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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Advancing Monitoring and Mitigation of Antibiotic Resistance in Wastewater Treatment Plants and Water Reuse Systems

Majeed, Haniyyah JaRae 22 October 2020 (has links)
Wastewater treatment plants (WWTPs) receive a confluence of sewage containing antibiotics, antibiotic resistant bacteria, antibiotic resistance genes (ARGs), and pathogens, thus serving as key point of interest for the surveillance of antibiotic resistance (AR) dissemination. This thesis advances knowledge about the fate of AR indicators throughout treatment and reuse. The field study informs approaches for monitoring AR at a WWTP by characterizing the resistome (i.e., full profile of ARGs) and microbiome across eight sampling events via metagenomic sequencing, complemented by antibiotic data. The WWTP significantly reduced the total load of ARGs and antibiotics, although correlations between ARGs and antibiotics were generally weak. Quantitative polymerase chain reaction was applied to validate the quantitative capacity of metagenomics, whereby we found strong correlations. The influent and effluent to the WWTP were remarkably stable with time, providing further insight into the sampling frequency necessary for adequate surveillance. The laboratory study examined the effects of commonly applied disinfection processes (chlorination, chloramination, and ultraviolet irradiation [UV]) on the inactivation of antibiotic resistant pathogens and corresponding susceptible pathogens in recycled and potable water. Further, we evaluated their regrowth following disinfection by simulating distribution. Acinetobacter baumannii, an environmental opportunistic pathogen, regrew especially well following UV disinfection, although not when a disinfectant residual was present. Enterococcus faecium, a fecal pathogen, did not regrow following any disinfection process. There were no significant differences between water types. The findings of this study emphasize a need to move beyond the framework of assessing treatment efficacy based on the attenuation of fecal pathogens. / Master of Science / Wastewater treatment plants (WWTPs) have traditionally been designed and further enhanced to minimize environmental contamination caused by solid waste, fecal pathogens, nutrients (e.g., nitrogen), and organic matter. However, treatment has not been optimized to remove the contaminants of emerging concern (CECs) investigated in this thesis: antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotics. WWTPs are key point of interest for local and global surveillance of antibiotic resistance as they can receive the aforementioned CECs (via human excretion or improper disposal) from various sources (e.g., residences, hospitals). Antibiotic resistant bacteria have caused 2.8 million infections and subsequently 35,000 deaths in the United States each year. Considering treated wastewater can serve as a route of exposure for humans, potential spread of antibiotic resistance by WWTPs is of high priority to mitigate from a public health perspective. In the first study utilizing a technology to assess the full complement of ARGs in a given sample, we observed that the total load of ARGs was removed by approximately 50% across wastewater treatment, on average; total antibiotic load exhibited a similar reduction. The second study demonstrated that antibiotic resistant environmental opportunistic pathogen (i.e., pathogens which take advantage of the "opportunity" to infect an immunocompromised host, especially thriving in low nutrient engineered systems), Acinetobacter baumannii, possesses the ability to regrow following disinfection in the absence of a disinfectant residual. In contrast, antibiotic resistant Enterococcus faecium, an opportunistic pathogen of fecal origin, was successfully inactivated and unable to regrow. The findings of this study emphasize a need to move beyond the framework of assessing treatment efficacy based on the attenuation of fecal pathogens.
12

Biodegradation of toxic wastes by immobilized microorganisms

Livingston, Andrew Guy January 1989 (has links)
No description available.
13

Modelling of the extractive membrane bioreactor process

Pavasant, Prasert January 1997 (has links)
No description available.
14

Crossflow microfiltration of sewage effluents

Till, Steven W. January 1999 (has links)
No description available.
15

The role of environmental effects and Acinetobacter spp. in enhanced biological phosphate removal

Jones, M. January 1996 (has links)
No description available.
16

Landfill as an anaerobic filter for the co-disposal of phenolic wastewaters

Watson-Craik, I. A. January 1987 (has links)
No description available.
17

Urban stormwater treatment by artificial wetlands

Cutbill, Linda Beverley January 1997 (has links)
No description available.
18

The effect of media size on biological aerated filter performance

Kent, Tanya Denise January 1998 (has links)
No description available.
19

The development of a predictive model for the removal of helminth eggs during rapid sand filtration

Dunn, Andrew John January 1991 (has links)
No description available.
20

Nitrogen removal from horizontal rotor oxidation ditch systems

Wood, A. January 1983 (has links)
No description available.

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