| 摘要 |
PROBLEM TO BE SOLVED: To stably keep fermentation efficiency by preventing the flow-out of methanogen (SS) to the outside of a tank caused by accompanying the pulling out of fermentation sludge by membrane separation and keeping the concentra tion of SS in a methane fermentor in high concentration at a low cost. SOLUTION: High concentration organic waste is introduced into the fermentor 1 to cause methane fermentation, the fermentation sludge is circulated between the fermentor 1 and a membrane separation tank 2 and is solid-liquid separated by a membrane separation device 3 of the membrane separation tank 2 and the membrane permeated liquid is taken out outside of the system. As a result, the SS concentration in the fermentor is kept to equal to or more than an effective value necessary for keeping the methane fermentation, a gas in the fermentor 1 is aerated by a gas diffusing device 3b arranged under the membrane separation device 3, a gas liquid mixed phase flow produced by the aerated gas is acted as scavenging flow with respect to the membrane surface of the filtration membrane of the membrane separation device 3 and the excess fermentation sludge is taken out from the bottom of the fementor 1.
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