Under what conditions is hydrogen sulfide gas not produced?

Hydrogen sulfide gas is typically produced under anaerobic conditions, which is the absence of oxygen. In contrast, aerobic conditions involve the presence of oxygen, which supports the growth of aerobic bacteria that predominantly oxidize organic matter and prevent the accumulation of hydrogen sulfide. Under these aerobic conditions, sulfur compounds are usually converted to sulfates rather than being reduced to hydrogen sulfide.

This biological process is crucial in wastewater treatment, as controlling the environment to remain aerobic can help minimize the production of unpleasant odors and harmful gases like hydrogen sulfide, which is also toxic in nature. Therefore, the presence of aerobic conditions is what effectively prohibits the formation of hydrogen sulfide gas.