Field Test of a Bioelectrochemical Membrane‐Less Reactor for Chlorinated Aliphatic Hydrocarbon and Nitrate Removal from a Contaminated Groundwater

This study evaluates a membrane-less bioelectrochemical reactor in a real groundwater remediation scenario, targeting chlorinated aliphatic hydrocarbons and nitrate contamination. Electron supply via graphite granules biocathode stimulates reductive dechlorination and nitrate reduction, despite competing processes like sulfate reduction and methanogenesis. Field results reveal effective contaminant degradation, highlighting critical considerations for scaling up bioelectrochemical remediation technologies at complex environmental sites.

This study uses a membrane-less reactor to explore the bioelectrochemical remediation of real contaminated groundwater from chlorinated aliphatic hydrocarbons (CAHs) and nitrates. The research focuses on testing a column-type bioelectrochemical reactor to stimulate in situ degradation of contaminants through the supply of electrons by a graphite granules biocathode. After a preliminary laboratory characterization and operation with a synthetic feeding solution, a field test is conducted in a real contaminated site, where the reactor demonstrates effective degradation of CAHs and inorganic anions. Notably, the cathodic potential promotes the reductive dechlorination of chlorinated species. Simultaneously, nitrate reduction, sulfate reduction, and methanogenesis occurr, influencing the overall coulombic efficiency of the process. The use of real groundwater, compared to the synthetic medium, significantly decreases the coulombic efficiency of reductive dechlorination, dropping from 2.43% to 0.01%. Concentration profiles along the bioelectrochemical reactor allow for a deeper description of the reductive dechlorination rate at different flow rates, as well as increase the knowledge about reduction and oxidation mechanisms. Scaling up the technology presents several challenges, including the optimization of coulombic efficiency and the management of competing microbial metabolisms. The study provides a valuable contribution toward advancing bioelectrochemical technologies for the bioremediation of complex contaminated sites.

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