New frontiers in the recycling of waste vegetable oils: A research project for the circular economy

World coordinator Politecnico di Milano proposes innovative, cyclical and sustainable processes for the Waste Oils Recycle and Development Project to transform used vegetable oils into valuable resources.

The study was published in RSC Sustainability and rewarded for its originality by being featured on the cover.

The goal of the global project is to optimize waste vegetable oil treatment processes while improving the quality of the final product, reducing waste and promoting European independence in the supply of critical raw materials.

In fact, vegetable oils are widely used all over the world, and cooking and food preservation produces a huge amount of waste oil. Approximately 4 million metres of second-hand vegetable oil is produced in Europe each year, accounting for just 4% of the world’s volume of this rich, extensive product. If not properly disposed of, this waste can have a major environmental impact.

The World Project proposes recycling second-hand vegetable oils, creating innovative materials used as fine chemical constituents from biolubricants, air purifiers and petroleum-free precursors. These applications are presented as a supply chain in parallel with well-known uses in the production of biodiesel, but this is limited to 10% by law, and only the purest proportion of waste is of concern.

In addition to economic and technical benefits, the project will have strong social and environmental impacts. By raising awareness of correct collection of waste oil, we can reduce public costs associated with incorrect disposal and prevent environmental damage.

Additionally, life cycle analysis (LCA) is carried out to assess the best strategies to minimize ecological, economic and social impacts by adopting a zero waste approach.

“We started by observing that the waste oil recycling industry is currently based on simple decantation and filtration processes without proper scientific optimization. Therefore, we analyzed two alternative technologies: cleaning to improve efficiency and reduce environmental impact,” explains Andrea Mele of G. Natta Deartion of Millan.

“We optimized key parameters such as temperature, pH, bentonite concentration, and oil-to-water ratio through an experimental approach based on the design of experimental (DOE) methodology and multivariate statistical analysis,” continues Alberto Manne, who recently moved from Politics DI Milan to the Department of Mechanical and Industrial Engineering at the University of Brandsia.

“The results showed that washing with 75°C and pH 6 water ensures the best performance in terms of yield, productivity and environmental sustainability, minimizing the carbon impact of waste production and processes.”

Today, thanks to the World Project, mathematical models developed using collected data provide the recycling industry with practical tools to optimize processes in line with environmental certification standards, providing the recycling industry with comparable CO2 emission forecasts, depending on operational conditions.

This scientifically validated approach illustrates a step forward in the transition to a more efficient and sustainable circular economy. It forms part of the key principles of green chemistry, opens up new perspectives for sustainability and efficiency, and is highly competitive from a technical/economic perspective of the model of circular economy.