Techno-Economic Feasibility of Biomass Washing in 1G2G Sugarcane Biorefineries

There are still bottlenecks to be overcome for the feasible industrial production of first- and second-generation ethanol (1G2G EtOH). One of them is the pretreatment stage. Washing is a candidate strategy to remove lignocellulose-derived byproducts from pretreated biomass, in order to reduce the negative effects of furaldehydes and phenolic compounds in the downstream biochemical reactions. However, the effectiveness of the removal of these inhibitors is highly influenced by the operational conditions of the washing process. Here, evaluation was made of the techno-economic impacts of including a washing operation after hydrothermally pretreating sugarcane bagasse for 2G EtOH production in an integrated 1G2G biorefinery. Different washing protocols were tested, considering their effects on the enzymatic hydrolysis and fermentation, and experimental data were used for simulation of process scale-up. The removal of inhibitors improved the glucose yield by 40%, followed by an increase of ~ 30% in EtOH productivity. These findings showed that washing is a cost-competitive option for a 1G2G biorefinery, with a net present value for the industrial unit of ~US$ 2.3E + 8, which was the highest among the 1G2G scenarios analyzed.