NOVELTY - The percolator comprises a rotor (2) to distribute a percolate on a solid substrate. The rotor includes rotor blades (20). A shaft is located at a first end of the rotor, and is rotatably mounted at a second end in a bearing. The bearing is connected via arm with a percolate supply (60) for supplying the percolate to the rotor. The percolate supply is arranged in parallel to a rotational axis of the rotor. The blades are shaped so that a fluid of percolate flowing from the percolate supply is radially deflectable with respect to the axis of rotation. The rotator is drivable by the blade.    USE - The percolator is useful for applying a percolate on a solid substrate of a biogas plant that is useful for processing stackable biomass (claimed).    ADVANTAGE - The percolator uniformly applies the percolate on the solid substrate of the biogas plant.    DETAILED DESCRIPTION - The percolator comprises a rotor (2) to distribute a percolate on a solid substrate. The rotor includes rotor blades (20). A shaft is located at a first end of the rotor, and is rotatably mounted at a second end in a bearing. The bearing is connected via arm with a percolate supply (60) for supplying the percolate to the rotor. The percolate supply is arranged in parallel to a rotational axis of the rotor. The blades are shaped so that a fluid of percolate flowing from the percolate supply is radially deflectable with respect to the axis of rotation. The rotator is drivable by the blade. The rotor blades are arranged at the same distance to each other and arranged at an angle of 120 degrees , and have different shape, different size and/or a different pitch. One of the blade is shaped such that an angle between the oncoming percolate before the rotor and the percolate leaving from the rotor blade is less than 90 degrees C. The rotor blades are shaped so that outgoing percolate is annularly distributed by the rotor, and include a curved region (21) and a straight region (22). The curved and straight regions protrude tangentially and/or radially to the shaft. The rotor is driven by a driving device.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic perspective view of a percolator.    Rotator (2)    Rotor blade (20)    Curved region (21)    Straight region (22)    Percolate supply. (60)