NOVELTY - The apparatus (11) has membrane separation unit (13) that concentrates digested sludge in membrane fermentation tank (12). A membrane transport liquid derivation piping (30) passing into solubilization tank (15), derives the membrane transport liquid permeating separation membrane (19) of membrane separation unit, to exterior. A heat exchange unit heat-exchanges between membrane transport liquid and fluid organic substance in solubilization tank to solubilize organic substance in liquid state or slurry state, through heat medium and heats membrane transport liquid.    USE - Methane fermentation treatment apparatus for treating hot organic substance such as distilled alcoholic liquor, distilled waste liquid obtained from alcohol manufacturing process, foodstuff waste and industrial waste.    ADVANTAGE - The pH value for methane fermentation can be maintained appropriately. The precipitation of magnesium phosphate ammonium (MAP) in membrane transport liquid derivation piping can be suppressed. The cost of the treatment apparatus can be reduced.    DETAILED DESCRIPTION - The material transport liquid passes through organic substance storage tank (33) of material supply unit (14). The material supply unit has material supply piping (16) for supplying organic substance to methane fermentation tank, which contacts the membrane transport liquid derivation piping. The solubilized organic substance is liquefied at high temperature than the digested sludge. An INDEPENDENT CLAIM is included for methane fermentation treatment method.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the methane fermentation treatment apparatus. (Drawing includes non-English language text)    Methane fermentation treatment apparatus (11)    Membrane fermentation tank (12)    Membrane separation unit (13)    Material supply unit (14)    Solubilization tank (15)    Material supply piping (16)    Separation membrane (19)    Membrane transport liquid derivation piping (30)    Storage tank (33)