Patent ID: 9504964
Filing Date: 2016-11-29
CPC Classification: B01D

Claim Text:
1. A filtration method for operating a filtration module, the module comprising: a housing with at least one filter element positioned therein, the filter element defining a first space in the housing at a feeding side of its filtering surface and a second space at an opposite permeate side thereof; a liquid feed opening out in the first space at the feeding side of the filter element; and a liquid permeate outlet in flow communication with the second space at the permeate side of the filter element; in which the filter element is placed in an upright position, the liquid permeate outlet being positioned at a lower end of the filter element, and a gas feed being provided opening out in the second space at said permeate side of the filter element, the method comprising the steps of: feeding a first stream of pressurized liquid to be filtered to the first space at the feeding side of the filter element; discharging filtered liquid permeate from the second space at the permeate side of the filter element; and feeding pressurized gas to the second space at the permeate side of the filter element; wherein a cross-flow filtration module is used having a retentate outlet in flow communication with the first space at the feeding side of the filter element, which retentate outlet is positioned at another level than the liquid feed along the filter element; wherein non-filtered retentate is discharged via the retentate outlet from the first space at the feeding side of the filter element such that a pressure drop of the liquid between the liquid feed and the retentate outlet is created to have the liquid forced to flow across the filtering element from the liquid feed towards the retentate outlet; and wherein the step of feeding pressurized gas to the second space is performed during filtration simultaneously with the steps of feeding the first stream of the pressurized liquid to be filtered to the first space and discharging the filtered liquid permeate from the second space, in which the second space fills itself with the liquid permeate in a first portion of the second space and with the pressurized gas in a second portion of the second space, wherein a separation level between the liquid in the first portion and the gas in the second portion of the second space can be adapted by adapting a gas pressure of the pressurized gas.