Bioelectrochemical Treatment of 1,4-Dioxane in the Presence of Chlorinated Solvents: Design, Process, and Sustainability Considerations

Abstract

1,4-Dioxane is one of the most frequently detected organic water contaminants and often co-occurs with chlorinated volatile organic compounds due to its use as solvent stabilizer. Its recalcitrance challenges natural attenuation processes and conventional water treatment technologies. Here, we examined the bioelectrochemical oxidation of 1,4-dioxane using dimensionally stable mesh electrodes in flow-through reactors coupled with bioaugmentation by Pseudonocardia dioxanivorans CB1190. 1,4-Dioxane influent concentrations were rapidly reduced from 100000 μg/L by more than 4 orders of magnitude to below our detection limit of 3 μg/L. The application of an electric potential was associated with a higher abundance of P. dioxanivorans CB1190 in both sessile and planktonic states. The presence of 5 mg/L 1,1-dichloroethene, the strongest known chlorinated solvent inhibitor of 1,4-dioxane biodegradation, reduced 1,4-dioxane degradation rates by factors of 2–4 inspite of >99% electrochemical removal. In comparison with direct electrochemical 1,4-dioxane oxidation, the coupling with biological oxidation reduced energy consumption, material usage, and, consequently, overall treatment costs by about 1 order of magnitude while generating lower amounts of disinfection byproducts. Our results establish that bioelectrochemical treatment is a synergistic, sustainable technology for water contaminated with 1,4-dioxane and chlorinated co-contaminants to meet strict regulatory thresholds.