Gravity Aerator - How it Works

The Gravity Aerator is technically known as the ‘Downflow Contactor’. It mimics the natural aeration process that occurs when water flows over a waterfall or weir.

Click image for Interactive Demo - "How the Gravity Aerator Works"

The Gravity aeration process is explained below:

• The liquid is raised to a head of around 0.5 meters and stored in the inlet reservoir.
• If the supply has this head, then the aeration process requires zero energy.
• Then the liquid flows over a curved surface with an increasing gradient.
• The geometry of the curved surface reduces the need for a much larger vertical surface thus reducing the pumping head and energy demands.
• The liquid then flows down the vertical surface of a contactor column.
• As the liquid flows over the curved surface and down the vertical column, air is entrained within its outer surface.
• When the flowing liquid reaches the target liquid, the entrained air creates gas bubbles.
• A bubbly column consisting of an air/water mix is created that rises up.
• This rise is due to the bubbly column being lighter than the target liquid.
• The gas bubbles that are formed descend slowly with the faster moving liquid down the vertical column.
• The bubbles also continually change shape during their descent
• Their changing shape and slow descent allows the gas bubbles to release around 90% of their oxygen to the liquid.
• After descending 1.25 metres the water has obtained 90+% of all the oxygen available.
• The highly oxygenated liquid can then be either released to the target liquid or directed to any other point in the tank.
• Air bubbles are also released into the liquid but they have little oxygen left to transfer.
• Dependent upon the oxygen requirements of the liquid this cycle can be repeated a number of times.