Aeration system for defouling one or more liquid-filtration membranes

A pulse aeration system for mounting in a tank for use with an immersed filtration system, the pulse aeration system comprising:

• a chamber housing defining a chamber, the chamber having a flow path structure that defines a gas flow path having at least one gas inlet and a flow path outlet, wherein the at least one gas inlet includes at least one bottom gas inlet that is positioned proximate a bottom of the gas flow path, thereby rendering the gas flow path an open channel, and wherein the at least one gas inlet is directly fluidically connected to a gas feed conduit for transporting a gas into the gas flow path from a gas source,
• wherein the gas flow path includes a first flow path portion that extends downward downstream from a first end thereof, and a second flow path portion that extends upwardly upstream from the flow path outlet and downstream from the first flow path portion, the flow path structure defining a barrier that is fluidically between the first and second flow path portions,
• wherein the barrier has a barrier bottom that is positioned at a selected level in the chamber so as to permit a gas release event during which the gas is released up the second flow path portion from the first flow path portion, when a gas level of the gas in the flow path reaches below the barrier bottom,
• wherein the flow path outlet is positioned for release of the gas into the tank so as to defoul at least one filtration membrane in the tank,
• wherein the flow path structure includes a sludge outlet proximate the bottom of the gas flow path to permit sludge in the flow path structure to fall therethrough,
• wherein the chamber has a bottom that is open beneath the sludge outlet so as to permit any sludge that falls through the sludge outlet to leave the chamber,
• wherein the sludge outlet is a first retentate inlet thereby permitting retentate to enter the gas flow path, so as to break bubbles present in the gas from a first size into a second size that is smaller than the first size,
• wherein the at least one bottom gas inlet is positioned upstream from the barrier so as to release the gas up the first flow path portion outside of the gas release event, but is positioned proximate to the barrier bottom such that the gas that is transported into the gas flow path from the at least one bottom gas inlet during the gas release event is at least in part carried by a flow of gas and retentate in the gas flow path into and up the second flow path portion.