A B S T R A C TFrom a bibliographic synthesis on the reactions that can occur during breakpoint chlorination. We carry out the stability study of produced entities under the applied conditions in the potable water production, where the pH range 6.5-8.5, and the initial weight ratio Cl/N including in 10/1-15/1 at ambient temperature. The choice of dominant species and reactions that have been taken into account must be based on data of the thermodynamics and the kinetics governed by pH and temperature. Through this selection appears a large disagreement in results of researches between the rate expressions of the kinetics and observed and even with the empirical results, especially for reaction the monochloramine formation and for equilibrium the formation-hydrolysis of trichloramine. Then, the nature of identified intermediate and the observed rate of its formation reaction were not agree in different published works, as well the possibility of destruction of the free chlorine residual by this intermediate is not confirmed yet. Through this study, we obtain a representative selected group of reactions during breakpoint chlorination process, this identified group of reactions is compared with other models of breakpoint reactions proposed in the literature, where some differences appear.

A B S T R A C TThis study is focused on the determination of added chlorine dose in low ammoniacal concentration contained in distribution pipe of drinking water. The chlorine concentration in disinfected water varies between events of lack and excess that must be regularly controlled. The chlorine transport from the inlet to the outlet of pipe is carried out in turbulent flow where the phenomena of diffusion and convection are in charge to convey chlorine and chloramines formed along the polyvinylchloride pipe. The chlorine decay is principally due to ammonia consumption in the water bulk. The chlorine demand serves to generate inorganic chloramines and the formation of an uncertain intermediate, which helps to destruct them, and the reactions series of formation-destruction are referring to Breakpoint chlorination. The set of presented reactions at Breakpoint chlorination are not clear and the observed rate constants are not similar in the researchers found in the literature. Then, their choices are not easy because they cause large differences between the experimental profiles of disinfectants concentrations taken from literature and the predicted profiles of disinfectant concentrations investigated in the present paper. The set of differential equations are resolved simultaneously by the method of finite differences. Therefore the concentrations of free residual chlorine, ammonia, monochloramine, dichloramine, trichloramine, nitrogen hydroxide and total chlorine are calculated at different points constituted the municipal pipe.