ELECTRO DIALYSIS: Solving Water Scarcity Applying Ion Exchange Method

Supplying potable water to the ever growing population is anticipated to be one of the major challenges in the coming future. Salt water covering more than 97% of the available water bodies on earth could be a prime source of water supply provided that it is backed up with a feasible and sustainable infrastructure.

Electro dialysis could provide for an intensive and efficient pathway for extracting pure fresh water from saltwater in coastal zones. It is a membrane process, during which ions are transported through semi permeable membrane, under the influence of an electric potential. Electro dialysis (ED) is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference. This is done in a configuration called an electro dialysis cell. It can be easily used for extracting salt just by alternating the positive and negative side of DC power generator. It doesn’t require High pressure like Reverse Osmosis system. Having a much simplified maintenance system than Reverse Osmosis, it has relatively lower long-term cost than Reverse osmosis. It costs around 0.6$/m3 of water to purify 3g/L saline water whereas the previous most effective technique Reverse Osmosis would cost around 0.68$/m3. The cost increases proportionally with the saline concentration of water. Electro Dialysis Water Treatment Plant in Netherlands is capable of producing 1492 meters cube fresh water per day.

Even though it is an economical and an efficient method, some things are to be maintained and considered while conducting this methodology. Organic matter, colloids and Silicon Dioxide are not removed by this system. Non-Charged higher molecular ions are very difficult to remove in this process, so the process is specialized for treating sea water which is rich in sodium chloride. Selection of materials of construction for membranes and stack is important to ensure compatibility with the feed stream. Desalination of sea water in coastal zones to provide for suffice amount of fresh water is an ongoing process dating back many years ago. Population being on the rise, in countries beside coastal areas, it has become a crying needs to extract fresh water from sea water in order to meet the demands of water supply. Electro dialysis provides 30-40% more efficiency than reverse osmosis with an economical, sustainable, danger free and environment friendly infrastructure. Not only will we be able to get fresh water but also huge amount of salt which could be used for industrial purposes and market supply.