A Review of Defluoridation Techniques of Global and Indian Prominence

Abstract

Fluoride(F-) is the 13thmost abundant chemical element in the Earth's crust which has been widely recognised for its health benefits at low concentration but poses a serious threat to public health at very high doses. The world health organization has set the fluoride guideline limit of 1.5 mg/l in drinking water. Globally, over 260 million people drink water with high fluoride concentrations. Widespread distribution and high fluoride levels in the potablewater in most of the areas of the world has prompted substantial research and mitigation efforts to address the growing public health concerns related to fluoride contamination. With the recent advances in science, various defluoridation methods such as adsorption, ion exchange, precipitation-coagulation, membrane processes, biological defluoridation and even integrated approaches have been developed for the management of fluoride-contaminated aquatic environments. This review provides an up-to-date insight into thedefluoridation techniques developed and implemented throughout the world and highlightsthe advantages and disadvantages of each technique.The literature survey confirms that despite developing so many novel techniques for defluoridation over the years, there is still no effective fluoride removal technique that can achieve the desired results in a cost-effective and sustainable manner. Therefore, development of a commercially practical, economical, and sustainable technique is required to prevent people especially the most vulnerable from poor and developing nations (dependent on untreated water)from the hazards of fluoride contamination.

Fluoridated Water, Effects and Green Removal Techniques

“…There are two types of ion exchange resins according to the functional group that is attached to the polymer matrix. Anion exchange resins exchange negatively charged ions (like fluoride), whereas cation exchange resins exchange positively charged ions from the solution [85]. These resins have small porous beads and are insoluble in most organic solvents and water, making them suitable for fluoride removal.…”

“…Commonly used membrane-based technologies that include ultrafiltration (UF), reverse osmosis (RO) and nanofiltration (NF) are among the best available defluoridation technologies [85]. Fluoride removal efficiency using reverse osmosis is more than 99%.…”

Recovery of Al(iii) and Fe(iii) from Acid Mine Drainage using CaO and their Subsequent Use in Fluoride Removal from Water

“…To remove fluoride from water, several defluoridation methods have been devised such as electrocoagulation, adsorption, and reverse osmosis [10]. Fluorosis problems such as skeletal and dental fluorosis are brought on by drinking water with too much fluoride [11].…”

Lignocellulosic Biomass as Sorbent for Fluoride Removal in Drinking Water

“…The World Health Organization (WHO) establishes a Maximum Permissible Limit (MPL) for fluoride in drinking water of 1.5 mg/L. It estimates that water intake in concentrations above this limit represents a health threat to millions worldwide [ 3 , 4 ]. In addition, dental and skeletal fluorosis, neuronal damage, and fertility issues are recognized as health problems associated with fluoride ingestion [ 1 , 2 , 5 ].…”