Development of a Simple, Effective Ceramic Filter for Arsenic Removal

Abstract

A simple, low-cost filtration system composed of a ceramic filter, an iron net and iron bacterial sludge was developed to remove arsenic (As) from groundwater. The ceramic filter, made of an 80% clay soil and 20% rice bran mixture on a weight basis, was combined with the iron net and the iron bacterial sludge in a reactor, and the assembly (As removal filter) was tested for its ability to remove As from synthetic groundwater. Synthetic groundwater with a varying composition of As(III), ferrous iron (Fe(II)) and phosphate phosphorus (P) was filtered on a daily basis. The results showed that both Fe(II) in groundwater and those released from the iron net were oxidized biologically and/or physico-chemically and that As and P were effectively removed by adsorption and/or co-precipitation processes. The concentrations of Fe(II) and P in groundwater were decisive factors in the removal of As. Groundwater Fe concentrations of ≥ 2 mg/L and P concentrations of ≤ 3 mg/L with an Fe/P molar ratio of ≥ 3.0 were required to achieve an effluent As concentration of less than 50 µg/L from raw water containing 500 µg/L of As(III). This simple, inexpensive filter could be used to treat As in contaminated regions.