Honors Theses and Capstones

Date of Award

Spring 2024

Project Type

Senior Honors Thesis

College or School

CEPS

Department

Civil and Environmental Engineering

Program or Major

Environmental Engineering

Degree Name

Bachelor of Science

First Advisor

Paula Mouser

Second Advisor

James Malley Jr.

Third Advisor

Jennifer Harfmann

Abstract

Per- and polyfluoroalkyl substances, or PFAS, are a group of manmade organic chemicals that have been widely used since the 1940’s due to their resistance to heat, water, and oil. These compounds are associated with negative health outcomes including poor thyroid function, reproductive toxicity, and carcinogenicity. Because products with PFAS are widely used in residential settings, and because many PFAS do not completely degrade during wastewater treatment/handling, septic systems may be an important non-point source of PFAS to groundwater. Many homes that have septic systems, which discharge wastewater effluent to the subsurface, also use groundwater as a drinking water source; therefore, understanding what types of PFAS are found in septic systems as well as how they transform is important for protecting rural drinking water supplies. The goals of this project were to: (1) map the transformation pathways of six PFAS known as fluorotelomer carboxylic acids (FTCAs) using chemical transformation prediction software; (2) delineate how FTCAs may degrade in septic system environments; and (3) more broadly identify biotransformation trends for FTCAs relevant to other natural and engineered systems. Research on how PFAS transform in septic systems remains limited, therefore the findings of this research will support a growing body of knowledge that serves to help predict the types of compounds that are being discharged from these systems to the subsurface. The results of this study suggest that some FTCAs follow a distinct breakdown pathway despite the number of carbon fluorine bonds they have, and the environmental conditions of individual septic systems control the extent to which transformation pathways occur.

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