[PROBLEMS] To improve separation efficiency of litter from organic waste containing litter and feces, to improve litter crushing efficiency, to increase the amount of biogas produced by methane fermentation, and to further improve methane fermentation To provide a methane fermentation method and a methane fermentation system capable of increasing the utility value of later digestive juice and reducing the amount of waste. SOLUTION: A first litter separating step 2 for separating a litter from organic waste containing litter and feces, a crushing step 3 for crushing the litter separated in the first litter separating step 2, and a first litter separation. Digestion generated in methane fermentation process 5 and methane fermentation process 5 in which the organic waste after separation of the litter in process 2 and the litter crushed in crushing process 3 are introduced into a methane fermentation tank and methane fermented A second litter separating process 6 for separating the litter from the liquid, and the digested liquid after the litter is separated in the second litter separating process 6 is used as an organic waste for the first litter separating process 2 Methane fermentation method and methane fermentation system to be added. [Selection] Figure 1【課題】敷料と糞とを含む有機性廃棄物からの敷料の分離効率を向上でき、敷料の破砕効率を向上できると共に、メタン発酵で生成するバイオガスのガス量を増加でき、更に、メタン発酵後の消化液の利用価値を高め、廃棄量を削減できるメタン発酵方法及びメタン発酵システムを提供すること。【解決手段】敷料と糞とを含む有機性廃棄物から敷料を分離する第１敷料分離工程2と、第１敷料分離工程2で分離された敷料を破砕する破砕工程3と、第１敷料分離工程2で敷料が分離された後の有機性廃棄物と、破砕工程3で破砕された敷料とをメタン発酵槽に導入してメタン発酵するメタン発酵工程5と、メタン発酵工程5で生成した消化液から敷料を分離する第２敷料分離工程6と、を有し、第２敷料分離工程6で敷料が分離された後の消化液を、第１敷料分離工程2に供される有機性廃棄物に添加するメタン発酵方法及びメタン発酵システム。【選択図】図１
