Overview of fluoride removal from water using separation techniques

Fluoride contamination due to natural and anthropogenic activities has become the biggest threat to human health worldwide. Geological and anthropogenic factors are responsible for contaminating groundwater with fluoride. Excess amounts of fluoride in potable water may cause irreversible demineralization of bone and tooth tissues, a condition called fluorosis, and long-term damage to the brain, liver, thyroid, and kidney. For a long time there has been a need for fluoride removal from potable water to make it safe for human use. The present paper reviews the different methods used for defluoridation, for example, coagulation-precipitation, ion exchange, membrane separation, and adsorption. Among the methods, membrane and ion exchange are not regularly used in India due to their cost and high maintenance. On the other hand, coagulation-precipitation and adsorption are mostly used in India. Nalgonda method is used in developing nations like Kenya, Senegal, Tanzania, and India for fluoride removal. Comparatively, adsorption is broadly used for defluoridation because of its low cost and high efficiency in removal. This paper also discusses the merits and demerits of the methods. It is evident from literature study that different methods show unique potential for defluoridation. The most promising adsorbents tested so far from each category of adsorbents are also highlighted. In any circumstance, there is an urgent requirement to find the practical utility of such developed methods on a business scale and to initiate a change in contamination control. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Fluoride contamination, caused by both natural and anthropogenic activities, poses a major threat to human health globally. Various methods for defluoridation such as coagulation-precipitation and adsorption are used, with India relying mainly on the former. The Nalgonda method is utilized in developing nations for fluoride removal, while adsorption is widely used due to its cost-effectiveness and efficiency.