What is the major gas produced by anaerobic decomposition?

The major gas produced by anaerobic decomposition is methane. This process occurs in environments devoid of oxygen, where organic matter is broken down by microorganisms. During anaerobic digestion, bacteria decompose organic materials and release methane as a byproduct. Methane is a significant component of biogas, which can be utilized as a renewable energy source.

In contrast, while carbon dioxide is also produced during anaerobic decomposition, it is not the primary gas; rather, it occurs in smaller quantities compared to methane. Nitrogen, although present in various compounds, is not a direct product of anaerobic decomposition itself; it is often found in organic matter but does not result from the decomposition process. Hydrogen sulfide can be produced in anaerobic conditions, particularly in the presence of sulfur, but this is typically at much lower concentrations than methane and is considered a secondary product. Therefore, methane stands out as the dominant gas resulting from anaerobic decomposition.