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

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

doi:10.3389/fmicb.2022.812991

Honghong Yuan, Zhongjian Li + Show 6 more

Open Access

https://doi.org/10.3389/fmicb.2022.812991

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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 (Icell, 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 Icell 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.

Highlights

Arsenic (As) contamination in groundwater possesses a serious threat to human and ecosystem health globally due to the high toxicity and ubiquity of As (Rodriguez-Freire et al, 2016; Wang et al, 2020)
To evaluate the overall As (V) removal efficiency, the bioelectrochemical system (BES) was operated in galvanostatic mode with an Icell of 30 mA
S(–II) was detected in the effluent (Supplementary Figure 1). If this BES technology is applied to the treatment of As-contaminated groundwater, the residual As can be removed through adsorption and membrane technology (Alka et al, 2021)

Summary

Introduction

Arsenic (As) contamination in groundwater possesses a serious threat to human and ecosystem health globally due to the high toxicity and ubiquity of As (Rodriguez-Freire et al, 2016; Wang et al, 2020). Groundwater constitutes the largest reservoir of drinking water. Drinking water has been identified as a major dietary source of inorganic As. Studies have shown that As pollution can lead to numerous diseases such as cancers, circulatory. The maximum permissible As concentration limit proposed by the World Health Organization (WHO, 2017) and the US Environmental Protection Agency (US-EPA, 2001) is 10 μg L-1 in the drinking water. More than 137 million people in over 70 countries have been exposed to a wide range of As in drinking water (Rahman et al, 2009; McArthur et al, 2016; Schwanck et al, 2016). There is an urgent need to develop methods that can efficiently remove As from groundwater to produce safe drinking water and prevent imminent health catastrophes

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