A master’s thesis at the College of Engineering at the University of Basrah discussed (a mathematical model of a sequential effluent reactor that treats domestic sewage using the activated sludge model number one). Created from a 500-liter collection tank and a 250-liter reactor, mixing and aeration units, a programmable control panel and other accessories, the CSBR unit has been operating for about four months with different operating scenarios to obtain the best operating conditions that correspond to our local conditions The message aims to define an effective control strategy to achieve the most operational Efficiency of an SBR plant that treats local sewage water for the city of Basra The thesis concluded that the SBR system can be used successfully to treat domestic sewage in Basra and achieve high removal rates for the pollutants that were present and with a percentage of (91, 90.3, 68) percent for each (TN, NH4_N, COD) respectively. As for the characteristics of the wastewater used, it was found that three steps are required for the reaction stage of (deoxygenated conditions / aerobic conditions / incomplete conditions
oxygen) respectively, and the life of the sludge 10 days to achieve the optimum removal rate for both COD and TN compounds.