The Screw Press Filter consists of a rotating screw in a slotted or perforated casing. The solids must be coarse enough so that they do not pass through the casing.
The design tends to be specific for one product so they are not usually suitable for multiple products. The pressure is usually increase along the length by reducing the screw pitch, by increasing the shaft diameter or by reducing the diameter of the casing.
Pressure is controlled by varying the size of the outlet. The shalt may be hollow for steam injection. Wash liquid can be added along the screw to achieve some washing.