Abstract

A drum (or disc) having a filtering membrane formed on the surface thereof is rotated continually into and out of a bath containing particulate material to be filtered and de-watered, such that a filter cake is formed on the outside of the membrane. A vacuum is provided at the center of the drum or disc structure to suck moisture from the filter cake during the portion of the cycle when this filter cake is out of the bath (the drum or disc being rotated at a very slow speed). A vibrator member having a surface in the form of a long narrow strip is placed against the drum or disc across a limited longitudinal slice thereof in a region of the filter cake, such that the sucking pressure has a substantial non-vibrating region to work on each side of the vibrated strip. The vibrational energy delivers vibration to the filter cake in such a manner as to upset the capillary equilibrium and thus facilitate the separation of the liquid from the filter cake. The vibratory member may be in the form of a resonantly vibrated elongated bar or tube which is biased against the outer wall of the drum or disc.