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Monochloramine Loss Mechanisms in Tap Water
Author(s) -
Zhang Qianyi,
Davies Evan G. R.,
Bolton James,
Liu Yang
Publication year - 2017
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143017x14902968254421
Subject(s) - chloramine , tap water , chemistry , chloramination , chlorine , water treatment , natural organic matter , reaction rate constant , environmental chemistry , organic matter , environmental engineering , kinetics , organic chemistry , environmental science , physics , quantum mechanics
Chloramination has been widely applied for drinking water disinfection, with monochloramine (NH 2 Cl) the dominant chloramine species. However, under neutral pH, NH 2 Cl can autodecompose and react with chemical components in drinking water, thus decreasing disinfection efficiency. In tap water, the NH 2 Cl loss rate can be influenced by temperature, pH, Cl/N molar ratio, the initial NH 2 Cl concentration, and the natural organic matter (NOM) concentration. A good prediction of NH 2 Cl loss can assist in the operation of drinking water treatment plants. In this research, a kinetic rate constant )and a reactive site fraction (S = 0.43 ± 0.06) for the reaction between free chlorine released from NH 2 Cl autodecoposition and tap water NOM were derived from a kinetic model to predict the NH 2 Cl loss under various conditions. A temperature‐dependent model was also developed. The model predictions match well with the experimental results, which demonstrates the validity of the model and provides a convenient and accurate method for NH 2 Cl loss calculations.