Advanced electrochemical oxidation processes have emerged as a promising method for the destruction of persistent organic material in variable waste streams. Although the process has been successfully employed for wastewater treatment applications, high energy requirements, and the risk of formation of undesirable by-products may limit its application in the field of leachate treatment. This study focuses on the investigation of the feasibility of removing organics and ammonia by electrochemical oxidation coupled with ozone, Fenton or lime. Landfill leachate was treated by two different bench scale electrochemical oxidation reactors coupled with ozone oxidation, Fenton coagulation or lime precipitation. The electrochemical oxidation was conducted using a titanium anode coated with multi-metal oxides (MMO) at three-different current densities for different durations. Treatment performance was determined based on the removal of COD, ammonium-N, and turbidity. A three-level factorial design was established, and response surface methodology (RSM) was introduced to determine the optimum process parameters. The results suggest that the process can remove appreciable amounts of ammonium-N and COD in a very short time, demonstrating that the process is effective in rapidly degrading recalcitrant organics in leachate. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Disposing of waste on land has been a method practiced by many countries because it is relatively inexpensive. This has led to the fast increase of landfilling option which is also due to increase of waste generation, resulting in the increase in the urgency of investigating cheap measures of treating wastewater (leachate) that is generated from landfills prior to its discharge to the environment. After the application of the process of nitrification using Sequencing Batch Reactor (SBR) such as is applied at Mariannhill landfill site, Durban, the treated leachate still contains high level of nitrate ranging from 500 – 2000 mg/ℓ, which greatly exceeds the discharge limit of 12 mg/ℓ. Ex-situ bio-denitrification has been used widely around the world in various technological applications (SBRs, anaerobic trickling filters, etc.) that generally employ expensive chemicals. Hence the need to investigate the removal of nitrates using in-situ biodenitrification processes using readily available carbon sources such as fresh commercial garden refuse (CGRraw) and composted commercial garden refuse (CGR10). Both carbon sources were mixed with waste that had been treated for 8 weeks (Cell 1) and 16 weeks (Cell 2). The aim of this study is to determine the viability of pre-treated general waste at different degrees of stability (carbon contents) as carbon sources for in-situ bio-denitrification in landfills. The focus was mainly on determining the suitability, the kinetics and the performance of the different substrate. The suitability of the substrates to perform denitrification was assessed based on the carbon content and carbon to nitrogen ratio in the substrate. On establishing suitability, the kinetic rate of denitrification was assessed for each substrate. The kinetics analysis was based on the time taken for full denitrification to occur and the concentration of the byproducts of the denitrification process such as Ammonia. Characterization tests were performed to determine the suitability of the substrates to be used as carbon sources for denitrification. In situ denitrification processes were simulated at smaller scale in the laboratory using anaerobic batch reactors, with biologically treated leachate and seeded Treated leachate from the Sequencing Batch Reactor. Batch tests were conducted at a nitrate concentration level of 500 mg/ℓ. The combination of 8 weeks treated waste with Fresh Commercial Garden Refuse (Cell 1 + CGRraw) and with Commercial Garden Refuse (Cell 1 + CGR10), respectively, provided the most suitable substrates for denitrification as they contained the highest carbon content as well as relatively high carbon to nitrogen ratio (C:N) . Although the 16 weeks treated waste together mixed with Commercial Garden Refuse (Cell 2 + CGR10) had the lowest C:N ratio, this could be due to a lack of homogeneity within the sample. The results of the batch tests confirms that 8 weeks treated waste (Cell 1) and 16 weeks treated waste (Cell 2) substrates were both too stable and contained too little carbon to attain full denitrification. In addition to the inability to attain full denitrification, Cell 2 leached out nitrate of approximately 500 mg/ℓ NO3-N back into the batch. The batch test results showed that the cells substrates augmented with CGRraw and CGR10 achieved positive results as full denitrification was achieved within a maximum of 7 days for Cell 1 and 14 days for Cell 2. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

Leachate clogging in the Leachate Collection System (LCS) due to chemical precipitations and biofilms produced by microbial activities is a common phenomenon in any Municipal Solid Waste (MSW) landfill. This study focuses on quantifying the factors that impact the micro-environment of leachate; and microbial activities that help the precipitates to form and attach to the LCS. It also evaluates the performance of operational changes that have been implemented or the potential alternatives and recommends the possible measures to reduce the severity of clogging. A field scale side-by-side pipe network, and several laboratory setups were used in this study. Calcite is identified to be the predominant phase present in the precipitates using XRD/XRF analysis which, concur with the previous studies. Microbial growth and activities enhance the precipitation of CaCO3 in LCS. Clogging in LCS pipes can be controlled if not eliminated by continuous monitoring along with frequent cleaning with physiochemical processes. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Waste is commonly disposed in landfills, this result in the formation of leachate which needs to be treated to acceptable standards before being discharged to the environment. High concentrations of pollutants, particularly ammonia, in the landfill leachate are persistent even after the closure of the landfill and it requires ad hoc treatment. Treated leachate can still be characterized by high concentrations of nitrates, which exceeds the discharge standards. This phenomenon is observed in the Mariannhill landfill site in Durban, where leachate is nitrified in a Sequencing batch reactor and produces effluent with over 1000 mg/l (Trois et al, 2010a). Denitrification can be used to remove nitrate concentrations, this process occurs under anoxic conditions in the presence of an external carbon source. Denitrification treatment methods utilize chemicals such as methanol and ethanol as carbon sources, but the large scale application of these chemicals is often uneconomical. This research aims at identifying the cost effective treatment system for bio-denitrification that utilizes commercial garden refuse (CGR raw and lightly composted for 10 weeks “CGR 10”) as carbon sources. The feasibility checks for applying these substrates were based on the efficiency and kinetics of nitrate removal over a short and long-term period, thus providing the estimates for operational procedures. Initial characterization tests, batch and column tests were performed in the lab towards achieving the aim of this research. All batch tests achieved 100% of nitrate removal, but CGR raw was faster than CGR 10 with a time difference of 16% and 20% for batches at 100 and 500 mg/L, respectively. The significant difference in the kinetic removal efficiency was observed in batch tests at 2000 mg/L, where CGR raw was about 18 times faster than CGR 10 and about 2 times faster than that of CGR raw at 500 mg/L. Thus, the kinetics of nitrate removal in CGR raw at 2000 mg/L was suspected to be due to chemical reaction other than biological reaction. In the second set of batch tests the kinetics of nitrate removal for CGR raw was about 3 times that of CGR 10. The column tests, which were operated as continuous flow reactor did not achieve full denitrification due to high flow rate applied. First set of column tests (columns A) used previously used substrates to treat synthetic nitrate solution (500 and 2000 mg/L). Second set of column tests (columns B) used fresh substrates to treat pre-treated landfill leachate with nitrate concentration of about 2000 mg/L. CGR 10 achieved better removal efficiency than CGR raw when treating synthetic solution. Whereas, CGR raw achieved better nitrate removal when treating pre-treated landfill leachate. Decrease in flow rate improved the removal efficiency of the substrates. Dilution of nitrified leachate to about 500 mg/L could improve the efficiency of the substrates. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

Since the United States Environmental Protection Agency (USEPA) began requiring landfills to implement a leachate collection system in 1991, the proper disposal of leachate has become a growing concern. The potential toxicity of landfill leachate will contaminate groundwater and soil if not managed properly. Research has been made in efforts to manage leachate in a cost-effective, single treatment process. Photocatalytic oxidation is an advanced oxidation process (AOP) which has shown ability to reduce toxicity of an array of leachate constituents including organics, inorganics and heavy metals. The purpose of this manuscript is to scale up the batch scale study of TiO2 photocatalytic degradation of leachate utilizing a pilot scale falling film reactor. In this research project, the use of UV/TiO2 for the removal of chemical oxygen demand (COD), ammonia, alkalinity and color will be studied in order to optimize catalyst dosage, determine pH effects and reaction kinetics and develop preliminary cost estimates. / by Frank Youngman. / Thesis (M.S.C.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

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

The objective of this research was to determine if mature landfill leachate could be treated to a level so that it was safe to discharge to the environment. The treatment method was an Advanced Oxidation Process. The process utilized Titanium Dioxide and UV. Three different reactor types were used, falling film, flow through and falling film + Electron Magnetic Oxygen Hydrogen (EMOH). To improve removal pre-treatment with titanium dioxide settling were conducted in conjunction with treatment in a reactor. The best removal was obtained with pre-treatment with titanium dioxide settling, followed by the falling film + EMOH reactor. In 8 hours, removal was 63% for COD, 53% for ammonia, 73% for alkalinity and 98% for calcium hardness. The kinetics found in this experiment show that full treatment times for safe discharge vary between contaminates. For complete removal of all tested contaminates to safe discharge regulations requires 185 hour of treatment. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection