Fluoride removal from water by adsorption using crop wastes.

Abstract

Lack of access to safe drinking water is a major concern due to negative health effects experienced by people in many parts of the world. The quality of such waters is mainly affected by pollutants from natural and anthropogenic sources when they get incorporated in the water sources. These pollutants are either organic or inorganic species. Among the inorganic pollutants are fluorides. Continuous consumption of high concentrations of fluoride ions leads to their accumulation in the body tissues which causes dental fluorosis, skeletal fluorosis and other non-skeletal disorders. These health effects are irreversible and the only way to overcome them is by removing fluoride from water. Several methods for the removal of fluorides in water have been proposed, most of which rely on the use of biomaterials and bone char. In such processes, the adsorbents become loaded with the pre-concentrated pollutants leading to disposal problems. This report reviews on the use of modified or activated crop wastes as adsorbents followed by their subsequent application on the removal of fluoride ions from water. Fluoride occurs naturally in our environment but we consume it in small amounts. Exposure can occur through dietary intake, respiration and fluoride supplements. The most important factor for fluoride presence in alimentation is fluoridated water. When the recommended limit of fluoride by WHO is 1.5 mg/L, in some parts fluoride levels are as high as 35 mg/L. Major problems associated with fluoride remediation are lack of cheap adsorbent to remove fluoride content in water for some communities. Hence, development of community-based defluoridation unit is needed with a technique which is cost-effective, technologically simple in operation while being able to keep the fluoride level in permissible limits. On the basis of extensive investigations, different researchers have developed simple and economical domestic defluoridation processes.