Olive leaves upgrading applying a novel two-stage organosolv pretreatment: Techno-economic and environmental assessment

This research study evaluates the techno-economic and environmental performance of an olive leaves based biorefinery to produce antioxidants, bioethanol, and organosolv lignin. The biorefinery comprises processes such as organosolv extraction, organosolv pretreatment and simultaneous saccharification and fermentation, which were simulated in Aspen Plus v9.0. Experimental data were used to simulate the process, assuming a linear up-scaling. The techno-economic evaluation was carried out considering financial indicators such as net present value (NPV) and internal rate of return (IRR). The environmental assessment was done applying the life cycle assessment methodology. The results shows that 100 g olive leaves can produce 16.58 g antioxidant extract, 11.12 g organosolv lignin, and 2.85 g bioethanol. The proposed biorefinery was feasible at a processing scale of 30,000 t/y with a NPV of 47.9 million USD and an internal rate of return of 27.8%. The proposed biorefinery can be implemented in Jaén (Andalusia-Spain) based on the high amount of olive leaves produced in this region. Stillages are the most polluting waste stream of the process. The carbon footprint of the biorefinery was 1.13 kgCO2-eq/kg olive leaves. The application of the biorefinery concept revealed that olive leaves could be transformed into value-added products from a techno-economic and environmental perspective.