Landfill leachate is considered as a complex wastewater with various organic and inorganic species which must meet strict discharge standards before its release. Due to such high concentration of diverse pollutants, leachate is low in biodegradation; therefore, a proper usage of physicochemical treatments is required. In this study, membrane distillation (MD) has been used along with Fenton treatment process for pre-coagulation to achieve an effective removal of contaminants. MD is a technology derived with vapor pressure difference across the hydrophobic membrane which traps the feed-wastewater vapor at the entrance of the hydrophobic side before permeation. In order to modify and assist in membrane technology's common drawback, which is dealing with foulants, Fenton oxidation is coupled in the leachate treatment process. Fenton is reserved to be the most effective for leachate treatment and is widely used due to its simple operation and low costs. Fenton oxidation was able to lessen the chemical oxygen demand (COD) concentration of leachate up to 55% while increasing the conductivity and reducing the concentration of NH4-N. The membrane flux and volume had a significant increase with a use of lower COD leachate after Fenton treatment coupled with MD. / Master of Science / Landfilling has been recognized as a principal disposal process of municipal solid wastes globally over the past decades, and this disposal method has been one of the leading concerns for a continuous production of landfill leachate. Leachate is considered as a complex wastewater with a variety of organic and inorganic species which must meet strict discharge standards before its release. Due to such high concentration of diverse pollutants, leachate is low in biodegradation; therefore, a proper usage of physicochemical treatments is required. In this study, membrane distillation (MD) has been used along with Fenton treatment process for pre-coagulation to achieve an effective removal of contaminants. MD is a technology derived with vapor pressure difference across the hydrophobic membrane which traps the feed-wastewater vapor at the entrance of the hydrophobic side before permeation. MD has several advantages which include reduced operating temperature compared to conventional distillation processes, fewer requirements of membrane cleaning, and lower operating hydraulic pressure than other conventional pressure-driven membrane processes such as reverse osmosis (RO). This technology has a common drawback along with other membrane-required technologies which is dealing with foulants. For a reduction in membrane fouling, Fenton oxidation is coupled in the leachate treatment process. Fenton is reserved to be the most effective for leachate treatment and is widely used due to its simple operation and low costs.

Landfill leachate contains valuable, recoverable organics, water, and nutrients. This project investigated leachate treatment and resource recovery from landfill leachates by innovative methods such as forward osmosis (FO), bioelectrochemical systems (BES), and advanced oxidation. In this study, a microbial fuel cell (MFC) removed 50-75% of the ammonia from a leachate through the electricity driven movement of ammonium to the cathode chamber followed by air stripping at high pH (> 9). During this process, the MFC system removed 53-64% of the COD, producing a net energy of 0.123 kWh m-3. Similarly, an integrated microbial desalination cell (MDC) in an FO system recovered 11-64% of the ammonia from a leachate; this was affected by current generation and hydraulic retention time in the desalination chamber. The MDC-FO system recovered 51.5% of the water from a raw leachate. This increased to 83.5% when the FO concentrate was desalinated in the MDC and then recirculated through the FO unit. In addition, the project investigated humic acid (HA) recovery from leachate during the synergistic incorporation of FO, HA recovery, and Fenton's oxidation to enhance leachate treatment and to reduce Fenton's reagent requirements. This led to the investigation of harmful disinfection byproducts (DBPs) formation during Fenton's oxidation of landfill leachate. The removal of leachate UV-quenching substances (humic, fulvic, and hydrophilic acids) using an MFC and a chemical oxidant (i.e., sodium percarbonate) with a focus on energy production and cost efficiency were also studied. BES treatment can reduce leachate organics concentrations; lower UV absorbance; recover ammonia; and, in combination with FO, recover water. Although BES is promising, significant work is needed before its use in landfill leachate becomes practical. FO application to leachate treatment must consider the choice of an appropriate draw solute, which should require minimal effort for regeneration. Resources like HA in leachate deserve more attention. Further efforts can focus on purification and application of the recovered products. The emerging issue of DBP formation in leachate treatment also requires attention due to the potential environmental and human health effects. The broader impact of this study is the societal benefit from more sustainable and cost-efficient leachate treatment. / Doctor of Philosophy / On average, each of us produces 3 – 4 pounds of solid waste every day. In the U.S., the yearly generation of solid waste is 250 million tons, while the global generation is 1.1 billion tons. The global management cost of solid waste is around 200 billion dollars. About half of U.S. municipal solid waste ends up in landfills, in China, this number is 80%. Among the different municipal solid waste (MSW) management approaches, landfilling is the most common because of its low cost and relatively low maintenance requirements. In a landfill, the combination of precipitation and solid waste degradation produce leachate, a complex wastewater. A ton of municipal solid waste can generate 0.05–0.2 tons of leachate in its lifetime during the process of landfilling. Leachate contains a vast array of pollutants, which can result in major environmental impact and adverse human health risk if not contained and treated appropriately. At present, leachate is mostly treated biologically, without any resource recovery. Among the myriad recoverable resources in landfill leachates, water and ammonia are the most abundant. We applied innovative approaches such as, bioelectrochemical systems, forward osmosis, advanced oxidation to recover resources and remove contaminants from leachate simultaneously. We also incorporated these novel technologies to help each other. For instance, we recovered humic fertilizer from leachate prior to advanced oxidation (i.e., Fenton’s oxidation) that helped the reduction of Fenton’s reagent requirements. The next step of our study could be the pilot scale application of the proposed techniques so that it can be applied in field. The broader impacts of this study include improvements in sustainability and cost efficiency of leachate treatment that can benefit the society.