PROBLEM TO BE SOLVED: To provide a highly efficient organic waste recycling system which is environmentally friendly without using a fossil fuel as an energy source for generating saturated vapor necessary for hydrolysis of organic wastes.SOLUTION: Prior to treatment of the organic waste by the hydrolyzing devices 4 and 5, a polymeric compound is degraded to a low-molecular weight material, is adjusted to be pH 7.5 by adding an alkaline agent and is solubilized. Then, the solubilized material is efficiently fermented in a methane fermentation tank 14. A high-temperature, high-pressure saturated vapor is generated by a boiler 17 using the produced methane gas as a raw material to be used for hydrolyzing treatment. Since the tightly-sealed air in a hydrolyzing device area is fed to a boiler, offensive odor is cleaned away by combustion in the boiler, is controlled to the utmost extent in facilities and does not leak outside. Besides, a deodorizing treatment liquid or the like is fed to a methane fermentation-adjusting tank 13, and the residue after methane fermentation becomes a liquid or solid fertilizer. Thus, there is provided a highly efficient organic waste-recycling system of environmentally friendly zero emission.
