Selective exchanger system fault
Among the ion exchangers, the selective exchanger is most frequently found as a selective final exchanger in the selective exchanger system in industrial chemical-physical wastewater treatment systems or in groundwater remediation. Since changing wastewater compositions are often to be expected there, the reasons for the fault of the selective exchanger system with selective ion exchanger are also more varied.
- Outlet of the selective exchanger is higher than the inlet
The problem that the selective ion exchanger has a higher outlet than the inlet is usually either due to the fact that the pH value has sunk into the regeneration area of the ion exchanger, or another regeneration agent (e.g. methanol) has come into contact with the ion exchanger, or that the exchanger has already reached the end of its capacity and thus according to the Ion exchanger selectivity also releases substances again. This is the case, for example, if an unexpectedly high load has reached the exchanger, e.g. because precipitation was not carried out in the preceding wastewater treatment system and therefore the selective ion exchanger was immediately fully loaded. Another reason could be, for example, that the regeneration of the selective ion exchanger (or the selective ion exchanger cartridge) has not been carried out or has not been carried out completely. If the selective ion exchanger is not fitted with a regeneration monitoring, it may be the case that the regeneration program runs without errors, but no (or not enough) regeneration chemicals have actually reached the selective ion exchanger. In this case, the ion exchanger is not or not fully regenerated and therefore only has a lower capacity. The reasons are usually that pumps or venturi nozzles are not sufficiently maintained or the chemical supply was not sufficiently filled. - Blocking of the selective ion exchanger
A common problem in industrial wastewater treatment can also be the blocking of the selective ion exchanger (see picture). A distinction must be made here as to whether it is a particle breakthrough, which is rather rare due to the typically upstream multi-layer filter, as this is usually blocked. However, finely dispersed particles can break through the typical 3-5 µm of the multi-layer filter, especially at the beginning of the loading time after a backwash. Oils and grease, which can accumulate in the regularly monodisperse selective exchanger resin (i.e. an open-pored frame structure, not a solid resin ball), can also cause problems here. However, precipitation in the selective ion exchanger is a more frequent problem. As the selective ion exchanger shifts the pH value within the cartridge during operation as intended, individual elements can enter the precipitation area and thus precipitate in the exchanger. A typical example would be alkaline dissolved aluminum, which forms an aluminum monoblock when it precipitates in the ion exchanger, which is virtually cannot be removed anymore. Another example is high sulphate concentrations in exchangers in the Ca form; gypsum is formed as a monoblock in the exchanger. Other problematic substances in the wastewater stream are manganese and tin. Sometimes blockages in the exchanger can be removed by backwashing or be loosend up chemically and rinsed out again, but sometimes a resin change is required. - Biology on the selective exchanger
Depending on the selective exchanger system, the occurence of biology on the exchanger cannot be completely prevented. Biology enriched in the selective exchanger (especially the red algae) can grow into the regularly monodisperse selective exchanger resins (i.e. an open-pored frame structure, not a solid resin ball) and thus block it permanently. During regeneration, even with hydrochloric acid and caustic soda, it is possible that the biology can no longer be completely removed. In this case, a loss of capacity of the ion exchanger is to be expected.
Do you have other problems with your selective ion exchanger or do you need external maintenance for your selective ion exchanger? Please do not hesitate to contact us.