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Relative significance of factors influencing DXAA formation during chloramination
The influence of natural organic matter (NOM) characteristics and reactivity, pH, chlorine‐to‐nitrogen (Cl2:N) ratio, disinfectant residual concentration, and bromide concentration on dihaloacetic acid (DXAA) formation during chloramination was studied in several diverse water sources. Analysis of variance (ANOVA) over a broad variety of experimental conditions usually pointed to pH as being the most significant factor in DXAA formation, followed by bromide concentration. A shift in speciation to the bromine‐substituted species occurred as the bromide concentration increased and the pH decreased. In general, the DXAA molar yield will not increase over the range of Br‐ or dissolved organic carbon (DOC) ratios typical of practice; however, a source water experiencing a large increase in bromide concentration may exhibit an increase in the DXAA molar yield. DXAA formation decreased as the Cl2:N ratio decreased, and ANOVA analysis also indicated that it was the next most significant contributor to DXAA formation after pH and bromide concentration. Temperature and chloramine residual also affected DXAA formation but were much less influential than the aforementioned factors. In addition, NOM in the hydrophilic fraction was more reactive in forming DXAA than NOM in the hydrophobic fraction. The effectiveness of treatment, which can have a significant effect on DXAA formation, is largely related to overall DOC removal, although preferential removal of more reactive NOM fractions also may contribute to reduction of DXAA formation.
Relative significance of factors influencing DXAA formation during chloramination
The influence of natural organic matter (NOM) characteristics and reactivity, pH, chlorine‐to‐nitrogen (Cl2:N) ratio, disinfectant residual concentration, and bromide concentration on dihaloacetic acid (DXAA) formation during chloramination was studied in several diverse water sources. Analysis of variance (ANOVA) over a broad variety of experimental conditions usually pointed to pH as being the most significant factor in DXAA formation, followed by bromide concentration. A shift in speciation to the bromine‐substituted species occurred as the bromide concentration increased and the pH decreased. In general, the DXAA molar yield will not increase over the range of Br‐ or dissolved organic carbon (DOC) ratios typical of practice; however, a source water experiencing a large increase in bromide concentration may exhibit an increase in the DXAA molar yield. DXAA formation decreased as the Cl2:N ratio decreased, and ANOVA analysis also indicated that it was the next most significant contributor to DXAA formation after pH and bromide concentration. Temperature and chloramine residual also affected DXAA formation but were much less influential than the aforementioned factors. In addition, NOM in the hydrophilic fraction was more reactive in forming DXAA than NOM in the hydrophobic fraction. The effectiveness of treatment, which can have a significant effect on DXAA formation, is largely related to overall DOC removal, although preferential removal of more reactive NOM fractions also may contribute to reduction of DXAA formation.
Relative significance of factors influencing DXAA formation during chloramination
Pope, Phillip G. (author) / Martin‐Doole, Melanie (author) / Speitel, Gerald E. Jr. (author) / Collins, M. Robin (author)
Journal ‐ American Water Works Association ; 99 ; 144-156
2007-09-01
13 pages
Article (Journal)
Electronic Resource
English
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