NOVELTY - The plant for the production of biogas through fermentation, comprises a fermentation reactor (18) in which fermentable substances are fermented through bacteria under formation of biogas, first and second thickening devices (20, 22) and/or floatation unit (26), a mixing container (14) for mixing the fermentable raw materials with water and/or a hydrolysis vessel. The first thickening device is a rotatable plate filter or a centrifuge and the second thickening plate is a screw press, a centrifuge or a screen belt press.    USE - Plant for the production of biogas through fermentation.    ADVANTAGE - The plant ensures efficient and reliable production of biogas with high yield and low investment and operating cost in less time-consuming manner.    DETAILED DESCRIPTION - The plant for the production of biogas through fermentation, comprises a fermentation reactor (18) in which fermentable substances are fermented through bacteria under formation of biogas, first and second thickening devices (20, 22) and/or floatation unit (26), a mixing container (14) for mixing the fermentable raw materials with water and/or a hydrolysis vessel. The first thickening device is a rotatable plate filter or a centrifuge and the second thickening plate is a screw press, a centrifuge or a screen belt press. The floatation unit is a pressure release floatation unit with a pressure release floatation reactor. The pressure release floatation unit has a supply line for a pH-adjusting unit, a supply line for precipitating agent and/or a flocculation agent, a supply line for compressed gas, and a gas separation equipment, which is connected with the pressure release floatation unit over a pipeline and in which the compressed gas supply line ends. The fermentation reactor comprises a supply line for supplying a suspension or solution containing fermentable substances, a gas removal line for biogas, and a removal line for the fermented suspension or mixture. The removal line for the fermented suspension is connected with the first thickening device, which has a first removal line for a first filtrate and a second removal line for thickened suspension. The second removal line for the thickened suspension of the first thickening device is connected with the second thickening device, which has a first removal line for a second filtrate and a second removal line for the thickened suspension. The first removal line for the first filtrate of the first thickening device is connected with the floatation unit. The mixing container is arranged upstream to the fermentation reactor. The floatation unit has a first removal line for solid material and a second removal line for third filtrate. The removal line for the third filtrate is connected directly or indirectly with the mixing container. The removal line for the fermented mixture is connected with the floatation unit. The first removal line for the suspension is connected with the first thickening device, which has a first removal line for a second filtrate and a second removal line for thickened suspension. The second removal line for the thickened suspension of the first thickening device is connected with the second thickening device, which has a first removal direction for a third filtrate and a second removal line for the thickened suspension. The first removal line for the second filtrate guides from the first thickening device to the removal line for the fermented mixture of the fermentation reactor. The first removal line for the third filtrate of the second thickening device guides in the removal line for the fermented mixture of the fermentation reactor. The hydrolysis vessel is arranged downstream to the mixing container and upstream to the fermentation reactor. An INDEPENDENT CLAIM is included for a method for the production of biogas through fermentation.    DESCRIPTION OF DRAWING(S) - The figure shows a plant for the production of biogas through fermentation.    Mixing container (14)    Fermentation reactor (18)    First thickening device (20)    Second thickening device (22)    Floatation unit. (26)