Natural and artificial lakes are subject to accelerated anthropogenic eutrophication. Our laboratory has performed a large-scale experiment in 2005 to remove phosphorus from a model lake using periphyton on submerged artificial substrata.

Almost 7,000 m2 of a special TANGERDING nonwoven was exposed as artificial substrata in a eutrophic lake (trophic index 2.9) near Bonn to stimulate growth of periphyton. The periphyton colonizing the substrata competed successfully with phytoplankton and about 275 g of phosphorus was removed together with the substrata from the lake after six month exposure. This represents about 50% of the total phosphorus of the lake during circulation before restoration was initiated. One year after the experiment, the trophic status of the lake was still close to the reference state (trophic index 2.3, classified as “mesotroph”), indicating that lake restoration was successful and sustainable.

We conclude that large-scale exposure of artificial substrates to stimulate growth of periphyton is a promising, environmentally friendly and cost-effective novel method for lake restoration.

Contact: Michael Melkonian