METHANE FERMENTATION METHOD

PURPOSE:To permit economization of chemicals and omission of forming stages by heating liquid contg. org. materials in an alkaline or acidic state and chemically decomposing the same partly by blowing air or the like thereto. CONSTITUTION:Liquid contg. org. materials is introduced into a pretreating tank 11, and is heated under atmospheric pressure under alkalinity or acidity at >=50 deg.C. Part of the org. materials are chemically decomposed by blowing an oxidative gas such as air, oxygen or ozonized air thereto. The entire volume of the liquid is fed into a methane forming tank 12, where gases contg. methane are formed and separated biochemically in the presence of methane forming bacterium groups under anaerobic conditions. Thereafter the whole volume of the liquid is fed into the 1st sludge concentrator 13 where the liquid is separated to a liquid part and a sludge part. The liquid part is fed to a treating device 14 for waste liquid. Part of the sludge part is returned to the tank 12 and the balance is fed to an acid forming tank 15 where the same is decomposed biochemically.