Ultra-thin rotating disk gas diffuser (and bubble shearing method employing the same)

A rotating gas diffuser for shearing fine gas bubbles from the surface thereof when the diffuser is immersed in a body of liquid and rotated therein, which comprises:

• a hollow rotatable shaft, said shaft defining a main feed line for the gas to be introduced into said body of liquid,
• a disk like member mounted on said shaft perpendicular to the axis of rotation thereof, said member defining at least one gas plenum in operative connection with said main feed line, at least one wall of said plenum being porous to permit the passage of gas through said wall to the outer surface of said disk like member so that the introduction of gas into said main feed line when the gas diffuser is rotating about its axis of rotation while immersed in said body of liquid will cause gas to flow into said gas plenum and out through said porous wall thereof to produce nascent gas bubbles on the surface of said disk like member, which nascent bubbles are sheared off to form fine gas bubbles by the viscous shear forces exerted by said liquid as the disk member rotates in said body of liquid, and
• means for minimizing the coalescence of said fine sheared bubbles, resulting from turbulence in the wake and jet surrounding the rotary disk like member that is caused by vortices shed from the edge of the disk like member and spiraling outward from said edge, said means including said disk like member, wherein the ratio of the overall diameter of said disk like member to the maximum thickness thereof in the gas diffusing area occupied by said gas plenums is at least about 32:1.