Adsorption of furfural from torrefaction condensate using torrefied biomass

Abstract Torrefactionis a biomassenergy densification process that generates a major byproduct in the form of torrefaction condensate. Microbial conversion of torrefaction condensatecould be an attractive option for energy integration within torrefactionprocess. However, torrefaction condensatecontains several compounds, such as furfural, 5-hydroxymethylfurfuraland guaiacolthat are inhibitory to microbes. In this study, for the first time, we reported detoxification of torrefaction condensate, by removing the major inhibitory compound furfural, using torrefied biomassand later used the detoxified torrefaction condensatefor anaerobic digestion. The effect of varying torrefactiontemperature (225–300 °C), torrefied biomassdosage (25–250 g/L), initial pH (2.0–9.0), and contact time (1–12 h) on furfuraladsorption was studied with batch adsorption experiments. The furfuraladsorption on torrefied biomasswas best represented by pseudo second order kinetic model. The adsorption of furfuraland other inhibitory compounds on torrefied biomasswas likely a hydrophobic interaction. A maximum of 60% of furfuralwas adsorbed from torrefaction condensatecontaining 9000 mg furfural/L using 250 g/L of torrefied biomassin batch adsorption. For, column (20 mm internal diameter and 200 mm bed height), the saturation time for furfuraladsorption was around 50 min. Anaerobic digestionof the detoxified torrefaction condensateshows that the lag phase in methane production was reduced from 25 d to 15 d for 0.2 volatile solid (VS) substrate :VS inoculum loading. The study shows that torrefaction condensatecan be effectively detoxified using torrefied biomassfor microbial conversion and can be integrated within the torrefied biomasspellet production process.