Abstract: A method for operating a fermentation plant with at least one digester (1) that is supplied with a substrate (1a). The substrate (1a) is percolated using a percolate (2a) from a percolate container (2) and biogas that is generated via the percolation process in the digester (1) or/and in the percolate container (2) is drawn off. The drawn off biogas is treated in a biogas treatment device (3) and the CO2-containing exhaust gas that is generated during the treatment is introduced into the digester (1) using a purge line (4), for forcing out and drawing off the biogas that was generated in the digester (1). Alternatively CO2-containing biogas that was generated in an additional digester (1) in a different fermentation process can be introduced into the digester (1) using a purge line (4) for forcing out and drawing off the biogas that was generated in the digester (1).

Abstract: A method for operating a fermentation plant with at least one digester that is supplied with a substrate. The substrate is percolated using a percolate from a percolate container and biogas that is generated via the percolation process in the digester or/and in the percolate container is drawn off. The drawn off biogas is treated in a biogas treatment device and the CO2-containing exhaust gas that is generated during the treatment is introduced into the digester using a purge line, for forcing out and drawing off the biogas that was generated in the digester. Alternatively CO2-containing biogas that was generated in an additional digester in a different fermentation process can be introduced into the digester for forcing out and drawing off the biogas that was generated in the digester. The CO2-containing purge gas is forced to pass through the substrate dislodging any trapped biogas.