Despite improved liner design, there are still reported incidences of landfill leachate, rich in heavy metals, percolating through to groundwater and threatening ecosystems. This thesis introduces the concept of segregating municipal solid wastes (MSW) according to their major heavy metals and their metal's adsorption compatibility. Each segregated portion can be disposed in a different landfill compartment to minimize leaching of these heavy metals with the greatest bioactive impact. The validity of the concept was evaluated by batch and column retention mobility studies using copper (Cu) alone or with either lead (Pb) or cadmium (Cd) in solutions bearing various pHs. This was supported by selective sequential extraction (SSE) to determine the affinity to specific liner fractions. The following summarizes the procedure used. / Beforehand, a soil column test using sand with 5 and 10% bentonite was conducted to develop an equation predicting liner permeability, k , under simulated field conditions. The column permeability test revealed that a liner with 5% bentonite resulted in a k value which respected the North American criteria of 10-5 m/s. / In the batch experiments, solutions with Cu alone or with Cd or Pb, adjusted to pH of 3.7, 5.5 or 7.5, were applied to sand liners with 0%, 5% or 10% bentonite, having CEC's of 2.0, 6.4, and 10.8 (cmol(+) kg-1 ), respectively. Bentonite, pH and Pb significantly affected Cu adsorption. Cu was adsorbed by the liners at pH <6.5 whereas Cu precipitated at pH >6.5. Cu retention was higher in the presence of Cd than in that of Pb, at all combinations of CEC and pH. Competition between metals was greater in liners with lower CEC and therefore fewer adsorption sites. Limiting Pb in a landfill compartment can improve Cu adsorption at pH's below the precipitating threshold. / In the SSE procedure, the liner samples were centrifuged, decanted from their solutions and each adsorption fraction analyzed for Cu content. Results indicated that the carbonate fraction adsorbed more Cu, and that Pb significantly increased the mobility of Cu due to competition for exchangeable sites. / In the final soil column test using a sand liner with 5% bentonite, the leachate had an initial pH of 3.7. The leaching test confirmed the compatibility of Cu with Cd. The leaching of Cu was greater in the presence of Pb. Total metals in leachate was greater for the Cu-Cd solutions than for the Cu-Pb, because of Cd's relatively high mobility. The sequential extraction results showed again that the carbonate fraction dominated metal adsorption. Total heavy metal leaching followed the order of Cu/Cd > Cu/Pb > Cu alone. / Thus, disposing MSW in landfill compartments based on their heavy metal compatibility can minimize migration of heavy metals.

by Tong Suk Wah. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 196-206). / Abstract --- p.i / Acknowledgments --- p.iv / Table of Contents --- p.v / List of Abbreviations --- p.ix / List of Tables --- p.xi / List of Figures --- p.xv / Chapter 1 --- Introduction / Chapter 1.1 --- Landfilling in Hong Kong --- p.1 / Chapter 1.2 --- Generation of Landfill Leachate --- p.3 / Chapter 1.3 --- Composition of Landfill Leachate --- p.6 / Chapter 1.4 --- Toxicity of Landfill Leachate --- p.12 / Chapter 1.5 --- Treatment of Landfill Leachate --- p.15 / Chapter 1.5.1 --- Physico-chemical treatment --- p.16 / Chapter 1.5.1.1 --- Coagulation/Flocculation/Precipitation --- p.16 / Chapter 1.5.1.2 --- Oxidation --- p.18 / Chapter 1.5.1.3 --- Activated carbon adsorption --- p.19 / Chapter 1.5.1.4 --- Ammonia stripping --- p.20 / Chapter 1.5.1.5 --- Reverse osmosis --- p.21 / Chapter 1.5.2 --- Biological treatment --- p.22 / Chapter 1.5.2.1 --- Aerobic treatment --- p.22 / Chapter 1.5.2.1.1 --- Activated sludge system --- p.23 / Chapter 1.5.2.1.2 --- Aeration lagoon --- p.25 / Chapter 1.5.2.1.3 --- Sequencing batch reactor --- p.26 / Chapter 1.5.2.1.4 --- Trickling filter --- p.27 / Chapter 1.5.2.1.5 --- Rotating biological contactor --- p.27 / Chapter 1.5.2.2 --- Anaerobic treatment --- p.29 / Chapter 1.5.3 --- Co-treatment with municipal wastewater --- p.32 / Chapter 1.5.4 --- Recirculation --- p.33 / Chapter 1.5.5 --- Irrigation --- p.34 / Chapter 1.6 --- Aims of the Thesis --- p.35 / Chapter 2 --- Characterization of Landfill Leachate / Chapter 2.1 --- Introduction --- p.37 / Chapter 2.2 --- Materials and Methods / Chapter 2.2.1 --- Description of landfill sites --- p.39 / Chapter 2.2.2 --- Leachate collection --- p.40 / Chapter 2.2.3 --- Chemical analysis --- p.40 / Chapter 2.2.4 --- Biological analysis --- p.41 / Chapter 2.2.5 --- Statistical analysis --- p.42 / Chapter 2.3 --- Results and Discussion / Chapter 2.3.1 --- Chemical properties of leachate --- p.43 / Chapter 2.3.2 --- Temporal variation of leachate quality --- p.61 / Chapter 2.3.3 --- Correlation of leachate quality and rainfall --- p.65 / Chapter 2.3.4 --- Biological composition of leachate --- p.86 / Chapter 2.4 --- Conclusions --- p.88 / Chapter 3 --- Toxicological Analysis of Landfill Leachate / Chapter 3.1 --- Introduction --- p.92 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Leachate collection --- p.93 / Chapter 3.2.2 --- Chemical analysis --- p.94 / Chapter 3.2.3 --- Biological toxicity testing --- p.94 / Chapter 3.2.3.1 --- Microtox test --- p.95 / Chapter 3.2.3.2 --- Algal bioassay、 --- p.95 / Chapter 3.2.3.3 --- Crustacean bioassay --- p.96 / Chapter 3.2.3.4 --- Fish bioassay --- p.98 / Chapter 3.3 --- Results and Discussion / Chapter 3.3.1 --- Chemical properties of leachate --- p.99 / Chapter 3.3.2 --- Microtox test --- p.105 / Chapter 3.3.3 --- Algal bioassay --- p.108 / Chapter 3.3.4 --- Crustacean bioassay --- p.115 / Chapter 3.3.5 --- Fish bioassay --- p.115 / Chapter 3.4 --- Conclusions --- p.120 / Chapter 4 --- Nitrification of Landfill Leachate / Chapter 4.1 --- Introduction --- p.124 / Chapter 4.2 --- Materials and Methods / Chapter 4.2.1 --- Collection and analysis of leachate --- p.127 / Chapter 4.2.2 --- Set-up of nitrification system --- p.128 / Chapter 4.2.3 --- Experiment 1: Effect of additional phosphate on the rate of nitrification --- p.130 / Chapter 4.2.4 --- Experiment 2: Effect of HRT on the rate of nitrification --- p.130 / Chapter 4.2.5 --- Experiment 3: Effect of additional organic carbon on the rate of nitrification --- p.131 / Chapter 4.2.6 --- Statistical analysis --- p.131 / Chapter 4.3 --- Results and Discussion / Chapter 4.3.1 --- Chemical properties of landfill leachate --- p.132 / Chapter 4.3.2 --- Experiment 1: Effect of additional phosphate on the rate of nitrification --- p.132 / Chapter 4.3.3 --- Experiment 2: Effect of HRT on the rate of nitrification --- p.144 / Chapter 4.3.4 --- Experiment 3: Effect of additional organic carbon on the rate of nitrification --- p.154 / Chapter 4.3.5 --- Inhibition of free ammonia and nitrous acid --- p.162 / Chapter 4.3.6 --- Fate of ammonia --- p.166 / Chapter 4.4 --- Conclusions --- p.170 / Chapter 5 --- Denitrification of Nitrified Leachate / Chapter 5.1 --- Introduction --- p.172 / Chapter 5.2 --- Materials and Methods / Chapter 5.2.1 --- Collection and analysis of landfill leachate --- p.175 / Chapter 5.2.2 --- Set-up of treatment system --- p.176 / Chapter 5.2.3 --- Statistical analysis --- p.178 / Chapter 5.3 --- Results and Discussion / Chapter 5.3.1 --- Performance of nitrification system --- p.178 / Chapter 5.3.2 --- Performance of denitrification system --- p.181 / Chapter 5.3.3 --- Improvement of treatment efficiency --- p.187 / Chapter 5.4 --- Conclusions --- p.190 / Chapter 6 --- General Conclusions --- p.192 / References --- p.196 / Appendices / "Appendix 1 Medium for enumeration of heterotrophic bacteria, fungi, carbohydrate-utilizing bacteria, protein-utilizing bacteria and lipid-utilizing bacteria" --- p.207 / Appendix 2 Preparation of Bristol's medium --- p.210 / Appendix 3 Enumeration of ammonia oxidizers by Most Probable Number Method --- p.211 / Appendix 4 Enumeration of nitrite oxidizers by Most Probable Number Method --- p.214

Tsang Chin-kan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 165-176). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.v / Table of contents --- p.vi / List of tables --- p.ix / List of figures --- p.x / List of plates --- p.xii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Municipal solid waste generation and disposal --- p.1 / Chapter 1.2 --- Land filling --- p.3 / Chapter 1.3 --- Landfill sturcture --- p.6 / Chapter 1.3.1 --- Landfill envelope --- p.6 / Chapter 1.3.2 --- Landfill lining --- p.6 / Chapter 1.3.3 --- Leach ate collection and removal system --- p.9 / Chapter 1.3.4 --- Gas collection and control system --- p.9 / Chapter 1.3.5 --- Final cover system --- p.9 / Chapter 1.4 --- Landfill leach ate generation and characterization --- p.11 / Chapter 1.4.1 --- Landfill stabilization and leachate characteristics --- p.13 / Chapter 1.4.1.1 --- Aerobic phase / Chapter 1.4.1.2 --- Acetogenic phase / Chapter 1.4.1.3 --- Methanogenic phase / Chapter 1.4.2 --- Leachtate characteristic and landfill age --- p.15 / Chapter 1.5 --- Toxicity of landfill leachate --- p.17 / Chapter 1.6 --- Leachate treatment --- p.18 / Chapter 1.6.1 --- Land disposal --- p.19 / Chapter 1.6.1.1 --- Leachate recirculation / Chapter 1.6.1.2 --- Leachate irrigation / Chapter 1.7 --- Landfills in Hong Kong --- p.25 / Chapter 1.7.1 --- Landfill leachate generation in Hong Kong --- p.27 / Chapter 1.8 --- Selection of sampling sites --- p.29 / Chapter 1.9 --- Knowledge gaps --- p.33 / Chapter 1.10 --- Aims of thesis --- p.34 / Chapter 1.11 --- Project outlines --- p.34 / Chapter Chapter 2 --- Species selection for leachate irrigation / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Materials and Methods --- p.36 / Chapter 2.2.1 --- Leachate collection --- p.38 / Chapter 2.2.2 --- Chemical analysis of leachate --- p.38 / Chapter 2.2.3 --- Greenhouse pot experiment --- p.40 / Chapter 2.2.4 --- Plant harvesting and post harvest analysis --- p.43 / Chapter 2.2.4.1 --- Foliar N and P / Chapter 2.2.5 --- Statistical analysis and test endpoints --- p.43 / Chapter 2.3 --- Results and Discussion --- p.43 / Chapter 2.3.1 --- Leachate composition --- p.43 / Chapter 2.3.2 --- Plant growth performance --- p.45 / Chapter 2.3.3 --- Biomass production --- p.54 / Chapter 2.3.4 --- Chlorophyll fluorescence --- p.54 / Chapter 2.3.5 --- Tissue nutrient contents --- p.58 / Chapter 2.3.5.1 --- Foliar N / Chapter 2.3.5.2 --- Foliar P / Chapter 2.3.6 --- Effects on N-fixation --- p.60 / Chapter 2.3.7 --- Factors affecting N-fixation regarding leachate irrigation --- p.63 / Chapter 2.3.7.1 --- Soil mineral N content / Chapter 2.3.7.2 --- Soil acidity / Chapter 2.3.7.3 --- Salinity / Chapter 2.3.7.4 --- Soil aeration / Chapter 2.3.8 --- Species selection --- p.67 / Chapter 2.4 --- Conclusions --- p.68 / Chapter Chapter 3 --- Plant growth response of leachate irrigation on phosphorus-amended soil / Chapter 3.1 --- Introduction --- p.71 / Chapter 3.2 --- Materials and Methods --- p.73 / Chapter 3.2.1 --- Leachate sampling and analysis --- p.73 / Chapter 3.2.2 --- Experimental setup --- p.73 / Chapter 3.2.3 --- Plant and soil sampling --- p.74 / Chapter 3.2.3.1 --- Soil pH and electrical conductivity (EC) / Chapter 3.2.3.2 --- Soil N / Chapter 3.2.3.3 --- Soil P / Chapter 3.2.4 --- Statistical analysis --- p.76 / Chapter 3.3 --- Results and Discussion --- p.76 / Chapter 3.3.1 --- Leachate composition --- p.76 / Chapter 3.3.2 --- Plant growth performance --- p.78 / Chapter 3.3.3 --- Biomass --- p.83 / Chapter 3.3.4 --- Tissue contents --- p.87 / Chapter 3.3.4.1 --- Foliar N / Chapter 3.3.4.2 --- Foliar P / Chapter 3.3.5 --- Soil --- p.91 / Chapter 3.3.5.1 --- pH and electrical conductivity / Chapter 3.3.5.2 --- Soil N / Chapter 3.3.5.3 --- Soil P / Chapter 3.3.5.4 --- Addition of lime and gypsum / Chapter 3.4 --- Conclusions --- p.102 / Chapter Chapter 4 --- Responses in plant growth and soil biology to prolonged landfill leachate irrigation / Chapter 4.1 --- Introduction --- p.105 / Chapter 4.2 --- Materials and Methods --- p.107 / Chapter 4.2.1 --- Leachate sample and collection --- p.107 / Chapter 4.2.2 --- Soil column design --- p.107 / Chapter 4.2.3 --- Plant establishment --- p.107 / Chapter 4.2.4 --- Leachate application --- p.108 / Chapter 4.2.5 --- Soil and plant analysis --- p.108 / Chapter 4.2.5.1 --- Soil texture / Chapter 4.2.5.2 --- SOM / Chapter 4.2.5.3 --- Soil chloride content / Chapter 4.2.6 --- Soil and plant analysis --- p.110 / Chapter 4.2.6.1 --- Dehydrogenase / Chapter 4.2.6.2 --- Phosphatase / Chapter 4.2.6.3 --- Urease / Chapter 4.2.6.4 --- Nitrification / Chapter 4.2.7 --- Percolate --- p.112 / Chapter 4.2.8 --- Statistical analysis --- p.112 / Chapter 4.3 --- Results and Discussion --- p.113 / Chapter 4.3.1 --- Leachate --- p.113 / Chapter 4.3.2 --- Plants --- p.113 / Chapter 4.3.2.1 --- Plant growth / Chapter 4.3.2.2 --- Tissue contents / Chapter 4.3.3 --- Soil --- p.121 / Chapter 4.3.3.1 --- Soil texture / Chapter 4.3.3.2 --- pH and EC / Chapter 4.3.3.3 --- Soil N / Chapter 4.3.3.4 --- Soil P / Chapter 4.3.3.5 --- Soil C1' / Chapter 4.3.3.6 --- SOM / Chapter 4.3.4 --- Soil enzyme and nitrification --- p.132 / Chapter 4.3.4.1 --- Dehydrogenase / Chapter 4.3.4.2 --- Phosphatase / Chapter 4.3.4.3 --- Urease / Chapter 4.3.4.4 --- Nitrification / Chapter 4.3.4.5 --- Correlation analysis / Chapter 4.3.5 --- Percolate --- p.144 / Chapter 4.3.6 --- N balance --- p.150 / Chapter 4.3.7 --- N saturation --- p.153 / Chapter 4.4 --- Conclusions --- p.156 / Chapter Chapter 5 --- General conclusions / Chapter 5.1 --- Summary of findings --- p.158 / Chapter 5.2 --- General considerations regarding leachate irrigation --- p.161 / Chapter 5.3 --- Research prospects --- p.162 / References --- p.165

Wong Shiu Kai Raymond. / Thesis submitted in: July 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 147-157). / Abstracts in English and Chinese. / ABSTRACT --- p.I / ACKNOWLEDGEMENTS --- p.V / TABLE OF CONTENTS --- p.VI / LIST OF ABBREVIATIONS --- p.IX / LIST OF TABLES --- p.X / LIST OF FIGURES --- p.XII / LIST OF PLATES --- p.XVII / Chapter 1. --- INTRODUCTION / Chapter 1.1 --- Landfilling of Solid Wastes --- p.1 / Chapter 1.2 --- Landfilling in Hong Kong --- p.3 / Chapter 1.3 --- Problems of Landfill Leachate --- p.5 / Chapter 1.4 --- Generation of Landfill Leachate --- p.6 / Chapter 1.5 --- Chemical Properties of Landfill Leachate --- p.9 / Chapter 1.6 --- Ecotoxicity of Landfill Leachate --- p.16 / Chapter 1.7 --- Identification of Leachate Toxicity / Chapter 1.7.1 --- Problem of identification of toxicants in landfill leachate --- p.21 / Chapter 1.7.2 --- Toxicity Identification Evaluation --- p.22 / Chapter 1.8 --- Aims of Thesis --- p.27 / Chapter 2. --- CHEMICAL CHARACTERIZATION OF LANDFILL LEACHATE / Chapter 2.1 --- Introduction --- p.30 / Chapter 2.2 --- Materials and Methods / Chapter 2.2.1 --- Site description --- p.33 / Chapter 2.2.2 --- Leachate collection --- p.38 / Chapter 2.2.3 --- Chemical analysis --- p.38 / Chapter 2.2.4 --- Statistical analysis --- p.41 / Chapter 2.3 --- Results and Discussion / Chapter 2.3.1 --- Chemical properties of landfill leachates --- p.41 / Chapter 2.3.2 --- Variation of chemical properties with different ages --- p.53 / Chapter 2.3.3 --- Variation of chemical properties with different season --- p.56 / Chapter 2.3.4 --- Principal Component Analysis --- p.85 / Chapter 2.4 --- Conclusions --- p.91 / Chapter 3. --- ECOTOXICOLOGICAL CHARACTERIZATION OF LANDFILL LEACHATE / Chapter 3.1 --- Introduction --- p.93 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Site description --- p.95 / Chapter 3.2.2 --- Leachate collection --- p.95 / Chapter 3.2.3 --- Toxicity tests --- p.95 / Chapter 3.2.3.1 --- Microtox® test --- p.96 / Chapter 3.2.3.2 --- Protozoan bioassay --- p.97 / Chapter 3.2.3.3 --- Algal bioassay --- p.99 / Chapter 3.2.3.4 --- Crustacean bioassays --- p.102 / Chapter 3.2.3.5 --- Statistical analysis --- p.104 / Chapter 3.3 --- Results and Discussion / Chapter 3.3.1 --- Leachate toxicity --- p.105 / Chapter 3.3.2 --- Sensitivity of tested organisms --- p.110 / Chapter 3.3.3 --- Principal Component Analysis --- p.113 / Chapter 3.3.4 --- Correlation with chemical properties --- p.116 / Chapter 3.4 --- Conclusions --- p.120 / Chapter 4. --- TOXICITY IDENTIFICATION EVALUATION OF MAJOR TOXICANTS IN LANDFILL LEACHATE / Chapter 4.1 --- Introduction --- p.122 / Chapter 4.2 --- Materials and Methods / Chapter 4.2.1 --- Site description --- p.124 / Chapter 4.2.2 --- Toxicity bioassays --- p.124 / Chapter 4.2.3 --- Phase I Toxicity characterization --- p.125 / Chapter 4.2.4 --- Phase II Toxicity identification and multiple manipulations --- p.126 / Chapter 4.2.5 --- Phase III Toxicity confirmation --- p.128 / Chapter 4.3 --- Results and Discussion / Chapter 4.3.1 --- Chemical properties of collected sample --- p.129 / Chapter 4.3.2 --- Phase I results --- p.130 / Chapter 4.3.3 --- Phase II results --- p.132 / Chapter 4.3.4 --- Phase III results --- p.138 / Chapter 4.3.5 --- Use of TIE in leachate monitoring --- p.139 / Chapter 4.4 --- Conclusions --- p.140 / Chapter 5. --- OVERALL CONCLUSIONS --- p.142 / REFERENCES --- p.147

by Leung Chi Kam Joseph. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985 / Bibliography: leaves 178-198

Cheng Chung-yin. / Thesis submitted in: December 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 185-195). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.vi / Table of contents --- p.viii / List of tables --- p.xi / List of figures --- p.xii / List of plates --- p.xiv / Plant species used in the experiments --- p.xv / Chapter 1 Introduction / Chapter 1.1 --- Soil wastes as an environmental challenge --- p.1 / Chapter 1.2 --- Landfilling --- p.1 / Chapter 1.2.1 --- Waste degradation --- p.4 / Chapter 1.2.2 --- Control of degradation by-products --- p.6 / Chapter 1.3 --- Landfill leach ate --- p.8 / Chapter 1.3.1 --- Generation and control of landfill leachate --- p.8 / Chapter 1.3.2 --- Leachate characterization --- p.10 / Chapter 1.3.3 --- Leachate from local landfills --- p.15 / Chapter 1.3.4 --- Leachate treatment --- p.15 / Chapter 1.4 --- Leachate irrigation --- p.16 / Chapter 1.4.1 --- Common practices of wastewater irrigation --- p.17 / Chapter 1.4.1.1 --- Spray irrigation / Chapter 1.4.1.2 --- Rapid infiltration / Chapter 1.4.1.3 --- Overland flow / Chapter 1.4.2 --- Effects of leachate irrigation --- p.19 / Chapter 1.4.2.1 --- Effect of leachate irrigation on soil percolate / Chapter 1.4.2.2 --- Effect of leachate irrigation on soil / Chapter 1.4.2.3 --- Effect of leachate irrigation on plants / Chapter 1.5 --- Landfilling in Hong Kong --- p.24 / Chapter 1.5.1 --- Climate --- p.24 / Chapter 1.5.2 --- Geography and economy --- p.25 / Chapter 1.5.3 --- Waste composition --- p.25 / Chapter 1.5.4 --- Leachate sampling sites --- p.27 / Chapter 1.6 --- Objectives of this study --- p.30 / Chapter 1.6.1 --- Knowledge gaps --- p.30 / Chapter 1.6.2 --- Project outline --- p.33 / Chapter Chapter 2 --- Phytotoxicity evaluation of landfill leachate using seed germination tests / Chapter 2.1 --- Introduction --- p.34 / Chapter 2.1.1 --- Tests involving the use of germinating seeds --- p.34 / Chapter 2.1.2 --- Importance of germination to plants --- p.34 / Chapter 2.1.3 --- Advantages of germination tests --- p.35 / Chapter 2.1.4 --- Limitations of using germination as an endpoint --- p.35 / Chapter 2.1.5 --- Methods of germination test --- p.36 / Chapter 2.1.5.1 --- Test design / Chapter 2.1.5.2 --- Plant species / Chapter 2.1.5.3 --- Measurement endpoints / Chapter 2.1.5.4 --- Statistical analysis and test endpoints / Chapter 2.2 --- Objectives of study --- p.41 / Chapter 2.3 --- Materials and methods --- p.42 / Chapter 2.3.1 --- Sample collection --- p.42 / Chapter 2.3.2 --- Chemical analysis --- p.42 / Chapter 2.3.3 --- Statistical analysis --- p.43 / Chapter 2.3.4 --- Phytotoxicity assay --- p.43 / Chapter 2.4 --- Results and discussion --- p.44 / Chapter 2.4.1 --- Leachate characterization --- p.44 / Chapter 2.4.1.1 --- Comparison among landfill sites / Chapter 2.4.2 --- Phytotoxicity assay --- p.51 / Chapter 2.4.2.1 --- Dose response relationships / Chapter 2.4.2.2 --- Implication of hormetic-like response on the selection of statistical model / Chapter 2.4.2.3 --- Phytotoxicity of leachate samples / Chapter 2.4.2.4 --- Comparison between species / Chapter 2.5 --- Conclusions --- p.65 / Chapter Chapter 3 --- Leachate irrigation: Effects on plant performance and soil properties / Chapter 3.1 --- Introduction --- p.67 / Chapter 3.2 --- Materials and methods --- p.70 / Chapter 3.2.1 --- Leachate sampling and analysis --- p.70 / Chapter 3.2.2 --- Leachate irrigation experiment --- p.71 / Chapter 3.2.3 --- Soil and plant analysis --- p.73 / Chapter 3.2.3.1 --- Soil sampling and preparation / Chapter 3.2.3.2 --- Soil texture / Chapter 3.2.3.3 --- pH and electrical conductivity / Chapter 3.2.3.4 --- Organic carbon / Chapter 3.2.3.5 --- Nitrogen / Chapter 3.2.3.6 --- Phosphorus / Chapter 3.2.3.7 --- Chloride / Chapter 3.2.3.8 --- Metals / Chapter 3.2.3.9 --- Foliage analysis / Chapter 3.3 --- Results and discussion --- p.75 / Chapter 3.3.1 --- Leachate --- p.75 / Chapter 3.3.1.1 --- Chemical properties / Chapter 3.3.1.2 --- Phytotoxicity / Chapter 3.3.2 --- Plant responses --- p.79 / Chapter 3.3.2.1 --- Growth / Chapter 3.3.2.2 --- Plant survival and health / Chapter 3.3.2.3 --- Tissue contents / Chapter 3.3.2.4 --- Incorporating the results of germination tests in leachate irrigation practice / Chapter 3.3.3 --- Soil --- p.101 / Chapter 3.3.3.1 --- Initial properties / Chapter 3.3.3.2 --- Soil reaction (pH) / Chapter 3.3.3.3 --- Nitrogen / Chapter 3.3.3.4 --- Phosphorus / Chapter 3.3.3.5 --- Conductivity / Chapter 3.3.3.6 --- Chloride / Chapter 3.3.3.7 --- Metals / Chapter 3.4 --- Conclusions --- p.119 / Chapter Chapter 4 --- Fate and distribution of N after soil application of landfill leachate / Chapter 4.1 --- Introduction --- p.121 / Chapter 4.1.1 --- The needs of external N supply in ecological restoration --- p.121 / Chapter 4.1.2 --- Objectives of study --- p.122 / Chapter 4.2 --- Materials and methods --- p.123 / Chapter 4.2.1 --- Leachate --- p.124 / Chapter 4.2.2 --- Soil column --- p.124 / Chapter 4.2.3 --- Plant selection and establishment --- p.127 / Chapter 4.2.3 --- Leachate application --- p.129 / Chapter 4.2.4 --- Post irrigation harvesting and analysis --- p.130 / Chapter 4.3 --- Results and discussion --- p.130 / Chapter 4.3.1 --- Leachate --- p.130 / Chapter 4.3.2 --- Plants --- p.132 / Chapter 4.3.2.1 --- Growth / Chapter 4.3.2.2 --- Tissue N contents / Chapter 4.3.3 --- Soil and soil percolate --- p.139 / Chapter 4.3.3.1 --- Percolate volume and soil moisture / Chapter 4.3.3.2 --- pH / Chapter 4.3.3.3 --- Electrical conductivity / Chapter 4.3.3.4 --- Nitrate / Chapter 4.3.3.5 --- Ammonium / Chapter 4.3.4 --- N balance of the soil-plant system --- p.160 / Chapter 4.3.4.1 --- Change in the N capital after leachate irrigation / Chapter 4.3.4.2 --- Leaching loss / Chapter 4.3.4.3 --- Unaccountable N loss / Chapter 4.4 --- Conclusions --- p.174 / Chapter Chapter 5 --- General conclusion / Chapter 5.1 --- Summary of findings --- p.176 / Chapter 5.2 --- Ecological consequence of increased and excess N deposition --- p.179 / Chapter 5.3 --- Research prospects --- p.182 / References --- p.185

Thesis submitted in fulfilment of the requirements for the degree of Master of Technology: Chemistry in the Faculty of Applied Sciences at the Cape Peninsula University of Technology, 2012 / Batch experiments were conducted to assess the removal of Ni(II) from aqueous solutions and landfill leachates using low cost adsorbents eggplant peel (EGP), sweet potato peel (SWP) and banana peel (BNP). Preliminary studies were carried out to optimize biosorbent mass, pH, Ni(II) concentration, temperature and contact time for Ni(II) removal. The optimized conditions were then applied to landfill leachates using the selected low cost adsorbents. Ni(II) removal efficiency for each biosorbent was investigated for each parameter. Results indicated that biosorbents masses, pH, initial concentration as well as solution temperature were important factors influencing Ni(II) removal from aqueous solutions. Percentage Ni(II) removal was 66±0.30, 38±3.97 and 33±1.20 using EGP, SWP and BNP, respectively. Ni(II) removal efficiency increased significantly (P ≤ 0.05) with increasing biosorbent mass, pH and Ni(II) initial concentration while it decreased significantly (P ≤ 0.05) with increasing temperature. Although Ni(II) removal efficiency varied significantly with time and the biosorbents no significant (P 0.05) difference was observed between the time interval whether the experiment was conducted in batch or semi batch mode. Results of FTIR studies indicated that several binding and chelating functional groups such as carboxyl, carbonyl and hydroxyl groups on the biomaterials surfaces could be responsible for Ni(II) biosorption. The optimum biosorbent mass for EGP and SWP was 0.4 g and for BNP was 0.05 g. The values for initial concentration, pH, temperature and contact time were 100 mg/L, 5, 22oC and 2 hours, respectively. Ni(II) removal efficiencies using EGP, SWP and BNP were 66, 38 and 33%, respectively. Taking into account the result and optimum condition obtained on Ni(II) removal efficiency from aqueous solution using EGP, SWP and BNP, the Ni(II) removal efficiency using these biosorbents from landfill leachate was investigated. It was found to be significantly (P ≤ 0.05) lower than what was found from aqueous solution.

published_or_final_version / Botany / Master / Master of Philosophy

The purpose of this study was to investigate the effects of copper on the treatment of an abandoned landfill leachate by a Modified Ludzack Ettinger (MLE) single-sludge, activated sludge treatment system. MLE systems are designed to accomplish nitrification and denitrification, and at least two systems were used: one to which copper was added, and one maintained as a control. The system that did not receive copper additions gave an indication of the treatability of the leachate by an MLE system. Copper was added at concentrations of 1.0, 2.0, 2.5, and 5.0 mgCu/L in the influent and the sludge age was varied from 8 to 30 day. It was determined that copper did inhibit nitrification and denitrification. A strong linear relationship was shown to exist between the specific copper loading on the system, that is the total copper entering the system within a day divided by the total biomass within the system, and the soluble copper concentration within the system. The adsorption of copper by the activated sludge, and the resulting soluble copper concentration in the mixed liquor, could be generally described by the Freundlich Isotherm. Intermittent inhibition of nitrification unrelated to copper addition also occurred during treatment of the landfill leachate which was obtained from the abandoned Dixie Caverns Landfill near Roanoke, Virginia. The inhibiting substance was not identified during this study. It did not significantly inhibit denitrification, but did cause elevated effluent suspended solids concentrations. An additional treatment step would be needed for reliable treatment of the leachate. Copper additions caused inhibition of both nitrification and denitrification. The degree of nitrification and denitrification inhibition was a strong function of the soluble copper to ML VSS ratio in the reactors, i.e., the toxin -to -microorganism (TIM) ratio. Nitrification and denitrification appeared to be equally sensitive to copper. Both were severely inhibited at a soluble copper to ML VSS ratio of 0.001 in aerobic and anoxic reactors, respectively. Nitrosomonas species were more strongly inhibited by copper concentrations than were the Nitrobacter species. The denitrifiers appeared to be as sensitive to copper as the Nitrosomonas species. / Master of Science

A landfill is in a reserved space on land used for the disposal of refuse by utilizing the principles of engineering to confine the refuse to the smallest practical area to prevent the creation of nuisances to public health or safety (Andersen et al. 1967). However, because landfills are open to the atmosphere, rainfall can saturate them, resulting in a liquid called leachate. Leachate generated within the landfill contains suspended solids, soluble components of the waste and by-products from the degradation of the waste by various micro-organisms. Treatment of leachate is an emerging area of need. In this manuscript the main purpose is to investigate a laboratory scale batch reactor that is able to detoxify and treat leachate by using an advanced oxidation process (i.e. TiO2). Based on the results obtained from this ground breaking research, it appears that the process investigate has the potential to radically change the way landfill leachate is treated. Scale up may provide direction that can be used to improve the efficiency of the different stages of toxicity of leachate during the entire life of a landfill. / by Andrâe McBarnette. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.