A filtration device designed for the purpose of recovering filtrate from wastewaters is characterized by a rotor system (2) that is drivable in rotary manner about a horizontal axis (5) in a liquid bath in a receptacle (1), and which serves as the support for multiple assemblies (17) of filter discs, the interior spaces of which are connected to the suction side of a pump (39) via a collection chamber (29). The liquid to be filtered is transported with the aid of a pump (40) that is connected to a plurality of distributor lances (35) that extend parallel to and close to the hollow shaft (21) that supports the rotor system (2) via a line (31) with the interposition of a prefilter (41) that is intended to separate a coarse fraction. The central introduction of the prefiltered liquid distributed evenly over the length of the rotor system (2) via the distributor lances (35) in conjunction with a network (36) of lines designed to introduce air bubbles into the liquid bath and located in the bottom of the receptacle (1) results in a stable operation that also suppresses the formation of deposits and engenders high and consistent filter efficiency.