BOUDRAA SARAHATTALAH ISLAM2024-03-012024-03-012015-06577-109-Mhttp://dspace.univ-khenchela.dz:4000/handle/123456789/2604The wastewater treatment has become an important problem in Algeria because of the accented demographic growth. The elimination of pollution is achieved by micro-organisms responsible for the reduction of organic matter; is the principle of the three stations that were the subject of this study: Khenchela station; Constantine and Guelma. The removal efficiency for the various parameters (MES, NH4, BOD5, ....) In the three stations is satisfactory but other equally important elements have not been considered as heavy metals and microbiology of these waste water due to the nature of the problem posed. We Recommend to future generations such approachesfrThesis