314-318The fluoride concentration in ground water is
increasing at an alarming rate. Poor ground water recharge, excessive
consumption of water and other geological factors contribute to this effect.
Conventional reverse osmosis (RO) membrane system has failed because fluoride
concentration in permeate is not consistently below 1 mg/L. Moreover, the
reject stream of the RO process containing higher fluoride concentration is
left untreated. A treatment method has been devised with an objective to reduce
fluoride concentration to less than 1 mg/L from fluoride contaminated water
using calcium carbonate pretreatment and reverse osmosis. Also a passive
adsorption system to treat the reject stream of membrane process has been
developed wherein the fluoride concentration in the final effluent is below
ambient concentration. This combined system can be used to treat fluoride
contaminated water without generating secondary wastes