NOVELTY - Fermentation device comprises a fermenter for fermenting organic material and providing a fermenter output material; and an intermediate tank for conditioning the fermenter output material, thus providing a conditioned material; the intermediate tank having an inlet for receiving the fermenter output material; the intermediate tank having an outlet for outputting the conditioned material; the fermentation device comprising a mixing device for mixing the content of the intermediate tank; and a dewatering device for receiving the conditioned material.    USE - The fermentation device is useful for fermenting organic material.    ADVANTAGE - A removable paddle has the advantage that the paddle geometry of the mixing device can be adjusted to the content of the fermenter and hence to the content of the intermediate tank. Removable paddle has the further advantage that it can easily be changed if the paddle gets broken or otherwise damaged. Due to the relatively small size of the intermediate tank the intermediate tank can be emptied typically in no more than one day, making a change of a paddle for maintenance or adaption purposes economically reasonable.    DETAILED DESCRIPTION - Fermentation device comprises a fermenter for fermenting organic material and providing a fermenter output material; and an intermediate tank for conditioning the fermenter output material, thus providing a conditioned material; the intermediate tank having an inlet for receiving the fermenter output material; the intermediate tank having an outlet for outputting the conditioned material; the fermentation device comprising a mixing device for mixing the content of the intermediate tank; and a dewatering device for receiving the conditioned material, the dewatering device being operable for dewatering the conditioned material. INDEPENDENT CLAIMS are:    (1) a method of operating a fermentation device comprising introducing a fermenter output material into an intermediate tank; mixing the fermenter output material in the intermediate tank, thus providing a conditioned material; and dewatering the conditioned material;    (2) control unit for a fermentation device, the control unit being configured for carrying out the method above; and    (3) computer program being adapted for, when being executed by a data processor device, controlling the method above.