Experts in water quality analysis for over 25 years

High levels of arsenic in tubewell drinking-water in West Bengal, India, have been linked to arsenical dermatosis and skin cancer. A laboratory lime softening test was carried out to remove arsenic from groundwater samples collected from one of the affected areas. At a lime dose of 1250 mg/l and pH 11.8, maximum removal was 90% whereby arsenic concentration was reduced from 0.68-0.70 mg/l (arsenic (III) 0.59-0.60 mg/l) to 0.07 mg/l. With powdered bituminous coal additive (2 g/l), residual arsenic level below the WHO guideline level of 0.05 mg/l was achieved at a lime dose of 800 mg/l and pH 11.5. The magnesium-hydroxide precipitate played a more significant role in removing arsenic, particularly arsenic (III) than calcium carbonate.

With thanks to the IRC, Netherlands