Overview of fluoride removal from water using separation techniques

Abstract

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. • Different methods for water defluoridation have been thoroughly discussed. • Nalgonda method used in several countries has been thoroughly discussed for fluoride removal. • The merits and demerits of the defluoridazation methods are discussed. • Adsorption is most preferred separation process for defluoridation because of its low cost and high efficiency.