Bio gas plants
In general it is said that there are two types of biogas plants, Landfill- and sewage gas plants. Landfill gas is formed during the natural degradation of organic material in a landfill. The degradation (fermentation) in a landfill requires a long period of time. It is generally said that the main part of the organic material is degraded and the main part of the gas is formed after a period of 20 years. Sewage gas is formed during a controlled degradation (fermentation) process and after 20-30 days the main part of the organic material has been degraded. In a biogas plant the produced biogas is separated from the remaining substance after fermentation for further transport to a utilizer.
Except from gas also a nutritious rest product, is produced in a sewage gas plant. This rest product is commonly called bio manure and can after approved quality control be used as manure on fields.