Ljubljana, like many European cities, is faced with overgrowth of Japanese knotweed, one of the top 100 most invasive alien species in the world. Its rapid growth and strong, deep roots result in dense stands that quickly displace local vegetation and cause economic disadvantages.
In the past two years, the City of Ljubljana has offered its residents free deposition of removed Japanese knotweed in waste collection centres, before transferring it to an incinerator. Seeking to find innovative solutions to deal with this invasive plant and its further reuses, a design collective Re-generacija has shifted the perspective.
They initiated the idea and subsequent research into containing the spread of Japanese knotweed by recognising this undesirable plant as a locally accessible and abundant material for producing cellulose. Currently in Slovenia, the pulp and paper industry is using somewhere between 350,000 and 400,000 tons of cellulose, all of which is imported from abroad.
As part of promoting the title of European Green Capital 2016, the evolving initiative gathered five partners from different disciplines and sectors to test the first small scale industrial process of paper production from the widespread invasive plant. Approximately 100 volunteers and partners of the project were invited to take part in a series of urban harvesting actions organised by the City of Ljubljana, which included collecting 1520kg of Japanese knotweed stems.
Taking the advice from the University Botanic gardens in Ljubljana, the volunteers collected dry winter stems. In this way the new shoots of Japanese knotweed are weakened and the production process is shortened as the material doesn’t need additional drying. With the help of Snaga Public Waste Management Company the gathered materials were cut into smaller pieces and taken to the Pulp and Paper Institute where they were carefully processed into a final amount of 415kg of paper.
In addition to the manufacture of paper from Japanese knotweed on a semi-industrial scale, which in itself is a remarkable achievement, we are also pleased that alongside this, two very useful products have emerged, namely notebooks and paper bags, designed by the Re-generacija collective. In winter 2016 a campaign among vendors at the central open market in Ljubljana will be carried out, promoting the replacement of plastic with paper bags.
PROJECT PARTNERS: CITY OF LJUBLJANA, PULP AND PAPER INSTITUTE, SNAGA PUBLIC WASTE MANAGEMENT COMPANY, UNIVERSITY BOTANIC GARDENS LJUBLJANA AND RE-GENERACIJA COLLECTIVE.