Watercare fights blue/green algae with ultrasonic soundwaves


Watercare is trialling a new method of combating blue/green algae using ultrasonic technology in west Auckland’s Lower Nihotupu Dam.

All waterways, whether they are ocean beaches, streams, ponds or dams, are more susceptible to algal blooms as mid-summer approaches. There are many species of algae and while many are totally harmless (like spirulina) some can become toxic to mammals.

Watercare is believed to be the first company in New Zealand to use this ultrasonic technology from the Netherlands to monitor and eradicate this problem.

Water quality and environmental scientist Matt Hubrick says: “Ultrasonic technology is not new, but these devices combine on-site water quality instrumentation, solar panels, web-based software and ultrasonic emitters to create a much more advanced system of algal control with no detrimental effects to the environment.”

Five devices, called MPC-buoys as the monitor, predict and control algae, are floating on the Lower Nihotupu reservoir to provide total coverage. They are solar-powered and resemble small houses.

“They’re very selective as the frequencies of the ultrasonic emitters are altered in response to real-time water quality data to affect only target species,” Hubrick says.

“The targeted blue/green algae are crippled by the emitters which create a resonance that disrupts the algae cells, causing them to lose their buoyancy so they sink and slowly perish – much like a glass breaking from a high-pitched sound.

“This technique means blooms can’t form – a ‘prevention is better than cure’ approach.”

The devices are harmless to humans, animals, fish, aquatic plants and the natural environment. Non-target algal species are not affected.

“They are totally silent and unobtrusive, making them a great and somewhat futuristic way to control algae blooms with no negative effects,” Hubrick says.