Fluoride contamination, consequences and removal techniques in water: a review

Abstract

Fluoride contamination has created a drinking water crisis globally. At low concentrations, its presence is essential; however, it becomes toxic to human beings upon consumption of more than 1.5 mg L⁻¹ in mainly contaminated drinking water due to geochemical reactions and geological or anthropogenic factors. To better understand the toxicity of fluoride, in this study, we examine the recent research on the possible negative consequences of excess fluoride on diverse species. A high fluoride concentration in drinking water cause skeletal fluorosis and long-term kidney, brain, thyroid, and liver damages. This review also focuses on the different techniques for the defluoridation of water, such as electro-coagulation, adsorption, membrane processes, etc., and compares their adsorption capabilities under various situations, while their changes in the literature are reviewed. Furthermore, we present the advantages and disadvantages of different methods and conclude that each technique has shortcomings, with no single approach fitting all aspects. The condition of water pollution with fluoride and recently created technology to remove fluoride from water is evaluated, although research on fluoride contamination of water resources has been reviewed in the literature. Alternatively, this study also examines fluorosis mitigation strategies in the global and Indian settings and existing physicochemical and biological mitigation approaches. Also, the research and development results in fluoride clean-up are reviewed. Specifically, the following topics will be covered in this review: (1) fluoride contamination status, (2) consequences of fluoride contamination in drinking water on human health, and (3) current defluoridation technology.