University of Adelaide researchers on Wednesday embarked on a three-year project to use sound waves to control blue-green algae in Australia's freshwater supplies.

Chief Investigator Carl Howard, from the University's School of Mechanical Engineering, said researchers would be testing different amplitudes and frequencies of ultrasound to control what is a growing worldwide water quality problem.

“We've already shown in laboratory tests that ultrasound is effective at neutralizing blue-green algae,” Dr. Howard said in a statement on Wednesday.

“We know it works but we don’t yet know the best frequencies, amplitudes and duration for the most effective, economic and efficient process.”

Dr. Howard said ultrasound at high amplitudes was already used for treating sewage and in other chemical processes but wasn’t practical for fresh water.

At high amplitudes it breaks down the cell walls of the blue- green algae, releasing toxins into the water.

“The novel part of our solution is that we will be using ultrasound at low amplitudes where it immobilizes the blue-green algae without releasing its toxins into the water,” Dr. Howard said.

The researchers plan to mount ultrasound generators inside large underwater columns containing mixers which will draw the water through for treatment as it flows past.

Industry partner South Australia Water has been working with the university for 15 years on a range of chemical and water circulation techniques in reservoirs and the River Murray to help tackle blue-green algae.

The company's biology research leader said the latest project was an innovative and exciting development.

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