Indian Journal of Chemical Technology, Vol.10, No.1, 87-95, 2003
Removal of arsenic from water by coagulation treatment using iron and magnesium salt
Arsenic in ground water assumes a predicament of global dimension. Among the various methods of removal of arsenic from contaminated water, coagulation-filtration route has been examined in details covering effect of pH, coagulant type and its dose, and initial arsenic load in water. A set of batch experiments were conducted in the laboratory to investigate arsenic removal efficiency from spiked aqueous solution as well as a few ground water samples collected from the affected zone of West Bengal (India). The removal kinetics of aqueous arsenic spiked samples with iron/magnesium salt as coagulants were studied to assess the feasibility for the use in the arsenic removal in water treatment plant, and a plausible kinetic behaviour in their removal process has been discussed. A comparative performance efficiency for iron salt in contrast to magnesium salt as coagulant has been examined to establish the superiority of iron system Increase in background ionic species such as Cl-, NO3- and SO42- in test solution with iron system have been performed in which Cl- and NO3- ions showed no effect on the efficiency of arsenic removal, while pronounced lowering effect has been observed in case of SO42- ion. This investigation suggests that for community supply of arsenic free water, the proposed protocol-coagulation with iron salt and subsequent filtration hold promise.