In this study, a lab scale different activated sludge configurations methods were used to treat a municipal wastewater from effluent of; primary sedimentation tank of Al-Rustamiya wastewater treatment plant located near Baghdad city to remove organic load, nitrogen and phosphorus from the period of 15 July 2012 to 22 May 2013.Biological treatment systems were conventional activated sludge (CAS) , extended aeration , anaerobic-anoxic-aerobic( A2O) , anoxic-aerobic (MLE) and anaerobic –oxic(A/O). During the operation periods, the average removal efficiency of BOD5, COD and TSS is 81.9, 77.7 and 85.8 respectively regardless of the fluctuation in influent quality. In addition the results show removal efficiency of ammonia, nitrate, nitrite and phosphorus with ranges (61-85.8), (34-81.7) , (35-81.4) (32.3-85.54) % respectively. The biological treatment systems produced high quality effluent which can achieve the Iraqi limitations of rivers maintenance for all measured parameters.