Abstract: A stationary chamber having a perforated peripheral wall contains an axial rotor having rubber-like radial carrier blades which, as the rotor rotates, are indented at their outer edges by guide means having helical turns extending along said peripheral wall. A passage allows ambient gas to enter the chamber so that the rotor's action on a liquid-solids mixture entering a first part of the chamber maintains a free liquid surface therein. The carrier blades and rotor coact with the helical turns to carry a liquid-bearing cake of the solids through the free liquid surface and thence through a second part of the chamber to a solids outlet, during draining of liquid from the cake through the perforated peripheral wall.