Investigation of carbonization process parameters to manage Japanese knotweed (Fallopia japonica) in the UK

Abstract

Japanese knotweed (Fallopia japonica) is an invasive and destructive floral species in the UK. It causes a significant problem to natural and built environments. Stems and/or rhizomes need to be burned before disposal in order to prevent further propagation [1]. This process has a high carbon footprint and a decrease is favored. Hence, carbonization of Japanese knotweed into char, bio-oil and syngas has been proposed. In this paper, carbonization has been demonstrated to be possible. Japanese knotweed can be separated into 2 main parts: stems and rhizomes. Both parts were characterized for their chemical, physical & thermal properties and subsequently carbonized between 300 to 800°C with the duration held for 1h and 2h. It was found that stable carbonization parameters occurred at 600°C with duration of 1h. At higher temperatures, no further formation of char, oil or gas occurred. The calorific values for Japanese knotweed stem char and bio-oil were 31.2 MJ kg-1 and 13.7 MJ kg-1, respectively, whereas those for Japanese knotweed rhizomes char and bio-oil were 31.7 MJ kg-1 and 23.3 MJ kg-1, respectively. Carbonization may therefore, be a viable bio-fuel option for the management of Japanese knotweed.