The use of perchlorate in solid propellants has led to subsurface contamination at numerous sites. Here, we investigate the application of bioelectrochemical treatment to stimulate naturally-occurring biological perchlorate reduction in contaminated groundwater under site-specific conditions at a location in the western United States. In this treatment process, both hydrogen from water electrolysis and organic carbon from CO<sub>2</sub> reduction are generated at the cathode, serving as electron donors for downgradient microbial perchlorate and co-contaminant reduction. We evaluated different electrode materials and proton-exchange membranes in a divided electrochemical reactor to optimize electron donor generation. Subsequently, we used original site soils in flow-through columns to compare perchlorate removal in electrochemically treated groundwater (both hydrogen and acetate as electron donors), indirectly treated groundwater (hydrogen as the only electron donor), and untreated groundwater (no added electron donor) to quantify microbial perchlorate reduction kinetics and elucidate the impacts of competing electron acceptors. To establish a mechanistic understanding of the microbial dynamics, we resolved microbial community structure and quantified gene expression associated with perchlorate reduction. Our findings demonstrate that bioelectrochemical treatment is a promising approach for the <i>in situ</i> remediation of perchlorate-contaminated groundwater and form a basis for pilot-scale evaluations.

Bioelectrochemical reduction of perchlorate in contaminated groundwater

2019 Spring National Meeting

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