Natural fibers reinforced polymers, providing an environmental advantage, are increasingly used in a number of technical applications in which their functionalization (for example flame retardancy) may be required. This is expected to lead in a medium term to an significant amount of end of life functionalized biocomposites waste that have to be valorised. In this context, the objectives of WASABIO is to study and define how to manage the end of life of flame retardant biocomposites in order to ensure their sustainability. Flax/PLA composites obtained from commingled non-woven are considered in the project. Three different flame-retardant treatments will be studied in order to vary the weakness of the interactions (from weak interaction to covalent bonding) between the FR moieties and the flax fibres. Two recycling scenarios will be considered: mechanical recycling (mechanical recycling of plastics refers to the processing of plastics waste into secondary raw material or products without significantly changing the chemical structure of the material) and chemical recycling (chemical recycling, aims to convert plastic waste into chemicals). Innovative technologies including fluid (water and supercritical CO2) assisted-extrusion and catalytic co-pyrolysis will be developed. A life Cycle Analysis will be carried out on both FR treatments and recycling processes in order to evaluate the environmental impact of the different approaches studied in WASABIO. This approach will help to define the best solutions in term of design and recycling of FR biocomposites in order to make them as sustainable as possible. The transdisciplinary approach of WASABIO combining materials science and chemistry should result in fundamental knowledge that could directly benefit to the development of virtuous life cycle of functionalized bio-based materials. The expected impacts of the project are significant and concern at the same time economical, scientific and environmental aspects. The WASABIO project is part of an approach to reduce the environmental footprint of materials both by using bio-sourced materials and by proposing different end-of-life scenarios. The project is focused on two main scientific/technical barriers identified in the field of biocomposites: their functionalization (flame retardancy) and the management of their end-of-life. All the knowledge developed in WASABIO will contribute to the emergence of a sustainable and circular bioeconomy.