Electro Deionisation (EDI)

Electro Deionisation (EDI) treatment is based on the simultaneous application of two processes – membrane separation and Ion Exchange. Electro deionisation is a very efficient as well as environmentally-friendly process for the treatment of water and often used to replace conventional Mixed Bed Ion Exchange Units.

Electro Deionization (EDI) is a continuous, chemical-free process of removing ionized and ionizable species from feedwater using DC power. EDI is typically used to polish RO Permeate and is alternative to conventional mixed bed Ion Exchange Process.  EDI eliminates the need to store and handle hazardous chemicals used for resin regeneration in mixed beds. And since electricity is EDI’s only consumable, this method of permeate polishing does not produce a hazardous waste stream.

Water enters the EDI module, where an applied voltage induces ions to move through the resins and across the membranes. These ions are collected into concentrate streams which can then be sent to drain. The deionized product water from an EDI module can then be used directly or undergo further treatment. Due to the intrinsic nature of an EDI device, the resins are continuously regenerated by the current and are never exhausted

Advantages of EDI

Chemical-free regeneration, No need to store or handle hazardous acid and caustic
There is no waste neutralization or disposal issues.
There is no “breakthrough" of ions as happens in conventional ion exchange operations
The quality of the water remains at a constant high level of purity.
The electric field also provides a bacteriostatic environment inside of the EDI cell, inhibiting the growth of bacteria and other organisms.
Has significantly lower operating costs than conventional ion exchange processes.
Has significantly smaller footprint than conventional ion exchange processes

Disadvantages of Electro Deionisation (EDI)

High capital cost
Must be fed with Reverse Osmosis
Fouling & Scaling of Membranes


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