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Effect of hydraulic retention time on landfill leachate and gas characteristics Munasinghe, Ranjani 1997

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E F F E C T OF H Y D R A U L I C R E T E N T I O N TIME O N L A N D F I L L L E A C H A T E A N D GAS CHARACTERISTICS by Ranjani Munasinghe B.Sc. (Hons), Peradeniya, Sri Lanka; M . E n g . , Bangkok, Thailand  A THESIS SUBMITTED IN P A R T I A L F U L F I L L M E N T OF T H E REQUIREMENTS FOR T H E D E G R E E OF D O C T O R OF P H I L O S O P H Y  in T H E F A C U L T Y OF G R A D U A T E STUDIES CIVIL ENGINEERING  We accept this thesis as conforming to the required standard  T H E U N I V E R S I T Y OF BRITISH C O L U M B I A August 1997 © Ranjani Munasinghe, 1997  In presenting this thesis i n partial fulfilment of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the L i b r a r y 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 C i v i l Engineering T h e University of B r i t i s h C o l u m b i a Vancouver, C a n a d a  Date:  A.^.g^....M..>.(^'?  Abstract  Previous field studies carried out in order to characterize leachate in Vancouver, B . C . landfills show an effect of water input patterns on leachate characteristics. With high rainfall into the landfills, high volatile fatty acid (VFA) concentrations appear in leachate. It is postulated that with high rainfall there is a reduction in hydraulic retention time (HRT) which results in a reduction in the conversion of V F A to CH4 and CC>2- Coincidence of peak infiltration rates with high dissolved organic carbon concentrations greatly increases the pollutant loadings to the treatment plants. The objective of the study was to investigate the effects of H R T on landfill leachate and gas characteristics. HRTs from 3 to 200 days were assigned to eighteen lab scale lysimeters during four experimental phases in which the H R T was changed by changing the infiltration rates through the lysimeters. A relationship was established between H R T and infiltration rate in refuse columns and tested using tracer studies. For unsaturated landfills; S HRT  =  — Q  Where; S = Volumetric water holding capacity of the solid waste in the landfill X Volume of the solid waste in the landfill (L ) 3  Q = Flow rate through the landfill ( L T ) 3  _ 1  Percent C H 4 concentration in gas decreased with increasing H R T up to 60 days.  ii  Lower H R T s showed higher CH4 productions and increase i n CH4 concentration indicating enhanced methanogenesis. H i g h gas producing columns increased their p H w i t h time from values less than 5.5 irrespective of the changes i n H R T . Decrease in H R T helped the columns with low gas production and p H less than 5.3 to increase their p H which is favorable for methanogenesis. W h e n H R T was decreased i n columns w i t h high gas production and p H higher than 5.8, a slight decrease i n p H was observed w i t h a substantial decrease in CO2 concentration i n gas, but no detrimental effect on gas production was observed. Gas production itself helps i n developing favorable conditions for biological degradation; it increases p H , produces alkalinity when V F A s are consumed, responds favorably to changes in H R T , reduces inhibitive concentrations of V F A s and other organics and inorganics i n the m i croenvironments. T h e amount of total carbon released to the environment is highly dependent on gas production. H i g h gas producing columns released 50% more carbon than low gas producing columns. Continuous mobilization of zinc and iron occurred throughout the experiment. Zinc concentrations showed inconsistent correlation to either p H or methane production rate. Correlation of iron concentrations to p H and CH4 production rate showed dependence on H R T and CH4 production stage of the column. T h e high V F A concentrations observed i n field studies are not, based on this study likely to be due to the failure of methanogenesis because of high water inputs contrary to the original hypothesis. D u r i n g phase I under similar H R T conditions, there was considerable variability i n methane production from the lysimeters that could not be explained.  iii  Table of Contents  Abstract  ii  List of Figures  x  List of Tables  xx  nomenclature  xxii  Acknowledgment  xxiii  1  Introduction  1  2  Background and Literature Review  4  2.1  Introduction  4  2.2  Landfill Characteristics  4  2.3  Leachate Production  4  2.3.1  Hydrological Balance in Landfills  5  2.3.2  Field Capacity  7  2.3.3  Moisture Flow Through the Refuse  7  2.4  2.5  Landfill Gas Production and Characteristics  10  2.4.1  Decomposition of Refuse  10  Factors Affecting Waste Decomposition  12  2.5.1  Oxygen  12  2.5.2  Hydrogen  14  iv  2.5.3  p H and Alkalinity  14  2.5.4  Sulfate  15  2.5.5  Nutrients  15  2.5.6  Inhibitors  16  2.5.7  Temperature  17  2.5.8  M o i s t u r e / W a t e r Content  18  2.6  Landfill Leachate Characteristics  20  2.7  Change i n Landfill Gas and Leachate Characteristics w i t h T i m e  20  2.8  Effects of Infiltration of Water through Refuse  26  2.9  Effects of Rainfall Pattern on Landfill Leachate and Gas Characteristics .  26  2.10 Landfill Stabilization  30  2.11 H y d r a u l i c Retention T i m e of Landfills  30  2.12 Present Trends i n Landfill Management and T i m i n g of the Research . . .  33  2.13 Summary  34  3  Objectives  36  4  Experimental Methods and Analytical Procedures  38  4.1  E x p e r i m e n t a l Set-up  38  4.1.1  Construction of Lysimeters  38  4.1.2  F i l l i n g of Refuse i n the Columns  40  4.1.3  Preparation of Columns for the Study  43  4.2  Selection of H R T s for the Study  43  4.3  Methodology-Phase I  46  4.4  Methodology-Phase II  46  4.5  Methodology-Phase III  48  4.6  Methodology-Phase I V  49 v  4.7  Tracer Experiments  50  4.8  Analytical Procedures  51  4.8.1  51  4.9  5  P  H  4.8.2  Volatile Fatty Acids (VFAs)  51  4.8.3  Chemical Oxygen Demand (COD)  52  4.8.4  Total Organic Carbon (TOC) and Inorganic Carbon (IC)  52  4.8.5  Alkalinity  52  4.8.6  Specific Conductance  53  4.8.7  Solids  53  4.8.8  Nitrogen  53  4.8.9  Metals  54  4.8.10 Chloride  54  4.8.11 Gas Analysis  55  Statistics  55  Results and Discussion  56  5.1  Introduction  56  5.2  Hydraulic Retention Time for Landfills  58  5.2.1  61  5.3  Tracer Experiments  General Characteristics of Landfill Gas (Phase I)  70  5.3.1  96  Methane potential of the Refuse Columns  5.4  Effect of H R T on Landfill Gas Characteristics (Phases II, III and IV)  5.5  General Characteristics of Leachate (Phase I)  107  5.6  Effect of H R T on Landfill Leachate (Phase II and III)  107  5.6.1  pH  108  5.6.2  Volatile Fatty Acids (VFA)  113  vi  . .  101  6  5.6.3  Chemical Oxygen Demand (COD)  126  5.6.4  Total Organic Carbon (TOC) and Inorganic Carbon (IC)  128  5.6.5  Alkalinity  132  5.6.6  Specific Conductance  135  5.6.7  Total Solids  137  5.6.8  Nitrogen (NH  5.6.9  Iron  143  5.6.10 Zinc  149  5.6.11 Sodium  153  5.6.12 Chloride  155  5.7  Pollutant Release to the Environment from the Lysimeters  157  5.8  Micro-environments  163  5.9  Carbon Released to the Environment  164  5.9.1  Carbon in Leachate  165  5.9.2  Carbon in Gas  166  3  - N, T K N )  139  5.10 General Overview  191  5.11 Potential Applications of Findings  199  Conclusions and Future Work  209  6.1  Conclusions  209  6.2  Recommendations for Future Work  211  Bibliography  212  Appendices  219  A  Calculation of 00% produced and Total Gas Production  219  A.l  220  C0  2  Produced vii  A.1.1  For Samples with Low Dissolved Solids - Method 1  220  A. 1.2  Sample calculation  221  A.1.3  Total Gas Produced Calculated from Method 1  222  A. 1.4  For Samples with High Dissolved Solids - Method 2  223  A. 1.5  Sample Calculation  224  A. 1.6  Total Gas Produced Calculated from Method 2  225  B  Regression Plots for Iron and p H  230  C  Regression Plots for Iron and Methane Production Rate  239  D Regression Plots for Zinc and p H  248  E  Regression Plots for Zinc and Methane Production Rate  257  F  Leachate Characteristics Data  266  F.l  pH  266  F.2  Volatile Fatty Acids  267  F.3  Distribution of V F A types  268  F.4  Chemical Oxygen Demand  274  F.5  Total Organic Carbon  275  F.6  Inorganic Carbon  276  F.7  Alkalinity  277  F.8  Specific Conductance  278  F.9  Total Solids  279  F.10 T K N  280  F . l l Ammonia Nitrogen  281  F.12 Zinc  282  viii  F.13 Iron  283  F.14 Sodium  284  F. 15 Chlorides  285  G Gas Characteristics Data G. l  286  Composition of Gas  286  G.2 Gas Production  291  ix  List of Figures  2.1  Schematic of the General Hydrological Balance in a Completed Sanitary Landfill  2.2  6  Substrates and Major Bacterial Groups Involved in the Methane Generating Ecosystem  11  2.3  Major Abiotic Factors Affecting the Methane-generating Ecosystem  . .  2.4  Illustration of Developments in Gas and Leachate Composition in a Landfill Cell  2.5  13  24  Summary of Observed Trends in Refuse Decomposition with Leachate Recycle  25  2.6  Stimulus-Response Techniques Commonly used to Study Flow in Reactors 32  4.1  Schematic of the Experimental Set-up  39  4.2  Schematic of a Wet Gas Meter  43  5.1  Tracer Response Curve for HRT=18 days  66  5.2  Tracer Response Curve for HRT=35 days  66  5.3  Tracer Response Curve for HRT=60 days  67  5.4  Tracer Response Curve for HRT=120 days  67  5.5  Tracer Response Curve for HRT=200 days  68  5.6  Comparison of Observed HRTs  68  5.7  Tracer Response Curve for column 16  69  5.8  Tracer Response Curves for Columns 7 and 10 at Different Stages of Decomposition  69 x  5.9  Methane Production Rate in Columns 1-3  72  5.10  Methane Production Rate in Columns 4-6  73  5.11  Methane Production Rate in Columns 7-9  74  5.12  Methane Production Rate in Columns 10-12  75  5.13  Methane Production Rate in Columns 13-15  76  5.14  Methane Production Rate in Columns 16-18  77  5.15  Cumulative Methane Production in Columns 1-3  78  5.16  Cumulative Methane Production in Columns 4-6  78  5.17  Cumulative Methane Production in Columns 7-9  79  5.18  Cumulative Methane Production in Columns 10-12  79  5.19  Cumulative Methane Production in Columns 13-15  80  5.20  Cumulative Methane Production in Columns 16-18  80  5.21  Composition of Gas in Column 1  81  5.22  Composition of Gas in Column 2  81  5.23  Composition of Gas in Column 3  82  5.24  Composition of Gas in Column 4  82  5.25  Composition of Gas in Column 5  83  5.26  Composition of Gas in Column 6  83  5.27  Composition of Gas in Column 7  84  5.28  Composition of Gas in Column 8  84  5.29  Composition of Gas in Column 9  85  5.30  Composition of Gas in Column 10  85  5.31  Composition of Gas in Column 11  86  5.32  Composition of Gas in Column 12  86  5.33  Composition of Gas in Column 13  87  5.34  Composition of Gas in Column 14  87  xi  5.35  Composition of Gas in Column 15  88  5.36  Composition of Gas in Column 16  88  5.37  Composition of Gas in Column 17  89  5.38  Composition of Gas in Column 18  89  5.39  Gas Production Rates in Columns 1-3  90  5.40  Gas Production Rates in Columns 4-6  91  5.41  Gas Production Rates in Columns 7-9  92  5.42  Gas Production Rates in Columns 10-12  93  5.43  Gas Production Rates in Columns 13-15  94  5.44  Gas Production Rates in Columns 16-18  95  5.45  Effect of H R T on CH  5.46  Comparison of Cumulative CH4 Production of Columns 2, 5 and 6 . . .  105  5.47  Comparison of Cumulative CH4 Production of Columns 15 and 1 . . . .  106  5.48  Comparison of Cumulative CH4 Production of Columns 12 and 13 . . .  106  5.49  Change in pH in Columns 11, 12 and 14  110  5.50  Change in pH in Columns 2, 7, 10, 13, 16 and 18  Ill  5.51  Change in pH in Columns 1, 3 and 4  Ill  5.52  Change in pH in Columns 5, 8 and 9  112  5.53  Change in pH in Columns 6, 15 and 17  112  5.54  Change in V F A in Columns 1-6  115  5.55  Change in V F A in Columns 7-12  116  5.56  Change in V F A in Columns 13-18  116  5.57  Distribution of VFAs in Column 1  117  5.58  Distribution of VFAs in Column 2  117  5.59  Distribution of VFAs in Column 3  118  5.60  Distribution of VFAs in Column 4  118  4  Concentration in Landfill Gas  xii  105  5.61  Distribution of VFAs in Column 5  119  5.62  Distribution of VFAs in Column 6  119  5.63  Distribution of VFAs in Column 7  120  5.64  Distribution of VFAs in Column 8  120  5.65  Distribution of VFAs in Column 9  121  5.66  Distribution of VFAs in Column 10  121  5.67  Distribution of VFAs in Column 11  122  5.68  Distribution of VFAs in Column 12  122  5.69  Distribution of VFAs in Column 13  123  5.70  Distribution of VFAs in Column 14  123  5.71  Distribution of VFAs in Column 15  124  5.72  Distribution of VFAs in Column 16  124  5.73  Distribution of VFAs in Column 17  125  5.74  Distribution of VFAs in Column 18  125  5.75  Change in C O D in Columns 1-6  126  5.76  Change in C O D in Columns 7-12  127  5.77  Change in C O D in Columns 13-18  127  5.78  Change in T O C in Columns 1-6  129  5.79  Change in T O C in Columns 7-12  129  5.80  Change in T O C in Columns 13-18  130  5.81  Change in IC in Columns 1-6  130  5.82  Change in IC in Columns 7-12  131  5.83  Change in IC in Columns 13-18  131  5.84  Change in Alkalinity in Columns 1-6  133  5.85  Change in Alkalinity in Columns 7-12  133  5.86  Change in Alkalinity in Columns 13-18  134  xiii  5.87  HRT, pH and Alkalinity of the Leachate at Steady State  134  5.88  Change in Specific Conductance in Columns 1-6  135  5.89  Change in Specific Conductance in Columns 7-12  136  5.90  Change in Specific Conductance in Columns 13-18  136  5.91  Change in Total Solids in Columns 1-6  137  5.92  Change in Total Solids in Columns 7-12  138  5.93  Change in Total Solids in Columns 13-18  138  5.94  Change in T K N in Columns 1-6  140  5.95  Change in T K N in Columns 7-12  140  5.96  Change in T K N in Columns 13-18  141  5.97  Change in Ammonia Nitrogen in Columns 1-6  141  5.98  Change in Ammonia Nitrogen in Columns 7-12  142  5.99  Change in Ammonia Nitrogen in Columns 13-18  142  5.100 Change in Iron in Columns 1-6  147  5.101 Change in Iron in Columns 7-12  148  5.102 Change in Iron in Columns 13-18  148  5.103 Change in Zinc in Columns 1-6  151  5.104 Change in Zinc in Columns 7-12  152  5.105 Change in Zinc in Columns 13-18  152  5.106 Change in Sodium in Columns 1-6  153  5.107 Change in Sodium in Columns 7-12  154  5.108 Change in Sodium in Columns 13-18  154  5.109 Change in Chloride in Columns 1-6  155  5.110 Change in Chloride in Columns 7-12  156  5.111 Change in Chloride in Columns 13-18  156  xiv  5.112  Comparison of C O D with the C O D Prediction Curve by Reitzal et al., 1992  161  5.113 Comparison of Chloride with the Chloride Prediction Curve by Reitzal et al., 1992 5.114  5.115  162  Comparison of NHz — N with the NHs — N Prediction Curve by Reitzal et al., 1992  162  Carbon Released to the Environment from Column 1  172  5.116 Carbon Released to the Environment from Column 2 .  173  5.117 Carbon Released to the Environment from Column 3  174  5.118  Carbon Released to the Environment from Column 4  175  5.119 Carbon Released to the Environment from Column 5  176  5.120 Carbon Released to the Environment from Column 6  177  5.121  Carbon Released to the Environment from Column 7  178  5.122  Carbon Released to the Environment from Column 8  179  5.123  Carbon Released to the Environment from Column 9  180  5.124  Carbon Released to the Environment from Column 10  181  5.125 Carbon Released to the Environment from Column 11  182  5.126  Carbon Released to the Environment from Column 12  183  5.127 Carbon Released to the Environment from Column 13  184  5.128  Carbon Released to the Environment from Column 14  185  5.129 Carbon Released to the Environment from Column 15  186  5.130 Carbon Released to the Environment from Column 16  187  5.131  Carbon Released to the Environment from Column 17  188  5.132  Carbon Released to the Environment from Column 18  189  5.133 Carbon Released to the Environment in Relation to the CH^ Production  xv  190  A.l  Comparison of Measured and Calculated Gas Production Rates for C o l umn 1  A.2  226  Comparison of Measured and Calculated Gas Production Rates for C o l umn 2  A.3  226  Comparison of Measured and Calculated Gas Production Rates for C o l umn 3  A.4  227  Comparison of Measured and Calculated Gas Production Rates for C o l umn 4  A.5  227  Comparison of Measured and Calculated Gas Production Rates for C o l umn 12  A.6  228  Comparison of Measured and Calculated Gas P r o d u c t i o n Rates for C o l u m n 14  A.7  228  Comparison of Measured and Calculated Gas Production Rates for C o l umn 16  A. 8  229  Comparison of Measured and Calculated Gas Production Rates for C o l umn 18  229  B. 9  Iron V s p H for C o l u m n 1  230  B.10  Iron V s p H for C o l u m n 2  230  B.ll  Iron V s p H for C o l u m n 3  231  B.12  Iron V s p i I for C o l u m n 4  231  B.13  Iron V s p H for C o l u m n 5  232  B.14  Iron V s p H for C o l u m n 6  232  B.15  Iron V s p H for C o l u m n 7  233  B.16  Iron V s p H for C o l u m n 8  233  B.17  Iron V s p H for C o l u m n 9  234  xvi  B.18  Iron Vs pH for Column 10  234  B.19  Iron Vs pH for Column 11  235  B.20  Iron Vs pi I for Column 12  235  B.21  Iron Vs pH for Column 13  236  B.22  Iron Vs pi I for Column 14  B.23  Iron Vs pH for Column 15  237  B.24  Iron Vs pH for Column 16  237  B.25  Iron Vs pH for Column 17  238  B. 26  Iron Vs pH for Column 18  238  C. 27  Iron Vs Methane Production Rate for Column 1  239  C.28  Iron Vs Methane Production Rate for Column 2  239  C.29  Iron Vs Methane Production Rate for Column 3  240  C.30  Iron Vs Methane Production Rate for Column 4  240  C.31  Iron Vs Methane Production Rate for Column 5  241  C.32  Iron Vs Methane Production Rate for Column 6  241  C.33  Iron Vs Methane Production Rate for Column 7  242  C.34  Iron Vs Methane Production Rate for Column 8  242  C.35  Iron Vs Methane Production Rate for Column 9  243  C.36  Iron Vs Methane Production Rate for Column 10  243  C.37 Iron Vs Methane Production Rate for Column 11  244  C.38  Iron Vs Methane Production Rate for Column 12  244  C.39 Iron Vs Methane Production Rate for Column 13  245  C.40 Iron Vs Methane Production Rate for Column 14  245  C.41  Iron Vs Methane Production Rate for Column 15  246  C.42  Iron Vs Methane Production Rate for Column 16  246  . ,  236  xvii  C.43  Iron Vs Methane Production Rate for Column 17  247  C. 44  Iron Vs Methane Production Rate for Column 18  247  D. 45  Zinc Vs pi I for Column 1  248  D.46  Zinc Vs pH for Column 2  248  D.47  Zinc Vs pH for Column 3  249  D.48  Zinc Vs pi I for Column 4  249  D.49  Zinc Vs pi I for Column 5  250  D.50  Zinc Vs pH for Column 6  250  D.51  Zinc Vs pi I for Column 7  251  D.52  Zinc Vs pH for Column 8  251  D.53  Zinc Vs pH for Column 9  252  D.54  Zinc Vs pH for Column 10  252  D.55  Zinc Vs pi I for Column 11  253  D.56  Zinc Vs pH for Column 12  253  D.57  Zinc Vs pH for Column 13  254  D.58  Zinc Vs pH for Column 14  254  D.59  Zinc Vs pH for Column 15  255  D.60  Zinc Vs pli for Column 16  255  D.61  Zinc Vs pH for Column 17  256  D. 62  Zinc Vs pi I for Column 18  256  E. 63  Zinc Vs Methane Production Rate for Column 1  257  E.64  Zinc Vs Methane Production Rate for Column 2  257  E.65  Zinc Vs Methane Production Rate for Column 3  258  E.66  Zinc Vs Methane Production Rate for Column 4  258  E.67  Zinc Vs Methane Production Rate for Column 5  259  xviii  E.68  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 6  259  E.69  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 7  260  E.70  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 8  260  E.71  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 9  261  E.72  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 10  261  E.73  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 11  262  E.74  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 12  262  E.75  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 13  263  E.76  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 14  263  E.77  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 15  264  E.78  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 16  264  E.79  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 17  265  E.80  Zinc V s Methane P r o d u c t i o n Rate for C o l u m n 18  265  xix  List of Tables  2.1  Field Capacities for Unprocessed Refuse  8  2.2  Toxic Concentrations of Heavy Metals in Anaerobic Waste Treatment  17  2.3  Typical Leachate Constituent Concentrations for Landfills  21  2.4  Characteristics of Landfills with High Organic Carbon during High Water Input  28  4.1  Composition of Refuse  40  4.2  Characteristics of the Prepared Columns and Feed Water  44  4.3  Experimental Design for Phase II  47  4.4  Experimental Design for Phase III  48  4.5  Summary of Experimental Conditions During the Research  49  4.6  LiCl Mass used in Tracer Studies  50  5.1  Moisture Sorbed and S of the Columns  60  5.2  t, a  62  5.3  Comparison of Predicted and Observed HRTs  64  5.4  Comparison of CH4 Produced from the Columns  99  5.5  Comparison of CH  5.6  Comparison of CH± concentration before Phase III and after Phase IV .  5.7  Summary of Correlation Analysis of Iron Vs pH and CH4 Production Ratel46  5.8  Summary of Correlation Analysis of Zinc Vs pH and CH4 Production Rate 150  5.9  Mass of V F A , C O D , T O C and Alkalinity Leached during Phases I and II 158  5.10  Mass of Conductivity, Total Solids, T K N and NH -  2  and Percentage of Mass of Tracer Recovered  4  Yields and Annual Production Rates  2  xx  N Leached . . . .  100 103  159  5.11  Mass of Iron, Zinc and Sodium Leached  160  5.12  Summary of Carbon Releases from the Landfill  169  5.13  Effect of H R T on pH and Iron Concentrations  196  5.14  Effect of H R T on V F A , C O D , T O C , TS, Na and Specific Conductance .  197  5.15  Effect of H R T on T K N , NH  198  3  - N and Zinc  xxi  nomenclature  Symbol  Description  CH  Methane  C0  Carbon Dioxide  COD  Chemical Oxygen Demand  DLC  Demolition Landclearing and Construction  HRT  Hydraulic Retention Time  IC  Inorganic Carbon  MSW  Municipal Solid Waste  n  Number of observations  4  2  Nitrogen  N  2  NH  Z  o  -N  2  Ammonia Nitrogen Oxygen  ORP  Oxidation Reduction Potential  R  Coefficient of Determination (Square of Correlation Coefficient)  SD  Standard Deviation  SSE  Sum of Squares due to Error  SSR .  Sum of Squares due to Regression  TKN  Total Kjeldahl Nitrogen  TOC  Total Organic Carbon  TS  Total Solids  TSS  Total Suspended Solids  VFA  Volatile Fatty Acid  2  xxii  Acknowledgment  I would like to express my sincere gratitude to my supervisor Prof. J.W. Atwater for his constant supervision, guidance and encouragement throughout this research. I would like to thank my supervisory committee, Drs. Donald S. Mavinic, Kenneth J. Hall and Sheldon Duff for their guidance and valuable comments and suggestions throughout this research. I also wish to thank Dr. Richard M.R. Branion for his valuable input on tracer studies. I am also grateful to Susan Harper, Paula Parkinson, Jufang Zhou and Guy Kirsch for their assistance during the setting up the experiment and analytical work. Also thanks are due to Martin Donat, John Brereton, Heather Artherton, Rhiannon Johnson and Ron Macdonald for their help in collection and filling up the refuse in the columns; to the residents of U B C student family housing who helped me in collection of food waste; Vancouver Transfer Station at Kent Avenue and Lions Gate Sewage Treatment Plant staff for their support. I am also grateful to all my family, friends and Sarah Dench for their support and encouragement. No words of gratitude could repay the moral support, encouragement and sacrifice by my husband Kamal. I would like to dedicate this work to my little girl Dinushi and to Kamal.  "Dinushi, now that my thesis is finished, can I join your Earthsavers Club?"  xxiii  Chapter 1  Introduction  Sanitary landfills have been a traditional means of solid waste disposal in most parts of the world including North America. Today, the environmental impacts of landfilling are well recognized and at most sanitary landfills, measures are taken to control these. In terms of early planning and designing of sanitary landfills, leachate treatment plants and gas disposal/treatment facilities, characterization of leachate and gas has become an absolute necessity. The characterization of landfill leachate is difficult for a number of reasons, the most important of which is the site specific nature of the leaching process.  The climate,  surface hydrology and hydrogeology of the site, all have a large influence on the amount of water entering and leaving a landfill. The amount of water along with the age, mode of site operation and the type of waste disposed of affect the nature and strength of the leachate produced. Also the moisture content of the waste, seasonal variations in infiltration, landfill microbiology, waste compaction, and use and composition of cover material have an influence on the characteristics of the resultant leachate (Robinson et al., 1982). Field studies done on leachate characterization show a relationship of water input patterns and hydraulics of the landfill to leachate strength and mass loading with respect to organic compounds.  In the Port Mann landfill, Vancouver, B . C . and the Premier  landfill, North Vancouver, B . C . , peak organic concentrations coincided with the end of the peak rainfall period and the peak in the calculated leachate discharge flow rate (Jasper  1  Chapter 1. Introduction  2  et al., 1987). Similarly, at the Richmond landfill, Soper and McAlpine (1977) reported peak concentrations occurring with high water inputs. The same trend of peak organic concentrations during high leachate flows is also reported by other researchers (Bull et al. 1983, Rovers and Farquhar, 1973). As a response to new regulations, new landfills are designed to minimize the environmental impact. Leachate production is minimized by controlling the water inflow into the landfill leaving a moisture deficient environment for biodegradation. This will extend the landfill stabilization period. Harris et al. (1994) calculated under these conditions it will take 500 years or more for the landfills in U.K. to stabilize and leachate NH3  — N levels to reduce to dischargeable concentrations. Therefore if environmental  impact from these landfills is to be minimized, liners, leachate and gas collection systems and treatment plants should be designed for over 500 years. More researchers; e.g. Harris et al. (1994) and Wall and Zeiss (1995) are recognizing the importance of introducing water into the landfills. But the observations of the researchers Jasper et al. (1987), Soper and McAlpine (1977), Rovers and Farquhar (1972) and Bull et al. (1983) show a limit in introducing water. Therefore before designing new landfills with moisture inputs, the coincidence of high organic carbon in leachate with water inputs should be properly understood. The objective of this thesis was to determine the effects of hydraulic retention time on landfill leachate and gas characteristics. Past literature (Jasper et al., 1987) suggests that there exists an interrelated effect of hydraulic retention time, rate of infiltration and moisture content on leachate and gas characteristics. To reduce the environmental impact from landfills and to satisfy the legislation requirements concerning aqueous discharges into surface waters, treatment of leachate has become necessary. Coincidence of peak flow rates with peak concentrations greatly increase the mass loadings of pollutants to the treatment plants which will interfere with the treatment performances. Therefore  Chapter 1. Introduction  3  the problem of increasing organic concentrations w i t h increased flow should be addressed before designing landfills and/or treatment plants. Improved knowledge of the characteristics of the leachate and gas w i t h respect to the parameters; hydraulic retention time, infiltration rate and moisture content will help the designers of landfills and leachate treatment plants. Landfill management can be effectively done i f the control parameters can be manipulated to achieve the objectives such as maximizing gas production, maximizing landfill stabilization, minimizing landfill life etc.. T h e literature review (Chapter 2) summarizes background for the study and the parameters that affect landfill leachate and gas characteristics. T h e objectives of this study are given i n Chapter 3. Materials and methods are described i n Chapter 4. Results of the study and the discussion of results are presented i n Chapter 5. Conclusions and the recommendations for the future work are given i n Chapter 6.  Chapter 2  Background and Literature Review  2.1  Introduction  This research focuses on the effects of Hydraulic Retention Time (HRT) on characteristics of landfill gas and leachate. Reviewed in this chapter is the background for the research. Production of landfill leachate and gas is reviewed. Literature dealing with the factors affecting landfill leachate and gas characteristics is presented. The main factor affecting leachate and gas characteristics is decomposition of refuse. A review of biological processes involved in decomposition of refuse and the factors affecting these processes are also presented.  2.2  Landfill Characteristics  Once refuse is deposited in the landfill, physical, chemical and biological processes will take place.  As a result gaseous, dissolved and suspended compounds in the form of  landfill gas and leachate are released. In most landfills, assuming that they receive some organic wastes, the microbial processes will dominate the stabilization of waste and hence govern the generation and composition of landfill gas and leachate.  2.3  Leachate Production  Leachate is water that has percolated through emplaced refuse and, in doing so, has suspended and dissolved constituents.  Thus leachate constituents are a reflection of  4  5  Chapter 2. Background and Literature Review  material in the waste. Refuse, when disposed to landfills receives moisture from different sources.  Moisture at placement and precipitation are major contributors.  With the  input of water into the refuse mass, sorption occurs. Leachate starts to appear before the refuse reaches its field capacity (described in Section 2.3.2) and will increase in flow rate until the landfill reaches its field capacity. The volume of leachate produced depends on volume of water entering and leaving the landfill.  2.3.1  Hydrological Balance in Landfills  Figure 2.1 adapted from Canziani and Cossu (1989) gives an overall summary of the components which make up the hydrological balance of a controlled landfill where; P  = Precipitation  J  = Irrigation or leachate recirculation  R  = Surface runoff  R  e  = Run-on from external areas  E T = Actual evapotranspiration Pi  = Net infiltration through the cover  Pi  = P + J + R - R - ET ±  U  = Water content in soil  s  e  AU  S  U  = Water content in waste  S  = Water added by sludge disposal  b  = Water production if > 0; Water consumption if < 0  w  caused by the biological degradation of organic matter I  = Water from surface water sources  Iq  = Ground water infiltration  L  = Total leachate production  s  Chapter 2. Background and Literature Review  6  Figure 2.1: Schematic of the General Hydrological Balance in a Completed Sanitary Landfill with Leachate Drainage System (adapted from Canziani and Cossu, 1989)  L  = P + S + I + I  LR  —  t  s  G  ± AU + b W  L - Lj  Li = Infiltration into aquifers LR  = Leachate collected by drains  From this it can be seen that only some of the components of the hydrological balance can be influenced. A good description of all the component parts in the hydrological balance (see Figure 2.1) and with details on how to estimate each component is given in Canziani and Cossu (1989). Modern landfill designs are aimed at controlling the amount of water entering the landfills so that the leachate produced is minimized.  Also in most modern landfills  efforts are taken to control ground water inflow as well as to contain the leachate within the landfill.  These measures will decrease the landfill leachate volume decreasing the  Chapter 2.  Background and Literature Review  7  cost of disposal. B u t the long term effects on the environment from the landfill are not addressed (Munasinghe and Atwater, 1996).  2.3.2  Field Capacity  The field capacity is defined as the moisture content above which continuous gravity drainage w i l l occur. Water infiltrating through refuse will be sorbed by the waste until the field capacity is reached.  A n y additional water w i l l infiltrate to the next layer of  refuse. Studies have shown breakthrough of leachate before the refuse mass reaches field capacity (Zeiss and Major, 1993). Moisture content is either calculated on volume basis or weight basis (dry or wet). Moisture contents through out this thesis are calculated on weight basis unless specified. Water percolating through a landfill w i l l be sorbed by the waste until the field capacity is reached. W h e n the infiltration of water exceeds the field capacity movement of water through the waste w i l l occur. F i e l d capacity of refuse depends on many factors. Density, type of refuse (composition, whether processed or not etc.) and the stage of decomposition of the waste (age). Table 2.1 (adapted from Table 8, Holmes, 1980) presents the field capacities for different densities and for wastes of different ages. It can be seen from this table that field capacity (weight basis) decreases w i t h increasing density for raw refuse. Also that field capacity decreases w i t h time.  2.3.3  Moisture Flow Through the Refuse  Hydrologic models similar to the model discussed above i n Section 2.3.1 are useful i n predicting volume of leachate produced over time. B u t when it comes to the designs of leachate collection, bottom liners etc. it is necessary to know the velocity and discharge rate of water through layers of refuse. Also hydraulics of the landfill and the collection system should be known before designing leachate collection and treatment systems.  8  Chapter 2. Background and Literature Review  Type of Waste  Density (wet basis) (kg/m ) 282 523 624 3  Raw Raw Raw Raw mixed with sludge after: a. 4 yrs b. 10 yrs c. 17 yrs  Field Capacity (% volume) (% weight) (on a wet basis) (on a wet basis) 29 101 75 39 37 59  638 814 960  60 49 44  38 40 42  Table 2.1: Field Capacities for Unprocessed Refuse (adapted from Holmes, 1980)  Several researchers have investigated and modeled the flow through the refuse. Demetracopoulos et al. (1986) and Korfiatis et al. (1984) modeled the flow through solid waste landfills assuming the flow is predominantly vertical. Horizontal flow due to inhomogeneities of the landfill material was assumed to be a small fraction of the total flow. The theory of unsaturated flow through porous media was used to develop their model. They found the model to be very sensitive to changes of the physical properties of the porous medium, mostly the hydraulic conductivity. Schroeder et al. (1988) modeled (HELP) vertical moisture flow through compacted municipal waste layers to be Darcian drainage flow through a constant homogeneous medium with constant characteristics over time.  Characteristics of the refuse change  much more than a soil medium due to decomposition and leaching of the material. Khanbilvardi et al. (1995) developed the model Flow Investigation for Landfill Leachate (FILL). This model describes the leachate flow process in a landfill as a two-dimensional unsteady-state moisture flow. All these researchers assumed the landfill to be comparable to a porous medium with constant characteristics. Refuse is a porous medium with characteristics changing  9  Chapter 2. Background and Literature Review  with time due to decomposition and leaching of material.  Refuse sorbs moisture, a  characteristic that none of the researchers (except H E L P model) accounted for in their models. Korfiatis (1984) acknowledged the importance of sorptive characteristics of the refuse but this was not accounted for in his model. Zeiss and Major (1993) observed channeling and flow along wetting curves which produced irregular and more rapid breakthrough times and leakage rates of leachate. In these experiments an infiltration rate of 94.6 mm/hr was used. Channeling is the vertical flow of liquid through channels with cross sectional areas which are substantially less than the cross section of the top layer of waste where infiltration occurs. The constriction of flow into channels through the waste layers in landfills is predicted to significantly reduce breakthrough and flow time from infiltration into the top waste surface until discharge to the underlying drainage layer. Their findings result in lower field capacities and breakthrough times and higher unsaturated hydraulic conductivities and leachate discharge rates than obtained from models that assume homogeneous Darcian flow. Zeiss and Uguccioni's (1995) experiments confirmed that the channeled flow through municipal solid waste is a significant flow mechanism at low loading rates (0.017 mm/hr and 0.034 mm/hr) also, as less than 45 percent (maximum) of the cross-sectional area of the solid waste column conveys flow, even at steady state.  Also, the cross-sectional area did  not become significantly larger over time indicating that Darcian flow may not be the dominant flow mechanism even at steady-state conditions. However, they also observed Darcian flow through the solid waste, by virtue of measured capillary pressure in many areas of the waste column gradually decreasing over time. This was coupled with an observed increase in storage with time. These observations further questions the predictability of the above mentioned models. Zeiss and Major (1993) analyzed seven key variables used in H E L P model and found  Chapter 2. Background and Literature Review  10  them to be considerably different from the values used. For example hydraulic conductivity was found to be 10 to 10 times more than the default values used in H E L P . 4  5  Korfiatis's (1984) model was very sensitive to the changes in physical parameters such as hydraulic conductivity. Observations by Korfiatis et al. (1984) showed that moisture content continued to increase after drainage has started indicating that secondary sorption and capillary action redistribute moisture into the waste from the primary flow channels. There was no work found on flow through a landfill from a bioreactor concept.  2.4  Landfill Gas Production and Characteristics  2.4.1  Decomposition of Refuse  Once the solid wastes are placed in landfills, aerobic biological activity immediately begins to degrade the organic waste fraction. This aerobic phase results in accelerated waste consolidation, high internal temperatures and produces large volumes of carbon dioxide gas and degraded residual organics. This aerobic phase lasts for a short period of time as an oxygen deficit builds up creating semi-anaerobic conditions; conditions in which facultative anaerobes can then begin to metabolize and grow. The dominant anaerobic phase begins shortly thereafter, with the development of an obligate anaerobic population. These anaerobic bacteria will metabolize the organic carbon to CO2 and CH4. Figure 2.2 shows the most important interactions between the relevant bacterial groups, substrates and intermediate products. The anaerobic processes involved are viewed by Christensen and Kjeldsen (1989) as consisting of three stages. During the first stage solid and dissolved organic compounds  11  Chapter 2. Background and Literature Review  Complex dissolved organic matter  Solid organic matter  Hydrolysis  Dissolved organic matter Sulphate (S04)  Sulphate reducing  Fatty acids + alcohols  1<  Hydrogen sulphide (HjS)  Carbon dioxide (CO^) 1  Acetate ' Hydrogen  x  Methanogeriic\ jgcetophilicX^  ithanogenic lydrogenophilic'  Methane  (CHS  Figure 2.2: Substrates and Major Bacterial Groups Involved in the Methane Generating Ecosystem (adapted from Christensen and Kjeldsen, 1989)  Chapter 2. Background and Literature Review  12  are hydrolyzed and fermented by fermenters to primarily volatile fatty acids, alcohols, hydrogen and carbon dioxide. Refuse degradation is an example of solid state fermentation. Therefore hydrolysis is a very important process in any landfill environment since the solid organic waste must be solubilized before microbial degradation. In the second stage, an acetogenic group of bacteria converts the products from the first stage to acetic acid, hydrogen and carbon dioxide. In the final stage, methane is produced by methanogenic bacteria. This is done either by acetophiles which convert acetic acid to methane and carbon dioxide or by hydrogenophiles which convert hydrogen and carbon dioxide to methane. The conversion of acetic acid to methane is by far the most important part of the methane-forming process (Christensen and Kjeldsen, 1989).  2.5  Factors Affecting Waste Decomposition  Methane-forming ecosystems are exposed to a variety of highly variable factors in the landfill waste. The heterogeneity of the landfilled waste can make the landfill a highly diverse, but rather inefficient ecosystem. Figure 2.3 illustrates the major abiotic factors affecting the methane formation in the landfill: oxygen, hydrogen, pH, alkalinity, sulfate, nutrients, inhibitors, temperature and moisture content (Christensen and Kjeldsen, 1989). Other factors that affect waste decomposition and hence gas and leachate characteristics are: refuse composition, emplacement and particle size, the hydrogeology of landfill area, the landfill age and the gas recovery system.  2.5.1  Oxygen  The methanogenic bacteria are the most sensitive to oxygen and require a very low redox potential. Oxygen will either diffuse from the atmosphere into the landfill waste or will be carried with the infiltrating water. However, aerobic bacteria in the top layer of the  13  Chapter 2. Background and Literature Review  Oxygen Moisture  Temperature  ;  Hydrogen  Methane generating ecosystem  pH and Alkalinity  Sulphate  Inhibitors Nutrients  Figure 2.3: Major Abiotic Factors Affecting the Methane-generating Ecosystem (adapted from Christensen and Kjeldsen) landfill waste will readily consume the oxygen and limit the aerobic zone to less than 1 m of compacted waste (Christensen and Kjeldsen, 1989). Gas recovery pumping may create a vacuum in the landfill, which would force the atmospheric air into the landfill. This may extend the aerobic zone in the waste and if gas recovery pumping is over done, formation of methane in these layers would be stalled. Zehnder (1978) reported that there were no spore-forming methanogenic bacteria. But methanogenic organisms are apparently resistant to the introduction of oxygen. Anaerobic incubation of aerobic sewage and aerobic soil fairly rapidly results in methane production (Zehnder, 1978). The existence of anaerobic microenvironments in the overall aerobic environment may be one explanation for the survival of the methanogenic bacteria in aerobic environments (Christensen and Kjeldsen, 1989).  Chapter 2. Background and Literature Review  2.5.2  14  Hydrogen  According to Mclnerney and Bryant (1983), the fermentative bacteria generate hydrogen, carbon dioxide and acetic acid at low hydrogen partial pressures, while hydrogen, carbon dioxide, ethanol, butyric acid and propionic acid are generated at higher hydrogen partial pressures. Ethanol, butyric acid and propionic acid may be further utilized by acetogenic bacteria, if the hydrogen partial pressure is not too high. The conversion of propionic acid requires hydrogen pressures below 9xl0~ atmospheres (Christensen and Kjeldesen, 5  1989). Therefore if the hydrogen partial pressure is high, propionic and butyric acids will be generated but will not be further converted. Hydrogen can be consumed by methanogenic and sulfate-reducing bacteria. Hydrogen partial pressures of below 1CT atmospheres favor the formation of methane from 5  hydrogen and carbon dioxide. If the hydrogen-consuming bacteria decrease their activities, hydrogen partial pressures will be increased. This would result in the accumulation of volatile fatty acids.  2.5.3  p H and Alkalinity  Optimal pH values found in anaerobic digestion range from 6.4 to 7.4 with digestor performance collapsing at a pH of below 6.0 (Kotze et al., 1969). However, because of microenvironments and bacterial adaptability, methane production can occur at a pH less than 6.0. After refuse emplacement, there is generally, a gradual increase in pH to an optimal value.  15  Chapter 2. Background and Literature Review  2.5.4  Sulfate  According to Christensen and Kjeldsen (1989) sulfate reducing bacteria can interfere with methanogenic activity in landfills.  This group of bacteria in many ways resem-  bles the methanogenic group. They are obligate anaerobes and can utilize hydrogen, acetic acid and higher volatile fatty acids during sulfate reduction. Several laboratory experiments done by Oremland and Polcin (1982) showed retardation of methanogenesis for the substrates hydrogen and acetic acid, when sulfate ion is present.  Addition  of other substrates (e.g. trimethylamine, methanol, or methionine) caused extensive enhancement of methanogenesis, regardless of the addition of sulfate. These results showed that suppression of methane formation by sulfate is not related to any toxic effects of sulfate on methanogenic bacteria but due to simple substrate competition.  For pure  cultures of methanogenic bacteria, sulfate does not suppress methane formation. If a sulfate-reducing strain is present, in mixed cultures (e.g. Desulfovibrio), suppression is substantial due to the higher energy yielded by sulfate reduction (Zehnder et al., 1978). Sulfate is a major compound in many waste types (e.g. demolition waste, incinerator slag, fly ashes) that are disposed of in landfills. Therefore, highly active sulfate reducers may decrease the amount of organics available for methane production.  2.5.5  Nutrients  The anaerobic ecosystem must have access to all required nutrients, in particular nitrogen and phosphorus.  All the necessary micronutrients, (e.g.  sulfur, calcium, magnesium,  potassium, iron, zinc, copper, cobalt, molybdanate and selenium) are considered to be present in most landfills (Christensen and Kjeldsen, 1989). The anaerobic ecosystem assimilates only a very small part of the substrate into new cells and therefore requires much less nitrogen and phosphorus than aerobic systems. In general, the mixed waste  Chapter 2. Background and Literature Review  16  landfill will not be nitrogen or phosphorus limited but insufficient homogenization of the waste may result in nutrient-limited environments.  2.5.6  Inhibitors  The methane-forming ecosystem is sensitive to inhibitors. The inhibitory effects of oxygen, hydrogen and sulfate have already been discussed. The inhibitory effects of volatile fatty acids have been investigated and results presented in several references (McCarty and McKinney, 1961a; Kugelman and Chin, 1971). Inhibitory effects were not observed by Kugelman and Chin (1971) at a total concentration of acetic, propionic and butyric acids of up to 6000 mg/L. Carbon dioxide is produced in many of the degradation processes and its potential inhibitory effects have been investigated in sludge-fed batch reactors by Hansson and Molin (Hansson, 1979; Hansson, 1982; Hansson and Molin, 1981a,b). The removal rate of acetic acid was significantly affected by the increase of carbon dioxide partial pressure, while butyric acid removal, which does not produce carbon dioxide, was not affected. The partial pressure of carbon dioxide in a landfill may in the initial phases increase up to 0.9 atmospheres and will decrease to about 0.5 atmospheres. The mechanisms by which carbon dioxide inhibits methanogenesis are not yet known, although it has been speculated (Hansson, 1982) that the inhibition may be due to the raising of the redox potential. A second possibility is that carbon dioxide dissolves in the cell membranes of methanogens and impairs membrane function by increasing its fluidity (Senior and Kasali, 1990). MaCarty and McKinney (1961b) cited inhibition levels and stimulating levels of sodium, potassium, calcium, magnesium and ammonium (total). The inhibitory effects of ammonium are caused by free ammonia and hence are increasing with increasing pH. In landfill environments, the concentrations of the five cations are usually below the  17  Chapter 2. Background and Literature Review  Compound Copper  Toxic Concentration, mg/L 150-250 500 1000  Reference Rudgel, 1941 Rudgel, 1946 Barnes and Braidech, 1942  Nickel  200 1000  Barnes and Braidech, 1942 Wischmeyer and Chapman, 1947  Zinc  1000 350  Rudolphs and Zeller, 1932 McDermott and Barth, 1963  Nickel  2000 200  Barnes and Braidech, 1942 Pagano et al., 1950  Table 2.2: Reported Values of Toxic Concentrations of Heavy Metals in Anaerobic Waste Treatment (adapted from Kugelman and Chin, 1971)  inhibitory levels. Heavy metals concentrations at which toxicity occurs in anaerobic waste treatment systems are given in Table 2.2 (Kugelman and Chin, 1971). These are much higher than the concentrations reported for aerobic treatments. According to Kugelman and Chin, (1971) these higher tolerance levels and variability are probably due to the fact that the heavy metals take part in complex-type reactions with the normal constituents of an anaerobic waste treatment unit.  2.5.7  Temperature  The anaerobic waste degradation rate is highly affected by temperature. In laboratory simulations of landfill processes, the methane production rate has been proven to increase significantly (up to 100 times), when the temperature is raised from 20 to 30 and 40 °C (Buivid, 1980; Ehrig, 1984). In a deep landfill the flux of heat from the landfill to the surroundings is small due  18  Chapter 2. Background and Literature Review  to the insulating capacities of the waste, and the heat generated by the anaerobic decomposition process may cause a temperature rise in the landfill (Rees, 1980b). Landfill temperatures of 30 - 45 °C should be possible even in temperate climates.  2.5.8  Moisture/Water Content  Studies done on the effect of moisture content show increased methane production with increasing moisture content indicating increased stabilization of refuse. Despite the number of studies made, the question of the percentage moisture content required to facilitate increased stabilization is still a subject for debate. For example, de Walle et al. (1978) determined in laboratory studies that water saturated refuse (99%, as dry weight) resulted in maximum rates as did Klink and Ham (1982). Similarly, Rees (1981) incubated refuse core samples under anoxic conditions at in situ temperature and showed that the highest rate (300 ml/kg dry weight per day) was apparent in material sampled from below the site water table. Farquhar and Rovers (1973) demonstrated maximum gas production at moisture contents between 60 and 80% wet weight. Similarly, de Walle et al. (1978) recorded maximum methane concentrations in the presence of a refuse moisture content of 78% and recommended that landfills which were to be used for gas production should be maintained at a moisture content in excess of 75% but below 100%.  Leckie et al.  (1979) studied whether the stabilization of refuse in a sanitary landfill can be accelerated by the controlled application of moisture with a resulting reduction in the time during which the landfill presents a potential source of pollution. This study showed the test cells with initial moisture content at field capacity showed higher stabilization (higher methane concentration and low organics in leachate) than the control which did not get additional moisture after placement. Cells with recirculation 1000 gal/day (3.8 m /day, 3  17 mm/day) and continuous water addition 700 gal/day (2.7 m /day, 12 mm/day) showed 3  higher stabilization than others indicating higher methanogenic activity (high C i 7 %). 4  Chapter 2. Background and Literature Review  19  From Kasali's (1986) results it was apparent that when the moisture content was raised above 60%, gas production started to decline, thus suggesting that this discrete moisture regime satisfied the physiological requirements of the methanogenic organisms. Since, moisture promotes the mass transfer or the distribution of other methanogenic enhancement precursors (Buivid et al., 1981), it may be speculated that once such distributions were optimized, then elevated moisture contents, approaching field capacity, would be of little value since both gas and methane evolution rates would be independent of the moisture regime (Senior and Kassali, 1990). In addition, it is possible that large water additions may also introduce oxygen, thus delaying initiation of methanogenesis, and may also stimulate acidogenesis to the detriment of the initially low and slow-growing methanogenic population (Rees, 1980a). These two possibilities offer a partial explanation for the lower volume of methane generated at a moisture content of 80% versus 60%. Similar results were reported by Buivid et al. (1981). They also found a substantial decrease in methane production when the moisture content of the municipal solid waste was increased above 80%. Senior and Kasali (1990) speculated that total waterlogging, particularly during the initial stages of refuse emplacement, could be inhibitory, such that flooded sites or fills extending below the water table may not provide the optimum conditions for methane generation. Moisture flow through solid wastes is discussed in Section 2.3.3. Moisture in the refuse could be distributed unevenly due to channeling observed by Zeiss and Major (1993) and Zeiss and Uguccioni (1995). Therefore biodegradation rates could be different from place to place depending on the availability and movement of moisture. Zeiss and Uguccioni (1995) indicate that zones of intense nutrient transport and waste removal may occur around channels resulting in higher biodegradation rates in these areas. Biodegradation in other areas will still occur at a slower rate, as nutrients and wastes are transported and removed by uniform moisture fronts flowing through the solid waste matrix.  Chapter 2. Background and Literature Review  2.6  20  Landfill Leachate Characteristics  Landfill leachate strength varies considerably from landfill to landfill because of the wide range of site specific conditions; e.g., moisture content of the refuse, seasonal variations in infiltration through the refuse, composition of wastes, landfill microbiology, depth of the landfill, compacted density, use and composition of cover etc.. Table 2.3 obtained from the published literature shows typical leachate constituent concentrations for landfills. In this table Robinson et al. (1982) data were taken from analysis of 23 samples of leachate from 15 sites in the U K . Their observations showed that leachates from recently emplaced refuse contained high concentrations of dissolved organic substances, a large portion of which were short chain fatty acids. In sites where refuse has been emplaced for longer periods, the BOD, C O D and T O C in the leachate were lower. Also the ratios B O D / C O D and B O D / T O C were lower indicating the smaller proportions of biodegradable compounds from aged wastes. Characteristics of leachate reported (Jones et a l , 1985) from municipal solid waste lysimeters are presented in Table 2.3. These ranges of concentrations were extracted from the tables of the document (Jones et al., 1985) for the columns containing municipal solid wastes only. In their study, leachate was characterized over a period of 4 years for three lysimeters receiving a precipitation of 12.7 mm/week. Higher concentrations represent the initial leachate for all parameters except for pH.  2.7  Change in Landfill Gas and Leachate Characteristics with Time  Christensen and Kjeldsen, (1989) speculate on a theoretical or idealized sequence of the involved degradation processes and their consequences as to gas and leachate composition involving five distinct decomposition stages (Decomposition stages I-V) (Figure 2.4). This is based on Farquhar and Rovers (1973) and Ehrig (1984). Barlaz et al. (1989) updated  21  Chapter 2. Background and Literature Review  Compound pH* COD BOD TOC Ammonia-N Chloride Na Fe Zn TKN Alkalinity VFA Conductance +  Concentrations for landfills Robinson et al. (1982) Jasper et al. (1987) 6.26 - 7.37 6.2 - 7.4 232 - 2240 66 - 11600 10.7 - 1230 <2 - 8000 60 - 565 21 - 4400 51.9 - 236 5 - 730 93.9 - 498 70 - 2777 94.7 - 463 43 - 2500 24.5 - 127 0.09 - 380 <0.05-0.95 0.113 - 2.91 64 - 277 — 19.9 - 46.0** — <25 - 1028 — 2238 - 5751 —  Concentrations for lysimeter studies Jones et al., (1985) 4.35-6.2 5890-44800 1020-33000 1900-24500  —  70-1442 12-1225 229-1110 0.14-32.5 78-1380 184-8000 2200-11000  Table 2.3: Typical Leachate Constituent Concentrations for Landfills (all Concentrations in mg/L except *-pH units, **-meq and + -/imhos/cm)  the characterization of refuse decomposition including data on microbial population development and chemical constituents during decomposition. Their characterization study consisted of leachate recycle with neutralization in laboratory scale landfills. Summary of their characterization is given in Figure 2.5.  Characteristics of the Decomposition  stages I and II in Figure 2.4 and aerobic and anaerobic acid in Figure 2.5 are similar. Decomposition stages III, IV and V in Figure 2.4 were characterized in Barlaz et al. (1989) (Figure 2.5) in two stages; accelerated methane and decelerated methane phases. Christensen and Kjeldsen (1989) described the decomposition stages as follows; Decomposition stage I: A short aerobic stage immediately after landfilling the waste, where easily degradable organic matter (soluble sugars) is aerobically decomposed and carbon dioxide is generated. During this period, depletion of OQ, and increasing CO2 concentration will occur in the landfill environment. In Barlaz et al. (1989) study only  Chapter 2. Background and Literature Review  22  2% of the soluble sugars were oxidized during this period. Decomposition stage II: Immediately after the aerobic decomposition stage the first intermediate anaerobic stage develops.  The activity of the fermentative and the  acidogenic bacteria results in a rapid generation of volatile fatty acids, carbon dioxide and hydrogen. The acidic leachate may contain high concentrations of fatty acids, calcium, iron, heavy metal and ammonia. The latter due to hydrolysis and fermentation of proteineous compounds in particular. The concentration of nitrogen in the gas is reduced due to the generation of carbon dioxide and hydrogen. The initial high concentration of sulfate may slowly be reduced as the redox potential drops. The generated sulfide may precipitate iron, manganese and heavy metals that were dissolved in the initial part of this stage. According to Barlaz et al. (1989), pH decrease and accumulation of VFAs are due to insufficient levels of oxygen and nitrate in fresh refuse for the complete oxidation of sugars, COi  dissolution and low acid-consuming activities of the acetogenic and methanogenic  bacteria. Their data showed that cellulose and hemicellulose hydrolysis was not consistent during this phase. They suggested that the feedback inhibition of polymer hydrolysis by the accumulated carboxylic acid and any cellulose and hemicellulose hydrolysis which occurred must have aggravated the acid accumulation. Decomposition stage III: A second intermediate anaerobic stage will start with slow growth of methanogenic bacteria. The methane concentration in the gas increases, while hydrogen, carbon dioxide and volatile fatty acid concentrations decrease. Also the sulfate concentration decreases due to continued sulfate reduction. The conversion of fatty acids results in a p H and alkalinity increase which results in a decreasing solubility of calcium, iron and manganese and heavy metals. The latter are supposedly precipitated as sulfides. Ammonia is still being released and is not converted in the anaerobic environment.  Chapter 2. Background and Literature Review  23  Decomposition stage I V : The methane stage is characterized by a fairly stable methane production rate resulting in a methane concentration in the gas of 50% - 65% by volume. The high rate of methane formation maintains the low concentrations of volatile fatty acids and hydrogen. Decomposition stage V : Where only the more refractory organic carbon remains in the landfilled waste, the methane production rate will be so low that nitrogen will start appearing in the landfill gas again due to diffusion from the atmosphere. Aerobic zones and zones with redox potentials too high for methane formation will appear in the upper layers of the landfill. During accelerated methane phase Barlaz et al. (1989) measured an increase in methanogenic (cellulolytic and acetogen) populations. There was little solids hydrolysis and suggested feedback inhibition due to the acid accumulation. This phase showed the maximum methane production. During decelerated methane phase (Barlaz et al., 1989) maximum rate of solids decomposition was observed. At the end of this phase only 28% of cellulose plus hemicellulose present in fresh refuse were remaining as opposed to 63% at the end of accelerated methane phase. Continuous decrease in methane production was observed and suggested that there was a decrease in polymer hydrolysis. The above mentioned behavior of landfill gas and leachate could be seen in landfill simulators if their volume of waste is homogeneous. In real landfills the conditions are far from these. In landfills with or without cells, there is a highly varying composition and age of refuse. This could produce a completely different landfill and leachate behavior than the above presented. This can be seen from the extent of variation and ranges of the constituents presented in Table 2.3.  Chapter 2. Background and Literature Review  24  Gas composition, vol % 100 1  ,  i  Leachate  Leachate  Figure 2.4: Illustration of Developments in Gas and Leachate Composition in a Landfill Cell (adapted from Christensen and Kjeldsen, 1989)  Chapter 2. Background and Literature Review  25  Figure 2.5: Summary of Observed Trends i n Refuse Decomposition with Leachate Recycle (adapted from Barlaz et a l , 1989)  26  Chapter 2. Background and Literature Review  2.8  Effects of Infiltration of Water through Refuse  Rovers and Farquhar (1973) concluded in their work that rapid infiltration impedes methane production. The distinction between moisture volume and infiltration rate was subsequently endorsed by Klink and Ham (1982) who demonstrated methanogenic rate increases between 25% and 50% in the presence of moisture movement and found that the relationship held even when the total moisture content was constant. From their studies it was concluded that moisture content and moisture movement are separate variables affecting landfill methanogenesis.  A study by Leckie et al. (1979) described in Sec-  tion 2.5.8 showed recirculation and continuous water addition increases methanogenesis. Both these increased the infiltration. Recirculation provided higher infiltration rate (3.8 m /day, 17 mm/day) than the continuous water addition (2.7 m /day, 12 mm/day). The 3  3  cell with leachate recycle showed higher stabilization. It may be speculated that higher infiltration had an additional effect to mixing of methane precursors. From studies by Leckie et al. (1979) and Rovers and Farquhar (1973) it can be seen that up to a certain level increasing infiltration increases methanogenesis but there exists a break point infiltration rate after which methanogenesis fails. Field studies done by Wreford (1995) at Vancouver Landfill site at Burns Bog, located in Delta, British Columbia, indicated that the most significant factor affecting CR\  production was the cumulative precipitation  14 days prior to sampling. In all the cases observed by this study the periods of high moisture input coincided with peak CH production. 4  2.9  Effects of Rainfall Pattern on Landfill Leachate and Gas Characteristics  Field studies done on leachate gas characterization show a relationship of water input patterns and hydraulics of the landfill site to leachate strength and mass loading with respect to organic compounds. In Port Mann landfill, Surrey, B.C. and Premier landfill,  Chapter 2. Background and Literature Review  27  North Vancouver, B.C. peak organic concentrations coincided with the end of the peak rainfall period and the peak in the calculated leachate discharge flow rate (Jasper et al., 1987).  Similarly, at the Richmond landfill, Soper and McAlpine (1977) reported  peak concentrations occurring with high water inputs. The same trend of peak organic concentrations during high leachate flows is reported by Bull et al. (1983).  Similar  observations are reported by Rovers and Farquhar (1973) in their study of refuse placed in a 11.3 m  3  (400 cubic feet) cylindrical cell. After 115 days CH4 concentrations of 19%  (by volume) were established in their refuse columns. At that point, large amounts of water generated from melting snow and ice infiltrated the refuse causing a large increase in leachate production. The infiltration coincided with a reduction in CH4 gas concentration to 4 % (by volume) with an increase in C O D , B O D and volatile dissolved solids and a decrease in alkalinity and pH in the resulting leachate. Characteristics of these landfills and lysimeters are given in Table 2.4. Port Mann landfill leachate is characterized by low concentration of B O D and C O D , neutral pH, low level of metals, high NHz — N and moderate total salt concentrations, with little day-to-day variations and large overall trends for organic constituents (Jasper et a l , 1987). If this leachate pattern observed (mentioned earlier) is due to either or all of (1) as more water flows into, more refuse is brought up to field capacity, therefore contributing more of each constituent to the leachate, (2) due to the effect of water input on the pathways of water, and (3) due to high infiltration, additional pathways developed, it should be the trend for all the constituents. Instead, some constituents decrease, some stay constant, others increase with increasing water input. Landfills with long retention time have low organic carbon levels in leachate due to long enough retention time for methanogenesis and ones with short retention time have high organic carbon levels. When the conditions exists such that retention time shifts from long to short, then high organic carbon levels will appear in leachate, due to loss of methanogenesis.  This hypothesis  28  Chapter 2. Background and Literature Review  Landfill  Location  Average annual rainfall (mm)  Average depth during the study (m)  Type of waste disposited MSW and commercial  Age of the waste  Estimated HRT (day)  8 yrs  6 - 600  Port Mann  Surrey, British Columbia, Canada  2075  10  Premier  North Vancouver, British Columbia, Canada  2500  20 - 30  MSW and commercial  2 -3 yrs  storm response about 7 days  Richmond  Richmond, British Columbia, Canada  1000  6  MSW, commercial and industrial  5 yrs  4 - 1000  Table 2.4: Characteristics of Landfills with High Organic Carbon during High Water Input  explains the trends in Port Mann landfill as the shortest retention time corresponds to the peak concentration in organic carbon in leachate (Jasper et al., 1987). Rovers and Farquhar (1973) concluded in their work that rapid infiltration impedes methane production. Rapid infiltration decreases retention time. Recirculation of leachate in landfills improves the stabilization process. According to Pohland et al. (1980) this increased methane formation compared to a normal landfill (without recirculation) is due to the benefits of distributing methane formers and nutrients throughout the landfill mass. Recirculation of leachate increases retention time of water in the landfill. It is suggested that there is an effect from increased retention time, in addition to the benefits  Chapter 2. Background and Literature Review  29  discussed by Pohland et al. (1980). These results show that there exists an interrelated effect of hydraulic retention time, rate of infiltration and moisture content on leachate and gas characteristics. To reduce the environmental impact from landfills and to satisfy the legislation requirements concerning aqueous discharges into surface waters, treatment of leachate has become necessary. Coincidence of peak flow rates with peak concentrations, greatly increase the mass loadings of pollutants to the treatment plants which will interfere with the treatment performances. Therefore the problem of increasing organic concentrations with increased flow should be investigated and addressed before designing landfills and/or treatment plants. If the landfill hydraulic regime determines the decomposition stage of the landfill as explained earlier, it should be possible to adjust organic carbon levels in leachate by manipulating landfill hydraulics. Retention time can be changed by controlling the leachate removal or recirculation of the leachate to the top of the landfill. This is useful for existing landfills that have high seasonal organic carbon peaks of short duration. In designing new landfills, flexibility to change hydraulics can be incorporated, so that peaks can be damped out by manipulating landfill hydraulics. Therefore work should be done to understand the behavior of landfills under different retention times and varying retention times.  Trends observed in other constituents also should be explained to confirm the  above mentioned hypothesis. Also improved knowledge of the characteristics of the leachate and gas with respect to the parameters; hydraulic retention time, infiltration rate and moisture content will help the designers of landfills and leachate treatment plants. Landfill management can be effectively done if the control parameters can be manipulated to achieve the objectives such as maximizing gas production, maximizing landfill stabilization, minimizing landfill life etc..  Chapter 2. Background and Literature Review  2.10  30  Landfill Stabilization  A landfill is considered stabilized when the maximum settlement has occurred, negligible gas production is occurring and leachate does not constitute a pollution hazard. When refuse is placed in landfills, stabilization will take place as a result of physical, chemical and biological processes. In most landfills biological processes will dominate the stabilization of the waste. Microbial processes in the landfills and the factors affecting them are discussed in Sections 2.4 to 2.9. Stabilization of refuse can be accelerated by enhancing the microbial processes.  Barlaz and Ham (1990) reviewed the effects of enhancement  variables; moisture content, leachate recycle and moisture flow, particle size, innoculum addition, pH, nutrient addition and temperature addition. Stegman and Spendlin (1989) reported placing a thin layer of uncompacted, composted refuse improved methanogenesis by decreasing souring. Once the refuse is deposited in landfills, the degradable portion will be eventually degraded. The time taken to degrade the refuse will depend on the availability of factors that affect the degradation processes.  Enhancing biodegradtion processes will shorten  the time to stabilize the landfill while releasing gas and leachate during gas and leachate collection facilities are in good condition. Present landfill cover and liner requirements do not recognize this as it reduces the input of moisture, an important parameter for degradation.  2.11  Hydraulic Retention Time of Landfills  Moisture flow through the refuse was discussed in the Section 2.3.3. Also the models developed to analyze the flow through refuse were briefly discussed. There was no work done on flow characteristics of landfills considering it as a bioreactor. Flow characteristics of other bioreactors such as anaerobic digestors, anaerobic filters have been analyzed and  Chapter 2. Background and Literature Review  31  established. For an ideal plug flow reactor HRT is defined as;  HRT = ^  (2.1)  Where; V = Volume of the reactor (L ) 3  Q= Flow rate through the reactor ( L T ) 3  _ 1  Flow through a plug flow reactor does not follow this idealized flow pattern even in chemical reactors.  But according to Levenspiel (1972) a large number of designs  approximate the ideal plug flow with negligible error. In other cases deviation from the ideal can be considerable.  These deviations can be caused by channeling of fluid, by  recycling of fluid, or by creation of stagnant regions in the reactor. When it comes to the estimation of H R T for wastewater reactors assuming plug flow conditions, deviations from the ideal can be significant. Though H R T calculated assuming a plug flow is used as a control parameter in wastewater treatment plants. When it comes to landfill reactors, the contents and the volume of the reactor both are very difficult to estimate. Therefore the flow patterns could be far from plug flow. This could be the reason for the efforts by different researchers to estimate the time taken to travel (residence time) through the landfill by other means (discussed in Section 2.3.3). For nonideal flow Levenspiel (1972) defined the term mean residence time (holding time, space time) for the H R T calculated from the Equation 2.1. Residence time of water in landfills is very difficult to predict. It is dependent on many factors such as leachate collection system (whether it provides free drainage or not), depth of landfill and again on saturated and unsaturated depths, compaction of  32  Chapter 2. Background and Literature Review  Tracer input signal (stimulus)  Tracer P  N . -*" 0 Ves  ^ S c^/r  0 U t  s  u t  '8  nal  (response)  Time  T i m e  Figure 2.6: Stimulus-Response Techniques Commonly used to Study Flow in Reactors (adapted from Levenspiel, 1972 ) refuse etc.. Residence time in landfills can be changed due to many causes. Change in depth of refuse and rate of infiltration changes retention time. With increasing rainfall if the depth of saturated layer increases, retention time is increased. There is a need to investigate the term H R T as applicable to landfills. Experimental methods are used to characterize the extent of nonideal flow by means of exit age distribution function (Levenspiel, 1972).  To accomplish this, the system  is disturbed and then its response to this disturbance is measured. A n analysis of the response gives the desired information about the system. In most of the cases the stimulus is a tracer input into the reactor, whereas the response is a time record of the tracer leaving the reactor. Any material that can be detected and which does not disturb the flow pattern in the reactor can be used as tracer, and any type of input signal may be used; a random signal, a periodic signal, a step signal, or a pulse signal. These signals and their typical responses are shown in Figure 2.6. There are a variety of tracer inputs used in experiments; Fluorescin, NaCI, L i C l and  Chapter 2. Background and Literature Review  33  Rhodamine B are some of them. Among all the tracers that are used L i C l is recommended when sorption of the tracer onto the reactor contents is a concern (Branion, 1992). For a pulse input the normalized tracer response curve is called the C curve. This C curve directly gives the exit age distribution. The mean of the exit age distribution curve gives the mean residence time. This gives a good estimation of the mean flow rate through the reactor. It is not practicable to use this technique in real landfills. But it can be used in pilot scale and lab scale landfill simulators which are used to develop models. It can then be extended to the real landfill to make predictions.  2.12  Present Trends in Landfill Management and Timing of the Research  As a response to the past ground water problems and to new regulations, new landfills are Hesigned to minimize the environmental impacts. Leachate production is minimized by controlling the water inflow into the landfill using top and bottom liners. Leachate produced is collected using a drainage system and treated in in situ treatment plants before discharge into the natural water sources or discharged into sewers for treatment with domestic sewage. Gas produced is collected and used or flared reducing the impact from the landfill. This type of landfill design will keep the landfill under very low moisture conditions.  Since the moisture is a principal factor for biodegradation, the dry vault  design will extend the stabilization period of the landfill beyond that of a conventional landfill. Therefore landfills (liner systems, cover, gas and leachate collection systems etc.) should be designed for a longer life span. Otherwise the landfill will still be a threat to the environment discharging strong leachate and gas if the liner systems fail. An alternate approach was discussed by Wall and Zeiss (1995), to design and operate the landfill as an anaerobic digestor. This design consists of the bottom- and top-liner  Chapter 2. Background and Literature Review  34  systems, but may include inputs of moisture. Therefore it is important to investigate the related topics such as moisture, infiltration and seasonal variations in rainfall to explore the opportunities to incorporate moisture from these methods. The importance of moisture in the landfill stabilization is well documented as discussed in Section 2.5.8. Effects of moisture movement and infiltration are discussed in Section 2.8. The effects of infiltration have not being explored enough to use infiltration as a means of introducing moisture into the landfills or as a means of increasing stabilization of landfills. Hydraulic retention time is a function of infiltration. Improved knowledge of effects of H R T and infiltration will be beneficial in landfill planning, designing and operations.  2.13  Summary  Observations of past researchers (Soper and McAlpine, 1977; Jasper et al., 1987; Bull et al., 1983; Rovers and Farquhar, 1973) show that there exists an interrelated effect of hydraulic retention time, rate of infiltration and moisture content on leachate and gas characteristics.  To reduce the environmental impact from landfills and to satisfy the  legislation requirements concerning aqueous discharges into surface waters, treatment of leachate has become necessary. Coincidence of peak flow rates with peak concentrations, greatly increase the mass loadings of pollutants to the treatment plants which will interfere with the treatment performances. Therefore the problem of increasing organic concentrations with increased flow should be investigated and addressed before designing landfills and/or treatment plants. If the landfill hydraulic regime determines the decomposition stage of the landfill as explained earlier, it should be possible to adjust organic carbon levels in leachate by manipulating landfill hydraulics. Retention time can be changed by controlling the leachate removal or recirculation of the leachate to the top of the landfill. This is useful  Chapter 2. Background and Literature Review  35  for existing landfills that have high seasonal organic carbon peaks of short duration. In designing new landfills, flexibility to change hydraulics can be incorporated, so that peaks can be damped out by manipulating landfill hydraulics. Therefore, work should be done to understand the behavior of landfills under different retention times and varying retention times. Also, improved knowledge of the characteristics of the leachate and gas with respect to the parameters; hydraulic retention time, infiltration rate and moisture content will help the designers of landfills and leachate treatment plants. Landfill management can be effectively done if the control parameters can be manipulated to achieve the objectives such as maximizing gas production, maximizing landfill stabilization and minimizing landfill life.  Chapter 3  Objectives  Observations of landfill leachate characteristics have shown a trend of increasing organic carbon with increasing rainfall or water input (Soper and McAlpine, 1977; Jasper et al., 1987; Bull et al., 1983; Rovers and Farquhar, 1973). The proposed hypothesis was that methanogenesis failure was due to the reduction in Hydraulic Retention Time (HRT) with increasing infiltration. Rovers and Farquhar (1973) concluded in their work that rapid infiltration impedes methanogenesis.  In the study by Jasper et al., (1987), char-  acterization of gas was not done. Alternatively Leckie et al. (1979) observed increasing methanogenesis with increasing infiltration through the refuse although his infiltration rates were relatively low.  Studies by Rovers and Farquhar (1973) and Leckie et al.  (1979) showed that there exists a breakthrough infiltration after which methanogenesis fails. Coincidence of peak infiltration rates with increased organic carbon concentrations would greatly increase the pollutant loadings to the treatment plants which will interfere with the treatment plant performances.  Therefore, it is necessary to understand this  relationship to facilitate the design of landfills and treatment facilities for leachate. The objectives of this research were; 1. To study the effects of Hydraulic Retention Time (HRT) on landfill leachate and gas characteristics. 2. To explore the breakthrough infiltration rate for methanogenesis. 3. To propose possible explanations for the increasing organic loadings in landfill leachates. 36  37  Chapter 3. Objectives  To achieve these objectives, eighteen landfill simulators were constructed. To compare the effects due to different HRTs, other factors that affect leachate and gas characteristics were kept to a minimum. Since the refuse filled was fresh from houses there was concern regarding the time to establish methanogenesis. Therefore anaerobic digestor sludge was added as a seed to initiate methanogenesis. The experiments were conducted in four phases.  The purpose of phase I was to  investigate the reproducibility of all columns under identical independent variables. This phase lasted for 163 days. Phases II and III were done to demonstrate the effects of H R T on landfill leachate and gas characteristics. Leachate characterization studies discussed in Section 2.9 showed higher concentrations of organics coincide with high water inputs. The H R T was changed by changing infiltration rate. Different HRTs were established in each column and confirmed using tracer study. To study the variation of H R T with time (decomposition of refuse) a second tracer study was done for columns 7 and 10. There was no indication of failure of methanogenesis under the range of HRTs assigned during phase II. As the objective of exploring the breakthrough H R T (infiltration rate) for methanogenesis was not accomplished during phase II, the H R T was further lowered by increasing the infiltration rate (phase III). Columns 16 and 18 were assigned the HRTs of 6 and 3 days as a preliminary study to phase III. There was no indication of failure of methanogenesis but an enhancement was observed. Phase II and III lasted for 300 days and 60 days, respectively. HRTs of the remaining columns (except 7, 10, and 15) were reduced to 13 days to see whether there is an effect from the original H R T on the characteristics of leachate and gas when H R T is lowered. During phase IV gas was characterized for a further 90 days to see the effects of succession of infiltration through the columns.  Chapter 4  Experimental Methods and Analytical Procedures  Characteristics of gas and leachate are affected by many environmental parameters. This research was aimed at finding the effects of H R T on landfill leachate and gas characteristics.  Therefore, experiments were designed in a way to minimize effects from other  parameters. The experiments were located in the laboratory to minimize temperature fluctuations throughout the research.  Composition of the refuse filled was the same.  Mixing and filling the refuse according to the composition was done in small batches to achieve a uniform composition in the columns. Eight batches were needed to fill one column.  4.1  Experimental Set-up  4.1.1  Construction of Lysimeters  Eighteen lysimeters were constructed using 30 cm diameter by 180 cm high P V C pipes as shown in Figure 4.1. The flanges at the top and the cones at the bottom were fabricated using fiber glass. Flexible tubing of 12 mm diameter was fixed to the bottom. A loop in the tubing was used to prevent entry of air from the bottom. The bottom of the column (cone shaped part) was filled with 19 mm gravel with a layer of pea gravel on top. This was done to provide free drainage of leachate. A frame was constructed to position the 18 columns vertical. Columns were tested for water leaks by filling them with water. After the columns  38  39  Chapter 4. Experimental Methods and Analytical Procedures  water tank  teed Vvdter  pump  to vent 40 cm  gas sampling port  wet gas meter  29 cm diameter PVCpipe compacted refuse 140 cm  pea gravel  Figure 4.1: Schematic of the Experimental Set-up  Chapter 4. Experimental Methods and Analytical Procedures  Material Paper Plastic Organics (food, garden waste etc.) Metals Glass Total  Quantity Weight per batch (kg) 1.93 0.35 3.20 0.35 0.25 6.08  40  % 31.7 5.7 52.6 5.7 4.1 100  Table 4.1: Composition of Refuse  were prepared (Section 4.1.3) lids were placed and sealed carefully. Air tightness of the columns was very important since gas production rates were measured. Also air tight columns were necessary to measure the gas production rates since the functioning of the gas meters was dependent on it. All the gas meters showed build-up of the small pressure in the columns indicating airtight columns.  4.1.2  Filling of Refuse in the Columns  Refuse was collected separately for each category shown in Table 4.1. This is the composition of refuse typical to the Greater Vancouver Area (Waste Program Consortium, 1992) and reflects the existence of an active recycling program (paper, plastic, metal and glass) at the residential level.  Food Waste Food waste was collected from U B C family housing during April and May 1993. Residents separated their food waste from other refuse and put it into zip lock bags each day (this was done for their convenience) and stored in a garbage bag for weekly collection. After collection, the bags were emptied into big garbage bags and were stored at 4 ° C until the columns were ready to be filled. Food waste was not shredded.  Chapter 4. Experimental Methods and Analytical Procedures  41  Paper Shredded ( 2 - 4 cm) mixed paper was taken from a mobile shredding truck of Proshred Company Limited.  Plastic Plastic was taken from the Vancouver Transfer Station at Kent Avenue. These were shredded to a size of approximately 2-4 cm by the mobile shredder of Proshred Company Limited.  Metal Metals were brought from Vancouver Transfer Station at Kent Avenue and shredded to a size of 2 - 4 cm by the mobile shredder of Proshred Company Limited.  Glass Glass was collected from my home and lab and broken into pieces of size 2 - 4  cm by  tamping in a bucket.  Yard Waste Yard waste was collected from Keremeos court, U B C family housing cleanups. This waste included leaves, dirt, weeds and soil. Another portion of yard waste included cut grass and was collected from the field near B.C. Research. Moisture content of the mixed waste was measured by drying the samples at 104 ° C . This was done prior to filling the columns for a batch of garbage collected from home (same composition of materials).  Chapter 4. Experimental Methods and Analytical Procedures  42  After collecting all the refuse, the columns were filled according to the composition in Table 4.1. Weights from each category as in Table 4.1 were measured and mixed in a concrete mixer. Eight batches were needed to fill a column. The batches were compacted to 120 cm height by tamping using a wooden block fixed to a steel rod. Columns were filled one at a time. Four kilograms of additional yard waste/cut grass was added to each column and compacted to 20 cm. All the columns were compacted to a height of 140 cm to achieve a density (wet weight basis) of 570 kg/m . After measuring the moisture absorbed (discussed in Section 4.1.3) 3  10 liters of anaerobic digestor sludge from Lions gate sewage treatment plant was added as a seed. On the same day the columns were covered with plates which were fitted with plumbing for exit gas and inlet water. Drain tubes were closed to avoid loss of water. Other than the exit gas tube explained in the following paragraph all other joints were sealed to prevent air entry. Eighteen wet gas meters were placed in a platform, constructed near the columns and connected to each column. A schematic of a wet gas meter is shown in Figure 4.2. Since flexible tubing is permeable to gas, C u tubing was used for plumbing. The exit gas tubes were connected to the wet gas meters. Calibration of each gas meter was done before connecting. Columns 16, 7, 18 and 1 were the first columns to be connected. The others except 10 and 13 were connected over a period of two weeks. Columns 13 and 10, because of mechanical problems, were connected about 6 weeks after the first group. Once a gas meter is connected to a column the column becomes completely sealed against air entry. Water was pumped to the lysimeters from a 40 liter capacity overhead tank. The tank was fed using a tube connected to a tap near the columns. For the infiltration a proportioning pump (Model Pump III from Pulse Instrumentation Ltd.) that can accommodate 26 channels (tubes) was installed and plumbing was done with flexible tygon tubing. Leachate was discharged to a drain unless samples were being collected.  43  Chapter 4. Experimental Methods and Analytical Procedures  Gas exit  Magnet Gas enter Counter Sensor  Gas Collected Figure 4.2: Schematic of a Wet Gas Meter  4.1.3  Preparation of Columns for the Study  After the experimental landfill columns were set-up, and filled with refuse, they were flooded with water and let stand for 4 days so that the refuse was well wetted.  The  saturating water was then drained and measured. A water balance was done to calculate the amount of water absorbed. Moisture at placement was calculated from initial moisture content data. Characteristics of the prepared column and feed water are given in Table 4.2.  4.2  Selection of H R T s for the Study  HRTs of the landfills where leachate organic carbon increased with increasing water input are given Table 2.4. Lower HRTs correspond to rainfall events during winter. These rainfall events last for shorter periods. Depth of the laboratory scale lysimeters used is much  Chapter 4. Experimental  Methods and Analytical  44  Procedures  Condition/Characteristic Refuse weight at placement wet weight (kg) Refuse height at placement (cm) Refuse compacted density (kg/m ) Moisture content at placement (% wet weight basis) Temperature of feed water (°C) Alkalinity of feed water (mg/L as CaCOz) Hardness of feed water (mg/L as CaCOz) pH Temperature of the laboratory where the columns were kept (°C)  52.64 140 570  3  36 15 - 18.8 1.1 - 1.5 3.10 - 3.93 5.9 - 6.0 15 - 27  Table 4.2: Characteristics of the Prepared Columns and Feed Water  smaller than the real landfills. Achieving higher HRTs will need the addition of small volumes of water at spaced intervals. For lower HRTs high volumes are needed at shorter intervals. It was not practical to use different time intervals for different columns. Also it would create different unpredictable hydraulic conditions in each column. Therefore it was decided to manipulate the HRTs using continuous application of water. The main source of infiltrating water for landfills is precipitation. Precipitation on landfills varies from landfill to landfill with time.  Annual precipitation in Vancouver,  B.C. landfills are in the range of 1000 mm to 2350 mm. This is not distributed evenly throughout the year. For example Vancouver receives most of its rainfall from September to May. June, July and August are considered dry months.  Therefore 1000 mm to  2350 mm precipitation will be often distributed over nine months, instead of twelve months. Port Mann landfill, Vancouver discussed in Section 2.9 does not have any surface runoff during rainfall events. Therefore all of its 2350 mm of rain infiltrates through the refuse creating lower hydraulic retention times. Rainfall in other parts of the world with monsoon rain creates even lower HRTs. For  45  Chapter 4. Experimental Methods and Analytical Procedures  example Sri Lanka's annual rainfalls for the years 1990 and 1991 ranged from 1700 mm to 4300 mm for different regions in the country. These included daily rainfalls from trace amounts to 162 mm. Rainfall events produce much higher infiltration rates. For example; the maximum daily rainfall in Vancouver International Airport for the year 1993 was 33 mm. For Port Mann landfill it was even higher. To create the hydraulics in the refuse similar to 33 mm/day, an infiltration rate of 2300 ml/day was needed. A n infiltration rate of 2300 ml/day was chosen as the highest infiltration rate which gives an H R T of 18 days. Other HRTs higher than this were selected up to 200 days which corresponded to the lowest flow rate available in the pump. Failure of methanogenesis was expected within the wide range of HRTs used 18 - 200 days. Over the 300 day period there was no sign of failure of methanogenesis. Therefore columns 16 and 18 were given very low HRTs of 6 and 3 days (infiltration rates 5600 ml/day and 11200 ml/day respectively) in order to see a breakthrough infiltration rate. An infiltration rate of 11200 ml/day simulates the hydraulics for a daily precipitation of 170 mm. This is similar to the highest daily rainfall for Sri Lanka mentioned earlier. After 55 days of these low HRTs there was no sign of failure of methanogenesis.  Since  HRTs lower than this are not realistic it was decided that there is no breakthrough H R T beyond which methanogenesis fails. Therefore further lowering of H R T was not done. During phase III, HRTs of all the other columns were decreased to 13 days. This was done to see whether there is an effect from the original H R T (phase II HRTs) on the behavior of the columns (characteristics of leachate and gas) when the H R T is lowered.  Chapter 4. Experimental Methods and Analytical Procedures  4.3  46  Methodology-Phase I  Construction, refuse filling and preparation of the columns were done with the intention of making 18 identical columns. It was necessary to confirm this before starting the experiments to see the effects of HRT. Once the experimental set-up was completed continuous addition of water at a rate of 1150 ml/day (HRT = 35 days) was started. Sampling and analysis of gas and leachate were done every two weeks except for the third set of samples which were taken three weeks after the second sampling. Volume of gas produced was measured weekly using the wet gas meters. Gas was analyzed for CH/L,  CO2, N2 and 0 2 . Leachate was collected in sampling bottles set at the end of  the drain tubes. Leachate was analyzed for V F A , C O D , total organic carbon, inorganic carbon, volatile solids, dissolved solids, total solids, NHz — N, T K N , zinc, iron, sodium, pH, specific conductance, chlorides and alkalinity. Column 16 was chosen to do a tracer study to confirm the H R T assigned to the columns.  A slug of L i C l was added and leachate was analyzed for L i . Samples were  taken daily until the peak of the curve has passed, then every two days for about 14 days and randomly after that to complete the tracer curve. During this period only few columns established methanogenesis completely. But it was necessary to move to the next phase of the experiments as flushing of the columns was reducing measurable concentrations.  Delaying the initiation of the H R T changes  could have resulted in an inability to detect leachate changes.  4.4  Methodology-Phase II  After 163 days of preliminary runs, the new column HRTs (18, 60, 120 and 200 days) were developed in the columns by changing the flow rates from 1150 ml/day to 2300, 600, 330, and 230 ml/day respectively. HRTs were assigned in triplicates. When selecting  47  Chapter 4. Experimental Methods and Analytical Procedures  Column # 1,3,4 2,7,10,13,16,18 5,8,9 6,15,17 11,12,14  Experimental condition HRT(day) Flow rate(ml/day) 60 35 120 200 18  600 1150 330 230 2300  Table 4.3: Experimental Design for Phase II  triplicates, columns with identical gas composition and gas production pattern were taken. Six columns were left at the original H R T (35 days) as controls. Table 4.3 shows the experimental design for the Phase II. Sampling and analysis of leachate and gas were done bi-weekly (at the beginning), tri-weekly (middle of phase II) and monthly (towards the end). Gas production rates were measured by taking wet gas meter readings weekly. Analytical parameters for gas composition and leachate were same as phase I except chlorides were not measured since they decreased to the levels not detectable by the chloride ion electrode. A tracer study was carried out using LiCl as the tracer, to confirm the HRTs assigned. A slug of tracer was added to each column and leachate was analyzed for L i . Sampling frequency of leachate for the tracer was determined for each column (HRT) according to the stage of the tracer curve. For example for lower HRTs at the beginning and near the peak, sampling was done every day and then every other day. But for the tail end of the curve, samples were taken weekly and bi-weekly. Tracer curves for the columns 6, 15 and 17 were not complete enough by the end of phase II. Therefore column 15 was left out from the phase III to complete the tracer curve. Before the tracer curve was complete in column 15 the experiments were stopped due to the failure of the pump after running continuously for 600 days.  Chapter 4. Experimental Methods and Analytical Procedures  Column # 1,2,3,4,5,6,8,9,11,12,14,17 7,10 15 16 18  48  Experimental condition HRT(day) Flow rate (ml/day) 13 2800 35 1150 200 230 6 5600 3 12000  Table 4.4: Experimental Design for Phase III  4.5  Methodology-Phase III  As a trial for phase III of the experiments, columns 16 and 18 were given very low HRTs, 6 (flow rate = 5600 ml/day) and 3 (flow rate = 11200 ml/day) days respectively. After 68 days of trial experiment, all the columns except columns 7, 10, 15, 16 and 18 were given an H R T of 13 days (flow rate = 2800 ml/day). Columns 7 and 10 were left at original H R T to do another tracer study. Column 15 was left unchanged to complete its tracer curve. Leachate and gas were sampled weekly at the beginning and bi-weekly after that. Gas was analyzed for C i 7 , C0 , 4  2  N  2  and 0 . 2  Leachate was analyzed for V F A , C O D ,  total organic carbon, inorganic carbon, pH, specific conductance and alkalinity. Gas production rates were measured by taking wet gas meter readings weekly.  Table 4.4  summarizes the experimental design for the phase III. Tracer studies were done to columns 7 and 10 to see whether there was any change of H R T in these columns after 8 months, due to decomposition. A slug of tracer was added to each column and the leachate was analyzed for L i . Leachate was sampled daily until the peak of the curve had passed and randomly after that.  49  Chapter 4. Experimental Methods and Analytical Procedures  Time Frame Time Column #  Phase I 10/04/93-3/18/93 163 days Infiltration HRT Rate(ml/day)  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150 1150  (day) 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35  Phase II 3/18/94-1/13/95 300 days Infiltration HRT Rate (ml/day) (day) 600 1150 600 600 330 230 1150 330 330 1150 2300 2300 1150 2300 230 1150 230 1150  60 35 60 60 120 200 35 120 120 35 18 18 35 18 200 35 200 35  Phase III * 1/13/95-3/29/95 75 days Infiltration HRT Rate (ml/day) (day) 2800 2800 2800 2800 2800 2800 1150 2800 2800 1150 2800 2800 2800 2800 230 5600 2800 11200  13 13 13 13 13 13 35 13 13 35 13 13 13 13 200 6 13 3  Table 4.5: Summary of Experimental Conditions during the Research. *Note: Phase III for columns 16 and 18 were started on 11/16/94 as a trial for the Phase III  4.6  Methodology-Phase IV  After running the experiment at the HRTs in phase III for 75 days, the addition of water to all the columns was stopped; and the water was allowed to drain. Gas was analyzed for the following 90 days for CH±, CO2, N2 and 02- Gas production rates were measured for 112 days by taking wet gas meter readings weekly. A summary of experimental conditions for phases I, II and III of the study is given in Table 4.5.  Chapter 4. Experimental Methods and Analytical Procedures  4.7  50  Tracer Experiments  Tracer tests were conducted at different stages of the research as described in Sections 4.3 - 4.5. Mass of tracer used in each test are given in Table 4.6.  Column # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  LiCl mass used (g) Phase I Phase II Phase III 5 — — — 5 — — — 5 — 5 — — 5 — — 5 — — 5 10 5 — — — 5 — 5 10 — — 7 — — 7 — — • 5 — — — 7 — 5 — — 9.9 5 5 — — 5 — —  Table 4.6: L i C l Mass used in Tracer Studies  Chapter 4. Experimental Methods and Analytical Procedures  4.8  51  Analytical Procedures  Sampling of leachate and gas were done at time intervals as discussed in Sections 4.3, 4.4, 4.5 and 4.6. Leachate was directed to sampling bottles for a period depending on the flow rates in the columns. Sampling, handling and preservation times before analysis were kept to a minimum. Most analysis were done on the same day of sampling. The majority of the tests were conducted in accordance with Standard Methods (A.P.H.A. et al., 1992). The exception was C O D for the samples with C O D less than 100 mg/L. Samples were diluted using distilled water where necessary.  4.8.1  pH  A Beckman 44 pH meter with automatic temperature compensation was used to determine the pH of the samples. The meter was calibrated daily, prior to measurements, using two standard buffer solutions of pH 4.0 and 7.0. Detection limit = 0.01 pH units.  4.8.2  Volatile Fatty Acids (VFAs)  The volatile fatty acid determination was conducted using a Hewlett-Packard 5880A gas chromatograph, equipped with a Flame Ionization Detector (FID) using the method described in Supelco Bulletin 751. Helium was used as the carrier gas. Volatile fatty acids analyzed include; acetic, propionic, butyric, iso-butyric, valeric and 2-methylbutyric. Samples were acidified with 5% phosphoric acid to bring the pH below 3, 1 ml of the sample was dispensed to V F A vials and stored at 4 °C until analysis. Samples were kept frozen at -17 °C in sealed plastic bottles, when preserving to pH below 3 was delayed for more than 12 hrs after sampling. Detection limit = 1 mg/L for each volatile fatty acid.  Chapter 4. Experimental Methods and Analytical Procedures  4.8.3  52  Chemical Oxygen Demand (COD)  Samples were analyzed for C O D using the dichromate reflux procedure outlined in Standard Methods (A.P.H.A. et al., 1992) when the C O D is within the range 100 - 900 m g / L (detection limit = 20 mg/L). Samples were diluted depending on the expected C O D of each sample to fit to the above range. When the C O D was below 100 mg/L, the procedure was done according to the H A C H company DR/2000 spectrophotometer procedure manual. C O D dichromate reflux method for the range 0 - 150 mg/L was used (detection limit = 3 mg/L).  4.8.4  Total Organic Carbon ( T O C ) and Inorganic Carbon (IC)  T O C and IC were determined on a Shimadzu Total Organic Carbon Analyzer (Model TOC-500) using a series of low and high standards, as described in the Instruction Manual (Shimadzu Corporation, 1987). Samples were diluted using distilled water for T O C where necessary. Inorganic Carbon was analyzed on undiluted samples. T O C was calculated using the relationship T O C = T C - IC. Detection limit = 1 mg/L.  4.8.5  Alkalinity  Total alkalinity was measured by titrating the samples to an end point pH of 4.5 with sulfuric acid. Normality of sulfuric acid (between 0.2 N and 0.02 N) used was decided based on the expected alkalinity of the samples so that the titrant volume is about 20 ml. One normality was used for all the samples in one day. A sample volume of 25 ml was used. Samples were analyzed within 4 hours of collecting. Detection limit = 5 mg CaC0 /L. 3  Chapter 4. Experimental Methods and Analytical Procedures  4.8.6  53  Specific Conductance  Conductivity was measured using a BACH-SIMPSON L t d . ( T Y P E C D M 3) conductivity meter.  4.8.7  Solids  Total Solids (TS) and Volatile Solids (VS) Both T S and VS analyses were performed as outlined in Standard Methods (A.P.H.A. et al., 1992). Total solids were determined by evaporating a known volume of well-mixed sample in a Fisher Isotemp (Model 350) forced draft oven at 104 °C. To measure the volatile solid content the residue was ignited at 550 °C in a Lindberg muffle furnace (Type 51828). Detection limit = 6 mg/L.  Total Suspended Solids (TSS) Total suspended solid content of the samples was analyzed in accordance with Standard Methods (A.P.H.A. et al., 1992). A known volume of sample was vacuum filtered through pre-washed and oven-dried Whatman 934-AH glass microfibre filter and dried at 104 °C for TSS analysis. Detection limit = 3 mg/L.  4.8.8  Nitrogen  TKN Total Kjeldahl Nitrogen was measured by digesting the samples in a BD-40 Technicon Block Digester with concentrated H2SO4  and K^SO^ to liberate all organically bound  nitrogen. Analysis was performed colorimetrically following the instructions in the Lachat  54  Chapter 4. Experimental Methods and Analytical Procedures  QuickChem Automated Ion Analyzer according to QuickChem Method No. 10-107-062-E. Detection limit = 0.1 mg N / L .  A m m o n i a Nitrogen Samples were filtered (Whatman #4), preserved to pH less than 2 by addition of concentrated sulfuric acid, and refrigerated in plastic tubes at 4°C. Ammonia nitrogen was analyzed by the automated phenate method using Lachat QuickChem Automated Ion Analyzer in accordance with the Method No. 10-107-06-1-Z. Appropriate dilutions were done using distilled water where necessary. Detection limit = 0.05 mg N / L .  4.8.9  Metals  Zinc, iron and sodium were analyzed in accordance with the Standard Methods (A.P.H. A. et al., 1992). Fifty milli-liters of sample was digested with cone. HNO^  and analyzed  on an atomic adsorption/atomic emission sprectophotometer (Thermo Jarrel Ash Corporation, model No. V I D E O 22) using atomic absorption. Detection limits at the most sensitive wave lengths are 0.002 mg/L as Na, 0.01 mg/L as Zn and 0.05 mg/L as Fe for Na, Zn and Fe respectively. For the tracer study, Lithium was analyzed in accordance with the Standard Methods (A.P.H. A. et al., 1992) on undigested samples. Flame emission method was used in atomic adsorption/atomic emission sprectophotometer.  4.8.10  Chloride  Chloride was measured initially by the Mercuric Nitrate Method in accordance with the Standard Methods (A.P.H.A. et al., 1992). Due to the turbidity and color of the samples it was not possible to detect the end point accurately. Therefore a chloride ion electrode  55  Chapter 4. Experimental Methods and Analytical Procedures  w i t h p H meter M o d e l 50 from Fisher Scientific was used.  4.8.11  Gas Analysis  Gas sampling was done two days prior to leachate sampling. Sampling was done from each column through the gas sampling ports using an 1 m l H a m i l t o n syringe and rapid injection into a Fisher-Hamilton Gas Partitioner (Model 29), using helium as the carrier gas and a thermal conductivity detector. Gases were identified by comparing the peak areas w i t h known standards that were used to determine response factors.  4.9  Statistics  Standard deviations were calculated using the statistics package Systat for windows version 5. Simple linear regression analysis was done for zinc and iron concentrations w i t h p H and CH4 production rate using Microsoft E x c e l Version 5. A confidence level of 0.05 was used to perform analysis of variance ( A N O V A ) and when was rejected.  F  >  Fcrmcai  null hypothesis  Chapter 5  Results and Discussion  5.1  Introduction  A complete description of the methodology of the research is given in the Chapter 4. In this section an introduction to the contents of this chapter is presented. Also the general performance of the columns and the problems encountered during the research which will be helpful in the interpretation of data, are presented. Phase I was done to establish an understanding of the performance of all the columns and even though care was taken to produce identical refuse columns, the columns behaved differently.  This gave the opportunity to observe the effects of H R T under different  stages of the refuse decomposition and leachate characteristics. Phase I also gave the opportunity to acknowledge the differences in characteristics of the columns instead of assuming they would all behave similarly due to the efforts went into producing identical columns as one would generally expect. The columns were sealed after filling with refuse and adding anaerobic digester sludge.  Therefore, a continuous decrease of available  organics in the system occurred during the study. When the HRTs were changed at the beginning of phase II and phase III, available organics and the stage of the decomposition were likely different, even though the leachate from each of the columns was nearly identical. Due to the above mentioned differences, only the gas composition was directly compared between the columns and phases II and III (i.e., HRT). As explained in the Chapter 4, water was pumped to the columns from an overhead  56  Chapter 5. Results and Discussion  57  tank. This tank was fed from a nearby tap with a very low flow rate. Because of the very low flow rate from the water tap, accumulation of dirt in the valve stopped the flow to the tank. On three occasions during the 550 day experiment (day 120, 390 and 500), there was not enough water in the tank to pump. As a result of this, air was pumped to the columns. The N and 0 2  2  data points, shown in the gas composition, confirm this.  During the experiment, columns 7 and 10 had an H R T of 35 days (predicted) throughout the research and were considered as controls. During phase I and II columns 2, 13, 16 and 18 also had an H R T of 35 days (predicted) and are also considered as controls for those phases. These were considered as controls with respect to the changes in operational variables. As any researcher on landfills would know one cannot have/consider a landfill to be a control with respect to the characteristics of leachate being constant but might be able to have with respect to gas composition as this tends to remain constant over a longer period. Due to these, direct comparison of leachate characteristics in terms of numbers will not be done, rather trends were compared. Gas characteristics comparisons were done with respect to these columns. To observe the effects of Hydraulic Retention Time (HRT) on landfills, it was necessary to establish a relationship for H R T in landfills and means of controlling it. A model to determine H R T in landfills was developed and is discussed in Section 5.2.  Tracer  studies were done at different stages of the research to confirm the HRTs assigned in the columns and to strengthen the established relationship. Results of these are discussed in Section 5.2.1. The general characteristics of leachate and gas are discussed in Sections 5.3 and 5.5.  The effects of H R T on landfill gas and leachate are presented and discussed in  Sections 5.4 and 5.6. Pollutants released to the environment are discussed in Section 5.7. Microenvironments and carbon released to the environment are discussed in Sections 5.8 and 5.9, respectively.  Effects of H R T on landfill leachate and gas characteristics are  58  Chapter 5. Results and Discussion  reviewed as a whole in Section 5.10. Potential applications of the findings are discussed in Section 5.11. Figures in this chapter are presented at the end of respective sections or sub sections.  Predicted HRTs were used in the discussions.  Raw data for gas and leachate  characteristics are given in Appendices F and G.  5.2  Hydraulic Retention Time for Landfills  H R T in landfills is very difficult to predict. It is dependent on many factors such as, a leachate collection system (whether it provides free drainage or not), depth of landfill and again on saturated and unsaturated depths, compaction of refuse etc..  H R T in  landfills can change due to many causes. For example; change in depth of refuse or rate of infiltration changes retention time. With increasing rainfall if the depth of saturated layer increases, retention time is increased. As in plug flow reactors, H R T in landfills should be predictable if one knows the volume of water in the landfill. However, for landfills, unlike reactors, it is not directly measurable. For an ideal plug flow reactor H R T is defined as in Equation 2.1.  It is assumed  that the flow rate through refuse is plug flow. But water holding capacity of a reactor filled with refuse is much less than the actual volume of the reactor; even less, when the reactor is designed to be free draining. It is proposed by this author that the following relationship given in Equation 5.2 holds true for the H R T in the landfill.  59  Chapter 5. Results and Discussion  For unsaturated landfills; HRT  = —  (5.2)  Q  Where; S = Volumetric water holding capacity of the solid waste in the landfill X Volume of the solid waste in the landfill (L ) 3  Q = Flow rate through the landfill ( L T ) 3  _ 1  Water holding capacity of the reactor (landfill) is the total amount of water that can be sorbed by the refuse i.e., including moisture at placement in the refuse. This is often known as field capacity (Section 2.3.2). Water holding capacities of the columns were estimated before starting the experiments. Moisture content of the refuse at placement was measured to be 36 % wet weight basis (57.5 % dry weight basis). Water sorbed was measured by saturating the refuse columns for four days and then letting them drain. Addition of the amount of water sorbed and moisture at placement gives the water holding capacity. Water sorbed by each column was different, as shown in Table 5.1. When estimating the initial moisture content, samples were taken for the total refuse mass, not for each column. Therefore, 18.95 L of moisture at placement is an average value for all the columns. As such, differences in water absorbed could be due to differences in moisture at placement. Therefore when calculating HRTs, average moisture holding capacity for all the columns (i.e., 36.5 L) was taken. Field capacity (water holding capacity) of the refuse was 36.5% volume basis and 69% wet weight basis (i.e., 365 mm/m). This is comparable to the results published by Holmes, 1980 (Table 2.1) for the density of 600 kg/m , but much higher than the value, z  100 mm/m, reported by Rovers and Farquhar (1973).  60  Chapter 5. Results and Discussion  Column #  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Average SD  Volume of water absorbed  Moisture at placement  S  (L) 16.65 17.86 17.88 18.31 15.83 18.02 13.06 17.75 19.36 18.61 21.61 16.37 18.19 18.94 18.34 15.75 17.01 16.59 17.56 1.79  (L) 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95 18.95  (L) 35.6 36.81 36.83 37.26 34.78 36.97 32.01 36.70 38.31 37.56 40.56 35.32 37.14 37.89 37.29 34.70 35.96 35.54 36.5  —  —  Table 5.1: Moisture Absorbed and Field Capacities of the Columns  In this research H R T was controlled by regulating the flow rate (infiltration rate). Height of the refuse was kept the same in all the columns. The bottoms of the refuse lysimeters were filled with pea gravel to ensure free draining (i.e., no saturated depths). HRTs were calculated using the Equation 5.2. Where S = 36.5 liters and Q being the flow rate through the column. Flow rates were measured by collecting leachate at the bottom from time to time and the average was used in the calculation of the H R T predicted.  Chapter 5. Results and  61  Discussion  Example: For columns 1, 3 and 4 Average flow rate (Q)  = 600 ml/day  Water holding capacity (S) = 36.5 liters from Equation 5.2 36500 ml/(600 ml/day)  HRT  = 60.8 day  5.2.1  Tracer Experiments  To confirm the model developed and the HRTs assigned to columns a tracer study was conducted. The tracer response curves are shown in Figures 5.1 - 5.5. From the tracer curves it can be seen that there are no multiple peaks. This indicates that channeling was not present in these columns. The mean residence time (HRT) and variance of a tracer curve is calculated using Equations 5.3 and 5.4 when data is collected by instantaneous readings (Levenspiel, 1984).  j _ E £ r ( * * + i + *t)(ci+i + c*)(*i+i -  JXl(U+l  + U) (c 2  ^Zl{c  i+1  i+l  +  + Cj)(t  i+1  - tj)  Ci)(t -U) i+l  Where; t  Mean residence time (T) Variance (T ) 2  U  i  th  time the concentration of tracer measured (T)  Concentration of the tracer at ti ( M L ) - 3  u)  (5.3)  -  2  (5.4)  62  Chapter 5. Results and Discussion  From the Tracer Curve Column  #  t (day) 78 79 79 37 42 48 48 35 39 118 136 160 28 30 27  1 3 4 2 7 10 13 16 18 5 8 9 11 12 14  Table 5.2: t, a  2  a (day ) 1170 1267 1286 470 463 331 359 490 474 2622 2321 1659 298 264 321 2  2  Recovered Tracer Mass (%)  19 21 19 17 15 20 19 23 19 18 17 17 21 19 23  and Percentage of Mass of Tracer Recovered  The mean residence time and the variance for the curves (except for columns 6, 15 and 17 where tracer curves were not complete enough) were estimated and presented in the Table 5.2. Levenspeil (1984) warns of the limitation of this approach to finding the mean residence time (HRT) when the tracer disappears from its flowing phase either by some form of sorption onto solid or by transfer to another phase. L i C l is considered the least sorbing tracer available. The percentage of mass of tracer recovered from the columns is given in the Table 5.2. It can be seen from the data that a very high percentage of tracer was sorbed into the refuse. The long tails of the tracer curves are due to the tracer desorbing from the refuse and was consistent for all the tracer curves. It could be ideal if one could do the tracer experiments until after the desorption is completed and all the tracer mass is completely recovered.  Then using these data  63  Chapter 5. Results and Discussion  estimation of the part of the tracer curve responsible for sorption and desorption would make it possible to find the actual tracer curve due to the flow characteristics of the refuse column. Such a curve will give an accurate estimate of the t and cr where t would 2  give the mean H R T . When obtaining complete tracer curves are impossible one could look at the early part of the tracer curve to be due to the real hydraulics of the columns and the tail end of the curve to be due to sorption and desorption of the tracer. But the question "where to cut off the tracer curve to get a fair estimate of the actual HRT?" will arise. A wrong cut off point will give wrong HRTs for the columns. H R T of an ideal plug flow reactor is defined by the Equation 2.1. Flow through a plug flow reactor does not follow this idealized flow pattern even in chemical reactors. Nevertheless, H R T is defined by the Equation 2.1 for chemical reactors as well as for bio-reactors. It is used extensively as an operational parameter; a parameter which has been able to differentiate between flow conditions, which has been proven to be related to the performances of the reactors.  Also it has facilitated the design of the reactor  configurations to meet required performances. In these, absolute correct values for H R T were not necessary. Plug flow in a landfill could be far from ideal. Due to all these above mentioned reasons the author looked at the tracer curve in the following way.  The peak of the  tracer curve represents the time when the maximum number of particles reached the bottom of the lysimeters. Also either sides of the maximum concentration represents a high percentage of the tracer recovered. All the tracer curves demonstrated a consistent pattern. Therefore the time of the peak was chosen as the H R T of the columns. Absolute correct values for H R T are not necessary whereas a consistent means of measuring a difference in H R T is. Table 5.3 shows the predicted HRTs and actual HRTs taken from the tracer curves. Figure 5.6 shows the distribution of the observed HRTs.  64  Chapter 5. Results and Discussion  Column  # 1 3 4 2 7 10 13 16 18 5 8 9 6 15 17 11 12 14  Predicted HRT (day) 60 60 60 35 35 35 35 35 35 120 120 120 200 200 200 18 18 18  From the Tracer Curve Observed H R T (day) 60 60 60 16 23 36 36 16 20 87 120 145 200 190 215 16 18 16  Mean H R T (day) 60 60 60 25 25 25 25 25 25 117 117 117 200 200 200 17 17 17  Table 5.3: Comparison of Predicted and Observed HRTs  It can be seen from the results that the predicted H R T is close to the peak of the tracer curve, if not the same, for most lysimeters. These results show that the Equation 5.2 appears to predict the HRT reasonably well in the lysimeters. This can be extended to landfills. Water holding capacity is the field capacity of the landfill. Since most modern landfills keep records of the quantity of the refuse deposited, composition of the refuse and landfill cross sections, field capacity of the site can be estimated. Therefore, H R T for the landfill for different rainfall patterns can be calculated using Equation 5.2, once the landfills have been fully wetted.  65  Chapter 5. Results and Discussion  The first tracer curve for column 16, shown in Figure 5.7, gave an H R T of 22 days. From the tracer curve in Figure 5.2, column 16 has a peak concentration at 16 days. Also, a second tracer study was done for columns 7 and 10. Figure 5.8 shows the comparison of the tracer curves for these two columns at two different stages of decomposition. When the tracer study was done for the first time in column 16, the refuse was fairly new. By the time the second tracer study was started, the refuse has decomposed to some extent. From the tracer curve for column 10 it is seen that with decomposition H R T decreased from 36 days to 30 days. The tracer curves for column 7 shows that the peak concentration occurred at the same time as before. But the spread of the curve towards the left suggests reduction of retention time for some of the infiltrating water. Water holding capacity (field capacity) of the refuse decreases with decomposition. Therefore, according to the Equation 5.2, H R T decreases.  This argument is strengthened by the  tracer curves for 6 different columns which have the same flow rate (Figure 5.2). Columns 2, 16 and 18, that have high gas production, fall close together and show lower HRTs than columns 10 and 13 which had very low gas production and were in the very early stages of decomposition at the time of the tracer study. These observations indicate that the H R T decreases with the decomposition of the refuse. This is in accordance with the Equation 5.2, as S decreases with the decomposition of the refuse.  Chapter 5. Results and Discussion  30  66  T  Time (day) Figure 5.1: Tracer Response Curve for HRT=18 days  25  T  100 Time(day) Figure 5.2: Tracer Response Curve for HRT=35 days  67  er 5. Results and Discussion  25  T  Time(day) Figure 5.3: Tracer Response Curve for HRT=60 days  25  x  Time (day) Figure 5.4: Tracer Response Curve for HRT=120 days  68  Chapter 5. Results and Discussion 25 -r  Time (day)  Figure 5.5: Tracer Response Curve for HRT=200 days 250  T  0 -I 0  1  1  50  100 Predicted HRT (day)  :  1 150  Figure 5.6: Comparison of Observed HRTs  1 200  Chapter 5.  35  69  Results and Discussion T  Time (day) Figure 5.7: Tracer Response Curve for column 16  100  Time(day) Figure 5.8: Comparison of Tracer Response Curve for Columns 7 and 10 at Different Stages of Decomposition (a is for the second tracer study)  70  Chapter 5. Results and Discussion  5.3  General Characteristics of Landfill Gas (Phase I)  Characteristics of gas in landfills are affected by many environmental parameters. This research was aimed at determining the effects of H R T on landfill leachate and gas characteristics. Methane production rates in the columns are shown in Figures 5.9 - 5.14. These show the gradual increase and then decrease of the gas production which occurs in a normal landfill.  This trend was expected as discussed in Section 2.7.  Shown in  Figures 5.15 - 5.20 are cumulative CH4 production in the columns, which also show the gradual decrease in methane production. Figures 5.21 - 5.38 show the composition of gas in the columns throughout the study period.  These show the gradual increase in CH  4  concentration.  Composition of gas  was different from column to column. CH4 concentration in the columns ranged from 30 - 55% at the end of preliminary runs. After the columns were filled, they were seeded with anaerobic digester sludge.  This gave the refuse a good start in methanogenesis.  All the columns were at the start of the decomposition stage III (refer Figure 2.4) with respect to waste degradation stages except column 16 which was in the latter part of the decomposition stage III. No definite relationship was observed between gas production rate and the composition of gas in the columns at the beginning of the experiments (phase I). But with time towards the end of phase I, when the CH4 concentration increased, gas production increased. Figures 5.39 - 5.44 show the gas production rates for the columns. Gas production rates and gas compositions were different from column to column even with great care taken to produce identical refuse columns. In setting up the experiment, and after adding anaerobic digester sludge, all of the columns were sealed except for exit gas tubes to prevent air entry. As stated earlier, the exit gas tubes were connected to wet gas meters as they were calibrated. Columns 16, 7, 18 and 1 were the first columns to be connected. A l l but 10 and 13, were connected over the next period of two weeks.  71  Chapter 5. Results and Discussion  Columns 13 and 10, because of mechanical problems, were connected about 6 weeks after the first group. Once the gas meter was connected to a column it became completely sealed against air entry. This was not considered to be that significant since the tubes were only 5 mm in diameter and 1.5 - 4 m long. With the exit flow of gas produced in the column, diffusion of 0  was considered negligible. However, after being connected to  2  a gas meter, the pressure in the column builds up until it is able to push a 2 inch water column in the gas meter. This increase in pressure appears to assist the gas production. This was speculated from the observations that column 16 being the first to be connected had the highest gas production and columns 10 and 13, being the last to be connected, had the lowest gas productions. During the experiments it was observed that increasing amounts of C0  2  were dissolved  in leachate with increasing infiltration rates. Therefore the amount of gas produced is different from the amount of gas measured through the meters. very small compared to that of C0 . 2  Solubility of CH4 is  As such CH4 production rates (calculated from  measured CH4 concentration and measured gas production rates) were considered to be a better parameter for comparisons than the estimated total gas production rates (addition of estimated C0  2  dissolved and measured gas production). Estimates of total  gas production were done for those columns with lower dissolved solids and are presented in Appendix A. In addition inaccuracies that would arise in such estimates for the rest of the columns are discussed.  72  Chapter 5. Results and Discussion  12000  10000 + -a  o  8000  6000 +  o  CL I  4000  X  o  2000  50  100  150 200 Time (day)  250  300  350  12000 Phase IV  10000 ST  "O  c o fo =  8000 V 6000  O  4000 + o  2000 ¥  300  350  400  450 500 Time (day)  550  Figure 5.9: Methane Production Rate in Columns 1-3  600  300  350  400  450  500  550  Time (day) Figure 5.10: Methane Production Rate in Columns 4-6  600  74  Chapter 5. Results and Discussion 10000 -r  Phase I  9000 -8000 -%  7000 +  "D  -§ c o  6000  0  "a 2 a.  x o 1  50  100  150 200 Time (day)  250  300  350  Phase I  ro -o o 0  n  TJ  2 D. •ST 1  X  o  300  +  350  400  +  450 500 Time (day)  +  550  Figure 5.11: Methane Production Rate i n Columns 7-9  600  75  Chapter 5. Results and Discussion Phase I  3000  Phase  2500 +  5 2000 c 0  'o  1500  3 TJ  2 1  X  1000 4-  o 500  50  100  150 200 Time (day)  250  Phase IV  4500 T  300  350  300  350  400  450 500 Time (day)  550  Figure 5.12: Methane Production Rate in Columns 10-12  600  76  Chapter 5. Results and Discussion 4000  Phase  Phase I  3500 •13 -*-14 -c—15 ~  3000  CD  E 2500  50  100  150 200 Time (day)  300  250  350  Phase IV  300  350  400  450 500 Time (day)  550  Figure 5.13: Methane Production Rate in Columns 13-15  600  7000 -r 6000 4-  Phase IV  a 5000 c o 4000 + o  2 Q.  X 2000 O 1000 T  0 300  350  400  450 500 Time (day)  550  Figure 5.14: Methane Production Rate in Columns 16-18  600  78  Chapter 5. Results and Discussion  Figure 5.15: Cumulative Methane Production in Columns 1-3  Time (day) Figure 5.16: Cumulative Methane Production in Columns 4-6  79  Chapter 5. Results and Discussion  Time (day) Figure 5.17: Cumulative Methane Production in Columns 7-9  Time (day) Figure 5.18: Cumulative Methane Production in Columns 10-12  80  Chapter 5. Results and Discussion  Figure 5.19: Cumulative Methane Production in Columns 13-15  Time (day) Figure 5.20: Cumulative Methane Production in Columns 16-18  81  Chapter 5. Results and Discussion 90  T  HRT = 60 days  13 days •CO-2 •0-2 •N-2 •CH-4  i —  100  200  300 400 Time (day)  500  —  600  700  Figure 5.21: Composition of Gas in Column 1  100  200  300 400 Time (day)  500  Figure 5.22: Composition of Gas in Column 2  600  700  82  Chapter 5. Results and Discussion 90 - r  Figure 5.23: Composition of Gas in Column 3 90 - r 80 -- H RT = 35 days  H RT = 60 days  13 days  Time (day) Figure 5.24: Composition of Gas in Column 4  Chapter 5. Results and Discussion 90 13 days  300 400 Time (day)  100  Figure 5.25: Composition of Gas in Column 5  13 days  100  200  300 400 Time (day)  500  Figure 5.26: Composition of Gas in Column 6  600  84  Chapter 5. Results and Discussion 80  HRT = 35 days  70 + •CO-2 •0-2 •N-2 •CH-4  20 + 10  100  200  300 400 Time (day)  500  600  700  Figure 5.27: Composition of Gas in Column 7  HRT = 35 days  100  HRT = 120 days  200  300 400 Time (day)  13 days  500  Figure 5.28: Composition of Gas in Column 8  600  700  85  Chapter 5. Results and Discussion 90  ao +  H R T  =  3 5d a  y  s  H R T = 1 2 0  da  y  fl  100  200  300  13 days  s  •CO-2 •0-2 •N-2 •CH-4  H  H tt'^B  400  500  600  H-  700  Time (day)  Figure 5.29: Composition of Gas in Column 9  HRT = 35 days •CO-2 •0-2 •N-2 •CH-4  100  200  300 400 Time (day)  500  Figure 5.30: Composition of Gas in Column 10  600  700  86  Chapter 5. Results and Discussion 90  T  HRT = 35 days  100  HRT = 18 days  200  300 400 Time (day)  13 days  500  600  700  600  700  Figure 5.31: Composition of Gas in Column 11  100  200  300 400 Time (day)  500  Figure 5.32: Composition of Gas in Column 12  Figure 5.33: Composition of Gas in Column 13  HRT =18 days  100  200  300 400 Time (day)  13days  500  Figure 5.34: Composition of Gas in Column 14  600  700  Chapter 5.  Results and Discussion  88  Time (day) Figure 5.35: Composition of Gas i n C o l u m n 15  100  200  300  400  500  Time (day) Figure 5.36: Composition of Gas i n C o l u m n 16  600  700  Chapter 5. Results and Discussion  89  Time (day) Figure 5.37: Composition of Gas in Column 17  Time (day) Figure 5.38: Composition of Gas in Column 18  Chapter 5. Results and Discussion  20000 T  Phase I  Phase II  Time (day)  Phase  18000  300  350  Phase  400  450  500  Time (day)  Phase IV  550  600  Figure 5.39: Gas Production Rates in Columns 1-3  650  91  Chapter 5. Results and Discussion  16000 -r  Phase I  Phase  14000 o 12000 TJ  50  16000  100  Phase II  150 200 Time (day)  250  300  350  Phase IV  Phase  14000 -§ 12000 f 10000 4£  8000  TJ  6000 +  o g  CL  K D  CD  4000 42000 4-  300  350  400  450 500 Time(day)  550  Figure 5.40: Gas Production Rates in Columns 4-6  600  650  92  Chapter 5. Results and Discussion  Phase I  Phase  20000  50  100  Phase II  20000  150 200 Time (day)  250  300  350  Phase IV  Phase  16000 >>  CD T3  S12000 T c o P 8000 +  T3  CO CO  O 4000  300  350  400  450 500 Time (day)  550  Figure 5.41: Gas Production Rates in Columns 7-9  600  650  93  Chapter 5. Results and Discussion  Phase I  Phase II  8000 7000 + co T3  6000  5000 o « 4000 -a p  CO O 2000  50  100  150 Time (day)  200  250  350  Phase IV  Phase  8000 -r  300  ro 2000  300  350  400  450 500 Time (day)  550  Figure 5.42: Gas Production Rates in Columns 10-12  600  650  94  Chapter 5. Results and Discussion  50  100  150  200  250  350  300  Time (day)  Phase IV  8000  13  7000  14  o 6000  15  TJ  E 5000 + S 4000 4-  o  D TJ  g  3000  al  CO 2000 D  0  1000 +}  300  350  400  450  500  550  600  Time (day) Figure 5.43: Gas Production Rates in Columns 13-15  650  95  Chapter 5. Results and Discussion  Phase  Phase I 12000 > 10000 TJ  c o o  8000 6000  TJ  o CO  4000 4-  o  o  2000  50  100  150 200 Time (day)  250  o  -K-16  10000  \  TJ  c  8000  350  Phase IV  12000 ->:  300  Phase III for  -*-17  Phase III for  W  -0-18  W  16 & 18  17  o TJ  6000  TJ O  a. CO  o O  4000 2000 + 1  300  350  —I  400  1  1  450 500 Time (day)  H  550  Figure 5.44: Gas Production Rates in Columns 16-18  1  1  600  650  96  Chapter 5. Results and Discussion  5.3.1  Methane potential of the Refuse Columns  Cumulative CH4 production by the end of the experiments for the columns are tabulated in Table 5.4.  They ranged from 16 - 76 L / k g of dry refuse.  CH4 potential for these  columns is 470 L / k g of dry composite refuse based on the available organics in the columns and assuming organics are 100% biodegradable. The potential methane production from the refuse columns was estimated based on an assumed stochiometri. From Emcon Associates (1980); empirical formulae for food waste and non food organic wastes are CieH^OgN  and  respectively.  CZOZHZMOIZSN  The mass of CH4 that can be produced assuming 100% conversion of the given constituent to CO2, CH4 and NH3 is given by the Equation 5.5 (Parkin and Owen, 1986). CHON n  a  b  c  + [n-  a/4 - 6/2 + 3c/4]# 0  -  2  [n/2 - a/8 + 6/4 + 3c/8]C0 + [n/2 + a/8 - 6/4 - 3c/8]C*H •+ cNH 2  4  Using the empirical formula for food waste C H 70 N ie  2  8  +  6 H  2  0  S  -»• 7 C 0 + 9 C # + 4  NH  3  361 g of food waste  —> 9 moles of CH4  From P V  = nRT  CH4  (5.5)  and the Equation 5.5;  CIQ,H270 N  2  3  potential at 2 0 ° C from 1 kg of food waste = (9X0.082X293/0.361) liters = 600 liters  Using the empirical formula for non-food organic waste C203^334Oi38^V and the Equation 5.5; C 03 #334Oi3 iV 4- 51.25# 0 -> 94.6C0 + 108.4C# + 2  8  4992 g of non-food organic waste  2  2  4  NH  S  —> • 108.4 moles of CH4  97  Chapter 5. Results and Discussion  From P V  nRT  CH4 potential at 2 0 ° C from 1 kg of food waste  (108.4X0.082X293/4.992)  liters  521 liters Wet weight of paper  8X1.93 kg 15.44 kg  Wet weight of garden waste  8X1.2 + 4 kg  Total wet weight of non-food organics  29.04 kg  Dry weight of non-food organics  29.04X(l-0.36) kg 18.58 kg  CH4 potential due to non-food organics  18.58 X 521 9680 liters  Total wet weight of food waste in a column  8 X 2 kg 16 kg  CH  4  potential due to food waste  16 (1-0.36) X 600 liters 6144 liters  CH4 potential from refuse in one column  15824 liters  Total wet weight of non organics in the column  7.6 kg  CH4 potential from 1 kg of dry composite refuse  15824/(18.58+10.24+7.6 X 0.64) 470 liters  CH4 potential from 1 kg of wet composite refuse  15824/(29.04+16+7.6) 300 liters  CH4 potential from the anaerobic digester sludge was not included in the calculations. From these columns 3 -16% of the potential CH4 was recovered during 630 day period. Distribution of CH4 potential from food waste, garden waste and paper are 38.8%, 28.7%  Chapter 5. Results and Discussion  and 32.5% respectively.  98  Barlaz et al. (1989) observed that in their experiment very  little solid hydrolysis occurred during the early stages of the decomposition. It can be assumed that the CH4 produced is basically from the food waste. That even though CH4 production rates are decreasing in the columns, theoretically 95 - 75% (if the organics are 100% degradable) of the CH4 potential is still left in -the columns which will be slowly excercised with time. This is further discussed in Section 5.9. Table 5.5 compares CH4 production rates from this study with those of other studies. The range of ultimate methane yields observed is comparable with the other studies. CH4 production rates at the end of the study were still higher than the other studies in the Table 5.5 (except Barlaz et al., 1989). Therefore it is reasonable to expect that most of the CH4 potential will be exercised with time.  99  Chapter 5. Results and Discussion  Column  # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  Cumulative CH4 Produced (liters) 1451 2565 • 736 1447 2197 2128 2557 2528 1289 865 1084 838 710 832 1260 2203 539 1325  CH4 Produced liters per kg of dry composite refuse (m /tonne) 43 76 22 43 65 60 76 75 38 26 32 25 21 25 37 65 16 39 3  Table 5.4: Comparison of CH4 Produced from the Columns  Chapter 5. Results and  Source  100  Discussion  Annual rate of methane production (m /dry kg/yr.) 0.01-0.041* 0.018-0.12 (max) 0.0081-0.021 (range) 0.017 (control cell)  Ultimate methane yield (m /dry kg) 3  Comments  z  This work  0.016-0.076  Fawcett and Ham, 1986  0.032-0.090 (range) 0.071 (control)  Barlaz et al., 1989  0.087  Ehrig, 1991  0.078-0.11 (range)  0.29  MSW and anaerobic digestor sludge; range for 18 cells Mountain View, California, U S A controlled landfill (field project) Laboratory incubation of fresh refuse in 2L containers for 111 days at 41°C with leachate recycle and neutralization; water added to 73% (wt/wt) Laboratory incubation of fresh refuse mixed with composted refuse (2:1) in 120 L containers for 300 to 400 days at 30°C with leachate recycle; water added to 65% (wt/wt)  0.022 (max)  Jenkins and Pettus, 1985  Laboratory incubation of landfill cores (15 cm dia. X 76 cm long at 37°C; assuming 50% CH from total gas generation of 0.043 m /(drykg)/yr 4  z  0.005  Wreford, 1995  Burns Bog landfill, Vancover, B.C., Canada  Table 5.5: Comparison of CH Yields and Annual Production Rates; *- CH rate for the last sampling (adapted from Bogner and Spokas, 1993) 4  4  production  Chapter 5. Results and  5.4  101  Discussion  Effect of H R T on Landfill Gas Characteristics (Phases II, III and IV)  Composition of gas was affected by the H R T . Increasing H R T from 35 days resulted in a decrease in CH4 concentration. The opposite was observed in columns where H R T was lowered from 35 days. During phase III, when the HRTs were lowered even further (Table 4.4), CH4 concentration increased to fairly high values, (as high as 92% in column 18) with corresponding decreases in CO2 concentration.  Figure 5.45 shows the CH4  concentration versus HRT, at the steady state conditions. HRTs were controlled by controlling the infiltration rates in the columns. For the lowest HRT, 3 day, (column 18 in phase III) the infiltration rate was 11200 ml/day. In this column CO2 concentration was less than 8%. With high infiltration, CO2 produced will not be released to the gas phase resulting in higher CH4 concentration in the gas stream. If this was the only effect, gas production rates should decrease since part of the CO2 stayed in the leachate. But change in H R T did not change the gas production pattern other than the sudden increase shortly after switching HRTs (Figures 5.39 - 5.44). This sudden increase is due to displacement of gas by increased water inflow. Once the columns were adjusted to the new high water inflow, gas production rates fell back into the earlier trend; decreasing, increasing or steady. If the CO2 dissolved were estimated and added to the gas production measured it would show an increase in overall gas production. According to the literature, CO2 partial pressure affects methanogenesis (Hansson, 1979; Hansson, 1982; Hansson and Molin, 1981a,b). The removal rate of acetic acid was significantly affected by the increase of carbon dioxide partial pressure, while butyric acid removal, which does not produce carbon dioxide, was not affected (Hansson, 1979; Hansson, 1982; Hansson and Molin, 1981a,b).  In their experiments at lower CO2 partial  pressures (0.2 atmospheric), acetate degradation was four times higher than that at 1  102  Chapter 5. Results and Discussion  atmospheric C 0 2 - The conversion of acetic acid to methane is by far the most important part of the methane forming process (about 70%) (Christensen and Kjeldsen, 1989). A decrease in CO2 partial pressure should enhance methanogenesis (Hansson, 1979; Hansson, 1982; Hansson and Molin, 1981a,b). Therefore, the increase in CH4 concentration observed during low HRTs could also be due to the enhanced methanogenesis. Theoretically, when there is no water flowing one would expect the CH4 concentration to decrease since all the CO2 produced is released to the gas phase. Data showed that the CH4 concentration at steady state dropped after the pump was stopped (i.e., no infiltration). CH4 concentration in phase IV can be considered as CH4 concentration of gas produced (no CO2 dissolved in infiltrating water). In phases I, II and III, measured CH4 concentrations are higher than the CH4 concentration of gas produced due to CO2 being dissolved in different rates of infiltrating water (230 ml/day - 11200 ml/day). A small increase in CH4 concentration (from the CH4 concentration before the H R T was lowered in phase III) was seen in columns 1, 2, 3, 5, 6, 8, 9, 15, 16 and 17 (Table 5.6). Columns 7 and 10 which can be considered as controls, decreased their CH4 concentration after the pump was stopped. This is expected, since C0  2  that would have dissolved  in leachate is in the gas stream. Also, for columns 11, 12 and 14, there was a decrease in CH4 concentration. These three columns had HRTs of 18 days (2300 ml/day), which is fairly low compared to the other columns at that time and had comparatively high CH4  concentration due to CO2 being in infiltrating water during phase II also. A base  amount of CH4 cannot be found for these three columns. Column 15 did not go through a period of low CO2 partial pressure. No improvement in methanogenesis was expected in this column. Data shows that there was an increase in methanogenesis.  Column 15  started to increase its pH with a decrease in VFAs by the end of phase II. Increase in CH4 is due to the enhancement of methanogenesis. When the H R T was higher than 60 days (600 ml/day) there was no significant effect on  103  Chapter 5. Results and Discussion  Column  # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  Before Phase III Infiltration CH (ml/day) content (%) 600 52 1150 54.8 600 52.2 600 54.8 330 49.7 230 53 1150 57.8 330 52.9 330 53.7 1150 59 2300 60.8 2300 65.2 1150 57.4 2300 63.6 230 50.2 1150 54 230 48.1 1150 59 4  Phase III infiltration (ml/day) 2800 2800 2800 2800 2800 2800 1150 2800 2800 1150 2800 2800 2800 2800 230 5600 2800 11200  CH content after Phase III (%) 53.6 55.8 55.2 54.8 54.9 55.6 55.8 55.3 55.8 56.1 57.7 54.8 55.8 55.9 54.4 56.2 56.5 56.5 A  Remarks  increased increased increased increased increased increased decrease explained increased increased decrease explained m.h.i.b.v. m.h.i.b.v. m.h.i.b.v. m.h.i.b.v. increase explained increased increased decrease unexplained  Table 5.6: Comparison of CH concentration before Phase III and after Phase IV; m.h.i.b.v. =must have increased from the base value 4  CH4 concentration (Figure 5.45). HRTs higher than this were achieved by even smaller infiltration rates. When the CO2 is produced in the bacterial cells it will start moving away from the cell and will be in water as long as the carbonic acid system allows. With lower flow rates (higher concentrations of dissolved CO2 will shift the equilibrium to the left) most of the CO2 will be released into the gas stream. Lower flow rates accompanied by the higher concentrations of dissolved constituents further decrease the potential of the CO2 to be in the carbonic acid system. As a result of the high CO2 partial pressure, there was no increase in methanogenic activity.  104  Chapter 5. Results and Discussion  Comparison of CH4 production rates is difficult due to different decomposition histories of the columns. However some observations are possible as there are sets of columns with similar cumulative methane production prior to the changes in HRTs. As shown in Figure 5.46 columns 2, 5 and 6 had similar CH  4  production during phase I. At the end  of phase II, column 2 had the highest methane production followed by column 5 in the order of increasing H R T . Similar comparison between columns 15 and 1 which had the same CH  4  production also showed that at the end of phase II lower H R T (column 1)  had higher CH4 production. Another pair of columns that had similar CH4 production during phase I is 7 and 8 (Figure 5.17). H R T of column 8 was increased to 120 days while column 7 was not changed.  By the end of phase II column 7 had higher CH4  production than column 8. Columns 12 and 13 showed the same effect (Figure 5.48). Column 12 started CH4 production earlier than column 13 but they both had similar CH4 production towards the end of phase I and at the beginning of phase II. Column 12 showed higher CH4 production (lower H R T than column 13) towards the end of phase II which also suggests that lower H R T increased the methanogenesis.  For all sets lower  H R T columns had increased methanogenesis relative to the higher H R T columns. In summary when there were similar phase I starting rates, CH4 production was higher for columns with shorter HRTs.  105  Chapter 5. Results and Discussion  Figure 5.46: Comparison of Cumulative CH Production of Columns 2, 5 and 6 4  106  Chapter 5. Results and Discussion  Time (day) Figure 5.47: Comparison of Cumulative CH Production of Columns 15 and 1 4  Figure 5.48: Comparison of Cumulative CH4 Production of Columns 12 and 13  r Chapter 5. Results and Discussion  5.5  107  General Characteristics of Leachate (Phase I)  Leachate was characterized for V F A , C O D , total organic carbon (TOC), volatile solids, dissolved solids, total solids, chlorides, NHo, — N, T K N , zinc, iron, sodium, pH, specific conductance and alkalinity. During phase I, when all the columns had similar HRTs of 35 days (infiltration rate = 1150 ml/day), all the parameters analyzed showed a similar pattern except metals and pH. At the beginning, concentrations were different for all the columns but within 3 months they all converged to smaller similar values. pH values in all the columns were between 5.2 and 5.5. After about two months, pH in some columns started to decrease and some started to increase. These are discussed in detail in Section 5.6.1. Metals (iron, sodium and zinc) had very different concentrations and showed random patterns during phase I. These are discussed in detail in Sections 5.6.9, 5.6.10 and 5.6.11.  5.6  Effect of H R T on Landfill Leachate (Phase II and III)  Leachate characteristics were affected by the HRTs. During phase II, HRTs were changed from 35 days to higher values and lower values. Higher HRTs (in most of the columns) resulted in increasing the concentrations in all the constituents except pH. Lower HRTs resulted in decreasing all constituent concentrations except pH. These are discussed in the following sections under each parameter. During phase III, HRTs were decreased to very low values (13, 6 and 3 days). This resulted in decreasing all the constituent concentrations except pH and alkalinity. Some columns decreased their pH and some columns increased their pH. With respect to alkalinities, some columns maintained steady values, others decreased.  Chapter 5. Results and Discussion  5.6.1  108  pH  Figures 5.49 - 5.53 show the change in pH with time, during different phases of the experiment. It can be seen from these figures that p H ranged from 4.6 to 7. There was CH  4  production in all these columns even if pH was below 5.5. These pH values are  typical for lysimeter studies, whereas for full scale landfills the range of pH observed are typically higher (Table 2.3). At the beginning of the experiments pH in all the columns were between 5.2 and 5.5. After about two months when the leachate constituent concentrations decreased, the pH started to increase for high CH4 production columns and decrease for the others. Columns with high CH4 production (cumulative above 130 L) had a trend of increasing pH up to about 6.5 to 7.5 during the phase II irrespective of HRTs. Columns with lower cumulative CH4 production than 130 L responded to changes in H R T . For columns 1, 3 and 4, where HRTs were increased to 60 days, the pH continued to decrease for some time and only started to increase with increasing CH4 production (VFAs are consumed). In columns 15 and 17 (HRT - 200 days), pH kept decreasing until the end of phase II. Decrease in pH coincided with the increase in V F A concentrations. When the VFAs started to decrease, the p H of the two columns started to increase slowly. Column 6 where H R T was also increased to 200 days started to show a pH increase soon after changing the HRT. This column had high CH4 production (cumulative 154 L). Therefore, decrease in VFAs was observed shortly after starting phase II and hence the increase in pH. CH4 production in columns 11, 12 and 14 was low (cumulative 58, 26.5 and 38.5 L respectively by the end of phase I) and each had a pH of 5.3 when their HRTs were lowered to 18 days. Their pH started to increase shortly after (except 11 which took a little longer than others) and reached pH values of above 5.8 by the end of the phase II. Columns 10 and 13 (cumulative CH4 production 23 and 27 L), where HRTs were not  Chapter 5. Results and Discussion  109  changed, did not change their pH trend (they had a decreasing trend and was steady after starting phase II) until they reached steady state conditions with respect to gas composition. After they reached 50% CH4 concentration, the pH started to increase. Columns 12 and 13 both had the same CH4 production. Column 12 had a decrease in H R T and column 13 did not change. Increase in pH in column 12 is possibly due to the decrease in H R T which is favorable for methanogenesis. During phase III the HRTs of all the columns (except 7, 10 and 15) were dropped to 13, 6 and 3 days from various HRTs ranging from 18 to 200 days. Infiltration rates adopted to get HRTs of 13, 6 and 3 days were 2800, 5600 and 11200 ml/day. By the end of the phase II, pH of all the columns that had high CH4 productions were between 5.7 and 7.2. Also columns 11, 12 and 14 which did not have high CH4 production as the above columns but had low HRTs, had pH in the above range. During phase III, when the HRTs were lowered, all the columns that had pH values above 5.8 (columns 2, 4, 5, 6, 7, 8, 9, 11, 12, 14, 16 and 18) showed a pH decrease within a week, except column 11 and 14 where there was no change. These columns (2, 4, 5, 6, 7, 8, 9, 16 and 18) except 11, 12 and 14 had established high CH4 production by the end of phase II. Also the C0  2  concentration in the gas phase decreased. Evidence that the  inorganic carbon levels also increased in these columns, suggests that some of the  C0  2  was dissolved in leachate. This could account for the decrease in pH. Columns 11, 12 and 14 already had a fairly low H R T of 18 days. Their pH values were 5.8, 5.9 and 5.9 respectively. Columns 12 and 14 had established pH above 5.8 for about three months, whereas column 11 had been increasing its pH from 4.9 and just entered the above range at the end of phase II. It kept increasing regardless of the change in HRT. Its very active methanogens are indicated by the fast rate of decreasing V F A during the last two months of phase II. Leachate from columns 1, 3, 13 and 17 which had pH below 5.4, started to increase in  Chapter 5. Results and Discussion  0  50  100  150  200  110  250  300  350  400  450  500  550  Time(day) Figure 5.49: Change in pH in Columns 11, 12 and 14 pH when HRTs were decreased to 13 days. These columns had high V F A concentrations (830, 800, 615 and 3375 m g / L respectively) at this time. So the dilution of VFAs is the likely reason for increasing pH. This same trend of increasing pH (when H R T was decreased) was observed in columns 11, 12 and 14 which had higher VFAs when their HRTs were decreased during phase II. In summary, the effect of H R T on pH depended on the stage of decomposition (CH4 production) and the leachate V F A concentration at the time. When the H R T was increased in established high CH4 producing columns, the pH kept increasing since the V F A was being consumed. The pH in low CH4 producing columns decreased since the V F A concentrations increased due to concentration. When the H R T decreased, high CH4 producing columns reduced the pH due to the shift in carbonic acid system. Low CH4 producing columns, which had higher V F A concentrations, increased their pH due to the dilution of VFAs.  111  Chapter 5. Results and Discussion  Figure 5.50: Change in pH in Columns 2, 7, 10, 13, 16 and 18  HRT = 60 days  HRT = 35 days  HRT=13days •1 •3 •4  0  50  100  150  200  250 300 Time(day)  350  400  450  Figure 5.51: Change in pH in Columns 1, 3 and 4  500  550  112  Chapter 5. Results and Discussion  7"  HRT = 120 days  HRT = 35 days  13 days  6.5 --  ol 5.5  1  1  H  1  50  100  150  200  1  1  1  1  250 300 Time(day)  350  400  r—  450  1  1  500  550  Figure 5.52: Change in pH in Columns 5, 8 and 9  H RT = 35 days  50  100  150  ,  H RT = 200 days  200  250 300 Time(day)  350  13 days except 15  400  450  Figure 5.53: Change in pH in Columns 6, 15 and 17  500  550  113  Chapter 5. Results and Discussion  5.6.2  Volatile Fatty A c i d s ( V F A )  Figures 5.54 - 5.56 show the change in V F A with time. At the beginning of the research (phase I), V F A concentrations of the columns ranged from 23,000 - 45,000 mg/L. This is typical for a young landfill leachate. These leachates are referred to as young leachate at the beginning since the refuse was fresh. By the end of phase I (a period of 163 days), V F A concentrations decreased to a range of 1400 - 6200 mg/L. The columns with high CH  4  production showed a faster decrease in VFAs than the low CH producing 4  columns. During this period, the columns where HRTs were changed from 35 days to lower HRTs (columns 11, 12 and 14), continued reductions of V F A concentrations were observed. Columns where HRTs were increased, showed increases in V F A concentrations at the beginning but started to decrease later. Columns 15 and 17 where HRTs were increased to 200 days, showed increased VFAs up to a period corresponding to one H R T and then started to decline. In columns 5, 8 and 9 with H R T of 120 days VFAs increased for a short period of time and then started to decrease. Columns 1, 3 and 4 where HRTs were shifted to 60 days, VFAs increased for about 50 days before they started to decline. Column 6 with higher H R T (200 days) did not follow the above pattern. This column had very high CH4 production and, as such, the V F A was being consumed quickly. By the end of phase II, V F A concentration in columns 2, 7, 8, 9, 12, 14, 16 and 18 were very low (in the range 0-20 mg/L), while for the other columns, it fell into a range of 130 - 4250 mg/L. When HRTs were lowered to 13, 6 and 3 days, V F A concentrations of all the columns decreased very rapidly. This is expected due to dilution as well as due to increased methanogenesis. VFAs were analyzed in terms of acetic acid, propionic acid, butyric acid and valeric acid. During the early stages of the experiments butyric acid and acetic acid were  114  Chapter 5. Results and Discussion  dominant. With time the acetic acid portion increased. Towards the end of the experiments, where the concentrations were small, the only V F A detectable was acetic acid. Distribution of VFAs in all the columns are given in Figures 5.57 - 5.74. The VFAs in high gas producing columns fell off to negligible values midway during phase II. Other columns also decreased their concentrations towards the end of phase III. Therefore, in Figures 5.57 - 5.74 towards the end of the time axis, the concentrations are very small. Once the VFAs decreased to small values during the analysis the peaks of the response curves were sometimes not detectable, even if the presence of most of the V F A types were seen. Therefore, 100% acetic acid towards the end of time scale does not necessarily mean there were no other types of VFAs. No relationship was observed between H R T and the distribution of V F A types. During phase III when the C0  2  partial pressure decreased in the columns acetic acid concen-  trations should decrease faster than propionic acid since the C0  2  partial pressure affects  only acetic acid conversion but not the propionic acid (Hansson, 1979; Hansson, 1982; Hansson and Molin, 1981a,b). This could not be seen due to the low concentrations. Mass of V F A released to the environment are discussed in Section 5.7.  115  Chapter 5. Results and Discussion  Time (day)  Figure 5.54: Change in V F A in Columns 1-6  116  Chapter 5. Results and Discussion  60000 -r  Phase I  P III  Phase  4- 8000 50000 H-  40000 cn  -§ 30000 < LL  > 20000 10000 +  100  200 Time (daypO  400  500  Figure 5.55: Change in V F A in Columns 7-12  60000  Phase  50000 40000 -§ 30000 < u. > 20000 410000 4-  100  200  300 Time (day)  400  Figure 5.56: Change in V F A in Columns 13-18  500  117  Chapter 5. Results and Discussion  100%  & others ^ butyric • propionic • acetic  80%  60% c  CD O  S. 40% 20% 4\  0% I"!  1  |ii|H|ii|ii|H|ii|ii|ii|  11 I 11 I 111 111 11 I I • 111 1) I I 11 I 11  I j 11 111 I u I u I u I u I 1  o c M O o o c o ^ t o j o m ^ f o j o o c o c n c o - i -  Time (day) Figure 5.57: Distribution of VFAs in Column 1  100%  80%  3*  60%  B others • butyric • propionic • acetic  c  0-  40%  20%  0%  O  CM O r-  00 CD  ro  CM T  -  I  S -  c v i o i n ' d - c n o o c o c n O T 0 0 i - - ^ - C T ) C M r - T + C D 0 0 - i I  -  C  M  C  M  C  V  C  T  C  O  Time (day) Figure 5.58: Distribution of VFAs in Column 2  in  H—I  118  Chapter 5. Results and Discussion 100%  - T O  i  80%  S>  60%  S others butyric • propionic • acetic  c CD  E CD  Q.  40% 20%  0%  O  C  N  O  O  O  C  O  ^  C  V  I  O  l  O  '  S  -  C  O  O  O  C  O  C  n  C  O  '  t  -  Time (day) Figure 5.59: Distribution of VFAs in Column 3 100%  I I II 1  - I -  80%  ^  60%  c a> 0  1  40% 4] 20%  0%  o c x i o o o c o ^ - c v i o i n ^ - c n c n c o c n c o - i —D CM c v i i n o o i - ' f r O i C M i ' ^ ' d - c o c o - ! 1^ C Time (day) Figure 5.60: Distribution of VFAs in Column 4  B others & butyric • propionic • acetic  119  Chapter 5. Results and Discussion  100% TH  80% & others butyric • propionic • acetic  60% CD CD  o- 40%  20%  0%  |ii|ii|ii|ii|ii|ii|ii|H|ii|ii|ii|ii|ii|ii|ii|ii|H|U|  o c v i o c n c D ^ + c \ j O L n r j - o ) o o c o o 5 c o - i — • ^ r ^ o i c N j i n o o - t - r f c r i c \ i r ~ - ^ f c o Q O - i -  Time (day) Figure 5.61: Distribution of VFAs in Column 5  100%  80%  60%  El others El butyric  c  CD U  £  • propionic  40%  • acetic  20%  0% | l l | l l | l l | l l | l l | l l | l l | l l | l l | l l | t l | U | U | U | U | U | U | U | U | U | U | U | U | U |  o c M O o o c o - ^ - c v j o i n ^ t o o o c o e n c o T r r r ^ c n c v j i n o o - i - T i - c n c v i r ^ - ^ - c D c o T i - - i - - i - c M C M C \ J c o c o ' * ^ ' a - m  Time (day) Figure 5.62: Distribution of VFAs in Column 6  120  Chapter 5. Results and Discussion  S others • butyric • propionic • acetic  CD Q-  O  C MO  c o i o ^ t i M O i f l ' J c i i o o n f f l n ' O ) C M l O C D T - ^ - O ) < M l  s  - ' ^ t C D 0 0 - i -  Time (day) Figure 5.63: Distribution of VFAs in Column 7  100% TH  80%  C?  S others butyric • propionic • acetic  60%  c •  40%  20% -H  Time (day) Figure 5.64: Distribution of VFAs in Column 8  121  Results and Discussion  § • • •  others butyric propionic acetic  Time (day) Figure 5.65: Distribution of VFAs in Column 9  100% others ^ butyric  80%  propionic • acetic  60% c  Q) O  £  40% 20%  0%  |M|U|LI|U|U|U|U|U|Li[ll[ll|ll|U|U|U|U|U| O  OJ  O  — I  00 CO O  CM  S  |  |  c M O i n ^ c n c o c o c o c o - i -  | |JJ_|  ^ T - ^ c n c M i v . T i - c o o p T r iCM CM CM CO CO in  Time (day)  Figure 5.66: Distribution of VFAs in Column 10  Chapter 5. Results and Discussion  I  100% -m  122  80%  5 others  60%  • butyric  c  • propionic  CD  • acetic  E CD Q.  40% 20%  O  o  /o  jl 1,11,11111,11,11 jl I |l 1,1J 111 |l 1111 |LJLJ j L J ! |U|II|II|U|U|U|U|U|U|LI|U|U| O C N I O C D C O ^ C V J O U l ' f r C O C O C O O J C O i Ttr>-o)C\jLnoo-i-'!tc»cvji^'*cDoo-iTime (day) t  Figure 5.67: Distribution of VFAs in Column 11 100%  80%  3*  S others  60%  ^ butyric  c  • propionic  CD U  I  • acetic  40%  20%  0%  o c \ i o r o c o - * c M O i f i ^ c » c D c o o > c r > - ! • ^ r ^ c n c N j L n o 3 - i - ' ^ - c T ) C v i r ~ ' ^ - c o o o - i i - T - i - w t M c M n n ^ ^ ^ w  Time (day) Figure 5.68: Distribution of VFAs in Column 12  123  Chapter 5. Results and Discussion  100%  TB  80%  3*  ll  60%  c  5 others butyric • propionic • acetic  2 CD Q-  40% 20%  Q  III^IIIIIIIIII^^UIUIUILIIH^IJII^IIU^IU^IUIUIUIUIUIUIIIIIJIIJIU^IUIUI  0/O  O O J O O O C D ' a ' O J O L O ^ t C n o O O O C D C O T -  Time (day) Figure 5.69: Distribution of VFAs in Column 13  100% TB  5 others Ii butyric • propionic • acetic  o c j o c o c o ^ t c j o i n ^ f o j c o c o c n c o i • i - i - ' i - c v j c M C J c o c o T f ^ i - ' ^ - m  Time (day)  Figure 5.70: Distribution of VFAs in Column 14  124  Chapter 5. Results and Discussion  100%  T H  80% 5 • • •  60% tz  <D o  CD Q-  others butyric propionic acetic  40%  20%  0% I'  I'M  1 1 1 1 1 1 1 1 1 11  'l"l"l"l l u  11  11  11  11  11  11  11  I  I  I  o c N j o o o c D ^ c \ j o i n ^ - c » o o c o c n c o - i • ^ t ^ O T C \ i i n o D - i - - ^ c » C N j r ^ ^ c o o O ' i -  l"l  Time (day) Figure 5.71: Distribution of VFAs in Column 15  100%  80% S others  Ce 60%  • butyric  c  • propionic  o  • acetic  g. 40% 20%  0%  o c \ i o o o c o ' * o j O L n ' ! t c o o o 1 - 1 - 1 - C M C M C M C O C O  l"l"l"l  l"l"l  CD  T—  cn  Time (day) Figure 5.72: Distribution of VFAs in Column 16  co 00  iLO  125  Chapter 5. Results and Discussion  100%  T B  90% 80% -H 70%  S others E33 butyric • propionic • acetic  60% c  50%  a.  40%  CD O CD  30% 20% 10% 0%  11111111111111 11111111111U | U | U | U | U | U | U | U | II111111,1111J | LJ | U , U | U | U , U | LJ | o c \ i o o o c o ^ r c M O i f ) T r o > o o c o o 5 c o - i • ^ • t ^ c n i N m o o - i - t c n c u r ^ - ^ c D o o - i T - - T - i - c v j c M c \ i c o c 5 ^ t - ^ - ' ^ - u n Y  Time (day) Figure 5.73: Distribution of VFAs in Column 17  100%  T B  80% S others ES butyric • propionic • acetic  3" 60% c  CD O  rJ 40%  20% 0%  o c v i o o o c D ' j c v i o i n T f r o c o c o c n c o - i • ^ r ^ 0 5 C M i f ) o o - i - - > * o > c \ i r ^ ^ - c o o o - i -  Time (day) Figure 5.74: Distribution of VFAs in Column 18  126  Chapter 5. Results and Discussion  5.6.3  Chemical Oxygen Demand ( C O D )  Change in C O D for the columns are given in Figures 5.75 - 5.77. At the beginning of the experiments, C O D for the columns were in the range of 42,000 - 62,000 mg/L. C O D for all the columns followed the same pattern as V F A during all three phases except column 15 during phase III. H R T of column 15 was not changed during phase III. During this period column 15 had its peak in CH production rate. This coincided with the increase 4  in pH and rapid decrease in V F A . But the rate of decrease in C O D did not appear to change. Mass of C O D released to the environment is discussed in the Section 5.7.  Time (day) Figure 5.75: Change in C O D in Columns 1-6  127  Chapter 5. Results and Discussion  Phase I  P HI T 14000  =B> 40000 E O 30000 O  0  50  100  150  200  250 300 Time (day)  350  400  450  500  550  Figure 5.76: Change in C O D in Columns 7-12  60000  Phase I  P III  Phase  50000 40000  Q O o  30000 20000 + 10000 +  100  200  300 Time (day)  400  Figure 5.77: Change in C O D in Columns 13-18  500  16000  Chapter 5. Results and Discussion  5.6.4  128  Total Organic C a r b o n ( T O C ) and Inorganic C a r b o n (IC)  Changes in T O C for the columns with time are given in Figures 5.78 - 5.80. T O C in all the columns during phase I decreased very rapidly. When the HRTs were changed (phase II and phase III), T O C followed the same pattern as V F A . The mass of T O C released to the environment is discussed in the Section 5.7. Figures 5.81 - 5.83 shows the change in IC concentrations in the columns. IC concentrations followed a different pattern. During the early stages of the research, the leachate was very strong and was necessarily diluted for analysis. When samples are diluted, IC can be lost and the results are not accurate. Therefore the initial IC concentrations were not taken into consideration in data interpretation. After about 2 months when leachate concentrations had decreased, IC was analyzed using undiluted samples. After this change in analysis, the IC concentration also had a decreasing pattern for some time and started to increase towards the end of the phase I. When the HRTs were changed (phase II) IC showed no relation to HRT. During phase III when HRTs were decreased to 13, 6 and 3, ICs in all the columns increased to a range of 100 - 300 mg/L. During phase III extra care was taken to limit the dissipation of C0  2  dissolved by covering the sampling vials with tape until analysis.  This must have added to some extent to the increase in IC. This can be seen from the increase in IC in columns 7, 10 and 15 whose HRTs were not changed during phase III. But the increase in other columns was higher than these columns. The decreasing trend of IC is due to leaching out of IC from the landfill mass. With the increase in gas production in the columns an increase in dissolved CO2 in the leachate is expected. This would increase the IC in the leachate.  Chapter 5. Results and Discussion  129  Time (day) Figure 5.78: Change in T O C in Columns 1-6  0  100  200  300  400  Time (day) Figure 5.79: Change in T O C in Columns 7-12  500  130  Chapter 5. Results and Discussion  T 6000  r 5000  200  100  300 Time (day)  400  500  Figure 5.80: Change i n T O C i n Columns 13-18 Phase I  ,  Phase II •1 •2 •3 •4 •5 •6  50  100  150  200  250 300 Time(day)  350  400  Figure 5.81: Change i n I C i n Columns 1-6  450  500  550  Figure 5.82: Change in IC in Columns 7-12  Figure 5.83: Change in IC in Columns 13-18  Chapter 5. Results and Discussion  5.6.5  132  Alkalinity  Figures 5.84 - 5.86 shows the change in alkalinity of the columns during the study period. Initial leachate (phase I) had alkalinities in the range 6800 - 12000 mg CaCOz/L.  With  time, the alkalinity concentrations decreased until the end of phase I. With the changed HRTs in phase II, irrespective of the HRTs, high CH4 production columns (2, 5, 6, 7, 8, 9, 16 and 18) maintained an alkalinity above 500 mg/L. An increase in alkalinity is expected with the consumption of V F A (Christensen and Kjeldsen, 1989). In columns with low CH4 production, alkalinities kept decreasing. Exceptions to these were columns 15 and 17, where an alkalinity of above 600 m g / L was maintained until the end of phase II. This could be due to the concentration of alkalinity by increased H R T . By the end of phase II, alkalinities of the columns which had high CH4 production and high H R T (columns 5, 6, 8 and 9 had HRTs of 120, 200, 120 and 120 respectively) were in the range 740 - 1060 mg CaCO^/h.  By the end of phase II, alkalinities of the columns 2, 7, 16 and  18 which had higher CH4 production and lower H R T (35 days) were 540, 495, 340 and 460 mg CaCOz/L  respectively. These were in parallel with their CH4 production rates  at the time; 4840, 4050, 3160 and 3280 ml/day respectively. Columns 5, 6, 8 and 9 could maintain the alkalinity produced by methanogenesis due to their lower infiltration rates than columns 2, 7, 16 and 18. During phase III, when the HRTs were lowered to 13, 6 and 3 days, columns that had high alkalinities decreased in concentration showing the effect of dilution with high infiltrating water. But the columns that had low alkalinities around 200 mg/L, did not change due to dilution. It was observed that there is a definite relationship between pH, H R T and alkalinity. This is shown in Figure 5.87. Lower HRT's maintained a pH close to 6 for a wide range of alkalinity.  133  Chapter 5. Results and Discussion  Figure 5.84: Change in Alkalinity in Columns 1-6  Time (day) Figure 5.85: Change in Alkalinity in Columns 7-12  Chapter 5. Results and Discussion  Figure 5.87: H R T , pH and Alkalinity of the Leachate at Steady State  134  135  Chapter 5. Results and Discussion  5.6.6  Specific Conductance  Figures 5.88 - 5.90 show the change in specific conductance in the columns during phases I, II and III. Specific conductance of the initial leachate ranged from 13 - 17 mS/cm. The values in all the columns decreased until the end of phase I. When HRTs were changed in phase II conductivity followed the dilution phenomena. Higher H R T columns (lower infiltration rates) had increased conductivity and lower HRT columns (higher flow rates) decreased in conductivity. In the Port Mann landfill study (Jasper et al., 1987), a decrease in specific conductance with high rainfall (due to dilution) was also observed. Pseudo mass of specific conductance released to the environment is discussed in the Section 5.7.  Phase I  0  100  Phase II  200  300  Phase III  400  500  Time (day) Figure 5.88: Change in Specific Conductance in Columns 1-6  600  136  Chapter 5. Results and Discussion  Phase I  o  >  o  ~o c o  o  100  200  300  400  600  500  Time (day) Figure 5.89: Change in Specific Conductance in Columns 7-12  100  200  300  400  500  Time (day)  Figure 5.90: Change in Specific Conductance in Columns 13-18  600  137  Chapter 5. Results and Discussion  5.6.7  Total Solids  Total solids ranged from 28,000 - 41,000 m g / L when the experiments were started (Figures 5.91 - 5.93). With time total solids decreased until the end of phase I. For new HRTs in phase II, total solids followed the same pattern as organic constituents. High H R T columns increased solids up to a period of close to one H R T and then decreased to stable concentrations. For the lowered HRTs solids decreased faster than it had been observed before lowering the H R T . When the HRTs were lowered in phase III, total solids decreased to very low values in a range 160 - 490 mg/L. Mass of total solids released to the environment is discussed in the Section 5.7. In the Port Mann landfill the total solids concentration stayed constant, irrespective of the seasonal variation in rainfall/infiltration (Jasper et al., 1987).  0  100  200  300  400  Time (day) Figure 5.91: Change in Total Solids in Columns 1-6  500  600  138  Chapter 5. Results and Discussion  Phase  100  300  200  500  400  600  Time (day) Figure 5.92: Change in Total Solids in Columns 7-12 P III  Phase I  40000 -p  100  200  300  400  Time (day) Figure 5.93: Change in Total Solids in Columns 13-18  500  139  Chapter 5. Results and Discussion  5.6.8  Nitrogen (NH - N, T K N ) 3  Change in T K N and NH  Z  - N with time are shown in Figures 5.94 - 5.99. T K N values  ranged from 250 - 1000 mg N / L at the beginning of the experiment and then decreased rapidly to a range of 10 - 60 mg N / L by the end of phase I. Ammonia Nitrogen was in the range 140 - 475 mg N / L and then decreased to a range 5 - 6 0 mg N / L by the end of phase I. T K N concentrations were approximately twice the N Hz — N concentrations throughout the study. This is very different from real landfills where most of the T K N is usually accounted for by NHz — N.  For example in Port Mann landfill (Jasper et  al., 1987) more than 90% of T K N was NHz — N. Addition of anaerobic digestor sludge could have added extra nitrogen that is not available for landfills. When the HRTs were increased, in columns 5, 6, 8, 9, 15 and 17, the T K N and NHz — N concentrations increased for a short period and then started to decrease. In others (columns 1, 3 and 4) there was a decrease in the rate of decrease in concentration. In columns 15 and 17 where HRTs were also increased, the leachate had an increase in NHz — N and T K N concentrations. After about 200 days, these also started to decrease. In columns 11, 12 and 14, where HRTs were decreased, the decrease in concentrations was faster. Analysis of leachate for ammonia nitrogen was not done for phase III. During this period some of the columns decreased in T K N very quickly. Some of them stayed steady for some time and then decreased. Mass of NHz — N and T K N released to the environment is discussed in the Section 5.7.  Chapter 5. Results and Discussion  0  100  140  200  300  400  Time (day) Figure 5.94: Change in T K N in Columns 1-6  Time (day) Figure 5.95: Change in T K N in Columns 7-12  500  141  Chapter 5. Results and Discussion 1200 -r  Phase I  Phase II  PIUY 160  1000 4-  800 4-  600  400  200 4-  100  200  300 Time (day)  400  500  Figure 5.96: Change in T K N in Columns 13-18  50  100  150  200 250 Time (day)  300  350  Figure 5.97: Change in Ammonia Nitrogen in Columns 1-6  400  142  Chapter 5. Results and Discussion  Time (day) Figure 5.98: Change in Ammonia Nitrogen in Columns 7-12  Time (day) Figure 5.99: Change in Ammonia Nitrogen in Columns 13-18  Chapter 5. Results and Discussion  5.6.9  143  Iron  The change in iron concentrations with time, during phases I and II, is given in Figures 5.100 - 5.102. They were different from column to column during phase I. For a short period of time concentrations decreased; then concentrations increased (except for columns 16 and 18) towards the end of phase I. During phase II, increasing iron concentrations were seen in columns where HRTs were increased. Columns 11, 12 and 14 where HRTs were decreased, showed decreased concentrations of iron relative to the controls. In other columns, iron concentrations remained steady throughout. These results showed that mobilization of iron continued throughout the experiments. Solubility of iron depends on pH and ORP. Methanogenic bacteria need very low redox potentials and cannot initiate growth at a potential higher than -330 m V (Zehnder, 1978). After this initiation, increases in O R P were shown to decrease methanogenic activity. Methane production rate is an indicator of the levels of O R P in the landfills. Higher CH4 production can be considered a sign of very low ORPs and lower CH4 production can be considered a sign of increasing ORP. But CH± production rate and O R P are not directly correlated. Continuous release of iron was observed, so was the release of carbon to the environment. Carbon released to the environment was dependent on CH  4  production rate. Therefore, iron concentrations were analyzed for possible correlations to CH4 production rate. Since solubility of iron depends on pH, iron concentrations were also analyzed for correlation to pH. Summary of these is given in Table 5.7. Regression plots are given in Appendices B and C. Five columns (1, 3, 4, 15 and 17) showed significant negative correlation to pH with correlation coefficients of 0.92, 0.87, 0.63, 0.94 and 0.86 respectively.  These columns  also showed significant positive correlation to CH4 production rate (0.81, 0.80, 0.49, 0.78 and 0.80 respectively). pH and iron solubility are negatively correlated. Methane  144  Chapter 5. Results and Discussion  production and pH are positively correlated. Columns 1, 3, 4, 15 and 17 which showed significant negative correlation with pH and positive correlation with CH4 production had two characteristics in common. Their HRTs were increased in phase II and CH4 productions were low.  When the H R T of low gas producing columns were increased,  their pH decreased. But their CH4 production rates kept increasing while pH stayed low during the period iron was analyzed. For these columns the effect of increasing H R T gave strong correlation to p H and CH4 production. This is a coincidence with the effect of the increase in H R T in low CH4 producing columns, i.e. kept decreasing their pH while CH4 production was increasing with time. Columns 5, 6, 8, and 9 also increased their HRTs. But the CH4 production rates were higher. They showed positive correlation for CH  4  production (0.81, 0.81 and 0.47 for columns 5, 6, and 8 respectively) except column 9 but showed no significant correlation for pH. From these data it is not possible to conclude which of the effects of pH or CH4 production is stronger. Columns 2, 7, 10, 13, 16 and 18 where H R T was not changed during this period only 16 significant correlation with respect to pH (correlation coefficients -0.46). Only columns 10, 16 and 18 showed significant correlation with CH4 production rates (-0.45, -0.47 and -0.64 respectively). HRTs of columns 11, 12 and 14 were decreased. Column 11 showed positive correlation to pH which is the opposite of the effect of pH on iron solubility. Column 11 and 12 showed negative correlation with CH  4  production (-0.51  and -0.71 respectively) which is the opposite of the expected effect from CH4 production. Correlations of iron to pH or CH4 production was linked to the changes in H R T and CH4 production stage of the column. These are summarized in Table 5.7 and can be grouped as follows; 1. Columns with low CH4 production and increased H R T in phase II showed strong negative correlation to pH and positive correlation to CH4 production  Chapter 5. Results and Discussion  145  2. Columns with low CH4 production and decreased H R T showed very small or no significant correlation to pH and negative correlation to CH4 production except one column 3. High CH4 production and increased H R T showed positive correlation to CH4 production and no significant correlation to pH 4. When the HRTs were not changed, correlations to pH was either very little (negative) or not significant and that for CH4 production was very small (negative) or none except one column showing a correlation of -0.64 to CH4 production These results show that the effects of pH and CH4 production rate on iron concentration is complicated in these landfill ecosystems and dependent on many other factors. Predictability of correlation of pH and CH4 production to iron concentrations in these columns in the long run is questionable due to the interrelated effects of pH, H R T and CH4 production. What is clear however is that iron continues to be released overtime and that leachate concentration is dependent on a set of factors not fully understood. The mass of iron released to the environment is discussed in Section 5.7.  146  Chapter 5. Results and Discussion  pH Column  #  ,  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  R -0.92 —  -0.87 -0.63 — — — — — —  +0.44 — — —  -0.94 -0.46 -0.86 —  Significant yes no yes yes no no no no no no yes no no no yes yes yes no  CH4 Production Rate Significant R yes +0.81 — no yes +0.80 yes +0.49 +0.81 yes +0.81 yes — no +0.47 yes — no -0.45 yes yes -0.51 -0.71 yes no — — no +0.78 yes yes -0.47 yes +0.80 yes -0.64  Table 5.7: Summary of Correlation Analysis of Iron Vs pH and CH4 Production Rate; yes - significant, no - not significant  Chapter 5. Results and Discussion  Figure  5.100: Change in Iron in Columns 1-6  147  Chapter 5. Results and Discussion  Figure 5.102: Change in Iron in Columns 13-18  148  Chapter  5.  Results and  5.6.10  Zinc  149  Discussion  T h e change i n zinc w i t h time is shown i n Figures 5.103 - 5.105. Concentrations of zinc in the columns at the beginning were in the range of 0 - 3.6 m g / L . Exceptions to these were columns 4, 6, 9 and 15 which had zinc concentrations of 6.3, 10.1, 8.4 and 21.2, respectively. W i t h i n two months, these had decreased to the range 0 - 3 . 6 m g / L . Other than this, there was no reduction i n concentrations w i t h time during phase I as opposed to other parameters measured. D a t a showed that continued mobilization of zinc to the environment. O R P and p H affects the solubility of metals. Therefore zinc concentrations were analyzed for correlation w i t h p H and CH  4  production rates (CH  production and  4  O R P are discussed i n Section 5.6.9). Correlation plots for p H and CH  4  production rates  are given in Appendices D and E . Results are summarized i n Table 5.8. Zinc concentrations showed significant correlation to p H i n columns 2, 3, 5, 7 and 18 (correlation coefficients -0.67, -0.78, -0.47, -0.43 and -0.93 respectively). Columns 10 and 13 showed significant positive correlation to p H (0.47 each). showed significant negative correlation to CH  4  Zinc concentrations  production i n thirteen columns. C o l u m n  3 showed positive correlation. These correlations were unpredictable.  Decreasing O R P  increases increases zinc solubility. W i t h increasing CH4 production p H increases and should decrease the solubility. H R T also affected the p H . T h i s complicates the solubility process. Analysis of the data showed this.  150  Chapter 5. Results and Discussion  pH Column  #  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  R —  -0.67 -0.78 —  -0.47 —  -0.43  — —  +0.47 — —  +0.47 — — —  —  -0.93  Significant no yes yes no yes no yes no no yes no no yes no no no no yes  CH4 Production Rate Significant R — no -0.73 yes +0.64 yes -0.49 yes -0.58 yes -0.41 yes -0.53 yes — no -0.63 yes -0.82 yes -0.45 yes -0.67 yes -0.68 yes -0.47 yes — no -0.44 yes —  -0.87  no yes  Table 5.8: Summary of Correlation Analysis of Zinc Vs pH and CH4 Production Rate; yes - significant, no - not significant  151  Chapter 5. Results and Discussion  0  50  100  150  200 250 Time (day)  300  Figure 5.103: Change in Zinc in Columns 1-6  350  400  152  Chapter 5. Results and Discussion  0  50  100  150  200 250 Time (day)  300  350  400  Figure 5.104: Change in Zinc in Columns 7-12  0  50  100  150  200 250 Time (day)  300  Figure 5.105: Change in Zinc in Columns 13-18  350  400  153  Chapter 5. Results and Discussion  5.6.11  Sodium  The change in sodium with time is shown in Figures 5.106 - 5.108. Sodium concentrations started within a range 250 - 500 mg/L and decreased with time, converging by the end of phase I. When the HRTs were changed in phase II, sodium concentrations in the columns with higher HRTs increased for some time and started to decrease. Columns where HRTs were decreased, decreases in concentrations were quicker than the columns with no change in H R T . The mass of sodium released to the environment is discussed in Section 5.7.  Time (day) Figure 5.106: Change in Sodium in Columns 1-6  154  Chapter 5. Results and Discussion  Time (day) Figure 5.107: Change in Sodium in Columns 7-12  Time (day) Figure 5.108: Change in Sodium in Columns 13-18  155  Chapter 5. Results and Discussion  5.6.12  Chloride  The change in chloride with time is shown in Figures 5.109 - 5.111. Chloride in leachate was only analyzed during the phase I. The chloride concentrations in the initial leachate were in the range 340 - 715 mg/L. Within 4 months, the concentrations decreased to a range of 20 - 60 mg/L, except for the column 16 which decreased in concentration to 80 m g / L and then showed an increase to 170 mg/L for the last sampling. Due to the low concentrations and the analytical difficulties (due to interferences) chloride was not measured after these 4 months.  700  T  0 -I 0  1  1  1  1  1  1  20  40  60 Time (day)  80  100  120  Figure 5.109: Change in Chloride in Columns 1-6  Chapter 5. Results and Discussion  Figure 5.110: Change in Chloride in Columns 7-12  Figure 5.111: Change in Chloride in Columns 13-18  156  Chapter 5. Results and Discussion  5.7  157  Pollutant Release to the Environment from the Lysimeters  Once the refuse is deposited in the landfill, physical, chemical and biological processes will take place. As a result gaseous, dissolved and suspended compounds in the form of leachate and gas are released. In this research it was observed that the releases are different from column to column depending on (but not correlating to all) many factors such as; infiltration rate (HRT), gas production rate (decomposition) etc.. The highest leachate concentrations of all the pollutants measured except inorganic carbon, zinc and iron for all the columns were observed at the beginning of the experiments. Mass releases of inorganic carbon was not analyzed since the initial concentrations of IC had analytical errors. The analytical difficulties for IC at the beginning of the experiments were discussed in Section 5.6.4. During phase I all the columns had the same HRT. By the end of this period, all contaminants, except inorganic carbon, iron and zinc, decreased to very low values. Therefore, most of the pollutants were leached to the environment during this period. Tables 5.9 - 5.11 gives the mass of the pollutants leached to the environment during phase I and phase II. Comparison of phase I and II shows that for all the constituents, 70 - 98% of the mass was leached during phase I (except for zinc and iron where 35 - 83% mass was leached). Comparison of concentrations of C O D , chloride and ammonia nitrogen for the volume of leachate produced was done with the prediction curves for these constituents by Reitzal et al. (1992) and are given in Figures 5.112 - 5.114. C O D concentrations are in agreement with the prediction curve except towards the end of the curve where the majority of the concentrations are little higher. After a leachate production of 3.5 liters (corresponds to 100 days) data points shift away from the exponential decay curve. C O D concentrations are dependent on biological activity in the landfills. Data on CH4 production and CH composition showed that biological activity increased with time. Leaching 4  158  Chapter 5. Results and Discussion  Column # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  HRT I 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35  (day) II 60 16 60 60 87 200 23 120 145 36 16 18 36 16 190 16 215 20  VFA I 1974 1898 1942 1809 2032 1818 1915 2094 1884 2293 2385 2578 2195 2740 1870 1687 1967 1922  (g) II 413 263 402 342 239 134 193 319 217 669 829 522 573 375 404 58 334 134  COD I 3568 3519 3691 3435 3927 3370 3524 3625 3498 3939 4309 4162 3798 4342 3716 2926 3590 2952  (g) II 912 704 1002 774 638 365 479 789 524 1641 1852 1126 1456 924 835 217 784 437  TOC I 855 850 829 817 934 790 810 820 799 990 1034 906 934 1033 864 670 891 738  (g) II 254 196 281 225 180 99 140 227 151 481 572 343 410 267 231 51 211 101  Alkalinity (g) I II 695 104 641 254 677 160 664 120 132 720 678 91 765 256 665 171 717 112 745 115 851 304 789 186 755 103 806 220 56 555 257 588 79 665 341 613  Table 5.9: Mass of V F A , C O D , T O C and Alkalinity Leached during Phases I and II  of soluble organic products with increasing biological activity would increase the C O D concentration. Chloride concentrations are not affected by the biological activity. They did not show much scatter as in C O D and were well below the chloride prediction curve. Ammonia nitrogen concentrations showed good agreement with the ammonia nitrogen prediction curve. In summary, releases of chloride and sodium were not dependent on the biological activity.  Release of organics to the environment is through gas and leachate.  These  were dependent on the biological activity and continuous release occurred throughout the experiment. Release of zinc and iron are controlled by the chemical characteristics of the refuse mass which is also dependent on the biological activity. Continuous release  159  Chapter 5. Results and Discussion  Column # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  HRT (day) II I 35 60 16 35 35 60 35 60 87 35 35 200 23 35 35 120 35 145 36 35 16 35 35 18 35 36 16 35 35 190 16 35 35 215 35 20  Conductivity ((mS/cm)Xml) II I 323 1303 465 1337 382 1343 303 1345 1418 250 173 1330 438 1364 301 1340 1336 228 1429 541 782 1546 492 1436 417 1429 541 1498 237 1245 432 1175 235 1326 536 1234  Total Solids (g) I II 508 2530 2389 645 2473 618 2572 480 442 2760 2436 286 2515 559 2482 571 2725 379 2882 757 3027 1187 2856 694 2810 632 816 3000 2255 383 2247 547 2574 409 2319 704  TKN (g) I 47.9 65.4 74.0 43.2 65.3 44.9 53.6 46.0 28.3 53.8 53.2 43.5 37.0 56.2 77.4 23.7 42.7 28.1  II 3.2 5.6 5.0 4.8 3.6 2.1 5.4 4.3 2.0 6.4 7.7 5.0 4.9 5.9 7.1 4.2 4.3 3.7  -  (g) I 25.8 36.8 37.6 28.0 33.4 29.1 33.4 34.4 19.4 21.9 31.7 25.6 22.3 31.8 41.1 16.3 25.2 19.1  N  II 1.3 4.3 2.4 3.0 2.4 1.2 2.5 2.6 0.4 1.3 2.8 1.6 0.8 2.0 4.6 0.5 2.2 1.8  Table 5.10: Mass of Conductivity, Total Solids, T K N and NHz - N Leached during Phases I and II  of zinc and iron also was observed. Presence of sulfate in the landfill will precipitate metals as sulfide. decrease metal levels in leachate.  This will help  But in this work continuous release of zinc and iron  was observed indicating absence or presence in very small quantities of sulfates. This is further strengthened by the levels of methanogenesis of the columns. This research involved infiltration rates higher than most of the lysimeter studies published. Therefore one would suspect higher releases to the environment. Data for chloride showed that they are lower than the data used in the Reitzal et al. (1992). Release of organics to the environment depends on the break down of the solid organic  160  Chapter 5. Results and Discussion  Column # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  HRT I 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35  (day) II 60 16 60 60 87 200 23 120 145 36 16 18 36 16 190 16 215 20  Iron I 9.7 13.6 15.8 18.8 14.1 15.1 17.9 13.7 17.5 14.6 18.5 24.0 21.7 12.7 11.3 20.6 9.7 11.0  (g) II 12.5 18.7 25.0 19.0 11.0 10.1 23.6 8.5 8.8 17.4 34.8 40.3 29.2 14.0 10.7 20.8 7.0 8.5  Zinc ' g) I II 118 120 84 42 67 112 555 218 92 23 475 61 37 19 165 62 695 146 604 472 136 212 311 542 361 363 76 67 1027 337 82 16 294 112 406 90 m  Sodium (g) I II 18.1 0.5 26.5 2.3 23.5 0.8 0.6 26.5 27.2 1.0 24.9 0.4 24.4 0.8 22.3 0.6 21.4 0.4 18.5 0.8 25.8 1.3 0.7 25.2 24.2 0.8 26.2 1.1 27.6 0.8 15.7 0.8 18.7 0.6 1.7 20.4  Table 5.11: Mass of Iron, Zinc and Sodium Leached during Phases I and II  materials. This was shown by the higher concentrations than the prediction curve with time (towards the end of the graph) when CH production was increased (Figure 5.112). 4  Organic carbon release to the environment is further discussed in the Section 5.9.  161  Chapter 5. Results and Discussion  70000  T  60000 Y=40000 exp(-0.49X)  50000 O) 40000 £ 8 30000 O 20000 10000 4-  2  .  4  6  8  Volume of Leachate per kg of Refuse (L) 5000 4500 4000  J x  >°$00  3500 |  Y=40000 exp(-0.49X)  *  ^  •  3000 \ % •<>  w 2500 ;oO  •  s  O 2000 -j- O $ o v  1500 £ 1  0  0  0  500  $  J*** *  ' *  I  _4 13  18  23  28  I t  0|  33  $o_  -«438  Volume of Leachate per kg of Refuse (L)  Figure 5.112: Comparison of C O D with the C O D Prediction Curve by Reitzal et al., 1992  Chapter 5. Results and Discussion  1800  162  T  Volume of Leachate per kg of Refuse (L) Figure 5.113: Comparison of Chloride with the Chloride Prediction Curve by Reitzal et al., 1992  700 -r  Volume of Leachate per kg of Refuse (L) Figure 5.114: Comparison of NHz — N with the NHz — N Prediction Curve by Reitzal et a l , 1992  163  Chapter 5. Results and Discussion  5.8  Micro-environments  Enhancement of CH  4  production with increase in moisture content and moisture move-  ment can be due to many reasons.  Transportation and distribution of nutrients and  carbon sources and dilution of inhibitors are the possible primary factors. During phase I of the experiments all the lysimeters were given 1150 ml/day infiltration. Leachate characteristics in all the lysimeters were similar with respect to organic carbon; however, the gas productions were different. Some factors that would have lead to the differences in initiation of gas production were discussed in Section 5.3. After the gas production was initiated, this itself is speculated to be a factor in increasing methanogenesis.  During  the first 60 days of the experiments, the pH values in all the lysimeters were 5.5 ± 0.2. Lysimeters with high gas production (VFA consumed) showed increasing pH. Higher pH further helps methanogenesis.  Lysimeters with low gas production eventhough there is  limited V F A consumption had a decreasing pH. This is not favorable for methanogenesis. During phase I all the experimental conditions were identical. Gas production rates and composition of gas were different but leachate constituent concentrations were identical with respect to organic carbon. This leads to the speculation that microenvironments are responsible for the behavior of the lysimeters and the constituent concentrations in leachate are not the concentrations in the microenvironments. For example, V F A concentrations in a microenvironment is the difference between V F A produced (by solid hydrolysis and fermentation of sugar) and V F A consumed for gas production (assuming there is no water flowing through the refuse). Hydrolysis and fermentation are dependent on the removal of V F A by gas production. Barlaz et al. (1989) observed little solid hydrolysis during this period of their study and suggested that feedback inhibition due to accumulated acids. Therefore the majority of the VFAs during the first 60 days are from fermentation of sugars. V F A concentration in the microenvironment cannot be higher  Chapter 5. Results and Discussion  164  than the concentration that is inhibitive to hydrolysis and fermentation. Consequently, up to a certain rate of gas production, VFAs are the same in microenvironments when the rate of V F A production (hydrolysis and fermentation) is less than its maximum due to the inhibition. This was seen during first 60 days from leachate V F A concentrations. When the VFAs in microenvironments are similar, the rate of transfer of VFAs to passing water will be the same if the flow rate of water is the same and as such leachate V F A concentrations were nearly identical during the first 60 days. But, with time, gas production rates of some columns increased rapidly. When this happens, VFAs are removed from the microenvironments faster than they are produced. This will decrease the V F A concentrations in the microenvironments. This is reflected by the reduced leachate VFAs in the high gas producing columns. Towards the end of the experiments, leachate V F A concentrations were not detectable in some columns while having high gas productions.  5.9  Carbon Released to the Environment  Landfills receive degradable organics from different sources. When the refuse is deposited in the landfills physical, chemical and biological processes occur. Biological processes are responsible for stabilization of the landfill with respect to organics. Hydrolysis of solid organic matter and complex dissolved organic matter to VFAs and alcohols is required for the biostabilization of this organic carbon. Hydrolysis of the organics is the most important process in the landfill stabilization. This is discussed in Sections 5.10 and 5.11. After hydrolysis, these products can be removed from the landfill environment either as gas or in leachate. This will depend on the extent of methanogenesis in the landfill and the availability of infiltration. Also, these two are very much interdependent; methanogenesis is affected by infiltration. The mass of organics removed due to infiltration is dependent on the extent of methanogenesis. Organic carbon in the landfills will be either converted  165  Chapter 5. Results and Discussion  to gas or leached with infiltrating water. Initially, most of the organic carbon was leached with infiltrating water while a small portion was converted to CH4 and C0% With time, organic carbon converted to CH4 and CO2 increased, consequently decreasing organic carbon mass in the leachate. From the data obtained during phases I, II and III carbon released to the environment as gas and leachate were estimated. The methods for calculating carbon in leachate and gas are given in Sections 5.9.1 and 5.9.2 respectively with sample calculations. In calculating carbon released in leachate VFAs were used instead of T O C since V F A represents the biodegradable portion of T O C .  5.9.1  Carbon in Leachate  Organic carbon in leachate was estimated using V F A concentrations. VFAs were analyzed in terms of acetic acid, propionic acid, butyric acid and valeric acid. Amounts of carbon in each were calculated as follows and added to get the total carbon (as carbon) in leachate. Carbon in acetic acid  = (Acetic acid cone.)X(24/60,000) g / L  Carbon in propionic acid  = (Propionic acid cone.)X(36/74,000) g / L  Carbon in butyric acid  = (Butyric acid conc.)X (48/88,000) g / L  Carbon in valeric acid  = (Valeric acid conc.)X (60/102,000) g / L  Concentration of carbon in leachate = Total of above 4 items  Sample calculation: Column 5 for the 126 th day; Acetic acid concentration  = 1590 mg acetic acid/L  Chapter 5. Results and Discussion  Carbon in acetic acid  (Acetic acid conc.)X(24/60,000) g / L 0.64 g/L  Propionic acid concentration  440 mg propionic acid/L  Carbon in propionic acid  (Propionic acid conc.)X(36/74,000)g/L 0.21 g/L  Butyric acid concentration  803 mg butyric acid/L  Carbon in butyric acid  (Butyric acid conc.)X (48/88,000) g / L 0.44 g/L  Valeric acid concentration  540 mg valeric acid/L  Carbon in valeric acid  (Valeric acid conc.)X (60/102,000) g / L 0.32 g/L Total of above 4 items  Concentration of carbon in leachate  0.64 + 0.21 + 0.44 + 0.32 g / L 1.61 g/L 1.61 g / L X flowrate  Total carbon leached  1.61 g / L X 1.15 L/day 1.85 g/day  5.9.2  C a r b o n in Gas  Sample calculation: For column 5 for the 126 th day;  PV  = nRT  Where; P  = 1 Atmospheric Pressure  167  Chapter 5. Results and Discussion  V  = Volume of gas in Liters  n  = Number of moles in the sample  T  = Temperature of Gas in Kelvin degrees = 20 ° C = 20 + 273 °K  R  = 0.082 L*atm/mol*K  n  = V/(0.082 X 293) = V/24.026  Concentration of C0  = 46.1%  Concentration of CH4  = 46. 9%  Rate of gas production  = 5.01 L/day  2  Carbon in gas as C0  (g/day) = 12 X moles of  2  = 12 X (C0  2  C0  2  volume/24.026)  = (12/24.026) X C0  2  cone. X Rate of gas production  = (12/24.026) X 0.461 X 5.01 = 1.15 g/day Carbon in gas as CH  A  (g/day) = (12/24.026) X 0.469 X 5.01 = 1.17 g/day  Total carbon in gas  = 1.15 -f- 1.17 g/day = 2.32 g/day  Cumulative carbon released in the leachate ranged from 800 - 1500 grams. Lower values were related to high gas production columns and high amounts were related to low gas production columns. Cumulative carbon released in the gas phase ranged from 540 - 2270 grams by the end of phase IV. During the early stages, leachate carried a higher percentage of organic carbon from the landfill. With time, carbon released in the  168  Chapter 5. Results and Discussion  gas phase showed an increasing trend. For some columns, the rate of carbon released in the gas reached a peak and then started to decrease during the study period. Others had an increasing trend until the end of experiments. Leachate carbon concentrations were very small towards the end. Cumulative carbon released in gas or leachate was dependent on the gas production of each column. Figures 5.115 - 5.132 illustrates the rates of carbon released and cumulative carbon released as gas and leachate in the columns. Column 10 had the lowest gas production at the beginning and took a long time to get the methanogenesis established. As a result, VFAs were leached unused by the methanogens. Therefore, carbon released in the leachate was high (1375 g of which 1000 g was leached in the first quarter of the experiment).  This was the case with all the  low gas producing columns. Column 1 and 2 established their gas production from the beginning and kept increasing. The initial VFAs were used by the methanogens and still a portion of these products were leached in the leachate.  Column 1 leached a total of  1147 g with 900 g in the first quarter. Column 2 leached a total of 1028 g with 850 g in the first quarter. However, with time, most of the VFAs were consumed by the bacteria, thus increasing the carbon released in the gas phase and decreasing the carbon in leachate. All the high gas producing columns behaved in the same pattern. As discussed earlier, organic carbon released to the environment is dependent on many factors. First of all the availability of soluble organic carbon. When the refuse is placed in landfills, readily biodegradable organic compounds will be hydrolyzed and fermented by fermenting bacteria to volatile fatty acids and alcohols. Therefore, during the early stages of the experiment these can be mobilized and result in high carbon concentrations in leachate.  But after this source is depleted, the availability of organics depends on  the degradation of solid organics; cellulose, hemicellulose etc.. Therefore, at this stage, organic carbon released to the environment depends on the extent of biological activity within the landfill. This is shown in the Figure 5.133. During phase I, the total carbon  169  Chapter 5. Results and Discussion  released to the environment was very similar in all the columns. During phase II, the total carbon released was dependent on the CH  4  production Figures 5.133). Summary  of carbon releases and total gas produced is given in Table 5.12.  Column #  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  Cumulative C released in gas (g) 1275 2189 658 1224 1991 1787 2150 2269 1123 733 885 631 588 645 1094 1833 540 1054  Cumulative C released in leachate (g) 1148 1029 1128 1001 1099 916 1005 1144 976 1375 1496 1438 1301 1480 1128 815 1113 984  Total C released in gas and leachate (g) 2423 3218 1786 2225 3091 2704 3155 3413 2099 2108 2381 2069 1888 2125 2222 2648 1653 2038  Cumulative methane produced (L) 1451 2566 736 1447 2197 2028 2557 2528 1289 865 1084 838 710 832 1260 2203 539 1326  Table 5.12: Summary of Carbon Releases from the Landfill  Figure 5.133 shows high gas producing columns released more carbon than the low gas producing columns. Carbon released through leachate had tailed off in all the columns. The trend for high gas producing columns shows that their release of carbon to the environment is decreasing (Figures 5.116, 5.119, 5.120, 5.121, 5.122, 5.123, 5.130 and 5.132). In these columns, the gas production decreased and have released carbon to the environment in the range of 2700 - 3400 grams, except columns 9, 16 and 18. Columns  Chapter 5. Results and  170  Discussion  9, 16 and 18 released 2100, 2650 and 2040 grams respectively. When the data collection was started, column 16 had 40% CH  4  concentration and the highest gas production rate.  A reasonable amount of initial carbon released in the gas phase was not accounted for. Column 18 and 16 lost CO2 into the leachate which brought the CH  4  concentration of up  to about 90%. Carbon in the CO2 lost to leachate was also not accounted for. Therefore, it would be fair to consider that columns 16 and 18 also had the carbon released to the environment in the above high range. Column 9 slowed down in gas production after about 200 days probably due to the increase in HRT. Decrease in CH  production was  observed in both columns 8 and 9. But column 8 started to increase CH  production after  4  4  about a month of changing H R T . Column 9 had all the other characteristics associated with high gas producing columns. This column could be an exception. Low gas producing columns released carbon in the range 1650 - 2400 grams. These columns also showed a decreasing trend in gas production. Therefore, most likely these columns would release 50% (or even more) less carbon than the high gas producing columns. All the eighteen columns in this study received the same amount of organic material at the beginning. Therefore, they all had the potential for releasing similar amounts of carbon to the environment.  Carbon release was dependent on the  CH  4  production stage of the columns, indicating the importance of biological activity in stabilizing a landfill. What could be happening in these low gas producing columns is an interesting point of conjecture. Barlaz et al. 's (1989) results showed that during the first two stages of decomposition soluble sugars are fermented and released increasing VFAs in the leachate. This was not seen in this study, since, when the sampling started all the columns had passed this stage. Highest VFAs and a p H of 5 . 5 ± 0 . 2 were measured at the beginning and VFAs had a decreasing trend. This and the increasing CH  4  production showed establishing  methanogens which were utilizing VFAs from soluble sugar fermentation according to  171  Chapter 5. Results and Discussion  Barlaz et al. (1989). Very little solid hydrolysis occurred in their study during the first three phases. With time, carbon released in the leachate decreased due to the decrease in available soluble organics. This could be attributed to either; the VFAs are converted to gas or limiting solids hydrolysis or both. Increasing conversion to gas was seen by the increase in carbon in the gas phase. Some of the columns started to decrease their CH  4  production rate which is charac-  teristic of decelerated methane phase (Barlaz et al., 1989). According to them polymer hydrolysis limited the refuse methanogenesis. Continuous decrease in methane production was suggested to be due to concurrent decrease in polymer hydrolysis and is explained as the preferential use of cellulose and hemicellulose which are less heavily lignified. Once the cellulose and hemicellulose are degraded during this period the remaining refuse becomes high in lignin content.  Khan (1977) found in his study the presence of higher  proportion of lignin in cellulose products adversely affected the ability to degrade cellulose by the mixed culture used. In summary Carbon released to the environment during the initial stages will depend on the availability of soluble organic carbon and will be released mainly as leachate. When this source is depleted the hydrolysis of the solid organic carbon will control the release of the carbon to the environment. Hydrolysis of the solids will be controlled by the use of these products by methanogens or it being carried away by infiltrating water; In addition hydrolysis is mediated by extracellular enzymes produced by fermenting bacteria (Jones et al., 1983). These show the interaction of the biological processes in the landfill stabilization process which in turn affects the extent to which the landfill organics are degraded.  172  Chapter 5. Results and Discussion  Time (day)  1400  T  700 Time (day) Figure 5.115: Carbon Released to the Environment from Column 1  173  Chapter 5. Results and Discussion  200  100  300  400  600  500  Time (day)  2500 -r  ^2000  o C in Gas • C in Leachate  O)  V.  '  C  o •§1500 O Q) >  ^^•••••••••grjtarjnrj  1000 .•  100  • rxrunnn  n D  200  300  400  500  600  Time (day) Figure 5.116: Carbon Released to the Environment from Column 2  700  4  174  Results and Discussion  Chapter 5  T  • C in Gas •C in Leachate  100  200  300  500  400  600  Time (day)  1200  o C in Gas  1000 +  • • • • • • • •  • C in Leachate  100  200  300  400  n ^  0  0  500  0  600  Time (day) Figure 5.117: Carbon Released to the Environment from Column 3  700  175  Chapter 5. Results and Discussion  100  200  300  500  400  600  Time (day)  1400 -r  o C in Gas 1200  • C in Leachate  o  ^1000 o .Q O 800 O  DnoaDD  °°°°  DDDDD  $  n  CD  £ 600 o § 400 O 200  0  100  200  300  400  500  600  Time (day) Figure 5.118: Carbon Released to the Environment from Column 4  700  176  Chapter 5. Results and Discussion  0  100  200  300  400  500  600  Time (day)  0  100  200  300  400  500  600  Time (day) Figure 5.119: Carbon Released to the Environment from Column 5  700  177  Chapter 5. Results and Discussion  Time (day)  1800 -r 1600 31400 +  o C in Gas §1200 • C in Leachate .Q °1000 + CD  > 800 -H-  D 3 600 + £ O 400  Q  °  00°  200 4-  D  0 0  100  200  300  +  400  500  600  Time (day) Figure 5.120: Carbon Released to the Environment from Column 6  700  178  Chapter 5. Results and Discussion  0  100  200  300 400 Time (day)  500  600  o C in Gas • C in Leachate  c o •S 1500 + O 351000 f e 3  500  0  100  200  300  400  —I— 500  600  Time (day) Figure 5.121: Carbon Released to the Environment from Column 7  700  179  Chapter 5. Results and Discussion  Time (day) Figure 5.122: Carbon Released to the Environment from Column 8  180  Chapter 5. Results and Discussion  1200  T  700 Time (day) Figure 5.123: Carbon Released to the Environment from Column 9  181  Chapter 5. Results and Discussion  Time (day)  0  100  200  300  400  500  600  Time (day) Figure 5.124: Carbon Released to the Environment from Column 10  700  182  Chapter 5. Results and Discussion  0  1600  100  200  300 400 Time (day)  500  600  T  700 Time (day) Figure 5.125: Carbon Released to the Environment from Column 11  183  Chapter 5. Results and Discussion  Time (day)  1600  o C in Gas  1400  anna  • C in Leachate  0 0  C M 200  0  100  200  300  400  500  600  Time (day) Figure 5.126: Carbon Released to the Environment from Column 12  700  Chapter 5. Results and Discussion  184  Time (day)  1400 -r  700 Time (day) Figure 5.127: Carbon Released to the Environment from Column 13  185  Chapter 5. Results and Discussion  Time (day)  Figure 5.128: Carbon Released to the Environment from Column 14  186  Chapter 5. Results and Discussion  Time (day)  Figure 5.129: Carbon Released to the Environment from Column 15  187  Chapter 5. Results and Discussion  Time (day)  2000  T  700 Time (day) Figure 5.130: Carbon Released to the Environment from Column 16  188  Chapter 5. Results and Discussion  4  T  C in Gas C in Leachate  1200  300 400 Time (day)  200  100  500  600  o C in Gas  1000 + • C in Leachate  nnnnoDD  • • • • • • •  100  200  D  D  D  1  3  0  0  D  300  400  500  600  Time (day) Figure 5.131: Carbon Released to the Environment from Column 17  700  Chapter 5. Results and Discussion  189  Chapter 5. Results and Discussion  190  o Total C Released during P II x Total C Released - end of P I A Total C Released - end P I  3500  x XX  3000 + 2500 * XX*  2000  O o  1500  0  A  1000  o ~o o  500  50  +  +  +  100 150 200 250 Cumulative CH-4 Production (L)  300  350  Figure 5.133: Carbon Released to the Environment in Relation to the CH Production 4  191  Chapter 5. Results and Discussion  5.10  General Overview  H R T affects landfill leachate and gas characteristics.  The effects of H R T on landfill  gas composition and leachate p H and organic constituent concentrations were the most noticeable and important with regard to stabilization of landfills. This indicates that H R T affects methanogenesis. Quantitative analysis of the effects was not possible due to the time trends in the data but some observations were possible. These are summarized in Tables 5.13 to 5.15 for the period of phase II. When the HRTs were reduced below 60 days, exponential increase in CH4 concentration was observed. With the decrease in CO2 concentration to 8% in gas and the increase in IC in leachate, it is evident that a major portion of the C0  2  stayed in infil-  trating water. It is suggested that the increase in CH4 concentration is also due to the enhancement of methanogenesis, as a result of decreased C0  2  partial pressure and other  effects such as increasing pH of low gas producing columns and dilution of inhibitive concentrations of VFAs. This is supported by the fact that there was no decreased gas production (Figures 5.39 - 5.44), which is expected when a noticeable portion of produced CO2  w  a  s  dissolved in the infiltrating water. Also, from the Table 5.6, it can be seen that  CH4 concentration has increased after the period of three months with low C0  2  partial  pressure. When the columns had identical decomposition history, lower HRTs showed an increase in CH4 production by the end of the phase II. In addition to these, there are other effects that will come into play due to low H R T (high infiltration); lowering  C0  2  partial pressure, increasing pHs of the low gas producing columns, moisture distribution which is essential for methanogenesis, transport of nutrients and organic carbon in the refuse and dilution of inhibitors. Wreford (1995) analyzed the factors affecting landfill gas composition and production and leachate characteristics at the Vancouver landfill site at Burns Bog. Her results  192  Chapter 5. Results and Discussion  indicated that precipitation had the most prominent effect.  Cumulative precipitation  from 14 days prior to sampling showed the strongest relationship to CH4 production at the individual gas wells. Her observations support the findings of this research. Port Mann landfill and other landfills discussed in Chapter 2 show high organic concentrations in leachate following high rainfall period. This was suspected to be due to the failure of methanogenesis as a result of decrease in HRT. An increase in infiltration rate decreases the HRT, and it does affect the leachate and gas characteristics. But, in this research decreases in H R T due to increase in infiltration rate enhanced the methanogenesis. Field studies done by Wreford (1995) showed an increase in CH4 concentration and CH4 production in Burns Bog landfill, Vancouver during the high rainfall periods. Therefore the increase in organic loadings during the periods of high rainfall in Port Mann landfill is unlikely to be due to the failure of methanogenesis as a result of low H R T with high infiltration. In the Port Mann case there was no gas collection system, so parallel measurements were not made. The research data from Rovers and Farquhar (1973) showed a decrease in CH4 concentration from 17% to 6% with an increase in C O D , B O D and volatile dissolved solids and a decrease in alkalinity and pH in the resulting leachate. These observations were explained as the failure of methanogenesis during periods of rapid infiltration. The excessive infiltration was due to snow melting during spring. They felt since there was only 2 ° C drop in temperature, the failure could not be due to a decrease in temperature. Reduction of pH was thought to be a result of failure in methanogenesis rather than a cause. The cause of failure was explained as due to the increase in oxidation-reduction potential (ORP) which would have occurred during the melted ice and snow infiltration. However, O R P was not measured in their experiments. Their results showed that the CH4 concentration dropped to 6%. Gas samples were taken from the bottom of the refuse column. When the methanogenesis failed in their  Chapter 5. Results and Discussion  193  work (in cell C\) 200 liters of infiltration (calculated from Figure 1 in Rovers and Farquhar, 1973) occurred over a period of approximately 20 days. A n average infiltration rate of 4 mm/day took place in this cell over a period of 20 days. Moisture absorbed was 740 liters. And the moisture content at placement was 1505 liters (62% X 2428 L). According to Equation 5.2, these will give an H R T of 224 days (S = 2245 liters, Q = 10 L/day). This is close to the highest H R T (200 days) tested in this research (phase 11 columns 6, 15 and 17). Infiltration rates of 3.5 mm and 5.0 mm were used to achieve HRTs of 120 and 200 days respectively. When the HRTs of the columns in this work shifted to 120 and 200 days from 35 days, methanogenesis slowed down compared to H R T of 35 (comparison of columns 7 and 8 and 2, 5 and 6 in Section 5.4). But in Rovers and Farquhar (1973) infiltration rate increased from 0 mm/day to 4 mm/day. This should favor methanogenesis. Therefore the failure of methanogenesis would not appear to be just due to reduction in H R T with rapid infiltration. It could be due to some other factor introduced with the cold water infiltration.  Also it was observed in this research that the effects of H R T was  dependent on the stage of the decomposition of the refuse mass. For example column 6 had very high gas production and its pH did not decrease when the H R T was increased as did its triplicate columns 15 and 17. The effect seen in Rovers and Farquhar's (1973) work could be due to the unestablished methanogenic population indicated by low CH<\ concentration. Leckie's study consisted of 5 landfill cells. Two of them had continuous water inflow and recirculation. These had higher methanogenesis than the other three. During the second winter high infiltration occurred through four of the columns.  Columns with  established methanogenesis kept increasing methane concentration. The control did not establish methanogenesis. When water infiltrated due to the cracks in the cover, organic carbon in leachate increased. The other two cells had some methane in the gas (5 - 10%).  194  Chapter 5. Results and Discussion  After the increased water inflow, leachate organic carbon increased in both columns. Effect on CH4 concentration was different. One cell kept increasing CH4 concentration while the other decreased. The behavior of the cell with decreased CH4 concentration is similar to what happened in Rovers and Farquhar's (1973) work. Therefore it could be that unestablished methanogenesis was disturbed by the increased infiltration. Burns Bog landfill had established methanogenesis when the study started (Wreford, 1995). Methane concentration and methane production increased with rainfall. The same trend of increasing organic constituents was also observed at the Richmond landfill during high water input (application of dredge from the Fraser river) (Soper and McAlpine, 1977). At neither the Port Mann landfill (Jasper et al., 1987) nor Richmond landfill (Soper and McAlpine, 1977) were gas characteristics measured and hence one is unable to analyze the effect of H R T on overall methanogenesis. pH of initial leachate were between 5.2 and 5.5. With time increasing pH for high CH4 producing columns and decreasing pH for the other were observed. High C i 7 producing 4  columns increased their pH irrespective of the change in H R T during phase II. When H R T was increased in low CH4 producing columns pH decreased until CH4 production was established, and then started to increase. Decreasing H R T of low CH4 producing columns increased the pH due to the dilution of VFAs. When H R T was decreased in the high gas producing columns with pH higher than 5.8, a slight decrease in pH was observed. With high infiltration through landfills, significant amount of CO2 dissolves in water. According to water chemistry, the pH should decrease. But in this work it was seen that columns that had higher VFAs, have increases in pH. This helps methanogenesis. Columns that had low V F A , high gas production and higher pH, decreased their pH and stabilized around a pH of 5.7.  No detrimental effect on methanogenesis was observed  due to decrease in pH. From Figure 5.87, it can be seen that lower HRTs due to higher infiltration, gives a pH close to 6 for a wide range of alkalinities. This is also a favorable  195  Chapter 5. Results and Discussion  effect of low H R T on methanogenesis. Correlation analysis for zinc and iron for pH and methane production rates showed different correlations from column to column. Correlation of iron concentrations to pH and CH4 production was dependent on the changes in H R T and CH4 production stage of the columns. These correlations could be due to the coincidence of effects of H R T on iron concentrations. Therefore predictability of correlations in a different situation is questionable. Correlation of zinc concentrations to pH and CH  4  production was unpredictable.  Increasing methane production increases pH which should decrease the solubility of metals. If increasing pH is always due to increasing methane production, combined effect should be predictable or the data should show the combined effect. But data analysis showed very different unpredictable correlations showing the complicated nature of the solubility of metals in the landfill ecosystem.  196  Chapter 5. Results and Discussion  After 163 days of HRT=35 days Cumulative CH pH production (L) 5.74 635.9 5.39 197.1. 5.52 172.7 4.99 30.1 4.87 27.2 4  HRT Changed to (day) <—> <—• *—•  <—•  194.8 191.2 166.5 175.8 95.1 33.6  5.46 5.56 5.33 5.58 5.14 5.14  |120 T120 |120 T200 |200 T200  94.5 76.3  5.39 5.4  |60 |60  66.6  5.46  T60  66.0  5.33  118  38.6 31.5  5.26 5.33  118 118  Effect on pH  increased increased increased decreased decreased until day 308* increased increased increased increased decreased decreased decreased decreased until day 329* decreased until day 443* decreased until day 308* increased decreased until day 266*  Effect on Iron Correlations either very little significant correlation to p H / C i / 4 production rate or were not significant no significant correlation to pH and positive correlation to CH4 production rate strong negative correlation to pH and strong positive correlation to CH4 production rate  very small or not significant correlation to pH and -ve correlation to CH4 production rate except one column  Table 5.13: Effect of H R T on pH and Iron Concentrations;<—>=not changed, | = increased, J.=decreased, *=then started to increase pH  197  Chapter 5. Results and Discussion  After 163 days of HRT=35 days Cumulative CH4 pH production (L) 5.74 635.9 5.39 197.1 5.52 172.7 4.99 30.1 4.87 27.2 5.46 194.8 5.56 191.2 5.33 166.5 5.58 175.8 5.14 95.1 5.14 33.6 5.39 94.5 5.4 76.3 5.46 66.6 5.33 66.0 5.26 38.6 5.33 31.5  HRT Changed to (day)  Effect on V F A , COD, T O C , TS, Na and specific conductance  <—> <—• <—>  kept decreasing  <—• <—•  T120 T120 T120 T200 T200 |200 T60 T60 T60 118 118 118  increased for some time and then decreased  kept decreasing  Alkalinity End of Phase II (mg/L as CaCOz) 340 495 460 135 205 770 895 740 1060 510 695 150 370 365 x  200 165 160  summary  high CH4 prod. and high H R T maintained high values; high CH4 prod. and low H R T maintained a medium range; low CH4 production low HRT had very low values; low CH4 production and high H R T had medium values  Table 5.14: Effect of H R T on V F A , C O D , T O C , TS, Na and Specific Conductance;^—>=not changed, T= increased, J.=decreased, = had very low values from the begining x  198  Chapter 5. Results and Discussion  After 163 days of HRT=35 day Cumulative CH4 production (L) 635.9 197.1 172.7 30.1 27.2 194.8 191.2 166.5 175.8 95.1 33.6 94.5 76.3 66.6 66.0 38.6 31.5  pH  HRT Changed to (day)  Effect on T K N and  Effect on Zinc Concentrations  NH - N Z  5.74 5.39 5.52 4.99 4.87 5.46 5.56 5.33 5.58 5.14 5.14 5.39 5.4 5.46 5.33 5.26 5.33  *—•  <  •  <  •  *  •  kept decreasing  continuous release was observed  *—•  T120 T120 T120 T200 T200 |200  kept decreasing increased for some time and then decreased  T60 T60 T60  decreased in a reduced rate than before  118 118 118  kept decreasing  Table 5.15: Effect of H R T on T K N , NH -N j=decreased 3  showed unpredictable correlations to pH and methane production rate  and Zinc;<—>=not changed, T= increased,  199  Chapter 5. Results and Discussion  5.11  Potential Applications of Findings  As discussed in Section 2.5.8, researchers still debate the optimum moisture content for methanogenesis in landfills. From a microbial stand point, moisture content in the refuse is an important factor in landfill stabilization. It facilitates the hydrolysis process. Removal of VFAs produced by enhanced gas production will reduce the hydrogen partial pressure and reduce feedback inhibition of hydrolysis. This will also give higher CH  A  production which will make recovery of gas for energy more feasible. If the CH recovery 4  is not intended, removal of VFAs by means of moisture movement (infiltration) will also enhance landfill stabilization. But an active population of methanogenic bacteria will keep the hydrogen partial pressure low enough for acetogenic bacteria, which convert other VFAs to acetic acid to be used by acedogenic bacteria.  Infiltration also helps  methanogenesis by means of providing the solution and transport of CC>2- Low partial pressures enhance methanogenesis.  C0  2  This work showed that moisture availability  higher than field capacity will help methanogenesis and stabilize the landfill faster. The problem of souring due to accumulation of acids has been observed in many research projects during the early stages of decomposition (for example, Barlaz et al. (1989), Fungaroli and Steiner, (1971)). Barlaz et al. (1990) discussed the importance of research to solve the problem of souring. Separation of food waste from the waste stream and composting them prior to landfilling was identified as a solution.  This is a good  method for future landfills. But for the existing landfills, lowering the H R T by increasing the infiltration can be used to solve the problem of souring as it will increase the pH and decrease the VFAs (column 11, 12 and 14 in phase II and columns 17, 13 and 1 in phase III). Most modern landfills are designed to prevent rainfall and ground water from entering the refuse mass. This creates a moisture deficient environment within the landfill  200  Chapter 5. Results and Discussion  which will reduce landfill stabilization and prolong the time necessary to complete the stabilization of the landfill. According to Knox (1990) between 5 to 7 bed volumes (a bed volume is the total moisture content of the landfill, including absorbed water and free leachate) of water will have to pass through most landfills receiving degradable wastes to reduce NHz — N levels to dischargeable concentrations (to reduce NHz — TV concentrations by three orders of magnitude within one generation). Calculation of flushing rates generated solely by percolation through clay caps have shown that it will easily take 500 years or more (Harris et al., 1994). This can not be considered sustainable. Six or more generations will have to lookout for our garbage. Landfill liners and leachate collection systems are designed for much shorter periods (30 - 40 years) than this. The potential for the failures in these structures pose a much greater risk to the ground and surface water than the generation, collection and treatment of leachate under controlled conditions. In the present work NHz-N  concentration were below 10 mg N / L after passing of  5-10 L / k g dry refuse. Vancouver landfill at Burns Bog is used as an example to demonstrate this in a practical situation. It is assumed that all the rainfall water was allowed to infiltrate through the refuse and that there will be no waste deposited on top of this 8 hectare area.  Calculation (Data were taken from Wreford, 1995 unless specified) Refuse deposited in the landfill during year 1992  471,000 tonnes M S W + 150000 tonnes D L C  Area used to deposit waste for 3 years  300 m X 800 m  Area used for one year  80000 m  M S W field capacity (Munasinghe, this work)  69 % wet weight  2  201  Chapter 5. Results and Discussion  = 24 % wet weight  Moisture at placement (Bird and Hale, 1976)  45 % wet weight  Additional moisture that can be absorbed  Amount of moisture that can be absorbed to MSW= 471,000x1000x45 % kg = 21195xl0 kg 4  = 211950 m  3  The waste was spread over an area of 80000 m  2  Infiltration required to reach the field capacity  = 211950/80000 m = 2649 mm  Annual rainfall for Vancouver landfill  =1150 mm  Evapotranspiration for the Burns Bog area  = 639 mm  Time needed to reach field capacity  = 2649 mm/(1150-639) mm/year 5.2 years  Evapotranspiration is high in dry months. Most of the rainfall is during the rest of the year. Therefore available water is higher than what is assumed above and the time taken to reach the field capacity is less than 5.2 years. For the landfill to bring JVi/3-N below 10 mg/L the refuse will need to pass 5 - 10 liters of water through each kg of dry refuse.  Total weight of dry refuse deposited in year 1992  = 471,000 tonnes x 76% 357960 tonnes  Total volume of water needed to pass through  357960 x 1000 x (5 to 10) liters (17898 to 35796) x 10 liters 5  1789800 to 3579600 m  3  202  Chapter 5. Results and Discussion  Assuming the source of water is rain. This will fall over an area of 80,000 m . 2  Time taken to bring the NH -~N 2  to a level lower than 10 mg/L  = (17898 to 35796)xl0 m/(80,000x511 mm/year) 5  = (22.372 to 44.745) m /511 mm/year = 44 to 88 years after reaching the field capacity Total time since 1992  = 49 to 93 years  This shows that even if all the available rainfall was let to infiltrate through the refuse it will take 49 - 93 years to stabilize the landfill with respect to JVi7 -N. By providing 2000 3  mm/year infiltration rate (discussed in next paragraph) this portion of the Vancouver landfill at Burns Bog (filled starting 1992 over three years) can be stabilized within 12 to 23 years. The above calculation did not include 150,000 tonnes of D L C waste. Including this waste will bring the time span close to Harris et al. (1994). According to Harris et al. (1994) to reduce N H3 — N levels to dischargeable concentrations within 30 years, the mean hydraulic retention time must be less than 5 years. And for it to be effective, passing water must be reasonably uniform, reaching the whole of the waste mass eliminating zones of 'dead volume'. Irrigation rates equivalent to 2000 mm/year or more will be needed at many landfills.  Moisture in the refuse could be  distributed unevenly due to channeling; observed by Zeiss and Major (1993) and Zeiss and Uguccioni (1995). Channeling is the vertical flow of liquid through pores with cross sectional areas which are substantially less than the cross section of the top layer of waste where infiltration occurs. According to Zeiss and Uguccioni (1995) low infiltration rates are less likely to lead to pronounced channeling than high rates, because slow application of water will allow more time for the sorption into the refuse. Also capillary action in the waste layer may redistribute moisture so that the matrix flow regime in the waste  Chapter 5. Results and Discussion  203  layer may contribute more to the overall discharge. Irrigation rates of 2000 mm/year or more should be distributed throughout the year to reduce channeling and allow moisture to be distributed evenly within the refuse mass. Increasing moisture and moisture movement remains the most practicable method to promote stabilization and methanogenesis. Landfill operation practices like the addition of water for compacting the refuse increases moisture in the landfill. method of increasing moisture.  This is a good  As it does not give sufficient moisture it has to be  supplemented with another source of moisture. Recycling of leachate is the most common method used to improve methanogenesis and stabilization. This also increases moisture and moisture movement. Nutrients will be retained in the landfill. Leachate recycling stabilizes landfills with respect to degradable organic compounds but increase in other inorganic compounds is observed over time. Increased inorganic compound concentrations could lead to toxic levels and completely inhibit microbial activities over time. Landfills cannot be considered completely stabilized until the pollution threat to ground and surface waters are completely eliminated. Soluble compounds in landfills should be converted to gaseous or liquid phase and transported away from the landfill so that these are not mobilized at a later date and pose a risk to the environment. Leachate recycling will not achieve this. Problems associated with leachate recycling such as odor and biological clogging of recharge wells which have forced abandonment and storage of leachate requiring leakage proof facilities has made it unattractive as an alternate method for increasing moisture and moisture movement. Leachate recycle involves pumping which adds to the cost of operation. With enhanced gas production this energy requirement could come from landfill gas.  Even if all the  problems associated with leachate recycle are overcome it does not bring the landfill releases to a level that will allow for uncontrolled release. Precipitation and moisture at placement are the main sources of moisture available  204  Chapter 5. Results and Discussion  for landfills. The seasonal variation in precipitation can cause problems if uncontrolled infiltration through the refuse is allowed. In reference to the Pacific North West; 1. High precipitation season coincides with the colder season; cooling of the refuse mass could impede methanogenesis and therefore high organic carbon levels appear in leachate. 2. During warmer months there could be reduced infiltration through the refuse mass which in turn reduces nutrient transport, by-product removal etc.. This is the time during which higher stabilization could be achieved with warmer temperatures available. 3. Uncontrolled high infiltration will promote channeling of water through refuse leaving moisture deficient zones. Wall and Zeiss (1995) suggest an alternate approach for landfill design; addition of moisture to stabilize the landfill faster. But the questions "How much moisture should be applied?" and "How will it be done?" arise. From the work of Leckie et al. (1979) it was seen that continuous water infiltration enhances methanogenesis. This research supports the study by Leckie et al. (1979) in that continuous water infiltration enhances methanogenesis. Infiltration rates as high as 170 mm/day (column 18) can be applied to landfills while enhancing methanogenesis. But caution should be taken not to introduce cooling effects with the applied water and landfill operation should address the nutrient availability. Introducing oxygen with increased infiltration did not seem to have an effect on the results of these column experiments.  The refuse columns were 1.4 m in height.  Normal landfill heights are at least an order of magnitude more. Therefore, any oxygen that is introduced with increasing water inputs should be readily consumed by aerobic bacteria in the top most layers.  Chapter 5. Results and Discussion  205  Decreasing H R T by increasing infiltration to enhance methanogenesis raise the concerns about leachate treatment. With high infiltration one would expect high volumes of leachate to deal with. In most of the present landfills all the rain water that falls on the landfill premises is collected and treated before discharged. This rainfall gives peak flow rates during winter months. Decreasing H R T will not be economically feasible if importing water from other sources is intended. Decreasing H R T should be managed with the available water in the site in which case volume of leachate to be treated will be the same. Also peak flow rates will be damped out by passing through the refuse. Towards the end of the study period some of the columns showed a decreasing trend in CH4 production rates.  Barlaz et al. (1989) also observed a decrease in CH4 pro-  duction in his cells with leachate recycle. They discounted absence of microorganisms, toxic carboxylic acids, and cation concentrations and an ammonia limitation. From this study it was also seen that toxic levels of carboxylic acids or cation concentrations were not the cause of the decrease in CH± production as they were low during the periods of decreased CH4 production. With time, available nutrients could become limiting for the biodegradation and hence decrease in gas production. But in this work T K N concentrations towards the end showed that nitrogen could not be the limiting factor. Data showed that in higher H R T columns (15 and 17 in phase II) NHz — N increased for sometime indicating NH3 — N is released to the leachate faster than they are flushed out. In this research only after passing 5 - 10 L of water/kg dry refuse that NH2, — N were lower than 10 mg/L. Burns Bog landfill refuse will be 49 - 93 years old by the time refuse is flushed 5 - 10 L / k g dry refuse. Therefore, according to this research nitrogen was not limiting even with very low HRTs used. It could be that other necessary elements for biodegradation are beginning to deplete. If this is what is happening in low gas producing columns, there is organic carbon left that will not be degraded. This is a disadvantage when recovery of gas for energy is intended since the potential for gas production is lost.  Also after  206  Chapter 5. Results and Discussion  the gas production becomes very low, the diffusion of atmospheric air will create aerobic conditions further slowing the process. These observations show the importance of initiation of high gas production early in landfills. By providing moderate infiltration rates, nutrients would be retained within the landfill (compared to the high infiltration rates) while landfill stabilization is enhanced. In this work even with high flushing rates used T K N concentrations showed that nitrogen could not be limiting. Landfill management strategy should be carefully analyzed. If the landfill is to receive fresh refuse in layers over the years, it is unlikely to be deficient in nutrient or other necessary elements even if high infiltration rates are applied. In this case providing infiltration will carry the organic carbon from top layers to the layers at the bottom where methanogenesis is well established. According to Barlaz et al. (1989) polymer hydrolysis limited the refuse methanogenesis. In this work even though the CH  4  production rates were decreasing they were still  much higher than that reported for landfill. If the decreasing CH± production rates are due to the limiting hydrolysis, improving hydrolysis at this decelerated methane phase should be considered to stabilize the landfill faster. Starting leachate recycling at this stage could be an option which will provide lechate treatment as well as extra organics for the methanogenic population. The discussion in the Section 5.9 shows that carbon released from the landfill is highly dependent on the gas production of the system,  i.e.  an active microbial population  is necessary for the stabilization of a landfill with respect to organic carbon. Higher gas producing columns released 50% more carbon to the environment than the low gas producing columns. If the low carbon release from the low gas producing columns is due to depletion of necessary elements for biodegradation, low gas producing columns will give a lower CH4 yield than high gas producing columns. This is disadvantageous when the recovery of gas for energy is intended, since the potential for gas production is lost. It  207  Chapter 5. Results and Discussion  was also seen in this work that only 3% to 16% of the methane potential was recovered. By the end of the study period even though CH4 production rates were decreasing they were still high. Hydrolysis of cellulose would not have been completed.  Most of the  methane potential from cellulose and hemicellulose was not recovered. Implications of these in the real landfills would be that landfill gas recovery projects will not be as economically viable as they could be. Since the majority of the methane potential in a landfill is from cellulose and hemicellulose it is necessary to concentrate on hydrolysis process in the landfill. Therefore it is important to plan the landfill operation with the application of enhancement technology if the recovery of gas is intended. Also, the results of this study showed high CH4 production columns behave favorably. For example, column 6 had high CH4 production; when the H R T was increased in phase II, column 6 behaved differently than other two columns 15 and 17 (low CH4 production) that assumed the same HRT. Column 6 increased its pH which is favorable for methanogenesis, where as columns 15 and 17 decreased their pH. High CH4 production columns could maintain a higher alkalinity irrespective of HRT. Enhancement of landfill stabilization should concentrate on establishing a healthy microbial population at the very beginning. This will give faster stabilization, as well as a system that is not prone to failures due to unavoidable natural causes. The objective of this research was to see the effects of H R T on landfill leachate and gas characteristics. Although much effort went into creating 18 identical columns of landfill, decomposition in most columns was highly variable with a few exceptions. Some possible causes for the differences were explained in Section 5.3. These columns were carefully controlled to have identical enhanced methanogenesis.  Addition of anaerobic digestor  sludge must have helped in establishing methane production at the very beginning in the majority of the columns. But the extent of methanogenic activity was different from column to column.  Barlaz et al. (1987) also found that it was difficult to duplicate  Chapter 5. Results and Discussion  methane production in replicate containers.  208  This variability questions the ability and  reliability of control or enhancement of methanogenesis in real landfills where conditions are far from the ideal laboratory conditions.  Chapter 6  Conclusions and Future Work  6.1  Conclusions  H R T of landfills affects landfill gas and leachate characteristics. Based on the results of this research, the following conclusions can be made: 1. For unsaturated landfills: HRT  S = — Q  Where; S = Volumetric water holding capacity of the solid waste in the landfill X Volume of the solid waste in the landfill (L ) 3  Q = Flow rate through the landfill ( L r 3  _ 1  )  2. Tracer work also showed that as the refuse undergoes decomposition, H R T decreases.  This is reflected in the equation above since the water holding  capacity (S) decreases with the decomposition of the refuse. 3. Percent CH  4  concentration in gas decreases with increasing H R T up to 60  days. 4. Percent CH  4  concentration in gas did not show any significant effect from  increasing H R T beyond 60 days  209  Chapter 6. Conclusions and Future Work  5. Lower HRTs result in higher CH  210  4  concentration in the landfill gas due to the  following reasons; (1) dissolution of C0  2  into the increased leachate flow and  (2) Enhanced methanogenesis with the decrease in C0  2  partial pressure.  6. Comparison of CH production of columns with similar decomposition history 4  showed lower HRTs resulted in higher CH production than the higher HRTs. 4  7. The amount of carbon released (both in gas and leachate) to the environment is highly dependent on gas production. High gas producing columns released 50% more carbon than low gas producing columns giving a more stabilized landfill with respect to carbon. 8. Gas production itself helps in developing favorable conditions for biological degradation; it increases pH, produces alkalinity when VFAs are consumed, responds favorably to changes in H R T , and reduces inhibitive concentrations of VFAs. 9. The initial leachate pH was between 5.2 and 5.5. During phase I, high gas producing columns increased their pH, while low gas producing columns decreased their pH. High gas producing columns increased their pH irrespective of the change in H R T in phase II. A decrease in H R T helped low gas producing columns to increase their pH which is favorable for methanogenesis.  A  decrease in H R T during phase III for high gas producing columns decreased pH but no detrimental effect on gas production was observed. 10. Correlation of iron concentrations to pH and CH  4  dence on H R T and CH  4  production showed depen-  production stage of the columns.  11. Zinc concentrations showed unpredictable correlations to pH and methane production rate.  Chapter 6.  Conclusions and Future Work  211  12. T h e high organic carbon concentrations observed in field studies are not, based on this study likely to be due to the failure of methanogenesis because of high water inputs.  6.2  1  Recommendations for Future Work 1. In this research H R T was changed by changing the infiltration rate. T h e effect of H R T when changed due to the height of refuse, saturated and unsaturated depths of refuse and the density should be studied. T h i s w i l l help determine the most effective landfill designs to enhance methanogenesis. 2. Increase in organic carbon observed i n field studies could be due to the failure of methanogenesis as a result of the cooling effects introduced by infiltrating water. Studies that characterizes leachate and gas w i t h respect to temperature of infiltrating water w i t h different H R T s is necessary. 3. T h e concept of microenvironment needs further investigation; spacial distribution of microbial species and other relevant information. T h i s w i l l help i n understanding the landfill microbial environment and its strength. 4. Present landfill covers are designed to encourage surface runoff. Increasing i n filtration  through the landfill w i l l enhance biodegradation. If this is intended,  encouraging infiltration through the covers w i l l have to be done. Therefore, design of covers to promote high infiltration would have to be investigated. 5. Investigation of intermittent flow and therefore variable H R T i n landfill lysimeters w i t h tracer studies is necessary to see how water progresses through refuse columns i n real landfills.  Bibliography  [1] A P H A (American Publish Health Association), American Water Works Association and Water Environment Federation (1992), "Standard Methods for the Examination of Water and Wastewater", 18th Edition, A P H A , Washington, D . 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Uguccioni (1995), "Mechanisms and Patterns of Leachate Flow in Municipal Solid Waste Landfills", Journal of Environmental Systems, Vol. 23 (3), pp 247-270.  Appendix A  Calculation of COi produced and Total Gas Production  When microbes produce CO2 they excrete it in dissolved form. Outside the microbial cell, infiltrating water provide the media for carrying dissolved carbon dioxide. When carbon dioxide dissolves in water it forms a weak acid, carbonic acid (H2CO3),  which  dissociates to give bicarbonate and carbonate ions. Only a small fraction of dissolved CO2 forms carbonic acid and, depending on pH, four forms can be present, namely, CO2, H 2 C O 3 , HCO3  , and C O 3 . Dehydration of CO2 will release C O 2 as gas.  It can be seen from the calculated gas productions in Sections A. 1.3 (method 1) and A.1.6  (method 2), 14529 ml/day and 8819 ml/day respectively are much higher than  measured gas production 3282 ml/day. Methane production for this day is 2373 ml/day. This gives CO2 productions of 12156 ml/day 6446 ml/day for method 1 and method 2 respectively.  This is not close to the methane production, which is expected when  methanogenesis is established. These errors could be due to the following discussed. According to Covington (1985) hydration and dehydration of CO2 is surprisingly slow. In the landfill lysimeters with the contact time available it is very unlikely that equilibrium conditions were achieved before leaving the lysimeters. Therefore use of Henry's law for calculating CO2 dissolved could be erroneous. But it was assumed otherwise. Also all the other equations used in the calculations assumes the equilibrium conditions of the system. Leachate leaving the lysimeters would not have achieved the equilibrium by the time pH and alkalinity were measured. Therefore the errors in assuming equilibrium conditions is larger for low HRTs. This can be seen from the Figures A . l to A.8. The  219  Appendix A. Calculation of CO2 produced and Total Gas Production  220  difference between measured and calculated are higher for low HRT. Both methods used assume that the alkalinity is only due to bicarbonates. For the period in method 1 this assumption should give little errors. But for the period when leachate was stronger this could give larger errors. It can be seen that the calculated carbon dioxide produced is far from the real carbon dioxide produced. Therefore calculated gas production was not used in any of the data analysis.  A.l  C0 Produced 2  Carbon dioxide dissolved in the leachate were estimated using two methods and are presented in Sections A.1.1 and A.1.4.  A.1.1  For Samples with Low Dissolved Solids - Method 1  When the total alkalinity of a water is due almost entirely to hydroxides, carbonates, or bicarbonates, and the total dissolved solids is not greater than 500 mg/L, alkalinity forms, free CO2 and total CO2 can be calculated from the Equations A.6, A.7, A.8, A.9 and A.10 (Standard Methods (A.P.H.A. et al., 1992)). Since the dissolved solids in most samples were higher than 500 mg/L, this method was used only for columns 1, 2, 3, 4, 12, 14, 16 and 18 for the last few sampling days where dissolved solids were less than 500 mg/L. Calculated gas productions for those sampling days are shown in Figures A . l - A.8.  Bicarbonate alkalinity as mg CaCOz/L  Where; T = total alkalinity, mg  CaCOz/L  =  T - 5.0X10  (pi/  -  10)  1 -f0.94X10(^- ) 10  (A.6)  221  Appendix A. Calculation of CO2 produced and Total Gas Production  Carbonate alkalinity as mg CaC0 /L  = 0.94XBXlO  3  (pH  ~  10)  (A.7)  Where; B = bicarbonate alkalinity, from Equation A.6  Hydroxide alkalinity as mg CaCO /L z  Free carbon dioxide mg C0 /L 2  = 5.0X10  (pi;r  ~  10)  = 2.0XBX10 ~ (e  pH)  (A.8) (A.9)  Where; B = bicarbonate alkalinity, from Equation A.6  Total carbon dioxide rag C0 /L 2  = A + 0.44(25 + C)  (A. 10)  Where; A = mg free  C0 /L 2  B = bicarbonate alkalinity, from Equation A.6 C = carbonate alkalinity, from Equation A.7  Note: Since pH in all the samples during the experiments were well below 8.3 total alkalinity was assumed to be equal to bicarbonate alkalinity.  A . 1.2  Sample calculation  For column 16, day 406;  Appendix A.  pH  Calculation of C0  2  = 6.11,  222  produced and Total Gas Production  Alkalinity  = 1512 mg as  CaC0 /L 3  Flow rate = 5.6 L/day, Gas measured = 3282 ml/day  Bicarbonate alkalinity (B)  = total alkalinity 1512 as mg  CaCOz/L  From Equation A.9 Free C0  2 X B X 10 "  (A)  2  (6  pi/)  2 X 1512 X l O "  mg CO2/L  0 1 1  mg  C0 /L 2  2347 mg C 0 / L 2  From Equation A. 10 Total  A + 0.44 (2B + C) mg C 0 / L  C0  2  2  2347 + 0.44 (2 X 1512) mg C70 /L 2  3678 mg CO2/L Equivalent C0  2  volume (ml)  = =*P  X Flow r a t e ^ X  3678 X 5.6 X 24.026/44 Total C0  2  A . 1.3  dissolved  11247 ml/day  Total Gas Produced Calculated from Method 1  Total gas produced = Gas measured + C0  2  = 3282 + 11247 ml/day = 14529 ml/day  dissolved  °-^^X  Appendix A. Calculation of CO2 produced and Total Gas Production  A . 1.4  For Samples with High Dissolved Solids - Method 2  In pure water at great dilution, the first dissociation; H  C O  2  Z  ^ H+ +  HC0  3  C H + X C  H  C  -  O  Ki = CH CO 2  Second dissociation; HC0  ^ H  +  3  3  + COf~  CH+X  C  K=  n  C  2  n  °  2 3  CHCOJ  For not pure water (sea water, leachate, wastewater)  a +Xa H  HCO  0-H CO 2  K  2  3  a +Xa 2co  H  =  HCO^  A  Where a is the activity. Apparent dissociation constants; H+XC -  A  HCO  a +XC 2H  C0  *2 =  O-H CO  — o-co X an o  aco  = Pco  2  2  3  2  2  2  X a  Q  Pco  — Partial pressure of  a  = Solubility of C0  2  a  2  C0  2  in pure water in moles per liter  224  Appendix A. Calculation of C0 produced and Total Gas Production 2  ajj o is unity for pure water and is depressed by the presence of salts in solution. In 2  these calculations au o is assumed to be unity. 2  Pco X  a Xa  2  Carbonate alkalinity = C  ~ +  0  H20  2C 2-  HCO  CQ  K'* =  Total CO2  — C  Cco  = a XPco  a  = solubility of C0 in leachate at 1 atm in moles per liter  2  - +C  (A.18)  3 r  HCO  s  s  A- Cco  2-  m 2  CQ  solution  2  2  For the pH range in the samples  C 2C0  could be assumed negligible.  Also it was  assumed that Alkalinity measured is only due to bicarbonates. But this is not really true for the initial leachate. Therefore calculated C O 2 produced for the phase I should not be taken as accurate.  A . 1.5  Sample Calculation  For column 16, day 406; pH  = 6.11,  Alkalinity  = 1512 mg as C a C 0 / L 3  Flow rate = 5.6 L/day, Gas measured = 3282 ml/day  Bicarbonate alkalinity (B)  = total alkalinity = 1512 as mg  CaC0 /L 3  Appendix A. Calculation of CO2 produced and Total Gas Production  1512/50000 mol./L Total  C0  ^ H C O ^ +" Ccoi  2  m  solution  From Table 23 in Harvey (1963); 0.0394 mol./L 0.277 atmospheres  PcOn  1512/50000 mol./L  CHCO~  1512/50000 + 0.0394 X 0.277 mol./L  Total CO2  0.0412 mol./L  Equivalent CO2 volume (ml)  0 . 0 4 1 2 ^ X Flow rate ^ X 0 . 0 8 2 ^ X 5.537 L/day  Total CO2 dissolved  A.1.6  5537 ml/day  Total Gas Produced Calculated from Method 2  Total gas produced = Gas measured -f CO2 dissolved - 3282 + 5537 ml/day = 8819 ml/day  225  226  Appendix A. Calculation of CO2 produced and Total Gas Production  • measured • method 1 • method 2  16000 ^  14000 +  P 12000 4c o o "O O a o ®  10000  2000 100  200  300  400  500  600  Time(day) Figure A . l : Comparison of Measured and Calculated Gas Production Rates for Column 1  100  200  300  400  500  600  Time(day) Figure A.2: Comparison of Measured and Calculated Gas Production Rates for Column 2  227  Appendix A. Calculation of CO2 produced and Total Gas Production  Phase  9000 -r  100  200  300  400  500  600  Time(day) Figure A.3: Comparison of Measured and Calculated Gas Production Rates for Column 3  600 Time(day)  Figure A.4: Comparison of Measured and Calculated Gas Production Rates for Column 4  228  Appendix A. Calculation of CO2 produced and Total Gas Production  Phase  9000 -r  100  200  300  400  500  600  Time(day) Figure A.5: Comparison of Measured and Calculated Gas Production Rates for Column 12  Figure A.6: Comparison of Measured and Calculated Gas Production Rates for Column 14  Appendix A. Calculation oiCOi  16000  T  14000 +  229  produced and Total Gas Production  • measured • method 1 • method 2  Phase  o 12000 "D  e  10000 4-  £  8000 6000 4000 2000 + 200  100  300  400  500  600  Time(day) Figure A.7: Comparison of Measured and Calculated Gas Production Rates for Column 16  50000 45000 S! 40000 D  measured method 1 method 2  5 35000 30000 £ 25000 •D 20000  Phase  O  Q- 15000 O 10000 5000 100  200  300  400  500  600  Time(day) Figure A.8: Comparison of Measured and Calculated Gas Production Rates for Column 18  Appendix B  Regression Plots for Iron and p H  20 +  120  +  5 PH  4.8  4.6  5.2  5.4  5.6  Figure B.9: Iron Vs pH for Column 1 -r  100 80 •&>  &  60  C  2 40 -y = -11.4 x + 140  20 --  SSE = 2395 F = 3.55, n = 21 Not significant —r—  0  5.2  5.4  5.6 PH  5.8  6.2  Figure B.10: Iron Vs pH for Column 2  230  6.4  6.6  Appendix B. Regression Plots for Iron and pH  Figure B.12: Iron Vs pH for Column 4  232  Appendix B. Regression Plots for Iron and pH  160  o  o  140 120 + _  _i  100 80  o  c  o  v  2 -  SSE = 22077 60  F=0.71, n = 21 y = 19.9 x -7.9  40 +  Not significant  20  +  —I  0  5.2  5.4  5.6  5.8  6.2  6.4  6.6  PH Figure B.13: Iron Vs pH for Column 5  250  -r  200 4-  ^ 150 + "&> E, c 2 100 4-  SSE = 50178  y = 42.2 X - 122.8  50  F=2.65, n = 21  Not significant —I  5.5  6.5 PH  Figure B.14: Iron Vs pH for Column 6  Appendix B. Regression Plots for Iron and pH  Figure B.15: Iron Vs pH for Column 7 140 y = -11.7 x + 149.9 120 --  SSE = 14121 F=0.47, n = 21  100 -  Not significant 80 --  *  o  o  40 20 -0 5.2  5.4  5.6  5.8  6.2  PH Figure B.16: Iron Vs pH for Column 8  6.4  6.6  6.8  234  Appendix B. Regression Plots for Iron and pH  Figure B.17: Iron Vs pH for Column 9 y = 14.8x-1.15 SSE = 5601  F=1.45, n = 21 Not significant  100 + 80  20 +  4.6  4.8  5  5.2 PH  Figure B.18: Iron Vs pH for Column 10  5.4  5.6  Appendix B. Regression Plots for Iron and pH  Figure B.20: Iron Vs pH for Column 12  236  Appendix B. Regression Plots for Iron and pH  Figure B.21: Iron Vs pH for Column 13 140  T  o  o  y = -21 x +162.7  120 --  SSE = 16125 100  F=1.1 n = 21 Not significant  ~5> 80 E p  60 40 -20 0 5.2  5.4  5.6  5.8 PH  Figure B.22: Iron Vs pH for Column 14  6.2  6.4  237  Appendix B. Regression Plots for Iron and pH  o -I 45  1  1  1  1  1  4.7  4.9  5.1  5.3  5.5  PH  Figure B.23: Iron Vs pH for Column 15 200 i  y = - 36.2 x + 304.2  180 160 -  R =-0.46 SSE = 20518  140 -  F=5.2 n = 21 Significant  120 £ 100 -  I  k 80 <  o o  o  o  o  °  o  o  60 40 -  o  20 0 5.3  1  5.5  —\  5.7  —I 5.9 PH  1I  6.1  —I 6.3  Figure B.24: Iron Vs pH for Column 16  1  1  6.5  6.7  238  Appendix B. Regression Plots for Iron and pH  Figure B.25: Iron Vs pH for Column 17  y = -20.5x + 164.8 SSE = 9530 F = 3.4 n = 21 Not significant  5.3  5.5  5.7  5.9 PH  6.1  6.3  Figure B.26: Iron Vs pH for Column 18  6.5  6.7  Appendix C  Regression Plots for Iron and Methane Production Rate 120 100 80 E, c o  60  y = 0.017x +47.19  40  F = 37.8 n=22  R = + 0.81  20  Significant  SSE = 3241  +  0 500  1000  1500  2000  2500  3000  3500  CH-4 Production (ml/day) Figure C.27: Iron Vs Methane Production Rate for Column 1  120 100 1 80 E, c 2  60 40 20  F = 2.1 n=21  y = -0.001 x+ 79.57  Not significant  SSE = 2653  0 2000  4000  + 6000  1 8000  h  10000  CH-4 Production (ml/day) Figure C.28: Iron Vs Methane Production Rate for Column 2  239  12000  240  Appendix C. Regression Plots for Iron and Methane Production Rate  Figure C.29: Iron Vs Methane Production Rate for Column 3  y = 0.01x +98.65 R = + 0.49 SSE = 14890  Significant  500  1000  1500  2000  2500  3000  3500  CH-4 Production (ml/day) Figure C.30: Iron Vs Methane Production Rate for Column 4  4000  Appendix C. Regression Plots for Iron and Methane Production Rate  Figure C.31: Iron Vs Methane Production Rate for Column 5  Figure C.32: Iron Vs Methane Production Rate for Column 6  242  Appendix C. Regression Plots for Iron and Methane Production Rate  20 -0  -I 0  1  1  1  1  1  2000  4000  6000  8000  10000  CH-4 Production (ml/day)  Figure C.33: Iron Vs Methane Production Rate for Column 7  Figure C.34: Iron Vs Methane Production Rate for Column 8  243  Appendix C. Regression Plots for Iron and Methane Production Rate  180  T  160 -140 -_  120  ^  100 +  |  80 +  _2_ O  60  *  O  40 + 20 0 0  500  1000  +  1500  o  F=0.13 n=23  y=  Not significant  SSE = 22555  +  2000  + 2500  H  3000  0.002X  +93.27  1 3500  1 4000  CH-4 Production (ml/day)  Figure C.35: Iron Vs Methane Production Rate for Column 9  Figure C.36: Iron Vs Methane Production Rate for Column 10  endix C. Regression Plots for Iron and Methane Production Rate  160  F = 7.4 n=23  140  Significant  120 100 "&>  E, c o  80 60 40 20 0 500  +  1000  +  +  1500  2000  2500  CH-4 Production (ml/day)  Figure C.37: Iron Vs Methane Production Rate for Column 11  Figure C.38: Iron Vs Methane Production Rate for Column 12  3000  245  Appendix C. Regression Plots for Iron and Methane Production Rate  200  F = 3.0 n=23  y = -0.012x +121.18  180 •  Not significant  SSE = 8239  160  : :  140 120 80 60 + 40 20  4-  0 500  + 1000  +  1500  2000  CH-4 Production (ml/day)  Figure C.39: Iron Vs Methane Production Rate for Column 13  Figure C.40: Iron Vs Methane Production Rate for Column 14  2500  246  Appendix C. Regression Plots for Iron and Methane Production Rate  y = 0.077x + 17.11 300 250  R = + 0.78 SSE = 72520 F = 33.4 n=23  200  Significant  c»  £ 150 c  s  100  oo  50 0  4-  500  1000  1500  2000  2500  3000  3500  CH-4 Production (ml/day) Figure C.41: Iron Vs Methane Production Rate for Column 15  y = -0.013x + 151.29  o o  R = - 0.47 SSE = 20841 F = 6.0 n=23 Significant  1000  + 2000  +  3000  + 4000  +  5000  6000  CH-4 Production (ml/day) Figure C.42: Iron Vs Methane Production Rate for Column 16  7000  247  Appendix C. Regression Plots for Iron and Methane Production Rate  y =0.086x + 33.33  0A 0  Significant  1  1  1  1  1  1  1  200  400  600  800  1000  1200  1400  CH-4 Production (ml/day)  Figure C.43: Iron Vs Methane Production Rate for Column 17  y = -0.01x + 69.68  140  R = - 0.64  120  SSE = 6861 F = 14.23 n=23  100  2  80  |  60  Significant  40  oo °oo  20 4-  1000  42000  +  3000  4000  CH-4 Production (ml/day) Figure C.44: Iron Vs Methane Production Rate for Column 18  5000  Appendix D  Regression Plots for Zinc and p H 1.4 j  y = -0.023x + 0.819  1.2 --  SSE = 1.1 F = 0.02 n = 22  1 --  Not significant  0.8 -E, o 0.6 -c N 0.4 --  o o  <x>  0.2 -0 -4.6  4.8  5.2  5  PH  248  5.4  5.6  Appendix D. Regression Plots for Zinc and pH  Figure D.48: Zinc Vs p H for Column 4  249  250  Appendix D. Regression Plots for Zinc and pH  1.4 y = - 0.32x + 2.18 1.2 R =-0.47 1  5  SSE = 1.1 F = 5.7 n = 22  i>8  N  Significant 0.6 +  Figure D.49: Zinc Vs pH for Column 5 12 ~r y = - 1.84X+ 12.19  10 +  SSE = 83.6 F = 3.88 n = 22 Not significant  0 5  £  o c  6+  N  6.5  5.5  pH Figure D.50: Zinc Vs pH for Column 6  Appendix D. Regression Plots for Zinc and pH  Figure D.52: Zinc Vs p H for Column 8  251  252  Appendix D. Regression Plots for Zinc and pH  y = - 1.98X + 13.39 SSE = 68.5 F = 4.3 n = 22 Not significant  Figure D.53: Zinc Vs pH for Column 9 4.5  T  4 3.5 3 -rib  E, ¥ Kl  2.5 2+ 1.5  °o  SSE = 28.1 y = 1.8x-6.53  1  R = + 0.47  0.5 + 0 4.6  4.7  4.8  4.9  + 5  5.1  —t— 5.2  F = 5.8 n = 22 Significant  —I—  5.3  pH Figure D.54: Zinc Vs pH for Column 10  5.4  5.5  253  Appendix D. Regression Plots for Zinc and pH  1.8 T 1.6  y = 0.39x-1.54  1.4  SSE = 2.8  1.2 4-  o o  F= 1.14 n = 22 Not significant  1+  g 0.8 N  Figure D.55: Zinc Vs pH for Column 11 3.5 -r y = - 0.21x + 2.54  3 --  SSE = 15.6 2.5 5*  F = 0.14 n = 22 Not significant  2 -  E  i^.5-N  1 --  o<><  0.5 -0 4.7  4.9  5.1  —f— 5.3  5.5  5.7  PH Figure D.56: Zinc Vs pH for Column 12  5.9  6.1  254  Appendix D. Regression Plots for Zinc and pH  Figure D.57: Zinc Vs pH for Column 13 0.9 -| 0.8 -  O  y = -0.21x + 1.44  0.7 -  SSE = 0.9  0.6 -  F = 2.56 n = 22  "cn 0.5 E, ¥o.4 N 0.3 -  Not significant  o  0.2 0.1 0 5  °  —-—•—  o  •  oo o  o  1  1  1  5.2  5.4  5.6  —I 5.8  o —— o o O—I  6  Figure D.58: Zinc Vs pH for Column 14  •  ^_>>  1  1  6.2  6.4  Appendix D. Regression Plots for Zinc and pH  25 y = -2.23x +16.23 20 4-  SSE = 440 F = 0.38 n = 22  •~ 15 + "o>  Not significant  E, o  R 10 4-  o-  5+  o <*>  ° 4.5  o  o  o  °  1  1  1  1  1  1  1  1  1  4.6  4.7  4.8  4.9 pH  5  5.1  5.2  5.3  5.4  Figure D.59: Zinc Vs pH for Column 15  25 -r y = + 0.54X + 1.85  SSE = 447.3 F = 0.05 n = 22  Not significant  20  IT 15 Oi  E, o  H 10 4-  '  <0 o  o o ° <> o v  5.2  o  o  <>  4  1  h  5.4  5.6  5.8  o  6  o  o  6.2  6.4  PH Figure D.60: Zinc Vs pH for Column 16  6.6  6.8  Appendix D. Regression Plots for Zinc and pH  Figure D.61: Zinc Vs pH for Column 17  Figure D.62: Zinc Vs pH for Column 18  256  Appendix E  Regression Plots for Zinc and Methane Production Rate  y = - 5.3E-6X + .72 Not significant  1.40 -r 1.20 _ 1.00 rr  o o  o  SSE = 1.15 F = 0.01 n=24  o o  |> 0.80 4"g 0.60 N 0.40  o  0.20 4-  +  0.00 500  1000  4-  4-  1500  2000  2500  3000  3500  , CH-4 Production (ml/day) Figure E.63: Zinc Vs Methane Production Rate for Column 1  1.20  y = - 6E-5x + 0.51  1.00  R = - 0.73 SSE = 0.65  0.80 E •B o c  F = 22.3 n=22  0.60  Significant  N 0.40 0.20 0  2000  4000  6000  8000  10000  12000  CH-4 Production (ml/day) Figure E.64: Zinc Vs Methane Production Rate for Column 2  257  258  Appendix E. Regression Plots for Zinc and Methane Production Rate  Figure E.65: Zinc Vs Methane Production Rate for Column 3  8.00  y = -0.00059X + 2.98  7.00  R = - 0.49  6.00 ^  SSE = 46.99  5.00  F = 7.18 n=24  4.00  Significant  0  500  1000  1500  2000  2500  3000  3500  CH-4 Production (ml/day) Figure E.66: Zinc Vs Methane Production Rate for Column 4  4000  Appendix E. Regression Plots for Zinc and Methane Production Rate  1.40  259  y = -7.2E-5X + 0.57  T  1.20  R = - 0.58  1.00 +  SSE = 0.95 F = 11.33 n=24  o) 0.80 + o E  0  Significant  1000  2000  3000  4000  5000  6000  7000  8000  CH-4 Production (ml/day)  Figure E.67: Zinc Vs Methane Production Rate for Column 5  12.00 -r  y = -0.00043X + 2.82  R = - 0.41  10.00  SSE = 83.58  8.00 rr £ o c  F = 4.5 n=24 6.00  Significant  N  4.00 2.00  1000  2000  3000  4000  5000  6000  CH-4 Production (ml/day) Figure E.68: Zinc Vs Methane Production Rate for Column 6  7000  Appendix E. Regression Plots for Zinc and Methane Production Rate  y = -2.3E-5X + 0.21 R = - 0.53 SSE = 0.26 F = 8.1 n=23 Significant  2000  4000  6000  8000  10000  CH-4 Production (ml/day)  Figure E.69: Zinc Vs Methane Production Rate for Column 7  Figure E.70: Zinc Vs Methane Production Rate for Column 8  261  Appendix E. Regression Plots for Zinc and Methane Production Rate  y = -0.0012x+ 4.76 R = - 0.63 SSE = 50.6  500  1000  1500  2000  2500  3000  3500  CH-4 Production (ml/day)  Figure E.71: Zinc Vs Methane Production Rate for Column 9  Figure E.72: Zinc Vs Methane Production Rate for Column 10  4000  262  Appendix E. Regression Plots for Zinc and Methane Production Rate  y = -0.00018x+ 0.73 R = - 0.45 SSE = 2.36 F = 5.72 n=24 Significant  500  1000  1500  2000  2500  CH-4 Production (ml/day)  Figure E.73: Zinc Vs Methane Production Rate for Column 11  Figure E.74: Zinc Vs Methane Production Rate for Column 12  3000  Appendix E. Regression Plots for Zinc and Methane Production Rate  Figure E.75: Zinc Vs Methane Production Rate for Column 13  Figure E.76: Zinc Vs Methane Production Rate for Column 14  263  264  Appendix E. Regression Plots for Zinc and Methane Production Rate  25.00 y = - 0.00034X + 5.55  20.00  SSE = 449 F = 0.12 n=24  1J 15.00 + cn  Not significant  E, o  o  R 10.00  o  oo  5.00 +  -35O  0$  «  0.00 500  +  1000  o o  1500  +  2000  2500  +  3000  3500  CH-4 Production (ml/day) Figure E.77: Zinc Vs Methane Production Rate for Column 15  25.00 T  y =-0.00147x+ 11.72 R = - 0.44  20.00  SSE = 363.2 F = 5.34 n=24  =d 15.00 cn  |  Significant 10.00 +  2000  2500  3000  3500  4000  4500  5000  5500  6000  CH-4 Production (ml/day) Figure E.78: Zinc Vs Methane Production Rate for Column 16  6500  Appendix E. Regression Plots for Zinc and Methane Production Rate  265  3.00 j y = 0.000162x + 1.48  2.50 -2.00 -Oi  £ 1.50 o c N  SSE = 3.4  1.00 4-  F = 0.9 n=24 0.50 Not significant 0.00 200  + 400  600  +  800  H  1000  1 1200  CH-4 Production (ml/day)  Figure E.79: Zinc Vs Methane Production Rate for Column 17  Figure E.80: Zinc Vs Methane Production Rate for Column 18  1400  Appendix F  Leachate Characteristics Data  F.l  pH  Leachate pH Column # Time Date (day) 0 6/10/93 14 20/10/93 17/11/93 42 1/12/93 56 70 15/12/93 84 29/12/93 98 12/1/94 112 26/1/94 2/9/94 126 2/23/94 140 3/9/94 154 3/23/94 168 4/6/94 182 4/20/94 196 5/4/94 210 6/8/94 245 6/29/94 266 8/10/94 8/31/94 9/28/94 10/19/94 11/16/94 12/23/94 1/11/95 1/18/95 1/25/95 2/1/95 2/15/95 3/1/95 3/15/95 3/29/95  308 329 357 378 406 443 462 469 476 483 497 511 525 539  9  10  11  12  13  14  15  16  17  18  5.51 5.60 5.63 5.65 5.70 5.59 5.56 5.41 5.51 5.33 5.39 5.27 5.41 5.49 5.81 6.25 6.37 6.09 6.70 6.40 6.48 6.95 6.51 6.79 6.40 6.70 6.30 6.92 6.25 7.14 6.30 6.42 6.40 6.14 6.17 6.26 5.97 6.05 6.16 6.00  5.54 5.52 5.63 5.53 5.59 5.51 5.55 5.43 5.51 5.38 5.46 5.38 5.44 5.39 5.41 5.41 5.29  5.47 5.49 5.53 5.51 5.55 5.37 5.44 5.34 5.41 5.26 5.33 5.21 5.30 5.14 5.14 5.27 5.24  5.43 5.43 5.43 5.43 5.46 5.38 5.29 4.98 5.00 4.76 4.87 4.72 4.90 4.77 4.75 4.74 4.66  5.49 5.53 5.51 5.56 5.58 5.48 5.60 5.45 5.49 5.29 5.33 5.15 5.35 5.18 5.18 5.08 5.04  5.49 5.52 5.56 5.52 5.59 5.43 5.56 5.44 5.50 5.30 5.33 5.08 5.10 4.92 4.88 4.80 4.78  5.48 5.47 5.43 5.41 5.46 5.37 5.31 5.19 5.18 4.89 4.99 4.81 4.90 4.79 4.76 4.75 4.66  5.52 5.46 5.40 5.39 5.43 5.30 5.40 5.28 5.39 5.18 5.26 5.17 5.32 5.21 5.25 5.34 5.56  5.27 5.24 5.31 5.29 5.36 5.32 5.34 5.22 5.29 5.07 5.14 5.03 5.08 5.03 4.96 4.87 4.70  5.42 5.41 5.40 5.39 5.41 5.34 5.43 5.30 5.60 5.51 5.74 5.90 6.00 6.20 6.33 6.37 6.47  5.35 5.30 5.28 5.33 5.42 5.39 5.46 5.28 5.35 5.09 5.14 5.01 5.13 5.02 5.00 4.99 4.85  5.45 5.45 5.32 5.46 5.49 5.48 5.44 5.33 5.48 5.33 5.52 5.64 5.74 6.03  5.54 6.00 6.45 6.71 6.57 6.36 6.30 6.40 5.16 6.12 5.97 6.19 5.95 5.97  5.55 6.02 6.47 6.48 6.50 6.37 6.37 6.26 6.23 6.17 6.10 6.16 6.11 5.88  4.67 4.70 4.70 4.84 5.02 5.23 5.37  4.90 4.86 4.71 6.39 4.95 5.12 4.69 6.01 5.05 5.45 4.71 6.00 528 5.89 4.77 5.98 5.58 5.99 4.77 5.95 5.53 5.77 4.78 5.84 5.82 5.92 4.82 5.92 5.90 5.71 4.98 5.97 5.83 5.83 5.03 5.90 5.91 5.79 4.91 5.81 5.76 5.66 5.19 6.00 6.02 5.63 5.32 5.95 5.90 5.77 5.55 5.24 5.69 5.89 5.49 5.58 5.79  4.65 4.61 4.60 4.59 4.60 4.62 4.68  5.41 5.48 5.47 5.48 5.53 5.44 5.51 5.40 5.54 5.37 5.56 5.37 5.40 5.30 5.37 5.82 5.49 4.93 5.42 4.92 5.80 5.08 6.49 5.15 6.45 5.53 6.54 6.07 6.55 6.14 6.49 6.06 6.21 5.95 5.94 5.90 5.90 5.94 5.95 5.89 5.89 5.75 6.07 5.72 6.13  5.39 5.45 5.50 5.55 5.63 5.60 5.72 5.61 5.68 5.53 5.58 5.52 5.52 5.39 5.40 5.57 5.66  3  4  5.48 5.46 5.47 5.52 5.58 5.51 5.57 5.43 5.46 5.36 5.39 5.22 5.21 5.05 5.02 5.01 4.71 4.70 4.68 4.76 4.85 4.79 4.65 4.81 4.93 4.95 5.07 5.30 5.20 5.23 5.58  5.41 5.47 5.55 5.50 5.54 5.50 5.51 5.29 5.36 5.16 5.23 5.21 5.28 5.30 5.33 5.73 6.03 6.46 6.33 6.35 6.25 6.27 6.15 6.18 6.01 6.02 5.72 5.92 5.94 5.85 5.84  5.49 5.50 5.70 5.65 5.66 5.63 5.65 5.50 5.58 5.42 5.46 5.39 5.38 5.34 5.38 5.36 5.22  5.46 5.43 5.49 5.47 5.53 5.49 5.60 5.45 5.46 5.32 5.40 5.38 5.36 5.27 5.22 5.13 4.96  5.19 5.39 5.66 5.64 5.69 5.73 5.88 5.81 5.80  8  6  2  5.19 5.16 5.20 5.12 5.22  7  5  1  266  6.38 6.34 6.32 6.62 6.11 6.12 6.10 6.00 5.94 5.89 5.88 5.91 4.62 5.95 5.91  6.32 6.43 6.31 4.83 6.45 4.79 6.54 4.77 6.33 4.75 6.35 4.72 5.96 4.76 5.89 4.80 6.00 4.78 5.98 4.92 5.94 5.01 5.83 5.04 5.82 5.03 5.83 5.23 5.74 5.24 5.78  £»  co  a> c\)  CO  •«r co SJ  O)  CM  CM  Tf  cn  Tf  s  CO  Tf  Tf  CO  cn S> 9> 9? cn CO  Tf  Tf  10  Tf  CD  Tf  Ol  3032 2766 2748 3081 3015 2332 1378  3336 2665 2316 2047 1860 1862 1475 1009  3018 2993 2837 2542 2658 2373  1061  1299  1768  Tf  oo cn 0  CM  CO  O)  Tf  0I78 |  cn  5429  CM  3 1492  5148  2497  3186  4303  4730  5422  5479  1353  1779  4940  2395  0  1823  1997  2702  2888  3481  3564  3456  4325  2784  5690 5115  7250 6855 5948  5290 5350 4568 3911  5830 4471 4229 2836 1742 1742  5226 4995 4144 3417 3378  3861  5520 5231  6386 6218 5379  2842  Tf  hco LO h- h-  co  LO  O)  CO 5) co CM s co § CM O) Tf  hco  1063  1807  1882  0 CO f- fCM co co co h. O) 0 co co Si *cn cn co T f co 00  00 0 00 CO Tf  1148  1638  2506  1908  1634  2062  4977  3826 2854  2390  4929  2560  2192  4198  Tf f-  LO  0  o>  CO  t cn  Tf  Si  co  01  fLO CO  Tf  O)  Tf f-  co  CM  3  cn  i  £»  Tf  s co co co hi co CO  CO  0  co CO  CM  co TJcn co  Tf  hi co 1 0 £ co o> h.  h-  CO CO  3  00  co  Tf  Tf  LO  cn 00  0 CM O  0 Tf  CO  CO  O)  CM  co  CJ)  co 0 0 T f S! co co CO cn in h-  co  CO  s i  co CM cn hcn LO co CU cn h. CO LO co h00  o> h-  CM  Tf  co  CM Tf  CM CO  1587  r- h-  3606  4236  3374  5690  3770  5101 4481 CM  4467  5334 CO  5899  7029  6181  7531  2240  7431 1194  5526 5652 1438  4644 6706 7497  4413  3447  3995  1269 4023  1194  3000  1314  5176  3375  1438 3695  1329  2004  3947  2963  4357  2046  2830 2525  1800  2498  2319  2867  3946  4160  3612J 2778  1479  3053  4495  3935 3084  1954  3408  50201 5243 4118 3462  3260  3923  5655 5060  1433  3555  3775  6350 6010  7160| 6450  9040  2617  4440  4695  3254  3489 3193  6233  6855  0 0 0  O)  CM  5 0 CO 0 CJ)  h-  Tf Tf  CO 0 LO  cn cn h- co co  Tf  0  0  CO 0  LO  8  h- cn O) f h. co  Tf  O)  82 cn 9? 9> cn — co  LO  co r- CM T f f co co co  LO  1—  rLO  CM  h.  cn cn  00 Tf CM  Tf  CM  0  10  co co  r- co 0 co CO CM  co  h-  f10  Tf  LO  CM  CO  co co hh00 O) Tf  Tf  LO  Tf  cu  co co cu LO  cn  Tf  CO  h.  Tf  LO O Tf  CM  0 CM CJ) Tf  0 O  CM LO  co Tf  O  co O  co CO  CM CO  co  CO O)  h- CM co co 00 0 CO LO  O  co Tf  10 Tf  cn co co O) LO 0  co co  CM  o> co  Tf  10  LO cu hco co co co co co 1 1 co CM CM cn  Tf  co  LO  10  LO 00  CM  LO  O)  LO  s  LO  LO  3/29/  3638  3639  3241  2279  1802 2670  4508  3677  6495  7195  5940  7440  6650  7380  t  3/15/  4015  2798  3009  4731  4210  7765  8588  7585  7105  9650  CM CO  CO  1028  3602  3053  2842  3315  2553  2037  2555  3748  6890  9100  LO  Tf  h-  2/15/  co co  CM  cn  LO  CM  I 1/25/  LO Tf CM  CM  CM  CM LO  1/11/  co co cn  lO  0 0 CM  cn  12/23/  2917  2870  3053  5693  4790  4480  9930 10950  10090  7860 10700  10810  7800 10100  7480  LO  10  11/16/  2614  3244  3200  4051  4508  3290  5318  5540  4840  5625  6500  7780  co  0  1152  2858  3668  3773  CM  4478  5365  5870  5670  f» Tf CO  Tf  CM  1777  3373  4381  5343  CO  7483  3600  3230  5695  Tf 00 CO  hO  CM  co  10/19/  CM  LO  2300  5410  c» co co Tf  5685  4785  7650  7150  CM  co co c- CM  2713  5520  4885  5105  0 Tf  4955  5950  7310  CO  2695  6125  5120  Tf CO CM  6320  7750  7660  10  LO CM  h.  Tf O  9/28/  0  2992  8450  6150  0 CO LO  CM  3120  9100  8020  LO Tf  6350  7400  CM  8300  8940  co  LO  cn  8/31/  co CM co a co co O)  3532  3693  3263  3294  3648  3788  4193  5048  5675  5910  6800  10190  28990 22290 29080 28110 30270 29680 27980 33170 30880 35220 35250 51940 31450 53260 30160 29410 29260 33480 15940 13040 11370 11910 13640 13560 11900 10890 11170 12320 15790 12550 13250 14390 12340 11230 15970 10860  CM  10 CO CM  I 7/27/  0  0  6/29/  CM co 0h- co co o> i— co LO CM  > co o •* co CO  5/25,  o  4/20,  CO  I 3/23,  Tf  2/23/  LO  2/9,  CO  26/1/9^  O  30540 32340 35670 30250 34130 27370 28770 29420 27870|  CM  I  CO  31710  co  15/12/93  co  44570 30880 36390 28310 35820 40230  LO  117/11/93  CM  23630 34300  co  120/10/93  Time (c  r»  6/10/  Date  %  Columr co  90S I.  /FA(mg  F.2  0068  _g  Leacha  Appendix F. Leachate Characteristics Data 267  Volatile Fatty Acids  LO CM  Tf  co  co Tf 0 CM  oo co cu  0!  co  0 Tf  CO LO  0  0  h-  0  O  O) SP  1 Leachate Volatile Fatty Acids Distribution (mg/L) Column # VFA Type Date 8050! 130401 193801 147101 157401 13670| 14260| 16570| 16420j 15360| 13970| 16710) 15600| 17620| 12440 14190 12920 13910 10/6/93 Acetic 3750 5150 22501 47301 57001 31901 55701 31601 40201 30901 22501 18301 31601 29301 28701 53001 27801 5040 Propionic 1070| Iso-butyric 8260 11840 7880 Butyric 1 97201 152301 171401 118101 13500| 10890| 15750| 19080| 11970| 12560| 13490| 14580I 10600 9630 11120 1010| 15001 32701 Others 10701 Total 23630I 34300I 44570I 30880I 36390J 28310| 35820| 40230| 31710| 30540| 32340| 35670| 30250| 34130| 27370 28770 29420 27870 oo in  o  o  5)  LO  ^  o  o  0)  P-  o  o  •<*  G>  co  CM  T—  o  co  CM  o o> r-  o  co  LO  r*.  o co  o oo  o  co  O •f O)  o  o  CO  CM  o co  o  co  LO  oo  o  CO  o  LO 00  co  o  o  CM  oo  o  r-  0)  co  o  o  |  o  8 7820 1100  o  6870 | 8280 | 6830 | 1560 ] 1100  O)  o o  5690 | 6240 I | 1080  o  o  co  o  8 CM  | 5280 [ 7350 I 6340 I 5370 I 6420 | 6630 | 1850 | 1560 | 1220 | 1390 I 1060 1540 I 1720  o CO •*  o  co co  co co  o  o o  CD  o o 5> CO  CM  O 00 CM  O  Si  co  o  Si  o  CM  h-  o oo  co  0)  o  co  CO  roo  o  o  O O LO C CJ) CM  00  co  CM  O o CM  |  o o  CM  o O Si SI  o  o  LO  in <*  o  o  r-  LO  o  CO  CO  5200 | 4850 |  3850 | o o in co  3400 I 3150 |  in m co CM  o o o r-. LO  o o o o  r»  m  o  o o m  m co  in  in m  o  OS  o o o  CM  o  O  in co  3740 | 4335 I  4565 |  3490 | o o CM o m CM  m o co  o o  in co  m IS) M oo C i—  h-  LO  o in m CO  o m -a- oo  o o  cn co  CD  o o co  co  o co in  h-  o o  in  7440 |  o 5625 | 7105 |  1750  1650  m  o  0)  co  in co  o o  4695 |  CO CM  in oo co  o  CM  O  a  CM O co CM  O  oo  CM  in cn co  O) CM  in  CO  O) CM  6890 |  in  5940 | 7195]  1220 4440 | 6010 |  1285  3120  3455  2640 3895 I 2130  6350 4465 |  6450  CM  5670 |  1150  o co  5695|  CM  m  4785|  CM  o  5120 | 6125 |  in rm CO  1185 P1750 [ 1875 | 1330 | 1685 | 1820 | 1750  LO  1280 I 1670 | 1120 I 1350 I 1510  2000 ]  3450  7160 3700  9040 4200  7380  2030  2660  1760  o  5655|  -<*  4955  CM  m in o  o  6320  m  in m o o o> co rm co CM  LO  5910  o  in LO co  3205 |  O in CM  o  o m  I  m  CM  m  1200  o  o  in O oo CM o>  CM  1645  o  o  in O co r~  in LO CO r»  1400  CM  3275 |  o  3075 I 3105 I  o  2500 2350  4850 |  8  O O CO  2845 I  o  00  o 2350 | 1700 I  4100 4500 o o o o o> CM  CO CM  10 CM  2735 I  6700 |  7860 10090  o o o in i*~  in  o  3450  3020 | 3180 | 1530 9930 8900  2780 |  2360 |  3390 1120  4550 1010  10860 3590 1290  0)  o o co  3200  3050  o o  I 1450 | 1600 1 1350 1 3000 1 2200 7800 I 10100 | 10700 | 9100 | 10950 | 9650 | 6650  2050 |  LO CM  1800 I 2150 I 1650 I 1650 I 2150 I 1650 I 1700 | 1900 f 1500 | 1150 I 1200 I 1100 I 1900 6800 8300 I 6350 I 6150 I 8450 I 7750 I 5950 I 7650 | 6500 ]  |  o  o o m  3750 [  o co  7780] 7 4 8 0 | 10810 I  CO  o o o o co co  7660 | 7310 | 7150 |  CO  OOS  O 0)  o  o  I  o  I  CM o  4000 1050  o 01 co  Si  3650 I  co  o  3350 I  0  00  3750 I 1050  CO  o  3950 I  o o in in  CO  8020 I 9100 |  CO  m  o  7400 I  o>  o  LO  8940  o  2380 | 3010 |  co co r- CM  2270 | 2140 |  o o  2550 |  o o  I  o  in rO) co  o 0) co  o o  |  I  co  I  o  m  o Si co  10190  CD LO  o o  o CO co  o o o in co  00  I  o  2330 I  5!  2690 I  o  2380 I  co  2630 I 2140 I  o  5450 | 4740 | 1160  o  O)  2380 I  r--  3960 | 5400 | 4160 | | 1170  f~  T—  o CO m  o o m o  SOS  3940 |  o o  o  CM  o  OOS  o  3550 j  15970  o 00 co  12340 11230  2820  4530  2450  4750  Si  o CO co  5830 I 4250 I 3350 I 4150 I 4150 | 3680 | 3100 | 1120 I 1250 I 1 1 1 0 I 1310 1 1080  5640 1430  8880 1630  6200 1800 o  3500 4580 I 4070 I 4000 I 3420 I 3490 I 3980 | 4050 | 4280 \ 3420 | 3040 | 3830 | 4470 | 3780 I 1010 I 2770 I 15940 | 13040 I 11370 I 11910I 13640 | 13560 | 11900p0890 | 11170| 12320 | 15790 | 12550 | 13250 14390  5580 1090 o  7250 1430  8  0989  0096 069  |  o  LO  0999  LO  o  o  LO  o •*  LO  Acetic Propionic Iso-butyric Butyric Others Total  IS)  14170] 10100| 14580| 15610| 15820| 13050| 24830 15340 22440 10580 13440 13030 14270 5150 4110 ] 3200| 3310J 2810 | 2170] 36401 4980 3250 6040 2690 4980 3730 1100 1610 1140] 1470 | 1190] 1300] 1910 9740 15080 10620 9820 8930 10780 10830 11460 10990 | 11310]| 11010 20030 2020 8090 5590 3880 2020 4560 | 4730 | 6250 | 3000 2680 29680 | 27980]| 33170 | 30880 | 35220 | 35250 | 51940 31450 53260 30160 29410 29260' 33480  Tt  t  o o co  o  12//29/93  CO  LO  LO  o 0> r-  Acetic Propionic Iso-butyric Butyric Others Total  0)  o oo  o  o co co  co  12/15/93  o co  o  O)  o co co  O  12/1/93 Acetic Propionic Iso-butyric Butyric Others Total  CM  in •*  O  I  co  o  Lo  LO  I  LO  o co  O) LO  Acetic Propionic Iso-butyric Butyric Others Total  o o  o  11/17/93  CO  8590 11410] 13240] 11190| 3510 ] 4140]] 3260 5230] | 1050' I 9690] I 10370 I 9880 | 10100]| | 2930 | 2110 I 3150 | 30270 | | 28990 22290 | 29080 I 28110  CD  o  11940 | 3610]  GO  Acetic | Propionic | Iso-butyric | Butyric I Others Total  F.3  10/20/93  Appendix F. Leachate Characteristics Data 268  Distribution of VFA types  5!  8  m O o m  3 h00  Tf  0) cn CM cn to T f co Tf Tf 10 Tf  Tf  co Tf  a> CO  Tf  in co co  3 CO  1  Tf  2778  8o  in CO cn  1234  o in  o  3612  2580  lO co co co oo o cn cn cn CM co Tf  m LO  1888  5243  o  to  4495  8 Ocn  1048  in in CO f CM  2933  to  5020  Tf  1125  2840  LO  OSS  00  2046|  269  Appendix F. Leachate Characteristics Data  o o CO o O) T f CM  h-  10  o in in o co CM o  3 in  in in O 01  in o  CM  h-  in  Tf  in in in co  3 CM O O  10  S  f-  co  m o o in in m i — to to CM co o> to m LO to co  i n i n co o co co i n co CM to CO  m in o m in o in i n to hTf i n i n CM to CM Tf  8  3  o LO O r- 0) CO co co  CM  ^  s  LO Tf Tf  8 CM in  Tf  s  I  CO 00 co cn f - CM co co co CM CM  LO CO co CO  o o  o cn co LO  s  co co 10 o o> CM in  O r-- CM o in co h- LO o co CM  £  i n oo Si o o i n co CM LO  to  CO o n CM cn ico co m  co i n co i n to CM T f oo CO co  CO 0) o CM CM co co co 0) 0) N- h- co T f co Tf Tf Tf CM CM T f  to o o h- CO lO CM  in  in o in o in in cn CO CO CO LO to to LO cn co  1  i n i n co o> CO o cn co T f CO  co co CM to  LO o co 10  CO  co m o oo o cn Si m co CO  co CM  a>  s3 T—  cn in  O  i  m to  1  co CO o m o o oo co o> i n to to m h~ CO CM  co CO o to  in m in m in in to CM CO co CO m LO CM in LO o i n o o o 1". o O) CM CO CM 10 CO in  10 co o o m oo co cn co in CM co o CO m o o fco cn co to co LO  | o8 oco co  o co co o> 10 co CM in  co o o a> CO m CM  co CO o fCM m CO  co co o cn o 0) r- co r-  to 8 oo co  o  o  o  o  Tf  m  s  lO LO o o  co  a>  in  o  s  O o O 0)  o co CM CO  i n 10 i n m o co CM h. Tf CO CO m in  CM LO i n i n i n LO LO o o co co CM  Tf  3  co  in o CM co CM  CM  LO co hCM  s  o i n LO m CM S CO o h- in  3 iCMn i n Tf Tf  *—  LO m i n 00 i — co CM co o o  CD CL  <  LL > c  E  o o Q1  u 'c o o 3 o XI  < Tf  1  o  38  1 CO  CD  2 6 & £ 3 O a. m  in  in in to in  1 .2  3  1  8 iCMn 1 s  8  s8 m  CO cn  co CM o CM  m h. co CM  ? co  8 iCMn v—  CO  cn  a>  o  Tf  h-  3m  8  Tf  LO  o .& o CO 3 XI 2-<5 £ O A — 3 O fm  1  CM  co o o m  Tf  Si cn co  to CM 00 CM  co 0) r>- to co co cn co co CO CO CM CO co cn CM co LO T f i n LO f ft to CM m CO  33  CO o o 00  CO  CO i n o oo 0) CM CO  CO to co  88 8  CO CO 0)  8o  Tf  o  Tf Tf  co o cn r-  3  333 8  8 *—3  8§  5!  CO 0)  8  Tf  CM  o Si co  a .2 1 Tf  co  8  o  o co  o  Tf  Tf  r3 oo  CM co co o m co co co cn CM Si co CM o co co T f T f h- o> h- 0> h- LO Tf to LO CM  5  3  co co co co co o i n i n Tf oo co o co  o o cn co T f T f co CO to o Tf 00 hin co Si m CM CO co  o  o>  oo oo co Tf h- o LO o Tf  8 to  to co Si co h- co h. co  CO cn co o CM  o  Tf  to 3 XI £ • CO 6 3 £ O m O  Tf  Tf  in  o  .&  3  CM cn T f 0) i n o o> Si hco  CO CO CM 00 i n O LO co f cn r- h- CO 00 CM  §  Tf  S  3  Tf  s8  in in  o 'c 0 o '•£3 CL o 0L  o> co T f O r- T f CM r-CM LO LO T f co CM CO  8  co  1^ 3 hCM  o o 'c o CO 0 o CD CL XI g 6 3 £ CL O m  1  to oo to Si o 00 cn CO o co to Tf CO T f CM CM CM co co  Tf  co o i n CM CM cn o T f h. co LO m 00 h- co CO CO co m o> CO Tf CM CO CM CM i n CO CO CM oo o T f o m m m O co LO CO m CO CO 00 o T f CM CM  CM  i n 10 co CM  m oo i n  to o co o CO 00 CO oo cn CO oo co co CO co CM  Tf Tf  O co o CO T f Tf co  CM  Tf  CM co T f CM 00 hcn cn Si co co CO 0) CM  8  co  3  o> to co co m CO m T f cn co cn CO i n o co O) m CM Tf  o tn oo co m T f CM CO  co i n o  o  3  Tf  cn to T f CO CM  h3 co  f»  to O) oo LO co co oo o i n co T f Tf co co co  Tf  8  o  88  3  h- o> O) CM Tf CO CM  3 ri n-  co LO o in to  Tf  LO o  8  Tf  O oo o to CO CM  8  co co o  JO  CM  co  8  co  38  Tf  Tf  CM CM  3  h- m o co CO to  co co co in co T f co  CM m  81  CM  h-  oo i n f - h- co CM o CM co CM O) Tf Tf Tf  oo Tf f-  i n co o to CM  co L0  O) cn CM co co m CO CO cn m a> CO CM Tf  Tf  co o cn m h- CO to o> co o o> to CM fo T f in m Tf CO co Tf hco i n oo co m o co co co to Tf Tf CM  co o  I  o c 0 o CL O CL  Tf  CM  m  m oo o m to  w  a>  3  0)  5>co  o  cn  CO cn 8 CO o ft 8 i CM  co i n co LO to to T f oo Tf CO  1  LO  f-  3 co CM  Tf 00 co co CM o r- o to co r*. to co o co o o co co CM Tf i n CM CO CM T f i n CM CM tn co i n CO  LO LO o i n i n o r- i n cn co m in O) CM GO CM Tf  r-  Tf  co tn o 0) co co oo CM in  8 co  CD  s  Tf Tf  CO CO to h- O) CM to  CO o h- f -  o  Tf  00 o co m o in m 00 m CM in  8s  CO  CM co o to a> i n CM CM  81  i n i n LO to oo co CO CM o cn cn 00 LO 0) CO CM oo LO co  8  LO s 8 CO O  o If) 00 hto cn to  o in o in m o co LO Tf o CM r- CM 00 m i n CO h-  5  oo o CO  co i n o m o co co  in  3  Tf  81  81  o  oo  1 Leachate Volatile Fatty Acids Distribution (mg/L)  Tf  3  m co o CO CO CM  Tf  f»  co CM co i n T f LO m  81mco 8 oo  10 cn CM CM CM fCO f-00 Si T f co CM CO CO  S>  f-  r3 oCO oo co  o co O r-- oo o CM  o o  co i n oo co i n oo i n hm CM LO CM CO co  3 sO CM CO  I  CM CM  co O m CO CO cn CO o CO  cn CO o LO 0) T f  10 o h- co co CM co  co CO co co r00 LO CM T f CO  in in i n m in in 00 LO f ~ t»Tf co co  35  co  8  r» 8 co L0  Tf  a  oo LO  CO CM  3 3 LO O oo co  m 8 co 3> to  1  o o 'c 0 o 3 o CL XI & 2 6 3 o_ tn m  Tf  cn gj CO  CO Tf  CO  1 o  cn h- CM o co CM co LO to  81CM Tf  3  CM co co co i n o 0> o CO to CO CO  Tf  Tf  3  3 mCO P2ft co  co co  a .2  co  LO  Tf  3 CM co  o o 'c o o 3 o to CD CL XI o 6 3 £ o O tn CD 1-  < Tf  CJ CO  Si co  a  270  c%O) co  cn  cn cn to 5>  tv CO tv  CM CM  CO CO tv co cn CM  in  co  co  cn  co co o CO  CO CM CM  cn to in o oo co co  CM tv m in o o co cn tn CM to - t 10 CM CM  co  in  CM  •c—  CO O)  CO  81  oo co O CM  in  CM  in  o  CM CM  co co  8! f~  1  o o  CM  r-  rv co  CM CM i v  s  co O O)  8  co co 00 tv i v CM co co  15 in  o oo CO •<* i v co o CM o cn oo o co  •* CM cn cn CM co oo o co oo co CO  ^-  tv co oo CD C\J 00 oo CO in m CM cn CM  o  o  tv o 0) co |v CM  CM  m  oo  co CM  CO co co oo CM  CO O i v CM  5 oo 15  in  CM  o co  co m CM 5  0) CM  CM CM  oo 10 00 co tv in o CO co O) co 0) CO  in  •* lO tv co co co co PI co oo CM CO CM CO  rv o> tv m CM co CM |v m CO CM  1269  03  1438  Appendix F. Leachate Characteristics Data  in  CM O  o  o o co  m in  00  CM IO CO IO  CO  cn 10  oo cn o CM CM  in  CM CD  i  s s  o  s in  in  CM  CM  o o o cn  in oo o oo  CM |v cn CM co co  m o o  O  |v |v |v CM |v  cn  ft! •<t  tv CM  CO  o Si  0) m o  CD co oo O) co in co co co in |v 8i |v cn  co oo co o  m  o o  in cn  CO 00 IO CD o CO CM  CM  co  81 o  rv  O  m m  m  co o o o o CD  o cn CD co tv o |v  o  oo CM CO  IO 10  CO  co  co o cn  CM  CO  in  8  fv 0) •«t  CO CM cn co  co O) CM IV in co o co in o  co co PI  O O  |v  in  o co m o o co IV in oo  co  CM  |v  o m  m co o o in GO  |v co  CM  CM  co  CM  co O) co  in  0)  in co  o oo o m  CM co  CM CM  h. co Si CM m cn co co  co  0> m CM CO 00 CM  o CM  tv CM cn co CM oo cn co o co CM  CO  co  o  s  co m in  o  oo  CM O) CM  in  00 o CM CM CO CD m CM o CM  a  co o co CO cn  o 00 in CM  CO  I  co o |v o oo oo m CO pi cn  CM  co  CO CM  tv  co  co  o  in  I  o cn  O co co co cn cn tv co oo CM  o  ca Q  8!  cn 5  CM  in  CM  o  3  & co  co co  s CM  in  CO 0) tv co tv  81 m CM  co oo  55 co IO  m  co  CO CO  3  oo  CO  in t-. cn co co tv CO co CO  IV co O CM o co CO m CM  |v 00 cn o o cn co PI 00 tv cn PI 00 co in  f|  in CO m ft! co in cn  0>  CM 0)  cn co oo co co CM in IV tv o m CM 5 o in  oo cn co CM in in in co  in fi! co co  r--  CM  o co •* co in in CM  81  s co  5) tv  |v cn CO  in co co  81 o co CM co |v CM 0)  in m o IV m  CO Si oo co  in  CM co pl o m CD CO CM  in o  o •>*  CO CO  cn CD o co co Si  co  in  co co cn  Iv CM CM |v  81  in  CM  in  00 o cn co o  O)  in in in co o in PI co oo IV oo CM  CO  IO co  o cn CM cn  co cn  co o cn cn tv cn m co oo CO  s  rv •<t  IV in Pi o o o PI co CM  oo o o o co o o > cn  co CO in cn CO in CO CM m cn co co co oo co •* in s IO co co cn o co 00 in  O) m CO CO CM 00 cn CO co CM CO oo Si oo CO in CM  00  CM oo CO o CO co CO co |v 00 CO co  s  tv •*  o o  |v CO CO r~ 00 Si in CO CO CM cn o co co co co oo in CO o o CO 0) co o CO cn CO 00 o co co  Iv Iv CO •<*• CO CO oo co CM 0) CO cn CO pi |v CM  00 CO o o o oo co CM 10  00 co o in o 00 o co CM co hi v CO cn m i— CM  o CO  co  co oo co oo 00 IS in  in  CM  o co  o o  Q.  fi  m  co  00 Si Si co co co •* CM |v CM  q> in CO co m co o in <* in •co  CD  3  CO  3  cn co CO co  to  % c  in -a-  o cn rv cn  CM  CO tv CO in  cn o tv co  LL >  10 cn  CO cn CO 00 co co O) co CM h» CO  CO 0) co O) •*  T~  <  oo  in in m in o>  o co CO co co •<* CM 0) CO in co co CM  CM CO  CM  o  1  o  CM •* 00 cn in |v i v CM in CO |v co co co CM  in O) o <£> to rv f- rv CM co O i — O i v in CO  co  8 tv  in in  tv CM lO CM in CO  in co  •<*  00 co  CM  CO  in  o  5  co CM O) co oo  CM CO  E  CM CM o O co  CO co 8! CO cn cn o m U) in  0)  1 Leachate Volatile Fatty Acids Distribution (mg/L)  8  CO  0  'c o  Q_ XI  12 S  6 tn  |v CO tv CO  lO  CM  T—  CO CD SZ  3 m  5  1  co  cn o co cn o  %  00 O)  cn |v o |v in  o  00  iv  o  r— •Q  cn  o  CM  •*r  81  co in CO co co co cn co co co  co co co CM cn in co oo co co co co  in  XI '!> CD I x: o 6 3 O CL tn CO  o Iv in co co o pi 0) co  00 CM  CM o oo oo IO CO co co cn r- co co CM  CO cn m o CM CM  CO 00  o o  co cn IO CM CM o cn o cn o 00 IO co m S co in CO co in CM  o m co  co  O)  CM  < 9? in  in  CO  co m co  m  CO  o  %  |  o o  'c S> o o 3 o CO CO CD Q. 3 Q. XI 1 x: S 6 3 £ 1 2 XI 3 5 0. < O tn m 0. 6 m  'E o o  CL  8  o  CO  —  •>» S! IO  S! IO  oo co co |v co  CM  CM  CD 00 rv 10 fv CM  oo CO o CM in |v oo Si o co cn m  CM  CM  s §  O  CO  o o  81  o co co co co oo oo o in co o> co cn IO 8 in CO |v m  oo oo co co  o  c & u o 3 o  1  o > tv  co  00 CO m m co in CO co CM  CO 0) CO CO m CO  co  o  o  in cn co co f- 50) CO co T-  CM co i v in o h- CO CM CO  CM  §•  00  o in o> o  CO  in  s 8 co PI co o co IO rv o  u  o  oo  CM CD CO CM o  0) oo oo ft! co Iv 0) in CM  1  x: 1 2 3 0- 6 O  CO  CM  o  |v  CO  3 XI  _co  CO  CD  m  CM co |v 5! m IO ID CO CM  5!  o  cn CM CM cn co IO co co  o  0  cn co  co CM  o  "c & o CL  in  o  8  < Ti-  en cn co  CO  CM |v  m  o in cn CO CM  o  'c  g CO 0 3 CD 01 X) s 6 3 x: 0. tn m o  1  271  i  T?  s oo  CO CM 0) T f 00  hco  LO  00  h-  co h-  s  CM LO CO 10 0) CO Tf  CM CO Tf  ft  co  o  CD  8  CM  oo CM 10  3 8, CO  cn co  3  Tf  CO T f CO CO CO T f  Tf  LO 00 CM  3 in  co  co h. CO co LO  in o LO r0)  00  to  10 CM  Tf  h- hcn Tf CM  CM Tf  co  3 co o  co  CO CO Tf  CM  CM  o o o o  co  O  Tf  h- co  8  co CO  CM  CM  in h-  oo o co ft! co o oo  SJ  8 CD o 81  O  o h. cn CO ft  co  Tf  CM  CO  o  Tf  CM  Tf  h-  |  | 1163  | 4481  | 1148  2695 | 3375 |  | 5101 5899  | 1402  O  o o cn  O  in  oo 8 h. co  CD LO LO  hco  O  CD  o  CM CD  CO T f  O  3O 3  Tf  5  in o co  in  CO CO  o i— o  1  Tf  Tf  O  CD  CO  h-  in  co 0)  o o  Tf  CO  CO  o o o m  00  ft  Tf  CD CO 0)  oo co o oo o o h- o CM LO LO  Tf  h. o o o o h-  CO  cn  CO  CD  co hin h- o co CM  CO CM LO  m  10  CO i —  Tf  00  |  3462 |  CM T f CM  ] 1396  | 3119  7029 |  5334 |  | 1472 | 1636  3259 j | 4118  1 6181 | 1194  o o o o o o  o o o o co  CM T f LO CO  | 7531  4550 I  1 7431  1 1570  | |  CM LO CO  CO  | 1438  I 1568  o o o o  8  co  SJ  Tf  co  CO h-  CO  3 CD  Si  8 co  CO  CO V - CM CM CO Tf  3 oCO  o o o  cn o o  CO CO  Tf  Tf  Tf  o o o  Tf  co in  o in  Tf  co oo  CO CM  Tf  CM  h-  Tf  o  O  CO  oo  O  Tf  CM CM  CO  00  CO  8>oCOo co oCM CM O  hi m  o  10 00  o> o  O)  CM  h-  o o  CO  3  co in  CM 00 CO  3  CM  Tf  CD CM  m o co  CM  CM CM CO CO  in  co co cn CO o in cn CM CM cn  CO CO  o  m in  Tf  cn in h-  8o  CO  CO CM  in co 00 CO  CM  h-  0) 10 CM CO  o o  3m Tf  co co h-  hi  co o o o o co  CO  co  o in o CM  00 CM CM  3 0)  CM  CM  3  Tf Tf  in co co CM  Si h.  co to o o oo co CM hin 0) Tf  o hco h- CJ> o co CO oo CM 00  o o o o co  CO CO 0)  co  | 1347  co co  00  CM  8  LO  CO  oo h- oo  CO  8 h-  o CO hco in CM  | 1028  h- co CM LO co  O CO  o  CO 0) CD  CO CD  o hco o co  Tf  o co  LO T f  CM  Acetic Propionic Iso-butyric Butyric Others Total  h- B! co h. cn  10  co co cn  h-  o  CD CO  LO  0) CO  o o o  11/16/94  3 cn COCOCO 3  o o cn hT f T f in r-  Tf  h- h- o oo m  co co  o o cn  I 1140  Tf  Tf  Tf  O)  (Acetic [ Propionic Iso-butyric Butyric Others Total  3 h-CM  oo  3  CO CO  cn 0) co h-  CM  110/19/94  co  3 LO  8O  o  o o o o  O  1264 I 1009 [ 1378  o>  LO 10  o  o h. o  CM CO  3  I  oo  1183|  14941  O  14981  Tf  CO  I 1152  CM  CM  co co oo co  1415|  | Leachate Volatile Fatty Acids Distribution (mg/L) 1 Column # 1 iDate 1 VFA Type 1  co  h-  Tf  | 7/27/941Acetic Propionic J Iso-butyric I Butyric 1 Others Total j  Tf  I  LO  CO 1— CO CO LO  2713]  h-  CO  0)  h-  Tf  oo 0) co  oo T f Bi o hcn co co  Tf  I Total  LO  h-  CO T f CO  cn oo  h-  CM T f  9/28/94 1 Acetic 1 Propionic 1 Iso-butyric Butyric Others  (O  co  Tf  LO  i  |I 1228!  o o o o o o  2658 j 1860|| 3081 | 1997  h.  o  h. oo  m  o  CO LO CO  2497 | 1148 \ 1063  co h-  Tf  CO LO  CO 00  o o o co  co B! co  CM  |  10  CO  CM 00  O  o  CO CM  CM  co  3  0)  2332 I 1492  10  0) CO co 3 3 CO CO  oo  co  co h-  in o o o o in  CO  1945 I 1475 I  s  CO 10 CO  co hco  cn o o o o cn  Tf  I  h-  co  co  o  Tf  o  cn o o o o cn  o o o cn  o o rco co h0) T f CO  Tf  Tf  CO  o o  1777  CM  CO  co  O  co B! oo  I  oo  5> 0)  co oo  O  o  10  in o o o o in  CM LO LO LO CM  | 3186 | 1882I 1807 | 1764 | 1109  co  oo  | 2373 | 1862 | 3015 | 1823 | 1150 | 1189  o o O) o oo Tf  CO  2300  CM CO LO  0> CO  s  LO T f  I  o o o o o o  LO LO CO  C^  CM  | 1560  |  o CO h. oo  co cn o o h-o T f  Tf  io co CM  I Total 8/31/94 I Acetic 1 Propionic 1 Iso-butyric 1 Butyric 1 Others I Total  LO CO  CM LO  oo o  o o o o o o  I  o 5 £3  0)  CM  | 1218:  ft oo  CO CM  Tf  CM  2240 3735  4428]  3o  | 1497  5652]  o o o o  1—  | 1345 | 1215!| 1509  h-  CO CO  |  LO  |  00  LO  CM  s co o 3  1935| 10011  CD  LO CO  3  cn cn  7497j  co h- h. CO  1409|  h- h3 o>  o  CO T f  O  8/10/94]Acetic Propionic ] Iso-butyric Butyric Others  ^  o o o o  I  CM  o o o o  CM CO  Tf  1638]  co  LO  CM  2506j  Tf  co o  4303 |  LO  CM  CM  15291  CO  o o o co  j  h-  O)  35351  rf  45821  oo  5690  Appendix F. Leachate Characteristics Data  272  o oOo  co  in  CMo to  TT  Ti-  ooo  |90S  0)  8  03  c co o CD o  o o  r-  00 O o  o o co  IV  Tf Tf  Tf  co to oo CMo CM o to to CM |v m Tf Tf  Tf  *"  CMto o O o 8  Tf  Tf  03  Tf  o o o cn  fv  3 co O o CO O o  CMCMo O o too o 8, IO o <o tv cn to o C S! (OO C O CM co 5) t0o3 C CM O o cn to o to o in o o to C CM O 0 ) CM 0) Om cn IO CO o CMto SI C C M in <o Tt  Tf  [ 1020]  Ti-  Tf  O  o  fv  Oo in  oo o co Tt  o  Oo  Tt  Oo  o  o o o o IO  CMo  O  o o  CM  CM|v CMo  co  CM CO O o  o o  OOo  o o o  Tf  co co tv CMCO co  CO O o o o co  CMCO o o o  in  o cn o o o cn  Tf  Tf  co CMsi cn 8 in S! co CMCM CMco O o o o O co CM 0) o o o o cn C CM fv 0 > CO o o O CMoo o o o co Tf  Tf  CM m o  o o o  Oo  o o o  O  o o o o  m tv  ooo  Si  co o o o o co  Oooooo  o  Tf  o o o  Oo  03 CMo o o ccnn tv  tv  CO |v in co o CMO tv m oo |v m co in m mC M cCnM8 co o 0 3 CO CM co co CM CMCMin co oo cn CO in CM CM tv I O t o in in o o o o o o tv in O o CO fv co O o o o co CM tv ) tv tv co in to c o in cn tvCMccno cn co 0 ino in CO |v tv CM cn CM CM CO tv CM co Tt  Tf  Tf  Tf  1—  Tf  IV  cn m o o o  Tf  tv  O oo)  fv  0! in to co in  m  co  I I Total 1/11/95 Acetic Propionic Iso-butyric Butyric Others Total  IV  Tf  tv  1 I I I  co O o o o co  o o o  tv  Acetic Propionic Iso-butyric Butyric Others  o o o  CMo  oo  c co o  OOo  tv  CM  Tf  o o o  O) o o o  o o o  tv  OOo  8oooo8  CMo  co  Tf  in  co CMo o o  CO  CO S!  tv CO o O o CMCM 8 CMC CM O  Oo oo Oo  o o  SI  Tf  Oooooo  CM CO  Tf  o o o o  oooooo  o o o  |V  Tf  CO C CMSi CM O o o 0) tvo CO CO co o CO co IV  CMo  co  Tf Tf  CO  Tf  o o  co  tv cn oo CMm 8 8 in cn CM Tt  Oo  Tf  o o  cn O o O o 0) tv o o o o o in Tt  tv  1/18/95 Acetic Propionic Iso-butyric I Butyric | Others I Total  ooo Tt  12/23/94  |  mc cno o cn in fv CM 00  o  Tt  03 § to Column # 1 VFA Type Date  O  co in tv CM  D o o tv to O) tv o oooC tr-M o C 8 CO to to s C M CM CM o |v in C O o m o to |v co 00 o O O) o C O) CM co CM 1 |v to  loot. |  CM  co o  o o o  to O o o o co  tv  oooo  Tt  CO  Tf T—  tv  i —  o  Tt  J  fv  fv <£>  in  to o o o o to  C 0O 0 co tco oo o  -  co  Leachate Volatile Fatty Acids Distribution (mg/L)  O ^~  |  [  CM  Tt  tv  o  O |v  Tt Tf  CO o  Tf  co o o o O Tt  M 0) 8 CMC C O CM  o o  in  Om Oo  o o o co  O CO rv CO C CM oo in  Ooo o  s  CO 0) CO C O tvCO in CO CM CM cn CO 8 Tt  cn  CO co co cn o tv co oo  tv  tv  O  o  oooo Tf  |v  ccno m  s  2/15/95 Acetic Propionic Iso-butyric Butyric Others Total  fv  0 0 0 8 in CM0 CO co en  CO co o cn otv m co co  Tf Tf  2/1/95 I Acetic Propionic Iso-butyric Butyric Others Total  TT  o  o o o  CO  1/25/95 | Acetic Propionic Iso-butyric Butyric Others Total  27401  C M 0 00 )  co  fv fv  o  3606  m  o o  C CMco too CM O o C M  IO in  o  | 1975  Oo  CM CMo 3374j  tv  o o  37701 20211  10  O  44671 2464]  CO o oto in CM 0) CM  CMo  |  r-  tv  4236  o o o o  23071  03  1587  Appendix F. Leachate Characteristics Data  273  Appendix F. Leachate Characteristics Data  0)  3  in o o o o 10  in  o o o o o o  CO o  00  CM  in Tf  o  s CD 8 CM Tf  o O o O  o o  O  o  O  o  o cn o CO in  Tf  Tf  m  55  m  CM  CO  Tf  oo  o CO  co in m o CM  co o  Tf  CM CM  *-  CM CO  o  O  co  o  Tf  co o o o  T?  o in cn 0) T f o co co CM CM  LO CD  in o o o O m  oo o  Tf  co o o  o o o o r - r-  o  in co co h- co  CM  co o O o O CO  Tf  o  o  00 r«-  Tf  co  ,609  (0  o  O) CD CM  o o CM  5782  o m r- co  o o CM o CO  1449  CM m CO co CM  Tf  3671  I--  o CM  o o  oo  o o CO  h-  CM CM  O  i—  o o cn  8  o  O o  O  o  O  o  Tf  o  O  o  CO  o  CO  f»  f-  Tf  o  o  O  co  Tf  o o  o  o  CD o  o  Tf  CD o  o o o CO  co  fi  Tf  m o o o o ID  o  co  h- o in CM o  in  in in CD CM  Tf  Tf  *-  o co  o  co  co co CD O CM cn CM cn CO ID Tf  CO  CM o  o  Tf  o  O  O  oo  I 1 Others 1 Total  CM CO  I I I  oo CO  O  Propionic Iso-butyric Butyric  1  in  3/1/95 Acetic  CM  o  CO in  Tf  o  CO o  o o  CO co CO CM  Tf  0) o  o o o CO  CM co Tf CM  Tf  *-  co o o o o CO  h. r-. CM CD CO tn CO  10  Tf  CM  o  O  CO CM  O  o  Tf  Tf  o  CD CO  co o O O o co  f- CM lO  o co CM CO o  00  Si  I Propionic Iso-butyric 1 Butyric Others | Total  r~-  3/29/95 I Acetic  m o CO o  I Butyric I Others I Total  oo  o  I Propionic I Iso-butyric  Tf  3/15/95 I Acetic  o o o O  cn  1 Leachate Volatile Fatty Acids Distribution (mg/L) Column* 1 Date VFA Type 1  1  CM  Appendix  co  co O) o CO co o CO T f co Tf CO  LO  f-  o  Tf f-Tf  rco 0) rTf  a 8 ft  rr  Tf Tf  L0  Tf  O  co  Tf  CN  Tf  co  Tf  C\J i—  co rco CO LO  f-  CO  o  Tf  s  o  B!  co  FI  f~ Tf  (0  8  Tf  co  8§  Si  in  CM  3 m CO  CO co  £  in  8 o  co in CO co CO in CM h- CM  co  Bi  CO  cn  2813  3410  1688  7875  oo in o to  co h-  cn co o o CO hLO CM T f CO o  co  oo o CM co  Bi  h- T f cn T f in CO co CO cn o m LO CO oo  O) oo cn 10 LO  Tf  co 00 in r-o CO co  0)  8  5  1  co  o rCM m oo to m  FI  in  CO o co ft o> in LO  CM co Tf co  f-.  to  CO  Tf  Tf  oo oo to CM  co Si Bi o  sl Tf  co  co co co to f - co m CM LO T f co  10  m  oo  Tf  co to  Tf  co  Tf  T—  to  co  $ co  Tf  Tf  O)  00  Tf  *—  co  o  f-  CM in in CO  0) Tf  in  tn  00  Tf  LO LO CO CO co LO CO o o oo o Tf  8  o o CM fCO CO co CO co co LO CO CM h- oo LO hO) in CO O co co co T f 00 co CM Tf  E 3  o  O  f  Co Q  CO o  CO CO  m o co CM  ll  m  co  co in  CO oo O) co CO  10  o h-  Si Si  LO CO cn LO h- 00 ooo  CO CO co CO oo cn oo fSo CM O oo CU O) 0>  8  00  FI  s  m roo h-  CO in Tf  f". 1—  JM O  Tf  CTcn CT CT m  Tf  Tf  to  oo  o  co  Tf f-  co oo CM in  co  Tf  B!  00  Sj  cn m Tf  O) o o Tf co in CM CM  OO  in oo IO oo to CM 00  co oo Tf  LO 00 r-- y— CO cn in 00 00 co o co to co CM LO  s8  LO rco o o> co OO  Tf  fTf  o  co  Tf  Si  Bi  Tf  o CM  o  CO Tf  0)  r-  CM  oo CM  CO hco m m  o CO CO T f T f oo T f in T f in co CO CM CO CM CM co  CO to h- in to co h- f -  Si $  cn co  CO cn m  to  TJ  CM h- co CM CM  h- CO 00 O) CO CM CM  o o co  O) in co Tf co  co co  o> o  fio  CO T f to CO co  LO to T f CM co co co CM CM CM CM tn  co  CT  co  Tf  co  00  m  Tf  o in  in CD  oo co i — oo co in CO  oo  o  o  h-  CTCM  CM  h. o  cn co in  Bi  Si  CM m  to o  to LO to co LO  Tf  LO to CO T f  to  in co co  m  Tf  f--  CM m co o oo oo  Tf  in  00  [•- in m  o  Tf  CO  in c- to T f o cn co LO co oo oo o fCM CM CM CM  Bi Si  CO  oo CO  CT CO cn CM O h. io  CO 00 co CO CO CO  m  in in  oo oo co co  s 1  Bi 00  s  si  cn oo oo in  CO oo oo rco CO CO Tf in 00  oo  CO oo co  CM  Tf  Tf  00  to  h-  CO  CO  8 o  CM  s  CO CO h-  co o  Bi  8 in  FI  oo in  CO co co CM CD co to to T f  Bi  in  m  o  f-  o  r«r-  cn CO  Tf m o CM CO f lO 10 T f oo oo f - .  00  co  10  0) 00  in o fLO CO  o 8 h-m in  co CO CO CO  Tf  Tf  Tf  CO CO CO  Tf  s 1 11 2 8 1 s>  LO  o  CT CT  oo in  f-  oo LO co  Tf  CO Tf  CO  hTf  00  CO CM  o CM LO co CM in  Si ft  co  O)  00  CM co  o co  I Tf  CM 00 h-  12  Tf  hm co  Bi  Tf CO o ft CO CM CM CM  in o CO co co CM  oo CM  Bi  CO in CM  O co OJ  CO o cn  Si Si  FI T—  0)  Tf  CO h-  CO CO tn Tf o o Tf co CM CO CO m tn  oo cn oo o oo co to CT CO CM oo CO CM  o  cn o oo co  1  ft  Tf  Tf  8 co  IO co co CO 10  to  at  CO CM  Si oo oo cn m  ft CO  co co  8  9  po  Tf o CM rto o co Tf  to  in R  in o cn CM  10  Tf  Tf  CO CO CO S! CO  Tf  Tf  Tf  1  Tf  Tf  Tf  Tf  Tf  Tf  CM in co  co  O  8 co  in  oo co  hm co  Tf  co  Bi  oo f» co  Tf  Tf  CO CM  Tf  co co  f-  oo  Bi  00  in  co  CO 00  oo  to T?  |  o o LO o CM CM  in  oo to  f-  Bi  CO  CT Bi CO  CTCtoM T|  Tf  Tf  to  co 00  cCO co  in T f oo oo CM CM T—  CT  Tf  oo o  CO h- oo hTf CM  co  Tf  h- o 00 hCO in  r-. 00 o in CT T f in CO co 00 co o CT r-. LO CM  Tf Tf 92 po go go 9! po CO go S> po m CO O) N. o co oo co C! to CM  m  in  s  OO in CO m »~  o  00  h-  CO  3  CO oo T f CM CM  00  cn  r-  co  1—  Bi  co  a  in m co  cn  CM  N. m cn roo oo CM hTf Tf co  Tf  in CM CO o m to T f 00 Tf co to oo o co cn CM CM CM CM CM co  92 92 92 92  00  in  co o  00  h-  Tf  co T f LO Toof oo co h-  CD  c  f~  CO 00 in to  ~u  E 1- co  CO CM Tf tn  CO 8! co T f cn cn CM T f to in CO 00 h. T f CM  CM T f CT T f CM co OO oo  Bi  Tf  CO o 00 to oo T f I-. oo  CO CO CO cn 1 to in  10  co  FI  CO CO O) o Tf LO T f CO  O r-- CO CO in 00 CM CM LO cn rco to l«- co Tf co cu  h-  Tf  h-  co CO CO O co LO T f CM o o  oo in o co  Tf  ai  o oo  Tf  co o r-. m  Tf  co o  co  co oo  co T f oo o o CT CO CM CM o  CO fCO co h-  co to m CD CO cn CM T f CO  in  f-  co  ft B!  Tf  CO T f Tf CM co  oo in  OO r-- oo co o CO in co  Tf fco o oo CO O co O) T f m C Ol T f CM CO  co  00  LO  f-  f-  B!  fl  Tf  ft 00 R 8! cn co CM o CO co  CO LO m m fco m co 00 00  00  rTf CM OO CO  to CM  CO CO to  0)  i —  3  Tf  Si  Tf  CO oo oo Tf in f>co co  fCM 00 co 10 CO o oo CO O) O CO CO CM co T f *— CO LO LO IV CO LO T f  CM  oo  rcn co  CO 00 oo cn T f r- r-  in CO CO CM CM co f~co  Tf  Tf  CO T f oo O) 00 CO oo LO 00 cn 00 oo  cn co oo co  o  in cn oo co  hco m o  in  LO o oo m m hoo CM T f CM  Tf Tf  CM CM cn CO cn o co co r- T f CM co cn cn f - LO T f co  O Tf  S  h. CO LO LO  s-  o CO h. h- in in 00  Bi  8  co po oo CO cn h-  0)  CO o CM co co co m  in  5> s cn cn  roo  LO in rcn LO Tf co co 00 CO  CO r-  fS  to cn fI«LO CM cn  LO T f r- co oo oo h.  CO co cn co CO  in cn in r-.  Tf  o m O) oo LO in  CO co m co o CO  Tf cn CM CO CM co LO 0) T f LO CO co cn co oo CO T f oo CO CO co  co CO in oo in O) CM OO 00  Tf  S>  in  Tf oo cn co o cn CO CO CO CO co  Tf  CO cn CM o o  00  h-  00  00  CM CM  Tf  co  i o  8  LO CM T f O) cn O) co fR co  co cn rco  CO  O) T f o LO CO P: in Tf 00 CM  a1  00  Tf  cu  oo  SJ  00  8726  3  Tf  3  8  co  m  Tf  CO  in oo CO T ? co  00  Tf  CO co r- o r-. in oo CO ft CM co T f in  oo h. o CO co IO CM o CM Tf CO CM CO o Tf oo C O co CM CM LO 00 co CO f". Tf  h- T f co co o O) co LO r>- co LO T f CU co oo 00 co CM CM T f co O) h- T f  LO  o oo o  co CM LO  Tf  co co oo  CO  CO T f CO oo 0) co LO co  3  Tf Tf CO o CO in oo CM co CO CO in co o M T f CO o co C o CO Tf  CO CO CO CO CM LO T f f» CO CO oo 1— co LO  h-  o  f-  fTCO f CM lO O) CO Tf  Tf  co co r- O LO CM  CO f co h- T f CO rTf  *-  h.  o  4285  00  co  7187  Tf  f-  Tf  co r- oo in cn o> m oo LO m co  7036  Tf  CO co co cu  10430  Tf  co  13298  LO  6796  3  7640  r-  16439  42140  co  Leachate Chemical Coo/gen Deinand (mi  274  Data  Chemical Oxygen Demand 31488  F.4  F. Leachate Characteristics  to oo  00  CO to co Tf  Tf  m cu ft CO co co in  in co  co co  o Tf  o  B! CM to co to co co T f  in o  00  co roo oo Tf  Tf  r-.  f-  co co  LO cn CM CO in  io in  CT 8 g>  CO co O) CM  go in go po go 92 92 in 92 in cn 00 LO in  ^» 1—  2  in  in  CM LO  S  CM  to  m  CM CO  2211 1882  2082  2344  oo CM  co CM  o  Tf  CO CO  co CM  1292  CM CO o oo O) CM  in  co co CM  Tf 0)  oo o co  0)  CM  8/31/94  Tf  CM  Tf  o  rv oo  CM co IO CO in in  o in CO  Tf  3  co co cn co in cn  5 CM cn cn  0)  CM 00  Tf  m  CM cn  in CM Tf  CO  rv cn  4309  co  Tf  5150  co  rv rv CM  o  rv rv  in co CO  CO rv CM  m CO  0) Tf  co co in Tf  rv cn in  Tf  in rv co co rv CM  CO  m Si co CO  Tf  Tf  co  co  Tf  00  in oo rv co CM CO CM  o in o co rv oo co  CO co CM CM  rv CD  rv CM CO o  CM co in co  CM co co co rv  1  rv cn CM  00  00  co co  rv  Tf  2282 2032 1977 2253 2173 2817 3118 3031 4126 3677  1329 1139  4018 4235 4330  cn O) cn CO CM  00  CO in Tf  cn  3660  3459  1097  1500  1875  2505  2650  3060  3096  2684  3375  4690  4570  6720  CM  0)  CM  Tf  CO CM  3 co o CM cn in o> oo  in fv p- i — cn O) in  o  CM co  o>  Tf  co  o  co  m co  Tf  8  rv CM o O) cn  co o cn  CM  co co OJ  rv  oo rv CO  co  CO co  rv O)  o  Tf 01  |  Tf  Tf  o  co co  Tf  m co co  Tf Tf  rv rv  o  CM  cn rv T?  CO rv  in CM  o  Tf  cn co  in in  in CM  cn co in  3/29/95  8  00  rv |v  o  8  3/1/95  CO oo  co  CO  Tf  o  3/15/95  3185  2258  1971  o  CO  2/1/95  1457  3196  2514  2322  00  2/15/95  o  co CM oo co  5287 1124  2122  2384  2218  in  CO co  11/16/94  1363 Tf  4688 1092  2060  1892  2480  3168  CO |v  CO  1012  1349  1893 in rv  3995  o Si  co  CO cn CO  1001 1188  1429  2317  1288  2536 1218  1755  1872  2128  2185  3509  4840  o m CO  00  10/19/94  1535  1959  1920  2640  1724  3  3994 1041  1678  2493  2713  3108  2431  Tf  CO o O)  9/28/94  1556  1930  1026  3134  3457  2579  6160  4910  CM rv m Tf  4582 1767  2503  3758  2796  3070  3316  2646  2573  1545  3492  3869  3036  2617  2745  3964  5730  10530  7210  11780  in in  1428  1825  2487  3570  in <° CO  Tf  1435  2431  2632  0)  8/10/94  2098  2345  m Si  1375  2407  1899  2871  3788  1286  2006  3826  3802  3012  CM CO  7/27/94  2088  2376  2724  2483  2942  3805  1223  1991  3477  3330  2926  00  6/8/94  2266  2913  2330  2340  2341  3244  1873  4713  4118  3569  o  1996 CO CO  1959  rv  2459  3046  2232  3527  2693  3504  3799  3489  6570  5760  4890  6350  12920  11900  CO o CO CM  00  2030  2098  m  2350  o  co  2046  3585  1913  3022  CO O) cn  1612  3872  2008  2924  1735  2106  4303  2056  2070  1944  4265  2214  3120  2460  2175  3066  2547  2295  o co o Si  2824  2151  1912  2111  2304  2277  7190  CD CO  9980  11000  6120  rv CM rv  10890  00 00  9160  12580  14460  CM rv O)  11720  13900  in  6/29/94  2363  1269 CO |v Si co rv co  2006  1424  2330  1912  2133  oo in rv T f m CO  2028  m  co rv  5/25/94  2691  2169  2404  2298  4562  2507  CD  3100  3022  2097  2861  3693  3968  3835  4821  6480  7590  9430  13670  o CO  5/4/94  2814  2453  2604  3446  3982  5030  5970  9350  4242  3000  2302  3292  4490  5400  9340  CM co CO CM  2982  2554  2190  3192  3561  4560  5340  7290  3545  3138  3248  4250  6020  7360  13250  2503  4820  5040  CM co m cn  2890  6030  6830  co CM  4/20/94  2636  2419  2617  2621  2534  3438  5080  7900  9190  o rv  9560  rv  4/6/94  3172  2983  2828  2640  3562  5080  6450  8350  13570  rv 0)  3/23/94  3300  3112i  3  Tf  3/9/94  2/9/94  2992  3026  o rv  3881  3919  5620  5800  to in  0)  2/23/94  1/26/94  1/12/94;  12/29/93  12/15/93  Tf  12/1/93  o 6380  8320  co  6930  rv  6900  14500  co  13660  o>  12140  o  7900  in 14820  ^  7540  Tf  13200  CM  11/17/93  co  13890  CO  10/20/93  CM  12540  Tf  10300  (day)  in  10/6/93  CO  CO m rv  605  Time  rv  0909  Date  CO  0669  Column* 1  F.5  Leachate Total Organic Carbon (mg/L)  Appendix F. Leachate Characteristics Data 275  Total Organic Carbon  CO o CM cn rv CM |v CM co co CM  m m  CM  00  o CM  CM m CM Tf  o  rv rv  in  CO cn co oo  m in rv  CM  CO  Si co  in  *~  Tf  rv co rv in CM  cn rv  o CO in  Tf  Tf  co  co CM  rv  rv Si co  fv  in  Tf  in CO  0)  in  Tf  CO CO  co  Tf  Tf  fv  Appendix F. Leachate Characteristics Data  Inorganic Carbon  1  o  o  o CO 0> co  o o oo T f  o  o  co iv  CO  o o oo T f  o  o  in  o o oo T f  o  o  o oo  oo  o co  Tf  CO in co m  s  o  o  CM co rv rv  Tf  00 o CM o co  co  o  CM o rv Tf  00 co  o  ^  o  o  o  o  o  o  o  o  Tf  o  o  0)  o o o Tf CM  o  o  00  o o oo T f  o  o  rv  o o oo T f  o  o  o o o o Tf CM •r-  o  o  o  o  Tf  CM  1o  o  Tf  Tf  CM o  CM  Tf  o  I  o  Tf  Tf  o  Tf  o  o  o rv  Tf  CO tv  Tf Tf  oo m  o  co  in  8  O) rv co CM  00 o o  in  0) m  o co  CM o  o  in  CO in co co  5  fv oo CJ) CO o 0) co CO 00  |v CM o O co 10 O) CM CM CM  m  81  oo  Tf  Tf  co  m  oo CM  Tf Tf  00 IV rv O) oo CM CO co tv CM tv  3  co m oo T f  in  CD o oo co CO CM in i—  CO CM CD rv  8  o o  co co CM T f  oo m Iv  Tf  CJ) 3 % in  in fv  CO CM fv  m 3 fe co  O rv  oo CM CO CM 0)  o  in  o co  CO m 0)  in  m rv  00 oo rv  in  0) rv tv oo CM in CM o> O 0) T f  CO o o o oo T f  B! oo  8  co co  fv  co  o co  CD co T f CO CD m CO oo fv CM CO CD 00 CM CM  3  o m  CD 00 o CM m fv CM  8  o  in  Tf  fe |v CinO  Tf Tf  tv rv  fv  81  O) co T f co co co CM CM co co IO  IV co  3  rv  81  CO 0)  in  co CO co CO CM in in CM  co co  81  CO  in  CO fv  CM  co  CD 00 rv o o CO 0) 00 o oo o 0) CM CO CM CM co  Tf  Tf  co  m CO  Tf  co CM co  81  oo 0) CO tv o CJ) fv 0) CM CM CM co  co m  O co CM  CO  oo GO  CD CO CD T f T f co O oo Tf CD |v CO in co T f oo co CM CM CM CM CM CM CM  CM tv  Tf  CO o CM CO CJ) 00 co O o CM CM CM  81  co T f CM co co CM CM CM  in in  §!  CJ) o  m CO o co CM CM CM CM  m  co co CO CM oo CM CO CD GO in o in 00 m in m 0) m CM CO CM CM CM CM  Tf  Tf  Tf  Si co  0) tv 00  rv o oo o CM  co  o  CM  in  CO  rv CM fv co co CM oo m T f  o rv  CM  co CO CO CM oo CM CJ)  oo 0)  in  o  Tf  co co  rv  Tf  3  m  |v  rv  Tf  oo CD  co  o rv  m  Si o tv 0) CM  CM  Tf  o m  CO Si co  in  3  CM  00 tv oo fv  tv  Tf  fe CM  3  *~  Tf  o co CM iv  00 tv  0) T f co IV  CM co  Tf  o co  co  co co  Tf  CM  CO co oo tv o m co T f in o  Tf  Tf  tv  00 fv  Tf  CO  3 3 CinO  o co  co CM o  CM o  3 in  co m o oo oo m  co co  co  Tf  Tf  i—  CM CJ) oo oo in  Tf  co m co CM CM  Tf Tf  CD  co co co T f rv 0) m oo oo  o  0) o  CM m 00 CO  1 3  co rv  co CO  co CM oo m fv 0) 0) 0) m o  oo CD co CO co |v  CO T f CO rv CM CM  3  CJ) oo  Tf  rv o oo co  00 CO rv  co o> rv fv CM  §  rv  oo  oo 00 10 o CM CM co co  88S 3  00 O co CM CM  in  CD 0) CM CJ) CO 0) CM rv co CD T f CO in m  s oin  9  1  co  00 in rv 00 CO tv 00 co O) CM co O  CM CO o CM CM  co 00 CO CM rv  3  in oo in in  *-  o co oo co  |v o CO  CM oo  O CM  Tf  co  00 CO  CM  a  R  Tf  in  o Tf CO rv  Tf Tf  00 oo in rv CO  in  Tf  in  CM CM o  CM  oo rv co m T f CO CM  CM  o o o o  co  rv oo oo CM  o  o  o o oo T f  o  co co  o o oo T f  in  O  oo 0> co |v T f CM  CM  CD  IO m o rv CM  CM Si co Tf  o  Tf  in  co co CO CM Si co CJ) CJ) m  o o CD T f  CM  Tf  co CM  co  CM  Leachate Inorganic Carbon (mg/L)  F.6  276  Tf  Tf co in oo o CM Iv" fv co CO CM CM  CD oo CO o m co m CM CM CM CO CM CM  8  CJ) 0)  O CJ) CO Si 0) CJ> CM CM Tf  Tf  u  in Tf  CM  tv oo co CM  8  oo co  fe  T?  CM CJ) co fv CD GO CJ) Tf T? Tf  5  fv  CM  |v CO O 0) oo CO CM CM CM  oo 0) o oo CM O o co fv 0) o CM CM  oo O) tv m Si co CO  CO  Tf  co Tf  CM  in  Tf  co CM  8 co  |v co 00 0)  IO 0) CM CO IO  in  CD  E  % C  E  3 o o  I-  1 Co  o  co  co co co co 9 2 9! 9 ! g> ? cn g> 1 9 co co  CD o  tv  o  Tf  IO  0)  2  Tf  Tf  co  0)  §  CM co  9! 9? i Tf  CO CM CO  Tf  Tf  Tf  Tf  CM  1 in  Tf  Tf  Tf  ? ss  m  CM m  co  Tf  Tf  9! s 92 Tf  Tf  Tf  Tf  in in in in in IO in 9 2 9 ! ? 92 92 S 9 oo CD in 92 m 0) 5 CM 53 CO co Tf  Tf 0) CD o oo CD CM CD co Si tv '— co CM 00 00 CJ) o fv  Appendix F. Leachate Characteristics Data  1300  1220  1940  1820  2180  2040  2560  3560  o  CD 0)  in CD 00  o o o o o o o o o in o o o o o m oo co CD oo co co T f T f CO CO CD co co in in LO T t T f SI  Tf  tv  m o CO m in o m o o o o o o OCO m OO o CO CO CO CD o o CD CD in cn o o in o co o o co co co co rv 0) cn co 5 > 00 m o oo o i CD 0) CM CM 8 co CM 00 3 8 co co o in in in o o o o o m o o o o o o o o o o o o co o o o o cn o o o 0) co o cn oo o o 0) oo CVI oo o CO o o o |v co co co | o o rv 00 o co co co m CO I CM CM CM CM CM CM LO CO fv CVI 00 iono CO CVI CM co o m iin o o O o o o o o o o o o o o tv co n o m CO o o o CO 8 o co o CO co in in in oo CO oo to i n CM co § co CM to rv (0 <o CVI cvi rv c v i o in m O o O o o o o 3 m o o o 8 8 O in m 8 8 8 in in o o 8 co m co o o o o o o o tvo oo CM to CM CO CM CM co CM CO CM o CVI CO CM CVI O) 81 o co m o o O O in o O o o o O o o cn o oo o o o o co CM co in in CM in o o o o co o co rv co o CM o co o o o co LO o oo CD CM CM CO CM CO CM 3 co CM CD 0) co co 3 3 CM CO O o Ofv o m o o in o o ovi OCO o O o o co co co o co in m o o CM o o co o o c o in in co CO oo 8 8 o 8 m o o CO i n (0 CM CM CO CM CO |v CO 0) cn CO oo 8 CM 3 ! m O o O o m o o in o o o O o o o cvi O O o cn in co co (O o o o ft!co o o CD cn co m co oo o> o co CM i0)n CVI in o o OO s o o CM CM CO CD CM CD to 00 CO CM CM CM CM tv LO CM s co CM o CM rv CO o o o in O o m o O o O o o o o CM 00 CO o co oo o co o in o cn o co o o oo o o o o o o CM co rv CM CVI o CO 00 00 CM CM 0) CO co CD 0) CO 8 cn CVI O o o o O o in o O O o o o o o o o o o o o o m in o cn m oo fv o o cn CO o o in o 00 o co ion o o co o o o in to fv r^ tv oo CO CD co m tv 00 o § CO CD CM CM 3 8 CD fv O) 3 CM cvi 8 o CM O o m o m o o o o in o O o o o o m m o CO in o co 8 cn cn rv o oo 0) m o o o o 00 O 8 co s co co co co cn 00 tv C^ co oo rv CO c n I 8 rv 8 8 8 15 8 3 tvCM o oo co CVI 3 co CM CM CVI CM o o o o o o o o o o in O O oo o o o co o o co o |v o CM m m o 00 CD o co o oo o o o i n i n o co to CO in cvi o (0 I n CD 5 > 00 cn o CO CVI 0) CM 13 rv 8 3 8 3 3 3 CM cvi o o o o ion o in in to o o o o o o o o o O o o rv tn cn cn o o o oco o cvi ocn rv o in o co rv co CD o cn IO co o co o o to o 0) in cn o CO tv 1 in o co s 8 3 tv 0) 3 8 co o o O i n i n in o o O o o o o o o o O o o CO tv oo o o o o cn co 0) co co oo m oo co co o o o o o o co co cn cn in oo in o in BJ co co in o CM o o CO fv tv fv fv co i0)n cn 00 CO CM 8 1 o o cn cn o o o o o m o o o o o o o o O ooo in itnn o o co m in co co oo o o o o cn in o o o (0 o co co CM |v co to cn co o cn o o CVI 0) m to CM fv fv CO CM CO CO CD 00 CM 8 CM 1 CM CVI 8 CM to CM o m icon o m o o O O o o m o O o LO o O O o o O o o oo ft!in co o to CM co oo co cn co o CD o (0 o 8! o o co O oo o o CM o i n co o CM o CM o CO co CM CM CM 00 CD CVI CD fv tv co CM oo CM CD s CO CM 8 cvi 8 5 O o O o o o o O O o o O o o o o o O o rv o o o 0 cn co o oo CO CM oo O co o O in o o in in iOCOn o tv CO to co cn 01 to CO co cvi o> LO 3 tv co i n O IO 00 CO 3 CO 8 tv 3 CO CO CM CM CO 3 |v CM i n o o o o o o o o O o o o o O O o iCOn Ocn oo o m in in o in o o co o o co CO o o o CO 00 o o Oo o o O00 o to o o tv CM cn o oo CO 8 1 00 CM CM CM CO CM o 3 8 CM 81 3 rv oo CD tv 00 co co CM cn co co rv oo CM co O o cvi co o co ft! co co o in co CD co o ft! m o CO CO cn in co tv 00 CM m CO CD CM |v 00 LO CM co co co rv o o o cvi o  tv  2760  8440  co  7520  Alkalinity  CVI  cn  T?  Tf  Tf  T?  Tf  Tf  Tf  Tf  Tf  CO  Tf  Tf  LO  Tf  Tf Tf  T? Tf  Tf  Tf  Ti-  Tf  Tf  Tf  Tt  Tf  Tt  T? Tf  Tt  Tf  Tf  Tf  Tf  in  m cn  00  o o o  in o m co  o Tf Tf  o in co to  Tf  1  Tf  CO  Tf  CVI  Tt  Tf  Tf  Tt  Tf  Tf  Tf  Tf  in o CD  CM  o in Tf  in o co in  Tt  o  Tf  Tf  Tf  Tf  Tf  Tf  O)  Tf  co  T  Tf  Tt  Tt  f-  Tf  Tf T  CO  -  Tf IV  Tf  Tf  Tf  Tf  Tf  T?  Tt  LO  Tf  Tf  Tf  CO  Tf Tt  Tf  Tf  Tf  Tt  Tf  Tt  Tf  Tt  Tf  Tf  cvi  Tf  Tf Tf  Tf  Tf  Tf  3  o fi O Q  Tt  Tf  Tf  Tf  Tf  Tt  co co co co 00 co > a> CD 9 9> CD rv co 0 — LO cn o  §  Tf  Tt  Tf  1  Tf  co  Tf  Tf  CD CO CM  Tf  co  Tf  9? co CM CO  Tf  Tt  Tt  Tt  s?  S» CD  CO  9 o? o  CM  CO  Tf  o Tf  in  Tf  Tf Tf  Tf  Tf  Tt  in in i9in n>  —.  §  CO  CM  1  Tf  Tf  T  Tf  Tf  E i-  Tf  Tt  Tf  Tf  XI CD  CM  co in o CM 81 CM  o  CO CM  O CM Tf  m Oco CM CM  o o co  O 00 CM  Tf  Tf  Tf  Tf  Tf  r—  Tf  Tf  iin n  *—  Tf  % c E  Tf  IV  i —  Tt  Leachate Alkalinity (mg CaCO-3/L)  F.7  277  Tf  CD  cn co  Tf  Tt  9! 9! o 00  CO 00  Tf  CO  Tf  9 ? CD 9! cn co co 9? oo  S! —. o 0)  Tf  Tf  CM  Tf  Tf  o 00  O  cn  o o oo oo iton CM  o cn CM  o in iCMn cn in in CO  m in 9> 9!  m 9> in in in in cn 5? CM  55 co  CM  co  Appendix F. Leachate Characteristics Data  Specific Conductance  CO CO  LO CO  W  co co oo m LO od iri T t CM iri  o co co tv co in cri cd  O  o iri  Tf  CM  co co  q cn oo co co d  d  Tt  o o Tf'  CO  T-  i -  Tf'  y- cvi cvi co Tf  Tf  CO  cn CO T f CM cn co cvi cvi cvi cvi  Tf CO 0 0 oo CO co' cvi cvi cvi y~ cvi  00 Tt  Tf Tf  co cn CM oq co' co yco cvi cvi in  tv  fv  co d  Tf  CO  d  d  cn co  fv  d  d  d  co co co co m  LO  Tf  d  d  y- tv  CO  q  d  in  Tt  O  o iri  Tt  o  O CO  od  iri  co  in  cn  CM  cb  iri  Tt  co oo o cn 00 cvi cvi co cvi cvi  00  Tf  Tf  T—  cvi  CM  Tf  fv  oo  CO tv' iri  iv  CM CO  in  co'  o co  tv tv  |v CO  in CO  m T f T - in co fv co co in o cvi cvi cvi cvi cvi cvi cvi cvi cvi cvi  CO Tt  Tt  iri  T—  iri  CM CO  Tt  0)  r-  CM  T- cn iri 00  oo od  Tf  CO iri  o  o fv  co cn  Tf  in CM  Tf  CM  cvi  Tf  0)  CO  y—  T—  y- q  T  -  fv  tv co T - 10 CO CO T f CO y- T f co cvi cvi cvi cvi cvi cvi cvi cvi cvi CM  CO CM  o  Tf  2/9/94  2/23/94  s  CO  co  Si co  CO o at CM  in Tf  CM  CD CO CM  d  co  d  d  co m  in  in  Tf  Tf  Tf  Tf  Tf  d  d  d  d  d  d  d  d  d  co co co  tv  fv  d  d  co co co co  cq  in  d  d  Tf  co  in  d  d  co co oo d  CM  q i —  d  d  oo co  in  in  Tf  Tf  d  d  d  d  in  m  Tf  d  d  tv  co co  d  d  d  d  d  at  co oo  cn  d  d  d  d  d  co  fv  in  d  d  d  q oo  fv  fv  d  d  co  in  d  d  d  CM  at d  m d  cq cq  in  at  co  fv  tv  Tt  in  Tf  Tf  Tt  CO  Tf  d  d  d  d  d  d  d  d  d  d  d  q  rv  CO  in  Tf  Tf  Tf  Tf  d  d  d  d  d  d  d  at tv  tv  d  d  co co m  in  d  m  o  IT) iq  CO  q cn co co oo  at tv  d  d  co  d  at  y—y^  d  d  co  d  q q q q q  tv  1/26/94  1/12/94  12/15/93  11/17/93  10/20/93  tv CM  oo tv oo T f co co oq co cvi cvi cvi cvi cvi  Time (d  Tt  Tt  Tf  d  d  cvi cvi cvi cvi  U) CO CO T t  cvi cvi  LO  d  d  o cq cq CO fv CD in in cn o cp y- at cq cq in cvi cvi T— cvi cvi cvi cvi cvi cvi i— cvi i — y—y-^ CM CM  d  d  CM  co co CM co cvi cvi  Tf  d  d  d  q q cn q q q  in  d  co  T-  d  d  d  d  d  in  in  Tf  CO  CO  CO  CO  d  d  d  d  d  d  d  d  d  d  d  00  CD  CO  CM  cn  in CM  cn co  3/29/95  14.2  LO CO  IO  y—co  Tf  d  CM  d  d  d  tv  Tf  oq  Tf  co co co co co co co co  cn tv co co cvi cvi cvi cvi cvi  Tt  co  d  d  CM  tv tv  O)  d  Tf  cn CM oq cvi cvi  Tf'  d  d  CM  o  d  Tf  co tv CM cn co co cvi co co  Tf'  CM  d  CO  d  CM  cvi  co  Tf  Tf  d  d  d  1-  cvi  d  CM  d  o  tv  d  co co co co co co  Tf  y|v iri  Tt  o tv in co cvi cvi  d  tv  Tt  d  Tf  co q  Tt  Tf  d  d  Tf m m o o o CO CM o cvi cvi cvi cvi cvi co' CO cvi cvi cvi  CO  Tf  d  in CO  d  Tf  CO  Tt  Tf  Tf  d  d  d  fv  d  Tf  Tf  d  Tf  fv  co oo m T f o cvi cvi cvi cvi cvi  co  co  Tf  d  q  d  d  Tf  Tf  in  iri  m co  CO  d  oo CO  Tf  CO CO  in  10/6/93  d  cn  LO  o  d  in tv  Tt  co  Date  d  d  3/15/95  8  CO  d  § Si m tv o co CO co T f CO  8/10/94  CM  co co  6/8/94  CO  CO  6/29/94  Tt  Tf  d  0) Tf  LO iri  IV  LO  d  o iri  17.0  LT)  Tf  d  cn at T f o co cq oo d co co co co cvi  oo  OS  CO  in  at  y- CO tv iri  cb co  tv  CM  d  cn co co fv T— m |v cvi cvi cvi co co co  5/4/94  00  Leachate Specific Comductan  od  y-  0>  E co E.  in CO  cq  d  Tf LO cn o *- o o cn o co cn co Tf Tf Tf' co CM cvi y~ cvi cvi cvi cvi y~ co co  y- CO CO  CO  d  10/19/94  co  oo  tv  CM  d  9/28/94  tv  CM  tn  Tt  CM CM  CM  d  8/31/94  10  CM tv  co tv co' cvi  CM CM  CM  d  d  co Tf  CO Tf  tv  CO tv  cn in m  Tf  in  Tf  3/1/95  Ot  Tt  CM CO  CM  d  d  2/1/95  CO  Tt  co'  CO  d  d  2/15/95  CO  Tt  Tt  CO  d  1/25/95  r|v' CO y-  Tt  Tt  iri  cn co oo oo co co  1/18/95  |v  00  CM  1/11/95  Tt  in  12/23/94  co cn o  Tt  4/20/94  co  Tt  4/6/94  IT)  o oo co |v y- cn oq cq CO c\i cvi cvi Tt  3/9/94  (O  Tt  3/23/94  iv  o>  11/16/94  co co oo Tt cvi cb  CO  i Column #  F.8  278  o  Tf  CM  6024  5112  4524  CO  CM  o  3  3860  3338  m  CM  Tf  6/8/94  4042  4174  o  5/4/94  4/20/94  4/6/94  4154  oo CM CO co 00 CO  3/23/94  Tf  3/9/94  2/23/94  6140  CO  2/9/94  h-  1/26/94  CM  in  2052  1698  1394  1232  1164  co  CO CM  co o co  oo  CM CO  in co  co hco  Tf  8/10/94  8/31/94  9/28/94  10/19/94  11/16/94  CM  3116  1250 1010  1366 1034  Tf  co cn  Tf  oo  co  co cn  o 1180  o  Tf  1354  4267 co co  o 00  co T f oo in  Tf Tf  CO  o FI Tf  cn co  CM CO  oo co oo  3  o oo co rft!00 f - .  o Si co o o o o oo co oo f - . f o o  Tf  Si  o  CD CD  o  CM  CD CO  CD CM CD  3 co tn  co o  CO  o  3500  o o Tf f-. Tf 00  CO in oo oo rv cn co  CO  oo  oo 00 oo oo  CO  Tf Tf  Tf  8  CO  CO  CO  r-  s o CO  CM  f-  00  Tf  1  o  co T f oo 00 co in  3  h- CO 00 oo CO  CM  co  Tf  o Tf h- in  o in  oo CM co o CO  CO  CO  m CM  h-  5)  cn  in co  o  3  Tf  8  3100  CM  3200  Tf  CM CM  SI  2246 1242  00 00  CM CO  3300  CO  CM  3982  o oo in co CO CO CO  o  CO CO CM  i to  CM  CO CO O  o 00  Tf  CO  CO CO  CO 00  CJ!  CO CM  CM  CM  CO 00  o  o  o  in h-  o  o  oo co co h.  Tf  3400  4517 CO  3618  5240 CO  4074  6078  1216  CM  00  CM  CM O  cn  o  CM CO  co  Tf  o  s3 00  Tf 00  co  ft!  CO  o o oo in T f  oo o co CO  o  h- CM m in  Tf  Tf  s  00  CO  o  co  CM CD CO CD  CM  CO CO  co co  ft) cn CD  co  r-  00  oo co co co Tf  cn  Tf  Tf  CO  f-  Tf  Tf  co oo in in in  o  in  in  CO  3  Si  o o o  Tf  CM  3  Tf  CO  o  m  Tf  3  h-  h.  m  in co  Tf  Tf  tv  Tf  Tf Tf  to co  in  in cn CM CO in m  O  3/29/95  1594  2086  5220  1294 5490  6472  2030  2454 4932  2868 4078 4360  3410 3740  CM  1242  in  o co oo f -  3/1/95  2172  2182  Tf Tf  1395  6040 co co oo co co co Tf  1272  6402  6342  1758  1742  m co co oo oo r-- ID  1464  6040  1400 co Si co oo 0 0  1526  co fin  1446  5374 o o m Tf r- co  Tf  3/15/95  2262  2508  1108  6182 6286  4636  1106  Cj  1766  2294  1292  1566  3960  2012  2466  1308  co Tf Tf  co  2/1/95  2728  3002  3320  3436  1330  3430  2090  2862  1472  1980  Tf Tf  r- r»  1/25/95  3362 2758  3572  5198  2014  1286  3078  2562  3348  1996  3300  4096  4990  o oo  1/18/95  3750  4210  3852  1754  2444  2688  3412  3954  2152  2660  3834  3368  3498  2546  4046  2856  3356  4684  5632  2786  4564  5372  5792  6446  7146  7902  co co  1776  1736  3504 2408  1014  3832  4636  2836  4242  2356  3090  3558  4118  5094  3242  3718  6098  4616  4976  6256  8270  5072  6426  3916  6562  3990  5946  5416  8476  5774  5782  7396  7192  7166  9772  CM CO  1932  3984  4608  3016  5112  4884  4280  4802  6454  6972  7546  6230  9036  9884  o  2214  5856  1002  3994  4544  4022  2988  3726  5470  6370  7636  7858  7388  8526  CO CM  IO  1022  6504  1162  4430  5062  5850  3558  4046  4580  5068  8336  9726  11492  cn co  1/11/95  3218  6866  1466  4054  4948  4062  4304  5482  9254  9932  co oo  2788  7232  2098  3680  4606  3834  i  4436  7890  CM  1068  3878  7062  2404  2826  3842  3752  m  5812  CO  6350  CM O  4394  3044  3620  4000  3 co CM  CO  5278  3634  4092  4424  6048  4738  4982  6206  6568  5462  7340  5206  8176  7340  7634  7646  9538  Tf  6800  7762  co  o>  8326  oo co co  O)  1096  1480  3914  4300  4230  4276  4260  4446  4822  5304  5354  6818  8278  9682  Tf  in oo  6/29/94  2004  2684  2964  3474  3860  4582  5060  5168  5654  7524  8936  12700  28906 25336 29614 31718  7846  Tf  9186  Tf  12/29/93  o  12/15/93  co  11238  in  14014  CD  11934  r-  16780  00  12/1/93  CD  11/17/93  o  37824 33006 35220 40496 36548 35014 35738 36126 33752 38512 28298 33588 31992 32952 33278 30220 28770 25052 36182 34460 33512 37704 33234 37344 28912 27470 33068 25064 13298 15816 15212 13440 12018 13698 13978 18196 14594 14870 16114 12838 12220 16682 12112 9628 10648 9442 9788 9496 9678 10280 13710 10546 12062 11868 12098 10430 12124 10516  Tf  34604 36036  CM Tf  90S  CM  28464 32618  00  10/20/93  Tf  o cn  0691  (day)  ID  10/6/93  co  9099  Time  h-  9999  Date  00  0009  Column #  F.9  0969  Leachate Total Solids (mg/L)  Appendix F. Leachate Characteristics Data  279  Total Solids  Tf  CM  SI  3 CM  Tf  CM  CM CO  co  CM CD  Tf  Tf  tn  o  o oo m  CO CM  co  Tf  Tf  O  co  Tf  co  Leachate TKN (mg/L)  Tf  co  CM  co CM  3  co CO  Si oo  co CO  o  CM  10 Tf  co co  Tf  CM  CM  o 12.3 11.9  O) CM  15.1  LO CO od  22.1  15.8 15.3  LO UJ  cri  |v cri  co  UJ cd  co  CM cd  UJ cd  IV  o  CD  cri  oo CD CM CO  |v  00  10  co  13.3  tri  tv  rco  56.9 15.1  21.1 to  17.7 47.4  83.9 119.7  CD  77.8  79.0  126.9  CD  Tf Tf  od  CM  Tf  CD CO  00  tri  00  CM cd  Tf  *—  cd  Tf  O)  O Iv  od  CD rv  to  tri  Tf  O)  cri  cri  uj  cvi CO  14.3  6  13.5  Tf  15.8  19.7  27.7  42.9  38.5  41.0|  48.9  59.3  84 0|  81.7  169.7  192.0  386.1  255.5  14.7  46.0 co  co tri CM cvi  10.9  co  15.1  12.2  Tf  12.1  co  22.5  UJ Iv cvi CO  17.2  93.2 98.9  76.1  80.4  10.8  LO co  22.5  93.8 94.8 CD in cri CO  18.9  85.4  to  CM  00  CO od  to  co CM o co  CD  co  co  Tf  T?  IV  Tf  3  UJ  2/1/95  16.7  10.1  53.0 78.1  73.8 14.3  cvi CO  1/25/951  15.8  13.4  18.8  57.2  74.1  65.1 10.3  15.8  61.0  125.0 |v  28.7  47.2 11.0  io'  10.5  24.4  62.8  43.2  45.0  53.8  CO Tf  29.8  18.8  27.9  49.7  33.6  93.9  CM  Tf  CM  co'  1/18/95  21.9  17.7  22.4  26.1  10.1  21.0  27.0  12.4  11.6  45.5  29.3  114.2  66.7  74.8  68.0  CD co CO cvi co" cvi  12.1  16.7  16.5  26.3  17.2  34.9  27.6  141.7  91.0  93.6  123.7  245.0  Tf  13.2  17.1  14.1  23.6  33.9  6  25.4  16.6 16.4  27.9  43.5  o  14.0  17.4  10.4  14.2  to'  30.2  19.3  17.5  36.4  42.1  CD  35.3  19.5  15.7 20.0  42.8  37.5  47.0  194.5  134.8  22.9  CM id  11.7  31.2  21.5  15.6  17.2  20.7  57.3  21.0  36.2  51.4  254.7  182.9  28.2  CO CD cri cvi | v  15.2  32.0  23.4  23.8  23.0  20.0  57.1  17.3  34.9  32.4  00  CM  CO  Tf  to  co co Tf  CO  Tf  CD  o  tv |v  Iv CM co' tri  oo  Tf  |v  CM  tri  iv  1  2/15/95  33.1  40.2  17.3  28.0  16.0  54.4  27.5  48.4  26.8  25.5  117.3  398.9  314.0  335.5  od  38.6  28.4  16.2  12.3  29.6  10.5  47.9  33.8  60.5  41.1  63.0  97.5  161.0  508.7  438.6  o>  15.6  16.6  co CM  28.5  20.1  21.4  33.9  15.7  51.0  37.4  49.1  oo IO  10.7  46.5  17.0 23.1  18.7  21.6  36.2  15.5  O O)  16.3  43.0  30.2  17.7  25.9  38.2  18.2  90.4  91.0  47.6  84.3  O) CO  33.2  26.7  50.0  32.8  20.5  20.7  38.0  34.7  98.4  135.5  69.9  130.0  CO LO  16.9  12.5  31.2  46.0  40.8  20.6  33.4  54.2  49.0  75.4  146.2  213.5  278.2  CM  o>  CM LO CO  Tf  11/16/94  o  LO cri  0> Tf  10/19/94  CO LO CO  to  17.6  16.5  32.3  38.9  39.8  28.3  88.1  62.7  176.1  187.1  283.4  to'  o  LO  9/28/94  22.6  25.2  31.2  30.4  49.7  28.5  36.5  105.5  177.6  247.8  280.8  379.6  565.6  359.2  509.7  255.0  847.8  826.1 1079.8  468.0  Tf  8/31/94  22.4  43.3  40.6  47.5  to co  55.6  199.8  199.8  560.3  404.4  co  00  oo od od  8/10/94  22.4  62.2  30.8  68.8  oo |v  54.0  89.7  UJ  50.4  272.6  |v cd  228.9  cri IV  Tf  7/27/94  23.4  35.4  53.9  64.0  48.4  93.4  125.3  226.0  200.0  641.8  720.9  co o co cri cri T f  |v  Tf  6/29/94  30.0  83.9  102.7  77.4  114.4  100.6  144.3  254.0  CM  66.2  146.1  165.9  256.6  362.7  650.1  666.9  CM  15.6  30.2  86.1  98.5  121.4  245.1  354.7  438.5  401.2 1035.2  385.9  CM co r-' | v  6/8/94  30.1  131.9  124.5  177.8  305.7  331.0  621.3  456.8  CM |v  5/25/94  59.6  168.4  200.0  317.4  471.5  789.8  964.2  o o>  5/4/94  4/20/94  4/6/94  3/23/94  3/9/94  2/9/94  89.0  CM  o>  26/1/94  130.1  Tf  co  12/1/94  29/12/93  15/12/93  237.2  o  Tf  1/12/93  CM  625.0  437.1  (O  958.5  f-  395.7  LO  874.8  co  574.9  co  351.5  Tf  521.2  o  877.8 1122.8  CM  17/11/93  co  824.5 1013.0  CO  702.5  Tf  614.7  LO  20/10/93  (day)  <o  6/10/93  Time  ro  00 00  CO Tf  CM CD CO  tri Tf  tri CO CO  Tf  CM  od |v  OJ T f CO cri  Tf  |v  09  Date  co  909  Column # 1  Appendix F. Leachate Characteristics Data 280  F.10 T K N co UJ  Tf  Tf  |v  to'  CO d  o> 0 0 CO tri cri cri  cd  |vi  iri  co  od  Tf  iri  |v CD  Tf  32.1 15.5  11.1 10.1  25.2  Tf  Tt  co Tf  CO 0)  1  15.1  22.3  40.3  75.3  133.7  209.3 151.2 103.3 63.5  86.4 48.6 24.0  202.9 135.5  151.2  142.5  17.5 11.5 23.7  41.0 42.6 40.7 46.4  10.6  CO  (v  co co  rv  Tf  CM rv CO  0)  CO  Tf'  m co co Tf cn  Tf  CM CO  CO rv  co co rv'  in m iri r v CO Tt  CM in co cd iri iri in  co  m o>  CM  Tf  O)  co d d  iri co iri cvi  rv  m q co O ) CD d d d CM  co cvi d  co CO d d  cvi d d O)  CM Tf'  CM Tt  Tf  O)  CO  o CM co cvi cvi  CO  o o CO co'  in o  CM  o d q  co 00  CO  CO  co  Tf  22.3  30.3 14.2  40.0  43.4 57.9  37.4  32.2  45.0  56.8  CM  co d  61.0  52.3  26.3  17.1  19.5  60.0  29.3  28.3  53.5  63.5  24.0  89.1  53.5  77.9  107.2  152.4  247.3  53.7  95.6  206.4  144.6  272.8  289.4  459.2 291.0  272.5  145.0 244.9  417.5  206.4  290.3  392.9  242.5  10.7  34.0  83.3  138.6  190.5  326.5  231.3  cq oo d  Tf'  CO Tf  co o 00 cvi cvi d  0> CO  CO CO  12.3  41.6  co  rv rv  o  12.5  fv  rv  11.4  90.9  48.0  42.2  co CM  16.9  11.5  tv  10.2  140.6  81.7  74.1  CO  15.4  14.7  11.5  28.6  194.7  133.2  114.7  CM CO  CO CM  in  11/16/94  10.8  32.0  15.2  24.9 26.3  28.2  11.2  39.1  CO  21.2  46.9  12.3  29.4  O)  69.0  239.5  192.8  172.5  cd iri rv Tf  CO  9/28/94  CO  co cvi co  d d  CO  10/19/94  o co cvi  o o o d d d d d  cvi  8/31/94  13.7  16.4  28.9  31.4  72.8  26.8  57.4  rv  115.3  74.0  81.4  CM  104.4  156.1  123.3  119.6  183.6  231.1  180.6  255.8  185.1  254.0  0>  144.5  179.6  219.4  356.2  335.0  Tt  d  8/10/94  12.7  47.4  71.4  116.6  162.9  237.0  co  384.1  304.1  243.0  360.0  227.5  222.5  CO Tf  rv  7/27/94  Tt rv'  6/8/94  22.6  45.2 CO  13.7  52.1  61.8  90.4  144.8  rv  10.5  78.5  122.3  161.9  211.3  316.7  449.4  290.0  421.6  475.0  356.3  252.5  in iri  csi  6/29/94  CM rv  4/20/94  3  22.7  54.9  o rv CM  rv  SO  m  91.7  211.5  272.5  405.0  372.5  rv  CO  3/23/94  CO  2/23/94  CM Tt  26/1/94  Tt  29/12/93  150.2  o  15/12/93  231.0  i  1/12/93  CO  17/11/93  Tt  352.6  m  277.5  co  470.0  tv  421.8  co in  cp  SO  CM  397.2  0) 0)  CM  SO  o iri co  crj  90  ^  334.3  CM  307.5  co  20/10/93  Tf Tt  SO  Time (day)  in  6/10/93  co  Date  CO  SO  Leachate Ammonia Nitrogen (mg/L)  F.ll  90  Column #  Appendix F. Leachate Characteristics Data 281  A m m o n i a Nitrogen CO co CO d d d d  CD  CO  d  m  Tf  iri  GO  in  co cvi  cvi  IO  cn cvi co  Tf  cn  Tf'  co'  co CD t v 00 CO o in v o Tf co si co rco co  0.52  0.80 0.78 0.80 0.76 0.60 0.50  0.52  0.42  0.50  0.34  0.26  0.24  0.30  0.12  0.12  0.08  0.04  0.06  0.04  0.08  0.02  0.00  0.68  0.70  0.70  0.78  0.94  0.92  1.06  0.94  0.96  0.80  0.72  0.68  0.62  0.58  0.47  0.36  LO  to to  Tf  co  oo ro Si 10 co to  oo N. CO  to  LO  to o I'-  co  cn  CM  Tf  to  Si co to o  CM  CM  CM  CO CM  CO  0.10  0.16  0.00  0.10  0.19  0.45  0.23 0.01  0.03 0.00  0.33  0.59 0.01  0.13  0.12  0.21  0.38  0.32  0.68 0.41  0.00  0.04  0.12  0.80 0.14  0.08  0.82 0.29  0.42  0.42  0.08 0.00 0.00  4.40 2.40  0.04  0.02  0.02  9.94  10.14  7.00  6.54  0.08 0.00  0.04 0.01  0.06 2.02  0.06  0.10  0.28  0.14  Tf  11/16/94  0.86  0.28  0.98  0.06  0.06 0.96  0.96  0.02  0.42  0.52  0.78  1.10  1.40  1.96  Si co  10/19/94  0.38  0.16  0.30  0.18  0.74  0.64  0.68  0.48 CO  9/28/94  0.52  0.04  0.40  0.18  1.00  1.10  0.80  0.40  o  0.74  0.74  0.04  0.58  0.26  1.20  CM  1.28  5.74 0.10  0.80  0.36  CD CM  Tf  8/31/94  0.74  0.04  00  0.66  0.06  5.80  0.14  0.38 CM  o>  0.24  1.58  0.04  4.28  0.06 1.00 0.96  0.32  p  1.24  0.82  0.04  2.22  0.16  0.08  0.04  2.361 2.20  2.30  2.001  2.32  2.44  2.40|  2.42  2.40  o Tf o Tf o oq to to t-; h;  8/10/94  CM  7/27/94  Tf  1.40  2.60  0.80 0.96  to Si o> 0.04  Tf  0.02  co  0.24  0.22  2.10  co  6/29/94  0.20  2.10  to  0.82  0.40  2.18  2.88  0.88  3.42  0.26  1.40  oq  0.82  2.18  2.88  0.20  1.36  2.44  0)  6/8/94  0.34  00  CO  0.72  2.02  0.40  2.80  0.88  0.10  2.34  0.06  0.14  0.16  0.40  oo co  5/25/94  CO  5/4/94  $ s 0.40  p  0.66  2.10  0.18  1.74  0.36  0.76  2.90  2.42  2.24  2.24  3.66  2.08 3.14  4.04  CM  2.22  0.58  0.08  0.34  0.60  1.56  0.14  2.06  1.56  0.46  0.36  0.32  0.32  2.08  to o  4/20/94  4/6/94  to o  I  Tf  LO  1.80  1.34  0.41  2.18  0.68  0.86  0.34  2.96  0.18  1.52  0.24  0.88  0.36  0.60  0.76  0.32  o  CO  0.58  to o 1.90  0.92  0.48  1.74 2.80  co  3/23/94  oo CM  Tf  I  Tf  2.44  o  2.66  0.58  1.78  0.36  2.00  ^ 0.66  0.20  0.66  0.24  2.00  0.24  CM  3.14  CM  3/9/94  2.10  0.18  to  1.66  0.56  0.18  2.22  0.32  Tf  2.28  0.24  0.74  0.32  Tf  2/23/94  0.20  2.62  0.27  to  0.56  0.64  2.86  0.28  Tf  0.38  4.06  2.20  0.46  0.22  0.86  0.32  0.00  0.90  0.38  3.26  0.24  Tf  1.60  to  0.38  4.16  0.32  Si  LO  0.38  0.10  10.80  0.80  2.80  Si  0.36  1.20 0.80  21.20 j  0.88  2.00  Tf  1.62  oo  2/9/94  3.78  2.34  0.50  0.88  3.18  2.40  0.38  0.07  2.26  0.53  0.99  0.54  0.06  2.76 2.58  0.36  0.56  0.04  3.16  3.601  3.58  2.50  1.06  0.30  0.24  1.38  0.32  <£.  Tf  I  0.52  0.50  0.60  co  Tf  0.16  0.72  0.28  3.88  1.60  Tf  co  1/26/94  0.34  0.50  0.54  00  2.16  7.20  2.54  f-  0.40  p  1/12/94  0.26  0.39  0.44  Tf 10  0.44  8.38  oo  0.48  to  12/29/93  0.38  0.48  Tf  2.36  5.20 to  CM  ll 2/15/93  0.28  0.44  o Tf (V  0.24  10.14  1.30 Tf  to  12/1/93  0.32  CM  0.80  to  7.60  (0  0.56  Tf  6.30  0)  0.40  O  11/17/93  CO  0.86  CO  1.12  Tf  0.40  LO  1.28  f-  0:80  00  10/20/93  F.12  10/6/93  ID  Date  Time (day)  Leachate Zinc (mg/L)  {Column #  Appendix F. Leachate Characteristics Data 282  Zinc  co oo cq  rto  T?  10/19/94  167.6  113.0 115.2  164.8 140.6 144.6 145.6 136.4 125.4 94.9  212.0 204.6 210.6 199.2 193.6 177.0  70.0 64.2 64.2 61.8  112.0  102.0  101.6  93.6 cd  77.4 80.9  85.6  77.2  147.2  155.4  157.0  99.6  157.6  194.0  72.8  96.8  173.8  82.2  92.4  135.4  161.4  78.8  77.6  100.6  124.2  78.8  65.6  97.4  130.0  84.4  59.6  CO  9/28/94  8/31/94  8/10/94  7/27/94  6/29/94  6/8/94  5/25/94  5/4/94  4/20/94  4/6/94  3/23/94  Tt  154.0  154.8  148.6  145.2  142.4  135.6  109.4  88.0  80.0  96.6  114.6  92.4  55.4  3/9/94  75.4  97.0  118.0  72.2  56.8  rv oo o co in CO 3 8 co co co a § 83 in rv 0) CM CM CM CM CM co co co co  2/23/94  68.6  91.8  100.0  78.8  54.4  CM  2/9/94  70.2  86.0  24.0 24.4  115.8 101.0  116.0  22.2  111.4  84.4  126.4  133.0  109.6  71.8  61.0  120.6  67.6  70.8  87.2  123.8  159.2 87.1  74.4  74.2  71.6  94.8  104.0  48.8  203.8 195.2  128.6  66.4  215.4  77.8  128.4  224.4  119.6  73.4  64.4  131.0  121.0  68.6  86.0  220.2  120.4  85.6  60.5  53.0 47.7  72.0  64.8  52.4  65.4  62.6  57.2  77.0  87.4  75.0  64.6  62.4  65.2  73.6  68.4  51.4  135.2  138.8  66.2  109.4  93.8  75.6  105.4  200.0  220.8  90.4  94.0  94.6  83.2  87.4  82.1  101.6  125.4  121.6  109.2  26.3  24.6  24.4  25.0  24.4  33.4  31.2  33.4  62.8  77.8  72.0  67.6  36.2  156.1  36.5 273.0  177.0  83.4  281.8  178.4  74.0  97.0  168.6  37.2 165.0 65.4  139.4  78.6  49.2  44.6  30.8  36.6  29.4  32.2 123.2  85.8  30.6  99.4 108.8  87.2  276.2  277.6  268.6  220.8  202.0  172.8  22.4  28.8  29.0  33.6  41.0  44.6  47.0|  43.2J  45.6  44.2  48.61  55.2  94.8  126.8  93.8  79.4  74.6 138.8  70.2  75.0 74.4 105.8  57.0  39.0  87.6  116.2  113.0  171.0  80.8  113.8  45.4 45.6  77.2  60.0 52.2  45.6  42.2  36.8  34.6  35.0  66.6  79.4  58.8  53.0  56.2  46.8  69.4  81.8  46.8  94.8  122.8  124.2  154.0 155.0  111.4  86.2  37.8  90.4  96.6  47.6 43.0  45.6  103.0  56.2  45.2  63.6  112.0  52.1 100.4  62.4  198.9 182.4  89.4 102.0  48.2  44.2  47.8  77.8  89.8  97.8 104.4  142.6  118.8  119.0  93.4  110.4  47.2  53.4  63.6  127.6  127.9  67.2  119.8  69.4  105.2  90.2  88.6  75.8  77.2  95.2  98.0  105.0  94.0  108.8  181.6  190.0 j 99.2  153.9  164.7  107.8  85.6  80.2  72.8  64.8  62.8  76.2  82.4  98.0  154.8  144.8  83.0  84.4  70.8  69.4  100.6  74.4  70.4  103.8  70.6  66.0  90.0  70.0  60.0  108.2  100.0  89.6  93.2  88.4  80.0  76.6  66.6  70.6 69.0  65.2  82.2  95.0  77.0  51.6  86.2  76.8  53.6  65.6  81.2  78.8  65.0  49.4  67.8  56.6  78.0  60.0  68.0  55.4  58.4  75.4  57.8  71.2  71.6  98.0  67.6  70.8  66.4  87.4  73.2  65.0  51.2  Tt oo co o m rv oo o>  1/26/94  1/12/94  12/29/93  112/15/93  89.2  99.4 127.2  175.6  123.2  144.1  118.9  132.8 [ 75.0  CO  74.4  68.2  87.6  71.8  59.6  49.8  87.2  72.8  76.8  o  93.2  CO CM  o  12/1/93  CM  144.9  rv  75.2  co 76.5  CO  56.0  in 109.9  O)  11/17/93  168.8  CM  122.4  121.3  co 98.8  co  105.6  t  89.5  Tt  82.0  T—  112.4  m  56.8  CO  63.2  rv  10/20/93  co  10/6/93  o  Date  Time (day)  Leachate Iron (mg/L)  F.13  90S  Column #  Appendix F. Leachate Characteristics Data  283  Iron  Tt  284  Appendix F. Leachate Characteristics Data  Tf  CM  CD  CO  10.0  10.8  10.0 Tf  oo oo'  oo co co co  Tf  rv  CD  CD  CM  in o  10.4  10.2  CO Tf  o o  Tf  00  CO  Tf  Tf  Tf  CO  CO  Tf  CM  CM  CO  tri  CM Tf  CM Tf  Tf  rv  CO  cvi cvi  00  o cq  Tf  cp  CM  CM  CM  GO  CM  O  CO  CO  iri  CO  q  CO  00  CM  co o T f co cd co  CM  oo CM o CO T f cd tri T f cd cvi  CO  CO  CO  CD  CM  CM  o T f CO co co ui tri CO  00  cri co co tri  Tf  Tf  Tf  Tf  Tf  o  Tf  CM  co tri  CM Tf  CM  00  01  in  oo 0 1 t v 00 co o CM 10 r v o co co co co T f  9/28/94  Tf O) CM  8/31/94  CM  8/10/94  CM  7/27/94  in co Tf co  6/8/94  CO CM  6/29/94  5/4/94  CM  5/25/94  3/23/94  4/20/94  CO 01  co tn co  4/6/94  CM 00  19.8  13.0  CD o cd cvi cvi  16.0  oo  CM CM co T f co CM o cd cd cd c\i cvi cvi cvi cvi  Tf  CM  o co CM o cd cd cd  Tf  tri  CM Tf  Tf  Tf  CM  rv  CO Tf  o o co T f CM o o cd cvi cvi cvi cvi cvi  Tf co T f CM o co co tri tri tri tri  ai  oo d  Tf  CO  co o  d  CO  00 Tf  Tf  od  3/9/94  co co CM o o oq cvi CM cvi cvi cvi  CD  Tf  Tf  2/23/94  in cp  19.0  rv  22.2  CM Tf  Tf  Tf  11/16/94  13.8 11.6 17.0 10.8 10.8  CO  co  d  oo d  10/19/94  17.6 15.6 12.8  10.2  13.4  21.4 20.0  10.2 22.8 15.2 14.6  16.2  15.4  Tf  CO  30.2  35.6  17.8  23.4 18.4 19.6 29.0  o cri  12.4  15.8  Tf  co oo 00 oo 00 cri cd co tri tri tri  2/9/94  1/26/94  Tf  o T f co co cvi tri tri tri tri  27.4  28.6  10.8  21.0 10.4 11.0  17.0 15.0  14.6  CM Tf  28.2 39.4 19.2 25.0 44.0 1/12/93  23.6  33.2 12/29/93  12/15/93  54.2 33.8  39.4  39.8 47.8  49.0 61.4 51.6 54.8 70.6 47.2  11.4  24.4 13.4 11.0 18.6  18.8 13.6  Tf  35.8  12.2  29.2 26.0  CO CO  40.0  17.0  14.6  27.81 16.2 12.6 25.4  24.4  22.8  31.4 19.6 16.4 33.8 19.8  26.8  46.0 28.6 28.4  co  GO  cd  50.4  30.0  34.0  42.0  47.2 36.0 30.6  32.4  57.4 43.6 40.6 63.2 51.2 43.0 57.2 43.4  Tf  Tf  58.2  41.8  46.2  62.0 78.0 64.0  65.0  106.8 111.2 90.8 155.6  98.0 92.0  116.0 121.2  76.0 64.0  133.6 88.4  54.0 58.0 64.0  103.6  Tf  CM  Tf  CM  00 CD o CM CM CM cvi cvi cvi cvi cvi cvi cvi  rv  76.0  98.4  q  rv  90.0 84.0  q  oo co oo oo co co co d d d d d d d  Tf  Tf  q  °s  CO  O  CM  q  Tf  CM  d  co o  CM  CM  o c\i  co cd  ID  78.0  CM  CM  Tf  CM  cri  76.0  CO O)  92.0  Tf GO  oo  CO  at co d co cb  Tf  CM  CM  o rv  co o oo oo cvi cvi Tf Tf  CM  Tf  CD  CM Tf  Tf  CO  Tf  in  CM  o T f o o cp cd co' cvi cvi cvi  00  CO  CM  Tf  CM  co o o t v cri ai od co  CO  oo rv  o Tf  o co CM CM co cd cvi cvi cvi d  Tf  co oo  68.0  134.4  CM rv  CO  Tf  Tf  tri  12/1/93  158.0  Tf  o co  CM  Tf  Tf oo T f cb od ob cri  co CO o co co' co'  oo T f o cri cd tri  I  353.61  132.8 148.4 129.6 147.2 115.2 CM Tf  11/17/93  Tf  60.0  268.8  458.8  144.4  344.4  273.6  301.2  393.2  386.8  259.2  Time (day)  o  10/6/93  Date  Column #  Leachate Sodium (mg/L)  CM  282.2  473.6  CO  Tf  Tf  CM  co cp cp o o cri *— Tf Tf  rv  CM  co tri  CM  OS  406.0  Tf  CM  rv  OS  471.6  ID  361.2  417.4 500.6  CO  488.0  268.6 422.2  rv  370.8  479.4 309.8 371.8 443.2  493.8  co  oo  co  0'9  0>  rv  ai cd tri tri  Tf  cri  rv  OS  O  274.0  CM  338.4  co  274.0  Tt  351.6  U)  378.8  273.0  Tf  421.6  ID  402.8  CO  o co  OS  CM Tf  342.4  rv  338.4  co  214.4  Sodium  10/20/93  F.14  Appendix F. Leachate Characteristics Data  F.15  Chlorides co  |v  o o LO  o co CM  o cn  o LO  o o  O  o  o  o  IV  rf rf  CO CM  co  LO  o rf  CD  O  3  o r-  o rr  o o  co  IO  LO  o  o  o  8 8  o o  o  s 8  o CO  8  CO co  r?  o  o  1—  IV  oo  £  O CM CO  rr  CO  CM  o  o  o  CM  o  LO  o  IV  iv  co CM  LO r» LO  o to CM  •<t  o to  o  o  o  o o  3  LO rr  o to  cn O)  rr cn  o LO  o co  co rr  o  O)  LO CM  co  LO LO LO  CO  o  CO  o  CM  00  co  o CM rr  o co  o rf  o CM  00 |v  co LO  |v  o co LO  o  o to  o T  CM co  rt CM  o  s  o  8  rLO  3  00  o rr  co  0)  o co CM  o  CO  rr  o CM co  o LO CM  I  oo cn  $  cn CM  co  o o to  o o CM  o rr  o o  rrr  CM co  CM  o  o CO CM  o CD  y—§_  0> Iv  rr LO  o  o  o  s  oo CO  CM  o  r-  3  CM  26/1/94  rr  29/12/93  LO  CM  15/12/93  rr  O) rr  o  LO  cn  CM  LO  1—  rr  CM rr  17/11/93  Time (day) Date  Column #  oo  CM  20/10/93  co rf  CM  CO LO  1/12/93  CO  1 Leachate Chlorides (mg/L)  1—  to  285  Appendix G  Gas Characteristics Data  G.l  Composition of Gas  Gas Composition (% by volume) Column #1 Time(day) Date N-2 CH-4 CO-2 0-2 Gas 5.0 24.0 0.0 0 71.0 10/4/93 4.8 29.0 0.5 14 65.7 10/18/93 0.6 10.1 27.0 28 62.3 11/1/93 8.6 32.1 0.6 42 58.6 11/15/93 6.1 34.9 0.4 56 58.5 11/29/93 0.0 4.7 36.0 70 58.0 12/13/93 6.5 40.6 1.1 84 51.7 12/27/93 3.9 39.8 0.3 98 56.0 1/10/94 7.6 43.1 1.6 127 47.5 2/8/94 1.6 6.9 45.1 140 46.3 2/21/94 3.4 46.2 0.0 165 50.3 3/18/94 3.4 47.5 0.7 168 48.3 3/21/94 0.4 2.4 45.8 182 51.3 4/4/94 0.0 2.0 44.6 196 53.2 4/18/94 0.5 1.3 45.5 210 52.5 5/2/94 0.6 22 47.8 231 49.4 5/23/94 2.2 42.8 0.0 245 55.0 6/6/94 0.4 1.9 48.0 266 49.5 6/27/94 0.3 1.1 47.6 294 50.9 7/25/94 0.0 49.6 0.0 308 50.3 8/8/94 0.0 48.5 0.0 329 51.4 8/29/94 0.0 55.7 0.0 357 44.3 9/26/94 0.0 51.4 0.0 378 48.6 10/17/94 1.3 57.1 0.4 396 41.1 11/4/94 0.0 0.0 51.6 406 48.4 11/14/94 0.0 51.3 0.4 445 48.3 12/23/94 0.0 53.0 0.4 462 46.6 1/9/95 0.4 0.0 51.6 469 48.0 1/16/95 0.3 0.0 58.1 476 41.6 1/23/95 0.0 59.9 0.4 483 39.7 1/30/95 0.5 4.7 55.8 497 39.0 2/13/95 0.4 8.4 50.7 511 40.4 2/27/95 0.0 60.9 0.4 525 38.7 3/13/95 0.0 63.4 0.4 539 36.1 3/27/95 0.0 63.2 0.0 546 36.8 4/3/95 0.0 0.0 55.4 553 44.6 4/10/95 0.0 0.0 54.2 560 45.8 4/17/95 0.0 53.9 0.0 567 46.1 4/24/95 0.0 54.1 0.0 581 45.9 5/8/95 0.0 54.0 0.0 599 46.0 5/26/95 0.0 0.0 53.6 630 46.4 6/26/95  !  I  I  Column #2 CO-2 0-2 N-2 67.0 0.3 9.3 61.5 0.5 8.5 58.7 0.5 13.1 49.0 1.4 13.0 52.3 0.9 9.0 54.8 0.4 6.2 45.0 1.7 8.3 54.6 0.3 3.6 47.0 1.4 5.8 45.5 1.0 5.2 49.2 0.6 2.4 48.6 0.6 2.6 2.4 48.5 0.5 47.6 0.5 2.3 50.7 0.0 1.9 46.2 0.5 1.9 56.4 0.0 2.0 43.9 0.4 1.8 33.4 0.0 0.0 49.4 0.0 0.0 44.8 0.0 0.0 45.7 0.0 0.0 0.0 0.0 46.3 39.5 02 0.8 0.0 0.0 45.1 44.9 0.3 0.0 0.3 0.0 44.9 41.9 0.0 0.0 40.0 0.5 0.0 38.6 0.4 0.0 0.3 2.8 38.1 38.8 0.3 8.0 37.9 0.0 0.0 34.2 0.4 0.0 36.7 0.0 0.0 41.8 0.0 0.0 43.3 0.0 0.0 43.7 0.0 0.0 44.1 0.0 0.0 43.7 0.0 0.0 44.2 0.0 0.0  286  I CH-4 23.7 29.5 27.7 36.6 37.6 38.6 44.9 41.4 45.7 48.3 47.8 48.1 48.6 49.6 47.4 51.4 41.5 53.8 66.6 50.6 55.1 54.3 53.7 59.4 54.9 54.7 54.7 58.0 59.5 61.0 58.8 52.9 62.0 65.3 63.3 58.2 56.7 56.3 55.9 56.3 55.8  CO-2 67.0 61.5 52.2 53.6 54.6 55.6 50.6 54.4 48.5 47.0 50.7 51.0 50.4 51.5 49.8 49.7 53.4 60.8 56.6 48.1 49.3 45.4 51.3 40.3 48.0 47.1 47.0 45.7 39.9 38.1 36.3 37.2 36.2 33.5 35.8 41.6 43.4 43.5 45.4 46.9 44.8  I  I  Column #3 0-2 N-2 0.3 10.0 0.5 9.0 1.6 10.7 0.5 6.3 0.3 4.8 0.3 3.9 0.8 4.7 0.0 2.7 1.6 5.6 1.4 5.0 0.6 2.3 0.6 2.5 2.3 0.6 0.5 2.3 0.5 2.2 0.4 1.7 0.0 1.4 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.4 1.5 0.3 0.0 0.4 0.0 0.3 0.0 0.3 0.0 0.3 0.0 0.3 0.0 0.3 0.0 0.2 8.4 0.1 0.0 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0  I  I  I  Column #4 CH-4 CO-2 0-2 N-2 22.7 64.0 1.6 16.0 29.0 64.0 1.0 11.0 35.4 63.3 0.3 8.6 39.6 37.3 5.2 23.6 40.0 55.2 0.8 8.7 40.1 54.3 0.6 7.3 43.8 36.8 4.4 18.1 42.6 35.9 4.4 15.9 44.3 44.5 1.5 7.3 46.6 30.6 3.7 12.9 46.4 45.8 0.7 3.1 45.8 46.4 0.5 2.6 46.6 47.8 0.6 2.1 45.6 47.5 0.6 2.5 47.3 47.0 0.5 2.1 48.2 45.7 0.4 1.8 45.1 52.8 0.0 1.2 39.1 57.0 0.0 0.0 42.9 55.6 0.0 0.0 51.8 46.0 0.0 0.0 50.7 45.6 0.3 0.0 54.6 39.3 0.3 0.0 0.0 48.7 45.4 0.0 57.7 38.0 0.3 1.3 51.7 44.3 0.3 0.0 52.4 45.0 0.4 0.0 52.6 44.4 0.4 0.0 54.0 43.8 0.4 0.0 59.7 37.2 0.3 0.0 61.6 35.0 0.5 1.5 63.4 31.3 0.2 0.0 54.1 29.3 1.2 11.2 63.7 29.4 0.0 0.0 66.1 28.1 0.7 3.0 64.2 31.3 0.0 0.0 58.4 35.3 0.0 0.0 56.5 39.8 0.0 0.0 56.5 41.3 0.0 0.0 54.6 44.3 0.0 0.0 53.1 43.5 0.0 0.0 55.2 45.2 0.0 0.0  CH-4 19.4 24.0 27.7 33.8 35.2 37.7 40.5 43.7 46.5 52.7 50.4 50.4 49.5 49.3 50.4 52.0 45.9 43.0 44.4 54.0 54.0 60.3 54.5 60.3 55.4 54.6 55.2 55.8 62.4 63.0 68.4 58.2 70.6 68.2 68.7 64.7 60.2 58.7 55.7 56.5 54.8  287  Appendix G. Gas Characteristics Data  Gas Composition (% by volume) Column #6 Column #5 Time(day) CO-2 0-2 N-2 CH-4 CO-2 0-2 N-2 1.0 13.0 20.0 49.3 4.3 23.4 0 66.0 10/4/93 0.5 10.2 24.3 59.2 0.5 10.3 14 65.0 10/18/93 28 63.5 0.4 10.3 25.8 54.7 0.7 15.2 11/1/93  Date  Column #7 CH-4 CO-2 0-2  N-2  Column #8 CH-4 CO-2 0-2  N-2  CH-4  23.0 61.5  1.1  8.0 29.5 59.1  1.6  9.4 29.9  30.0 59.0  0.4  5.5 35.1 58.6  0.4  5.0 36.0  29.3 56.9  0.4  4.2 38.5 58.3  0.2  3.5 37.8  0.5  4.1 44.3 45.5  6.1 46.9 2.5 44.1  11/29/93  42 59.7 56 61.2  0.6 0.0  8.1 31.5 43.5 5.6 33.1 52.6  2.0 16.8 37.7 51.0 0.6 8.5 38.2 56.3  0.0  1.6 42.1  53.3  1.5 0.0  12/13/93  70 58.9  0.4  4.0 36.6 46.8  0.3  8.0 44.8 50.5  0.3  2.7 46.4 52.1  0.3  2.5 45.1  12/27/93  0.6  11.1 51.2 48.0  0.5  2.7 48.7 50.4  0.4  2.5 46.6  1.7  4.0 40.9 35.6 7.4 39.7 42.0  2.2  1/10/94  84 54.4 98 51.1  1.5  8.4 48.0 45.3  2.4  9.5 42.7 51.6  0.2  1.9 46.2  2/8/94  127 46.1  1.4  5.5 46.9 40.8  1.1  5.5 52.5 46.1  1.1  4.8 47.8 47.5  1.3  4.8 46.3  2/21/94  140 43.4  1.2  5.4 52.7 43.1  1.4  5.7 49.7 44.5  1.4  5.7 48.2  165 48.4  0.9  4.5 50.8 40.6 3.4 47.3 45.2  1.3  3/18/94  0.7  2.4 51.6 48.1  0.6  2.3 49.0 50.0  0.5  3/21/94  168 50.1  0.5  2.0 47.2 47.4  0.6  1.9 50.1 49.5  0.5  1.9 48.0 52.7  0.0  2.4 47.0 1.9 45.4  0.5  0.5  0.8 49.6 47.1  0.5  2.1  50.3 52.5  0.5  1.4 45.6  4/18/94  182 50.2 196 50.2  1.7 47.5 49.0 2.0 47.1 48.4  0.2  0.9 50.3 46.9  0.5  2.1 50.4 51.9  0.6  1.7 45.7  2.1 47.3 52.6 1.7 48.9 47.3  0.4  1.1 45.8 48.2  0.5  1.8 49.4 52.8  5.2  1.3 40.7  0.4  1.6 50.7 46.0  0.4  1.5 51.9 49.9  0.5  1.7 47.8  0.4  1.3 50.9 45.1  0.5  1.5 52.9 48.9  0.4  1.5 49.2  0.0  0.0  0.9 54.3 48.2  0.3  0.0  0.0 50.2 60.3  0.0  1.6 49.8 0.0 39.7  11/15/93  4/4/94  0.5  5/2/94  210 49.8  0.7  5/23/94  231 48.9  0.5  6/6/94  245 49.2  0.4  6/27/94  0.0  7/25/94  266 47.8 294 50.1  3.7 49.3 47.2 1.4 50.8 50.7 1.0 48.6 57.5 0.0 48.5 48.9  0.0  1.1 48.2 44.8 0.0 42.5 49.8  0.0  0.0 51.1 44.0  0.0  0.0 56.0 47.9  0.0  0.0 52.1  0.0  0.0 54.7 40.0  0.0  1.0 59.0 48.3  0.0  0.0 51.7  0.0  0.0 54.0 45.9  0.0  0.0 54.1 46.6  0.0  0.0 53.4  8/8/94  308 51.5  0.2 0.0  8/29/94  329 49.1  0.0  9/26/94  357 44.7  0.4  0.0 50.8 45.3 0.0 54.9 46.0  0.0  0.0 51.9 46.9  0.0  0.0 53.1 43.6  0.0  0.0 56.4 58.4  0.0  0.0 41.6  0.3  1.5 56.7 40.9  0.3  1.3 57.5 35.9  0.5  1.7 61.8 40.4  0.3  1.4 57.9  0.0  0.0 48.8 47.6  0.3  0.0 52.1 42.3  0.4  0.0 57.3 47.5  0.0  0.0 52.5  0.0  0.3  0.0 52.1 42.7  0.6  0.0 56.7 46.4  0.3  0.0 53.3  0.3  0.0 54.7 40.0  0.4  0.0 59.5 47.1  0.0  0.0 52.9  10/17/94  378 48.1  10/28/94  389  10/31/94  392  11/4/94  396 41.4  11/10/94  402  11/14/94  406 51.1  11/21/94  413  12/23/94  445 49.5  1/9/95  462 50.1  0.0  0.0 50.5 47.5 0.0 49.8 44.9  1/16/95  469 47.3  0.3  0.0 52.4 45.8  0.4  0.0 53.8 45.2  0.4  0.0 54.4 47.3  0.0  0.0 52.7  1/23/95  476 41.3  0.3  0.3  0.0 60.8 40.4  0.5  0.0 59.0 40.2  0.4  0.0 59.4  1/30/95  483 39.2  0.3  0.0 58.3 38.8 0.0 60.5 35.9  0.4  0.0 63.7 39.4  0.5  0.0 60.1 38.7  0.3  0.0 61.0  2/13/95  0.4  0.0 65.2 38.8  0.4  0.0 60.8 37.7  0.3  0.0 62.1  0.2  0.0 62.8 34.5 0.0 63.3 35.3  0.3  2/27/95  497 36.8 511 36.5  0.5  8.8 55.7  38.0  0.4  6.5 55.1  3/13/95  525 34.3  0.0  0.0 65.7 34.3  0.0  0.0 65.7 37.7  0.0  0.0 62.3 36.7  0.0  0.0 63.3  0.4  0.0 68.5 35.5  0.4  1.5 62.4 34.6  0.4  0.0 65.0  3/27/95  539 32.3  0.4  0.0 67.2 31.0  4/3/95  546 36.6  0.0  0.0 66.2 39.1  0.0  0.0 60.9 39.0  0.0  0.0 61.0  0.0  0.0  0.0 58.8 41.1  0.0  0.0 58.8 42.6  0.0  0.0 57.4  4/17/95  553 40.8 560 42.8  0.0 63.4 33.8 0.0 59.2 41.2  0.0  4/10/95  0.0  0.0 57.2 42.6  0.0  0.0 57.4 42.2  0.0  0.0 57.8 43.7  0.0  0.0 56.3  4/24/95  567 43.7  0.0  0.0 56.2 43.3  0.0  0.0 56.6 42.7  0.0  0.0 57.3 44.0  0.0  0.0 55.9  5/8/95  581 44.5  0.0  0.0 55.5 43.2  0.0  0.0 56.8 42.1  0.0  0.0 57.9 43.8  0.0  0.0 56.2  5/26/95  599 44.7  0.0  0.0 55.3 43.5  0.0  0.0 56.4 43.2  0.5  0.0 56.3 44.3  0.0  0.0 55.7  630 45.1  0.0  0.0 54.9  0.0 55.6 44.2  0.0  0.0 55.8 44.7  0.0  0.0 55.3  6/26/95  44.61  0.0  288  Appendix G. Gas Characteristics Data  Gas Composition (% by volume) Column #10 Column #11 Column #9 N-2 CH-4 CO-2 N-2 CH-4 CH-4 CO-2 0-2 0-2 N-2 CO-2 0-2 Time(day) Date 57.0 3.8 31.5 7.4 80.0 0.5 11.0 8.5 11.6 23.6 0.8 0 63.9 10/4/93 9.5 14.4 45.1 4.6 42.2 8.1 75.5 0.6 8.2 31.2 14 60.0 0.6 10/18/93 71.0 0.6 12.7 15.7 28 57.7 0.3 5.7 36.2 30.5 15.6 36.2 17.7 11/1/93  Column #12 CO-2 0-2  N-2  CH-4  64.0  2.0 22.0 12.0  56.0  3.0 23.0 18.0  67.6  0.5  13.0 18.8  42 51.5 56 57.4  0.6  2.4 30.7 14.3 67.9 1.5 23.4 14.4 69.6  0.5 10.4 21.1 56.5 0.0 6.9 23.5 68.5  15.9 25.9  0.0  5.3 42.6 52.6 2.5 40.1 60.7  1.7  11/29/93  0.5  8.3 22.6  12/13/93  70 51.4  0.3  2.8 45.5 63.6  0.5 18.5 17.5 67.5  0.4  5.5 26.5 61.0  0.5  9.0 29.4  12/27/93  84 49.0  0.5  4.0 29.0 21.8 63.8  0.0  4.8 31.2 50.3  2.4  13.7 33.5  1/10/94  98 49.6  0.3  2.6 47.8 45.0 2.3 47.8 64.6  0.5 13.4 21.4 64.4  0.2  3.8 31.5 58.8  0.3  7.3 33.6  2/8/94  127 45.0  1.2  4.9 48.7 62.4  1.5  10.4 25.6 57.8  1.4  5.4 35.3 40.7  3.7  15.8 39.7  2/21/94  140 42.7 165 47.6  1.2  5.6  17.9 43.0  0.8  4.8 42.9  3/21/94  168 48.3  0.8 0.7  5.6 39.8 33.5 3.2 38.2 51.4  0.6  4.8 51.1 38.9 5.2 20.9 34.9 53.3 2.4 49.3 62.2 0.5 3.6 33.7 57.8 2.2 48.8 40.9 18.4 8.3 32.3 57.5  1.2  0.6  2.8 38.9 39.9  3.3 10.7 46.1  4/4/94  182 51.1  0.5  1.4 47.0 59.5  0.8  3.4 36.2 51.1  0.6  2.8 45.5 44.5  0.7  4.6 50.1  4/18/94  196 49.6  0.5  2.9 37.2 47.0  0.5  3.0 49.3 41.6  0.5  4.4 53.4  210 51.1  0.2  2.1 47.8 59.4 1.5 47.1 56.7  0.5  5/2/94  0.6  3.3 39.4 48.3  0.5  2.5 48.6 37.5  0.9  4.9 56.7  5/23/94  231 48.4  0.4  0.6  2.7 44.9 40.5  0.4  2.4 56.6 32.9  0.6  3.5 62.8  6/6/94  245 48.1  0.5  1.5 49.5 51.8 1.5 49.8 51.6  0.4  2.1 45.9 42.1  0.4  10.1 47.3 34.1  0.5  3.8 61.5  6/27/94  266 46.6  0.4  2.2 50.8 48.9  0.4  2.1 48.5 55.9  0.0  0.0 44.1 33.9  0.4  3.7 62.0  7/25/94  294 49.7  0.2  0.3  1.2 48.1 46.0  0.4  15.0 38.0 39.4  0.2  0.9 59.5  8/8/94  308 50.2  0.0  0.0 50.1 50.4 0.0 49.8 39.8  1.6  3.7 54.9 43.2  0.0  3.8 52.9 40.1  0.5  0.0 59.4  8/29/94 9/26/94  329 48.1 357 43.7  0.4 0.0  0.0 51.5 44.1 0.0 56.3 44.7  0.0  0.0 55.9 42.0  0.0  0.0 58.0 37.0  0.0  0.0 55.3 38.8  0.0  1.4 59.7 40.7  0.0 0.0  1.0 61.9 1.7 57.6  10/17/94  378 49.3  0.0  0.0 50.7 74.8  0.0  0.0 25.1  36.9  0.0  0.0 63.1 50.3  0.0  0.9 48.8  10/28/94  389  10/31/94  392 0.3  1.2 60.3 36.4  0.4  1.7 61.4 33.4  0.8  1.4 64.3 31.1  0.3  2.1 66.4  0.3  0.0 51.0 42.2  0.0  0.0 57.8 36.8  0.3  0.0 62.9 36.3  0.3  1.0 62.4  10.3 56.3 32.2  0.4  0.0 67.3  11/15/93  3/18/94  11/4/94  396 38.1  11/10/94  402  11/14/94  406 48.7  11/21/94  413  12/23/94  445 44.5  0.4  0.0 55.1 41.1  0.4  0.0 58.5 32.8  0.5  1/9/95  462 44.5  0.5  0.0 54.9 38.9  0.4  0.0 60.6 34.8  0.4  1.5 63.3 34.2  0.0  0.0 65.8  1/16/95  469 44.8  0.0  0.0 55.1 42.6  0.4  0.0 56.9 41.1  0.0  0.0 58.8 36.7  0.4  0.0 62.8  1/23/95  476 36.6  0.4  0.0 63.0 39.6  0.5  0.0 59.8 36.6  0.3  0.0 63.0 33.6  0.4  0.0 66.0  1/30/95  483 33.0  0.4  0.0 66.5 39.2  0.4  0.0 60.3 34.4  0.4  0.0 65.2 31.9  0.4  0.0 67.7  2/13/95  497 29.8  0.4  0.0 69.7 37.7  0.4  0.0 61.8 33.6  0.3  4.0 62.0 28.9  0.3  0.0 70.7  511 27.5  0.3  8.9 63.3  33.8  0.4  8.8 57.0 28.1  0.4  8.5 62.9  0.0  0.0 58.4 34.4  0.0  0.0 65.6 24.2  0.0  5.7 70.1  2/27/95 3/13/95  525 24.6  0.0  4.1 71.2 41.6  3/27/95  539 25.7  0.4  2.6 71.2 35.7  0.4  0.0 63.8 29.4  0.4  0.0 70.2 24.9  0.4  3.5 71.1  4/3/95  546 28.8  0.0  0.0 71.1 39.0  0.0  0.0 60.9 31.4  0.0  0.0 68.6 28.2  0.0  0.0 71.7  4/10/95  553 33.7  0.0  0.0 66.3 41.1  0.0  0.0 58.8 35.2  0.0  0.0 64.8 32.4  0.0  0.0 67.6  4/17/95  560 38.6  0.0  0.0 61.4 42.8  0.0  0.0 57.2 39.2  0.0  0.0 60.8 38.1  0.0  0.0 61.9  4/24/95  567 40.5  0.0  0.0 59.5 42.7  0.0  0.0 57.2 40.3  0.0  0.0 59.6 40.7  0.0  0.0 59.3  5/8/95  581 41.5  0.0  0.0 58.4 43.0  0.0  0.0 57.0 41.1  0.0  0.0 58.8 42.3  0.0  0.0 57.7  5/26/95  599 42.8  0.0  0.0 57.2 42.9  0.0  0.0 57.1 41.4  0.0  0.0 58.6 43.9  0.0  0.0 56.1  0.0  0.0 55.8 43.9  0.0  0.0 56.1 42.3  0.0  0.0 57.7 45.2  0.0  0.0 54.8  6/26/95  630 44.2  289  Appendix G. Gas Characteristics Data  Gas Composition (% by volume) Column #14  Column #13 Time(day) CO-2  Date 10/4/93  0  73.0  0-2  CH-4  N-2  CO-2  0-2  N-2  Column #15 CH-4  CO-2  0-2  N-2  CH-4  0.8  18.2  7.0  75.0  0.0  4.5  19.5  76.5  0.6  8.5  14.4  11.2  70.0  0.3  4.0  25.7  68.0  1.0  8.0  23.0  10/18/93  14  60.0  2.5  26.3  11/1/93  28  61.0  2.2  24.5  12.1  71.8  0.3  2.7  25.2  69.2  0.3  7.1  23.4  11/15/93  42  64.6  1.0  15.9  70.5  0.0  15.2  0.5 0.0  1.7  32.3 30.3  57.7 56.3  0.8 0.0  9.5 7.5  32.0  56  64.0 67.9  3.2  11/29/93  18.5 14.3  12/13/93  70  65.5  0.6  13.5  20.0  62.9  0.4  2.4  34.3  54.1  0.4  6.2  39.2  12/27/93  84  58.2  1.7  15.4  24.7  42.3  4.3  11.4  42.0  45.5  1.1  8.0  45.3  1/10/94  98  65.5  0.4  9.5  24.6  46.1  5.6  21.9  26.3  49.3  0.3  4.8  45.4  2/8/94  127  62.7  1.3  8.3  27.6  45.8  3.0  9.9  41.1  45.6  1.3  5.0  47.9  2/21/94  140  605  1.4  7.2  31.1  51.3  1.5  6.6  40.5  42.1  0.9  5.9  51.0  4.1  32.1  55.0  0.5  2.5  41.9  47.3  0.7  3.0  48.9  3.0  48.8  36.2  3/18/94  165  62.9  0.8  3/21/94  168  60.0  1.2  4.9  33.7  39.7  3.6  8.4  48.1  47.3  0.8  4/4/94  182 196  59.0  0.8  4.1  35.9  45.9  0.7  3.0  50.3  53.6  0.5  1.7  44.2  4/18/94  58.5  0.6  3.3  37.6  43.3  0.6  3.0  52.9  51.4  0.4  2.1  46.0  5/2/94  210  58.3  0.6  3.1  37.9  34.8  2.1  6.0  57.0  51.4  0.5  2.0  46.0  5/23/94  51.1 49.7  0.9 0.7  3.0 2.8  44.9  2.3  58.0  51.5  0.4  1.5  46.5  46.7  39.1 40.9  0.5  6/6/94  231 245  0.5  2.2  56.3  49.5  0.3  1.4  48.8  6/27/94  266  51.8  0.0  0.0  48.2  50.0  0.0  0.0  50.0  49.5  0.7  1.3  48.5  7/25/94  294  51.2  0.0  0.0  48.7  43.5  0.3  0.0  56.2  54.4  0.0  0.7  44.8  8/8/94  308  41.4  0.8  2.3  55.6  39.6  0.3  0.0  60.0  50.1  0.3  0.0  49.5  329  42.8  0.0  1.2  56.0  39.4  0.0  0.0  60.6  46.5  0.0  0.0  53.4  0.0  57.3  38.3  0.0  0.0  61.7  51.0  0.0  0.0  49.0  8/29/94 9/26/94  357  42.6  0.0  10/17/94  378  44.9  0.0  0.0  55.1  49.8  0.0  0.0  50.2  52.1  0.3  0.0  47.6  10/28/94  389  10/31/94  392  11/4/94  396  34.9  0.4  1.9  62.7  36.0  0.0  1.1  62.8  44.0  0.3  1.1  54.4  11/10/94  402  11/14/94  406  41.9  0.3  0.0  57.7  38.8  0.4  0.0  60.8  50.2  0.0  0.0  49.8  11/21/94  413  12/23/94  445  43.9  0.4  0.0  55.7  33.8  0.5  0.0  65.6  48.9  0.4  0.0  50.7  1/9/95  462  40.9  0.3  0.0  58.7  33.5  0.4  1.6  64.5  49.5  0.2  0.0  50.2  1/16/95  469  43.8  0.4  0.0  55.7  39.3  0.0  0.0  60.7  51.3  0.0  0.0  48.6  1/23/95  476  37.6  0.4  0.0  61.9  34.3  0.3  0.0  65.3  46.9  0.3  0.0  52.7  1/30/95  483  34.3  0.3  0.0  65.4  32.5  0.6  0.0  66.9  46.8  0.3  0.0  52.0  2/13/95  497  30.2  0.5  0.0  69.3  30.3  0.5  0.0  69.2  45.4  0.4  0.0  54.1  2/27/95  511  27.9  0.2  0.0  71.8  29.1  0.8  9.2  60.8  3/13/95  525  28.6  0.0  0.0  71.3  27.0  0.0  3.7  69.2  46.9  0.0  0.0  53.1  3/27/95  539  25.8  0.5  2.3  71.3  27.5  0.5  0.0  72.0  43.3  0.4  0.0  56.3  4/3/95  546  28.4  0.0  0.0  71.6  31.0  0.0  0.0  69.0  45.6  0.0  0.0  54.4  4/10/95  553  34.0  0.0  0.0  65.9  35.7  0.0  0.0  64.3  45.9  0.0  0.0  54.0  4/17/95  560  39.5  0.0  0.0  60.5  39.9  0.0  0.0  60.1  45.8  0.0  0.0  54.2  4/24/95  567  41.6  0.0  0.0  58.4  41.3  0.0  0.0  58.7  45.8  0.0  0.0  54.2  5/8/95  581  43.1  0.0  0.0  56.8  41.8  0.0  0.0  58.2  45.1  0.0  0.0  54.9  5/26/95  599  43.6  0.0  0.0  56.4  42.5  0.0  0.0  57.5  45.4  0.0  0.0  54.6  6/26/95  630  44.1  0.0  0.0  55.8  44.1  0.0  0.0  55.9  45.6  0.0  0.0  54.4  290  Appendix G. Gas Characteristics Data  Gas Composition (% by volume) Column #17  Column #16 Date 10/4/93  CO-2  Time(day) 0  57.2  CH-4  N-2  0-2  CO-2  0-2  N-2  Column #18 CH-4  CO-2  N-2  0-2  CH-4  0.3  0.8  41.7  76.0  1.0  15.0  8.0  54.0  0.6  32.4  13.0  48.2  65.5  2.3  18.6  13.6  53.0  0.5  22.5  24.0  0.5  18.8  11.4  55.3  0.7  18.3  25.6  10/18/93  14  49.4  0.4  2.0  11/1/93  28  53.1  0.3  3.3  43.2  69.3  11/15/93  42  47.5  0.0  0.0  52.5  61.6  1.0  20.3  17.1  48.9  0.6  13.7  36.8  11/29/93  56  45.1  0.0  1.8  53.1  60.2  0.6  17.7  21.4  47.5  0.5  9.5  42.5  12/13/93  70  44.9  0.0  1.6  53.5  51.6  2.0  20.9  25.3  47.7  0.4  6.9  44.9  12/27/93  84  36.7  1.7  4.4  57.2  49.2  1.5  19.1  30.1  46.4  0.5  5.4  47.6  1/10/94  98  43.7  0.0  1.2  55.1  55.2  0.4  13.8  30.5  49.4  0.3  3.0  47.3  2/8/94  127  35.5  2.0  7.4  55.0  46.7  2.2  14.4  36.6  44.6  1.4  6.0  48.0  1.2  4.8  55.9  49.6  1.0  9.0  40.3  42.6  1.0  4.7  51.7  2.0  52.7  54.9  0.8  5.1  39.1  46.1  0.5  1.8  51.5  6.5  40.7  45.0  0.6  2.4  52.0  2/21/94 3/18/94  140 165  38.0 44.7  0.6  3/21/94  168  42.9  1.0  3.1  53.0  51.6  1.0  4/4/94  182  43.5  0.4  2.1  54.0  59.5  0.7  3.4  36.3  44.0  0.5  1.9  53.5  4/18/94  196  43.5  0.0  2.6  53.3  59.9  0.5  2.8  36.7  43.4  0.5  2.0  54.1  5/2/94  210  42.5  0.6  2.2  54.6  63.3  0.4  34.3  43.1  0.3  1.9  54.5  5/23/94  231  43.8  0.4  54.2  245  42.8  0.4  55.4  59.3 57.2  0.5 0.5  38.7  6/6/94 6/27/94  1.5 1.4  1.9 1.5 1.5  40.8  41.7 41.4  0.4 0.5  1.7 2.8  56.1 55.2  266  43.7  0.0  0.8  55.3  77.9  0.5  0.7  20.9  44.3  0.0  1.2  54.3  7/25/94  294  46.8  0.0  0.0  53.2  72.4  0.0  0.0  27.6  48.0  0.3  0.0  51.7  8/8/94  308  47.6  0.3  0.0  56.1  0.4  0.0  43.4  42.0  0.0  0.0  57.9  329  38.9  0.4  1.7  52.1 59.0  52.3  0.0  0.0  47.7  41.0  0.0  0.0  59.0  45.7  0.4  0.0  53.9  52.3  0.0  0.0  47.7  43.6  0.0  0.0  56.4  52.1  0.0  0.0  47.9  40.4  0.4  0.0  59.2  8/29/94 9/26/94  357  0.0  54.4  0.4  1.4  62.4  36.0  0.4  1.3  62.2  0.7  2.2  66.7  26.3  0.6  3.4  69.6  0.6  2.5  71.4  18.3  0.4  4.1  77.0  16.8  0.3  0.0  82.8  12.7  0.0  0.0  87.3  6.9  0.7  4.7  87.6  0.5  5.5  88.8  10/17/94  378  45.5  0.0  10/28/94  389  35.6  10/31/94  392  30.3  11/4/94  396  25.5  11/10/94  402  11/14/94  406  11/21/94  413  27.7  0.0  0.0  72.3  18.9  0.9  3.5  76.6  12/23/94  445  14.7  0.7  57.7 53.5  3.3  81.2  50.3  0.0 0.0  0.0 0.0  42.3 46.5  0.5  0.0  49.2  5.1  1/9/95  462  13.1  0.5  0.0  86.4  51.3  0.0  0.0  48.7  4.2  0.6  7.5  87.6  1/16/95  469  17.2  0.4  2.5  79.8  47.6  0.0  0.0  52.4  4.9  1.1  8.8  85.1  1/23/95  476  17.9  0.6  0.0  81.5  37.8  0.4  0.0  61.7  6.4  0.6  6.7  86.3  1/30/95  483  15.9  0.9  3.7  79.5  32.1  0.7  0.0  67.1  5.8  0.7  6.5  87.0  2/13/95  497  13.5  0.9  0.0  85.5  27.7  0.6  11.2  60.5  5.1  0.8  7.4  86.8  82.9  31.2  0.2  18.4  50.2  6.3  1.8  27.1  64.7  2/27/95  511  12.1  1.0  3.9  3/13/95  525  10.1  0.0  4.0  85.8  22.7  0.0  10.9  66.3  3.9  0.9  15.3  79.9  3/27/95  539  11.4  0.7  3.8  84.0  25.0  0.5  0.0  74.4  5.8  1.2  0.0  93.0  4/3/95  546  12.3  0.7  0.0  87.0  25.2  0.0  0.0  74.7  5.8  0.0  8.7  85.5  4/10/95  553  21.3  0.0  0.0  78.6  31.0  0.0  0.0  69.0  15.2  0.0  4.8  79.9  4/17/95  560  0.0  25.7  0.0  0.0  74.3  41.8  0.0  0.0 0.0  60.2  0.0  72.0 66.1  39.8  567  0.0 0.0  0.0  4/24/95  27.9 33.9  58.1  30.9  0.0  0.0  69.1  5/8/95  581  35.2  0.9  0.0  63.8  42.1  0.7  0.0  56.8  35.3  0.6  0.0  64.1  599  41.5  0.0  0.0  58.5  44.5  0.0  0.0  55.5  40.7  0.0  0.0  59.2  0.0  0.0  56.2  43.5  0.0  0.0  56.5  43.5  0.0  0.0  56.5  5/26/95 6/26/95  630  43.8  T f CM T f CO c o CO CO  o  LO LO CO 00 LO T f 00 o o  o  8  IV co co  Tf IV O)  co CM CM c o  in  co oo  CM LO OO  CM 00 Tf Tf  o  | v o o OO o o o o CM c o CO I V oo 00 LO CM i — OO CM CM CO  in  in  oo oo CM L O 00 CO CO CM CM CO T f o o  in o  in  8!8  o o  |v  Tf  co  in  CO CT  s  § ft! 8 iv 8 oo  CT CO  in to  oo  3  00  o  |v  co oo Tf  3  tv  O  co T f CO OO o o  in  rv |v  oo  00 |v  CO 1—  o o  1 1484 1490 I 2093 I 1495 1809 I 2602 I 1644 1696 I 2718 I 1752I 1632 I 2980 I 2327 I 4053 I 2106 I 4260 I 1695 I 1815 I 4568 | 1575 j 2192 I 5257 I 1782 I I 5750 I 1970 I 3034 I 6144 I 2140 I 3296 I 2098 I 3423 I 4632 I 2193 I 4406 I 4138 I 2668 I 4617 I 4542 I 2878 I I 3397 I 4991 5147 I 3752 I 3814 6904 I 2682 I 3528 I 6309 I 1648 I 3190 I 5857 I 1489 | 4519 I 7665 I 2856 I 8785 I 2183 I 4279 4423 I 9044 I 3546 I 4129 I 4216 I 3365 I 4013 I 13700 I 3385 I 4305 I 10169 I 3685 I 3905 I 9469 I 3469 I 4514 I 10232 I 3857 I 4979 I 11964I 4199 I 7241 I 16627 I 5517 I 6268 I 15088 I 4849 I 6080 I 14520 I 4688 I  00  o  1  SS  |v oo 00  oo m 00  in  o in  v  oo  LO  Tf 00  co  oo CO o o  Tf  co  901  o T?  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LO  o  Tf CM IV  v CM co co  1199 1085 1145 I 1312  CO i— Tf CM CM L O T f  I  iv  oo co co | v co CO LO o o LO  1197  CO oo CM ft! oo O  12/6/93 12/13/93 12/20/93 12/27/93  0> CO  17701 18011 11281  o  1027J  CM  13361  CO  12171  11731  Tf  15861  to  19881  co  17141  iv  11101  oo  16051  G.2  IL66  IGas produ Column #1 Date Time(day) 1 23571 10/4/93 10/11/93 15711 10/18/93 10/25/93 12171 21841 11/1/93 2077 12641 11/15/93  Appendix G. Gas Characteristics Data 291  Gas Production  CM 00 CO oo LO V CM c o | v  to  m ft!  s  o  5)  to  o  m  |v |v  CT I V O 00  | v o o CM o 00 to m to m 00 to CO |v  rv 0) Tf CM OO  IV  ft!  00  o in  8  o  oo  oo Tf CM  o o  oo  co  c?  292  Appendix G. Gas Characteristics Data  8  8  s  si  is  3 SI a  5  a  s  8  s 3  S3  a  S3  SI S38  SI  8  8  8  is  Si  a  8 8  8 8  8  8  8 a S3  88  8  SI  a 8  3  a  8  a si  CJ)  s 8  SI  a 8 8!  a3  8 3 Si  3  5  3 8  33 8  5 co Sic. Si  a  8  m in cn CD CD  c. co  

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