title: Electrochemically induced oxidative removal of As(III) from groundwater in a dual-anode sand column.
abstract: In situ treatment of high-arsenic groundwater cost-effectively is still challenging. We proposed an in situ treatment approach which utilizes O2 produced from groundwater electrolysis to increase the redox potential for oxidative removal of arsenic. A sand column was configured to simulate groundwater flow in an aquifer, and a stable anode, a stable cathode and an iron anode were arrayed in an upward mode in the column to evaluate the performance on arsenic removal from the groundwater induced by the oxidative precipitation of Fe(2+) by O2. As(III) at 500μg/L was efficiently oxidized to As(V) by the stable anode followed by the reactive oxidants produced from Fe(II)-O2, and total As were completely removed by the newly formed amorphous iron hydroxides. Quantitative models for the dependence of As(III) oxidation, total As removal and Fe(II) oxidative precipitation on the flow rate and the current density applied to Fe anode were developed. The presence of humic substance promoted the oxidation of As(III) on the stable anode but inhibited the oxidation and removal induced by Fe(II) oxidative precipitation. A stable performance on As(III) oxidation and removal was observed in a 10-day continuous operation. Results from this study prove that groundwater electrolysis could be applicable for oxidative removal of As(III) in porous media, with a controllable and lasting treatment efficiency.
authors.affiliation: State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China; School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China.
authors.forename: Man
authors.initials: M
authors.lastname: Tong
authors.affiliation: State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China. Electronic address: yuansonghu622@cug.edu.cn.
authors.forename: Songhu
authors.initials: S
authors.lastname: Yuan
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, CA 94404, United States.
authors.forename: Zimeng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China.
authors.forename: Mingsen
authors.initials: M
authors.lastname: Luo
authors.affiliation: State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China; School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China.
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Wang
keywords: Arsenic; Electrolysis; Ferrous iron; Groundwater remediation; Oxidation