Design parameters for a laterite arsenic filter.

Abstract

As arsenic contamination in groundwater is currently a serious problem in developing countries, a reliable, cost-effective and easy-to-use method for arsenic removal is highly demanded. This project tackled the problem by studying useful data for designing an arsenic filter using laterite. This was achieved by performing column studies on the effects of laterite size and contact time. The project focused on arsenic (V) removal in neutral pH range with an arsenic concentration of 250 ppb. The effects of ionic strength or interference ions were not studied. This report presents findings from the project on (1) the feasibility of using large-sized laterite to remove arsenic in column-type continuous-flow operation mode, (2) the suitable size of laterite for best removal result, (3) the minimum empty bed contact time (EBCT) to achieve 96% removal, (4) the operational EBCT and (5) the water quality of the effluent. These results showed that large-sized laterite was capable of removing arsenic in the column operation. The appropriate size should be from 2 to 4 mm. The minimum EBCT was 0.34 hours while the operational one was 3.4 hours. There was no problem with water quality of the effluent in terms of pH and turbidity. In addition, calculation for a filter bed design was performed and the service time turned out to be 45 days. Last but not least, it is recommended that the removal efficiency of As(III) of the filter and a pilot scale for actual groundwater should be studied.