What many toxic and harmful gases can be produced by sewage treatment

Wastewater treatment facilities can produce many toxic and hazardous gases such as methane (combustible gas), hydrogen sulfide, carbon monoxide and carbon dioxide. These gases come from a variety of sources, such as cesspools, pumping stations, aeration tanks, sludge digestion tanks, deodorization plants and treatment plants. Aeration and sludge digestion, for example, are usually high-risk areas for biogas generation These biogas produced from sludge contain hazardous substances such as methane, hydrogen sulfide and carbon dioxide. In addition to being highly explosive, methane causes a decrease in oxygen concentration, which increases the risk of asphyxiation. On the other hand, hydrogen sulfide has a special odor at low concentrations (0.0047 ppm), which is extremely easy to identify; however, when the concentration exceeds 150 ppm, human olfactory nerves will not be able to smell it due to damage, thus masking its true presence, and even if hydrogen sulfide reaches a lethal concentration of 800 ppm, the workers will not be able to smell it, posing a fatal danger. Since biogas is extremely flammable, and the biogas produced during sludge digestion can be used to generate electricity, it will be very dangerous if it leaks out of the digester and is likely to cause an explosion.