About landfill gas and its composition

Old landfill
Landfill Gas (LFG) is composed of a number of gases that are present in large amounts and others in very small amounts (the trace gases). The principal gases are produced from decomposition of the organic fraction of MSW (Municipal Solid Waste). Some of the trace gases, although present in small quantities, can be toxic and could present risks to public health.

Typical Landfill Gas composition

When the gas is pumped from the landfill under controlled conditions by a degassing plant, air can be aspired into the degassing system with consequent dilution of the gas with air. The main gases present in a landfill under working conditions have the following average concentrations:

- Methane


40 - 50 Vol. %

- Carbon dioxide


35 - 45 Vol. %

- Nitrogen (from air)


5 - 15 Vol. %

- Oxygen (from air)


1 - 3 Vol. %

- Water vapour




Minor components and traces in the Landfill Gas (LFG).

Typically following trace gases are part of Landfill Gas:

Sulphides, mainly Hydrogen sulphide H₂S  100 - 500 mg/m3 
Mercaptanes (unpleasant odour)   << (very little)
Chlorinated organic compound HCI 20 - 100 mg/m3
Fluorinated organic com-pounds (e.g. Freons) FI
10 -   50 mg/m3
VOCs such as halogenated hydrocarbons HHC
and aromatic halogenated hydrocarbons HAHC
………… mg/m3
Non-Methane organic compounds
………… mg/m3
0 -  50 mg/m3
Heavy metals (cadmium, zinc, lead, mercury, etc.)
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