Centrifugal pump with an integrated cutting

The invention relates to a centrifugal pump assembly with a cutting unit (1) which is arranged before the flow of the medium in an impeller (2). The cutting unit (1) has a cutting surface (3) with openings (5) through which the medium flows. A rotating cutting body (4) abuts against the cutting face (3). The cutter body (4) and the impeller (2) are displaced jointly by a motor (11) in rotation. According to the invention a control device is associated with the motor (11), which the impeller (2) and the cutting body (4) can be intermittently rotate in different rotational direction. The impeller (2) has blades (16) which extend in a purely radial direction. Thereby, the centrifugal pump in both directions of rotation in the same characteristic.