Electro Deionisation System ( EDI)

Electrodeionization (EDI) is a continuous, chemical-free process that removes ionised and ionizable species from feedwater using direct current (DC) power. EDI is commonly used to polish RO permeate and is a viable alternative to – and effective replacement for – traditional mixed bed ion exchange (IX). The use of electrodeionization eliminates the need for hazardous chemicals used in mixed bed resin regeneration to be stored and handled. Furthermore, because EDI uses only electricity, this method of permeate polishing does not generate a hazardous waste stream.The basic structure of an EDI stack is similar to that of a deionization chamber. An ion exchange resin is packed between a cationic exchange membrane and an anionic exchange membrane in the chamber. Only ions can pass through the membrane; water cannot.