Electrochemical Defluoridation

Details of present/Existing Technology, Shortfall/Technological gaps in the existing technology

Presently two technologies, based on (I) alum precipitation and (ii) activated alumina adsorption are known to have been field tested.

The shortfall with alum precipitation are (I) lack of proper supply of the raw materials in the village level, (ii) lack of knowledge at the user’s end in proper dosing, (iii) generation of higher quantity of sludge compared to electrochemical defluoridation.

The disadvantages with activated alumina are (I) adsorption of fluoride at specific pH range only needing pre-and post- pH adjustment of water (ii) Regeneration generates concentrated fluoride solution, causing disposal problems and (ii) reducing adsorption efficiency of the activated alumina with increasing number of usage-regeneration cycle.

Approach adopted in new technology to evade technological gap in the exiting one: Electrochemical Route

Advantages

• No addition of chemicals
  
• No need to pre-and-post-treatments
  
• Low volume of sludge
  
• Units can be designed for any capacity
  
• Units are designed for specific locations and fluoride content of water. But can be operated with varying fluoride concentrations by slightly altering the operating parameters.
  
• The electrochemical reactor occupies less floor space.
  Operator friendly
  
• Requires less elective energy 0.3 to 0.6 Kwh/1000 lit.

Brief description

The basic principle of the process is the adsorption of fluoride with freshly precipitated aluminium hydroxide, which is generated by the anodic dissolution of aluminium or its alloys, in an electrochemical cell. The process utilises 0.3 to 0.6 Kwh of electricity per 1000 litre of water containing 5 to 10 mg/litre of fluoride. The anode is continuously consumed and need to be replenished. The process generates sludge at th rate of 80-100 gm per 1000 litres (on dry basis).

Constraints in Technology

Electricity is the essential raw material. In places where electricity supply is not available, suitable solar panels can be installed.

Applications: Drinking water

Technology Transfer Assistance Offered: Know-how, Consultancy, Prototyping, Training

Extent of Commercialisation: Seeking to license or sell this innovation

Contact for more information:

Director
Central Electrochemical Research Institute (CECRI),
Karaikudi -630 006,
Tamil Nadu, India