Gas sparger for a filtering membrane

A process for gas sparging a membrane module immersed in a liquid in a membrane system, the process comprising the steps of,

• a) immersing a sparger in the liquid, the sparger having a conduit with an outlet from the sparger and an inlet, the inlet in communication with a chamber defined by the sparger and adapted to hold a pocket of gas in the liquid, the conduit having a low point between the inlet and outlet;
• and,
• b) feeding gas into the sparger at a specified minimum rate sufficient to cause bubbles to emerge from the outlet at least once every 30 seconds;
• c) observing or calculating a membrane system operating parameter while operating the membrane system to withdraw permeate during a series of polling intervals;
• d) feeding gas into the sparger at a pre-selected increased rate in a subsequent polling interval if the membrane system operating parameter crosses a first specified threshold value while feeding gas into the sparger at the specified minimum rate in a polling interval;
• and,
• e) feeding gas at the specified minimum rate in another subsequent polling interval if the membrane system operating parameter crosses a second specified threshold value while feeding gas into the sparger at the pre-selected increased rate in another polling interval.