Disinfection byproduct formation potential (DBPFP) tests can be used to indirectly assess removal of disinfection byproduct (DBP) precursors in water treatment processes. Based on Standard Methods 5710, a DBPFP test requires sample waters to be buffered at pH 7 and dosed such that the chlorine residual (CR) is between 3-5 mg/L as Cl2 after a 7-day reaction period at 25�C in the dark. As such, an excess of disinfectant is applied under a standard set of reaction conditions, such that DBP formation is presumably limited by the precursor concentrations. However, the impact of certain conditions, such as the concentration of DBP precursors and CR, is not fully understood for many DBPs, potentially clouding assessment and improvement of DBP-precursor removal processes. This presentation will focus on the impact of disinfectant type, CR, and pH on the formation of trihalomethanes (THMs), haloacetonitriles (HANs), and total N-nitrosamines. The results of this study show that the true DBPFP, i.e. maximum DBP concentrations, is rarely achieved at a CR between 3-5 mg/L as Cl2 and depends on other factors, such as the concentration and nature of the DBP precursors and the disinfectant type and pH. The results can be leveraged to help improve various DBP-precursor removal processes (e.g., sorption, coagulation, oxidation) and guide development of a more robust DBPFP test.

Improving assessment of precursors of THMs, HANs, and N-nitrosamines in water treatment processes

248th National Meeting (2014)

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