Chloramination of nitrogenous contaminants (pharmaceuticals and pesticides): NDMA and halogenated DBPs formation
MetadataShow full item record
AbstractDisinfection with chloramines is often used to reduce the production of regulated disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). However, chloramination can lead to the formation of N-nitrosamines, including N-nitrosodimethylamine (NDMA), a probable human carcinogen. Previous research used dimethylamine (DMA) as a model precursor of NDMA, but certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. This study investigates the NDMA formation potential of several tertiary amines including pharmaceuticals and herbicides. The reactivity of these molecules with monochloramine (NH2Cl) is studied through the formation of NDMA, and other halogenated DBPs such as haloacetonitriles (HANs) and AOX (Adsorbable Organic Halides). Several compounds investigated formed NDMA in greater amounts than DMA, revealing the importance of structural characteristics of tertiary amines for NDMA formation. Among these compounds, the pharmaceutical ranitidine showed the highest molar conversion to NDMA. The pH and dissolved oxygen content of the solution were found to play a major role for the formation of NDMA from ranitidine. NDMA was formed in higher amounts at pH around pH 8 and a lower concentration of dissolved oxygen dramatically decreased NDMA yields. These findings seem to indicate that dichloramine (NHCl2) is not the major oxidant involved in the formation of NDMA from ranitidine, results in contradiction with the reaction mechanisms proposed in the literature. Dissolved oxygen was also found to influence the formation of other oxygen-containing DBPs (i.e. trichloronitromethane and haloketones). The results of this study identify several anthropogenic precursors of NDMA, indicating that chloramination of waters impacted by these tertiary amines could lead to the formation of significant amounts of NDMA and other non-regulated DBPs of potential health concern (e.g. dichloroacetonitrile or trichloronitromethane). This could be of particular importance for the chloramination of wastewater effluents, especially during water reuse processes. © 2011 Elsevier Ltd.
- Formation of NDMA and halogenated DBPs by chloramination of tertiary amines: the influence of bromide ion.
- Authors: Le Roux J, Gallard H, Croué JP
- Issue date: 2012 Feb 7
- Identification of potential nitrogenous organic precursors for C-, N-DBPs and characterization of their DBPs formation.
- Authors: Chang H, Chen C, Wang G
- Issue date: 2011 Jun
- The contribution of dissolved organic nitrogen and chloramines to nitrogenous disinfection byproduct formation from natural organic matter.
- Authors: Chuang YH, Lin AY, Wang XH, Tung HH
- Issue date: 2013 Mar 1
- Formation of NDMA from ranitidine and sumatriptan: the role of pH.
- Authors: Shen R, Andrews SA
- Issue date: 2013 Feb 1
- Occurrence of disinfection byproducts in United States wastewater treatment plant effluents.
- Authors: Krasner SW, Westerhoff P, Chen B, Rittmann BE, Amy G
- Issue date: 2009 Nov 1