Electrodeionization (EDI)

EDI is a water treatment unit, composed of ion exchange membranes and resins, which continuously regenerate ion exchange resins using direct current.

Principle of demineralization

Ions in feed water can be removed by ion exchange resins placed between anion and cation exchange membranes.

Principle of regeneration

By constantly applying direct current voltage to cathode and anode installed above and below EDI, direct current flows in ion exchange resins (feed water). Ions trapped by ion exchange resins divide into anion and cation, and begin to move toward respective electrodes.
Ions attracted by electrodes move to brine side which is separated from feed water by ion exchange membrane, and are continuously discharged to the outside of the system as brine waste water.
Since regeneration is conducted at the same time as pure water production process in this way, it is possible to produce pure water of 10-18MΩ・cm without using chemicals.

Applications

By using as substitute for a mixed bed ion exchange system, it is effective for reducing the environmental load without the use of chemicals.