Hydrogen sulfide (H2S) gas typically is formed in water collection systems that are conducive to creating septic conditions. In general, septic conditions occur when bacteria use all of the available oxygen while decomposing organic matter in water for energy. Pipes with low velocities encourage the growth of anaerobic bacteria in a slime layer coating the pipes. These bacteria reduce sulfur compounds such as sulfate (SO4), thereby producing sulfides. Sulfur compounds compounds occur naturally in water.
Under anaerobic (septic) water conditions, sulfides cannot be oxidized. Therefore, they combine with hydrogen to produce hydrogen sulfide gas, creating the "rotten egg" odor associated with septic water.
Sulfate-Reducing Bacteria (SRB) are one of the main causes of Microbiologically Influenced Corrosion (MIC).
Good control of SRB will avoid the formation of H2S and extend the operational life of the system and greatly reduce the incidence of microbiological problems.