Siloxane is a kind of polymer. Its main chain is composed of silicon atoms and oxygen atoms alternately (silicon oxygen bond), and its side chain is connected with silicon atoms, mainly including methyl, phenyl or vinyl. Because of its low flammability, low surface tension, thermal stability, hydrophobicity, high compression rate, low toxicity and many other excellent characteristics, it is widely used in detergent, cosmetics, drugs and other industries.

The siloxane in biogas mainly comes from the undissolved compounds in the anaerobic digestion process. These compounds mainly come from cosmetics, detergents, building materials, paper coatings, textiles, drugs, etc. Since these consumables are often discharged into sewage treatment plants or landfill sites, the biogas produced by anaerobic digestion of agricultural wastes and most industrial wastes generally does not contain or contains a small amount of siloxane, while the content of siloxane in landfill gas and sludge biogas is relatively high.

The content of siloxane in biogas produced by different landfill plants varies greatly. Generally speaking, the content of siloxane in biogas produced by garbage stacked for a long time is lower, and the content of siloxane in biogas produced by open landfills is higher than that of closed landfills. Because the temperature of anaerobic digestion of sludge is higher than that of landfill, the concentration of siloxane in biogas produced by anaerobic digestion of sludge is generally higher than that in Biogas of landfill.