Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Civil Engineering

Degree Level

Undergraduate

Department

Civil Engineering

Advisor/Mentor

Zhang, Wen

Committee Member

Fernstrom, Eric

Second Committee Member

Braham, Andrew

Abstract

The increasing need for clean water has paved the way for the creation of systems for reusing water, such as wastewater treatment plants (“WWTPs”), to provide potable water. But in recent years, such systems have raised concerns about the distribution of antibiotic resistance genes (“ARGs”). Bacteria are adapting to antibiotics by the evolution of resistance mechanisms, such as high mutation rates and horizontal transfer. The presence of ARGs, particularly tetracycline ("tetA") resistance genes, in wastewater effluents is of concern, as they can survive treatment, spread to bodies of water, and pose a threat to human health. In this study, the impact of treatment processes on the fate of tetA in WWTPs has been analyzed. Five stages were sampled, including grit removal, activated sludge, clarification, granular filtration, and UV treatment. They were then quantified for tetA gene copies by qPCR. The results indicated that clarification had a significant reduction in tetA gene copies, while granular filtration had no reduction. Interestingly, UV exposure increased the number of tetA gene copies, potentially resulting from mutations in DNA or DNA extraction issues. These findings reveal that the current WWTP processes used cannot effectively remove ARGs, suggesting that improvements in treatment processes are necessary. Although wastewater reuse is promising, the presence of ARGs in treated wastewater represents a public health threat as well as a global threat to antibiotic resistance. The treatment strategies should be optimized and targeted to mitigate ARGs to guarantee that the reuse of water does not contribute to the spread of resistant bacteria.

Keywords

Antibiotic resistance genes; antbiotics; wastwater; wastwater treatment plants

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