PURPOSE: To superimpose the pressurizing separation and the negative pressure separation on slurry to effectively perform solid-liquid separation by installing a negative pressure suction chamber outside a slit of a drum through a filter body, connecting it to a vacuum pump and a drain passage and on the other hand, connecting a slurry pressurizing valve to a pressurizing cylinder.

CONSTITUTION: A pressurizing cylinder 11, such as a hydraulic cylinder is installed in the upper part of a drum 10. Slurry pressurizing valves 15 in the shape of a downward taper are provided on a rod 13 through plural radial arms and openings 17 made in a partition wall 16 which is laterally installed in the middle of the drum 10 are opened and closed integrally with the rod 13 moving upwards and downwards. A negative pressure suction chamber 24 is installed outside slits 20 of the drum 10 through filter bodies 21, 22, 23 and connected to a vacuum pump 28, and a clarified water storage chamber 24' in the lower part is connected to a drain passage 29. As a result, the solid- liquid separation of the supplied slurry with a push-pull double function is performed to separate the solid-liquid selectively.