What gases are produced in anaerobic sludge digesters?

Anaerobic sludge digestion is carried in the absence of oxygen. It is considered economical as it does not require any aeration system. It takes place in four steps, hydrolysis, acidogenesis, acetogenesis and methanogenesis. Hydrolysis breaks it into small molecules by dissolving into solution. Acidogenesis results in the further breakdown of the remaining components by acidogenic (fermentative) bacteria. Simple molecules created through the acidogenesis phase are further digested by acetogen to produce largely acetic acid, as well as carbon dioxide and hydrogen. The final step is methanogenesis where the methanogens convert it into methane, carbon dioxide, and water. So, the correct answer is option B.