The water consumption increases at high speed under the effect of the demographic growth and the agricultural and industrial development. This water consumption involves a significant and increasing quantity of wastewater. These untreated rejections generally are poured in receiving environment (lake, river, sea, etc.), causing harmful effects on the environment. This study aims to evaluate quantitatively and qualitatively urban water of the commune of Zeralda situated at the west (30 km) of Algiers. This water is rejected without treatment in the sea. This study has been to investigate in a first time to the parameters of pollution which influence the biological treatment of water. Among these parameters, we have determinate, pH, water-air temperature, MES, COD, BOD5, turbidity, conductivity, etc. The results of the analysis of physical and chemical parameters of pollution showed that their content exceed widely the standards of rejection [1-2]. In a second time, we have tested a biological treatment by language. This study is based on the analysis of organic matter and nutritive substances in the aqueous phase. The obtained results showed an important increase of the dissolved oxygen and 97, 94.5 and 79.2% for turbidity, NH4+ and PO43- respectively. After the obtained results this effluent can be treated, recycled and developed what constitutes an adequate solution to cure the problems of pollution, it will be able thus to safeguard the quality of the natural environment.