Wastewater pump comprising a reversible motor (110) driving a rotor (160) equipped with blades (170).The rotor (160) is a disc (165) bearing pivoting blades (170) each mounted on a radial spindle (167) borne by the rotor. Each blade (170) is composed of a plate (171) bearing an articulation node (175) engaged on the spindle and a cutter (172) on the back of the plate forming a prop supporting the plate in the active position when the rotor (160) is rotating in the forward direction (D), and the cutter (172) projecting in the peripheral direction when the rotor (160) turns in the reverse direction (R), the plate (171) being applied against the disc (165). A fixed ring surrounds the disc and bears at least one cutter (135).