CEE Seminar: Chloramine Photochemistry for Potable Water Reuse

Abstract: Ultraviolet-driven advanced oxidation processes (UV/AOP) are becoming increasingly important for potable water reuse to remove trace chemical contaminants from wastewater effluent. This seminar will discuss the unique aqueous photochemistry of the overlooked but important chloramines for water reuse applications. Membrane treatment processes including microfiltration (MF) and reverse osmosis (RO) are employed prior to any UV/AOP in water reuse facilities. Chloramines are deliberately generated in the feed water to minimize membrane biological fouling. Because of their small molecular size and neutral charge, chloramines easily diffuse through RO membranes and subsequently will undergo photolysis in the UV/AOP. We investigated the efficiencies of chloramines in degrading 1,4-dioxane under low-pressure UV lamp photolysis. The photolysis of chloramines produced amine and halide radicals, which further transformed to a series of reactive radical species that assist the contaminant degradation. The presence of dissolved oxygen further decreased the reactivity. This study shows that the presence of chloramines in UV/AOP as carry-over chemical residuals from membrane treatment processes can also be harnessed as an oxidant beneficial to water reuse. We are also currently conducting pilot-scale photochemical experiments utilizing chloramine photolysis with our industrial partners. Considering the perspective of potable water reuse, an efficient utilization of chloramine photochemistry can lead to a more sustainable water management.

Bio: Haizhou Liu is an assistant professor in the Department of Chemical and Environmental Engineering at University of California, Riverside. He received his Ph.D. at University of Washington, and completed postdoctoral training at UC Berkeley before joining UC Riverside in 2013. Liu's research interests include water chemistry, water reuse and purification, environmental remediation, electrochemistry and catalysis. His current and recent research has been sponsored by the National Science Foundation, Department of Interior, Department of Agriculture and Water Research Foundation. Liu is a member of several professional societies and currently serves on the International Water Association's specialist committee on metals and toxic substances in drinking water. He received an Emerging Investigator Award in water engineering and technology from the Royal Society of Chemistry in 2016, and a National Science Foundation Faculty Early Career Development (CAREER) Award in 2017.