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. The Unit can deployed in the fluoride affected regions of India through Govt./ NGO support.

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