Fluoride Removal From Drinking Water Using Electrocoagulation-electroflotation Process

Fluoride has both beneficial and harmful effects on human health. An appropriate concentration of fluoride in drinking water for daily ingestion is required to prevent dental cavities, but long-term consumption of water that contains more than a suitable level of fluoride can cause teeth mottling and even bone disease. There are 29 nations in the world suffering such a problem to different extent that their drinking water contains more fluoride than the norm recommended. Especially in China, more than 260 million people are drinking the water with high concentration of fluoride. Therefore, it is necessary to explore effective and economical defluoridation processes.Nowadays, the main defluoridation processes include adsorption, ion exchange, reverse osmosis, chemical precipitation and electrodialysis. Though these processes can remove fluoride from water effectively, they are complex in operation, difficult in equipment maintaining, and high in treatment cost. Additionally, the ion exchange, reverse osmosis, and electrodialysis can not only remove fluoride, but also remove the beneficial ions present in water simultaneously. These disadvantages limit the wide application of the currently available defluorideation processes mentioned above in industry.The electrocoagulation-electroflotation process is a new technique in water and wastewater treatment. This process has been successfully used to remove fluoride from wastewater. The basic principles are: aluminum electrodes sacrifice themselves to form Al³⁺ ions by electrolysis; the Al³⁺ ions then hydrolyze and react with F^- ions to form Al(OH)_3-xF_x floc. Meanwhile, tiny H₂ and O₂ bubbles generated in electrolysis help to float the Al(OH)_3-xF_x floc, leading to effective fluoride removal from wastewater. The electrocoagulation-electroflotation process is characterized by compact equipment, simple operation, and low operating cost.In this study, the electrocoagulation-electroflotation process was utilized to remove fluoride from drinking water. The main research objectives are to investigate the key...