Electrodeionization of water (EDI) is a water treatment method based on the use of electrostatic forces to remove ions from water. EDI is a continuous and chemical-free process for removing ionized and ionizing substances from feed water using direct current. Electrodeionization is commonly used to purify (polish) reverse osmosis permeate (RO) and is an alternative or replacement for traditional ion exchange in the H-OH form.
The EDI process involves the passage of water through special cells consisting of two electrodes (anode and cathode) separated by an ion exchange membrane. Under the influence of the ion exchange membrane’s electric field, cations move to the anode and anions to the cathode. These ions are then removed from the solution on the surface of the electrodes due to the electric charge they do not have. With the right current and voltage, ion exchange membranes have a constant regeneration process.
