Arsenic and iron removal from water using constructed soil filter—a novel approach

Abstract

AbstractArsenic poisoning is a global problem. It is known that groundwater in Bangladesh and West Bengal predominantly contains As(III) and concentrations of Fe(II) which are often too low for removal of arsenic in optimum quantities. To eliminate arsenic from drinking water, several basic methods such as coagulation, adsorption, ion exchange, filtration, membrane processes, are reported. To deal with this issue on a small to large scale, we present a novel approach to remove arsenic and iron from water by constructed soil filter (CSF).In CSF, As (III) is oxidized to As(V) by media via natural oxidation and subsequently, arsenic is co‐precipitated with iron. Here water containing arsenic, iron, and phosphate is passed through the CSF media at the rate of 100 ml/min. Results show a mean residence time of 8.6 min and a holdup of 1.85 l. Results of six runs show that with initial As(III) of 300 µg/l and iron concentration of 5–10 mg/l, residual arsenic levels below 10 ppb and residual iron < 0.30 mg/l in water can be achieved.In CSF, no chemicals are needed for the oxidation of As(III) to As(V). The oxidation takes place due to the presence of various oxides such as iron, manganese, aluminum, and the microbial diversity in the media of soil bioreactor. Such a novel technology is also applied for purification of water and wastewater. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.