To provide a methane fermentation tank capable of effectively subjecting highly concentrated sludge such as dehydrated sludge or the like to methane fermentation.
In the methane fermentation tank wherein highly concentrated sludge is charged in an anaerobic tank to be subjected to methane fermentation, stirring blades are attached to the rotary shaft almost vertically suspended into the anaerobic tank and the attaching angle of the stirring blades is set so that the attaching angle of the stirring blades on the side of a sludge draw- out position is larger than that of the stirring blades on the side of a sludge charging position and, further, a screw blade is attached to the rotary shaft extended toward the sludge draw-out position in the vicinity of the draw-out side thereof.
UKAI NOBUYUKI
SHINDO YOSHITAKE
MAEDA TOMOYOSHI
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