A comprehensive study of treatment of arsenic in water combining oxidation, coagulation, and filtration.

http://dx.doi.org/10.1016/j.jes.2015 1001-0742/© 2015 The Research C Arsenic is one of the most common inorganic contaminants in groundwater worldwide, mainly due to the release of naturally occurring arsenic from aquifer sediments (Amini et al., 2008; Li and Cai, 2015; Rahman et al., 2015). Naturally occurring arsenic exists predominantly in arsenate and arsenite species in groundwater. Arsenite is more toxic and more difficult to remove from water than arsenate (Hughes et al., 2011; Pena et al., 2005; Bang et al., 2005; Du et al., 2015). Development of effective technologies for removal of arsenic from water by coagulation and adsorption requires in-depth knowledge of arsenic chemistry, surface interactions of arsenic species and coexisting solutes with the adsorbents, and redox transformation of arsenic species. Recently, Cui et al. (2015) conducted a comprehensive study on the treatment of arsenic by ferric salts. The research spanned from field evaluation of a household coagulation filtration system to spectroscopic analysis of chemical bonding structures of adsorbed arsenic species with surface functional groups. Moreover, the leachability of arsenic in the solid residue generated during the water treatment was tested for determination of the proper disposal options of the waste material. Several technologies have been used for removal of arsenic fromwater, including coagulation or coprecipitation with ferric salts, adsorption with metal oxides and hydroxides, treatment with zero valent iron, filtrationwith anion exchange resins, and membrane filtration (Banerjee et al., 2008; Jing et al., 2009; Bordoloi et al., 2013; Xia et al., 2014). Coagulation processes are typically used in large drinking water treatment plants and industrial wastewater treatment systems. Granular metal hydroxides and oxides, such as iron, titanium, aluminum, and zirconium, can be easily used in small water treatment systems and water filters for households, although the cost of granular adsorbents is higher than that of ferric salts. Coagulation with ferric salts, such as ferric sulfate and chloride, is one of the most cost-effective processes for arsenic treatment, because the chemicals are readily available