Anaerobic decomposition
Breakdown of organic matter by microorganisms in the absence of oxygen.
Example
Buried food waste can decompose this way and generate methane.
The catch
Temperature, moisture and material composition affect production rates.
Related terms
Methane, Anaerobic digestion, Biogas, Biomethane, Composting, Destruction efficiency
In more depth
Anaerobic decomposition, explained.
Anaerobic decomposition is the reason a landfill keeps producing methane for decades after the last lorry has left. Different groups of microbes break organic matter down in stages, and in the final stage organisms called methanogens release methane and CO₂. The same chemistry runs in wetlands and inside the stomachs of cattle.
Control decides whether it does harm. In a landfill without gas collection, it feeds landfill gas that seeps into the atmosphere. Engineers run the same process deliberately in sealed tanks, where it goes by the name anaerobic digestion and the gas becomes fuel. Keeping oxygen in the mix, as composting does, steers breakdown towards CO₂. A 'biodegradable' label therefore says little about climate effect once the item is buried.