Bioelectrochemically-assisted reductive dechlorination of 1,2-dichloroethane by a Dehalococcoides-enriched microbial culture

•1,2-Dichloroethane is dechlorinated to ethene with an electrode as electron donor.•1,2-Dichloroethane dechlorination rate and yield depend on the set cathode potential.•Dehalococcoides is responsible for H2-mediated bioelectrochemical dechlorination.

The aim of this study was to verify the possibility to use a polarized graphite electrode as an electron donor for the reductive dechlorination of 1,2-dichloroethane, an ubiquitous groundwater contaminant. The rate of 1,2-DCA dechlorination almost linearly increased by decreasing the set cathode potential over a broad range of set cathode potentials (i.e., from −300 mV to −900 mV vs. the standard hydrogen electrode). This process was primarily dependent on electrolytic H2 generation. On the other hand, reductive dechlorination proceeded (although quite slowly) with a very high Coulombic efficiency (near 70%) at a set cathode potential of −300 mV, where no H2 production occurred. Under this condition, reductive dechlorination was likely driven by direct electron uptake from the surface of the polarized electrode. Taken as a whole, this study further extends the range of chlorinated contaminants which can be treated with bioelectrochemical systems.

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