The MDQ / MDC-series is an organic sludge dehydrator in which the feature of multi-disc dehydrator is added on the principle of the screw press dehydrator. The cylinder screen, that incorporates the screw shaft, is comprised of a large number of fixed discs and movable discs that are placed alternately. Since only the movable discs move by contacting the outer periphery of the rotating screw, it has made the dehydrator immune to clogging.