Date of Award

Spring 2024

Project Type

Thesis

Program or Major

Civil and Environmental Engineering

Degree Name

Master of Science

First Advisor

Paula J Mouser

Second Advisor

James P Malley Jr.

Third Advisor

Jenna Luek

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a broad class of chemicals known for their environmental persistence and unique thermal and chemical stability which has led them to be used in a variety of products including paper, carpets, clothes, cosmetics, food packaging, kitchen ware, chrome plating, and aqueous film forming foams (AFFFs). Their resistance to biochemical degradation has led regulators to be interested in reducing PFAS loads to the environment and sources that humans are exposed to (e.g. drinking water). Recent studies have shown that concentrations of some terminal PFAS increase after secondary (biological) wastewater treatment indicating that precursor compounds are biotransforming to terminal PFAS. There is a lack of information known on specific precursor transformation pathways and rates in a wastewater treatment facility (WWTF). This thesis explores the use of a novel dialysis membrane system to study PFAS precursor biotransformations in situ. The membrane system was spiked with n-ethyl perfluorooctane sulfonamide ethanol (N-EtFOSE), a known precursor to perfluorooctanesulfonic acid (PFOS), and studied under both laboratory and field conditions. Differences in degradation based on dissolved oxygen concentrations (aerobic vs. anoxic) and temperature (summer vs. winter) were determined. A proposed degradation pathway was developed, and degradation rates and half-lives were calculated. The results of this research can inform regulators on the fate of a PFAS precursor in a wastewater system and the membrane system can be utilized in future studies researching PFAS precursor transformation in engineered systems or in the natural environment (e.g. surface waters).

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