UV photolysis of monochloramine and free chlorine are increasingly considered in advanced oxidation processes (AOPs) for potable water reuse. 1,4-dioxane (1,4-D) is  a common trace organic and ubiquitous contaminant in drinking water. Due to its small size and neutral charge, 1,4-D can bypass membrane treatment systems and is treated using UV/AOPs. This study investigated the distribution of 1,4-D transformation byproducts during monochloramine and free chlorine photolysis. 1,4-D oxidation byproducts were identified using GC-MS and HPLC-UV, and their toxicological responses were determined via standard cyto- and geno-toxicity assays. Water matrix effects were examined at various 1,4-D dosages and solution pHs. Results showed that glycolaldehyde, formaldehyde, and 1,4-dioxan-2-one, which are more toxic than 1,4-D, are the major oxidation byproducts. The distribution of oxidation byproducts varied with changing oxidant-to-1,4-D ratio and solution pH. Furthermore, toxicological responses of the mixture during UV/AOP was driven by aldehydes and ketone byproducts. Results demonstrated that with higher UV fluence, the byproducts can be further degraded into less toxic products. The findings from this study allow for future optimization of UV/AOP treatment to reduce toxic byproduct formation in water reuse treatment trains.<br/>

Investigation of 1,4-dioxane oxidation byproducts during UV advanced oxidation processes

2019 Fall National Meeting

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