Index >> Waste Water Microbiology >> Anion Exchangers

Anion Exchangers - Anion exchangers are usually synthetic ammonia derivatives. They are used to produce demineralised water for laboratory and other specialized uses as well as boiler feed water.

Typical anion exchanger has an exchange capacity of about 800gm equivalents / m3 and requires about 6 equivalents regenerant / equivalent exchanged.

Ion exchange materials are used in units similar to pressure filters. It is also possible to combine anion and cation resins in a single mixed-bed unit. Ion exchange plants are associated with certain problems. If the feed water contains suspended matter they may tend to coat the surface of the exchange medium and reduce its efficiency.

Water with an acceptable level of nitrate for dsistribution can be obtained by mixing a high nitrate source with another source containing little or no nitrate. If this type of blending is not possible, ion exchange technique can be used to remove nitrates since they occur as anions in solution.

However conventional anion exchangers are not selective for nitrate ions and their exchange capacity may be utilized for the removal of other anions. Nitrate exchangers with high specificity have been developed and available for use.

The advantage of ion exchange treatment is that no sludge is produced. However, after the exhaustion of the ion exchange capacity, the material has to be regenerated. This gives rise to a concentrated waste stream of the original contaminant.