A sludge screw pump is a thick slurry pump. Its main working components are an eccentric helical screw (i.e., rotor) and a screw bushing (i.e., stator) with a double-helical inner surface.A sludge screw pump is a specific application of a single screw pump for sludge and wastewater treatment. This pump utilizes an eccentric single-helix screw rotating within a double-helix bushing, pushing sludge and wastewater along the spiral grooves from the suction port to the discharge port. This is the operating principle of a sludge screw pump.