Granular activated carbon (GAC) adsorption is well-established for controlling regulated disinfection by-products (DBPs), but its effectiveness for unregulated DBPs and DBP-associated toxicity is unclear. In this study, GAC treatment was evaluated at three full-scale chlorination drinking water treatment plants over different GAC service lives for controlling 61 unregulated DBPs, 9 regulated DBPs, and speciated total organic halogen (total organic chlorine, bromine, and iodine). Plants represented a range of impacts, including algal, agricultural, and industrial wastewater. This study represents the most extensive full-scale study of its kind and seeks to address the question of whether GAC can make drinking water safer from a DBP perspective. Overall, GAC was effective for removing DBP precursors and reducing DBP formation and total organic halogen, even after &gt;22,000 bed volumes of treated water. GAC also effectively removed preformed DBPs at plants using pre-chlorination, including highly toxic iodoacetic acids and haloacetonitriles. However, 7 DBPs (mostly brominated and nitrogenous) increased in formation after GAC treatment. While these DBPs are highly toxic, the total calculated cytotoxicity and genotoxicity for the GAC treated waters was still lowered by 32-79% (across young-middle-old GAC). Pre-chlorination further reduced DBP concentrations and calculated toxicity.

Does GAC with chlorination produce safer drinking water? Comprehensive evaluation of chlorinated, brominated, iodinated, and nitrogenous DBPs at full scale plants

2019 Spring National Meeting

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