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 IMPACTS OF FREE NITROUS ACID (FNA) ON STABLIZING FOOD WASTE (FW) AND SEWAGE SLUDGE (SS) FOR ANAEROBIC CO-DIGESTION(2021) Liu, Ruizhe; Li, Guangbin GL; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anaerobic digestion (AD) is a sustainable waste-to-energy method for converting organic wastes to methane. In this work, a pretreatment of food waste (FW) with free nitrous acid (FNA) was proposed, and various pretreatment times (4 hrs, 72 hrs, and 28 days) and FNA concentrations (1.07, 2.13, and 5 mg FNA-N/L) were tested to evaluate its effectiveness in stabilizing FW and sewage sludge (SS). Soluble chemical oxygen demand (sCOD), soluble protein (sP), and soluble polysaccharide (sPS) in the groups with 50%:50% (w/w VS) pretreated at 5 mg FNA-N/L for 72 hrs were significantly increased by 631, 530, and 780 %, respectively, compared with the control group without FNA addition. Additionally, less sulfide was detected in the groups with FNA addition, indicating an effective reduction in sulfide-odor during the storage/pretreatment of FW and SS. The potential of biogas production of FNA-pretreated FW was assessed using biochemical methane potential (BMP) test, and the results showed that the groups with FNA pretreatment produced up to 91.97% more methane than the group without FNA. The results from this work indicated an improved digestibility of FW and/or SS for AD using FNA pretreatment, and suggested the optimal pretreatment condition at 2 mg FNA-N/L for 24 hrs for FW and FW/SS.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 INCREASING EFFICIENCY AND SUSTAINABILITY OF WASTE-TO-ENERGY SYSTEMS USING BIOCHAR FOR HYDROGEN SULFIDE CONTROL AND LIFE CYCLE ASSESSMENT(2019) Choudhury, Abhinav; Lansing, Stephanie; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The research aim was to increase energy production efficiency and reduce the environmental impacts of waste-to-energy technologies, specifically anaerobic digestion (AD) of dairy manure (DM) and combustion of poultry litter (PL). The first objective was co-digestion of DM with gummy vitamin waste (GVW) to increase methane (CH4) yield. The GVW co-digestion treatments significantly increased CH4 yield by 126% - 151% compared to DM-only treatment and significantly decreased the H2S concentration in the biogas by 66% - 83% compared to DM-only. The second objective was understanding the effect of hydrogen sulfide (H2S) scrubber management, operation, and maintenance parameters on H2S removal efficiency. Even though the capital and operating costs for the two H2S scrubbing systems in this study were low (< $1500/year), they showed ineffective performance due to insufficient air injection, substitution of proprietary iron oxide-based H2S adsorbents for cheaper alternatives, and the lack of dedicated operators. The third objective was adsorption of H2S using Fe-impregnated biochar as a substitute for activated carbon (AC). Fe-impregnation of biochar led to a 4.3-fold increase in the H2S adsorption capacity compared to AC. When compared to unimpregnated biochars, Fe-impregnation led to an average 3.2-fold increase in the H2S adsorption capacity. The fourth objective was in-situ use of biochar in AD to remove H2S. In-situ biochar addition at the highest dose (1.82 g biochar/g manure total solids (TS)) resulted in an average H2S removal efficiency of 91.2%. Biochar particle size had no significant effect on H2S reduction. In-situ addition of Fe-impregnated biochar resulted in an average H2S removal efficiency of 98.5%. The fifth objective was a life cycle assessment (LCA) of a PL fluidized bed combustion (FBC) system. The LCA assessment showed that heating poultry houses using heat obtained from the combustion of PL in the FBC system had 32% lower climate change potential (CCP) compared to use of propane for heating poultry houses. However, analyzing the FBC system under a net positive electrical output scenario resulted in 66% less impact on CCP and a 48 – 98% reduction in environmental impacts compared to the previous scenario with net electricity input.Item FULL SCALE STUDY OF PATHOGEN, METAL POLLUTANTS, NUTRIENTS, AND POLYBROMINATED DIPHENYL ETHERS IN CLASS A BIOSOLIDS STABILIZED BY THERMAL HYDROLYSIS AND ANAEROBIC DIGESTION PROCESSES(2017) Wang, Xuanzhao; Torrents, Alba; Andrade, Natasha Almeida; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Class A biosolids are solid by-product of wastewater treatment which meet Environmental Protection Agency requirements to be used as fertilizer in farms, vegetable gardens, and can be sold directly to consumers. In 2014, this study’s target nutrient recovery facility adopted thermal hydrolysis pretreatment and anaerobic digestion to upgrade biosolids quality from Class B (previously lime-stabilized) to Class A. In order to certify if this newly produced material met all regulatory requirements, we performed laboratory analysis to characterize fecal coliforms, volatile solids, and metals content. In addition, we showed a baseline for nutrient management of total nitrogen, phosphorus, and the change in levels of polybrominated diphenyl ethers (PBDEs). Samples were collected for over a year since the start of THP-AD operation. Results were compared with the Class B biosolids produced at the same facility. Based on EPA standards, Class A biosolids were produced with stable quality after March, 2015, 16 weeks after process initiation. This work suggests that THP-AD is effective in producing Class A biosolids. In general, PBDEs in biosolids decreased from 1790 ± 528 (Class B) to 720 ± 110 µg/kg d.w. Our results suggest that the total levels of PBDEs decrease, however, the impact of the THP-AD on specific congeners are complex.Item From Grain to Waste: Repurposing Buffalo's Grain Elevators(2013) Behrens, Scott Derek; Rockcastle, Garth; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Buffalo River, as it winds its way through the city of Buffalo, New York, is home to some of the finest examples of grain elevators to be found anywhere in the United States. These remnants, which embody cultural values and traditions of a bygone industrial age, are currently threatened with abandonment and demolition. The city of Buffalo is actively promoting improvements to its industrial riverfront area and is interested in developing current building usage standards. This thesis will attempt to repurpose and reuse the historic grain elevator complexes that define the Buffalo River waterfront in order to better use the land and recreate a place within the historic industrial fabric of the city. The goal of this thesis will serve as an example of a method for design in derelict sites where grain elevators have lost their original purpose and identity, but have retained their architectural prominence.