NOVELTY - Biogas plant-fermenter container (1) comprises a service device comprising a cover side service opening (8), which is closable in a gas tight manner by means of a covering device (27). A submersible device (23), preferably a submersible stirrer or a submersible pump, which is led vertically adjustable on a guide pole (17), is removed from the fermenter container in a gas tight manner for maintenance and service operations, and is movable back into the fermentation container. A sealing element is arranged around the service opening.    USE - Used as a biogas plant-fermenter container.    DETAILED DESCRIPTION - Biogas plant-fermenter container (1) comprises a service device comprising a cover side service opening (8), which is closable in a gas tight manner by means of a covering device (27). A submersible device (23), preferably a submersible stirrer or a submersible pump, which is led vertically adjustable on a guide pole (17), is removed from the fermenter container in a gas tight manner for maintenance and service operations, and is movable back into the fermentation container. A shaft like sealing element projecting downwardly into the fermenter container-interior in the sealing position is arranged around the service opening. The absorbed and to be fermented liquid substrate is immersed in the fermenter container at least during maintenance and service operations. The gas phase region annularly enclosed by the sealing element and present below the openable service opening and above the substrate is separated in a gas tight manner from the remaining gas phase region of the fermenter container-interior. The sealing element is formed by a rigid, non-movable and inflexible and tubular stub-like collar projecting from the service opening continuously in the direction of the fermenter container-interior space. INDEPENDENT CLAIMS are also included for:    (1) carrying out maintenance and service operation at the submersible device of the biogas plant-fermenter container, comprising removing the submersible device, preferably submersible stirrer or submersible pump, which is guided in a height adjustable manner on a guide mast for maintenance and service operations, from the fermenter container, and moving back into the fermenter container, where (a) the service device further comprises a filling level measuring device, by means which the filling level of the substrate in the fermenter container is detected at least during the maintenance and service operations, and a corresponding filling level measurement signal is generated as height-actual value signal, and (b) a control device is provided, which is supplied with the filling level measuring signal. At least a conveying and/or pumping device is actuated at a detected low filling level, in which the collar is not immersed in the substrate, such that the filling level of the substrate in the fermenter container is raised to a level, at which the collar is immersed in the substrate; and    (2) a pedestal plate for use in the biogas plant-fermenter container, where the service opening is a component of the pedestal plate, from which a collar annularly enclosing the service opening protrudes downwardly in the mounted state of the pedestal plate so the collar protrudes in the fermenter container interior.    DESCRIPTION OF DRAWING(S) - The figures 1, 1a and 1b show a schematic representation of the biogas plant-fermentation container.    Biogas plant-fermenter container (1)    Service opening (8)    Guide pole (17)    Submersible device (23)    Covering device (27)