Landfill gas

Landfill gas is a complex mix of different gases created by the action of microorganisms within a landfill. Landfill gas is approximately forty to sixty percent methane, with the remainder being mostly carbon dioxide. Trace amounts of other volatile organic compounds comprise the remainder (<1%). These trace gases include a large array of species, mainly simple hydrocarbons.

Production of landfill gases

Landfill gases are the result of three processes:

The first two depend strongly on the nature of the waste. The dominant process in most landfills is the third process whereby anaerobic bacteria decompose organic waste to produce biogas which consists of methane and carbon dioxide together with traces of other compounds. Despite the heterogeneity of waste, the evolution of gases follows well defined kinetic pattern. Formation of methane and CO₂ commence about six months after depositing the landfill material. The evolution of gas reaches a maximum at about 20 years, then declines over the course of decades.