Question

what is the composition of biogas

Answer 1

The composition of biogas varies depending upon the substrate composition, as well as the conditions within the anaerobic reactor (temperature, pH, and substrate concentration).[13] Landfill gas typically has methane concentrations around 50%. Advanced waste treatment technologies can produce biogas with 55%–75% methane,[14]which for reactors with free liquids can be increased to 80%-90% methane using in-situ gas purification techniques.[15] As produced, biogas contains water vapor. The fractional volume of water vapor is a function of biogas temperature; correction of measured gas volume for water vapor content and thermal expansion is easily done via simple mathematics[16] which yields the standardized volume of dry biogas.

In some cases, biogas contains siloxanes. They are formed from the anaerobic decomposition of materials commonly found in soaps and detergents. During combustion of biogas containing siloxanes, silicon is released and can combine with free oxygen or other elements in the combustion gas. Deposits are formed containing mostly silica (SiO
2) or silicates (Si
xO
y) and can contain calcium, sulfur, zinc, phosphorus. Such white mineral deposits accumulate to a surface thickness of several millimeters and must be removed by chemical or mechanical means.

Practical and cost-effective technologies to remove siloxanes and other biogas contaminants are available.[17]

Answer 2

Biogas plant works on organic wastes. It is primarily a mixture of methane (CH4) and inert carbonic gas (CO2).
However the name “biogas” gathers a large variety of gases resulting from specific treatment processes, starting from various organic waste - industries, animal or domestic origin waste .