Assessment of the Occurrence, Toxicity, and Biotransformation of Disinfection Byproducts of 1,4-Dioxane

As a potential human carcinogen, 1,4-dioxane is threating our drinking and surface water quality in NJ and a number of other populated states in the US. Unfortunately, current water and wastewater treatments are marginally effective to remove 1,4-dioxane. Inadvertently, as the end treatment prior to the discharge, disinfection processes (e.g., chlorination and advance oxidation) may promote the reaction between 1,4-dioxane and disinfecting oxidants to form halogenated dioxane derivatives (HDDs). Previous toxicity tests have proved potent adverse effects of HDDs. In addition to their enhanced bioaccumulation tendency and elongated persistency, HDDs may emerge as widespread water contaminants influencing the human health and natural biota. In this proposed work, we will advance our fundamental knowledge of chemical reaction mechanisms and kinetics for HDDs formation at different conditions, such as the pH, exposure time, contact time and temperature. The distribution and abundance of 1,4-dioxane and HDDs will be further investigated at effluent of WWTPs, swimming pools, and drinking water systems in northern NJ. Dynamics and yield of HDDs will be evaluated and compared when different disinfection approaches are employed. For further toxicity evaluation of HDDs, the lethal dosage and mutagenic potential test based on model bacteria such as E. coli and Salmonella will be studied and assessed using the regression model. We will also study the biotransformation of HDDs using bacterial isolates that metabolize or cometabolize 1,4-dioxane. This will be the very first research that comprehensively uncovers the occurrence, toxicity, and attenuation of HDDs in engineered systems.