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The effect of primary and secondary sludge mix ratios on VFA production in thermophilic aerobic digestion.. 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. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. ; Department of -..<2.-l\J\i- <s= *4.<^• ^&<&g_i G>- The University of British Columbia Vancouver, Canada Date <Z>CZ-T 2 - 4 / 5 fo DE-6 (2788) 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 as first stage 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). i i 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 large fluctuations in 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. i i i TABLE OF CONTENTS ABSTRACT .< ii LIST OF TABLES vi LIST OF FIGURES vii LIST OF APPENDICES viii ACKNOWLEDGEMENTS . . . ix 1.0 INTRODUCTION 1 1.2 Project Objectives 2 2.0 LITERATURE REVIEW 3 2.1 Thermophilic Aerobic Digestion 3 2.1.1 Process Description 4 2.1.2 Facilities in North America 6 2.2 Volatile Fatty Acids 8 2.3 Volatile Fatty Acids in Therophilic Aerobic Digestion 10 2.3.1 Detection 10 2.3.2 Theory of Production 11 2.3.3. Effects of Operating Conditions 13 2.3.3.1 Temperature 14 2.3.3.2 Aeration 16 2.3.3.3 Retention Time 18 2.3.3.4 Feed Sludge 20 2.3.3.5 Pre-Solubilization 22 3.0 METHODS AND MATERIALS 23 3.1 Experimental Set-Up 23 3.1.1 Sludge Source 25 3.1.2 ATAD Reactors 28 3.1.3 Retention Time 28 3.1.4 Mixing and Aeration 29 3.2 Monitoring Variables 31 3.2.1 Temperature 31 3.2.2 Turborator™ Speed 31 3.2.3 ORP 32 3.2.4 Dissolved Oxygen 32 3.2.5 Airflow 33 3.2.6 Air Composition 35 3.2.7 pH 35 3.2.8 Total Solids 35 3.3 Experimental Variables 36 3.3.1 Volatile Fatty Acids 36 i v 3.3.2 Nitrogen and Phosphorus 38 3.3.3 Total Organic Carbon 39 3.4 Sampling Points 40 3.5 Interpretation of Results 41 4.0 RESULTS AND DISCUSSION 42 4.1 Experimental Set-up 42 4.2 Operating Conditions 43 4.2.1 Source Sludge 43 4.2.2 Temperature 48 4.2.3 Turborator™ Speed 53 4.2.4 ORP 55 4.2.5 Dissolved Oxygen 61 4.2.6 Airflow 61 4.2.7 Air Composition 63 4.2.8 pH 65 4.2.9 Feed Total Solids 68 4.3 Total Solids Destruction 70 4.4 VFA Production - Mixed Sludge Ratio Runs 73 4.4.1 Feed Streams 73 4.4.2 AT AD VFA Production 75 4.5 VFA Production - Pre-solubilization Runs 80 4.5.1 Feed Streams 80 4.5.2 ATAD VFA Production 83 4.6 VFA Production-Run Inconsistency 86 4.7 VFA Speciation 89 4.8 Nutrients 9 2 4.8.1 Phosphorus 9 2 4.8.2 Nitrogen 9 5 4.9 Total Organic Carbon 9 8 5.0 SUMMARY 1 0 0 5.1 Operating Conditions 1 0 0 5.2 Enhancement of VFA Production 101 5.3 Pre-Solubilization 1 0 2 5.4 Nutrients 1 0 2 5.5 Phosphorus Release Mitigation 103 5.6 Alternative Applications 1°4 6.0 CONCLUSIONS AND RECOMMENDATIONS 105 REFERENCES 1 0 7 APPENDICES : 1 1 3 v LIST OF TABLES TABLE 2.1: VOLATILE FATTY ACID SPECIES 8 TABLE 2.2: TYPICAL TAD OPERATING TEMPERATURES 16 TABLE 3.1: EXPERIMENTAL DESIGN 25 TABLE 4.1: EXPERIMENTAL TIMETABLE 42 TABLE 4.2: CHARACTERISTICS OF SOURCE SLUDGE 44 TABLE 4.3: AVERAGE ATAD TEMPERATURE 52 TABLE 4.4: AVERAGED ATAD ORP 59 TABLE 4.5: AVERAGE AIRFLOWS 62 TABLE 4.6: AVERAGE ATAD pH 65 TABLE 4.7: AVERAGE FEED TOTAL SOLIDS 69 TABLE 4.8: TOTAL SOLIDS DESTRUCTION EFFICIENCY 70 TABLE 4.9: AIRFLOW EFFECTS ON VFA ACCUMULATION 80 TABLE 4.10: VFA SPECIATION IN FEED SLUDGE 91 TABLE 4.11: VFA SPECIATION IN ATAD 91 v i LIST OF FIGURES FIGURE 2.1: Location of ATAD Facilities in North America 7 FIGURE 2.2: Model of Enhanced Biological Phosphorus Removal 9 FIGURE 2.3: Temperature Effect of Changes in Turborator™ Speed 15 FIGURE 3.1: Process Flow Diagram of the UBC Pilot Plant 24 FIGURE 3.2: Process Flow Diagram of Experimental ATAD Set-up 27 FIGURE 3.3: Air Flow Meter Set-up 30 FIGURE 3.4: Air Flow Calibration Curves 34 FIGURE 4.1: Source Sludge TP 46 FIGURE 4.2: Source Sludge P0 4 46 FIGURE 4.3: Source Sludge NH 4 47 FIGURE 4.4: Source Sludge VFA 47 FIGURE 4.5: ATAD Temperature Profile, Run 1 . , 49 FIGURE 4.6: ATAD Temperature Profile, Run 2 49 FIGURE 4.7: ATAD Temperature Profile, Run 3 50 FIGURE 4.8: ATAD Temperature Profile, Run 4 50 FIGURE 4.9: ATAD Temperature Profile, Run 5 51 FIGURE 4.10: ATAD Temperature Profile, Run 6 51 FIGURE 4.11: Turborator™ Speed 54 FIGURE 4.12: ATAD ORP Profile, Run 1 56 FIGURE 4.13: ATAD ORP Profile, Run 2 56 FIGURE 4.14: ATAD ORP Profile, Run 3 57 FIGURE 4.15: ATAD ORP Profile, Run 4 57 FIGURE 4.16: ATAD ORP Profile, Run 5 58 FIGURE 4.17: ATAD ORP Profile, Run 6 58 FIGURE 4.18: Effect of Increased Additions of Secondary Sludge on ORP 60 FIGURE 4.19: Shark Tooth Pattern of ORP in Response to Substrate Addition in ATAD 60 FIGURE 4.20: ATAD Air Composition 64 FIGURE 4.21: pH Instability with Pre-solubilization of Feed Sludge 67 FIGURE 4.22: Total Solids Feed Variability 68 FIGURE 4.23: VFA in Feed, Runs 1 to 4 74 FIGURE 4.24: Net VFA Production in ATAD, Runs 1 to 4 76 FIGURE 4.25: ATAD VFA Accumulation as a result of Mixed Sludge Feed 78 FIGURE 4.26: VFA Feed Variability, Runs 5 & 6 82 FIGURE 4.27: Net VFA Production, Runs 5 & 6 84 FIGURE 4.28: ATAD VFA Accumulation as a Result of Pre-solubilization 85 FIGURE 4.29: Run Inconsistency with 100% Secondary Sludge 87 FIGURE 4.30: Run Inconsistency with 35/65 Mix Sludge Ratio 87 FIGURE 4.31: Fate of Ortho-Phosphate 94 FIGURE 4.32: Solubilization of Phosphorus, TP 94 FIGURE 4.33: Fate of Nitrogen, Ammonia 97 FIGURE 4.34: Solubilization of Nitrogen, TKN 97 FIGURE 4.35: Averaged TOC 99 FIGURE Bl : UBC Pilot Plant Facility B - 2 FIGURE B2: Raw Sewage Storage Tanks B - 2 FIGURE B3: Sludge Feed Tanks for ATAD Reactors with mixers B - 3 FIGURE B4: ATAD Reactors with Turborator™ Mixing/Aeration Device B - 4 FIGURE B5: ATAD Reactor Lid B - 5 v i i 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 v i i i 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 to finally finish and 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. i x 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 pathwayŝ 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, pre- solubilization 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 micro- organisms 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 reduced from months 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 the first three, 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 3, C2FL,, etc, attached to a carboxyl group, -COOH (Sharp, 1990). The lower 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 Compound Structure acetic acid CH3COOH propionic acid CH3CFLCOOH iso-butyric acid (CH3)2CHCOOH butyric acid CH3(CH2)2COOH valeric acid CH3(CH2)3COOH iso-valeric (CH3)2CHCH2COOH 2-methylbutyric CH 3 CH 2 CH 3CHCOOH 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 V / bacteria available carbon substrates aerobic zone bk>P bacteria FIGURE 2.2: Model of Enhanced Biological Phosphorus Removal (taken from Chu, 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 side- stream 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 stems from both positive findings and 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 increased from 2470 (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 in final TAD effluent. 2.3.2 Theory of Production Isolating cultures in bench scale studies, Mason & Hamer were one of the first groups 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 collected from a 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/L from April 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 -50°C 5 0 - 6 5 ° C (U.S.EPA, 1990) 5 0 - 5 5 ° C 55 -70°C (Kelly, 1991) 6 0 - 6 8 ° 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 the first to 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 the first reactor. Switching to 2 single stage systems in parallel, to provide a control reactor through experimentation, air flow rates 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 increased from <10 mg/L to 724 mg/L in the first stage, 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 the first 36 hours, then gradually disappear. (Mason et al., 1987b; Bomio et al., 1989). Although the actual time frame of 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 the first stage 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 VFA production using their pure oxygen system as described above. Although results indicate a decrease in net VFA production with a decrease in retention time from 24 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 to VFA 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 smaller fluctuations, 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 in fluctuating and 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). CHL4O04N0.2 + a(02) (CHL8O0,4^0_23} + c (COJ + d (H20) + e (NH*) +f(CJT2n+1COOH) 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 released from secondary 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). Effluent from the ATAD process in Salmon Arm, BC where primary and secondary sludge are co- thickened 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 additional findings to 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 sewage from on-campus housing and residences. To achieve adequate solids loading to the process, sewage is pumped twice daily from a 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 range from 100% 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 -o C M O o u CO O CO c co E d) c CD CO CO c fc o o ' C ' C (]} CD Q . Q . C 0 CO CO -Q CO .Q l - T - CM CM CD o ig-a ^ CO O ) eg <u co ~ CD c "co T3 FIGURE 3.1: Process Flow Diagram of the UBC Pilot Plant 24 TABLE 3.1: EXPERIMENTAL DESIGN Run Primary/Secondary Sludge Ratio (based on TS) Test Reactor Control Reactor Timing (minimum) 1 100/0 100/0 2 SRT acclimitize to 65/35 2SRT 2 65/35 100/0 2 SRT acclimitize to 35/65 2 SRT 3 35/65 100/0 2 SRT acclimitize to 0/100 2 SRT 4 0/100 100/0 2 SRT acclimitize to pre-solubilization acclimitize to 0/100 2 SRT 5 0/100 pre-solubilized 0/100 2 SRT acclimitize to 35/65 & pre- solubilization acclimitize to 35/65 2 SRT 6 35/65 pre-solubilized 35/65 2 SRT 3.1.1 Sludge Source Primary sludge was generated from a 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 pumped from the 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 wasted from the 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 and free water 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 CONTROL SIDE TEST SIDE -> to waste bucket sample 7 24 LJ/day sample 8 24 U/day thickener ATAD Reactors 1 L/hr t X feed tanks > < sample 4 sample 5 1 L/hr X J thickener primary sludge sample > ^ > L 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 sludge from the 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 daily from 60 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 were filled with 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. Air flow was 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 the first 4 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 air flow devices, 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 r J w TT Control Turborator Test 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 vented from the 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 Ag- Cl. 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, flows were 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 air flow meters, 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 absolute flow rates can not be assured, the relative difference should be zero. On the other hand, flow rates from Runs 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 -] 1 1 1 1 1 i 1 1 1 1 1 1 10 20 30 40 50 60 70 Meter Reading Model 022-13 300 0 -I 1 1 1 1 1 i 1 1 1 1 1 1 1.0 20 30 40 50 60 70 Meter Reading FIGURE 3.4: Air Flow Calibration Curves (adapted from Cole-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 a flow through gas sampling vial, fitted with an adaptor for the exhaust gas outlet, a syringe was used to purge and fill the sample chamber. The tube was then sealed and removed from the 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 removed from each 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) and frozen for 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%H3P04 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 acid from the 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 (P04), nitrates (NOJ, and ammonia (NH4) were also prepared on-site. 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 2S0 4. Again, all samples were 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 were frozen to be prepared in the lab. For soluble TP and TKN, sludge samples were additionally centrifuged, filtered and acidified to pH<2 using sulphuric acid before freezing, 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 AE 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 and filtered, 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 and frozen on-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 taken from 6 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 directly from the process during wasting, sample 3 A from A-side and sample 3B from B-side. Feed sludge samples were removed from the feed tanks from a valve located on the tank wall approximately 2 cm from the bottom. Feed tank contents were continually stirred and the valve was flushed with 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 removed from the transfer line to the feed tanks. ATAD samples were taken from the 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 (T- C) 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 averaged first before 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 retention time cycles 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 sub- sections. 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 sampled from the 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, evident. The variability of sewage sludge is TABLE 4.2: CHARACTERISTICS OF SOURCE SLUDGE Parameter Primal avg ry Sludge range Mix avg ed Liquor range Seconda avg iry Sludge 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 4 A 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 introduced from side 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, dropping from >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 contributions from the mixed liquor from A 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 4 5 6 Run FIGURE 4.1: Source Sludge TP 46 40 1 2 3 4 5 6 Run FIGURE 4.3: Source Sludge NH 4 300 1 2 3 4 5 6 Run 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 temperature from midnight 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 40 rpm increase from 925 to 935 Control ATAD 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 O CD i _ 3 -t—< CO i _ CD Q. E CD 52 50 48 46 44 42 40 Control ATAD Test ATAD drop in control mixer speed 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 29th when trailer heat was turned on. 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, pre- solubilization 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 obvious from the 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 the frame, 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 14th is clearly registered as a temperature increase in Run 3 (see Figure 4.7). Similarly, one of the two periods of low speed occurred on December 5th in the control reactor and is registered as a temperature decrease unmatched by the test reactor in Run 6 (see Figure 4.10). The temperature decrease on December 4th in Run 6, paralleled more closely by the test reactor appears to have been caused by another variable. As Turborator™ speeds were averaged for a 24 hour period, not all fluctuations are recorded. 970 C avg = 929 rpm T avg = 934 rpm 950 |930 910 increase in speed setting (min 701 rpm) 890 09/03 09/17 10/01 10/15 10/29 11/12 11/26 Date (mm/dd) — Control Reactor—Test Reactor FIGURE 4.11: Turborator™ Speed 54 4.2.4 ORP The redox potential of the ATAD reactors was also monitored on-line. The readings from the 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 ^ - 1 0 0 o | -200 j^-300 § -400 -500 avg airflow 48 ml/min Control ATAD Test ATAD September 11th to 16th FIGURE 4.12: ATAD ORP Profile, Run 1 0 -500 avg airflow 27 ml/min Test ATAD September 27th to October 2nd FIGURE 4.13: ATAD ORP Profile, Run 2 56 0 £ -100 -500 avg airflow 41 ml/min October 12th to 17th FIGURE 4.14: ATAD ORP Profile, Run 3 0 -w-100 avg airflow 51 ml/min 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 Control (mV) Test (mV) Difference (primary/secondary) avg std dev avg 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 j in 58 6 35/65 solubilized -354 15 -433 9 79 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 - « > ~ - 3 5 0 Q_ rr O CD CD 2 -400 - CD > CO /ten > < 0 2 R = = 0.96 i 0 25 50 75 10 % secondary sludge FIGURE 4.18: Effect of Increased Additions of Secondary Sludge on ORP b) ORP Variations, Sides A and B -320 r 1 fe -410 o -420 Depression of signal . v W V l 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 Air flow rates 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 non- solubilized 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 Control Test (primary/secondary) PH 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 7.8 (feed 6.5) (feed 9.7) 6 35/65 solubilized 6.9 7.4 (feed 6.4) (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 C0 2 increases 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 pre- solubilization 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 pre- solubilization 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 5 6 Day 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. tL 0 Average Difference -0.29 .....L.i.1,.11 -iJilLiJi., ,li dm i. i| >||i i|f ii |i|.< i 'H|I iiiiiiiiiiiiiiiiiiiiiiiiiinmiiiiiuiiiiHiiiiiiiiiiniiiiiiiiiiiiiii miimiiinimmiiiiiiiiiiiMiiiiiniiniiiiimniriMMMH! J iiiiiiiiiiniuiii llliiliiuiiiiiiiiiHiiiimiiiniiiiiiiiiiiiiiiiiiimminmiiimnim iinillliiiliiitiiiiimnniininmi1 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 Control Test (primary/secondary) (%) (%) 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 VFA 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 range from a 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 pre- solubilization 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 Control Test (primary/secondary) (%) (%) 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 the first reactor, 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 the first reactor. 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 efficiency from 12 % 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 pre- solubilization 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 the first 4 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 ranged from a 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 dropped from a high of 274 mg/L with 0% secondary sludge, to 269 mg/L when 35% was added, to 134 mg/L with 65%, and finally to 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 T _l 400 - 15) E 300 < 200 I > 100 - 0 all njns100/0 4 D A Y - 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 both figures to highlight the differences. 75 1000 _ , 750 - 2 5 0 1——^— • 1 •— • r 1 2 3 4 5 6 D A Y - Run 1 Run 2 •- Run 3 R u n 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 the first 4 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 4 DAY • Run 1 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, from the figures presented, 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 adjusted from 65/35 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 Median Total VFA Accumulation (mg/L) 0% Primary Sludge 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 VFA 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 derived from the 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 are from samples 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 of fresh feed 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 in figures). 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 the first 3 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 _j a> 400 z? 200 > 0 -200 -400 (non-solubilized feed) 1 — A A fa— 0/100 35/65 - A ^ Ar- 3 4 DAY Run 5 Run 6 6 (a) Control 3 4 DAY Run 5 - ^ Run 6 6 (b)Test FIGURE 4.27: Net VFA Production, Runs 5 & 6 84 800 600 _ i • o) 400 E 200 < LL > 0 -200 -400 1 TEST - CONTROL pre-solubilized mixed sludge pre-solubilized 100% secondary sludge 4 D A Y 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 VFA 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 | 500 + 250 750 + O) % 500 < 250 + feed ATAD feed ATAD FIGURE 4.29: Run Inconsistency with 100% Secondary Sludge Run 3 Run 6 600 600 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 resulting from pre-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, the fluctuations may 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) iso-butyric (mg/L) butyric (mg/L) % acetate 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% 0/100 3 0 0 0 100 % 0/100 pre-solubilized 108 14 5 14 77% 35/65 19 4 0 0 83 % 35/65 pre-solubilized 82 25 4 5 71% TABLE 4.11: VFA SPECIATION IN ATAD Sludge Mix Ratio (primary/secondary) acetate (mg/L) propionate (mg/L) iso-butyric (mg/L) butyric (mg/L) % acetate 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% 0/100 31 0 0 0 100 % 0/100 pre-solubilized 4 0 0 0 100 % 35/65 365 8 19 0 93% 35/65 pre-solubilized 404 29 45 0 85% 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 (P04) levels in primary sludge feed were consistent through experiments at 5 mg- P/L. Secondary sludge had consistently higher concentrations during the first 4 runs and resulted in a gradual increase in P0 4 levels in the test feed, as the proportion of secondary sludge was increased. In contrast, the 0/100 non-solubilized stream tested in Runs 5 had lower concentrations of P0 4 in both feed and ATAD streams, as compared to the same stream in Run 4, while the 35/65 non-solubilized stream in Run 6 was higher than the in Run 3. Pre-solubilization of feed resulted in increased P0 4 levels in the feed, but levels after digestion were the same. Other than in Run 1, ATAD resulted in an increase in P0 4 concentrations with all feed sludges. Figure 4.31 is a bar graph 92 of average P0 4 concentrations in the feed streams and ATAD reactors, exact values are in Appendix 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. 93 250 200 _ i CL 6)150 E g i o o CL 50 T 0 Feed solubilized ATAD 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 35/65 4- 0/100 LL 35/65 TP soluble TP FIGURE 4.32: Solubilization of Phosphorus, TP 94 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 the first hour of up to 13 mg- N/L, with additional increases, over the next 12 hours, of as much as 60 mg-N/L. Although Knezevic (1993) also recorded increases in NH 4 concentrations with increases in mixing time after NaOH 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, NH 4 accumulated as a result of ATAD treatment. Pre-solubilization resulted in minimal additional increases in NH 4 in the ATAD reactors, as similarly observed for anaerobic digestion of 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 average concentrations calculated for Runs 5 & 6. 96 350 300 ^ 250 |>200 ^ 1 5 0 2 100 50 0 Feed solubilized ATAD 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 I TKN 0/100 35/65 soluble 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 calculated from the 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 1200 _ j 1000 E 800 Feed _n solubilized I " I I " I ATAD 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 recovering from a 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 VFA 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 (MgNH4P04), without chemical addition. 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)2, or other chemicals, might 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 of filamentous blue-green algae in recycle lines to remove N and P (Radway et al., 1994). The algae was introduced, at the point of discharge from a 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. Temperature fluctuations, 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. (1993), Behaviour and Control of Nutrients in the Enhanced Aerobic Digestion Process: Pilot-scale Studies, Environmental Technology, 14(4): 3 01 -318. 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Bruce, A., Colin, F. and Newman, P., Elsevier Applied Science, London, UK, p.20-28. 109 Mason, C.A, Hamer, G., Fleischmann, T. and Lang, C. (1987a), Bioparticulate Solubilization and Biodegradation in Semi-Continuous Aerobic Thermophilic Digestion, Water, Air and Soil Pollution, 34(August):399-407. Mason, C A . , Hamer, G., Fleischmann, T. and Lang, C. (1987b), Aerobic Themophilic Biodegradation of Microbial Cells, Appl. Microbiol. Biotechnol., 25:568-576. Mason, C.A., Haner, A. and Hamer, G. (1992), Aerobic Thermophilic Waste Sludge Treatment, Wat. Sci. Tech., 25(1): 113-118. Mcintosh, K.B. and Oleszkiewicz, JA. (1996), Voaltile Fatty Acid Production in Aerobic Thermophilic Pre-Treatment of Sludge, Proceedings of 4th Environmental Engineering Specialty Conference, CSCE, May 29-June 1, 1996, Edmonton, AB,Canada, p.373-382. Morgan, S.F. and Gunson, H.G. 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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 autothermal thermophilic aerobic digestion ATP aerobic thermophilic pretreatment A V G average BC British Columbia, Canada C control feed/reactor CH 4 or CH4 menthane C0 2 or C02 carbon dioxide DO dissolved oxygen L litre MAX maximum meq/L milliequivalen per litre MTN minimum ML mixed liquor mL millilitre NaOH sodium hydroxide NH 4 or NH4 ammonia nitrogen NO xorNOx nitrate and nitrite nitrogen N 2 orN2 nitrogen (gas) 0 2 or 02 oxygen P0 4 or P04 ortho-phosphate (soluble phosphorus) STDS standard deviation, sample T test feed/reactor TAD thermophilic aerobic digestion TKN total Keidjal nitrogen TOC total organic carbon TP total phosphorus TS total solids UBC University of British Columbia VFA volatile fatty acids VS volatile solids VSS volatile suspended solids Date 09/02 a month/day am (ie. September 2nd) 10/17 p month/day pm (ie. October 17th) Mix Ratio 35/65 35% primary sludge/65% secondary sludge 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. ,-Jr-- c o c o C D c n N N o C M O > T - h- •> KN T - U - o T - k - I T - \T- CM k - CM I CO g |co CO CO CO CO CO CO CO CO I CO I CO I CO o r ^ . c o r - i - T - T r c M c o o o c M O O C O C O C O C O c O c O C O f c O C O C O O ) 0 ) 0 o c o o ) 0 ) c o c o o > c o c o o ) — 1 0 O •* h- CD co w CO O CO CM ,"T iri 10 i r i w f̂r Tfr Tj- T* CO CO co r*- CD CO ICO CO CO CO IO CO CO TJ- I c o I c o I c o jo jo o o d d o o |d |d |d s i f l c o T r i - w c o i - m C O ^ C O ^ - * ^ ' * - * ' * C M C M C M C M C M C M C M C M C M - i Ico T - k t*- co co 0 0)0) m w CM — ,- H CO CO CM CM CM CO CM CM CM CM CM fc |Q) I CD |0) | O) |Q) |0)|0|0)|0|0)|0)|0 < u H IN U j k i_|o> < h- co h- ko o to W CO in in in in in in in w I D S k « CD C O C O i n O J C M C M C O O tocococococococo CO c o c o c o c o c o c d c o F F in m CM o m S CO s f f in in in o co cp co co op o (00)0)0500)0)0 IO CM CO O CO CD k CM CO 00 cp co i n ̂ n i n w l ^ f l i n w ICM co co co I co Ico Ico Ico Ico I CD I CO i i 0 ' c o c o c o ^ r f c o c o c o d o d o d o d o -2 81  -3 19  §"§ S 5 c •3 3 51 .1  49 .0  o o c 3 O O 6. 46 ! 0. 10 1 6. 60  6. 46  d o c •o 15 — != s :°> 0 ° Q . £ CD O n <D C 3 1 8 — in > _3 II E •£ in iS £•". > S si 5 5 flf. a&S | f ^ CO co . co CD 5 i_ « o •Sir £ t £ w tj TD CO CO C i_ CD CO CD C ff O — 3 d ) CJ (D CD CD Q . > Q . 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I I E S si a f. » o S § ^ Q. 2 = C T3 CD O C i- CO CD CD .2 B CD x =6 e ^ Q TO CD 5 [TJ CO Q. 7 u C O ^ s £ g» g eg > E r t (0 _ CM % ra T- i £ C - 4 125 APPENDIX D: AIRFLOW AND AIR COMPOSITION DATA D - 1 126 AIRFLOW DATA (mL/min) - RUNS 1 to 4 Control Test Daily Average DAY DATE am pm am pm Control Test 09/03 41 41 41 41 09/04 32 25 32 25 29 29 09/05 28 34 28 34 31 31 09/06 37 43 37 43 40 40 09/07 34 53 34 53 43 43 09/08 55 55 55 55 55 55 09/09 54 66 54 66 60 60 Run 1 09/10 62 28 62 28 45 45 1 09/11 21 37 21 37 29 29 2 09/12 46 57 46 57 51 51 3 09/13 51 53 51 53 52 52 4 09/14 51 55 51 55 53 53 5 09/15 50 55 50 55 52 52 6 09/16 53 49 53 49 51 51 09/17 49 65 49 65 57 57 09/18 53 61 53 61 57 57 09/19 59 61 59 61 60 60 09/20 53 59 53 59 56 56 09/21 57 57 57 57 57 57 09/23 55 60 55 60 57 57 09/24 60 28 60 28 44 44 09/25 16 30 16 30 23 23 Run 2 09/26 28 25 28 25 27 27 1 09/27 26 26 26 26 26 26 2 09/28 24 28 24 28 26 26 3 09/29 27 32 27 32 29 29 4 09/30 28 26 28 26 27 27 5 10/01 23 27 23 27 25 25 6 10/02 28 26 28 26 27 27 10/03 27 32 27 32 30 30 10/04 29 28 29 28 28 28 10/05 31 32 31 32 32 32 10/06 26 26 26 26 26 26 10/07 26 29 26 29 27 27 10/08 24 37 24 37 30 30 10/09 41 40 41 40 40 40 10/10 34 40 34 40 37 37 Run 3 10/11 34 47 34 47 40 40 1 10/12 34 37 34 37 35 35 2 10/13 34 40 34 40 37 37 3 10/14 37 49 37 49 43 43 4 10/15 37 49 37 49 43 43 5 10/16 43 48 43 48 45 45 6 10/17 43 43 43 43 43 43 10/18 43 38 43 38 40 40 10/19 36 43 36 43 39 39 10/20 38 37 38 37 37 37 10/21 35 34 35 34 34 34 10/22 37 49 37 49 43 43 10/23 65 49 65 49 57 57 10/24 49 55 49 55 52 52 10/25 49 52 49 52 50 50 Run 4 10/26 47 50 47 50 49 49 1 10/27 48 48 48 48 48 48 2 10/28 47 47 47 47 47 47 3 10/29 47 53 47 53 50 50 4 10/30 53 51 53 51 52 52 5 10/31 49 57 49 57 53 53 6 11/01 53 55 53 55 54 54 11/02 54 53 54 53 54 54 11/03 49 57 49 57 53 53 11/04 53 53 53 53 53 53 11/05 49 49 49 49 49 49 11/06 49 47 49 47 48 48 AVG 41 44 41 44 43 43 STDS 12 12 12 12 11 11 MIN 16 25 16 25 23 23 MAX 65 66 65 66 60 60 MEDIAN 43 47 43 47 43 43 D - 2 \2f AIRFLOW DATA (mL/min) - RUNS 5 & 6 Control Test Daily Average DAY DATE am pm am pm Control Test 11/07 47 255 47 255 151 151 11/08 255 314 255 786 285 521 11/09 314 132 397 397 223 397 11/10 113 53 93 89 83 91 11/11 39 56 100 161 47 130 11/12 54 69 172 236 62 204 11/13 64 105 224 224 85 224 11/14 98 95 208 95 96 152 11/15 90 111 95 113 101 104 11/16 110 96 110 96 103 103 11/17 77 56 81 56 66 69 11/18 39 39 41 41 39 41 Run 5 11/19 39 40 41 41 39 41 1 11/20 39 39 41 40 39 41 2 11/21 39 39 39 40 39 39 3 11/22 39 41 41 39 40 40 4 11/23 40 40 39 39 40 39 5 11/24 39 41 39 39 40 39 6 11/25 39 39 39 41 39 40 7 11/26 38 41 39 41 39 40 11/27 39 39 41 44 39 43 11/28 39 39 44 41 39 43 11/29 41 39 38 41 40 39 11/30 39 41 38 44 40 41 Run 6 12/01 39 44 41 40 41 41 1 12/02 39 43 39 39 41 39 2 12/03 44 44 39 41 44 40 3 12/04 44 41 40 41 43 41 4 12/05 39 40 43 41 39 42 5 12/06 39 40 40 42 40 41 6 12/07 40 39 40 40 40 40 AVG 66 69 83 107 68 95 STDS 63 63 84 152 57 111 MIN 38 39 38 39 39 39 MAX 314 314 397 786 285 521 MEDIAN 39 41 41 41 40 41 ALL DATA COMBINED AVG 50 52 55 65 51 60 STDS 39 39 53 91 36 68 MIN 16 25 16 25 23 23 MAX 314 314 397 786 285 521 MEDIAN 40 43 41 43 43 43 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 n o LL 30 20 -I 1 1 ; 1 1 1 1 1 1 11/20 11/24 11/28 12/02 12/06 Date (mm/dd) — Control — Test D - 4 129 R E A C T O R H E A D S P A C E / O F F - G A S AIR ANALYSIS (% composition) DAY D A T E ambient C 0 2 (%) C A T A D T A T A D ambient 0 2 (%) C A T A D T A T A D ambient N2 (%) C A T A D T A T A D ambient C H 4 (%) C A T A D T A T A D Run 4 1 10/27 lab air 0.147 0.535 0.410 20.408 19.819 19.834 79.445 79.646 79.756 n.d. n.d. n.d. 2 10/28 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. 11/02 11/03 lab air n.d. 0.643 0.454 20.438 19.262 19.969 79.562 80.095 79.577 n.d. n.d. n.d. 11/04 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. 11/08 trailer air n.d. 2.676 1.137 20.390 17.704 18.183 79.610 79.620 80.680 n.d. n.d. n.d. 11/09 trailer air n.d. 0.648 1.058 20.258 19.739 19.612 79.742 79.613 79.330 n.d. n.d. n.d. 11/10 lab air n.d. 2.700 0.596 19.934 16.308 19.448 80.066 80.992 79.956 n.d. 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. 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. 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. 11/16 trailer air 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. Run 5 11/19 1 11/20 2 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 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. 11/27 11/28 11/29 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. 11/30 lab air n.d. 1.790 0.457 20.272 17.910 19.519 79.728 80.300 80.024 n.d. n.d. n.d. Run 6 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 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. 6 12/07 lab air n.d. 2.645 0.570 20.134 17.301 19.341 79.866 80.054 80.089 n.d. n.d. n.d. A V G S T D S MIN M A X 0.010 1.574 0.651 20.289 18.353 19.448 79.695 80.069 79.900 0.000 0.000 0.000 0.031 • 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 ] blank cell, no sample taken not detected n.d. 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 ANALYSIS (% composition) D A Y D A T E ambient C 0 2 (%) C A T A D T A T A D ambient 0 2 (%) C A T A D T A T A D ambient N2 (%) C A T A D T A T A D ambient C H 4 (%) C A T A D T A T A D Run 4 1 10/27 lab air 0.147 0.535 0.410 20.408 19.819 19.834 79.445 79.646 79.756 n.d. n.d. n.d. 2 10/28 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. 11/02 11/03 lab air n.d. 0.643 0.454 20.438 19.262 19.969 79.562 80.095 79.577 n.d. n.d. n.d. 11/04 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. 11/08 trailer air n.d. 2.676 1.137 20.390 17.704 18.183 79.610 79.620 80.680 n.d. n.d. n.d. 11/09 trailer air n.d. 0.648 1.058 20.258 19.739 19.612 79.742 79.613 79.330 n.d. n.d. n.d. 11/10 lab air n.d. 2.700 0.596 19.934 16.308 19.448 80.066 80.992 79.956 n.d. 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. 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. 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. 11/16 trailer air 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. Run 5 11/19 1 11/20 2 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 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. 11/27 11/28 11/29 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. 11/30 lab air n.d. 1.790 0.457 20.272 17.910 19.519 79.728 80.300 80.024 n.d. n.d. n.d. Run 6 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 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. 6 12/07 lab air n.d. 2.645 0.570 20.134 17.301 19.341 79.866 80.054 80.089 n.d. n.d. n.d. A V G S T D S MIN M A X 0.010 1.574 0.651 20.289 18.353 19.448 79.695 80.069 79.900 0.000 0.000 0.000 0.031 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 | 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 lo A V G A V G (%) S T D S MIN M A X 11.82 4.03 2.98 11.93 11.93 11.90 8.57 9 .50 A V G -0 .14 1 . 1 8 % 0 . 4 0 % 0 . 3 0 % 1 . 1 9 % 1 1 9 % 1 1 9 % 0 .867. 0 , 9 5 % 3.09 0.56 0.66 3.43 3 13 2 4 9 1.12 1.60 S T D S 3.00 1.30 0.77 1.93 4.74 1.30 7.04 6.03 5 95 MIN - 7 . 1 9 18.93 4 73 4.17 19.63 18.93 19.63 11.36 13.09 M A X 13.50 I no sample lost sample 5 hours of pre-mixing before feeding and sample E - 2 133 I Feed Variability | T - C F e e d A V G A V G (%) S T D S MIN M A X 8.88 4 .79 4.01 10.50 9.51 8.93 9.74 9 43 A V G 0 . 8 9 % 0 4 8 % 0 . 4 0 % 1 0 5 % 0 . 9 5 % 0 . 8 9 % 0 9 7 % , 0 . 9 5 % 2.84 0 52 0.45 3.99 4.42 4.33 1.25 1 63 SI U S MIN M A X 4.82 2.84 3.45 0.00 0.00 0.00 7.26 6,66 14.45 5 .79 4.99 18.60 15.67 15.64 11.57 12.15 A L L D A T A C O M B I N E D A V G A V G (%) S T D S MIN M A X 11.50 4.26 3.54 11.46 11.13 10.90 8.98 9,49 A V G 1 ,15% 0 . 4 3 % 0 3 5 % , 1 1 5 % 1 . 1 1 % 1 . 0 9 % 0 . 9 0 % 0 9 5 % 3.19 0.65 0.76 3.67 3.80 3.50 1.29 1.61 B I D S MIN M A X 1.30 0.77 1.93 0.00 0.00 0.00 6.03 5 .95 18 93 5 .79 4 99 19.63 18.93 19.63 11.57 13.09 no sample lost sample 5 hours of pre-mixing before feeding and sample E - 3 12* 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 Contro l Contro l T S R u n Tes t Tes t T S R u n D a y D ate F e e d A T A D Destruct ion A v e r a g e F e e d A T A D Destruct ion A v e r a g e 08/23 8 .00 6.47 - 7.04 6 .87 - 08/24 7 .62 6.21 2 2 % 7.77 5 .95 1 5 % 08/25 10.97 6 . 3 0 1 9 % 11 .02 6 .58 1 1 % 08/26 9 .64 6 . 0 3 3 2 % 7.90 6 .57 2 4 % 08/27 7 . 1 6 6 . 6 2 3 0 % 7.31 6 .56 2 6 % 08/28 9.01 6 . 7 5 2 7 % 9 .00 6 .89 2 1 % 08/29 9 . 5 9 6 . 1 6 2 8 % 9.34 6 .82 1 5 % 08/30 9 . 1 9 6 . 9 8 1 9 % 10 .98 7 .18 1 6 % 08/31 1 4 . 9 6 7.80 1 6 % 11.66 7.61 2 2 % 09/01 1 2 . 9 4 7 . 5 3 3 3 % 12 .23 8 .09 2 4 % 09/02 10 .99 7 .60 3 9 % 11 .00 7 .42 3 6 % 09/03 13 .30 6 . 6 5 4 9 % 11 .40 6 . 8 7 4 1 % 09/04 11 .38 7.84 3 7 % 11.97 7 .24 3 7 % 09/05 15 .42 6.61 4 4 % 13.98 7.31 3 6 % 09/06 13 .73 8 . 1 3 3 9 % 14.17 8 .24 3 4 % 09/07 17 .08 8 .59 3 6 % 12 .83 9 .26 3 1 % 09/08 14 .65 7.94 4 8 % 13.54 8 . 6 9 3 6 % 09/09 13.24 7 . 9 3 4 8 % 13 .49 8 . 4 8 3 7 % R u n 1 09/10 16 .23 8 .80 4 1 % 16.94 8 . 9 0 3 3 % 1 09/11 13.31 8 .60 4 1 % 13 .72 8 . 4 3 4 3 % 2 09/12 1 3 . 2 7 8 .37 4 1 % 12 .73 8 . 9 0 4 0 % 3 09/13 1 4 . 8 0 8.11 4 3 % 12 .72 9 . 1 7 3 7 % 4 09/14 13.41 8 .24 4 0 % 12 .13 9 .24 2 9 % 5 09/15 13 .12 8 .37 3 9 % 11.64 9 .38 2 5 % 6 09/16 1 3 . 0 2 8 . 6 3 3 7 % 4 0 % 12 .23 9 . 2 6 2 4 % 3 3 % 09/18 8 . 1 8 8 .08 3 8 % 9.14 8 .90 2 5 % 09/19 9 . 2 0 7 .89 2 6 % 9.67 8 .80 1 8 % 09/19 1 0 . 7 7 11.24 09/20 1 3 . 3 4 7 . 8 3 1 7 % 12.24 9 .14 9 % pre R u n 2 09/21 1 4 . 5 6 8 . 5 8 2 3 % 13.21 9.67 1 2 % 09/22 10 .90 8 . 5 3 3 4 % 13 .85 10 .13 1 7 % 09/23 11 .87 8 . 5 6 3 4 % 12.74 10 .50 2 0 % 09/24 9 .19 8.61 3 1 % 13 .73 10 .06 2 4 % 09/25 12 .47 8.40 2 1 % 11 .06 10.61 2 1 % R u n 2 09/26 1 3 . 7 4 8 . 5 2 2 4 % 15 .68 10 .13 1 9 % 1 09/27 1 5 . 5 4 9.41 2 0 % 13.27 11.10 1 8 % 2 09/28 1 1 . 3 5 9 .62 3 1 % 12.80 10.79 1 9 % 3 09/29 1 3 . 6 3 9 .34 3 1 % 12.87 10.74 2 3 % 4 09/30 10.87 9 .47 3 0 % 13.11 10 .86 1 6 % 5 10/01 11.35 8 .29 3 1 % 11 .49 10.61 1 8 % 6 10/02 1 0 . 4 2 8 .47 2 9 % 2 9 % 12.46 10 .69 1 4 % 1 8 % 10/03 9 .97 9 .88 pre R u n 3 10/04 9 .19 9 .56 10/05 4 . 4 3 9 .25 10/06 10.21 9.14 10/07 10.55 9 .84 10/08 1 2 . 3 5 10 .65 10/09 1 4 . 7 3 10 .62 10/10 8 .11 11.47 R u n 3 10/11 12.84 11.07 1 10/12 1 6 . 2 6 9 . 0 7 2 4 % 15 .19 9 . 0 7 1 8 % 2 10/13 10.90 9.91 2 0 % 10.26 9 . 6 8 2 3 % 3 10/14 12.11 9 . 3 9 3 0 % 10.39 9 . 5 5 2 2 % 4 10/15 10.13 9.01 3 1 % 15 .42 9 . 4 9 2 1 % 5 10/16 1 4 . 9 6 8 . 7 8 2 1 % 10 .95 10.14 1 6 % 6 10/17 12 .99 9.41 2 4 % 2 5 % 11 .68 10.17 1 7 % 1 9 % pre R u n 4 10/18 4 . 5 2 10.11 10/18 1.75 10/19 1.30 14.80 10/20 1.39 8 . 0 8 10/21 15.51 8 . 3 2 10/22 15.77 8 .67 10/23 1 8 . 9 3 17 .60 10/24 13.71 10 .17 10/25 1 4 . 5 2 19 .63 R u n 4 10/26 14 .69 17.63 1 10/27 1 3 . 9 3 10 .69 2 5 % 13 .72 1 2 . 8 6 1 9 % 2 10/28 1 3 . 5 6 10 .30 2 8 % 14.60 12 .59 2 6 % 3 10/29 1 1 . 5 3 10 .07 2 8 % 8.21 12.36 1 9 % 4 10/30 1 1 . 9 2 9 . 8 3 2 4 % 9 . 9 5 11 .09 9 % 5 10/31 12.27 9 .34 2 4 % 9.79 10.43 4 % 6 11/01 11 .75 8 . 8 4 2 6 % 2 6 % 9.81 9.71 - 4 % 1 2 % 11/02 10.94 13.25 A V G 3 1 % 2 3 % S T D S 9 % 1 0 % MIN 1 6 % - 4 % M A X 4 9 % 4 3 % • no s a m p l e JUJ lost s a m p l e 5 hours of p re -mix ing before f e e d i n g a n d s a m p l e E - 4 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 Contro l Contro l T S R u n Tes t Test T S R u n D a y D ate F e e d A T A D Destruct ion A v e r a g e F e e d A T A D Destruct ion A v e r a g e pre R u n 5 11/03 no feed no feed (no solubilization 11/04 no feed no feed 11/05 no feed no feed 11/06 no feed 10.71 no feed 12 . 15 11/07 no feed 11.14 no feed 11 .80 11/08 no feed no feed 11.74 pre R u n 5 11/09 15 .67 1 1 . 4 2 15 .50 11 .43 11/10 1 3 . 9 8 11.26 2 8 % 15.64 12 .02 2 2 % 11/11 9 . 1 7 11.35 2 3 % 11 .03 12 .12 2 2 % 11/12 8 . 0 7 1 0 . 8 6 1 6 % 9 .19 11 .72 1 7 % 11/13 1 3 . 4 2 9.41 1 0 % 11 . 75 10 .92 9 % 11/14 11 .20 9.61 6 % 12 .37 10.61 0 % 11/15 10 .55 9 . 7 3 1 1 % 11 .48 10.03 1 0 % 11/16 10.27 10 .57 1 0 % 10 .10 10.74 9 % 11/17 9 . 4 2 9 . 1 8 1 4 % 9 .36 9.16 1 9 % 11/18 10 .59 9 .10 1 0 % 8 .62 R u n 5 11/19 10 .29 9 .15 1 11/20 9 .64 8 . 9 5 1 1 % 7 .95 8.77 3 % 2 11/21 9 .02 8 .70 1 4 % 7.46 7 83 9 % 3 11/22 9 .22 8.41 1 3 % 8 .12 7 .60 7 % 4 11/23 8 . 9 3 8 .29 1 1 % 8 .59 7 .40 6 % 5 11/24 8 .91 1 0 % 7.39 7.26 1 0 % 6 11/25 4 . 3 6 1 3 % 1 2 % 3.91 6 .98 1 3 % 8 % pre R u n 6 11/26 10.47 9 .96 11/27 1 1 . 1 2 11 .60 11/28 1 1 . 6 3 0 % 11.71 7 .90 7 % 11/29 1 1 . 7 6 9 .03 1 8 % 11 . 15 8 .92 2 0 % 11/30 1 2 . 3 2 9.21 2 0 % 11 . 95 8 . 9 3 2 2 % R u n 6 12/01 12.33 9 . 8 2 1 8 % 11 .89 9 .43 1 9 % 1 12/02 13.24 1 0 . 3 2 1 5 % 11 . 45 9 .87 1 5 % 2 12/03 13.31 10.61 1 6 % 11 .78 10.01 1 5 % 3 12/04 13.51 10.75 1 7 % 12.76 9 .87 1 6 % 4 12/05 14.21 1 1 . 1 5 1 6 % 13.34 10.20 1 5 % 5 12/06 9.70 11.44 1 6 % 9 .28 10.39 1 8 % 6 12/07 14 .90 10 .89 1 3 % 1 6 % 14.06 10 . 05 1 5 % 1 6 % A V G 1 4 % 1 3 % S T D S 6 % 6 % MIN 0 % 0 % M A X 2 8 % 2 2 % A L L D A T A COMBINED A V G 2 5 % 2 0 % S T D S 1 1 % 1 0 % MIN 0 % •4% M A X 4 9 % 4 3 % no s a m p l e lost s a m p l e 5 hours of p re -mix ing before feed ing a n d s a m p l e N O T E : a m a n d p m s a m p l e s were a v e r a g e d to provide a 'daily' va lues for ca lcu la t ions E - 5 APPENDIX F: VFA DATA F - 1 13? p °l • 11111 « o to — I I =1= 3-1 c I a 5 to S a Kb CN r O I F - 2 \3S <u O UJ COfO mil iiiig MINI , , o k ! 2 lllll SllSf i n n i n n iggg . CD tea K —~ a t §6 1Q_ F - 3 159 Km = O N o fcjmko <u O- IS a: •a e lo m F - 4 \ 4 0  !!!;::: h r l m i ; S 6 E IIIIII 111111 III! Illl iiii 3.3 35 | 3.1 64 | 3.0 41 3.2 90  3.4 63  4.3 94  3.1 62 5.3 41 £ m a. § 6 Hill Hill lllll Hill Hill Hill Hill Hill o ^̂ 3̂ AC ET IC 1.0 07 3.2 72  2.5 00  2.1 00  2.5 00  < 2.0 25  4.3 19  1.9 00  1.8 00  3.6 87 DA TE  ro ̂  ro 1 co Si ^ ro I 1 ro ro in co CN - J CO I D CDN 6 la < O CO id 3 «~ F - 6 1*2 11 i - g l l l T 3 E a, S o o — E - Si is J2 5> c -o F - 7 143 F - 8 144 F - 9 1 4 S 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 DATE 1 9/11 a P 2 9/12 a P 3 9/13 a P 4 9/14 a P 5 9/15 a P 6 9/16 a P I SETTLED MIXED LIQUOR (Secondary Sludge) NH4 AVG 131.21 0.157 205.49 5.228 0.2S3 253.19 119.39 468.22 0.316 37.14 STDS 13.32 0.215 38.81 0.683 0.633 87 95 36.43 222.73 0.397 1.75 MIN 117.54 0.000 146.70 4.173 0.000 207.94 67.67 314.21 0.046 34.11 MAX 148.96 0.528 249.29 5.905 1.416 435.68 149.74 914.76 1.028 39.28 MEDIAN 128.16 0.097 212.30 5.269 0 228.86 135.69 395.34 0.113 37.44 lost sample below detection limit (for P04, NOx, NH4) detection limit = 0.05 mg/L (for P04, NOx, NH4) 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 NH4 1 9/11 a 34.38 5.403 207.86 0.117 26.30 35.13 5.836 245.55 1.162 26.60 P 39.63 6.276 240.30 1.044 29.56 32.22 6.642 203.60 0.874 29.32 2 9/12 a 30.30 5.689 176.39 0.845 27.65 30.89 6.067 190.20 0.727 27.27 P 30.12 3.467 185.48 0.673 27.81 32.84 4.177 203.01 0548 30.40 3 9/13 a 31.43 3.251 205.79 0.052 25.28 36.00 3.131 213.20 26.38 P 44.18 3.694 260.27 0.638 25.54 37.53 3.230 245.60 0.624 23.68 4 9/14 a 22.70 5.628 155.61 0-066 25.62 37.74 5.541 173.03 0 068 24.51 P 26.21 5.717 157.40 26.39 25.67 4.888 135.93 26.27 5 9/15 a 25.82 4.800 173.10 0.545 24.50 29.34 4.666 180.05 0.610 22.93 P 27.03 4.562 173.58 0.096 23.58 30.54 4.567 177.27 0.055 21.53 6 9/16 a 26.63 4.312 172.25 0.059 20.94 32.06 4.238 185.19 0.058 20.41 P 31.94 4.145 188.91 0.104 19.43 34.97 4.348 214.20 0.099 19.47 AVG 30.86 4.745 191.41 0.357 25.21 32.91 4.778 197.23 0.407 24.90 STDS 6.14 0.998 32.10 0.367 2.85 3.56 1.081 30.93 0.397 3.42 MIN 22.70 3.251 155.61 0.045 19.43 25.67 3.131 135.93 0.025 19.47 MAX 44.18 6.276 260.27 1.044 29.56 37.74 6.642 245.60 1.162 30.40 MEDIAN 30.21 4.681 180.93 0.1105 25.58 32.53 4.6165 196.61 0.3235 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 REACTOR, 100/0 DAY DATE TP P04 TKN NOx NH4 TP P04 TKN NOx NH4 1 9/11 a 42.38 1.644 196.00 0.994 28.00 34.23 3.381 141.68 0.927 26.61 P 39.32 2.899 180.15 1.107 28.22 38.09 3.371 173.39 1.241 27.31 2 9/12 a 38.71 2.992 174.76 1.204 28.23 39.15 3.531 177.31 1.269 28.03 P 38.63 2.058 178.44 1.160 26.39 39.45 2.263 179.76 0.815 25.28 3 9/13 a 39.03 2.195 179.88 0.982 27.01 40.18 2.794 183.14 1.245 25.63 P 36.11 2.723 168.04 1.186 25.85 40.52 3.280 183.88 1.020 26.74 4 9/14 a 30.60 4.567 153.72 0.071 28.29 29.87 5.644 165.81 0.067 28.66 P 31.89 4.189 181.94 0.066 17.82 34.95 5.211 195.86 0.075 30.55 5 9/15 a 28.85 3.180 166.34 0.808 27.94 30.32 3.511 168.57 0.785 26.60 P 30.08 2.574 171.02 0.251 26.89 30.54 2.861 176.91 0.861 26.16 6 9/16 a 30.15 2.447 151.49 0.281 26.68 31.82 2.853 175.92 0.332 24.10 P 25.40 2.513 146.00 0.309 25.14 29.60 3.080 169.22 1.180 23.98 AVG 34.26 2.832 170.64 0.702 26.37 34.89 3.482 174.29 0.818 26.64 STDS 5.38 0.839 14.49 0.464 2.88 4.39 0.983 13.07 0.437 1.87 MIN 25.40 1.644 146.00 0.066 17.82 29.60 2.263 141.68 0.067 23.98 MAX 42.38 4.567 196.00 1.204 28.29 40.52 5.644 195.86 1.269 30.55 MEDIAN 34.00 2.6485 172.89 0.895 26.95 34.59 3.3255 176.42 0.894 26.61 G-2 IS1 RUN 2 - CONTROL 100/0, TEST 65/35 - NUTRIENT DATA (mg/L as N or P) AVG 103.37 0.042 155.96 7.218 0.064 235.01 132.82 437.06 0.867 36.47 STDS 17.01 0.028 29.04 0.636 0.051 28.70 3.03 60.60 0.437 0.48 MIN 92.55 0.000 134.87 6.089 0.012 202.31 129.71 354.30 0.552 36.11 MAX 137.40 0.083 213.41 7.954 0.140 280.05 136.77 512.66 1.618 37.35 MEDIAN 97.19 0.0405 146.56 7.308 0.0475 226.41 132.24 422.03 0.6285 36.27 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) TEST REACTOR FEED, 65/35 DAY DATE TP P04 TKN NOx NH4 TP P04 TKN NOx NH4 1 9/27 a 29.63 7.912 164.87 0.786 16.30 149.50 43.70 412.18 0.123 29.89 P 42.72 5.257 209.91 0.128 21.62 134.33 48.23 423.70 0.195 34.91 2 9/28 a 31.67 3.915 165.87 0.058 18.33 153.03 56.78 400.50 0.552 30.70 P 35.34 5.132 181.64 0.113 21.69 147.48 79.48 387.50 0.552 33.58 3 9/29 a 45.53 4.400 245.43 0.579 20.21 145.03 50.61 414.60 0.482 29.51 P 38.90 5.020 226.77 21.45 164.88 47.88 491.88 0.375 29.36 4 9/30 a 36.87 4.346 203.01 0.067 19.57 162.95 57.27 446.20 0.410 31.45 P 30.84 4.489 179.37 0.072 21.04 158.00 60.46 442.55 0.527 35.63 5 10/01 a 35.63 4.410 185.33 0.188 21.16 163.60 46.63 433.13 0.450 28.73 P 42.26 4.445 205.65 0.690 21.78 157.03 49.47 429.00 0.327 29.40 6 10/02 a 37.94 4.443 198.20 0.618 21.23 158.50 48.55 457.25 0.367 28.91 P 41.64 4.674 232.70 0.684 23.00 156.85 53.99 444.65 0.445 35.47 AVG 37.41 4.870 199.89 0.362 20.61 154.26 53.59 432.34 0.400 31.46 STDS 5.07 1.030 25.88 0.302 1.81 8.92 9.53 27.76 0.135 2.69 MIN 29.63 3.915 164.87 0.058 16.30 134.33 43.70 387.50 0.123 28.73 MAX 45.53 7.912 245.43 0.786 23.00 164.88 79.48 491.88 0.552 35.63 MEDIAN 37.40 4.467 200.60 0.1205 21.19 156.94 50.04 433.55 0.4275 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 REACTOR, 65/35 DAY DATE TP P04 TKN NOx NH4 TP P04 TKN NOx NH4 1 9/27 a 52.46 8.380 205.43 2.331 56.85 151.45 63.61 438.48 0.524 145.24 P 46.19 6.230 256.80 0.130 51.95 132.33 60.67 381.58 0.297 142.43 2 9/28 a 43.35 6.251 237.51 0.178 56.28 104.05 42.45 337.95 0.440 109.24 P 46.67 5.173 236.21 0.726 52.86 154.88 63.84 445.95 0.291 143.61 3 9/29 a 43.49 5.521 228.99 0.330 52.26 172.90 66.31 488.63 0.505 146.02 P 51.95 8.844 239.10 0.219 60.55 180.08 64 45 512.10 0.222 143.28 4 9/30 a 54.62 5.200 257.42 0.261 52.47 159.63 62.59 463.98 0.509 144.76 P 49.55 5.717 258.26 0.242 52.19 150.30 56.22 420.40 0.402 146.73 5 10/01 a 43.38 5.678 217.55 1.076 50.90 151.85 68.40 404.13 0.470 139.16 P 43.64 5.717 226.89 1.039 48.80 70.43 0.549 145.17 6 10/02 a 38.64 6.721 204.98 1.317 56.23 166.83 73.01 443.40 0.440 156.22 P 38.52 5.430 200.40 1.098 49.43 146.83 388.23 0.236 148.70 AVG 46.04 6.239 230.79 0.750 53.40 151.92 62.90 429.53 0.407 142.55 STDS 5.22 1.200 20.69 0.656 3.42 20.56 8.20 50.16 0.116 11.27 MIN 38.52 5.173 200.40 0.178 48.80 104.05 42.45 337.95 0.222 109.24 MAX 54.62 8.844 258.26 2.331 60.55 180.08 73.01 512.10 0.549 156.22 MEDIAN 44.91 5.717 232.60 0.528 52.37 151.85 63.72 438.48 0.44 144.97 G - 3 162- RUN 3 - C O N T R O L 100/0, TEST 35/65 - NUTRIENT DATA (mg/L as N or P) DAY DATE 10/12 a UNSETTLED MIXED LIQUOR (am, a-Side & pm, B-side) NH4 10/13 a TP P 0 4 TKN NOx 107.931 98.46 0.0571 187.521 159.17 229.691 1391 469.091 6.0391 171.. 125.11 311.33 0.112| 0.155 36.65 32.51 3 r 10/14 a 115.97 196.05 7.009 0.101 328.05 122.77 705.79 0.152 29.39 P 49.41 0.034 141.03 0.202 13.327 4 10/15 a 115.61 0.004 189.20 8.595 0.113 305.85 149.42 761.06 0.095 34.71 P 59.85 0.047 157.40 0.803 13£91 5 10/16 a 119.00 0.000 191.25 5.866 263.89 129.26 487.84 0.117 30.15 P 70.31 172.80 0.928 12.503 182.06 127.82 326.25 0.162 30.77 6 10/17 a 131.31 213.92 7.108 _____ 218.44 135.54 426.34 0.131 29.38 P 76.95 r, n* 181.34 1.058 250.01 137.77 478.65 0.112 33.45 AVG 94.48 0.020 178.97 4.532 5.248 243.67 133.46 495.79 0.130 32.13 STDS 28.25 0.026 21.56 3.352 6.724 55.16 8.89 161.75 0.024 2.67 MIN 49.41 0.000 141.03 0.202 0.000 171.34 122.77 311.33 0.095 29.38 MAX 131.31 0.060 213.92 8.595 13.591 328.05 149.42 761.06 0.162 36.65 MEDIAN 103.19 0.003 184.43 5.9525 0.107 239.85 132.40 473.87 0.124 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) TEST REACTOR FEED, 35/65 DAY DATE TP P04 TKN NOx NH4 TP P04 TKN NOx NH4 1 10/12 a 37.73 4.993 240.48 0.763 18.81 307.84 93.41 777.00 0.091 32.27 P 48.62 8.180 284.88 0.872 24.73 311.36 98.67 800.63 0.207 36.52 2 10/13 a 31.53 4.042 187.37 0.936 16.98 232.95 80.30 593.33 0.127 28.74 P 40.94 4.691 233.24 0.798 18.16 164.40 83.10 410.44 0.118 28.79 3 10/14 a 36.29 4.447 199.47 0.058 17.31 197.74 84.81 435.00 0.147 27.41 P 38.82 6.932 214.83 0.797 22.41 202.39 84.72 490.69 0.164 29.62 4 10/15 a 31.77 4.276 190.56 0.728 18.09 349.65 105.93 855.56 0.115 31.66 P 38.91 5.068 224.18 0.930 19.36 334.76 115.38 837.30 0.125 36.22 5 10/16 a 52.91 4.558 266.43 0.707 18.97 201.15 72.08 543.56 0.083 25.94 P 48.35 5.925 268.73 CL560 21.54 192.04 72.76 535.50 0.124 28.65 6 10/17 a 44.90 5.568 267.29 20.69 287.89 92.22 717.04 0.154 28.82 P 44.27 4.675 233.15 0.066 22.50 236.81 103.44 530.25 0.087 31.30 AVG 41.25 5.280 234.22 0.604 19.96 251.58 90.57 627.19 0.129 30.49 STDS 6.71 1.215 32.63 0.347 2.40 63.37 13.42 161.07 0.036 3.27 MIN 31.53 4.042 187.37 0.037 16.98 164.40 72.08 410.44 0.083 25.94 MAX 52.91 8.180 284.88 0.936 24.73 349.65 115.38 855.56 0.207 36.52 MEDIAN 39.92 4.842 233.19 0.7455 19.17 234.88 88.52 568.44 0.1245 29.22 RUN 3 - CONTROL 100/0, TEST 35/65 - NUTRIENT DATA (mg/L as N or P) DAY DATE c TP ONTROL f P04 iTAD REA( TKN iTOR, 100 NOx 0 NH4 TP TEST AT/ P04 \D REACT TKN DR, 35/65 NOx NH4 1 10/12 a 40.53 7.844 221.76 0.930 55.20 184.20 103.01 434.59 0.159 130.85 P 46.80 9.247 241.59 0.811 61.44 265.80 113.06 660.64 0.184 138.05 2 10/13 a 58.52 15.262 272.40 0.970 72.22 243.86 115.61 630.04 0.200 125.21 P 50.73 11.200 283.89 0.151 72.79 223.39 120.42 594.49 0.221 158.42 3 10/14 a 62.21 16.850 292.83 0.196 77.04 205.95 118.45 535.43 0.232 139.62 P 49.77 10.727 272.15 0.801 70.08 205.88 107.08 516.60 0.229 137.54 4 10/15 a 47.36 10.906 262.25 0.853 72.16 257.93 111.27 661.16 0.236 132.01 P 47.72 11.199 255.83 0.186 68.43 227.85 118.63 590.81 0.246 138.53 5 10/16 a 51.32 12.638 243.63 0.913 68.84 318.64 125.46 776.86 0.217 149.77 P 58.44 10.231 271.41 0.199 92.63 294.38 127.13 747.23 0.298 150.43 6 10/17 a 65.57 11.719 299.34 0.848 68.00 309.98 119.63 777.53 0.210 149.83 P 58.31 9.528 287.27 0.863 80.3: 225.68 124.43 591.86 0.364 150.67 AVG 53.10 11.446 267.03 0.643 71.60 246.96 117.02 626.44 0.233 141.74 STDS 7.40 2.507 23.10 0.343 9.32 43.20 7.37 105.77 0.053 9.98 MIN 40.53 7.844 221.76 0.151 55.20 184.20 103.01 434.59 0.159 125.21 MAX 65.57 16.850 299.34 0.970 92.63 318.64 127.13 777.53 0.364 158.42 MEDIAN 51.02 11.0525 271.78 0.8295 71.12 235.86 118.54 612.26 0.225 139.08 G-4 I S3 RUN 4 - CONTROL 100/0, TEST 0/100 - NUTRIENT DATA (mg/L as N or P) AVG 139.55 0.051 225.70 8.340 0.013 103.99 0.043 239.16 1.667 9.111 STDS 10.68 0.034 19.97 0.941 0.016 19.37 0.100 38.62 0.320 6.936 MIN 125.81 0.000 200.79 7.071 0.000 67.29 0.000 162.80 1.256 0.000 MAX 152.55 0.084 251.52 9.801 0.036 117.59 0.246 262.98 2.008 15.545 MEDIAN 140.20 0.066 225.86 8.3085 0.0125 110.56 0.0015 254.72 1.706 13.9775 lost sample below detection limit (for P04, NOx, NH4) detection limit = 0.05 mg/L (for P04, NOx, NH4) 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 NH4 1 10/27 a 39.66 4.430 221.55 1.014 20.16 355.95 150.18 746.80 0.051 35.07 P 37.07 5.881 212.58 0.831 24.82 433.55 166.54 914.70 0.146 38.53 2 10/28 a 42.51 4.680 244.47 0.901 20.43 328.35 132.40 657.10 0.091 32.40 P 41.51 7.683 238.53 0.960 26.07 400.15 170.51 859.85 0.098 35.00 3 10/29 a 36.86 4.180 210.66 0.923 20.66 262.55 122.90 477.25 0.086 28.08 P 5.261 0.899 22.83 309.80 137.78 591.00 0.199 30.09 4 10/30 a 51.02 4.465 261.75 0.971 21.74 314.90 127.82 582.55 0.096 27.54 P 41.01 5.682 230.67 1.027 23.72 340.00 160.83 671.45 0.114 30.82 5 10/31 a 41.55 4.595 225.24 0.985 21.91 318.55 130.72 618.55 0.105 26.55 P 39.35 5.374 223.85 0.764 23.59 294.40 157.11 562.10 0.146 30.39 6 1101 a 46.59 4.258 247.82 0.879 20.85 310.15 125.21 627.95 0.128 26.63 P 57.14 5.192 290.42 0.805 22.94 284.35 51.62 567.25 0.175 30.42 AVG 43.11 5.140 237.05 0.913 22.48 329.39 136.14 656.38 0.120 30.96 STDS 6.19 0.979 23.50 0.083 1.86 48.13 31.49 127.00 0.041 3.72 MIN 36.86 4.180 210.66 0.764 20.16 262.55 51.62 477.25 0.051 26.55 MAX 57.14 7.683 290.42 1.027 26.07 433.55 170.51 914.70 0.199 38.53 MEDIAN 41.51 4.936 230.67 0.912 22.37 316.73 135.09 623.25 0.1095 30.40 RUN 4 - CONTROL 100/0, TEST 0/100 - NUTRIENT D A T A (mg/L as N or P) DAY DATE C TP ONTROL t P04 \TAD REA( TKN ;TOR , 100 NOx 0 NH4 TP TEST AT/ P04 \D REACT TKN OR, 0/100 NOx NH4 1 10/27 a 50.97 8.687 264.60 1.104 82.77 342.75 225.34 801.00 0.608 247.32 P 56.60 15.060 243.87 0.968 84.77 293.40 218.44 653.25 0.746 252.41 2 10/28 a 79.73 20.675 310.77 0.960 93.02 365.35 217.99 819.55 0.552 252.32 P 49.01 11.027 264.77 0.966 75.99 373.35 207.79 875.30 0.325 260.61 3 10/29 a 53.84 11.966 255.84 0.967 75.81 433.85 214.79 942.70 0.516 269.32 P 55.55 9.650 272.27 1.124 76.26 434.85 216.61 976.85 0.568 275.80 4 10/30 a 65.51 13.680 298.73 0.941 77.94 330.15 210.39 744.80 0.401 263.06 P 64.02 15.490 281.66 0.924 81.15 365.55 205.99 841.55 0.515 264.38 5 10/31 a 53.19 13.048 255.08 0.915 79.64 360.80 208.94 812.20 0.526 254.78 P 53.22 11.539 263.21 0.206 75.66 337.15 207.59 769.15 0.449 246.79 6 1101 a 66.41 16.314 285.20 0.926 83.07 266.55 208.51 553.80 0.412 24.53 P 60.24 15.065 268.77 1.030 80.18 356.65 209.28 762.05 0.464 248.03 AVG 59.02 13.517 272.15 0.919 80.52 355.03 212.64 796.02 0.507 238.28 STDS 8.68 3.286 19.18 0.235 5.03 48.51 5.91 115.59 0.110 67.94 MIN 49.01 8.687 243.87 0.206 75.66 266.55 205.99 553.80 0.325 24.53 MAX 79.73 20.675 310.77 1.124 93.02 434.85 225.34 976.85 0.746 275.80 MEDIAN 56.07 13.364 266.77 0.963 79.91 358.73 209.84 806.60 0.5155 253.60 G - 5 154 R U N 5 - C O N T R O L 0/100, T E S T 0/100 solubil ized - 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) D A Y D A T E 1 11/20 a p 2 11/21 a p 3 11/22 a I P 4 11/23 a I P 5 11/24 a p 6 11/25 a 11/26 a | A V G 157.47 0 .050 250 .40 7 .575 0.025 109.58 0.079 234.94 6.437 0.042 S T D S 13.99 0 .038 18.08 0.518 0,024 12.25 0 .078 19.95 2.445 0 .033 MIN 1 4 - . 8 6 0 .000 229 .47 6 .672 0 .000 99.27 0.026 209.19 3,313 0 .002 M A X 175.41 0 .089 281 .16 8 . 0 2 5 0 .059 131.48 0.232 259.59 10.082 0.076 M E D I A N 155.66 0 .0605 249 7 : 7.757 0 .0225 105.09 0.0545 230.51 6.411 0 .0455 lost s a m p l e below detection limit (for P 0 4 , NOx, NH4) detection limit = 0 .05 mg/L (for P 0 4 , NOx , NH4) R U N 5 - C O N T R O L 0/100, T E S T 0/100 solubi l ized - N U T R I E N T D A T A (mg/L a s N or P) CONTROL REACTOR FEED, mm J TEST R E A C T O R F E E D , 6/106 solubi l ized D A Y D A T E T P so lub leTP P 0 4 T K N so lub leTKN NOx N H 4 T P solubleTP P 0 4 T K N so lub leTKN N O x N H 4 1 11/20 a 241,50 41 .00 4 2 . 0 8 536.00 7 48 0.182 5 450 2 4 7 . 4 5 78.60 76.22 536 .70 79 .58 0 .293 14.93 P 3 0 5 . 4 5 5 3 . 0 3 53.34 668,00 11.04 0 .102 7.750 2 3 4 . 4 5 122.44 128.07 502.20 130.91 0 .237 32.30 2 11/21 a 3 1 3 . 1 5 40.07 42 .02 679.10 7.53 0 .143 4 .770 250 .50 75.41 73.B0 541 .10 65.14 0.307 15,04 P 217 .70 49.43 53.72 451.45 11.75 0.154 6 .040 2 0 7 . 0 5 130,43 121.81 4 6 5 , 5 5 117,45 0 .162 37,15 3 11/22 a 2 2 3 . 4 5 38 .63 42.34 465 .10 5.58 0.184 5.420 2 5 3 . 1 5 82 ,09 84.77 554,75 71.44 0 .218 15,29 P 2 8 1 . 2 5 56.67 65.99 5 8 1 . 1 5 10.30 0.147 6 .840 258.90 141.75 140.12 5 3 8 . 0 5 120.26 0 .173 4 6 . 5 5 4 11/23 a 2 3 7 . 7 5 46 .49 47 .47 460.15 5.52 0.200 5.690 2 4 4 . 2 0 9 5 . 5 5 87 .66 5 5 0 . 9 5 6 4 . 0 5 0.234 16.74 P 2 8 4 . 7 5 66 .39 5 9 . 4 8 626,00 6.18 0 .143 7.100 2 6 3 . 2 5 137.44 145.40 596.70 109.43 0,282 56 .49 5 11/24 a 2 9 9 . 0 5 59 .07 61.94 667.45 B.45 0.171 7 .110 2 9 6 . 3 5 101.36 98 .62 7 0 3 . 9 5 6 6 . 4 5 0 .379 19.49 P 2 9 6 . 9 5 71 .70 7 8 . 3 9 6 1 6 . 4 5 10.79 0.171 10.850 282 .70 140.44 143.25 6 3 7 . 6 5 111.71 0.231 53.41 6 11/25 a 76 .30 41 .03 45.64 100.65 8.32 0.161 6 .970 137.30 6 0 . 1 5 62.05 200 .40 52 .69 0 .148 19.69 11/26 a 179.10 62 .88 63.38 402 .30 17.28 0.571 13.580 110.85 89.10 80.34 2 0 5 . 2 5 81 . 5 3 0.487 2 5 . 1 8 A V G 2 4 6 . 3 7 52 .20 54.65 5 2 1 . 1 5 9.18 0.194 7.298 2 3 2 . 1 8 104.56 103.51 502.77 89 .22 0 .263 29.44 S T D S 6 8 . 0 0 11.22 11.48 163.62 3 .33 0.121 2 .526 55 .48 26.72 30,33 153.06 2 6 . 8 8 0.097 15.46 MIN 76.30 38 .63 42 .02 100.65 5.52 0 .102 4 .770 110.85 60 1 5 62 ,05 200 .40 52 .69 0 .148 14.93 M A X 3 1 3 . 1 5 71 .70 7 8 . 3 9 679 .10 17.28 0.571 13.580 2 9 6 . 3 5 141.75 145.40 7 0 3 . 9 5 130.91 0 .487 5 6 . 4 9 M E D I A N 2 6 1 . 3 8 51 .23 53 .53 558.58 8 . 3 9 0 .166 6 .905 248 .98 9 8 . 4 6 93.14 539.58 8 0 . 5 5 0 .2355 22.44 R U N 5 - C O N T R O L 0/100, T E S T 0/100 solubil ized - N U T R I E N T D A T A (mg/L a s N or P) D A Y D A T E T P i so lub leTP O N I K O L P 0 4 A T A D R E / T K N CTOR.6/10 so lub leTKN 3 NOx N H 4 T P T_< so lub leTP T A T A D R P 0 4 E A C T 6 R , T K N 0/100 solubil s o l u b l e T K N zed NOx N H 4 1 11/20 a 3 1 1 . 5 5 167.6? 154.85 763.80 254.64 6.256 182.02 3 1 0 . 5 5 187,35 166.00 7 4 7 . 3 5 3 0 1 . 0 5 0 .229 2 0 2 . 7 9 P 2 7 4 . 0 0 174.80 154.84 6 7 2 . 9 5 2 8 4 . 3 3 0 .229 174.54 2 7 7 . 6 5 165.66 165.41 643 .80 264 .77 0 .272 193.80 2 11/21 a 343.55 169.25 154.52 8 3 7 . 2 5 274.17 0.260 166.83 2 6 6 . 3 0 176.01 159.16 620.20 2 6 6 . 3 6 0 .265 185.30 P 2 7 2 . 8 5 169.41 149.30 6 8 0 . 7 5 265 .46 0 .239 155.12 295 .40 181.91 157.63 6 7 0 . 3 5 267.84 0 .249 179.36 3 11/22 a 2 9 7 . 8 0 166.62 148.45 699 .40 262 .98 0 .260 151.09 2 6 2 . 5 5 169.56 155.79 6 0 9 . 4 5 259 .67 0.256 173.72 P 3 1 3 . 4 5 168.86 149.74 700.75 272.52 0 .335 149.64 262 .10 165.69 150.54 5 6 9 . 4 5 2 3 0 . 6 7 0 .309 173.73 4 11/23 a 2 2 6 . 6 0 176.04 156.66 504.90 266 .66 0 .390 153.62 195.20 166.08 148.66 4 5 7 . 2 5 2 5 5 . 6 9 0 .255 170.75 P 2 9 4 . 8 5 162.92 152.37 650.70 242.31 0 .488 138.98 2 3 9 . 5 5 160.77 134.19 490 .20 2 1 5 . 7 2 0 .378 169.74 5 11/24 a 2 8 9 . 6 5 177.08 155.58 6 4 8 . 7 5 267 .30 0.536 150.77 239 .20 164.81 152.07 421.10 2 1 7 . 4 6 0 .394 171.06 P 228 .50 172.20 156.29 4 9 6 . 7 5 255 .92 0 .485 146.53 2 5 9 . 9 5 167.09 149,73 539.15 244 ,40 0.361 175.50 6 11/25 a 2 3 1 . 5 5 173.96 155.97 543.35 258.62 0 .435 154.36 2 9 7 . 0 0 173.57 156.10 590 .70 2 5 5 . 6 9 0.386 190.70 11/26 a 277 .90 152.72 143.57 645.70 225.96 0.474 140.62 2 3 7 . 3 5 141.20 131.54 520.05 192.12 0.557 174 .46 A V G 250 .19 169.24 152.0,3 6 5 3 . 7 5 260 .90 0.366 155.34 261 .90 168.31 152.24 5 7 3 . 2 5 2 4 7 . 6 2 0,326 180.08 S T D S 36 .59 6.70 4.07 100.12 15.36 0 .115 12.97 31.71 11.52 10.63 93.44 29 .37 0 .094 10.67 MIN 226 ,60 152.72 143.57 4 9 6 . 7 5 225 .96 0 .229 138.98 195.20 141.20 131.54 421 .10 192.12 0 .229 169.74 M A X 3 4 3 . 5 5 177.08 156.66 837.25 2 8 4 . 3 3 0.536 182.02 310.55 187.35 166.00 747.35 3 0 1 . 0 5 0.557 2 0 2 . 7 9 M E D I A N 2 8 3 . 7 8 169 33 154.68 6 6 1 . 8 3 264 .22 0.3625 152.36 2 6 2 . 3 3 166.58 153,93 580 .08 255 .69 0 .2905 174.98 G - 6 ISS P R I M A R Y S L U D G E S E T T L E D M I X E D L I Q U O R (Secondary Sludge) D A Y D A T E T P P 0 4 | T K N NOx | N H 4 T P P 0 4 | T K N NOx | N H 4 1 12/02 a 37 .76 3.711 205 .46 0 .675 2 8 . 8 3 165.90 81.17 285.38 0 .960 16.116 p 2 12/03 a 31 .58 3 .256 191.66 0 .750 31 .68 530 .40 98.54 1153.31 1.200 17 .013 P 3 12/04 a 31.041 3.3751 194.63 0 .729 30.77 498 .68 128.22 1094.85 0 .880 18.669 P 4 12/05 a 2 7 . 5 6 3.131 181.02 0 .853 31.00 684.90 108.67 1512.53| 1.110 18.393 P 5 12/06 a 2 4 . 7 5 3.011 153.54 0.818 34 .37 3 6 0 . 3 8 1 7 1 5 . 0 5 1 14.186 P 6 12/07 a 22.021 2 .963 143.45 0 .710 2 7 . 7 4 665.63 127.43 1428.98 0 .850 19.281 P A V G 2 9 . 1 2 3.241 178.29 0.756 30 .73 484.31 90.67 1032.18 0 .833 14.808 S T D S 5.59 0.276 24 .57 0.067 2.31 196.05 47.87 460 .56 0.430 6 .758 MIN 22.02 2 .963 143.45 0 .675 27.74 165.90 0.00 288 .36 0.000 0 .000 M A X 3 7 . 7 6 3.711 205.45 0 .853 34.37 684.SO 128.22 1512.53 1.200 19.281 M E D I A N 29 .30 3.1S35 186.34 0.7395 30 .88 514.54 108.67 1124.08 0.96 17.703 lost sample below detection limit (for P 0 4 , NOx , NH4) detection limit = 0 .05 mg/L (for P 0 4 , NOx , NH4) R U N 6 - C O N T R O L 35/65, T E S T 35/65 solubil ized - N U T R I E N T D A T A (mg/L a s N or P) CONTROL REACTOR FEED, SS/SS TEST REACTOR FEED, 35/65 solubil z e d D A Y D A T E T P so lub leTP P 0 4 T K N so lub leTKN NOx N H 4 T P so lub leTP P 0 4 T K N s o l u b l e T K N N O x N H 4 1 12/02 a 314.80 78 . 6 5 7 9 .37 729.40 17.03 0 .740 23 .39 338.20 90.05 742 .80 1.050 27 .55 P 314 .40 125.39 131.05 734 .60 2 0 . 4 5 0 .980 27.11 2 9 3 . 5 5 129.33 133.73 665 65 6 8 . 9 3 1.190 72 .66 2 12/03 a 283,10 81.92 85.14 6 4 5 . 2 5 17.09 0 .700 2 1 . 1 5 272.85 84 .45 91.84 628 65 4 6 . 6 5 1.200 30.15 P 2 7 7 . 4 0 130.88 136.29 637 .40 22 .02 0 .820 31 .89 283.80 130.79 139.09 649.05 7 3 . 8 3 1.000 84 .07 3 12/04 a 2 5 7 . 8 5 8 2 . 8 3 90.61 5 7 4 . 1 5 17.99 0,080 25.04 285 .20 99.74 104.12 6 2 8 . 8 5 6 4 . 1 6 1.070 41 .05 p 256 .60 116.66 135.67 597.05 26 .63 1.050 31 .43 396.70 138.03 145.37 906.60 6 5 . 7 6 1.150 92.41 4 12/05 a 351 25 7 6 . 5 3 84 .58 850.80 18.72 1.010 22.31 322.20 96 .66 95.94 7 2 4 . 5 5 3 8 . 5 2 1.030 29,84 P 329.45 122.94 126.62 921.20 26 .96 0 .910 2 9 . 1 3 219 .40 142.26 147.32 507 .10 6 8 . 0 0 0,950 82 .23 5 12/06 a 152.05 69 .63 72 .98 3 2 7 . 2 5 15.20 0 .820 22 .50 179.00 72 .06 7 8 . 9 9 3 6 6 . 3 5 31 .23 0 .700 2 6 . 8 5 p 187.65 9 1 . 8 6 95 .10 429 .80 23 .52 1.070 23.52 168.55 107.54 111.76 3 4 7 . 7 0 7 1 . 7 0 1.040 72.60 6 12/07 a 339 .40 89.16 90 .65 814.60 17.91 0 .720 2 4 . 6 6 297 .20 103.04 105.31 656 .70 4 6 . 2 9 0 .980 36.10 P 334.00 136.58 139.40 776.50 23 .36 0 S10 32,77 259 .70 146.31 155.69 599.05 7 7 . 4 9 1.100 97 .47 A V G 2 8 3 . 1 6 100.25 105.62 669.83 20 .57 0.818 26.24 276 .36 113.65 116.60 6 1 8 . 5 9 59 .32 1.038 57 .75 S T D S 61 .93 2 4 . 2 6 25 .67 172.44 3.89 0 .265 4.11 64 .60 2 4 . 9 7 26 .22 154.99 15.74 0 .133 28 .07 MIN 152.05 69 .63 72 .98 327.25 15.20 0 .080 2 1 . 1 5 168.55 72 .06 7 8 . 9 9 347 .70 31 .23 0 .700 2 6 . 8 5 M A X 351.25 136.58 139.40 921.20 26 .96 1.070 32.77 396.70 146.31 155.69 906.60 7 7 . 4 9 1.200 97 .47 M E D I A N 2S8.75 90.51 92.88 687.33 19.58 0 .865 2 4 . 8 5 284 .50 107.54 108.54 6 3 8 . 9 5 6 5 . 7 6 1.045 56 .83 R U N 6 - C O N T R O L 35/65, T E S T 35/65 solubil ized - N U T R I E N T D A T A (mg/L as N or P) D A Y D A T E T P C" so lub leTP O N T R O L P 0 4 A T A D RE/ T K N ^CTOR, 35/6 so lub leTKN 5 N O x N H 4 T P TEE so lub leTP T A T A D R P 0 4 E A C T O R , T K N 35/65 SOIUDI s o l u b l e T K N zed NOx N H 4 1 12/02 a 237 .20 169.65 139.1? 559,00 259,37 1.630 194.53 265 .50 196,62 152,78 621 .60 2 ? 9 . 9 6 1.226 300.59 p 287 .40 177.77 143.34 672 .10 266,16 1.610 2 0 9 . 9 3 2 3 6 . 7 0 188.51 152.00 568.70 2 7 1 . 6 4 1.430 321,84 2 12/03 a 2 4 0 . 6 5 184.68 145.56 558 .60 280,54 1.480 197.19 246 .90 195.59 150.86 584 .30 2 8 8 . 7 5 1.310 315 .00 p 2 2 6 . 3 5 196.86 145.48 527.70 251 .88 1.350 312.49 246 .00 191.69 151.76 559.90 286.01 1.260 380.61 3 12/04 a 245 .00 204 .26 151 67 568,75 264 .57 1.390 308.26 236.00 191.09 152.69 4 9 4 . 1 2 2 8 0 . 2 8 1.210 3 4 9 . 3 3 P 278,80 203 .09 153.36 633.25 265 .22 1.290 350.52 249 .60 182.57 153.57 560 .30 279.81 1.110 304.14 4 12/05 a 242 .20 195.74 162.87 556,80 285 .48 1.450 308 .76 2 4 4 . 1 0 189.50 165.73 558 .50 2 8 5 . 4 4 1.460 2 8 3 . 0 5 p 2 5 3 . 9 5 212.91 157.85 574.05 263 .70 1.490 262 .92 2 3 5 . 0 5 194,09 158.59 555.80 275.54 1.540 242.06 5 12/06 3 2 4 9 . 0 5 2 0 0 . 2 5 158.61 577 ,10 265,73 1.310 2 5 8 . 9 5 2 0 7 . 1 5 188,24 157.97 4 8 5 . 2 5 2 7 1 . 0 2 1,500 310.84 P 2 6 5 . 4 5 202.31 155.70 620.45 285,81 1,360 3 7 5 . 7 3 2 2 9 . 6 5 194.99 157.19 498.40 289.37 1.220 338.61 6 12/07 a 234 .00 193.56 149.54 566 .70 198.11 0 .700 338 .96 2 2 4 . 8 0 198.11 153.10 510 .40 2 8 7 . 6 9 1.460 324,31 p 2 5 4 . 2 0 202.97 : 5.8.3? 594 l i 281.31 1.590 339.68 184.10 188.01 154.37 3 9 9 . 2 5 281.31 1.290 292.14 A V G 2 5 1 . 1 9 195 29 151.79 584.05 264.00 1.388 288.16 233 .96 191.58 155.05 5 3 3 . 1 3 281,40 1.334 313.54 S T D S 18.18 12.43 7.27 39 .86 2 3 . 4 2 0 . 2 4 5 62 .42 2 1 . 2 9 4 .48 4.21 58,64 6.31 0 .138 34.84 MIN 2 2 6 . 3 5 169.05 139.17 527.70 198.11 0 .700 194.53 184.10 182.57 150.86 3 9 9 . 2 5 271,02 1.110 2 4 2 . 0 6 M A X 287 .40 212.91 162.87 672 .10 285.81 1.630 375.73 265,50 198.11 165.73 621 .60 289.37 1,540 380,61 M E D I A N 2 4 7 . 0 3 198,56 152.52 571 .40 265 .47 1.42 308.51 2 3 7 . 3 5 191.39 153.34 5 5 7 . 6 5 280 .79 1,3 312.92 G - 7 \S<o APPENDIX H: TOC DATA H - 1 \5? RUN 1 - CONTROL 100/0, TEST 100/.0 - TOC DATA (mg/L) DAY DATE Control Feed Test Feed Control ATAD Test ATAD 1 9/11 a 591 591 615 615 P 570 570 622 622 2 9/12 a P 3 9/13 a 538 538 588 588 P 555 555 550 550 4 9/14 a P 5 9/15 a 603 603 678 678 P 563 563 714 714 6 9/16 a P AVG STDS MIN MAX MEDIAN 570 570 11928 628 24 24 59 59 538 538 550 550 603 603 714 714 566 566 619 619 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) DAY DATE Control Feed Test Feed Control ATAD Test ATAD 1 9/27 a 795 777 691 1042 P 749 771 682 1021 2 9/28 a P 3 9/29 a 623 707 680 1008 P 829 834 759 984 4 9/30 a P 5 10/01 a 708 802 681 939 P 685 886 684 975 6 10/02 a P AVG STDS MIN MAX MEDIAN 731 796 696 995 75 61 31 37 623 707 680 939 829 886 759 1042 728 789 683 996 H - 2 ISS RUN 3 - CONTROL 100/0, TEST 35/65 - TOC DATA (mg/L) DAY DATE Control Feed Test Feed Control ATAD Test ATAD 1 10/12 a P 2 10/13 a 524 778 590 938 P 570 760 560 966 3 10/14 a P 4 10/15 a 484 1076 530 865 P 564 1184 525 898 5 10/16 a P 594 820 608 975 6 10/17 a 580 864 506 1013 P AVG STDS MIN MAX MEDIAN 553 914 553 943 41 175 40 54 484 760 506 865 594 1184 608 1013 544 821 528 918 RUN 4 - CONTROL 100/0, TEST 0/100 - TOC DATA (mg/L) DAY DATE Control Feed Test Feed Control ATAD Test ATAD 1 10/27 a 547 1352 543 1531 P 565 1185 542 1335 2 10/28 a P 3 10/29 a 602 741 507 1559 P 659 720 542 1454 4 10/30 a P 5 10/31 a 656 1023 584 1252 P 613 943 542 1229 6 11/01 a P AVG STDS MIN MAX MEDIAN 520 994 543 1393 233 248 24 142 0 720 507 1229 659 1352 584 1559 608 983 542 1395 H - 3 159 RUN 5 - CONTROL 0/100, TEST 0/100 solubilized- TOC DATA (mg/L) DAY DATE Control Feed Test Feed Control ATAD Test ATAD 1 11/20 a 49 320 472 502 P 52 568 522 468 2 11/21 a 50 298 512 426 P 44 517 508 422 3 11/22 a 45 306 478 ' 465 P 45 519 572 325 4 11/23 a 45 346 496 363 P 41 527 562 352 5 11/24 a 43 273 687 377 P 42 500 573 381 6 11/25 a 45 231 608 363 11/26 a 46 342 455 357 AVG 46 396 537 400 STDS 3 120 66 55 MIN 41 231 455 325 MAX 52 568 687 502 MEDIAN 45 344 517 379 RUN 6 - CONTROL 35/65, TEST 35/65 solubilized - TOC DATA (mg/L) DAY DATE Control Feed Test Feed Control ATAD Test ATAD 1 10/02 a 60 186 792 761 P 112 417 1124 828 2 12/03 a 56 202 1685 848 P 94 319 1052 746 3 12/04 a 61 186 1205 1960 P 102 300 1108 887 4 12/05 a 64 200 1690 1105 P 114 338 1687 894 5 12/06 a 50 163 1693 1023 P 79 430 1071 1055 6 12/07 a 60 241 888 961 P 100 438 1246 1052 AVG STDS MIN MAX MEDIAN 79 285 1270 1010 24 103 332 322 50 163 792 746 114 438 1693 1960 72 271 1165 928 H - 4 I60 APPENDIX J: FORMULAS & SAMPLE CALCULATIONS J-1 \(a\ TOTAL SOLIDS T S = (™™dried sampie)-(?n™dJ mg N o t e . 1 0000mg/L=10g/L=l%TS V ° l u m e sample L SLUDGE VOLUMES FOR FEED RATIOS L 0 = volume of sludge remaining from previous day gJL = consistency of sludge remaining L x = volume of primary sludge g/L = consistency of primary sludge L 2 = volume of secondary sludge g2/L = consistency of secondary sludge L w = volume of distilled water control feed tank: o 1 test feed tank: ^y^jL) = go (L^igJL) = gx - (mix ratio, ie. ||) = g2 required 2 = L2 required g2IL *f 8ILtes,> 8ILcon»oi g0+gl+g2 j T = Ltotai required 8ILlcontrol ~l-total- ( L o + L i + L i ) = K required Note: if g/L^ < g/LaM„ib then g/L^, was used and L w was calculated for control feed tank. J-2 TOTAL SOLIDS DESTRUCTION % destruction = TSf^~ TSATAD X L 0 Q % TSfeed TSf . + TS, . + TSf . where for day i: avg TSfeed = f " ^ ^ ^ATAD ^ATAD, QUATTRO PRO EQUATIONS _ Ex,. A V G = x = - n STDS = o = E(x-s,) M n-l MEDIAN = 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 t-Test: Paired Two-Sample for Means RUN 1 T E M P E R A T U R E C O N T R O L T E S T RUN 4 T E M P E R A T U R E C O N T R O L T E S T Mean 49.075 46.6 Mean 44.158333 42.076667 Variance 0.7529545 1.0145455 Variance 0.7244697 0.8167152 Observations 12 12 Observations 12 12 Pearson Correlation 0.992283 Pearson Correlation 0.9102993 Pooled Variance 0.88375 Pooled Variance 0.7705924 Hypothesized Mean Difference 0 Hypothesized Mean Difference 0 df 11 df 11 t 47.228936 t 19.220348 P(T<=t) one-tail 2.354E-14 P(T<=t) one-tail 4.092E-10 t Critical one-tail 1.7958848 t Critical one-tail 1.7958848 P(T<=t) two-tail 4.696E-14 P(T<=t) two-tail 8.184E-10 t Critical two-tail 2.2009852 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means t-Test: Paired Two-Sample for Means RUN 2 T E M P E R A T U R E C O N T R O L T E S T RUN 5 T E M P E R A T U R E C O N T R O L T E S T Mean 48.791667 44.541667 Mean 44.166667 43.125 Variance 1.497197 0.2317424 Variance 1.1787879 2.3493182 Observations 12 12 Observations 12 12 Pearson Correlation 0.7568857 Pearson Correlation 0.972932 Pooled Variance 0.8644697 Pooled Variance 1.764053 Hypothesized Mean Difference 0 Hypothesized Mean Difference 0 df 11 df 11 t 16.089631 t 6.7015787 P(T<=t) one-tail 2.718E-09 P(T<=t) one-tail 1.684E-05 t Critical one-tail 1.7958848 t Critical one-tail 1.7958848 P(T<=t) two-tail 5.436E-09 P(T<=t) two-tail 3.369E-05 t Critical two-tail 2.2009852 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means t-Test: Paired Two-Sample for Means RUN 3 T E M P E R A T U R E C O N T R O L T E S T RUN 6 T E M P E R A T U R E C O N T R O L T E S T Mean 45.008333 43.858333 Mean 44.1 42.775 Variance 1.4935606 0.4517424 Variance 0.5363636 0.3802273 Observations 12 12 Observations 12 12 Pearson Correlation 0.8349524 Pearson Correlation 0.7830791 Pooled Variance 0.9726515 Pooled Variance 0.4582955 Hypothesized Mean Difference 0 Hypothesized Mean Difference 0 df 11 df 11 t 5.2598108 t 10.032358 P(T<=t) one-tail 0.0001342 P(T<=t) one-tail 3.579E-07 t Critical one-tail 1.7958848 t Critical one-tail 1.7958848 P(T<=t) two-tail 0.0002685 P(T<=t) two-tail 7.158E-07 t Critical two-tail 2.2009852 t Critical two-tail 2.2009852 Note: if |t| > t critical, a significant difference exists between means K - 2 T-Test Results for ATAD ORP (5% significance) t-Test: Paired Two-Sample for Means RUN 1 ORP C O N T R O L T E S T Mean -242.66667 -318.75 Variance 14.606061 43.659091 Observations 12 12 Pearson Correlation 0.6516014 Pooled Variance 29.132576 Hypothesized Mean Difference 0 df 11 t 52.340668 P(T<=t) one-tail 7.661 E-15 t Critical one-tail 1.7958848 P(T<=t) two-tail 1.521E-14 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means RUN 2 ORP C O N T R O L T E S T Mean -254.75 -373.75 Variance 35.295455 42.386364 Observations 12 12 Pearson Correlation 0.2708793 Pooled Variance 38.840909 Hypothesized Mean Difference 0 df 11 t 54.73204 P(T<=t) one-tail 4.663E-15 t Critical one-tail 1.7958848 P(T<=t) two-tail 9.326E-15 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means RUN 3 ORP C O N T R O L T E S T Mean -261.91667 -393.33333 Variance 139.7197 21.69697 Observations 12 12 Pearson Correlation 0.6098141 Pooled Variance 80.708333 Hypothesized Mean Difference 0 df 11 t 46.888408 P(T<=t) one-tail 2.542E-14 t Critical one-tail 1.7958848 P(T<=t) two-tail 5.085E-14 t Critical two-tail 2.2009852 Note: if |t| > t critical, a significant difference exists between means t-Test: Paired Two-Sample for Means RUN 4 ORP C O N T R O L T E S T Mean -274.41667 -421.33333 Variance 126.44697 8.2424242 Observations 12 12 Pearson Correlation 0.2346629 Pooled Variance 67.344697 Hypothesized Mean Difference 0 df 11 t 46.548846 P(T<=t) one-tail 2.753E-14 t Critical one-tail 1.7958848 P(T<=t) two-tail 5.507E-14 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means RUN 5 ORP C O N T R O L T E S T Mean -330.41667 -282.83333 Variance 694.08333 15638.515 Observations 12 12 Pearson Correlation 0.2723413 Pooled Variance 8166.2992 Hypothesized Mean Difference 0 df 11 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 t-Test: Paired Two-Sample for Means RUN 6 ORP C O N T R O L T E S T Mean -354.41667 -433.25 Variance 134.08333 47.840909 Observations 12 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 K - 3 T-Test Results for VFA Levels in Sludge Feed (5% significance) t-Test: Paired Two-Sample for Means RUN 1 F E E D T O T A L V F A C O N T R O L T E S T 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 290.90647 274.08419 651.33341 694.99115 12 12 0.7564154 673.16228 0 11 3.2152984 0.0041138 1.7958848 0.0082276 2.2009852 t-Test: Paired Two-Sample for Means RUN 4 F E E D T O T A L V F A C O N T R O L T E S T 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 181.76775 7.5846389 1561.5804 168.69527 12 12 0.2295492 865.13784 0 11 15.607317 3.75E-09 1.7958848 7.499E-09 2.2009852 t-Test: Paired Two-Sample for Means RUN 2 F E E D T O T A L V F A C O N T R O L T E S T 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 212.71006 269.2175 761.31298 6463.4023 12 12 0.6128691 3612.3576 0 11 -2.9161821 0.0070165 1.7958848 0.014033 2.2009852 t-Test: Paired Two-Sample for Means RUN 5 F E E D T O T A L V F A C O N T R O L T E S T 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 3.0578333 140.72901 1.6109287 6067.9746 12 12 -0.4810779 3034.7928 0 11 -6.0740338 4.014E-05 1.7958848 8.029E-05 2.2009852 t-Test: Paired Two-Sample for Means RUN 3 F E E D T O T A L V F A C O N T R O L T E S T 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 169.48767 133.70211 2762.1445 1957.857 12 12 0.4631107 2360.0008 0 11 2.447162 0.0162043 1.7958848 0.0324085 2.2009852 t-Test: Paired Two-Sample for Means RUN 6 F E E D T O T A L V F A C O N T R O L T E S T 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 23.195639 115.33892 88.046499 4972.6411 12 12 0.5915625 2530.3438 0 11 -4.8802527 0.0002433 1.7958848 0.0004867 2.2009852 NOTE: if |t| > t critical, a significant difference exists between means K - 4 16? T-Test Results for VFA Levels in ATAD (5% significance) t-Test: Paired Two-Sample for Means t-Test: Paired Two-Sample for Means RUN 1 A T A D T O T A L V F A C O N T R O L T E S T RUN 4 A T A D T O T A L V F A C O N T R O L T E S T Mean 148.05689 163.53594 Mean 203.48983 809.90064 Variance 232.6638 189.182 Variance 1017.215 13489.478 Observations 12 12 Observations 12 12 Pearson Correlation 0.1244804 Pearson Correlation 0.4739458 Pooled Variance 210.9229 Pooled Variance 7253.3465 Hypothesized Mean Difference 0 Hypothesized Mean Difference 0 df 11 df 11 t -2.7890795 t -20.033246 P(T<=t) one-tail 0.0088078 P(T<=t) one-tail 2.625E-10 t Critical one-tail 1.7958848 t Critical one-tail 1.7958848 P(T<=t) two-tail 0.0176155 P(T<=t) two-tail 5.25E-10 t Critical two-tail 2.2009852 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means t-Test: Paired Two-Sample for Means RUN 2 A T A D T O T A L V F A C O N T R O L T E S T RUN 5 A T A D T O T A L V F A C O N T R O L T E S T Mean' 250.73333 565.04675 Mean 30.503889 4.1485 Variance 979.91615 2651.6129 Variance 987.90338 3.9078355 Observations 12 12 Observations 12 12 Pearson Correlation 0.2840417 Pearson Correlation 0.4812847 Pooled Variance 1815.7645 Pooled Variance 495.90561 Hypothesized Mean Difference 0 Hypothesized Mean Difference 0 df 11 df 11 t -20.893141 t 2.9905515 P(T<=t) one-tail 1.671E-10 P(T<=t) one-tail 0.0061428 t Critical one-tail 1.7958848 t Critical one-tail 1.7958848 P(T<=t) two-tail 3.343E-10 P(T<=t) two-tail 0.0122856 t Critical two-tail 2.2009852 t Critical two-tail 2.2009852 t-Test: Paired Two-Sample for Means t-Test: Paired Two-Sample.for Means RUN 3 A T A D T O T A L V F A C O N T R O L T E S T RUN 6 A T A D T O T A L V F A C O N T R O L T E S T Mean 205.05625 434.42964 Mean 391.91654 478.20478 Variance 523.51304 2387.644 Variance 7320.7628 21268.485 Observations 12 12 Observations 12 12 Pearson Correlation -0.0101268 Pearson Correlation 0.3553911 Pooled Variance 1455.5785 Pooled Variance 14294.624 Hypothesized Mean Difference 0 Hypothesized Mean Difference 0 df 11 df 11 t -14.669602 t -2.1285699 P(T<=t) one-tail 7.202E-09 P(T<=t) one-tail 0.0283601 t Critical one-tail 1.7958848 t Critical one-tail 1.7958848 P(T<=t) two-tail 1.44E-08 P(T<=t) two-tail 0.0567202 t Critical two-tail 2.2009852 t Critical two-tail 2.2009852 NOTE: if |t| > t critical, a significant difference exists between means K - 5

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