Water Treatment-Water demineralization

Demineralised water is used in many different industrial processes in several industries: pharmaceutical, chemical,  food, etc.  Water is demineralised by treatment with two different resin containing columns : an acid cationic exchange resin, and a basic anionic exchange resin.

The type of resin to be used should be defined by the resin producer depending on the requirements.

These ion exchange resins need to be regenerated periodically depending on water and resin characteristics. The products which regenerate these resins are caustic soda for the anionic exchange resins and hydrochloric acid for the cationic ones.

Regeneration processes must be defined by the resin producer but, in general, three steps can be mentioned:

1. Backwash rinsing with water to eliminate fines and any particle coming from the water flow,
2. Injection of a 5% hydrochloric acid solutions, 
3. Rinsing with about 3 times the resin volumes to eliminate the hydrochloric acid in two progressive phases, a slow one to eliminate the greater part of the hydrochloric acid and a fast one to eliminate the last residue.

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