Removal of Arsenate From Groundwater by Cathode of Bioelectrochemical System Through Microbial Electrosorption, Reduction, and Sulfuration

Honghong Yuan; Yumeng Huang; Ouyuan Jiang; Yue Huang; Dongsheng Qiu; Williamson Gustave; Xianjin Tang; Zhongjian Li

doi:10.3389/fmicb.2022.812991

Removal of Arsenate From Groundwater by Cathode of Bioelectrochemical System Through Microbial Electrosorption, Reduction, and Sulfuration

Front Microbiol. 2022 Mar 11:13:812991. doi: 10.3389/fmicb.2022.812991. eCollection 2022.

Authors

Honghong Yuan^{1

2}, Yumeng Huang³, Ouyuan Jiang¹, Yue Huang¹, Dongsheng Qiu¹, Williamson Gustave⁴, Xianjin Tang¹, Zhongjian Li^{3

5}

Affiliations

¹ Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, College of Environmental and Resource Sciences, Institute of Soil and Water Resources and Environmental Science, Zhejiang University, Hangzhou, China.
² ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, China.
³ Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Zhejiang University, Hangzhou, China.
⁴ School of Chemistry, Environmental and Life Sciences, University of The Bahamas, Nassau, Bahamas.
⁵ Institute of Zhejiang University - Quzhou, Quzhou, China.

Abstract

Arsenate [As(V)] is a toxic metalloid and has been observed at high concentrations in groundwater globally. In this study, a bioelectrochemical system (BES) was used to efficiently remove As(V) from groundwater, and the mechanisms involved were systematically investigated. Our results showed that As(V) can be efficiently removed in the BES cathode chamber. When a constant cell current of 30 mA (I _cell , volume current density = 66.7 A/m³) was applied, 90 ± 3% of total As was removed at neutral pH (7.20-7.50). However, when I _cell was absent, the total As in the effluent, mainly As(V), had increased approximately 2-3 times of the As(V) in influent. In the abiotic control reactor, under the same condition, no significant total As or As(V) removal was observed. These results suggest that As(V) removal was mainly ascribed to microbial electrosorption of As(V) in sludge. Moreover, part of As(V) was bioelectrochemically reduced to As(III), and sulfate was also reduced to sulfides [S(-II)] in sludge. The XANES results revealed that the produced As(III) reacted with S(-II) to form As₂S₃, and the residual As(III) was microbially electroadsorbed in sludge. This BES-based technology requires no organic or chemical additive and has a high As(V) removal efficiency, making it an environment-friendly technique for the remediation of As-contaminated groundwater.

Keywords: arsenate removal; bioelectrochemical system; microbial electrosorption; microbial reduction; sulfuration.