Sustainable route to biodiesel via eco-friendly supercritical fluid extraction of lipids from heterogeneous and widely available organic fraction of municipal solid waste

The Organic Fraction of Municipal Solid Waste (OFMSW) can play a key role in the frame of a circular economy since it contains valuable compounds such as lipids which are beneficial for the production of biofuel. In this study, an efficient and eco-sustainable extraction method using supercritical carbon dioxide (sc-CO 2 ) to extract lipids from OFMSW is reported. This approach highlights the great potential of both OFMSW and Supercritical Fluid-based Extraction (SFE) versus already reported studies primarily focused on specific food-processing waste. The heterogeneous OFMSW generated in municipal areas, and often disposed of in landfills, is herein investigated as an abundant resource still suitable for sustainable valorization. Extraction parameters were explored using a Response Surface Methodology (RSM), allowing to achieve a lipid extraction yield of 19.25 % at optimal conditions (410 bar, 55 °C, 7.5 l/min). The result of the sc-CO 2 based method is comparable to Soxhlet extraction while also bringing about the advantage of extracting without using harmful organic solvents. Furthermore, extracted lipids were converted into fatty acid methyl esters (FAMEs) rich in long-chain alkyl products (C10-C18), with potential applications as biodiesel for use in the energy sector. This innovative approach not only valorizes OFMSW but also addresses issues related to the depletion of raw materials, contributing to the generation of eco-friendly products and promoting environmental sustainability via a zero-waste approach. • Lipids were sustainably extracted from real heterogeneous OFMSW using sc-CO₂. • Optimal SFE conditions achieved a lipid yield of 19.25% without toxic solvents. • Extracted lipids were converted into biodiesel with up to 93% FAME yield. • Extraction process was modelled using Gompertz and Sovová mass transfer equations. • The method supports zero-waste strategies and circular bioeconomy principles.