Autonomous device for algae control

Growth of blue-green algae (known as cyanobacteria) is a major problem in reservoirs, ponds and lakes, producing a foul odour and even toxins. These toxins can cause discomfort and illness, including skin irritation. They are also suspected of contributing to the occurrence of liver cancer.

Traditional means of controlling algae include aeration, the use of chemical or biological additives, and ultrasound. However, these are not sufficiently effective in larger water bodies and incur the high labour costs associated with frequent maintenance and dosage.

The EU-funded project CLEARWATERPMPC provided an answer to these problems using environmentally friendly technology based on ultrasound. Ultrasound is a well-known technology for combating algae; however, the CLEARWATERPMPC system is more cost effective due to low operation and installation costs.

Researchers developed a buoy system that can autonomously control algal blooms by monitoring and interpreting water quality parameters. The buoys work using an ultrasound signal based on the type of algae present in the water, which does not affect plants, insects or other life present in the water body.

Solar panels and batteries provide the buoys with sufficient power for continuous operation through the summer growing season. The power is distributed to the control unit and the ultrasound driver, which consumes most of the energy when transmitting high-power ultrasound signals.

The device's sensors are attached to submersible arms, which are lowered in to the water when the buoy is moored. The controller and sensors were integrated with the buoy and tested under laboratory conditions before the buoy was deployed.

Algal blooms develop fastest in the warmer parts of Europe, while Scandinavian countries use surface water more frequently for drinking water. Therefore, southern Europe and Scandinavia face the greatest challenge from blue-green algae and present the largest market for the CLEARWATERPMPC buoy system.