"Report date February 1972." "Research conducted by the Bowles Fluidics Corporation, Silver Spring, Maryland." Includes bibliographical references (pages 69-72). United States Environmental Protection Agency Contract No. Contract Number: 14-12-863.

An engineering investigation and evaluation of vortex devices as bubble makers for use in the removal of suspended solids from wastewaters was conducted. Specific objectives included the development and test of bubble makers capable of generating bubbles having mean diameters of about 100 microns with vortex devices having minimum liquid passageways of 1/4 inch or greater. Bubbles having a mean diameter of 80 to 85 microns, with virtually no bubbles greater than 130 microns, were successfully produced. This mean size and size range are substantially the same as bubbles produced by pressurized water processes at similar operating pressures. Bubbles were produced both by aspirating atmospheric air directly into the vortex unit, and by aspirating atmospheric air at the suction side of the pump, dissolving it, and precipitating it or effervescing it at the vortex unit. Sufficient data now exist, however, to design vortex systems for direct functional tests in conventional air flotation systems.