To allow ammonia generated in a biodegradation process of organic waste by anaerobic microorganisms not to inhibit the stable generation of biogas.
In a reaction, organic substances are biodegraded inside a fermenter 1 stirred in an airtight state by the anaerobic microorganisms, and converted into the biogas 11 containing methane and carbon dioxide gas. In the reaction, an anaerobic digestive inside the fermenter 1 is extracted and filtered by a precision membrane 3 for passing through ammonia molecules. When ammonia concentration in the filtrate is a prescribed threshold value or higher, the filtrate is fed to an ammonia emission tank 8 and ammonia is removed. When the ammonia concentration therein is the threshold value or lower, an anaerobic digestive not passing through the precision membrane 3 is also returned to the fermenter 1.
MATSUSHITA KATSUTERU
SUNAHARA HIROSHI
