Electrolytic Defluoridation Unit
Water fluoridation is the controlled addition of fluoride to a public water supply to reduce tooth decay. Sometimes there is a excess fluoride in water and defluoridation is needed when the naturally occurring fluoride level exceeds recommended limits.
A 1994 World Health Organization expert committee suggested a level of fluoride from 0.5 to 1.0 mg/L (milligrams per litre). Bottled water typically has unknown fluoride levels, and some domestic water filters remove some or all fluoride.
Methods to Remove Fluoride from Water
Boiling Water will concentrate the fluoride rather than reduce it. But Freezing Water does not affect the concentration of fluoride. Boiling or freezing will not reduce the fluoride in the water.
Fluoride can help prevent cavities, but as the amount taken in increases it can also harm teeth (dental fluorosis) and bones (skeletal fluorosis).
The most serious effect of fluoride is its accumulation in bones from long-term excessive exposure, which can lead to skeletal fluorosis and bone fractures.
The intake of excessive amounts of fluoride can lead to dental fluorosis, preventing the normal maturation of the enamel, but only during the period of tooth development in children, up to 6–8 years old.
Recently I visited CSIR technofest 2010 showcased by Council of Scientific & Industrial Research, New Delhi, at India International Trade Fair in New Delhi, the Capital of India. In this technofest, I have seen a technology "Electrolytic Defluoridation Unit" which was developed by NEERI (National Environmental Engineering Research Institute), Nagpur, under the aegis of CSIR, New Delhi, India.
This is simple and most efficient process for defluoridation of water using the in-situ generation of poly hydroxy aluminium species by passing Direct Current (DC) through aluminium plates.
Fluoride removal will be done by poly – hydroxy aluminum species produced by electrolysis using aluminum electrodes. It produces potable water with palatable taste as against the other chemical treatment methods. Quantity of sludge produced is much less (60-70%) than conventional treatment methods. Simultaneous reduction in nitrate and bacterial contamination in treated drinking water.
NEERI has developed the plant which run on solar energy / electrical energy & is based on electrolytic process for removal of Fluoride from ground water. The process is free from chemical. The basic principle of process is absorption of fluoride with freshly precipitated aluminum hydroxide which is generated by the anodic dissolution of aluminum in an electrochemical cell.
Electricity is the main raw material & hence wherever electricity is not available a suitable solar panel can be installed. The anode is continuously consumed & needs to be replenished.
I came to know that this technology has already been transferred and Installed at Balod (C.G) in India.
Below links may be useful for more details and information