The rate of anaerobic digestion (AD) often depends on the rate-limiting hydrolysis step that makes organics available to microorganisms. To achieve efficient conversion of particulates to soluble materials and finally methane, the biomass in the digester must be provided with optimal operational conditions that will allow for biomass retention and substrate metabolism. Two approaches were employed in this study to improve the ultimate biodegradability of waste activated sludge (WAS) - Pre-treatment (PT) and operation using an Anaerobic Membrane Bioreactor (AnMBR). PT of WAS is one way of speeding up hydrolysis. It has been proposed that PT leads to the lysis of cells, which in turn causes the release and solubilisation, and thus availability of intracellular matter to microorganisms for microbial growth and metabolic activities. This study compared the effect of thermal, sonication, and sonication + hydrogen peroxide PT on chemical oxygen demand (COD) solubilisation of WAS. Based on the soluble COD (SCOD) release, it was concluded that combined chemi-sonic treatment resulted in better WAS degradation rather than individual ultrasonic pre-treatment and thermal PT. The highest solubilisation rate was observed at a chemi-sonic PT of 50gH2O2/kgTS and sonication duration of 60 minutes. At this PT, a COD solubilisation of 40% was observed which was significantly different than PT involving only sonication and no pre-treatment (0.88%) at 95% confidence. Therefore a peroxide-sonic PT was chosen to treat WAS in this study as it was expected to result in the greatest improvement in WAS biodegradability. In addition to PT, biodegradability of WAS can also be improved by coupling PT with an AnMBR. AnMBRs prevent biomass washout by decoupling the solids retention time (SRT) from the hydraulic retention time (HRT). Thus, a long SRT can be used to provide sufficient duration for biological activities without increasing the volume of the reactor. In this study, a 4.5L AnMBR with an HRT and SRT of 3 and 20 days, respectively was used to treat raw and PT WAS. In order to compare the biodegradability of PT and raw WAS, the AnMBR was operated in three phases. Phase 1 was operated with raw WAS, Phase 2 was operated with WAS pre-treated with 50 gH2O2/kgTS and 20 minutes ultrasound (US), and Phase 3 was operated with WAS pre-treated with 50 gH2O2/kgTS and 60 minutes US. The anaerobic biodegradability of WAS following a combination of ultrasonic pre-treatment and H2O2 addition was significantly improved, with Phase 3 resulting in the greatest improvement. The COD destruction for phases 1, 2, and 3 were 49%, 58%, and 63%, respectively whereas the volatile suspended solids (VSS) destruction for phases 1, 2, and 3 were 46%, 71%, and 77% respectively. Organic Nitrogen (Org-N) destruction increased from 44% to 52% for phases 1 and 2 respectively. A further increase of 18% in Org-N destruction was observed in phase 3. This improvement in biodegradability of WAS was attributed to the high solubilisations of COD, VSS, and ON and conversion of non-biodegradable materials to biodegradable fractions. In order to determine the effect of PT of WAS on membrane performance, the transmembrane pressure (TMP) and fouling rate were monitored throughout the operation of the AnMBR. Negligible variation in membrane performance was observed over all three phases. At a constant low flux of 2.75 litres/m2/hour (LMH), the TMP and the fouling rate remained low over the course of operation. In order to maintain the performance of the membrane, maintenance cleaning with 50 ml of 2g/L critic acid solution followed by 50 ml of 0.2 g/L sodium hypochlorite was performed three times a week. In addition, a gas sparing rate of 2 L/minute and a permeation cycle of 10 minutes with 8 minutes of operation followed by 2 minutes of relaxation was employed. During phase 2 of this study, a new membrane was installed due to a faulty gas sparging pump. A slight decrease of TMP was observed with the installation of the new membrane; however the decrease was minimal. In addition critical flux for phases 2 and 3 were determined to be in the range of 6 to 12 LMH. In conclusion, the incorporation of H2O2-US PT with AD could allow treatment plants to substantially reduce the mass flow of solids and organics and thus result in a decrease in requirements for downstream sludge processing. With sufficient maintenance, steady operation could be achieved for a hollow fibre AnMBR with a total solids concentration range of 20-25 g/L, an HRT of 3 days, and an SRT of 20 days. It was found that PT could be successfully integrated with AnMBR to substantially reduce the HRT required for digestion when compared to conventional designs.

Anaerobic membrane bioreactor (AnMBR) serves as a more sustainable form of wastewater treatment. However, biofouling is particularly detrimental to the performanceof AnMBRs. This dissertation focuses on understanding more about the biofouling in nMBR, and to devise strategies to control or make use of these biofoulant layers. First, we aim to investigate the microbial community structure of sludge and biofilm from 13 different AnMBRs. Our findings indicate 20 sludge core genera and 12 biofilm core genera (occurrence ≥ 90% samples) could potentially account for the AnMBR performance. Sloan neutral model analysis indicates the anaerobic microbial consortium between sludge and biofilm is largely affected by stochastic dispersal and migration processes (i.e., neutral assembly), suggesting that the majority of these core genera are not selectively enriched for biofilm formation. Therefore, the second part of this dissertation aims to minimize the growth of the overall bacterial cells attached on the membranes. For this, membranes embedded with zinc oxide (ZnO) and copper oxide (CuO) nanoparticles were examined for their antifouling efficacies. Our findings indicate both CuO and ZnO nanoparticles embedded membranes could delay biofouling formation without significantly triggering the overall expression/abundance of antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) in biofilm. Furthermore, CuO and ZnO nanoparticles could inhibit the expression of quorum sensing associated genes, resulting in lower quorum sensing signal molecules production. Despite the positive results demonstrated from this study as well as those from others, we recognize that no control strategies are likely to achieve total prevention of anaerobic biofouling. Therefore, the last part of this dissertation focuses on exploring the effects of different foulant layers on antibiotic-resistant bacteria (ARB) and ARGs removal. Our findings suggest both ARB and ARGs could be absorbed by membrane foulant. Transmembrane pressures and the foulant layer synergistically affected ARB removal, but the foulant layer is the main factor that contributed to ARG removal through adsorption. Overall, the collective findings could bring new insights to the anaerobic membrane biofouling phenomenon, and offer pragmatic approaches to minimize biofouling without compromising the post-AnMBR effluent quality.

Anaerobic membrane bioreactors may provide a sustainable technological solution for digestion of waste activated sludge due to their capacity to achieve substantial volatile solids (VS) destruction and positive energy balances with reduced digester volumes. However, membrane integrated anaerobic systems may have limitations that are imposed by membrane fouling and a decrease in biomass activity due to possible exposure of biomass to high shear conditions. This study characterised bioprocess and membrane performance under varying conditions, identified foulant type and origin and mechanism of fouling, and developed fouling control strategies by using low cross flow velocity and pressure anaerobic membrane systems. The study employed a pilot scale anaerobic digester integrated with negative and neutral tubular membranes; pilot and bench scale control digesters supported with bench scale filtration unit parametric studies. The membranes were polyvinylidene difluoride based with an average pore size of 0.02 micron and were operated at a constant cross flow velocity of 1 ms-1 and constant trans-membrane pressure of 30 kPa. Four operating conditions consisting of different combinations of HRT and SRT were evaluated. By integrating membranes into the digesters it was possible to simultaneously enhance digestion and increase throughput of the digesters without affecting its performance. The anaerobic membrane digester showed 48-49% volatile solids destruction at 30 days SRT under conventional and higher loadings of 1.2±0.4 and 2.1±0.6 kg COD m-3day-1. This was a 100% increase in performance compared to a control digester subjected to higher loading. This result was supported by the associated specific methane generation. The control digesters operated at a relatively higher SRT showed comparable VS destruction and gas generation to the anaerobic membrane running at a similar SRT. However the extra gas generated didn’t compensate heat required to maintain larger volume of the digester. In case of anaerobic membrane digesters due to the high rate feeding, increase biogas production and co-thickening, the energy balance increased by 144 and 200% under conventional and higher loading conditions respectively. Characterization of membrane performance showed that the average sustainable flux was 23.2±0.4 and 14.8±0.4 LMH during HRT-SRTs of 15-30 and 7-15 days respectively. The critical fluxes were in the range of 30-40, 16-17 and 20-22 LM-2H-1 during HRT-SRTs of 15-30, 7-30 and 7-15 days respectively. The decline in membrane performance at a higher loading was associated with the formation of cake layers on the membrane surface that led to reversible fouling. The additional decline in performance at extended SRT was attributed to irreversible fouling. The colloidal fraction of the sludge showed an overall higher fouling propensity during the long term pilot studies and short term filtration tests. The suspended solids fraction of the sludge showed a positive impact at concentration below 15 g/L but resulted in a decrease of membrane performance at higher concentrations. Further studies of foulant origin through a series of microscopic, membrane cleaning and sludge characterization studies showed that the colloidal proteins, soluble carbohydrates and inorganic materials such as iron, calcium and sulfur and their interaction to have a significant impact on membrane fouling. To control anaerobic membrane fouling by the digested sludge, integration of membrane relaxation techniques in the filtration cycle were found effective. By incorporating a unique relaxation technique to tubular membranes, it was possible to increase the sustainable flux to 29.2±1.8 and 34.5±2.5 LM-2H-1 for neutral and negative membranes during 15-30 HRT-SRT process condition. Addition of cationic polymers and sequential mechanical-citric acid membrane cleaning, that targeted both reversible and irreversible fouling was also found effective.

Anaerobic membrane bioreactors may provide a sustainable technological solution for digestion of waste activated sludge due to their capacity to achieve substantial volatile solids (VS) destruction and positive energy balances with reduced digester volumes. However, membrane integrated anaerobic systems may have limitations that are imposed by membrane fouling and a decrease in biomass activity due to possible exposure of biomass to high shear conditions. This study characterised bioprocess and membrane performance under varying conditions, identified foulant type and origin and mechanism of fouling, and developed fouling control strategies by using low cross flow velocity and pressure anaerobic membrane systems. The study employed a pilot scale anaerobic digester integrated with negative and neutral tubular membranes; pilot and bench scale control digesters supported with bench scale filtration unit parametric studies. The membranes were polyvinylidene difluoride based with an average pore size of 0.02 micron and were operated at a constant cross flow velocity of 1 ms-1 and constant trans-membrane pressure of 30 kPa. Four operating conditions consisting of different combinations of HRT and SRT were evaluated. By integrating membranes into the digesters it was possible to simultaneously enhance digestion and increase throughput of the digesters without affecting its performance. The anaerobic membrane digester showed 48-49% volatile solids destruction at 30 days SRT under conventional and higher loadings of 1.2±0.4 and 2.1±0.6 kg COD m-3day-1. This was a 100% increase in performance compared to a control digester subjected to higher loading. This result was supported by the associated specific methane generation. The control digesters operated at a relatively higher SRT showed comparable VS destruction and gas generation to the anaerobic membrane running at a similar SRT. However the extra gas generated didn’t compensate heat required to maintain larger volume of the digester. In case of anaerobic membrane digesters due to the high rate feeding, increase biogas production and co-thickening, the energy balance increased by 144 and 200% under conventional and higher loading conditions respectively. Characterization of membrane performance showed that the average sustainable flux was 23.2±0.4 and 14.8±0.4 LMH during HRT-SRTs of 15-30 and 7-15 days respectively. The critical fluxes were in the range of 30-40, 16-17 and 20-22 LM-2H-1 during HRT-SRTs of 15-30, 7-30 and 7-15 days respectively. The decline in membrane performance at a higher loading was associated with the formation of cake layers on the membrane surface that led to reversible fouling. The additional decline in performance at extended SRT was attributed to irreversible fouling. The colloidal fraction of the sludge showed an overall higher fouling propensity during the long term pilot studies and short term filtration tests. The suspended solids fraction of the sludge showed a positive impact at concentration below 15 g/L but resulted in a decrease of membrane performance at higher concentrations. Further studies of foulant origin through a series of microscopic, membrane cleaning and sludge characterization studies showed that the colloidal proteins, soluble carbohydrates and inorganic materials such as iron, calcium and sulfur and their interaction to have a significant impact on membrane fouling. To control anaerobic membrane fouling by the digested sludge, integration of membrane relaxation techniques in the filtration cycle were found effective. By incorporating a unique relaxation technique to tubular membranes, it was possible to increase the sustainable flux to 29.2±1.8 and 34.5±2.5 LM-2H-1 for neutral and negative membranes during 15-30 HRT-SRT process condition. Addition of cationic polymers and sequential mechanical-citric acid membrane cleaning, that targeted both reversible and irreversible fouling was also found effective.

<p>This master's theses was carried out on assignment from Stockholm Vatten AB as a part of a project developing new waste water treatment techniques. The goal of the theisis has been to evaluate an anaerobic membrane bioreactor for treatment of waste water from Hammarby Sjöstad. The bioreactor has not been heated and the main interest has been to study the gas production, power consumption and the reduction of organic matter and nutrients.</p><p>The system has been completed with a reverse osmosis unit and a total of four batch runs have been made with good results. The use of reverse osmosis allows nutrient in the waste water to be reintroduced into circulation as the reverse osmosis concentrate can be used as crop nutrient.</p><p>The membrane unit is of VSEP ("Vibratory Shear Enhanced Processing") type and an extensive membrane test has been conducted. This so called L-test helped determine the most suitable type of membrane for the system to allow a higher ±ux and thus lower power consumption. The L-test gave good results and a new membrane with a poresize diameter of 0,45 μm was used.</p><p>The organic load on the bioreactor has been more or less constant, around 0,7 kg COD/day, during the seven weeks of testing. The reduction over the entire system including reverse osmosis has been large, around 99 % regarding organic matter and phosporus and 93 % for nitrogen, making the system suitable for waste water treatment except for high power consumption, around 2 kWh/m3. The production of methanegas has worked although it has been quite low, with average values of 0,13 m3 CH4/kg reduced COD.</p> / <p>Examensarbetet är utfört på uppdrag av Stockholm Vatten AB som en del av det pilotprojekt som utvärderar nya tekniker för avloppsvattenrening för Hammarby Sjöstad. Målsättningen med studien har varit att utvärdera ett system bestående av en anaerob membranbioreaktor för behandling av avloppsvatten från Hammarby Sjöstad. Bioreaktorn har inte varit uppvärmd och det som har studerats är reningseffekten, biogasproduktionen samt energiåtgången.</p><p>Systemet har även innefattat en omvänd osmosanläggning och totalt har fyra försök med denna gjorts med goda resultat. Analyser har koncentrerats till att utvärdera reduktion av organiskt material över membranbioreaktorn och av närsalter och metaller över omvänd osmos anläggningen. Bakgrunden till att använda omvänd osmos är att öka återföringen av näringsämnen från avloppsvatten. Resultatet av försöken med omvänd osmos gav ett koncentrat med högt näringsinnehåll och låg halt av tungmetaller vilket ger möjligheten att sprida det på åkermark.</p><p>Membranenheten är av typen VSEP ("Vibratory Shear Enhanced Processing") och ett membrantest har även utfötts för att finna det membran som passar systemet bäst med avseende på flöde och energiförbrukning. Det så kallade L-testet var omfattande och gav en klar bild över vad som skulle vara det bästa membranet. Det membran som visade sig passa systemet bäst var ett membran med en porstorlek på 0,45 μm. Belastningen av organiskt material på reaktorn under försöksperiodens sju veckor har varit mer eller mindre konstant och låg, cirka 0,7 kg COD/dygn. Reduktionen över hela systemet inklusive omvänd osmosanläggningen med avseende på organiskt material och fosfor har varit mycket hög, omkring 99 %. Reduktionen av kväve var som högst 93 %. Gasproduktionen har fungerat och har i genomsnitt varit omkring 0,13 m3 CH4/kg reducerad COD.</p><p>Energiförbrukningen för systemet i motsvarande fullskala blev omkring 2 kwh/m3.</p>

This master's theses was carried out on assignment from Stockholm Vatten AB as a part of a project developing new waste water treatment techniques. The goal of the theisis has been to evaluate an anaerobic membrane bioreactor for treatment of waste water from Hammarby Sjöstad. The bioreactor has not been heated and the main interest has been to study the gas production, power consumption and the reduction of organic matter and nutrients. The system has been completed with a reverse osmosis unit and a total of four batch runs have been made with good results. The use of reverse osmosis allows nutrient in the waste water to be reintroduced into circulation as the reverse osmosis concentrate can be used as crop nutrient. The membrane unit is of VSEP ("Vibratory Shear Enhanced Processing") type and an extensive membrane test has been conducted. This so called L-test helped determine the most suitable type of membrane for the system to allow a higher ±ux and thus lower power consumption. The L-test gave good results and a new membrane with a poresize diameter of 0,45 μm was used. The organic load on the bioreactor has been more or less constant, around 0,7 kg COD/day, during the seven weeks of testing. The reduction over the entire system including reverse osmosis has been large, around 99 % regarding organic matter and phosporus and 93 % for nitrogen, making the system suitable for waste water treatment except for high power consumption, around 2 kWh/m3. The production of methanegas has worked although it has been quite low, with average values of 0,13 m3 CH4/kg reduced COD. / Examensarbetet är utfört på uppdrag av Stockholm Vatten AB som en del av det pilotprojekt som utvärderar nya tekniker för avloppsvattenrening för Hammarby Sjöstad. Målsättningen med studien har varit att utvärdera ett system bestående av en anaerob membranbioreaktor för behandling av avloppsvatten från Hammarby Sjöstad. Bioreaktorn har inte varit uppvärmd och det som har studerats är reningseffekten, biogasproduktionen samt energiåtgången. Systemet har även innefattat en omvänd osmosanläggning och totalt har fyra försök med denna gjorts med goda resultat. Analyser har koncentrerats till att utvärdera reduktion av organiskt material över membranbioreaktorn och av närsalter och metaller över omvänd osmos anläggningen. Bakgrunden till att använda omvänd osmos är att öka återföringen av näringsämnen från avloppsvatten. Resultatet av försöken med omvänd osmos gav ett koncentrat med högt näringsinnehåll och låg halt av tungmetaller vilket ger möjligheten att sprida det på åkermark. Membranenheten är av typen VSEP ("Vibratory Shear Enhanced Processing") och ett membrantest har även utfötts för att finna det membran som passar systemet bäst med avseende på flöde och energiförbrukning. Det så kallade L-testet var omfattande och gav en klar bild över vad som skulle vara det bästa membranet. Det membran som visade sig passa systemet bäst var ett membran med en porstorlek på 0,45 μm. Belastningen av organiskt material på reaktorn under försöksperiodens sju veckor har varit mer eller mindre konstant och låg, cirka 0,7 kg COD/dygn. Reduktionen över hela systemet inklusive omvänd osmosanläggningen med avseende på organiskt material och fosfor har varit mycket hög, omkring 99 %. Reduktionen av kväve var som högst 93 %. Gasproduktionen har fungerat och har i genomsnitt varit omkring 0,13 m3 CH4/kg reducerad COD. Energiförbrukningen för systemet i motsvarande fullskala blev omkring 2 kwh/m3.

This study revealed that ammonium ion exchange of natural zeolite could be a feasible method of nitrogen removal and recovery from permeate from anaerobic membrane bioreactors (AnMBRs). NaCl concentrations optimized for chemical regeneration in batch experiments did not match those in continuous column tests. Instead, the mass ratio of Na+ to Zeolite-NH4+-N was significant for improving regeneration efficiency in column experiments; this mass ratio was 750 g Na+/g Zeolite-NH4+-N required for regeneration efficiency over 90% in 2 hours at pH 9. ???To decrease the NaCl dose in regeneration of exhausted zeolite, a high pH regeneration method was developed using an NaCl concentration of 10 g/L at pH 12 (the mass of Na+ to Zeolite-NH4+-N of 4.2 ) which achieved a regeneration efficiency about 85%. The recovery of ammonium nitrogen from the exhausted zeolite was assessed with air stripping followed by ammonia collection in an acid scrubber. The effects of shaking and air stripping were investigated in batch tests and the results showed the superiority of air stripping over shaking. Liquid circulation and air flow rates were varied for optimization of ammonia recovery in a continuous zeolite-packed column combined with a regeneration chamber and a stripping column. The liquid circulation rate had no significant effect on either the regeneration efficiency or the ammonia transfer efficiency from ammonium nitrogen to ammonia gas, while the ammonia transfer efficiency significantly increased with the air flow rate.??? Furthermore, the effect of pH on ammonia recovery was tested. Both the regeneration efficiency and the ammonia transfer efficiency were significantly improved with increasing pH. When the pH was increased from 9.5 to 12, the regeneration efficiency increased from 9.2% to 84% and the ammonia transfer efficiency increased from 54% to 92%. The nitrogen recovery process that combines zeolite ammonium exchange and air stripping can decrease chemical costs for regeneration of exhausted zeolite and efficiently collect ammonium nitrogen to be reused as fertilizers. Hence, the integrated nitrogen process can resolve the challenge of nitrogen removal in anaerobic membrane bioreactors treating organic wastewater in sustainable manners.

Aerobic (AeMBRs) and Anaerobic Membrane Bioreactors (AnMBRs) are an essential part of the advanced wastewater treatment options, which offer advantages in terms of higher effluent discharge and smaller footprints over the traditional wastewater treatment. This study evaluates the performance of (AnMBRs) by analyzing the cumulative effect of eleven physico-chemical parameters from the data obtained from the studies conducted from year 2000 onwards. Effect of various parameters such as Solid Retention Time (SRT), Hydraulic Retention Time (HRT), Mixed Liquor Suspended Solids (MLSS), influent Chemical Oxygen Demand (COD), Organic Loading Rate (OLR), influent COD, and temperature on the COD removal, methane production and membrane fouling were evaluated. Spearman’s correlation analysis was performed to investigate the impact of environmental and operational parameters on membrane fouling, COD reduction, EPS/SMP and methane production and explain the results. It should be noted that the literature used has all needed variables; incomplete data sets were removed for the regression analysis, in this case, the fouling rate may be estimated. Of these variables, the fouling rate was significantly correlated only with flux (r = 0.291, p =

Dans cette thèse ont été développés des modèles mathématiques pour les procédés de distillation membranaire à contact direct (DCMD) et avec balayage gazeux (SGMD) ainsi qu’un modèle sur l’hydrodynamique des bioréacteurs membranaires anaérobiques (AnMBRs) équipés d’un système de vibration membranaire induite (MMV). Les modèles pour la DCMD et la SGMD permettent de simuler le comportement des modules plats ou à fibres creuses sous différentes conditions opératoires, sans avoir recours aux données expérimentales ou à des équations empiriques pour les transferts de masse et de chaleur. Les modèles ont été validés avec des résultats expérimentaux et de la littérature et ont permis de déterminer l'influence de différents paramètres opérationnels et de la géométrie des modules sur les performances des procédés. Le modèle développé pour les AnMBRs équipés du système MMV permet d’étudier l’effet de la vibration membranaire sur l’hydrodynamique du réservoir. L’analyse paramétrique a permis d’étudier l’effet de la fréquence et de l’amplitude des vibrations sur la vitesse du fluide et la fraction volumique des solides dans le réservoir. Dans ce travail il a été démontré que les modèles proposés pourront être potentiellement appliqués à des études expérimentales préliminaires, l’optimisation des conditions opératoires, la conception des modules membranaires ainsi que pour l’estimation des coûts des procédés. / In this work have been developed general predictive models for direct contact membrane distillation (DCMD) and sweeping gas membrane distillation (SGMD) as well as a hydrodynamic model for anaerobic membrane bioreactors (AnMBRs) equipped with the induced membrane vibration (MMV) system. The DCMD and SGMD models allow simulating hollow fibre and flat sheet configurations under wide range of process conditions without empirical mass and heat transfer coefficients or laboratory experiments. The models have been validated with experimental and literature data. Indeed, the influence of operating conditions and membrane geometric characteristics on the process performance has been investigated. The model for AnMBRs with MMV studies the effect of the membrane vibration on the hydrodynamics of the AnMBR tank. The parametric study allows knowing, the effects of the vibration frequency and amplitude on the fluid velocity and volume fraction of solids. The conducted studies prove that all the proposed models would be potentially applied for the pre-experimental study, optimization of process conditions, design of membrane modules as well as for the further cost estimation of the processes.

Landfilling is the most widely used method for the disposal of municipal solid wastes (MSW) in the United States due to its simplicity and low cost. According to the 2014 report on Advancing Sustainable Materials Management by the USEPA, only 34% of the total MSW generated in the US was recycled, while 13% was combusted for energy recovery. In 2014, 53% of the MSW generated, (i.e. 136 million tons) in the US was landfilled. The treatment of landfill leachates, generated by percolation of water through the landfill, primarily due to precipitation, has been found to be one of the major challenges associated with landfill operation and management. Currently, leachates from most landfills are discharged into wastewater treatment plants, where they get treated along with domestic sewage. Issues associated with treatment of landfill leachates due to their high nitrogen and heavy metal content have been widely studied. Recently, it has been observed that the organic carbon in landfill leachates, specifically humic and fulvic acids (together referred to as "humic substances") contain aromatic groups that can absorb large amounts of ultraviolet (UV) light, greatly reducing the UV transmissivity in wastewater plants using UV disinfection as the final treatment step. This interference with UV disinfection is observed even when landfill leachates constitute a very small fraction (of the order of 1%) of the total volumetric flow into wastewater treatment plants. Humic substances are present as dissolved organic matter (DOM) and typically show very low biodegradability. Removing these substances using chemical treatment or membrane processes is an expensive proposition. However, the concentrations of humic substances are found to be reduced in leachates from landfill cells that have aged for several years, suggesting that these substances may be degraded under the conditions of long-term landfilling. The primary objective of this research was to use a two-stage process employing thermophilic pretreatment followed by a mesophilic anaerobic membrane bioreactor (AnMBR) to mimic the conditions of long-term landfilling. The AnMBR was designed to keep biomass inside the reactor and accelerate degradation of biologically recalcitrant organic carbon such as humic substances. The treatment goal was to reduce UV absorbance in raw landfill leachates, potentially providing landfills with an innovative on-site biological treatment option prior to discharging leachates into wastewater treatment plants. The system was operated over 14 months, during which time over 50% of UV-quenching organic carbon and 45% of UV absorbance was consistently removed. To the best of our knowledge, these removal values are higher than any reported using biological treatment in the literature. Comparative studies were also performed to evaluate the performance of this system in treating young leachates versus aged leachates. Next-generation DNA sequencing and quantitative PCR (qPCR) were used to characterize the microbial community in raw landfill leachates and the bioreactors treating landfill leachate. Analysis of microbial community structure and function revealed the presence of known degraders of humic substances in raw as well as treated landfill leachates. The total number of organisms in the bioreactors were found to be higher than in raw leachate. Gene markers corresponding to pathogenic bacteria and a variety of antibiotic resistance genes (ARGs) were detected in raw landfill leachates and the also in the reactors treating leachate, which makes it necessary to compare these ARG levels with wastewater treatment in order to determine if leachates can act as sources of ARG addition into wastewater treatment plants. In addition, the high UV absorbance of leachates could hinder the removal of ARBs and ARGs by UV disinfection, allowing their release into surface water bodies and aiding their proliferation in natural and engineered systems. / Ph. D. / Municipal solid waste is most often disposed by dumping it in landfills. Percolation of water through these landfills due to precipitation or the intrusion of surface or groundwater, results in the formation of landfill leachate, a mixture of organic and inorganic contaminants, at the bottom of the landfill. Landfills are therefore lined with special materials to prevent leachate from seeping into soil or groundwater and have sophisticated collection systems to periodically extract and dispose leachate. Perhaps the most commonly used method for the disposal of landfill leachates is discharge into wastewater treatment plants, where leachates can cause toxicity to biological processes due to their high organic load as well as their substantial heavy metal content. In the last decade or so, it has been established that leachates can absorb UV light considerably by virtue of aromatic organic compounds present in them, causing inhibition of UV disinfection in wastewater treatment. Thus, leachates must be appropriately treated to reduce their capacity to absorb UV light prior to discharge into wastewater treatment plants. This study employed a novel two – stage reactor system to treat landfill leachates in order to reduce their UV-quenching ability. The system was successfully operated over 14 months and was able to remove more than half of the UV light absorbing organic carbon from landfill leachate. Additionally, samples of biomass isolated from untreated landfill leachates and the reactors treating them revealed the potential presence of pathogenic bacteria and antibiotic resistance genes. Preliminary data suggests that landfill leachates might have large antibiotic resistance content, higher than that observed in wastewater and other engineered systems.