Vol. 4, Issue 3, Part C (2018)

Abstract: Fluoride is often described as a double-edged sword as inadequate ingestion is associated with dental caries, whereas excessive intake leads to dental, skeletal and soft tissue fluorosis which has no cure. Fluoride in water derives mainly from the dissolution of natural minerals in the rocks and soils with which water interacts. The problem of excessive fluoride in drinking water has engulfed many parts of the world, and millions of people rely on groundwater with concentrations above the World Health Organization (WHO) guideline value of 1.5 mg/L. In India, endemic fluorosis is thought to affect 65 million people. Rajiv Gandhi National Drinking Water Mission was set up to control fluorosis with a plan to overcome the problem. Nalgonda technique, Prasanti technology using activated alumina, UNICEF in India using household based defluoridation, KRASS defluoridation process, Delfuoridation based on ion exchange mechanisms, Fluoride removal by IISc method at Kolar, Karnataka are examples of defluoridation methods used in various field programs in India. The main techniques of defluoridation that have been investigated with varying degrees of success include adsorption, precipitation/coagulation, ion exchange and membrane processes. Many chemical, indigenous and herbal materials are used along with this. Precipitation is the well-established method and most widely used method, particularly at community level. Adsorption can be done with locally available adsorbent materials with high efficiency and cost effectiveness. Ion Exchange removes fluoride up to 90-95% and retains the taste and color of water intact.