Abstract: A fluid diffuser for dispersing a gas or liquid into a body of receiving liquid in which it is immersed. The diffuser includes a rotatable shaft, a thin disk-like member mounted for rotation on the shaft, and an annular ring positioned adjacent the outer perimeter of the disk-like member. At least one of the top and bottom walls of the annular ring is porous. These top and bottom walls define a fluid plenum, into which gas or liquid under pressure is introduced to be emitted from the plenum as small, nascent fluid spheroids on the surface of the annular ring. The boundary layer flow from rotation of the disk-like member within the body of receiving liquid shears fine gas bubbles or liquid particles from the foraminous surface or surfaces of the annular ring. The annular ring may be fixed, or rotatable in the opposite annular direction from the rotation of the disk. Impeller blades may be mounted on the top and/or bottom surfaces of the rotatable disk.

Abstract: A mixer for mixing a body of receiving liquid with solids, liquids or gases introduced therein. The mixer includes a rotatable shaft, a thin disk-like member mounted for rotation on the shaft, and at least one thin annular ring mounted on the disk-like member spaced from, parallel to and concentric with it. The flow of liquid perpendicular to the annular ring through the inner opening thereof, when the mixer is immersed and rotating in the body of receiving liquid, is unimpeded by any structural member. The annular ring may be mounted on either side of the disk, and a plurality of annular rings may be employed. The annular ring or rings may be mounted on the disk-like member by at least three elongated support posts spaced equally around the outer perimeter of the disk, the transverse cross-section of each post being curvilinear, preferably circular, in shape. The mixer is disclosed for use in a tank.