EDI, or Electrodeionization, is called contact deionization device. EDI design combines two mature water purification technologies - electroosmosis and ion exchange deionization. With lower energy consumption, soluble salts can be removed without adding chemicals for regeneration, and high purity water of several megaohms/cm can be produced continuously and stably. At the same time, compared with the traditional process, it is more compact in structure, small in floor area, low in water production cost, free of incidental pollution, modular design, simple in installation, operation and maintenance.