@article{cuthbertson_kimura_liberatore_knappe_stanford_summers_dickenson_maness_glover_selbes_et al._2020, title={GAC to BAC: Does it make chloraminated drinking water safer?}, volume={172}, ISSN={["0043-1354"]}, DOI={10.1016/j.watres.2019.115432}, abstractNote={Biological activated carbon (BAC) is widely used as a polishing step at full-scale drinking water plants to remove taste and odor compounds and assimilable organic carbon. BAC, especially with pre-ozonation, has been previously studied to control regulated disinfection by-products (DBPs) and DBP precursors. However, most previous studies only include regulated or a limited number of unregulated DBPs. This study explored two full-scale drinking water plants that use pre-chloramination followed by BAC and chloramine as the final disinfectant. While chloramine generally produces lower concentrations of regulated DBPs, it may form increased levels of unregulated nitrogenous and iodinated DBPs. We evaluated 71 DBPs from ten DBP classes including haloacetonitriles, haloacetamides, halonitromethanes, haloacetaldehydes, haloketones, iodinated acetic acids, iodinated trihalomethanes, nitrosamines, trihalomethanes, and haloacetic acids, along with speciated total organic halogen (total organic chlorine, bromine and iodine) across six different BAC filters of increasing age. Most preformed DBPs were well removed by BAC with different ages (i.e., operation times). However, some preformed DBPs were poorly removed or increased following treatment with BAC, including chloroacetaldehyde, dichloronitromethane, bromodichloronitromethane, N-nitrosodimethylamine, dibromochloromethane, tribromomethane, dibromochloroacetic acid, and tribromoacetic acid. Some compounds, including dibromoacetaldehyde, bromochloroacetamide, and dibromoacetamide, were formed only after treatment with BAC. Total organic halogen removal was variable in both plants and increases in TOCl or TOI were observable on one occasion at each plant. While calculated genotoxicity decreased in all filters, decreases in overall DBP formation did not correlate with decreases in calculated cytotoxicity. In three of the six filters, calculated toxicity increased by 4-27%. These results highlight that DBP concentration alone may not always provide an adequate basis for risk assessment.}, journal={WATER RESEARCH}, author={Cuthbertson, Amy A. and Kimura, Susana Y. and Liberatore, Hannah K. and Knappe, Detlef R. U. and Stanford, Benjamin and Summers, R. Scott and Dickenson, Eric R. and Maness, J. Clark and Glover, Caitlin and Selbes, Meric and et al.}, year={2020}, month={Apr} }
 @article{zhang_maness_cuthbertson_kimura_liberatore_richardson_stanford_sun_knappe_2020, title={Treating water containing elevated bromide and iodide levels with granular activated carbon and free chlorine: impacts on disinfection byproduct formation and calculated toxicity}, volume={6}, ISSN={["2053-1419"]}, url={https://doi.org/10.1039/D0EW00523A}, DOI={10.1039/d0ew00523a}, abstractNote={We evaluated the efficacy of granular activated carbon (GAC) adsorption for mitigating formation of chlorine disinfection byproducts (DBPs) in water with a wide range of bromide (20–1000 μg L−1) and iodide ( 30 000 bed volumes). In the GAC influent, total organic bromine increased from 10 to 84% of TOX as bromide levels increased from 20 to 1000 μg L−1. Dissolved organic carbon (DOC) removal by GAC increased the bromide-to-DOC (Br/DOC) concentration ratio in GAC effluent relative to influent. As a result, bromine incorporation into DBPs increased after GAC treatment, especially at early GAC service times and low bromide levels. Total organic iodine was 50%) in all samples despite the quantification of 70 DBPs targeted in this study, highlighting the need to assess toxicity associated with unknown DBPs.}, number={12}, journal={ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Chuhui and Maness, J. Clark and Cuthbertson, Amy A. and Kimura, Susana Y. and Liberatore, Hannah K. and Richardson, Susan D. and Stanford, Benjamin D. and Sun, Mei and Knappe, Detlef R. U.}, year={2020}, month={Dec}, pages={3460–3475} }