Demineralisation by ion exchange is a method of removing dissolved solids from water.
In most industrial processes, high alkalinities and totally dissolved solid concentrations in water are inimical to various functions. Therefore, it is usually necessary to reduce the dissolved solids in the process water.
First the water passes through a cation column that is regenerated with hydrochloric acid. In this phase the cations in the water are exchanged for hydrogen ions. Then the water passes through an anion column that is regenerated with sodium hydroxide. In this phase the anions in the water are exchanged for hydroxyl ions. Together, hydrogen and hydroxyl ions form water.
AUTOMATIC MIXED BED PLANT
Applicable for polishing of demineralized water that is produced in an automatic two-column plant or in a reverse osmosis plant. Also applicable for production of moderate quantities of demineralized high-quality water direct from the waterworks.
Applicable to polishing of highly technologic water installation. Applicable to the pharmaceutical industry, hospitals, electronic industry, power stations etc.
THE MIXED BED PRINCIPLE
The plant contains a mixture of cation and anion exchangers that are regene- rated with hydrochloric acid and sodium hydroxide, respectively. When the water passes through the regenerated ion exchangers the cations and the anions are exchanged for hydrogen and hydroxyl ions, thus producing demineralized water with an extremely low conductivity.
Treatment of demineralized water with low carbonic acid content results in conductivities as low as under 0.1 µS/cm. at 10°C. This demands regenerations with demineralized water. If the silica content is to be as low as possible, it is necessary to heat the regeneration water.