ELECTROCHEMICAL TREATMENT FOR REMOVAL OF ARSENIC FROM DRINKING WATER

Abstract

Millions are affected worldwide by arsenic, toxicity due to intake of arsenic contaminated drinking water. Orissa, Bihar, Bengal, Andhra Pradesh in India and most part of Bangladesh are the worst affected region. Arsenic toxicity induces both acute and chronic health effects causing skin ailments and cancer of various organs. WHO has prescribed the limit of arsenic in drinking water to be less than 10 ppb. In India also, the current limit of 50 ppb in drinking water is being lowered to 10 ppb. In the present work, various arsenic removal technologies studied in literature have been reviewed. Electrochemical treatment of drinking water was found to be and effective and viable technology for arsenic removal from drinking water. Arsenic with an oxidation state of +3, As (III) is found to be more toxic than +5 oxidation state, As (V). Most of the treatment technologies perform effectively when treating water containing As (V). The electrochemical treatment of Arsenic containing water renders As(III) to be oxidized to As (V), and thereafter the formation of a complex with ferric hydroxide which results in its removal in the form of a settleable solid. Batch experiments were performed on millipore purified water containing arsenic with 10 mg 1-1 concentration. Batch and continuous experiments were also performed for arsenic containing tap water. All the experiments conducted were carried out on synthetically prepared drinking water samples. Effect of such parameters as initial pH, conductivity of water and current density were examined. The sludge was subjected to scanning electron microscope; X-Ray diffraction and thermogravimetric analysis to understand sludge characteristics and arsenic complexation with iron. The experimentation draws major conclusions on the electrochemical treatment of water containing arsenic and proves its benefits over the other available technologies