SUEZ innovates for invasive plants management, preserving infrastructure, soil and biodiversity

Do you know the Japanese knotweed? This plant is cultivated in Asia, where it is renowned for its medicinal properties. It has also spread throughout Europe and is listed as one of the “100 world’s worst invasive alien species” according to the International Union for Conservation of Nature (IUCN). But it doesn’t have to be a disaster scenario: as part of its remediation activities, SUEZ innovates to manage it, preserving infrastructure, natural capital and biodiversity.
The Japanese knotweed are herbaceous perennial plants and members of the buckwheat family. They are fast growing plants spreading through their “rhizomes”, like roots, instead of seeds: during the summer, the plant grows rapidly, up to 10 cm a day. This asexual reproduction makes this invasive plant tricky to contain. Roots as small as 2 cm have been observed shooting and sprouting, leading to new areas being infested. They have also been observed breaking through asphalt and concrete, weakening or destroying buildings and foundations. They are also responsible for a loss of biodiversity. For this reason, quick and effective treatment is necessary.

Treating areas infested with this species requires care and precision. Many containment and/or treatment methods have been developed. These include herbicides, cutting and covering, continuous cutting of the stems and excavation… all with their drawbacks.
SUEZ is currently experimenting a new treatment method based on heat. This combines careful excavation of the infested area and a treatment of the knotweed containing soil with heat. The idea is to keep the roots at high temperature (60-80°C) until they are inactivated and unable to reproduce.

A pilot study into the specifics of this heating process is underway and the results are expected in the summer of 2021. After a successful pilot, testing will continue on a full-scale plant, hopefully leading to an operational plant going into 2022.