In 1.5 years, Japanese knotweed will be a circular resource

In a circular chain project BlueCity in Rotterdam, a consortium of four companies is going to work on a project with the Japanese Knotweed plant, which is currently burned or composted, to more circular use as a higher-value material in a year and a half, BlueCity says in a press release.

Green contractor GKB Group, studio Why Knot Design, paper expert Chayka and entrepreneur in valorizing contents from plants DubbelDoel Flora are committed to creating the local economic chain for Japanese Knotweed.

Japanese Knotweed

Japanese knotweed is a strong plant with several interesting, unique properties. Due to its strong growth, the plant is an invasive species and controlling it represents a high cost for parties in the Netherlands. Why Knot is a startup that uses Japanese knotweed to develop circular products: sheet material, shampoo and paint. Their mission is to make peace with Japanese Knotweed, by valuing the entire plant in a circular high-value way: from rhizome to woody biomass. 

There are at least 10 hectares of Japanese knotweed growing in the Rotterdam region, on land owned by municipalities, ProRail, water boards and the province. Despite years of controlling the plant, its presence in the Netherlands is growing steadily. The roots spread with moving soil, through flooding and digging in soil, during sewer maintenance, for example. At present, the plant is destroyed by burning or processed into compost, which by no means always destroys the rhizomes completely and thus allows Japanese Knotweed to spread further anyway.

Local approach

Green processor Groenverwerker GKB Groep has been working for years to reduce Knotweed in the Rijnmond region. They developed various innovations in collaboration with the City of Rotterdam so that the chippings can be processed safely. The rest of the companies will use this material in the next two years for product applications: design products by Why Knot, extraction of the lignin by Chayka and use of the fibers as peat replacement in potting soil by DubbelDoel Flora. Over the next year and a half, the consortium will find out what the best circular chain is.

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