SCREW PRESS WITH FILTER PLATES

A screw press (14) for separating liquid from a solid-liquid mixture, comprises a casing (18) having inlet and outlet sections (24, 26), and a filter section (28) therebetween. The filter section (28) includes an axially extending stack of coplanar filtration plates (36) defining a core passage for receiving a screw configured to convey the solid-liquid mixture from the inlet section (24) to the outlet section (26) while compressing and dewatering the solid-liquid mixture by forcing at least part of the liquid content of the mixture to be expelled out of the casing through inter-plate gaps (40) defined between each pair of adjacent filtration plates (36). The filtration plates (36) are fixed relative to one another and clamped in direct intimate face-to-face contact by a clamping assembly (38) operable for applying a predetermined axially clamping pressure substantially uniformly about the core passage. The inter-plate gaps (40) are controlled by the surface roughness (R) of the plates (36) and the clamping pressure.