title: A cost-effective system for in-situ geological arsenic adsorption from groundwater.
abstract: An effective and low-cost in-situ geological filtration system was developed to treat arsenic-contaminated groundwater in remote rural areas. Hangjinhouqi in western Hetao Plain of Inner Mongolia, China, where groundwater contains a high arsenic concentration, was selected as the study area. Fe-mineral and limestone widely distributed in the study area were used as filter materials. Batch and column experiments as well as field tests were performed to determine optimal filtration parameters and to evaluate the effectiveness of the technology for arsenic removal under different hydrogeochemical conditions. A mixture containing natural Fe-mineral (hematite and goethite) and limestone at a mass ratio of 2:1 was found to be the most effective for arsenic removal. The results indicated that Fe-mineral in the mixture played a major role for arsenic removal. Meanwhile, limestone buffered groundwater pH to be conducive for the optimal arsenic removal. As(III) adsorption and oxidation by iron mineral, and the formation of Ca-As(V) precipitation with Ca contributed from limestone dissolution were likely mechanisms leading to the As removal. Field demonstrations revealed that a geological filter bed filled with the proposed mineral mixture reduced groundwater arsenic concentration from 400 μg/L to below 10 μg/L. The filtration system was continuously operated for a total volume of 365,000L, which is sufficient for drinking water supplying a rural household of 5 persons for 5 years at a rate of 40 L per person per day.
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China; School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
authors.forename: Huimei
authors.initials: H
authors.lastname: Shan
authors.forename: Teng
authors.initials: T
authors.lastname: Ma
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
authors.forename: Hongyin
authors.initials: H
authors.lastname: Han
authors.forename: Yamin
authors.initials: Y
authors.lastname: Deng
authors.forename: Xin
authors.initials: X
authors.lastname: He
authors.forename: Yihui
authors.initials: Y
authors.lastname: Dong
mesh_terms: D000327:Adsorption; D001151:Arsenic / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry; D003362:Cost-Benefit Analysis; D052918:Environmental Restoration and Remediation / Q000191:economics / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry; D005374:Filtration / Q000379:methods; D060587:Groundwater / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry; D008903:Minerals / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000191:economics / Q000379:methods*
chemical_list: D005290:Ferric Compounds; D058085:Iron Compounds; D008903:Minerals; D014874:Water Pollutants, Chemical; C094886:goethite; C000499:ferric oxide; D002119:Calcium Carbonate; D001151:Arsenic
keywords: Arsenic removal; Fe-mineral; Geological filter; In-situ; Limestone