PURPOSE: To use an inexpensive equal volume screw and provide the sufficient dehydration effect by disposing a hydration plug rotating solid contents synchro nously and compressing a material to be carried on the upper section of the screw and feeding the same to a drain pipe while solid-liquid separation is carried out in a device for carrying out the solid-liquid separation by the screw and sending out the solid contents.

CONSTITUTION: Garbage discharged from a cleaning tray and crushed is passed through a feeding-in pipe 24 together with service water and introduced into an annular space 11c of a filter section 1. The garbage and service water are moved upward by a ribbon screw 19 rotated by a motor 18. At that time, the water content is fed from a filter inner cylinder 11a and passed through a drain pipe 12, and also passed through a filter outer cylinder 11b and a drain pipe 25 and drained out. On the other hand, as the volume formed by the action of a dehydration plug 20 installed on the upper section of the screw 19, namely the volume formed by the plug 20 and the filter outer cylinder 11b, is smaller than the carrying volume of the screw 19, the garbage is reduced in its volume and dehydrated. Then, a material to be carried is transferred to the drain pipe 21 by a blade 20a set on the dehydration plug 20.