Deactivation of wastewater-derived N-nitrosodimethylamine precursors with chlorine dioxide oxidation and the effect of pH


UZUN H. , Kim D., Karanfil T.

SCIENCE OF THE TOTAL ENVIRONMENT, cilt.635, ss.1383-1391, 2018 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 635
  • Basım Tarihi: 2018
  • Doi Numarası: 10.1016/j.scitotenv.2018.04.148
  • Dergi Adı: SCIENCE OF THE TOTAL ENVIRONMENT
  • Sayfa Sayıları: ss.1383-1391

Özet

In this study, the effect of chlorine dioxide (ClO2) oxidation on the deactivation of wastewater (WW)-derived N-nitrosodimethylamine (NDMA) precursors was investigated under various conditions (i.e., ClO2 application pH, dose and contact time). At pH 6.0, decreases in NDMA formation potentials (FPs) or occurrences (under uniform formation conditions [UFC]) were relatively low (<25%) with ClO2 oxidation regardless of WW-impact. A negative removal was also observed after ClO2 oxidation in some of the non-impacted waters. However, NDMA FP removals were significant (up to similar to 85%) under the same oxidation conditions in WW-impacted waters at pH 7.8. This indicates that the majority of WW-derived NDMA precursors can be deactivated with ClO2 oxidation above neutral pH. This was attributed to the better oxidative reaction of ClO2 with amines that have lone pair electrons to be shared at higher oxidation pH conditions. In addition, relatively short oxidation periods with ClO2 (i.e., <= 10 min) or low Ct (concentration x time, similar to 10 mg * min/L) values were sufficient for the deactivation of WW-derived NDMA precursors. ClO2 oxidation was effective in freshlyWW-impacted waters. Natural attenuation processes (e.g., sorption, biodegradation, etc.) can change the reactivity of WW-derived NDMA precursors for oxidation with ClO2. The effect of ClO2 on the removal of THM precursors was low(<25%) and independent of oxidation conditions. Given the low formation of regulated THMs and HAAs, ClO2 oxidation presents a viable option for the simultaneous control of NDMA and regulated DBP formation during water treatment, especially for utilities treating WW-impacted water sources. (C) 2018 Elsevier BV. All rights reserved.