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

Abstract

g r a p h i c a l a b s t r a c t Keywords:Bioelectrochemical dechlorination 1,2-Dichloroethane Reductive dechlorination Microbial biocathode a b s t r a c tThe 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 À300 mV to À900 mV vs. the standard hydrogen electrode). This process was primarily dependent on electrolytic H 2 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 À300 mV, where no H 2 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.

Bioelectrochemical Dechlorination of 1,2‐DCA with an AQDS‐Functionalized Cathode Serving as Electron Donor

“…The capability of the AQDS‐functionalized electrode to stimulate the reductive dechlorination of 1,2‐DCA by a mixed dechlorinating culture was assessed by means of batch experiments. The experiments were carried out in the 2‐chamber bioelectrochemical cell described previously . Initially, the working electrode's compartment of the bioelectrochemical cell was filled with 110 mL of anaerobic mineral medium and a 40 mL inoculum consisting of a 1,2‐DCA dechlorinating enrichment culture .…”

“…Recently, a new approach has been pursuit to tackle some of these disadvantages, which is based on the use of a potentiostatically controlled graphite electrode to selectively and efficiently deliver the needed electrons to the reductively dechlorinating microbial communities , . So far, the efficacy of this bioelectrochemical approach has been verified, at least at the laboratory scale, on several different chlorinated aliphatic hydrocarbons (CAHs), namely perchloroethene (PCE) , trichloroethene (TCE) , and even 1,2‐DCA , . In this respect, a previous study from our group has shown that 1,2‐DCA can be reductively dechlorinated to harmless ethene, via dihaloelimination, using a polarized graphite cathode (from –300 mV to –900 mV vs .…”

“…In this respect, a previous study from our group has shown that 1,2‐DCA can be reductively dechlorinated to harmless ethene, via dihaloelimination, using a polarized graphite cathode (from –300 mV to –900 mV vs . standard hydrogen electrode, SHE) serving as the sole electron donor . Notably, high values (up to 70%) of coulombic efficiency (i.e., the yield of current utilization for the reductive dechlorination process) were obtained when the cathode was maintained at –300 mV vs .…”

1,4‐Dioxane‐contaminated groundwater remediation in the anode chamber of a microbial fuel cell

“…Groundwater is often contaminated by a variety of organic and inorganic contaminants, for example, 1,4‐dioxane is often found co‐contaminated with chlorinated hydrocarbons (e.g., TCE and TCA; Stefan & Bolton, ; Zhang, Gedalanga, & Mahendra, ). Degradation of chlorinated hydrocarbons has been widely studied on cathodes of bioelectrochemical systems; however, the process generally needs supplying external voltage (Aulenta et al, ; Leitão et al, ; Pous, Balaguer, Colprim, & Puig, ). By generating electrical power during 1,4‐dioxane anodic degradation, power input for remediating 1,4‐dioxane and chlorinated hydrocarbon co‐contaminated groundwater would be reduced.…”

Electro-assisted groundwater bioremediation: Fundamentals, challenges and future perspectives

“…This system can be managed to achieve a complete mineralization of PCE in real groundwater in a continuous-flow mode, where highly-localized treatment zones are established (Aulenta et al, 2011;Lohner et al, 2011). A further improvement in energy efficiency can be achieved by establishing a direct delivery of electrons between the electrodes and degrading bacteria (Leitão et al, 2015) or channeled by other co-existed dechlorinating species (Patil et al, 2014).…”