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

This study uses a membrane-less reactor to explore the bioelec-trochemical remediation of real contaminated groundwater fromchlorinated aliphatic hydrocarbons (CAHs) and nitrates. Theresearch focuses on testing a column-type bioelectrochemicalreactor to stimulate in situ degradation of contaminants throughthe supply of electrons by a graphite granules biocathode. After apreliminary laboratory characterization and operation with a syn-thetic feeding solution, a field test is conducted in a real contami-nated site, where the reactor demonstrates effective degradationof CAHs and inorganic anions. Notably, the cathodic potentialpromotes the reductive dechlorination of chlorinated species.Simultaneously, nitrate reduction, sulfate reduction, and metha-nogenesis occurr, influencing the overall coulombic efficiency ofthe process. The use of real groundwater, compared to the syn-thetic medium, significantly decreases the coulombic efficiencyof reductive dechlorination, dropping from 2.43% to 0.01%.Concentration profiles along the bioelectrochemical reactor allowfor a deeper description of the reductive dechlorination rate atdifferent flow rates, as well as increase the knowledge aboutreduction and oxidation mechanisms. Scaling up the technologypresents several challenges, including the optimization of cou-lombic efficiency and the management of competing microbialmetabolisms. The study provides a valuable contribution towardadvancing bioelectrochemical technologies for the bioremedia-tion of complex contaminated sites.