Mixing Systems, Inc.  


7058 Corporate Way, Dayton, Ohio 45459, USA
Phone: 937-435-7227     Fax: 937-435-9200     E-mail: mixing@mixing.com

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Mixing Systems' approach to jet aeration takes advantage of all the factors which increase mass transfer rates while lowering operating costs. The jet aeration system is more effective than other aeration methods because the system utilizes multiple oxygen transfer zones. The jet system is ideal for gas/liquid contacting, blending, and solids suspension applications.

Click on the graphic to the right to view an animated version of a jet aerator in operation.

Double Nozzles

Jet aerators use the ejector method of contacting gases and liquids. The jet consists of a double nozzle arrangement. Each jet has a primary inner nozzle, an intermediate high shear mixing chamber, and an outer secondary nozzle.

Jet aerator in operationHigh Contact Zone Within the Nozzles

Oxygen transfer begins when a stream of recirculated liquid from the inner nozzle (blue arrows in illustrations) comes in contact with a stream of low-pressure gas (red arrows) creating an intense mixing action in the chamber between the inner and outer nozzles. The intimate contact between the gas and liquid streams results in micro-size bubbles (purple arrows).

High Pressure Zone at the Tank Bottom

Next, oxygen transfer continues as a plume of fine bubbles, from 0.1 to 1 mm in diameter, is ejected horizontally through the outer nozzle into the main tank volume. The horizontal travel of the plume maintains the gas/liquid transfer interface for a much longer period of time than conventional diffused air systems. This high pressure condition gives the gas bubbles a greater opportunity to dissolve in the liquid, increasing the oxygen absorption efficiency. In addition, injection of the plume into the tank volume thoroughly mixes the tank. The powerful movement of the expanding plume creates fine eddy currents in the surrounding liquid, thoroughly mixing the tank and keeping the MLSS solids in suspension. High velocity gradients form within the tank volume and enhance mixing and solids suspension. The gradients are of a random nature, insuring the uniformity of the aerated liquid and the thorough suspension of solids.

Buoyancy Bubble Rise

As the initial horizontal momentum of the plume dissipates, the micro-size bubbles, now 1 to 3 mm in diameter, rise to the liquid surface. The rising plume produces an airlift effect that further mixes the tank contents. The rising jet plume also creates good molecular dispersion, sending oxygen molecules to the microorganisms much faster. Such intimate mixing of reactants assures effective process operation.

Surface Agitation

To further enhance oxygen transfer, the liquid momentum near the tank surface draws the air bubbles from the tank surface and redistributes them throughout the tank volume. Since all aeration and mixing occurs below the surface, there are no mist or spray problems. There are also no icing problems because the jet aerators eliminate thermal stratification and prevent freezing.


Copyright © 2000 -
Mixing Systems, Inc.
7058 Corporate Way, Dayton, Ohio 45459, USA
Phone: 937-435-7227, Fax: 937-435-9200
E-mail: mixing@mixing.com