Which gases may sewer gas potentially contain?

Sewer gas is a mixture of gases generated by the breakdown of organic matter in sewage. The correct choice includes dihydrogen sulfide, methane, and chlorine, which are commonly associated with sewer gas.

Dihydrogen sulfide is a colorless gas known for its characteristic rotten egg smell and is produced during the anaerobic digestion of organic materials. Methane, a byproduct of the decomposition process, is significant due to its flammability and as a greenhouse gas. Chlorine, while not typically a product of sewage itself, can be present in small quantities as a result of water treatment processes.

Understanding the composition of sewer gas is crucial for safety and health concerns in waste management and plumbing systems, as these gases can be hazardous to human health and the environment. These gases can lead to toxic exposure or potential explosions in confined spaces. Thus, the correct answer reflects the real risks and components associated with sewer gas.