NOVELTY - The device comprises a supply unit (2) provided with container for floated lignocellulosic substrates that are supplied to a lower portion of the container, a transport unit (3) for the substrate, and coupled crusher (4) or squeezer provided on the transport unit. The squeezer includes a dewatering device for the substrate. The dewatering device is coupled to the container so that the container is recirculated to supply. The container comprises a mechanical conveyor for air, an ultrasound generating device, an agitator, a rabble rake, and/or a heating device for a fluid with the substrate.    USE - The device is useful for digestion of lignocellulosic substrates for a plant for biogas production (claimed).    ADVANTAGE - The self cleaning device allows complete digestion of lignocellulosic substrates in an easy and energy efficient manner.    DETAILED DESCRIPTION - The device comprises a supply unit (2) provided with container for floated lignocellulosic substrates that are supplied to a lower portion of the container, a transport unit (3) for the substrate, and coupled crusher (4) or squeezer provided on the transport unit. The squeezer includes a dewatering device for the substrate. The dewatering device is coupled to the container so that the container is recirculated to supply. The container comprises a mechanical conveyor for air, an ultrasound generating device, an agitator, a rabble rake, a heating device for a fluid with the substrate in the container, and/or a heating device for recirculating a material to a feed line and/or the container. The supply unit includes a screw conveyor that is provided at the lower portion of the container and at a bottom of the substrate. A supply direction is changed by rotating direction of a screw, and the impurities are transported from the container. The screw conveyor is located inside or outside of the container. The crusher is a bio-extruder such as a double-screw disc extruder, a mill, or a hammer mill. A housing includes a cover surrounding mutually spaced discs. The supply unit is arranged before the crusher so that the substrate to be digested is supplied from the supply unit. The container is connected via a transport unit to the supply unit, so that the substrate is supplied via the supply unit to the crusher. The device further comprises a supply unit for enzymes for grinding and dehydrating the substrate provided after the crusher. The crusher includes a fermenter (6), or another crusher includes a fermenter for grinding and dehydrating the substrate as part of a plant for biogas production. The fermenter is coupled with the container so that a certain amount of fermented and enzyme-containing substance is recirculated to the container. A stopper is provided between the crusher and the fermenter as a part of a plant for biogas production.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a device for digestion of lignocellulosic substrates.    Supply unit (2)    Transport unit (3)    Crusher (4)    Connecting line (5)    Fermenter. (6)