De-fluoridation of Groundwater using Precipitation Method in a Region of Nagaur District, Rajasthan, India

Abstract

Safe drinking water is a human right. Groundwater is polluted by number of chemical elements which includes fluoride too. Deteriorated quality of drinking water due to high concentration of fluoride is one of the major issues in India including in the state of Rajasthan. Although various de-fluoridation methods are available, in Indian context the Nalgonda Technique and Activated Alumina has been mostly adopted. Alum is used as the coagulant in Nalgonda method. However, it has some disadvantages like high sludge volume, residual aluminium and wearing effects on the treatment structure. In Nalgonda Technique, residual Aluminium in treated water is found to be higher than the permissible limit, i.e. 0.2mg/L. Therefore, an alternative compound other than Alum for de-fluoridation assumes great importance. We aim to reduce the use of Alum in this research work. Ferric Ammonium Sulphate was used as precipitating agent for removal of fluoride ion from groundwater collected from few localities of Nagaur district of Rajasthan State. In order to remove fluoride ion from water, standard solutions of fluoride and Ferric Ammonium Sulphate of different concentrations were prepared and initial and final concentrations of Fluoride solutions were determined by Fluoride ion meter. The affinity of Ferric Ammonium Sulphate for fluoride ion was studied using different solutions as the Sodium fluoride solution containing Fluoride ion. The removal of fluoride ion increases with increasing volume of 2% and 5% solution of Ferric Ammonium Sulphate.