Abstract: A device for implementing anaerobic fermentation having a vertically standing fermentation tank with a fermentation chamber in which organic material can be fermented, a feed device to mix fresh organic material with inoculant and to carry it through to an inlet in the fermentation tank, which is also provided with a cone with an extraction outlet via which fermented material can be discharged and an outlet for biogas, where the device is also provided with two or more return openings via which a fraction of the partly fermented material, located between the inlet and the outlet, is removed from the fermentation tank and is carried up through feed lines between the mixing pump and the inlet that are situated partly and vertically in the fermentation tank.

Abstract: Method for the anaerobic fermentation of organic material, whereby the organic material to be fermented is put in a fermentation tank (1) together with an inoculant and moves or is moved from an inlet (6) of the fermentation tank (1) to an outlet (9) thereof, whereby the fermented material is removed from the tank (1) via the outlet (9), wherein a fraction of the fermenting material which is situated between the inlet (6) and the outlet (9) is removed from the fermentation tank (1) via a return opening (12) and is used as an inoculant, while the fermenting material between the return opening (12) and the outlet (9) is still after-fermented for a certain while before it is removed from the fermentation tank (1) via the outlet (9).