Chloramine Photochemistry for Potable Water Reuse
Haizhou Liu
Chemical and Environmental Engineering, University of California - Riverside
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.
