Demineralised water is used in the industry as a raw material for the production of all kinds of products and as boiler feed water. Different techniques, ranging from low to high degree of purification, are used.
The choice of technology depends mainly on the raw water source and the desired final water quality. With high conductivities such brackish and seawater, membrane technologies such as ultrafiltration, reverse osmosis and a possible polishing step with electrode ionisation are preferred.
When starting from lower conductivities, it is preferable to apply ion exchange by means of a cation filter, anion filter and possibly a mixed bed as post-treatment.
Most industries such as textiles, food or the automotive industry use low pressure steam and boiler feed water with a conductivity of less than 5 microS/cm. The (petro) chemical sector makes use of high pressure steam and the associated ultrapure water with a conductivity that is often lower than 0.5 microS/cm.