Study on fluoride reduction in artesian well—water from electrodialysis process

Abstract

The possibility of removing fluoride from potable water from artesian wells to reduce the concentration of fluoride International Standard Methods (l.5 mg l −1), has been investigated. Many methods have been used to remove excessive fluoride from drinking water such as chemical adsorption, chemical precipitation, ion exchange and physical removal [reverse osmosis (RO) and electrodialysis process (ED)] because it causes harmful effects such as dental and skeletal fluorosis. In this paper two ion-exchange membranes have been examined for ED. The Selemium AMP® anionic membrane (Asahi Glass Co.) and photo-polymeric anionic membrane (MZA™) were tested in an experimental apparatus of a mini-ED cell having two acrylic compartments. The AMP® membrane, with 0.1 A dm −2 current density, removed 69% of the fluoride anion and, with 0.7 A dm −2, removed 97% of the fluoride anion. The MZA™ membrane removed 40% with that current density, without pretreatments. The analytical method for determining the fluoride anion, in every step of the electrodialysis process, was the Ion Analyzer Chromatographic System (DX-80 Dionex with conductivity detector). The results have shows the possibility of using the ED process to remove fluoride from water from artesian wells, thereby improving the quality the potable water in this region.