In an attempt to establish a method for controlling the generation of hydrogen sulfide in wastewater force mains, we injected air into a force main, measured its effect on the level of hydrogen sulfide and organic matter, and studied pressure loss and the appropriate volume of air to inject. When air was injected, the concentration of dissolved oxygen was 1 mg/l or more at the terminal point of the force main and there was no increase of hydrogen sulfide. An experimental equation for finding the volume of air injection required to inhibit the generation of hydrogen sulfide was established. This method both inhibits the generation of hydrogen sulfide and helps to purify the wastewater. Our study on pressure loss in the two-phase flow of air and liquid confirmed that it is possible to calculate it using previously proposed models.