Comparison of different processing routes for the valorisation of olive tree pruning wastes

Abstract

Abstract In this work, two different bioprocess plants are economically compared using Aspen Plus process simulations based on information from literature. Olive tree pruning (OTP) wastes are used as the raw material in the processes which are valorised through two different processing plants. One biorefinery scheme consists of an initial steam explosion pre-treatment to further obtain three final products: ethanol, xylitol and antioxidants (steam explosion plant = SEP). The other one consists of an organosolv (ethanol and water) pre-treatment operation to finally ferment glucose to ethanol, co-producing catechol from lignin depolymerization (organosolv plant = OP). Both plants show similar equipment costs (43-47 M€). However, the first plant (SEP) manufacture three marketable products with lower ethanol production (6364.35 m 3 /yr) than OP (8118 m 3 /yr). In comparison, the production of xylitol (999.36 tonne/yr) and antioxidants (1214.46 tonne/yr) as co-products in the SEP are much higher than the catechol production (124.05 tonne/year) in the OP. As a result, much of the organosolv resulting lignin is burned to produce energy. Considering all costs and incomes in both plants, the SEP would attain a profitability of 20%, while the OP would be -7%.