title: In-situ arsenic remediation by aquifer iron coating: Field trial in the Datong basin, China.
abstract: An aquifer Fe-coating technology was evaluated for in-situ As remediation. The groundwater in the aimed aquifer has low dissolved Fe(II) concentration and high As(III) concentration, which has a low affinity toward Fe-oxides/hydroxides. To overcome these challenges, dissolved Fe(II) (5.0 mM) and NaClO (2.6 mM) were injected into the studied aquifer to promote the formation of Fe oxides/hydroxides and to oxidize As(III) into As(V), thus removing aqueous As via adsorption and/or co-precipitation. During field experiment, As concentration in groundwater from the pumping well significantly decreased. Fe and As speciation calculations indicate that incorporation of negatively charged As(V) into goethite was the probable mechanism for As removal. Both chemical sequential extraction results and spectroscopic data also support that alternating injection of Fe(II) and NaClO can achieve aquifer Fe coating and immobilize As via adsorption onto Fe oxides/hydroxides. Geochemical modelling further confirms that although competition for sorption sites between As and other dissolved species is expected in the natural groundwater system, high surface area of the Fe oxides/hydroxides can provide sufficient sites for As retention. The ability to effectively decrease As concentration of in-situ aquifer Fe-coating technology indicates that this approach should have extensive applicability to similar high As groundwater occurred worldwide.
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China. Electronic address: xjxie@cug.edu.cn.
authors.forename: Xianjun
authors.initials: X
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Kunfu
authors.initials: K
authors.lastname: Pi
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Yaqing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China; Pacific Northwest National Laboratory, Richland, WA 99354, USA.
authors.forename: Chongxuan
authors.initials: C
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Junxia
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Yapeng
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Chunli
authors.initials: C
authors.lastname: Su
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Teng
authors.initials: T
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China. Electronic address: yx.wang@cug.edu.cn.
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Wang
keywords: Arsenic; Complexation; Geochemical modelling; In-situ remediation; Iron coating