Deionization, also known as demineralization, is a process that removes all ions from the water which produces (close-to) distilled water using resin. This ultra-pure water is typically used for laboratories, boilers, blending and so forth.
Deionization is used for polishing and is best used in conjunction with a reverse osmosis system. The cost of deionization needs to be weighed-up against equipment maintenance, operation, failures and downtime - often justifying the investment.
How deionization works
Engineered to fit
The cost ranges depending on the size and complexity of the system. You should budget from R55 000 for a small system (expected yield up to 100kL).
This is for a single-use resin and includes RO pretreatment.
Deionization uses resins to absorb the ions in the water. Two types of resins are needed namely cation and anion resins, to ensure that both positive and negative ions are absorbed.
For low volumes of water a mixed-bed, single-use resin is typically used. This resin can only filter a fixed volume (calculated on feedwater quality) before it needs to be replaced.
For high volumes of water a regenerating resin needs to be used. Each cation and anion resin is separate and regenerates using solutions of acids and alkaline.
Resin life is paramount and reverse osmosis is typically used as pretreatment to deionization. The already pure RO water has less impurities to remove and consequently extends resin life.