The aspirating nozzle has an inner nozzle that receives the recirculated mixed liquor and an outer nozzle where the atmospheric air and mixed liquor are mixed and discharged.  A submersible or dry pit centrifugal pump provides the high-pressure mixed liquor to the aspirating nozzle assembly's inner nozzle.  Here, the aspirator throat design converts the pressure head provided by the recirculation pump into a high velocity head through the aspirator throat. 

The resulting venturi effect creates a vacuum and draws atmospheric air through a standpipe down to the outer nozzle of the aspirator, where it is mixed with the pumped liquid.  The top of the standpipe rises above the basin mixed liquor with its top at least 10 inches above the top side water depth.  

We utilize a hydraulically smoothed, bell-mouthed primary liquid inner nozzle to achieve maximum velocity. As the high-velocity air/liquid jet stream discharges through the outer diffuser nozzle of the aspirator, the turbulence generated shears the air into fine bubbles.  These bubbles are carried with the jet stream into the mixed liquor in the basin.