Removal of Fluoride From Drinking Water by Freezing Technology



Hosseini SS^{1, 2} ; Mahvi AH^{1, 3} Show Affiliations
Source: Fluoride Published:2019

Abstract

Many countries in the world are experiencing a severe water crisis with 1.1 billion people living without access to clean and safe drinking water. Fluoride is ubiquitous in nature and an excessive intake of fluoride via the drinking water results in significant health effects, particularly with exposure in utero and in early childhood. Most of the conventional methods for the removal of fluoride from drinking water in water treatment plants require high initial capital and ongoing maintenance costs. The aim of the present study was to investigate the freezing and melting process as an innovative, convenient, and low-cost technology to produce healthy drinking water for people living in areas with high drinking water fluoride concentrations. We found that the freezing and melting process had a proximate fluoride removal performance of 60% when the freezing of water with a high concentration of fluoride proceeded until 10–15% of the initial water volume was frozen. Nevertheless, in order to achieve drinking water with less than 1.5 mg/L of fluoride, from water with a high initial fluoride content, one or two re-freezing steps of the melted ice were required. In the end, it was proven that this method is able to produce enough healthy drinking water for children for households. This process could be used as a cost-effective large scale technology in the community or as a small scale method at home with a minimal capital expenditure and no need for advanced knowledge requirements. With application of liquid natural gas (LNG), solar energy, and wind power as clean and cheap energy sources, it will be possible to build large scale freezing systems for the removal of fluoride from drinking water for communities. © 2019, ISFR.