Abstract: A fermentation device for biological degradation of substrate containing organic material and for recovery of biogas produced by degradation has an elongate closed container having a first end and a second end opposite the first end. The first end has an inlet opening for untreated substrate and the second end has at least one removal opening for treated substrate. The container has at least one removal opening for biogas. The container has several reaction cells provided with individually driven mixing units. The mixing units have mixing unit shafts positioned transversely to a longitudinal extension of the container and mixing impellers mounted on the mixing unit shafts and driven on a circular path. The mixing unit shafts are arranged at axial spacings smaller than a diameter of the mixing units so that the mixing impellers when the mixing unit shafts rotate pass trough an overlap range.

Abstract: Special guide means 7 are located in the interior of a loop reactor for circulating the reactor contents. The guide means 7 has at least one central gas supply means 1 with gas distribution means 2 attached thereto for gas charging into the guide means 7. These loop reactors are used, e.g., as biogas reactors for treatment of biowastes or renewable raw materials. The gas distribution means 2 as gas guide elements are open to the bottom and are located above the gas exit openings 3 of the central gas supply means 1.