Simultaneous Removal of Heavy Metals from Surface Water by Physico-chemical Treatment Process

J. P. Choudhury, M. A. Hashim and K. B. Ramachandran

Abstract
Simultaneous removal of heavy metals, arsenic, lead, and chromium from contaminated surface water by coagulation and flocculation using ferric sulfate, alum and lime was studied. The method was effective provided arsenite (As III) was oxidized to arsenate (As-V); hexavalent chromium (Cr-VI) was reduced to trivalent chromium (Cr-III) and the contamination level of the heavy metals were below 200 μg l–1. When they were around 2000 μg l–1, further treatment with activated carbon was necessary to bring down the metal contamination level below 50 μg l–1, which is the World Health Organization (WHO) limit for recycle and reuse of water. pH significantly influenced the removal efficiency. Details of treatment processes are discussed.

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Keywords
Surface water, heavy metal removal, physico-chemical treatment, activated carbon