Electrodeionization apparatus comprising sub-desalination chambers

An electrodeionization method for producing deionized water using an electrodeionization apparatus, wherein

• said electrodeionization apparatus comprises
• a series of desalination chambers each provided with a cation exchange membrane on one side and an anion exchange membrane provided on the other side, and filled with ion exchange materials,
• a concentrate chamber provided on either side of said desalination chamber via said cation or anion exchange membranes, and
• a pair of electrodes interposing the said assembly of desalination and concentrate chambers, and wherein said each desalination chamber is divided into two sub-desalination chambers by an intermediate ion exchange membrane provided between said cation and anion exchange membranes, said method comprising the steps of,
• supplying the water to be treated into first sub-desalination chambers and supplying the water discharged from said first sub-desalination chambers into said second sub-desalination chambers while applying a voltage between said pair of electrodes,
• supplying concentrate water to said concentrate chambers,
• concentrating the impurity ions present in the water to be treated in said concentrate water, and
• producing deionized water as water discharging from said second sub-desalination chambers.