Impact of brominated amines on monochloramine stability during in-line and pre-formed chloramination assessed by kinetic modelling - Université de Poitiers Accéder directement au contenu
Article Dans Une Revue (Data Paper) Science of the Total Environment Année : 2018

Impact of brominated amines on monochloramine stability during in-line and pre-formed chloramination assessed by kinetic modelling

Résumé

In this study, a comprehensive kinetic model was developed and validated to predict the stability of monochloramine (NH2Cl) in presence of iodide and bromide for both pre-formed and in-line chloramination application in absence of organicmatter. pH had the greatest influence on the stability of NH2Cl in waters containing bromide. For in-line chloramination, the NH2Cl decay over 3 days was only 10% for pH 9 and 58% for pH 7 (400 mu gBr(-)/L and 3 mgCl(2)/L). Bromide also greatly affected the stability of NH2Cl by influencing the formation and speciation of the halamines produced during chloramination. In-line chloramination is commonly used since the pre-chlorination oxidises iodide to the non-toxic iodate. During pre-chlorination, brominated organics are formed from reaction between bromine and dissolved organic matter (DOM). In the case of the Colorado River DOM, 26% of the bromine was sequestered in only 4 min, and therefore not available to form brominated amines during chloramination. Following ammonia addition, an immediate loss of oxidant was observed in water containing bromide at pH 7 and 8. This is due to the reaction between NHBrCl and NHBr2, and the auto-decomposition of NHBr2 formed from NH2Br. Once NHBr2 was consumed, NHBrCl accumulated and then slowly decayed. Thereafter, the total oxidant concentration decayed slowly due to the auto-decomposition of NHCl2 and the reaction between NHBrCl and NHBr2. In the presence of DOM, the CHBr3 concentration increased, while the CHCl3 concentration (formed during pre-chlorination) was constant during chloramination, indicating that brominated- amines may continue to form disinfection by-products (DBPs).
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Dates et versions

hal-04437198 , version 1 (04-02-2024)

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Citer

Sébastien Allard, Keith Cadee, Rachel Tung, Jean-Philippe Croué. Impact of brominated amines on monochloramine stability during in-line and pre-formed chloramination assessed by kinetic modelling. Science of the Total Environment, 2018, 618, pp.1431-1439. ⟨10.1016/j.scitotenv.2017.09.281⟩. ⟨hal-04437198⟩
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