The treatment domestic urban wastewater is growing nowadays, because of the rising cost of water and because of environmental pollution, and becoming an important water source for agricultural irrigation. The aim of this study was to decrease the biological oxygen demand (BOD5), chemical oxygen demand (COD) and total Suspended solids (SS) of urban wastewater the city of Kenitra by activated sludge, in first time focusing on determining the best activated sludge pilot plant operating conditions after in order to confirm the performance of the station, a long duration of the pilot purification test was conducted. The pilot operating conditions correspond in terms of mass load to a low load are: Flow 0.5l / h; Oxygenation rate 60%; 100% recycling of the activated sludge; Aeration tank agitation 100 rev/min. Also, a sustained performance during the trial period, during which, the station operated in low mass load, producing water with BOD5, COD and SS, which is respectively (90.20%, 89. 79% et 97.67%) much lower levels in Moroccan discharge standards. The final treated wastewater could be reused water for agricultural irrigation.