The Removal of As(V) From Drinking Waters by Coagulation Process Using Iron Salts

Abstract

In this study arsenate [As(V)] removal from drinking water by coagulation process was investigated. Ferric chloride (FeCl <inf>3</inf>.6H <inf>2</inf>O) and ferrous sulfate (FeSO <inf>4</inf>.7H <inf>2</inf>O) were used as coagulant. The effects of major operating variables such as coagulant dose (1-30 mg/L) and pH (5.5-9.5) were investigated. Ferric chloride and ferrous sulfate were found as effective and reliable coagulant due to required dose, residual arsenate and coagulant concentration. Optimum pH values for maximum arsenate removal for ferrous sulfate and ferric chloride were found as 8 and 7.5. The arsenate removal efficiency decreased at neutral and acidic pH values for Fe(II) and at the high acidic and high alkaline pH for Fe(III). It was found that the increase of coagulant dose caused a substantial increase in the arsenate removal. But above a certain ferric chloride and ferrous sulfate dosage, the increase in arsenate removal was not significant. Ferric chloride and ferrous sulfate dose above 8 mg/L slightly increased arsenate removal.