Waste Water Treatment by Unconventional Adsorbents

Fluoride is a major pollutant of groundwater globally. Adding to the problem is the issue of reduced ‘portable water’ availability. The fluoride content in water bodies and ground water is further increased by effluent discharge from factories that work with fluoride and its compounds as the major raw material and from municipal bodies. Fluoride consumed is limited amounts id protective for the dentition and the bones. The healthy or acceptable limits of fluoride range from 0.8 to 1.2 mg/L of water. Levels exceeding 1.5 mg/L start impacting the human health adversely. Fluorosis, a disease characterized by mottling of the dentine enamel and ligaments coupled with neurological complications, has crippled many individuals. The problem is especially pronounced in countries like India and China. Various treatment methods have been devised to remove fluoride from water. Initially chemical methods were used to treat water. With advancement in technology, several newer and better techniques emerged. Few of them are coagulation, membrane filtration and ion exchange. These methods, though highly effective, are very costly. Developing countries like India cannot afford such techniques. The attempt to find more cost effective ways ended with the discovery of adsorbents to remove fluoride. Efforts are now being made to find the best adsorbent that falls within the budgets of our pockets and is effective in removing the excessive fluoride. Studies are conducted to assess the efficacy of naturally available adsorbents like activated carbon, agricultural wastes and even red laterite soil.