Date of Award
Doctor of Philosophy (PhD)
Karl G. Linden
Urs von Gunten
Advanced water treatment technologies are being evaluated and implemented for treating organic micropollutants in water. Included among several viable technologies is a collection of advanced oxidation processes. Of primary interest in water are UV- and ozone-based oxidation systems. UV-hydrogen peroxide and ozone-hydrogen peroxide are advanced oxidation technologies appropriate for treating water contaminated with trace levels of organic chemicals. Unlike water treatment processes such as activated carbon and air stripping which transfer chemicals from one physical phase to another, these technologies are capable of destroying chemicals, and transforming them to degradation products. Although this destruction of contaminants is generally beneficial, the formation of byproducts (from the water matrix) or transformation products (from the micropollutants) that retain harmful biological activity is a possibility.
The objectives of this thesis were designed in order to assess the possible formation of toxic byproducts following oxidative treatment. A parallel analytical and toxicological potential analysis utilizing both analytical and biological tools following the oxidative degradation of several chemical contaminants found on the United States Environmental Protection Agency's Candidate Contaminant List 3 was performed, including following the changes in genotoxicity (mutagenicity), estrogenicity, and neurotoxicity while the contaminants were undergoing oxidative treatment. Mutagenicity dominated with regard to formation of toxicity post-oxidation in the contaminants tested. However, most chemical contaminants were amenable to advanced oxidation treatment, and no formation of toxicity was observed.
The synergistic use of biological filtration following advanced oxidation was explored, as providing an additional barrier to treatment could prove useful for the removal of various transformation products. Both biological sand and biologically activated carbon were studied with respect to the removal of genotoxic chemical byproducts. Assimilable organic carbon removal is an additional driver for implementing biological filtration downstream of an oxidation processes. The formation of assimilable organic carbon with regards to UV-based oxidation processes was explored. The UV-based process was found to cause no increase in assimilable organic carbon concentration when undergoing both low and medium pressure UV photolysis.
A policy review was conducted that included an exploration into group contaminant regulation, using the USEPA Contaminant Candidate List 3 as a framework
Group contaminant regulations by both structure (biological mode of action) and the contaminants intended use or purpose was performed. A lack of correlation existed between the health and occurrence data generated within each grouping parameter. An alternative approach to aid in emerging contaminant regulation was provided that included an effect-directed analysis that could act as an early warning system for water utilities with respect to unintended constituents or chemical byproducts.
Parker, Austa Marie, "Assessing Advanced Oxidation Transformation Products" (2015). Civil Engineering Graduate Theses & Dissertations. 495.