NOVELTY - The plant for the production of biogas, comprises a fermenter (2) into which a nutrient medium is introduced via an inlet opening (3) and is fermented to produce biogas, a mixer (10), which is mounted upstream of the fermenter and in which a gaseous medium (G) is miscible, heat exchanger (16) through which process heat required for the fermentation is introduced to the nutrient medium (M), and cleaning unit through which the filling quantity of the nutrient medium present in the fermenter is regulatable. The mixture of the nutrient medium and the gaseous medium is supplied to the fermenter.    USE - Plant for the production of biogas.    ADVANTAGE - The biogas plant is simple and ensures production of biogas with less operating and maintenance costs in easy manner.    DETAILED DESCRIPTION - The plant for the production of biogas, comprises a fermenter (2) into which a nutrient medium is introduced via an inlet opening (3) and is fermented to produce biogas, a mixer (10), which is mounted upstream of the fermenter and in which a gaseous medium (G) is miscible, a heat exchanger (16) through which process heat required for the fermentation is introduced to the nutrient medium (M), and a cleaning unit through which the filling quantity of the nutrient medium present in the fermenter is regulatable. The mixture of the nutrient medium and the gaseous medium is supplied to the fermenter and has a low specific weight due to the gas admixed in the mixer. The gaseous medium thoroughly mixes the nutrient medium. The mixer has a first inlet over which the nutrient medium is introduced into the mixer, a second inlet over which the gaseous medium is introduced into the mixer, and a third inlet over which the nutrient medium taken from the fermenter is introduced to the mixer. The biogas plant has a gas pipeline through which the biogas obtained from a gas storage area of the fermenter is introduced to the second inlet of the mixer. A gas compressor and/or a gas pump (13) is connected upstream to the second inlet of the mixer. The fermenter has exit points for entirely or partially fermented nutrient medium present in the fermenter. The cleaning of the filling quantity is carried out through a regulation of supply and/or removal of the nutrient medium depending on the pressure of the biogas produced in the fermenter. An INDEPENDENT CLAIM is included for a procedure for fermentation of nutrient medium in a fermenter.    DESCRIPTION OF DRAWING(S) - The figure shows a biogas plant.    Fermenter (2)    Inlet opening (3)    Mixer (10)    Gas pump (13)    Heat exchanger. (16)