Persistent organic contaminants such as 1,4-dioxane or per- and polyfluoroalkyl substances (PFASs) have been widely detected in water resources across the U.S. Co-contaminant interactions with frequently comingled chlorinated solvents or aqueous film forming foam (AFFF) ingredients further challenge natural degradation processes and remediation technologies. Here, we examine the benefits of coupling electrochemical oxidation of 1,4-dioxane with aerobic biodegradation by Pseudonocardia dioxanivorans CB1190 in flow-through column reactors. The novel doped tin oxide mesh electrodes revealed superior performance compared to previously applied Ti/IrO2-Ta2O5 mesh electrodes, with electrode surface area-normalized 1,4-dioxane degradation rates higher by a factor of 20 at an order of magnitude less electric energy consumption. After inoculating the reactors with CB1190, 1,4-dioxane removal rates further increased from 181 to 837 mg/hm2, reducing 1,4-dioxane influent concentrations from 105,000 μg/L by several orders of magnitude to below our detection limit of 3 μg/L. 1,1-Dichloroethene (1,1-DCE), a strong inhibitor of 1,4-dioxane metabolic biodegradation, was removed from the aqueous phase by up to &gt;99 %, yet still caused some inhibition in bioelectrochemical experiments. Furthermore, we explored the coupling of electrolysis with biodegradation by both Trametes versicolor cultures and pure laccase enzymes for the destruction of PFASs. While mineralization of highly persistent perfluoroalkyl sulfonates was achieved, rates were substantially slower in AFFFs than in the absence of organic co-contaminants. In conclusion, our results demonstrate that bioelectrochemical oxidation is a promising synergistic approach for the treatment of groundwater contaminated with persistent organic pollutants in mixed contaminant plumes.

Bioelectrochemical oxidation of recalcitrant 1,4-Dioxane and Per- and Polyfluoroalkyl substances in mixed contaminant plumes

2019 Spring National Meeting

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