Blue-green algae successfully combated with hydrogen peroxide
The amount of blue-green algae in Lake Oosterduin in the province of South Holland has dramatically declined following an experiment with hydrogen peroxide. It is now safe to swim in the lake once again. The experiment was carried out by researchers from the UvA Institute for Biodiversity and Ecosystem Dynamics.
The researchers performed the treatment together with Arcadis on 16 June at the request of the Rijnland District Water Control Board. Highly diluted hydrogen peroxide was added to the water of the lake in order to combat blue-green algae. The results were a success, as the algae have almost completely disappeared. ‘The algae in question were Aphanizomenon, a genus of cyanobacteria we hadn’t combated with hydrogen peroxide before,’ says UvA researcher Petra Visser. ‘Combined with previous results we obtained in other lakes, it shows this method can effectively control a large range of blue-green algae species.’
Blue-green algae are bacteria which are naturally found in surface water. In large quantities they can form a floating layer and produce toxic substances. At the moment the amount of blue-green algae in the lake is very small, and not harmful to the health of humans or animals.
Research into combating blue-green algae
The effects of the treatment are expected to last for five to six weeks. The Rijnland District continues to keep a close eye on the water quality; it is possible that a second treatment may be needed later on in the swimming season. The experiment is part of a four-year research project. One important aspect of the study is to extend the duration of the treatment effects. The same treatment is planned for the nearby Klinkenberger Lake later this year.
The concentration of hydrogen peroxide added to the lake is low enough as to pose no risk to the health of humans, plants or animals. Only blue-green algae are susceptible and die off. As hydrogen peroxide breaks down completely into water and oxygen within roughly one to two days, the substance will leave no trace in the environment.
The experiment is a collaboration between the Rijnland District Water Control Board and the University of Amsterdam, Arcadis, Kemira, Waternet, STOWA, the municipalities of Noordwijkerhout and Oegstgeest and the province of South Holland. Funding is provided by Technology Foundation STW. The approach is coordinated with the Midden-Holland environment agency, which manages swimming activity in the lake on behalf of the province of South Holland.