Screw filter press for sludge dewatering treatment The sludge dewatering screw press machine for wastewater treatment developed by holly utilizes the dewatering principles of force-water homo-direction, thin-layer dewatering, proper pressure and extension of the sludge dewatering path. The new equipment, more advanced than the traditional dewatering equipment which are easily blocked, unsuitable for low-concentrated sludge and oily sludge, of high consumption and difficult to operate, well eliminate these problems and are of higher efficiency and power saving .