Utilization of Canadian waterweed - from nuisance to source of raw materials



In Koillismaa-region many lakes have been invaded by a harmful alien species Canadian waterweed (Elodea canadensis). In Finland, it has spread besides Koillismaa also to the Southern and Central Finland. Waterweed is aggressively spreading via pieces of stems and buds. Waterweed invasion is obvious especially in clear water, shallow and slightly eutrophic lakes, ponds and slow-flowing rivers and large ditches.

Degradation of waterweed biomass after growing season is releasing large amount of nutrients and consumes the oxygen, which can further lead to eutrophication. Mass growth may be relatively short, but especially in eutrophic waters, it can last for decades. In Koillismaa region waterweed was first detected in 1999 in some small lakes. During the next ten years, it has spread almost throughout the Kuusamo area, forming massive stands also in relatively oligotrophic Lake Ala-Kitka.

Naturebased tourism and fisheries in Koillismaa region has suffered a lot of waterweed overgrowth. Removal of waterweed by seine nets or machines is relatively expensive. In addition, the removal of the waterweed in some cases may even promote spread of plant by small pieces and increase algae blooming. However, the removal of plant mass will significantly reduce amount of available nutrients.


The project aimed to find new ways to utilize the biomass of waterweed and boost business related to it. The project focused on water bodies under massive growth of waterweed. The project analyzed the chemical composition and biomass of the waterweed in water bodies representing different nutrient and mineral levels. Project included feasibility study regarding its use as soil improver, as well as value-added products, for example, as for animal fodder, nutritional use and cosmetics industries, as well as corporate interest and business opportunities. Results are largely applicable all over the country.

Planned project also tested harvesting methods and how to utilize waterweed in biogas production. Project investigated biomass composition of heavy metals, nutrients and trace elements for the different kind of water bodies. Additionally project investigated in detail the possibilities to utilize both biomass and reject of biorefineries as raw material for additional use. The project also explored interest and business opportunities among companies interested in utilizing waterweed or developing removal methods.

Final results of the project were compiled to a report describing the model how to remove waterweed and what are the possibilities to use water weed as raw material for different purposes.

Final report

Satu Maaria Karjalainen, Anna-Liisa Välimaa, Seppo Hellsten and Elina Virtanen (ed.) 2017.
Vesiruton hyötykäyttö biotaloudessa - järvien riesasta raaka-aineeksi. Elodea-hankkeen loppuraportti. SYKEra 18/2017. English abstract.


More information

Biologist Satu Maaria Karjalainen, firstname.middlename.surname.@ymparisto.fi 

Published 2017-02-20 at 15:17, updated 2021-05-31 at 15:31