Patent ID: 6193890
Filing Date: 2001-02-27
Classification: B01D,C02F

Abstract:
In a method for maintaining production of permeate at equilibrium flux, in a skein submerged in a solids-containing substrate held in a tank, continuously, by scrubbing hollow fiber membranes (""fibers"") of said skein with bubbles generated from scrubbing gas flowed into an aerator's air plenum at a pressure greater than the liquid head between the surface of substrate in the tank and the surface of the substrate in the plenum so as to maintain a substantially uniform flow of a stream of said bubbles through each of plural air orifices in lateral walls of said aerator, in which stream the majority are coarse bubbles have an effective diameter in excess of 3 mm and rise at a velocity in the range from about 5 ft/sec to 10 ft/sec (1.5 m/sec to 3 m/sec), the improvement comprising,interrupting scrubbing gas while said aerator is flushed with a flushing liquid only;periodically injecting flushing liquid into said aerator through a conduit means connected thereto within an injection period of less than 5 min so as to flush said aerator's plenum with a single phase of flushing liquid flowing laterally therethrough in a mass flow sufficient to cleanse fouled air orifices in said aerator;maintaining flow of said flushing liquid for less than 5 min; and,returning loosened solid deposits from within said aerator into said substrate; and,re-establishing flow of said scrubbing gas.