Sequential Reductive and Oxidative Biodegradation of Chloroethenes Stimulated in a Coupled Bioelectro-Process

Abstract

This article for the first time demonstrates successful application of electrochemical processes to stimulate sequential reductive/oxidative microbial degradation of perchloroethene (PCE) in mineral medium and in contaminated groundwater. In a flow-through column system, hydrogen generation at the cathode supported reductive dechlorination of PCE to cis-dichloroethene (cDCE), vinyl chloride (VC), and ethene (ETH). Electrolytically generated oxygen at the anode allowed subsequent oxidative degradation of the lower chlorinated metabolites. Aerobic cometabolic degradation of cDCE proved to be the bottleneck for complete metabolite elimination. Total removal of chloroethenes was demonstrated for a PCE load of approximately 1.5 μmol/d. In mineral medium, long-term operation with stainless steel electrodes was demonstrated for more than 300 days. In contaminated groundwater, corrosion of the stainless steel anode occurred, whereas DSA (dimensionally stable anodes) proved to be stable. Precipitation of calcareous deposits was observed at the cathode, resulting in a higher voltage demand and reduced dechlorination activity. With DSA and groundwater from a contaminated site, complete degradation of chloroethenes in groundwater was obtained for two months thus demonstrating the feasibility of the sequential bioelectro-approach for field application.

Dechlorination and organohalide-respiring bacteria dynamics in sediment samples of the Yangtze Three Gorges Reservoir

“…Lower chlorinated compounds like DCE and VC also can be degraded by aerobic degradation Schmidt et al 2010;Zhao et al 2010;Zhao et al 2011). At contaminated field sites, anaerobic dechlorination could stop at cis-DCE or VC, followed by aerobic mineralization of the lower chlorinated metabolites Lohner et al 2011;Tiehm and Schmidt 2011). A similar sequential anaerobic/aerobic degradation might be possible also in the Yangtze TGR, taking into consideration the periodical water level fluctuations and expected spatiotemporal dynamics of the hydrochemical parameters (Bergmann et al 2012;Kranzioch and Tiehm 2012).…”

Enhanced decolorization of azo dye in a small pilot-scale anaerobic baffled reactor coupled with biocatalyzed electrolysis system (ABR–BES): A design suitable for scaling-up

“…In comparison, BESs can be applied to reduce oxidized forms of contaminants on the cathode to less toxic or more stable products. For example, a number of reduction reactions have been achieved using BESs for reducing nitrobenzene (Wang et al, 2011, antibiotics chloramphenicol (Liang et al, 2013), copper (II) (Tao et al, 2011), halogenated compounds (Lohner et al, 2011;Strycharz et al, 2010) and azo dyes (Mu et al, 2009;Cui et al, 2012Cui et al, , 2014. Recently, our research group developed a membrane-less, up-flow biocatalyzed electrolysis reactor (UBER) that successfully reduced azo dye up to 97.5 ± 1.0% (Cui et al, , 2014.…”

Accelerated decolorization of azo dye Congo red in a combined bioanode–biocathode bioelectrochemical system with modified electrodes deployment

“…Thus, it is necessary to investigate the decolorization performance of azo dyes using biocathode BES. Furthermore, there are some studies on combination of anode and cathode in BES for wastewater or groundwater treatment (Li et al, 2010;Lohner et al, 2011;Sun et al, 2011a;Wen et al, 2010). Considering the bioanode decolorization at present, aircathode single chamber MFC has been used extensively (Cao et al, 2010;Hou et al, 2011bHou et al, , 2012Xu et al, 2013).…”