| 摘要 |
A method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall comprises the steps of: (a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; (b) periodically reducing the transmembrane pressure to about zero for periods not in excess of about 2 minutes thereby periodically permitting enhanced erosion of the sludge layer so as to reduce its thickness; and (c) re-establishing the transmembrane pressure after each intermittent reduction, whereby the time-averaged filtration flux is increased. Typically, the transmembrane pressure is established by creating a net positive pressure within the filter tube, and the periodic reduction of the transmembrane pressure is achieved by periodically reducing the net positive pressure to about zero. Also disclosed is a method of increasing the cross-flow filtration flux of a suspended solids laden liquid through a porous filter tube wall, comprising the steps of: (a) flowing the liquid through the filter tube and permeating the liquid through the tube wall by establishing a transmembrane pressure within the tube, thereby depositing at least a portion of the solids on the inner surface of the tube as a sludge layer; (b) periodically increasing the circulation velocity of the liquid flowing lengthwise through the filter tube to a value in excess of about 7 fps, preferably between about 10 and about 20 fps, and more preferably to about 15 fps thereby permitting enhanced erosion of the sludge layer so as to reduce its thickness; and (c) reducing the circulation velocity after each intermittent increase, whereby the time averaged filtration flux is increased. Apparatus is also disclosed for practicing the methods of the invention. |
