Bioremediation of groundwater contaminated by a mixture of aromatic hydrocarbons and chlorinated solvents is typically challenged because these contaminants are degraded via distinctive oxidative and reductive pathway...Bioremediation of groundwater contaminated by a mixture of aromatic hydrocarbons and chlorinated solvents is typically challenged because these contaminants are degraded via distinctive oxidative and reductive pathways,thus requiring different amendments and redox conditions.Here,we provided the proof-of-concept of a single-stage treatment of synthetic groundwater containing toluene and trichloroethene(TCE)in a tubular bioelectrochemical reactor,known as a“bioelectric well”.Toluene was degraded by a microbial bioanode(up to 150 mmol L^(-1) d^(-1))with a polarized graphite anode(t0.2 V vs.SHE)serving as the terminal electron acceptor.The electric current deriving from microbially-driven toluene oxidation resulted in(abiotic)hydrogen production(at a stainless-steel cathode),which sustained the reductive dechlorination of TCE to less-chlorinated intermediates(i.e.,cis-DCE,VC,and ETH),at a maximum rate of 500 meq L^(-1) d^(-1),in the bulk of the reactor.A phylogenetic and functional genebased analysis of the“bioelectric well”confirmed the establishment of a microbiome harboring the metabolic potential for anaerobic toluene oxidation and TCE reductive dechlorination.However,Toluene degradation and current generation were found to be rate-limited by external mass transport phenomena,thus indicating the existing potential for further process optimization.展开更多
The toxic and recalcitrant polychlorinated biphenyls （PCBs） adversely affect human and biota by bioaccumulation and biomagnification through food chain. In this study, an anaerobic microcosm was developed to extensi...The toxic and recalcitrant polychlorinated biphenyls （PCBs） adversely affect human and biota by bioaccumulation and biomagnification through food chain. In this study, an anaerobic microcosm was developed to extensively dechlorinate hexa- and hepta-CBs in Aroclor 1260. After 4 months of incubation in defined mineral salts medium amended PCBs （70μmol· L^-1） and lactate （10 mmol· L^-1）, the culture dechlorinated hexa-CBs from 40.2% to 8.7% and hepta-CBs 33.6% to 11.6%, with dechlorination efficiencies of 78.3% and 65.5%, respectively （all in moL ratio）. This dechlorination process led to tetra-CBs （46.4%） as the predominant dechlorination products, followed by penta- （22.1%） and tri-CBs （5.4%）. The number of meta chlorines per biphenyl decreased from 2.50 to 1.41. Results of quantitative real-time PCR show that Dehalococcoides cells increased from 2.39 × 10^5±0.5× 10^5 to 4.99 ×10^7±0.32 ×10^7 copies mL^-1 after 120 days of incubation, suggesting that Dehalococcoides play a major role in reductive dechlorination of PCBs. This study could prove the feasibility of anaerobic reductive culture enrichment for the dehalogenation of highly chlorinated PCBs, which is priorto be applied for in situ biorernediation of notorious halogenated compounds.展开更多
基金This study was supported by the European Union’s Horizon 2020 project ELECTRA(www.electra.site)under grant agreement No.826244.
文摘Bioremediation of groundwater contaminated by a mixture of aromatic hydrocarbons and chlorinated solvents is typically challenged because these contaminants are degraded via distinctive oxidative and reductive pathways,thus requiring different amendments and redox conditions.Here,we provided the proof-of-concept of a single-stage treatment of synthetic groundwater containing toluene and trichloroethene(TCE)in a tubular bioelectrochemical reactor,known as a“bioelectric well”.Toluene was degraded by a microbial bioanode(up to 150 mmol L^(-1) d^(-1))with a polarized graphite anode(t0.2 V vs.SHE)serving as the terminal electron acceptor.The electric current deriving from microbially-driven toluene oxidation resulted in(abiotic)hydrogen production(at a stainless-steel cathode),which sustained the reductive dechlorination of TCE to less-chlorinated intermediates(i.e.,cis-DCE,VC,and ETH),at a maximum rate of 500 meq L^(-1) d^(-1),in the bulk of the reactor.A phylogenetic and functional genebased analysis of the“bioelectric well”confirmed the establishment of a microbiome harboring the metabolic potential for anaerobic toluene oxidation and TCE reductive dechlorination.However,Toluene degradation and current generation were found to be rate-limited by external mass transport phenomena,thus indicating the existing potential for further process optimization.
基金Acknowledgements This work was financial supported by grants from the National Natural Science Foundation of China （Grant Nos. 51108014 and 41671310）.
文摘The toxic and recalcitrant polychlorinated biphenyls （PCBs） adversely affect human and biota by bioaccumulation and biomagnification through food chain. In this study, an anaerobic microcosm was developed to extensively dechlorinate hexa- and hepta-CBs in Aroclor 1260. After 4 months of incubation in defined mineral salts medium amended PCBs （70μmol· L^-1） and lactate （10 mmol· L^-1）, the culture dechlorinated hexa-CBs from 40.2% to 8.7% and hepta-CBs 33.6% to 11.6%, with dechlorination efficiencies of 78.3% and 65.5%, respectively （all in moL ratio）. This dechlorination process led to tetra-CBs （46.4%） as the predominant dechlorination products, followed by penta- （22.1%） and tri-CBs （5.4%）. The number of meta chlorines per biphenyl decreased from 2.50 to 1.41. Results of quantitative real-time PCR show that Dehalococcoides cells increased from 2.39 × 10^5±0.5× 10^5 to 4.99 ×10^7±0.32 ×10^7 copies mL^-1 after 120 days of incubation, suggesting that Dehalococcoides play a major role in reductive dechlorination of PCBs. This study could prove the feasibility of anaerobic reductive culture enrichment for the dehalogenation of highly chlorinated PCBs, which is priorto be applied for in situ biorernediation of notorious halogenated compounds.
