| 摘要 |
PROBLEM TO BE SOLVED: To shorten a waiting time until the resumption of acid fermentation by preventing a fall in the methane fermentation function of a reaction tank due to methane bacteria precipitating or sticking to the internal wall of the tank when the supply stop period of a stock solution to an acid fermentation tank is a predetermined period or longer.SOLUTION: A methane fermentation apparatus 1 includes an acid fermentation tank 2, a condition tank 3, a reaction tank 4 and a treated water tank 5, and is configured to supply an alkaline pH adjuster to the acid fermentation tank 2 and the condition tank 3 according to the pH of the respective tanks and to return treated water in the treated water tank 5 to the acid fermentation tank 2 and the condition tank 3. The methane fermentation apparatus 1 includes a control device 30 stopping the return of treated water to the acid fermentation tank 2 from the treated water tank 5 while maintaining the return of treated water to the condition tank 3 from the treated water tank 5 when the supply of a stock solution to the acid fermentation tank 2 is stopped. |
