The present invention provides an integrated multiphase biocatalytic reactor and separator system (1), comprising, an upflow reaction section (2), a separation section (3), and a recycle flow section (4), wherein: the upflow reaction section (2) comprises a gas phase inlet (12), arranged to introduce a gas phase (G) for lifting a reactor flow (C) comprising a first and a second phase liquid; the separation section includes a first separation zone (31) configured to degas an effluent flow from the upflow section, and a second separation zone (32), i.e. a liquid-liquid phase separator, configured to separate the degassed effluent in a lower liquid phase (LP) and an upper liquid phase (UP), said second separation zone further comprising an outlet (15) for collecting the upper liquid phase and an outlet for recirculating the lower liquid phase back to the upflow reaction section via the recycle flow section (4).

The invention relates to a plug flow fermenter (1) for a biogas plant, having a reactor container (2) designed as an elongated straight tube, in the reactor interior (9) of which a substrate to be fermented, preferably by dry fermentation, can be fermented as plug flow while producing biogas, wherein the reactor container (2) has at least one container inlet (10), via which the substrate to be fermented can be fed to the reactor interior (9), and at least one container outlet (12) spaced apart from the container inlet (10) in the flow direction (x) of the plug flow, via which the fermented substrate can be discharged from the reactor interior (9), and wherein a plurality of separately exchangeable agitating devices (19) is arranged spaced apart in the reactor interior (9) when seen in the longitudinal extension direction and thus in the flow direction of the plug flow.