 64.16 65.76  103.04 146.31  105.31 155.69  724.55 507.10 366.35 347.70 656.70 599.05  38.52 68.00 31.23 71.70 46.29 77.49  113.65  116.60 26.22 78.99 155.69 108.54  618.59 154.99 347.70 906.60 638.95  59.32  24.97 72.06 146.31 107.54  285.20 396.70 322.20 219.40 179.00 168.55 297.20 259.70 276.36 64.60 168.55 396.70 284.50  628 65 649.05  15.74 31.23 77.49 65.76  NOx 1.050 1.190 1.200 1.000 1.070 1.150 1.030 0,950  NH4 27.55 72.66 30.15 84.07 41.05 92.41 29,84  0.700 1.040 0.980 1.100  82.23 26.85 72.60 36.10 97.47  1.038 0.133 0.700 1.200 1.045  57.75 28.07 26.85 97.47 56.83  R U N 6 - C O N T R O L 35/65, DAY 1  DATE 12/02 a  2  p 12/03 a  3  p 12/04 a  4  P 12/05 a  5  p 12/06 3  6  AVG STDS MIN MAX MEDIAN  P 12/07 a p  T E S T 35/65 solubilized - N U T R I E N T D A T A (mg/L a s N or P) C" O N T R O L A T A D R E / ^ C T O R , 35/6 5 solubleTKN NOx NH4 TP solubleTP P04 TKN 559,00 259,37 139.1? 1.630 194.53 237.20 169.65 2 6 6 , 1 6 177.77 143.34 6 7 2 . 1 0 1.610 209.93 287.40 280,54 1.480 197.19 240.65 184.68 145.56 558.60 527.70 251.88 1.350 312.49 226.35 196.86 145.48 151 67 568,75 1.390 308.26 204.26 264.57 245.00 153.36 633.25 1.290 350.52 278,80 203.09 265.22 5 5 6 , 8 0 3 08.76 195.74 162.87 285.48 1.450 242.20 157.85 574.05 263.70 1.490 262.92 253.95 212.91 265,73 158.61 1.310 258.95 249.05 200.25 577,10 620.45 1,360 265.45 155.70 375.73 202.31 285,81 149.54 234.00 193.56 566.70 198.11 0.700 338.96 202.97 : 5.8.3? 594 l i 281.31 1.590 339.68 254.20  TP solubleTP 338.20 293.55 129.33 272.85 84.45 283.80 130.79  195 29  251.19 18.18 226.35  12.43 169.05  287.40 247.03  212.91 198,56  151.79 7.27 139.17 162.87 152.52  T E E T A T A D R E A C T O R , 35/65 SOIUDI z e d NOx TP solubleTP P04 TKN solubleTKN 265.50 196,62 152,78 621.60 2?9.96 1.226 236.70 188.51 152.00 568.70 1.430 271.64 246.90 195.59 150.86 584.30 288.75 1.310 559.90 246.00 191.69 151.76 286.01 1.260 236.00 191.09 152.69 494.12 280.28 1.210 249.60 182.57 153.57 560.30 279.81 1.110 1.460 244.10 189.50 165.73 558.50 285.44 194,09 555.80 275.54 235.05 158.59 1.540 188,24 157.97 1,500 207.15 485.25 271.02 229.65 194.99 157.19 498.40 289.37 1.220 1 5 3 . 1 0 1.460 224.80 198.11 510.40 287.69 154.37 184.10 188.01 399.25 281.31 1.290  584.05  264.00  1.388  288.16  233.96  39.86 527.70 672.10 571.40  23.42 198.11 285.81 265.47  0.245 0.700 1.630 1.42  62.42 194.53 375.73 308.51  21.29 184.10 265,50 237.35  G-7  \S<o  191.58 4.48 182.57 198.11 191.39  155.05 4.21 150.86 165.73 153.34  533.13 58,64 399.25 621.60 557.65  281,40  1.334  6.31 271,02 289.37 280.79  0.138 1.110 1,540 1,3  NH4 300.59 321,84 315.00 380.61 349.33 304.14 283.05 242.06 310.84 338.61 324,31 292.14 313.54 34.84 242.06 380,61 312.92  APPENDIX H: TOC DATA  H- 1 \5?  RUN 1 - CONTROL 100/0, TEST 100/.0 - TOC DATA (mg/L) Test Control Test Control ATAD ATAD Feed Feed DATE DAY 615 615 591 591 9/11 a 1 622 622 570 570 P 9/12 a 2 3  P 9/13 a  4  P 9/14 a  5  P 9/15 a  6  P 9/16 a  538 555  538 555  588 550  588 550  603 563  603 563  678 714  678 714  570 24 538 603 566  570 24 538 603 566  11928 59 550 714 619  628 59 550 714 619  P AVG STDS MIN MAX MEDIAN NOTE :  One set of samples was used for both the control and test data.  RUN 2 - CONTROL 100/0, TEST 65/35 - TOC DATA (mg/L) Test Test Control Control ATAD ATAD Feed Feed DATE DAY 1042 777 691 795 9/27 a 1 1021 771 682 749 P 2 9/28 a 3  P 9/29 a  4  P 9/30 a  5  P 10/01 a  6  P 10/02 a  623 829  707 834  680 759  1008 984  708 685  802 886  681 684  939 975  731 75 623 829 728  796 61 707 886 789  696 31 680 759 683  995 37 939 1042 996  P AVG STDS MIN MAX MEDIAN  H-2  ISS  RUN 3 - CONTROL 100/0, TEST 35/65 - TOC DATA (mg/L) Test Control Test Control Feed Feed ATAD ATAD DAY DATE 1 10/12 a 2  P 10/13 a  3  P 10/14 a  4  P 10/15 a  5 6  P 10/16 a P 10/17 a  524 570  778 760  590 560  938 966  484 564  1076 1184  530 525  865 898  594 580  820 864  608 506  975 1013  553 41 484 594 544  914 175 760 1184 821  553 40 506 608 528  943 54 865 1013 918  P AVG STDS MIN MAX MEDIAN  RUN 4 - CONTROL 100/0, TEST 0/100 - TOC DATA (mg/L) Test Test Control Control Feed Feed ATAD ATAD DAY DATE 10/27 a 547 1352 543 1531 1 542 565 1185 1335 P 2 10/28 a 3  P 10/29 a  4  P 10/30 a  5  P 10/31 a  6  P 11/01 a  602 659  741 720  507 542  1559 1454  656 613  1023 943  584 542  1252 1229  520 233 0 659 608  994 248 720 1352 983  543 24 507 584 542  1393 142 1229 1559 1395  P AVG STDS MIN MAX MEDIAN  H-3 159  RUN 5 - CONTROL 0/100, TEST 0/100 solubilized- TOC DATA (mg/L) Test Control Test Control ATAD ATAD DATE Feed Feed DAY 502 472 49 320 1 11/20 a 522 468 52 568 P 512 426 50 298 2 11/21 a 422 44 517 508 P 478 ' 465 11/22 a 45 306 3 572 325 45 519 P 346 496 363 4 11/23 a 45 41 527 562 352 P 377 273 687 11/24 a 43 5 42 381 500 573 P 45 231 608 363 11/25 a 6 357 46 342 455 11/26 a AVG STDS MIN MAX MEDIAN  46 3 41 52 45  396 120 231 568 344  537 66 455 687 517  400 55 325 502 379  RUN 6 - CONTROL 35/65, TEST 35/65 solubilized - TOC DATA (mg/L) Control Test Control Test DAY DATE Feed Feed ATAD ATAD 10/02 a 792 1 60 186 761 112 417 1124 828 P 2 56 202 12/03 a 1685 848 94 319 1052 746 P 3 12/04 a 61 186 1205 1960 102 300 1108 887 P 64 4 12/05 a 200 1690 1105 114 338 1687 894 P 5 12/06 a 50 163 1693 1023 79 430 1071 1055 P 6 12/07 a 60 241 888 961 100 438 1052 1246 P AVG STDS MIN MAX MEDIAN  79 24 50 114 72  285 103 163 438 271  1270 332 792 1693 1165  H-4 I60  1010 322 746 1960 928  APPENDIX J: FORMULAS & SAMPLE CALCULATIONS  J-1 \(a\  T O T A L SOLIDS  T  S  =  (™™  mg  s ie)-(?n™ J  dried  amp  V  °  l  u  m  d  e  sample  N o t e  .  10  000mg/L=10g/L=l%TS  L  SLUDGE VOLUMES FOR FEED RATIOS  L L L L  0  x  2  w  = volume of sludge remainingfromprevious day gJL = consistency of sludge remaining = volume of primary sludge g / L = consistency of primary sludge = volume of secondary sludge g /L = consistency of secondary sludge = volume of distilled water 2  control feed tank:  1  o  test feed tank: ^y^jL)  =g  o  (L^igJL)  =g  x  -  (mix ratio, ie. ||)  = g required 2  = L required  2  2  g IL 2  *f 8 tes, IL  >  8 con»oi IL  g gl g +  +  0  2  = totai L  j T  required  8 control ILl  ~ -total- ( o l  L  + L  i  + L  i)  =  K required  Note: if g/L^ < g/L „ then g/L^, was used and L was calculated for control feed tank. aM  ib  w  J-2  T O T A L SOLIDS DESTRUCTION  f^~  % destruction =  TS  ATAD  TS  X  L  0  Q  %  TS  feed  where for da : avg TS yi  feed  ^ATAD  =  TS . + TS, . + TS . " ^ ^ f  f  f  ^ATAD,  QUATTRO PRO EQUATIONS  _ Ex,. AVG = x = n  STDS = o =  MEDIAN  E(x-s,) M  n-l  = the middle value for an odd number of values = the average of the two middle values for an even number of values  J-3  APPENDIX K: STATISTICS TABLES  K- 1 14*  T-Test Results for ATAD Temperature (5% significance)  t-Test: Paired Two-Sample for Means RUN 1 T E M P E R A T U R E Mean Variance Observations Pearson Correlation Pooled Variance Hypothesized Mean Difference df t P(T<=t) one-tail t Critical one-tail P(T<=t) two-tail t Critical two-tail  CONTROL 49.075 0.7529545 12 0.992283 0.88375 0 11 47.228936 2.354E-14 1.7958848 4.696E-14 2.2009852  t-Test: Paired Two-Sample for Means RUN 2 T E M P E R A T U R E CONTROL 48.791667 Mean Variance 1.497197 12 Observations Pearson Correlation 0.7568857 0.8644697 Pooled Variance Hypothesized Mean Difference 0 11 df 16.089631 t P(T<=t) one-tail 2.718E-09 t Critical one-tail 1.7958848 5.436E-09 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means CONTROL RUN 3 T E M P E R A T U R E Mean 45.008333 1.4935606 Variance 12 Observations 0.8349524 Pearson Correlation 0.9726515 Pooled Variance Hypothesized Mean Difference 0 11 df t 5.2598108 0.0001342 P(T<=t) one-tail t Critical one-tail 1.7958848 P(T<=t) two-tail 0.0002685 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means RUN 4 T E M P E R A T U R E CONTROL Mean 44.158333 0.7244697 Variance Observations 12 Pearson Correlation 0.9102993 0.7705924 Pooled Variance 0 Hypothesized Mean Difference df 11 t 19.220348 P(T<=t) one-tail 4.092E-10 t Critical one-tail 1.7958848 P(T<=t) two-tail 8.184E-10 t Critical two-tail 2.2009852  TEST 46.6 1.0145455 12  t-Test: Paired Two-Sample for Means RUN 5 T E M P E R A T U R E CONTROL Mean 44.166667 Variance 1.1787879 Observations 12 Pearson Correlation 0.972932 Pooled Variance 1.764053 Hypothesized Mean Difference 0 df 11 t 6.7015787 P(T<=t) one-tail 1.684E-05 t Critical one-tail 1.7958848 P(T<=t) two-tail 3.369E-05 t Critical two-tail 2.2009852  TEST 44.541667 0.2317424 12  t-Test: Paired Two-Sample for Means RUN 6 T E M P E R A T U R E CONTROL Mean 44.1 Variance 0.5363636 Observations 12 Pearson Correlation 0.7830791 Pooled Variance 0.4582955 Hypothesized Mean Difference 0 df 11 t 10.032358 P(T<=t) one-tail 3.579E-07 t Critical one-tail 1.7958848 P(T<=t) two-tail 7.158E-07 t Critical two-tail 2.2009852  TEST 43.858333 0.4517424 12  Note: if |t| > t critical, a significant difference exists between means  K-2  TEST 42.076667 0.8167152 12  TEST 43.125 2.3493182 12  TEST 42.775 0.3802273 12  T-Test Results for ATAD ORP (5% significance)  t-Test: Paired Two-Sample for Means RUN 1 O R P CONTROL -242.66667 Mean 14.606061 Variance 12 Observations Pearson Correlation 0.6516014 29.132576 Pooled Variance Hypothesized Mean Difference 0 11 df t 52.340668 P(T<=t) one-tail 7.661 E-15 1.7958848 t Critical one-tail 1.521E-14 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means CONTROL RUN 2 ORP Mean -254.75 Variance 35.295455 12 Observations Pearson Correlation 0.2708793 Pooled Variance 38.840909 Hypothesized Mean Difference 0 11 df 54.73204 t P(T<=t) one-tail 4.663E-15 t Critical one-tail 1.7958848 9.326E-15 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means CONTROL TEST RUN 4 ORP Mean -274.41667 -421.33333 126.44697 8.2424242 Variance 12 12 Observations Pearson Correlation 0.2346629 67.344697 Pooled Variance Hypothesized Mean Difference 0 11 df t 46.548846 2.753E-14 P(T<=t) one-tail 1.7958848 t Critical one-tail 5.507E-14 P(T<=t) two-tail t Critical two-tail 2.2009852  TEST -318.75 43.659091 12  t-Test: Paired Two-Sample for Means CONTROL TEST RUN 5 ORP -330.41667 -282.83333 Mean Variance 694.08333 15638.515 12 Observations 12 Pearson Correlation 0.2723413 8166.2992 Pooled Variance Hypothesized Mean Difference 0 11 df t -1.3670736 P(T<=t) one-tail 0.0994445 t Critical one-tail 1.7958848 P(T<=t) two-tail 0.198889 t Critical two-tail 2.2009852  TEST -373.75 42.386364 12  t-Test: Paired Two-Sample for Means CONTROL RUN 6 ORP -354.41667 Mean Variance 134.08333 Observations 12 Pearson Correlation 0.4730378 Pooled Variance 90.962121 Hypothesized Mean Difference 0 df 11 t 26.505586 P(T<=t) one-tail 1.28E-11 t Critical one-tail 1.7958848 P(T<=t) two-tail 2.559E-11 t Critical two-tail 2.2009852  t-Test: Paired Two-Sample for Means CONTROL TEST R U N 3 ORP Mean -261.91667 -393.33333 139.7197 21.69697 Variance 12 12 Observations 0.6098141 Pearson Correlation Pooled Variance 80.708333 Hypothesized Mean Difference 0 df 11 t 46.888408 2.542E-14 P(T<=t) one-tail 1.7958848 t Critical one-tail 5.085E-14 P(T<=t) two-tail 2.2009852 t Critical two-tail  Note: if |t| > t critical, a significant difference exists between means  K-3  TEST -433.25 47.840909 12  T-Test Results for VFA Levels in Sludge Feed (5% significance)  t-Test: Paired Two-Sample for Means CONTROL RUN 1 FEED TOTAL V F A 290.90647 Mean 651.33341 Variance 12 Observations 0.7564154 Pearson Correlation 673.16228 Pooled Variance 0 Hypothesized Mean Difference 11 df 3.2152984 t 0.0041138 P(T<=t) one-tail 1.7958848 t Critical one-tail 0.0082276 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means CONTROL RUN 2 FEED TOTAL V F A 212.71006 Mean 761.31298 Variance 12 Observations 0.6128691 Pearson Correlation 3612.3576 Pooled Variance 0 Hypothesized Mean Difference 11 df -2.9161821 t 0.0070165 P(T<=t) one-tail 1.7958848 t Critical one-tail 0.014033 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means CONTROL RUN 3 F E E D T O T A L V F A 169.48767 Mean 2762.1445 Variance 12 Observations 0.4631107 Pearson Correlation 2360.0008 Pooled Variance 0 Hypothesized Mean Difference 11 df 2.447162 t 0.0162043 P(T<=t) one-tail 1.7958848 t Critical one-tail 0.0324085 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means CONTROL RUN 4 F E E D T O T A L V F A 181.76775 Mean 1561.5804 Variance 12 Observations 0.2295492 Pearson Correlation 865.13784 Pooled Variance 0 Hypothesized Mean Difference 11 df 15.607317 t 3.75E-09 P(T<=t) one-tail 1.7958848 t Critical one-tail 7.499E-09 P(T<=t) two-tail 2.2009852 t Critical two-tail  TEST 274.08419 694.99115 12  t-Test: Paired Two-Sample for Means CONTROL RUN 5 F E E D T O T A L V F A 3.0578333 Mean 1.6109287 Variance 12 Observations -0.4810779 Pearson Correlation 3034.7928 Pooled Variance 0 Hypothesized Mean Difference 11 df -6.0740338 t 4.014E-05 P(T<=t) one-tail 1.7958848 t Critical one-tail 8.029E-05 P(T<=t) two-tail 2.2009852 t Critical two-tail  TEST 269.2175 6463.4023 12  t-Test: Paired Two-Sample for Means CONTROL RUN 6 F E E D T O T A L V F A 23.195639 Mean 88.046499 Variance 12 Observations 0.5915625 Pearson Correlation 2530.3438 Pooled Variance 0 Hypothesized Mean Difference 11 df -4.8802527 t 0.0002433 P(T<=t) one-tail 1.7958848 t Critical one-tail 0.0004867 P(T<=t) two-tail 2.2009852 t Critical two-tail  TEST 133.70211 1957.857 12  NOTE: if |t| > t critical, a significant difference exists between means  K-4 16?  TEST 7.5846389 168.69527 12  TEST 140.72901 6067.9746 12  TEST 115.33892 4972.6411 12  T-Test Results for VFA Levels in ATAD (5% significance)  t-Test: Paired Two-Sample for Means RUN 1 A T A D T O T A L V F A Mean Variance Observations Pearson Correlation Pooled Variance Hypothesized Mean Difference df t P(T<=t) one-tail t Critical one-tail P(T<=t) two-tail t Critical two-tail  CONTROL 148.05689 232.6638 12 0.1244804 210.9229 0 11 -2.7890795 0.0088078 1.7958848 0.0176155 2.2009852  t-Test: Paired Two-Sample for Means CONTROL RUN 2 A T A D T O T A L V F A 250.73333 Mean' 979.91615 Variance 12 Observations 0.2840417 Pearson Correlation 1815.7645 Pooled Variance 0 Hypothesized Mean Difference 11 df t -20.893141 1.671E-10 P(T<=t) one-tail 1.7958848 t Critical one-tail 3.343E-10 P(T<=t) two-tail 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means RUN 3 A T A D T O T A L V F A CONTROL 205.05625 Mean 523.51304 Variance 12 Observations Pearson Correlation -0.0101268 Pooled Variance 1455.5785 Hypothesized Mean Difference 0 11 df t -14.669602 P(T<=t) one-tail 7.202E-09 1.7958848 t Critical one-tail P(T<=t) two-tail 1.44E-08 2.2009852 t Critical two-tail  t-Test: Paired Two-Sample for Means RUN 4 A T A D T O T A L V F A CONTROL Mean 203.48983 1017.215 Variance 12 Observations Pearson Correlation 0.4739458 Pooled Variance 7253.3465 0 Hypothesized Mean Difference 11 df t -20.033246 P(T<=t) one-tail 2.625E-10 1.7958848 t Critical one-tail P(T<=t) two-tail 5.25E-10 2.2009852 t Critical two-tail  TEST 163.53594 189.182 12  t-Test: Paired Two-Sample for Means RUN 5 A T A D T O T A L V F A CONTROL Mean 30.503889 Variance 987.90338 12 Observations Pearson Correlation 0.4812847 Pooled Variance 495.90561 Hypothesized Mean Difference 0 df 11 t 2.9905515 P(T<=t) one-tail 0.0061428 t Critical one-tail 1.7958848 P(T<=t) two-tail 0.0122856 t Critical two-tail 2.2009852  TEST 565.04675 2651.6129 12  t-Test: Paired Two-Sample.for Means RUN 6 A T A D T O T A L V F A CONTROL Mean 391.91654 Variance 7320.7628 12 Observations Pearson Correlation 0.3553911 14294.624 Pooled Variance Hypothesized Mean Difference 0 df 11 t -2.1285699 P(T<=t) one-tail 0.0283601 t Critical one-tail 1.7958848 P(T<=t) two-tail 0.0567202 t Critical two-tail 2.2009852  TEST 434.42964 2387.644 12  NOTE: if |t| > t critical, a significant difference exists between means  K-5  TEST 809.90064 13489.478 12  TEST 4.1485 3.9078355 12  TEST 478.20478 21268.485 12  

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