In anaerobic digestion, organic matter is degraded by a microbial population in the absence of oxygen and producing methaneMethane is a colourless, odourless flammable gas which is the main constituent of natural gas. It is the simplest member of the alkane series of hydro... and carbon dioxide (= biogasAnaerobic digestion More) and a solid residue that can be composted in a subsequent step without practically releasing any heat. The biogasAnaerobic digestion More can be treated in a Combined Heat and Power Plant (CHP), producing electricity and heat, or can be upgraded to bio-methane [14] [bM 06/09]