Start With Load Not With Machines

Aeration capacity follows the oxygen demand of the process, normally expressed as kilograms of BOD per day for the stage being aerated. Only once that is known does a machine size mean anything.

A common mistake is to copy the aerator size from a similar plant. Two plants with the same basin volume can have very different loads.

Why Fine Bubbles Matter

Oxygen transfer depends on the surface area between air and liquid. A submersible aerator draws air down the pipe by the vacuum created between rotor and stator, and disperses it into bubbles of about 100 microns in diameter.

Small bubbles have far more surface area per unit of air than coarse ones, and they rise more slowly, which leaves more time for transfer.

See the SKCB Submersible Aerator specification →

Basin Geometry Decides Unit Count

Once capacity is known, geometry decides how it is divided. Deep compact basins suit submersible aerators. Wide shallow basins and lagoons often suit jet aerators, which drive a mixed stream across the surface area.

  • Basin volume and working depth
  • Length to width ratio and any baffles or corners
  • Whether the basin can be taken out of service for maintenance
  • Location of inlet and outlet, so the aerated zone covers the flow path
  • Existing aeration you are supplementing or replacing

See the Jet Aerator specification →

Aeration And Mixing Are Different Duties

An aerator adds oxygen and moves the contents. A submersible mixer only moves the contents, which is what anoxic zones, balancing tanks and sludge holding tanks need.

Plants that use aerators for mixing in unaerated zones waste power and upset the process. Specify the two separately.

See the Submersible Mixer specification →

Plan The Lift Before The Install

Units mounted directly on the basin floor without a guide rail can only be recovered by draining the basin. That turns a routine inspection into a plant shutdown.

Decide at design stage whether units sit on a fixed base, run on guide rails, or hang from a float. It costs little then and a great deal later.