Apparatus for the production of biogas by anaerobic fermentation of biomass

The apparatus is used to produce biogas by bacterial anaerobic fermentations from biomass, that is to say from animal waste, in particular from farm slurry, or from comminuted and suspended vegetable material. Used for this purpose is a fermenter part (1) which receives the biomass and has a vertically displaceable gas bell (2). The pressure/volume energy of the lifting motion caused by alternate filling up with and removal of biogas is utilised in order, by means of gas conduction fittings (3) in the bell (2), to break up and remove the floating layer in the fermenter part (1), consisting of the undecomposed portion of biomass. This energy is also used to feed in fresh slurry or fresh biomass and to ensure thorough mixing of the biomass by means of the perforated plates (6). The apparatus according to the invention makes it possible to produce biogas without external energy input.