Multi-stage MFA for evaluating sustainable waste potential for bioplastics conversion in the circular economy: An examination of UK wastes to produce cellulose nanofibre

The negative environmental effect of petrochemical plastics prompts a shift in commercial interest towards bioplastics. Bioplastics produced from wastes and residues, when compared to primary biomass, reduces costs and emissions. However, these wastes are fed in alternative applications, resisting their use for bioplastics. The transition of wastes from current practices to bioplastics calls for a sustainability assessment, which is a combined examination of the economic, environmental and technical aspects. Material flow analysis (MFA), quantifying the flows of materials within a given system, is often used for waste management. However, MFA, not capturing additional waste characteristics, falls short in evaluating sustainable waste diversion. Therefore, this study suggests a Multi-stage MFA technique, integrating Multi criteria analysis (MCA) with MFA, to link additional information to the material flows, enabling sustainability assessment of waste to bioplastics conversion. To demonstrate the proposed methodology, this paper combines MFA with two particular MCA techniques, Analytic Hierarchy Process and Vector Space Theory, to analyse a UK case study of cellulose nanofibril (CNF) production. The findings indicate that, 11.6 Mt of the 18.04 dry Mt lignocellulosic wastes are sustainable for producing CNF films. However, this amount can change if the criteria or their relative importance in sustainability evaluation changes. The proposed approach is a generic tool for analysing sustainability of wastes to bioplastics conversion under a given geographic region to underpin circular economy. • Bioplastics produced from wastes reduces costs and emissions. • Wastes to bioplastics production necessitates combined sustainability assessment. • MFA is integrated with Multi criteria analysis to assess sustainability of wastes for upscaled bioplastics production.