Biorefinery potential of Eucalyptus grandis to produce phenolic compounds and biogas

Abstract

Vanillin is widely known in the food industry as the main flavoring compound of vanilla. Its natural extraction from the seed is not enough to supply the worldwide vanillin demand; therefore, new chemical routes from biomass have been developed to satisfy the vanillin market. A biorefinery for forest waste valorization could be an opportunity to maximize the economic gains and reduce the environmental impact in an integrated approach. This work demonstrates the experimental production of vanillin and vanillic acid through black liquor oxidation, after alkaline pretreatment of Eucalyptus grandis W. Hill ex Maiden chips. Additionally, the remaining solid fraction was valorized by anaerobic digestion. The experimental yields in the oxidation stage were 4.37% and 2.14% (based on lignin) for vanillin and vanillic acid, respectively. The biogas productivity in anaerobic digestion was 163 mL·g volatile solids–1. These values were the basis for the process simulation to analyze the potential for an integrated biorefinery. From an economic perspective, the process is feasible at a minimal processing scale of 8.58 t·h–1. On the other hand, the environmental assessment concludes that the environmental impact is mainly affected by the CO2 and CH4 emissions from biogas upgrading.