EDI(Electrodeionization)is a revolutionary water treatment technology ,tiis a membrane filtration and desalination technology that skillfully combined the electrodialysis technology and ion exchange technology together ,which is high-tech ,green and eco-friendly technology. EDI equipment uses the RO outlet water as feed water .The resistivity of RO outlet water is normally 40-2us/cm(25C),and the resistivity of EDI outlet water can normally reach 18MΩ.cm(25C).According to the application of deionization water and the setup of the system ,EDI outlet water can meet the requirements for resistivity of 1-18MΩ.cm(25C). The advantages of EDI equipment are continual water production ,no acid and alkali regeneration,unattended operation ,etc.It is gradually replacing the mix bed as the fine treatment equipment .Due to its environmentally friendliness and ease of use ,EDI equipment has been accepted by more and more people and widely used in pharmaceutical ,electronic,electricity,and chemical industry.Its existence is a revolutionary progress of water treatment equipment ,which marked the water treatment industry finally entered into green industry.