Theses and Dissertations from UMD
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Item HEATED RESISTANCE: THERMAL TREATMENT TECHNOLOGY MITIGATION OF BIOLOGICAL WASTES’ ANTIBIOTIC RESISTANCE AND GENE MOBILITY IN WASTE SYSTEMS.(2023) Poindexter , Carlton; Lansing, Stephanie; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The burgeoning global threat of antimicrobial resistance (AMR) has policy makers,veterinarians, farmers, and physicians re-evaluating antibiotic stewardship. Worldwide, millions of people are affected by multidrug resistant bacteria. Human and animal waste are primary transporters of antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistant genes (ARGs) through rural and urban systems. Resistance within biological waste, as it moves through the landscape and sanitary/manure infrastructure to adjacent natural systems, is yet to be fully understood. The various environmental conditions, bacterial composition, and genetic factors result in highly complex interdependent relationships that influence the occurrence and dissemination of ARB and ARGs. Understanding the fate of ARB and movement of ARGs is critical to evaluating environmental and anthropogenic impact. Agricultural systems and wastewater treatment plants are target locations for quantifying connections between clinical and animal antibiotic use and environmental AMR. Waste management techniques/technologies, such as compositing and anerobic digestion (AD), have been shown to be effective in combating AMR. Studies have highlighted temperature as a key environmental determinant that could influence antibiotic degradation, ARG, and ARB abundance. The proposed research examines advanced heat-based manure and wastewater technological capacity for AMR reduction, while measuring treatment impact on ARG dissemination. Focusing on the reduction of AMR within biological waste treatment and the distribution of AMR factors into the environment. A key metric to understanding AMR is accurate detection and quantitation of antibiotic concentration within manure and other biosolid waste products. The first phase of this dissertation research focused on the development of a liquid chromatography in tandem with mass spectrometry (LC-MS/MS) method for detecting multi-class antibiotics residuals in various manure substrates. To combat the challenges of manure heterogeneity, this work focused on novel extraction methodology to achieve higher recovery of tetracyclines, macrolides, sulfonamides, and beta lactams simultaneously in a complex manure matrix. The method includes a two-step, liquid-solid extraction using 10 mL of 0.1 M EDTA-McIlviane buffer followed by 10 mL of methanol. Reporting total antibiotic recoveries of 67–131% for tetracyclines, 56% for sulfonamide, 49–53% for macrolides, and 1.3–66% for β-lactams. This method is novel in its application to four different manure substrate and utilization for waste risk assessment. This developed method was used for antibiotic quantification throughout the three thermal treatment studies to determine antibiotic concentrations, degradation, and monitor agricultural contributions to environmental AMR. The following research extensively focused on the evaluation of three advanced, high temperature waste treatment technologies on the mitigation of antibiotic resistance factors, including a composting rotary drum bedding recovery unit (BRU), thermophilic (55°C) and mesophilic (35°C) AD, and thermal hydrolysis pretreatment to reduce antibiotics, ARGs, and ARB. The assessment of environmental components, such as metals, bacterial community, and nutrient composition, are also included to determine any relational trends. The BRU study was conducted as a mass balance analysis to highlight antibiotics, ARGs and ARB partitioning within the BRU system. Dairy manure samples were collected over 24-hour period as the manure was treated with a solid-liquid separator producing two streams of substrates (liquids and separated solid), with the separated solid fraction continuing to the high temperature BRU processing. This study generated a mass flow analysis of manure and partitioning of antibiotic resistance factors throughout the manure treatment system. The study indicated that most of the manure mass containing the AMR factors goes untreated following solid-liquid separation, with 95% of the mass pumped to a storage lagoon and 5% proceeding to BRU processing. The removal of antibiotic residuals during BRU processes was insignificant, yet the BRS processing was 100% effective in removing the ARB examined. Five (Intl1, sul1, tetQ, tetX and tetM) of the eight ARGs were found to have significant reduction (>95%) following the thermophilic rotary drum composting portion of the BRU system. While the three other ARGs (tetW, ermB and bla2) remained constant despite treatment. An AD experiment was implemented as lab-scale destructive assay, highlighting antibiotic removal at two temperature and over time. This destructive batch assay used 18 sets of triplicate AD reactors filled with antibiotic spiked dairy manure and incubated under anerobic conditions at 35°C or 55°C for 43 days. Triplicates bottles destructively sampled at six time points (Day 0, 3, 9, 21, 36, and 43) to generate a degradation curve. The antibiotic erythromycin was more efficiently degraded under mesophilic conditions, with 100% removal by Day 36 compared to 97% reduction for thermophilic conditions during the 43-day digestion period. Though the higher temperature conditions proved better for oxytetracycline degradation, with 66% removal compared to only 22% removal for mesophilic conditions. ARG removal was dependent on the bacterial community, as the different conditions selected for various bacteria. While both conditions proved to be effective in reducing most of the ARGs (4-5 out of 8 genes tested), enrichment of other resistance genes was also documented. The tetW gene was found to increase >81% for both digester temperatures, highlighting the variety of bacteria harboring resistance genes and their varied responses to environmental conditions. The ermB genes was found to be located on the intl1 mobile genetic element and likely resided within bacteria that was not heat tolerant. This study highlighted the role of residential digester bacteria in harboring and potentially transferring resistance genes. The thermal hydrolysis (THP) technology ability to extensively lysis substrates was examined with subsequent AD for its impact on reducing antibiotic resistance factors. Comparative analysis of THP processing on spiked diary manure and wastewater biosolids followed by mesophilic digestion at 35°C was conducted to document substrate response to the treatment. AD was conducted as a destructive assay for 30 days with a 4-point sample curve (Day 0, 10, 20 and 30). This study can be found in the appendix. In addition to the lab and field work described above, this body of research also included a review and a proposed communication model for antibiotic resistance education for the general public. Lay audiences’ exposure and understanding of complex natural issues, such as AMR and climate change, are essential to behavioral changes and potentially legislative actions. By surveying and evaluating various aspects of scientific communication, this research empathized five rhetorical elements of storytelling shown to influence audience reception to scientific messaging. Communication techniques, such as narrative structure, normalization of the subject using human scaling, non-agentive language, trusted experts for message delivery, and future simulation, were all analyzed and reviewed for their effectiveness and incorporated into a mock model for presenting information about AMR. Bridging gaps between research institutions and the public is key to generating more inclusive spaces for innovation and mitigating issues interwoven within the built and natural environment.Item EFFECTS OF FULL-SCALE THERMAL HYDROLYSIS-ANAEROBIC DIGESTION ON THE TEMPORAL TRENDS OF POLYBROMINATED DIPHENYL ETHERS IN BIOSOLIDS AND THEIR PHYSICAL AND BIOLOGICAL DEGRADATION DURING WASTEWATER TREATMENT(2020) Motley, Taylor Ann; Torrents, Alba; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Biosolids produced at wastewater treatment plants (WWTPs) are rich in recovered nutrients and are often recycled through soil amendment on agricultural land. Advanced solids treatment strategies, including thermal hydrolysis pretreatment (THP) and anaerobic digestion (AnD), are utilized to produce cleaner, safer biosolids based on EPA classifications. Despite the phase-out of the flame retardant polybrominated diphenyl ethers (PBDEs) from commercial use in the U.S., they are still present in biosolids and can be degraded to toxic byproducts during solids treatment. Their transformation during solids treatment is not well understood. This work shows that while phase-outs of PBDEs did not affect their concentrations in biosolids from the target WWTP, the implementation of THP-AnD treatment in 2014 led to increased PBDE degradation during solids treatment. This significantly lowered PBDE concentrations and shifted congener distribution to favor smaller, more toxic congeners in final biosolids compared to lime-stabilized biosolids historically produced at the target WWTP. Comparisons between the target WWTP and other AnD facilities without THP revealed that more efficient PBDE degradation occurred during THP-AnD treatment despite lower abundances of debrominating bacteria in digesters. Future work will examine if PBDE degradation during THP-AnD treatment is due to physical or biological processes.Item PREVENTION AND TREATMENT OF POLYCHLORINATED BIPHENYLS IN SEDIMENTS - SOURCES AND SOLUTIONS(2019) Jing, Ran; Kjellerup, Birthe Veno; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)PCBs are classified as one of the persistent organic pollutants (POPs) with high toxicity and have undesirable effects on the environment and on humans. Once released into the environment PCBs could bioaccumulate within the food chain, due to their high affinity for organic materials. Recently, studies indicated PCBs can potentially enter a wastewater treatment plant (WWTP) system and be discharged via wastewater effluents thereby further contaminating the downstream environments. This study evaluated the potential for bioremediation of polychlorinated biphenyls (PCBs) in the effluent from a large WWTP. It was found that the continuous effluent was responsible for the majority of the discharged PCB into the receiving river (1821 g for five years), while the intermittent discharge contributed 260 g over the five years. The average number of chlorine per biphenyl for the detected PCB congeners showed a 19% difference between the two types of effluent, which indicated a potential for organohalide respiration of PCBs during the continuous treatment. This was further supported by a high level of tri-, tetra- and penta- chlorinated congeners accounting for 75% of the anaerobically respired PCBs. Potential for aerobic degradation and thus biomineralization of PCBs were identified for both effluents. In addition, the similarity of organohalide respiring (OHR) microbial populations in biosolids and intestinal human biofilms was determined by applying a bioinformatics approach. The OHR populations of the communities were analyzed from existing American and Chinese human intestinal microbiomes. The results of the biosolids analysis showed increased amounts of products from PCB respiration. Simultaneously, experiments with organohalide respiration of PCE in biosolids samples showed significant decreases in PCE concentration after 46 days (28-92%). Subsequently, it was evaluated if the OHR microbial populations in biosolids were similar to those present in intestinal human biofilms by applying a bioinformatic approach. The OHR populations of the communities were analyzed from existing American and Chinese human intestinal microbiomes. The overall groups Proteobacteria, Bacteroides, Actinobacteria, and Firmicutes phyla dominated the microbiomes in all datasets. The OHR groups in biosolids and intestinal biofilms included Dehalogenimonas, Dehalobacter, Desulfitibacter, Desulfovibrio, Sulfurospirillum, Clostridium, and Comamonas. The results of this study showed that several OHR phyla were present in all samples independent of origin. Wastewater and intestinal microbiomes also contained OHR phyla. Finally, biofilms made up by the OHR bacteria Dehalobium chlorocoercia DF-1 were inoculated on the surface of the pinewood biochar particles. The mole percent of the total PCE in the headspace decreased from 100% to 70.4%±17.6% for the rest of nine mesocosms which suggested that the D. chlorocoercia DF-1 biofilm converted PCE to TCE. The gene copy numbers of DF-1 biofilm from nine mesocosms which are ranging from 1.95×108 to 8.30×108 gene copies/g pinewood biochar. The biochar-biofilms were subsequently applied to PCB contaminated sediment from the Grass River in Michigan, USA. The goal was to evaluate the organohalide respiration of the PCB contaminated sediments in the absence/presence of the biofilm and free-floating inoculum.Item Integration of Sustainable Infrastructure at a Neighborhood Scale(2006-12-20) Binder, Michael P; Kelly, Brian; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)By concentrating power generation, water treatment and waste management facilities at large centralized sites on the edge of its cities, modern industrial society allows us to ignore our responsibility for the damage we are doing to the environment. This thesis project proposes the integration and distribution of neighborhood-scaled power and waste management functions throughout our urban centers, demonstrating the efficacy of localized infrastructure based on sustainable natural and man-made cycles, making it simultaneously beautiful and providing a desirable amenity to the residents. The heart of this thesis project is the design for an indoor garden space which also integrates solar power management, nature-inspired wastewater treatment and solid waste recycling. The program will include an environmental education center using the facility as an operational example. A site in Northwest Washington DC, bounded by New Jersey Ave., New York Ave., North Capitol and K Streets has been selected for its redevelopment opportunities.