Evaluation of iron coated natural sand for removal of dissolved arsenic from groundwater and develop sustainable filter media

Abstract

Drinking of untreated arsenic contaminated groundwater has suspected many inhabitants at the verge of chronic arsenicosis diseases. Develop a sustainable filter media has become an urgent need. In developing countries, practice of local sand material as filter media for removal of iron and arsenic is a common technique used daily. In this study, a relative capacities of the iron oxide-coated sand (IOCS) usually used in the conventional household filters was evaluated for removal of arsenic. The experimental study results have showed that the initial As (III) concentration of 500 μg L−1 was removed by IOCS at 10 g L−1 dose with an efficiency of 92% and natural sand removed at 68% of As (III) by a dose of 20 g L−1. Freundlich isotherm results for IOCS showed maximum adsorption at 7.2 μg g−1. The conversion of ferrous to ferric iron in natural groundwater system suggest that due to co-precipitation, ferric dosage of 10 mg L−1 at pH 7 for 2 hrs has showed that the optimum conditions for removing arsenic. Experimental results suggested that the iron flocs can remove up to 62% of As(III) from groundwater. The adsorption capacities of IOCS bed at a depths of 3 cm, 4 cm and 5 cm could remove initial arsenic concentrations of 100 μg L−1 at pH 7 as 66.87 μg g−1, 63.49 μg g−1, 57.08 μg g−1, respectively, by following the Thomas model. The results of iron coated sand suggest that IOCS material provide an economical and sustainable solution to remove the dissolved arsenic concentration from groundwater.