Abstract: A container (1) for the fermentative production of biogas from organic substrates, which container comprises an axial stirrer (9), one or several inlet devices (2) for filling the container (1), one or several outlet devices (3, 4) for emptying the container (1) and withdrawing a fermentation residue, an external conduit (5) for supplying a fermentation mixture into a closed circular pipeline (7) with several outlets (8) for spraying on the surface (14) of the fermentation mixture, with the sprayed fermentation mixture optionally coming from the lower half of the container (1), a device (11) for withdrawing the biogas produced and an apparatus (10) for controlling the temperature of the fermentation mixture; a process for the fermentative production of biogas from an organic substrate, a process for suppressing foam formation during the fermentative production of biogas, and a process for the improved conversion of oils and fats in organic substrates during the fermentative production of biogas, which can be