Estimation of haloacetonitriles formation in water: Uniform formation conditions versus formation potential tests

Kanan, Amer
Karanfil, Tanju
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Science of the Total Environment
To date, several studies have used formation potential (FP) tests to examine the presence of HAN precursors in water and wastewater. However, given the decomposition of HANs with time at elevated free chlorine levels, FP test results do not provide meaningful results.Weconducted side-by-side FP and uniform formation condition (UFC) experiments to demonstrate that, in order to obtain practical, meaningful, and representative information about HANs formation and their precursors during chlorination, it is important to conduct experiments and report results under UFC [or simulated distribution system (SDS)] conditions. The results confirmed higher HAN formation under UFC than FP tests during chlorination of the tested two surface water and three wastewater effluent samples, indicating HAN decomposition at high chlorine conditions of FP tests. In addition, thewell reported ratio (~10%) of HAN/THMfrom previous studies was more consistentwith the UFC results but was lower than 10% in the FP results. On the other hand, HAN formation during chloramination of the same samples were lower under the UFC than FP conditions. Furthermore, FP tests under both chlorination and chloramination resulted in lower bromine substitution factor. We concluded that reporting results of HANs FP tests are not representative, and future studies should focus on UFC or distribution system specific (SDS) experiments for chlorination. However, chloramination FP tests may still provide some information about the HAN precursors in waters.
HANs formation from five different chlorinated water sources were higher under UFC than FP tests. • Chlorination FP tests do not provide meaningful information for HAN precursors in water samples. • UFC (or SDS) chlorination test should be used for a better estimation of HAN precursors in water. • Higher HANs formed under FP test compared to UFC test during chloramination. • Chloramination FP tests may be used for determining HAN precursors in water reactive to chloramine.
Disinfection by-products , Haloacetonitriles , Formation potential test , Uniform formation conditions test , Chlorination Chloramination
Kanan A, Karan T (2020) Estimation of haloacetonitriles formation in water : Uniform formation conditions versus formation potential tests. 744:1–6.