Valorisation of food waste into bio-based polyurethane rigid foams: From experimental investigation to techno-economic analysis

Food waste (FW) constitutes a significant portion of municipal solid waste and thus requires proper treatment. A ‘waste-to-wealth’ concept, in this case, urges the valorisation of FW to produce value-added products, given that such waste contains significant quantities of diverse nutrients. While most of these efforts have been focused on the recovery of carbohydrates, this paper introduces an FW biorefinery scheme to valorise FW lipids (FWLs) into bio-based polyols for polyurethane rigid foams (PURF). Considering economic viability, cost-effective dosages of enzymes for FW hydrolysis were first investigated. Subsequently, the obtained FWLs were converted into bio-based polyols through stepwise epoxidation and oxirane ring-opening. Characterisation results showed that FW hydrolysis aided the development of FWL-derived polyols into PURF. Moreover, the obtained PURF exhibited excellent properties that are suitable for thermal insulation applications in the fields of civil engineering and appliances. A further techno-economic analysis demonstrated a promising profitability of valorising FW into PURF. Proven as material-intensive, critical cost drivers of the proposed valorisation scheme mainly included the price of the PURF and the chemicals required for the synthesis. The FW processing rate also significantly influenced the economic viability. By providing a successful valorisation pathway from FW to PURF and highlighting vital economic variables, this work aims to provide insights to promote the sustainable development of FW biorefineries and relevant bio-based polymer industries.