Directional bioelectrochemical dechlorination of trichloroethene to valuable ethylene by introduction poly-3-hydroxybutyrate as a slow release carbon source

[Display omitted] •SOC coupled BES showed 2.2 times higher k of dechlorination kinetics.•High TCE dechlorination rate with 94% recovery of ethylene by introducing PHB,•Electroactive dechlorinators involved in accelerated TCE dechlorination to 1,2-DCE.•Dehalococcoides in suspension participated in 1,2-DCE dechlorination to ethylene.•Simultaneous dechlorination and ethylene recovery with low carbon risk and biorisk. Bioelectrochemical dechlorination is one of the prospective and economic strategies for remediation of halogenated organics contaminated site, however, exploring the way of system construction with high detoxification efficiency and low organocarbon risk is still challenging. Herein, the slow-release organic carbon-sources (SOCs) coupled bioelectrochemical dechlorination system with generally accelerated trichloroethene (TCE) dechlorination performance and controllable organocarbon release was reported. It is interestingly found the introduction of Poly-3-hydroxybutyrate (PHB) achieved the greatly improved dechlorination efficiency (2.23 times improved k value) with valuable ethylene as a major metabolite (recovery ratio of 94.00 ± 1.62 %), reflecting the superior TCE detoxification and ethylene recovery potential. Microbial molecular mechanism analysis revealed the enriched electroactive dechlorinators (Geobacter and Desulfovibrio) in cathode representing the positive correlation (r > 0.8, p