Control of odor removal and air pollution in wastewater treatment plants has become critical because of the negative impacts of invasive pollutants that are no longer limited to the working environment of sewage treatment plants, but extend to nearby residential areas when appropriate weather conditions are present. Residents of the city of Al-Nasiriyah in Iraq suffer from the the foul odors from the Jazeera Wastewater Treatment Plant in the city of Al-Nasiriyah, located in the province of Dhi Qar in southern Iraq. Therefore, efforts must be intensified to reduce the risks they pose to the ecosystem and the serious damage to human health. In this study, a biofilter system was designed to remove the odors emitted (hydrogen sulfide and ammonia gas) from the conventional activated sludge Al-Nasiriyah-Jazeera wastewater treatment plant. The biofilter odor removal system is designed for inlet screw pumping station, screening station, aerated grit chamber and parshall flume inlet. The result of the design of the biofilters, which meets the environmental requirements of Iraq according to the law of environmental protection No. 27 of 2009 and its instructions No. 3 of 2011 was the inlet screw pumping station (volume of buildings to be treated – 400 m3, number of changes per hour >5 n/h, design flow rate to be captured and treated – 2000 m3/h, H2S removal efficiency >98%, volume of substrate media – 24 m3, height of surface media – 1.4 m, and overall dimension (length – 8.9 m, height – 2.27 m, width – 2.13 m)), as well as the preliminary treatments screening station, aerated grit chamber and parshall flume inlet (volume of buildings to be treated (each biofilter) – 400 m3, number of changes per hour – 12 n/h, design flow rate to be captured and treated (each biofilter) – 5000 m3/h, H2S removal efficiency >98%, volume of substrate media – 60 m3, height of surface media – 1.4 m, and overall dimension (length 10.6 m, height 2.27 m, width m 2.13 m)).