Drinking water treatment plants using a surface water source encounter significant concentrations of natural organic matter (NOM) in that water. High NOM concentrations become problematic when reactions with chlorine during the chlorination/disinfection process form disinfection by-products (DBPs). Two of the most common DBPs that form as a result of this reaction are trihalomethanes (THMs) and haloacetic acids (HAAs). THMs and HAAs are both proven to be carcinogenic to humans. As a result, the US Environmental Protection Agency (USEPA) has set maximum contaminant levels for THMs to 80 ppb and HAAs to 60 ppb). The removal of NOM prior to chlorination is thus a critical step in avoiding DBP formation and granular activated carbon (GAC) is an efficient and cost effective adsorbent for NOM removal.
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