Rereading my post, the ...
Published by George Hutchinson, President, AlgaeControl.US LLC
Rereading my post, the ultrasonic biofilm control project was in Port Orange, Florida, not Orange, Florida.
Ultrasound causes vibrations in the water that to anaerobic bacteria are similar to the sensation of turbulent water. They are genetically disposed to not colonize turbulent water zones, because they must emit a chemical to attract the aerobic bacteria that make up the thicker portion of the biofilm layer (80%) over the base layer of anaerobic bacteria. This cannot be done in turbulent water as the chemical is rapidly swept away.
Many times algae will use the biofilm matrix for either attachment or for nutrients.
For algae, ultrasound will damage green algae and diatoms using critical structural resonance to cause the inner cell wall (plasmalemma) to physically tear away from a pump (contractile vacuole) thus preventing proper fluid flow in the cell that kills it. This can kill attached algae in about 3-4 weeks.
In a tank, the ultrasonic effect on blue-green algae is less effective due to these algae passing through the tank quickly. It takes 3-4 days for blue-green algae to completely lose their buoyancy from the effect of ultrasound that crushes the internal gas vesicle walls (only a protein layer thick) and releases the gas into the cell where it slowly diffuses through the outer wall that is not make to hold it. For blue-green algae, the control is best done in a holding reservoir that will allow these algae to sink and slowly die from lack of light at the reservoir bottom.
George Hutchinson, President, AlgaeControl.US LLC