NOVELTY - The apparatus has a digester (1) that stores the sludge. A sewage-gas transport mechanism (8) recovers the sewage gases emitted from the sludge of the digester, and returns the recovered sewage gas in the digester. A gas dispersion apparatus (16) is connected to the sewage-gas transport mechanism, and provided to distribute the sewage gas as foam in the digester. A stirring blade (4) is set to stir the sludge containing foam of sewage gas, and positioned upwards rather than the gas dispersion apparatus. The gas dispersion apparatus is positioned at the bottom portion of the digester.    USE - Apparatus for processing methane fermentation treatment of sewage sludge such as livestock excrement, excrement sludge, purification-tank sludge, life system, or business organic refuse.    ADVANTAGE - The viscosity of the sludge in the digester is dropped by injection of sewage gas to the sludge. Therefore, the sludge in the digester is stirred forcefully and deposition prevention of the sludge to crushing of a scum or the wall surface of digester bottom portion is achieved. As a result, reduction of stirring power and generation of sewage gas is maintained favorably. The sludge in the digester is stirred forcefully, regardless of the shape of the digester.    DETAILED DESCRIPTION - A draft tube is provided in the digester. The sewage-gas transport mechanism is set to recover the sewage gases emitted from the sludge of digester, set to induce the recovered sewage gas in a draft tube, and set to form the bubble of the sewage gas in draft tube. The stirring blade is positioned in the draft tube. The stirring blade is provided to rotate the upward flow or downward flow of sludge containing foam of sewage gas in the direction formed in the draft tube. The stirring blade is positioned upwards rather than the gas outlet of sewage-gas transport mechanism. The stirring blade is positioned below rather than the gas outlet of sewage-gas transport mechanism. A sludge supply tube (3) is provided to supply the sludge in the digester.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the methane fermentation processing apparatus. (Drawing includes non-English language text)    Digester (1)    Sludge supply tube (3)    Stirring blade (4)    Sewage-gas transport mechanism (8)    Gas dispersion apparatus (16)