摘要 |
<p>Cross-flow filter (8) comprising a highly flexible filter support (21) (thickness not greater than 1 mm) having a spiral of, or spaced, parallel lengths, of, double-ply material whose plies are seamed together along spaced, longitudinal seams to provide an array of side-by-side tubes. During filtration (when the filter support (21) is under the pressure of the feed) the tube walls bulge out and the filter zone is restrained solely by tensile forces in the filter support (21) itself. Substantial movement of the filter support (21) is possible in the direction at right angles to its face when the pressures on either side of the filter support are equal. One application is when the filter (8) is connected downstream of an aeration vessel (11) with no intervening vessel, the concentrate outlet (2) of the filter (8) being connected to the aeration vessel (11) for sludge return. This enables the size of the aeration vessel (11) to be substantially reduced.</p> |