The screw extruder has a casing (2-6) formed from several casing members (1) and in it are mounted screws (14) formed from screw members (10, 11). Between the casing members (3-6) are arranged orifice plates (19), which block the passage of the screws (10) with the exception of a restricted gap. A gear (26) is provided for driving the screw (10, 11). The screw shafts (12, 13) extend through the gear (26) and are supported on a thrust bearing, fixed by means of tie rods (25) to the casing (1). As a result of this construction, the screw press can be used for processing widely differing materials, without any significant modifications. Any liquid is removed by suction and the resulting solids are dried and can be briquetted by a shaping head.