Water hardness removal using wheat straw and rice husk ash

Abstract

This study examined potential of using wheat straw ash (WSA) and rice husk ash (RHA) to remove hardness of natural and synthetic water. Eight water samples (both natural and synthetic) with hardness between 236 to 580 mg/L were treated with eleven different doses of WSA and RHA ranged from 0 to 25 g ash L -1 at regular increment of 2.5 g. Water hardness, hardness removal efficiency and change in pH were measured. Hardness removal efficiency and pH of water increased with increasing doses of ash. Maximum removal was achieved at 17.5 and 22.5 g/L for WSA and RHA and further ash addition did not change the hardness. Maximum removal efficiency of WSA was 81% and RHA was 58%. Higher efficiency of WSA might be related to presence of higher concentrations of alkali metal oxide. As similar to removal efficiency, WSA also increased pH of water samples relative to RHA. The results thus indicate that locally available WSA and RHA may be an alternative technique in hardness removal process.