Electro-deionization makes it possible to combine the advantages of the ion exchange and membrane technologies.
Electro-deionization (EDI) is the most advanced method of the finishing water purification. It allows to discard ion-exchange purification on the mixed-resin bed (mixed-bed polisher). The amount of the resulting concentrate does not exceed 10%.
EDI combines two technologies: electrodialysis and ion exchange. An EDI unit can be generally described as an electrodialysis unit with gaps between the membranes filled with ion-exchange resins (cation and anion exchange resins).
During operation the resins absorb ions from the water and regenerate due to applied voltage. In this case the resins act not as an ion-absorbing “vessel” but rather as high-speed “tunnel” enabling the transportation of ions to the reject compartment.
In order to control the quality of dimineralized water the water treatment units are equipped with analysis monitors that tell electrical conductivity, pH, sodium content in the finished product.