Honors Theses

Date of Award

5-2025

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biomedical Sciences

Faculty Mentor

Kaushik Venkiteshwaran

Advisor(s)

Terrence J. Ravine, Richard A. O’Brien, Padmamalini Thulasiraman

Abstract

Quaternary ammonium compounds (QACs) are highly effective as disinfectants, herbicides, and pesticides; thus, overuse causes elevated levels of residual toxicity in domestic and industrial wastewater. QACs can be toxic to essential bacteria breaking down pollutants in wastewater treatment plants (WWTPs) and can remain untreated in effluent, harming the environment, and contributing to antibiotic resistance, posing risks to human health. Novel boronium-based antimicrobial compounds have demonstrated efficacy in eliminating bacteria, fungi, and viruses. If the boronium compounds exhibit lower residual toxicity, they could offer a promising alternative to QACs. Because these compounds are still in development, their potential toxicity to the biological WWTP process is yet to be fully evaluated. Therefore, the objective of this study is to conduct a comparative toxicity analysis between the QAC (alkyl (ethylbenzyl) dimethylammonium chloride) and three novel boronium compounds. The analyses performed follow guidelines set by the Organization for Economic Cooperation and Development (OECD) and utilize a standard freeze-dried aerobic bacterial culture that closely mimics WWTPs’ mixed bacteria communities. Toxicity is assessed by measuring and comparing the dissolved oxygen consumption rate (DOCR) of the bacterial culture, which was fed an ideal substrate, in the presence of the test compounds at varying concentrations. Experiments were conducted by comparing QAC to boronium compounds at concentrations ranging from 0.1 to 22 mg/L, based on expected residual levels in wastewater. Initial results show that the QAC is less toxic than the boronium C16 compound and that the QAC is less toxic than the pyridine boronium C16 compound. However, the bacteria used in this study exhibited signs of adaptation to the boronium C16 compound with concentrations of 22 mg/L, 5.5 mg/L and 0.344 mg/L and to the pyridine boronium C16 compound with concentrations of 11 mg/L, 5.5 mg/L, 2.75 mg/L and 1.375 mg/L. Additionally, initial results show that the Gemini salt is less toxic than the QAC. The duration of future experiments for the QAC and the three boronium compounds will extend beyond 7 days to better capture bacterial adaptation and to determine if boronium compounds exhibit lower residual toxicity than QACs.

Download

Share

COinS