The Role of Ozonation as an Advanced Oxidation Process for Attenuation of 1,4-Dioxane in Potable Reuse Applications

The combination of ozone and hydrogen peroxide (O-3/H2O2), or the peroxone process, has often been used as an advanced oxidation process (AOP) in groundwater remediation and drinking water applications. This historical precedent sometimes leads to the misconception that H2O2 addition is required to achieve AOP conditions during ozonation. This is not the case for secondary or tertiary wastewater effluent applications, in which ozone reacts with abundant dissolved organic carbon (DOC) to generate hydroxyl radicals ((OH)-O-center dot). This study demonstrates the use of ozone with and without H2O2 addition to yield (OH)-O-center dot exposures (up to 10(-9) M-s) capable of achieving > 0.5-log(10) attenuation of the industrial contaminant and probable human carcinogen 1,4-dioxane. This low molecular weight compound is commonly used as a surrogate when establishing AOP design criteria for potable reuse applications. DOC-normalized ozone doses (i.e., O-3/DOC ratios) of similar to 1.0 and similar to 1.3 achieved 0.5-log(10) attenuation of 1,4-dioxane with O-3/H2O2 and O-3, respectively. Also, a predictive model based on (OH)-O-center dot exposure was accurate within approximately +/- 10%. These results suggest that ozonation's role as an AOP, even in the absence of H2O2, should be acknowledged in regulatory frameworks to reduce unnecessary treatment redundancy and facilitate broader implementation of potable reuse.