Bioelectrochemical system accelerates reductive dechlorination through extracellular electron transfer networks

Su-Hao Chen; Zheng-Tao Li; He-Ping Zhao

doi:10.1016/j.envres.2023.116645

Bioelectrochemical system accelerates reductive dechlorination through extracellular electron transfer networks

Environ Res. 2023 Oct 15:235:116645. doi: 10.1016/j.envres.2023.116645. Epub 2023 Jul 11.

Authors

Su-Hao Chen¹, Zheng-Tao Li¹, He-Ping Zhao²

Affiliations

¹ MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China.
² MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China. Electronic address: zhaohp@zju.edu.cn.

PMID: 37442263
DOI: 10.1016/j.envres.2023.116645

Abstract

Bioelectrochemical system is considered as a promising approach for enhanced bio-dechlorination. However, the mechanism of extracellular electron transfer in the dechlorinating consortium is still a controversial issue. In this study, bioelectrochemical systems were established with cathode potential settings at -0.30 V (vs. SHE) for trichloroethylene reduction. The average dechlorination rate (102.0 μM Cl·d^-1) of biocathode was 1.36 times higher than that of open circuit (74.7 μM Cl·d^-1). Electrochemical characterization via cyclic voltammetry illustrated that electrostimulation promoted electrochemical activity for redox reactions. Moreover, bacterial community structure analyses indicated electrical stimulation facilitated the enrichment of electroactive and dechlorinating populations on cathode. Metagenomic and quantitative polymerase chain reaction (qPCR) analyses revealed that direct electron transfer (via electrically conductive pili, multi-heme c-type cytochromes) between Axonexus and Desulfovibrio/cathode and indirect electron transfer (via riboflavin) for Dehalococcoides enhanced dechlorination process in BES. Overall, this study verifies the effectiveness of electrostimulated bio-dechlorination and provides novel insights into the mechanisms of dechlorination process enhancement in bioelectrochemical systems through electron transfer networks.

Keywords: Biocathode; Bioelectrochemical systems; Electron transfer networks; Trichloroethene dechlorination.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biodegradation, Environmental
Electricity
Electrodes
Electrons*
Oxidation-Reduction
Trichloroethylene* / chemistry

Substances

Trichloroethylene