In potable water treatment, the volume of granular activated carbon (GAC) per filter is a major issue, both in commercial agreements and in filter design and operation. Once exhausted, the GAC is typically regenerated by thermal reactivation.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/gac-potable-water-treatment
[2] http://admin.indiaenvironmentportal.org.in/category/journal/everything-about-water
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-treatment-technology
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-resources