Demineralization cartridge exhausted
If the capacity of your demineralization cartridge (VE-cartridge) is exhausted, i.e. it is no longer supplying demineralized water, this is at first a normal process. The ion exchanger contained in the demineralization cartridge is a so-called mixed bed resin and consists of a strongly acidic cation exchanger and a strongly basic anion exchanger. The demineralization cartridge can be reprocessed as part of the so-called ion exchanger regeneration, i.e. the load is removed again from the mixed bed resin and the mixed bed resin is returned to its original form and the capacity of the demineralization cartridge is restored. This means that the demineralization cartridge is ready for use again and can achieve a typical conductivity value of < 0.1 µS/cm from city water demineralization, ideally connected in series after the 2nd demineralization cartridge. However, if the time is missed, the demineralization cartridge is overrun.
For ion exchanger regeneration, the demineralization cartridge is combined in a central regeneration station for mixed bed resins in a so-called pool regeneration with other resins from the same application (city water demineralization), so-called blending. Ideally, the two fractions cation exchanger and anion exchanger from the mixed bed resin are completely separated during mixed bed resin regeneration and each regenerated separately in a two-column technique with hydrochloric acid and sodium hydroxide solution. The two fractions are then mixed together again and filled back into the delivery containers, i.e. the actual demineralization cartridge, and the depletion of the demineralization cartridge is thus reprocessed.
The process can basically be carried out with all ion exchangers and demineralization cartridges. A typical capacity loss of around 20% can be observed during the first regeneration, but this value remains largely stable during subsequent regenerations. However, after some time, approx. 4-7 years, the anion exchanger loses its functional groups. This is a typical wear and tear process that cannot be prevented. It is therefore necessary to rejuvenate the pool of the combined resins during regeneration by adding a defined quantity of new mixed bed resin to ensure consistent quality.
However, individual components are so strongly bound to the ion exchanger that regeneration is no longer possible. In this case, the capacity of the exchanger decreases and can no longer be reprocessed during regeneration; in this case, a resin change or resin replacement is required.
There are also a number of contaminants that can cause permanent damage to the exchanger, such as strong oxidizing agents, greases, oils or substances of the same density as ion exchangers. In these cases, a separate circuit of different exchangers or an additional filtration stage is often required to reduce the effect. In any case, replacing mixed bed resins from a demineralization cartridge is only necessary in very rare cases in municipal water demineralization.
Do you have further questions about when a demineralization cartridge is exhausted or about subsequent ion exchanger regeneration? Please feel free to contact us.
