Used cooking oils, commonly referred to as WCO (Waste Cooking Oil), are derived from vegetable oils or animal fats that have been employed in food preparation and are no longer suitable for human consumption. Classified as special waste, they require proper disposal to prevent significant environmental damage. The Politecnico di Milano has developed an innovative, sustainable, and circular process that transforms waste vegetable oil into a valuable resource.
This initiative, known as WORLD, aims to optimize WCO management, enhance the quality of recovered products, reduce waste, and strengthen Europe’s self-sufficiency in accessing strategic raw materials. Under European regulations, WCO must be disposed of before reaching an advanced stage of decomposition to minimize the formation of harmful compounds such as acrylamide.
Early and proper disposal also allows for the recovery of waste with high industrial value. Biodiesel producers, for example, convert triglycerides into fuel for vehicles and aircraft. Additionally, used oils can serve in the production of eco-friendly paints, asphalt additives, and chain lubricants.
Each year, the European Union generates between 1 and 2.5 million tonnes of WCO, while global production ranges from 41 to 52 million tonnes. If not properly managed, this type of waste can severely harm the environment. When poured into sewage systems, it can clog pipes and contaminate water supplies—just one bottle of oil is enough to pollute thousands of liters of water. On land, it impedes oxygen absorption in the soil, threatening local ecosystems. Glycerol, a by-product of biodiesel production, is used in a variety of sectors including cosmetics, animal feed, and the chemical industry.
This versatility highlights the wide range of industrial applications for waste vegetable oils. The Politecnico di Milano proposes a novel recycling pathway that turns WCO into advanced materials such as bio-lubricants, air purification systems, and specialty chemical compounds—all derived from non-fossil precursors. These new applications represent an alternative to biofuels like HVO, which is restricted by regulations to 10% and relies only on the purest fraction of WCO.
Beyond the technological and economic aspects, the project has a strong social and environmental impact. It encourages the proper collection of used oils, reduces public spending on illegal disposal management, and helps prevent environmental degradation. A life cycle assessment (LCA) will be conducted to determine the most effective strategies for minimizing ecological, economic, and social impacts, following a zero-waste philosophy. According to Andrea Mele of the Department of Chemistry, Materials and Chemical Engineering “G. Natta” at the Politecnico di Milano, optimizing industrial processes for WCO treatment is essential to reduce environmental impact and enhance the sustainability of supply chains. Within the WORLD project, a mathematical model was developed to predict CO₂-equivalent emissions based on experimental data and varying operational conditions.
To achieve this, researchers adopted the Design of Experiments (DoE) methodology—a sophisticated statistical approach that enables more efficient experiment planning, reducing the number of trials needed to identify optimal operational conditions. Thanks to this data-driven approach and multivariate statistical analysis, critical parameters such as temperature, pH, bentonite concentration, and oil-to-water ratio were identified. The findings revealed that washing at 75°C and pH 6offers the best overall performance, maximizing efficiency and productivity while minimizing waste and the environmental footprint of the process.
