NOVELTY - The methane-fermentation processing apparatus comprises an acid formation tank (1), a methane-fermentation tank (3), a separation apparatus and an aeration device. The separation apparatus removes hydrogen gas from biogas produced in the methane-fermentation process. The aeration device guides the biogas after the removal of hydrogen gas in the acid formation tank and performs aeration.    USE - For waste water containing highly concentrated organic component.    ADVANTAGE - The methane-fermentation processing apparatus removes inhibition factors, such as ammonia, hydrogen sulfite and hydrogen efficiently. Methane-fermentation is accelerated.    DETAILED DESCRIPTION - The methane-fermentation processing apparatus comprises an acid formation tank (1), a methane-fermentation tank (3), a separation apparatus and an aeration device. The acid formation tank decomposes waste water containing organic components into a lower fatty acid with an acid formation microbe. The methane-fermentation tank ferments and processes the lower fatty acid in the process liquid ejected from the acid formation tank by a methanogen. The separation apparatus removes hydrogen gas from biogas produced in the methane-fermentation process. The aeration device guides the biogas after the removal of hydrogen gas in the acid formation tank and performs aeration. An INDEPENDENT CLAIM is included for a methane-fermentation processing method. Waste water containing an organic component is introduced into the acid formation tank and is decomposed into lower fatty acid with the acid formation microbe. The lower fatty acid in the process liquid ejected from the acid formation tank is fermented by a methanogen. Hydrogen gas is removed from the biogas and the biogas is aerated.    DESCRIPTION OF DRAWING(S) - The figure shows a flow chart of the methane-fermentation processing apparatus.    Acid formation tank (1)    Filtration device (2)    Methane-fermentation tank (3)    Alkali chemical addition device (4)