Abstract: A method and system for use with rotary vacuum filters having a plurality of circumferentially spaced filter segments, for selectively applying blower air to the filter segments at predetermined rotational positions at which relatively unrestricted openings to the valve ports are provided to thereby blow the filter segments, and for bypassing the stream of blower air to the atmosphere when the filter segments are not blown. The apparatus for practicing the invention may also include a blow-back trap for trapping excessive amounts of residual blow-back filtrate during blowing of the filter segments.

Abstract: In mechanical filters, structure is provided for mounting a string-like member in closely spaced relation to its moving filter medium. At least one pick mounted on a rotating shaft is provided for periodically plucking the string-like member so that the string-like member vibrates against the filter medium. A rod mounted perpendicular to the path of movement of the filter medium past the string-like member acts as a guide to prevent the pick from catching the string-like member and controls the vibration of the string-like member in a plane substantially perpendicular to the path of movement of the filter medium thereby to obtain the most effect of the impact. The vibration or slapping of the string-like member against the filter medium causes filter cake formed thereon to be detached therefrom or to be compacted. In a belt-type of drum filter, the string-like member is preferably located between the breaker and discharge rolls.