Identifying Causes and Controls for Intermittent Nitrate Release from Granular Activated Carbon

Inorganic contaminants, such as nitrate, arsenic, and hexavalent chromium, are weakly adsorbed onto granular activated carbon (GAC). When GAC is used to remove organic contaminants, release of inorganic contaminants has been observed. Through bench-, pilot-, and full-scale testing, this project explored the science underlying the release of inorganic contaminants from GAC. Predictive models were developed to help identify what water sources may be vulnerable to events of regulatory concern. The project also evaluated design and operational controls that utilities could implement to mitigate release events. Research Partners: California Water Service Company and Calgon Carbon Corporation. Published in 2023.