Electrodeionisation (EDI)

EDI combines ion-exchange resin and an electric field to remove the ions that remain after reverse osmosis. The current keeps the resin regenerated continuously, so the unit produces ultra-pure water without acid or caustic regeneration. It runs continuously rather than in service and regeneration cycles, which keeps the output steady.

EDI is a polishing step. It needs feed water that is already low in salts, hardness and chlorine, which is exactly what RO permeate is. Placing it after RO keeps the EDI modules stable and gives a continuous supply of high-purity water.

There are no acid or caustic tanks to store, no regeneration downtime and no regeneration wastewater to neutralise. Output quality stays steady, which suits boiler feed and process water that must not vary. Operators mainly check the RO feed quality, the electrical supply and the product conductivity.

From the flow, the quality of the RO permeate feeding it and the purity you need. Tell us the application and, if you have it, the existing RO data through the quote form. If there is no RO yet, AFG designs the RO and EDI stages together so they match.