SCHNECKENPRESSE

In a screw press, an outer tube (5), over which a screen (4) is tensioned, is divided into a freely rotatable condensing zone at the front half thereof, and a filtering and dewatering zone at the rear half thereof, a freely rotatable screw shaft (7) is provided within the thus-divided outer tube (5a, 5b), filtered fluid is separated from sludge supplied to the starting end of the condensing zone by the screen (4) of the outer tube (5a), and a cake is removed at a discharge port (29) at the rear end of the outer tube (5b) of the filtering and dewatering zone. A sludge supply path (28) is provided in the screw shaft (7), a supply hole (28a) of this supply path (28) is formed at the starting end of the outer tube (5a) of the condensing zone, and a scraper (33) extends on the outer periphery of a screw vane (6) from the starting end to the ending end. The scraper (33) is caused to make pressured sliding contact with the inner peripheral surface of the outer tube (5a), so that filtering and dewatering are performed as the outer tube (5a) of the condensing zone and the screw shaft (7) are rotated.