Anion exchange

"The chemical process where negative ions of one chemical are preferentially replaced by negative ions of another chemical. In water treatment, the net effect is the removal of an unwanted ion from a water supply. For example, some water treatment facilities or homeowners install an anion exchange system to remove nitrate (NO3–) from their water supplies." (Virginia Polytechnic Institute and State University, n.y.)


Virginia Polytechnic Institute and State University. "A Glossary  of Water-Related Terms", by Brian Benham. Publication 442-758