Ultrasound combats algae growth

1 min read

University of Adelaide researchers are investigating the use of ultrasound as an environmentally friendly and cheaper alternative to controlling blue-green algae in fresh water supplies.

In collaboration with water industry organisations including SA Water, the researchers are starting a three-year project to find the best process for using ultrasound in large volumes of water to combat this worldwide water quality problem.

Chief investigator Dr Carl Howard, from the university’s School of Mechanical Engineering, said researchers will be testing different amplitudes and frequencies of ultrasound.

’We’ve already shown in laboratory tests that ultrasound is effective at neutralising blue-green algae,’ said Dr Howard.

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

Blue-green algae (or cyanobacteria) can affect health and causes other water quality and environmental problems when it accumulates and forms ‘blooms’ in fresh water. It is currently controlled by the application of chemical treatments.

Dr Howard said ultrasound, at high amplitudes, is used for treating sewage and in other chemical processes but hasn’t been practical for fresh water treatment. Ultrasound at high amplitudes 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 immobilises the blue-green algae without releasing its toxins into the water and with lower energy input,’ he added.

The researchers propose mounting ultrasound generators inside large underwater columns containing mixers that will draw the water through for treatment as it flows past.