SUMMARY
The objective of the study is the optimization of physico-chemical processes in order to treat water of Babar dam, located in the Wilaya of Khenchela (Northeast Algeria). Beforehand, some data are presented on the Babar dam and the characteristics of the watershed that may affect the quality of the water. The study is particularly focused on determining optimum conditions of application of the coagulation-flocculation with aluminum sulphate and chlorination steps that are essential in the clarification phase and disinfection of drinking water. Samples of raw water from the dam have been laboratory tested and have shown that their quality was average overall but nevertheless characteristic of surface water. The chlorination tests of raw water resulted in significant chlorine consumption potentials that could be related to the presence of inorganic and organic elements among the most reactive with respect to chlorine. The reduction of the ultra-violet absorbance indicates a fraction of the organic material could be degraded in aliphatic structures that may lead to potentially toxic trihalomethanes formation. The coagulation-flocculation and settling tests, carried out according to the Jar Test protocol, demonstrated that this optimized step resulted in good pollution removal efficiencies and values of quality parameters in accordance with the potability standards. The combination of clarification and post-chlorination has resulted in a significant decrease in chlorine demand and therefore a lower reactivity to chlorine. The combination of clarification and post-chlorination resulted in a significant decrease in the chlorine demand and therefore a lower reactivity vis-à-vis the chlorine, which can reduce the possibility of formation of toxic halogenated organic compounds.