Sustainability assessment of lignocellulosic biorefineries based on sequential pretreatments.

BACKGROUND: Pretreatments are critical in biorefinery analysis, affecting further reactions and downstream processes. However, most pretreatments are studied and optimized as single‐step schemes, focusing on maximizing a side stream. Sequential pretreatments have been shown to improve the selective isolation of platforms for further valorization. However, pretreatment performance can consider not only technical but also economic, environmental, and social concerns. This work assessed the sustainability of sequential pretreatments in rice husk‐based biorefineries. RESULTS: Four biorefinery scenarios were designed, simulated, and assessed considering dilute acid and wet air oxidation pretreatment technologies in sequential and single‐step schemes. Economic feasibility was demonstrated for sequential pretreatments when phenolic compounds are contemplated, generating gross incomes of 4.76 M‐USD yr−1. From an environmental perspective, the rice supply chain generated a carbon footprint of 2.17 kg CO2 eq kg−1 of rice husks, where the producer link is the largest contributor due to fertilizer use. Likewise, it was shown that supplying energy demands using black liquor as fuel relieves operating costs and reduces the carbon footprint. The social dimension showed that between 69 and 77 jobs could be generated annually along the value chain and the biorefinery schemes. However, biorefineries have a high risk due to the high volume of cooling water. CONCLUSIONS: All dimensions were weighted to calculate a sustainability index, where it was concluded that sequential pretreatment biorefineries improved sustainability against the single‐step schemes. However, the scenario of valorization of the three fractions (Sc1) is the best scheme to be implemented as it has always demonstrated economic feasibility. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]