FLUORIDE ION: AN INEXPLICABLE HYDRO TOXICANT

Excessive concentration of fluoride in drinking water has deleterious effects on human health and causes fluorosis which progresses gradually and becomes a crippling malady in the long run. It affects young, old, poor, rich, rural, and urban population and has attained a very alarming dimension. The Rajasthan state has extreme climatic and geographical condition due to which it suffers of both the problems- quantity and quality of water. In most part of the state groundwater is either saline or having high nitrates and fluoride content. Groundwater is the major source of drinking water and amounts to be over 94% of the drinking water demand. Groundwater and its level is deeper year-byyear due to over exploitation. As the water table is receding more and more water sources are becoming prone to higher fluoride concentration. The pattern and prevalence of fluorosis in human population are determined by a number of epidemiological factors like water chemistry, demographic and nutritional profile of the community and high mean annual temperature of the area. Alum is used as the coagulant in the treatment process. It has several disadvantages like high sludge volume, residual aluminium, wearing effects on the treatment structure. Therefore, an alternative to alum for defluoridation assumes importance. Although number of defluoridation methods are available, but the Nalgonda Technique has been mostly adopted in Indian context. The main problem of the Nalgonda Technique is the residual Aluminium in treated water which at times is found to be higher than the permissible limit, i.e. 0.2mg/L. In present study we aim to reduce the use of Alum by bringing down the fluoride level firstly with Moringa oleifera (MO) seeds powder and then using Alum later on. For reduction from low fluoride levels less Alum will be required as compared to reduction from high fluoride levels and hence, we would be able to reduce the residual aluminium in the treated water. Apart from solving the residual aluminium problem, coagulation by MO seeds solves the sludge volume problem also as it produces less amount of sludge for the same amount of removal in comparison to Alum.