Fluorine is a common element that does not occur in the elemental state in nature
because of its high reactivity. It accounts for about 0.3 g/kg of the Earth’s crust and
exists in the form of fluorides in a number of minerals, of which fluorspar, cryolite
and fluorapatite are the most common.
Exposure to excessive consumption of fluoride over a lifetime may lead to increased likelihood of bone fractures in adults, and may result in effects on bone leading to pain and tenderness. Children aged 8 years and younger exposed to excessive amounts of fluoride have an increased chance of developing pits in the tooth enamel, along with a range of cosmetic effects to teeth.
http://www.who.int/water_sanitation_health/dwq/chemicals/fluoride.pdf
You van go for Bio-sorption procedure for low cost water defluoridation
Coagulation method and Activated alumina methods are commonly used for fluoridation of water. The results are good and acceptable. The detail process is available in literature. .
Adsorption is low cost method for remove excess levels of F. preparing activated carbon from some local low cost materials is a good option. Carbon prepared from bone char is very efficient.
Dear Dr. Prakash,
I have shared the following write-up to some researchers. You can go through the same.
A brief account on fluoride removal (based on literatures):
Various techniques and materials were explored throughout the world for defluoridation of groundwater. The techniques can broadly be classified into four categories:
Adsorption technique, Ion-exchange technique, Precipitation technique, and Other techniques, which include electro chemical defluoridation and reverse osmosis.
Materials used as defluoridation agents in these four techniques are:
Adsorption: Carbon materials, Activated Alumina, Magnesia, Tricalcium phosphate, Calcite, Hydroxy apatite, Wood, Lignite, Activated char coal, Fish bone char, Processed bone, Nut shells, Avaram bark, Paddy husk, Coffee husk, Tea waste, Jute waste, Coir pitch, Fly ash, Bauxite, Serpentine
Ion-exchange : a) Anion exchange resins- NCL poly anion resin, Tulsion A27, Lewatit-MIH-59, Amberlite IRA-400, Deacedodite FF-IP, Waso resin-14, Polystyrene. b) Cation exchange resins: Defluoron-1, Defluoron-2, Carbion.
Precipitation: Lime, Alum, Lime & Alum (Nalgonda technique), Alum flock blanket method, Poly Aluminium Chloride (PAC), Poly Aluminium Hydroxy Sulphate (PAHS), Brushite.
Others: Electrochemical method (Aluminium electrode), Electro dialysis, Electrolysis, Reverse Osmosis.
The basic characteristics of an ideal defluoridation process are the following:
o Cost-effective
o Independent of input fluoride concentration, alkalinity, pH, temperature
o Easy to handle/operate by rural population - the major sufferer
o Not affect the taste of water
o Not add other undesirable substances (eg. Aluminum) to treated water
Defluoridation can be introduced at two organizational levels; as household defluoridation for consumption of single household members and as community defluoridation for the public use in a village.
The defluoridation processes available today are not totally successful. Nalgonda and Krass processes for defluoridation have some merits.
This is for your kind information that at CSIR-CMERI, Durgapur we are working on the defluoridation of groundwater. We have already developed a process (adsorption technique) for defluoridation and filed a patent in April, 2016.
We have also designed and developed a 'Domestic Defluoridation Unit' for reducing the fluoride content in water. In addition to the removal of fluoride, the unit also arrests other common contaminants found in the groundwater. This unit is suitable for domestic purposes in the fluoride affected rural areas.
Specifications
· No electricity
· No chlorine, no bromine, no iodine used
· No running water required
· Flow rate: 5 L / hour
· Adsorbent life (proposed): ~2000 L
· Storage capacity: 18 L
Techno- Socio-Economic analysis
· Adsorbent replacement cost: Rs. 600/-
· Maintenance cost/month: 150/- (~500 L p.m.)
· The commercial filtration unit addressing the defluoridation of water for domestic purposes is not available in the market. The developed filtration unit could be promising for commercialization.
· Unit can be deployed in the fluoride rich regions of India through Govt./ NGO support
We are conducting a research project entitled “Geochemical modelling of fluoride contamination in groundwater of the Birbhum District, West Bengal” which primarily aims to explore the origin and enrichment mechanism of fluoride in groundwater. This study has encouraged us to undertake the work on defluoridation of groundwater.
We have a plan to deploy some working models of the ‘Defluoridation Unit’ in the fluoride affected villages of Birbhum district, West Bengal.
Please give your feedback.
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