METHOD FOR RECOVERING AND RETURNING METHANE FERMENTATION ACCELERATOR

PURPOSE:To maintain high fermentation performance by recovering a powdery fermentation accelerator from a fermenting liq. discharged from a methane fermenter, and returning the accelerator into the methane fermenter to maintain the concn. of the fermentation accelerator in the fermenting liq. in the methane fermenter. CONSTITUTION:A powdery fermentation accelerator having a dissociated radical on the surface is added into a methane fermenting liq. in a methane fermenter 5. The methane fermenting liq. after the completion of fermentation is introduced into a biological aeration vessel 6, and the fermenting liq. after biological aeration is introduced into a settling vessel 7. The fermentation accelerator, settled and separated in the settling vessel 7, is taken out, and returned into the fermenting liq. in the methane fermenter 5. Namely, the fermentation accelerator, added into the fermenting liq., can be efficiently recovered and returned, the concn. of the fermentation accelerator in the fermenting liq. is maintained, and high fermentation capacity can be kept.