Electrodeionization (EDI) is a process for continuous demineralisation of permeate from a reverse osmosis unit. An EDI module consists of several chambers that are separated by ion-selective membranes. The chambers are filled with ion exchange resin and placed between two DC voltage electrodes.
The DC voltage applied makes the ions contained in the EDI feed water migrate to the corresponding electrode. Cations are attracted by the cathode and anions by the anode. Since the ion-selective membranes are positioned inversely, the ions are collected in the channels between the chambers and carried out of the module by a partial stream, the EDI concentrate flow.
Particular advantages of this method are uninterrupted operation without need for chemicals. These units have a very small footprint. The EDI concentrate – concentrated RO permeate – does not require neutralisation; it can be recirculated within the unit or used for other purposes.
The finished water is delivered with a conductivity of < 0.2 µS/cm, which meets most industrial water treatment standards.
Areas of use:
High-pressure steam boilers
Metal processing industry
Ultra-pure water processes
Our water treatment experts will gladly consult with you and help with the layout and sizing of your installation. WaterPro offers a range of package EDI and EDI/RO plants.