Development of green extraction method of fatty acids from the Organic Fraction of Municipal Solid Waste (OFMSW) for the production of Biofuel

The valorisation of the Organic Fraction of Municipal Solid Waste (OFMSW) has garnered increasing attention as a sustainable approach to modern waste management strategies, promoting principles of circular economy while protecting the environment. In fact, traditional waste disposal methods, as landfills and incineration, are characterized by significant environmental impact, due to their production of soil and water pollution and the emissions of greenhouse gases. On the other hand, the valorisation of OFMSW not only solves waste disposal issues but it also provides products useful in different fields, since organic waste contains many high-value compounds, including lipids, polyphenols and antioxidants. On this ground, the present thesis investigated the development of an alternative green extraction method, based on the use of supercritical fluids (SFE), for the valorisation of organic waste by the extraction of compounds valuable in the energetic field, for the production of second-generation biofuel, contributing to renewable energy solutions and reducing reliance on fossil fuels. In particular, SFE was developed on the OFMSW and a specific organic waste, represented by Fishing Discards (FD), for the production of biofuel. In fact, FD is made up of unwanted catches, during fishing activities, that cannot be thrown back into the marine waters of Europe, as established by the reformed Common Fisheries Policy (Art. 15 of EU Reg. 1380/2103) of 2019, resulting in organic waste. SFE allowed the efficient extraction of lipid compounds from both OFMSW and FD, having advantageous properties for their use as biodiesel, after their conversion into Fatty Acid Methyl Esters (FAMEs). Moreover, SFE was also investigated for the valorisation of specific organic waste derived from crops activities, as discarded leaves originated by Globe artichoke (Cynara cardunculus L. subsp. scolymus) crops. In particular, the versatility of SFE allowed also the selective extraction of bioactive compounds, mainly represented by polyphenols, from discarded Globe’s leaves, by adjusting the operating parameters while maintaining compound integrity. Therefore, SFE proved to be an efficient and innovative method for the valorisation of organic waste, offering a zero-waste solution into the waste-to-energy and waste-to-product strategies context, thereby supporting the transition to a circular economy.