Adsorption of furfural from torrefaction condensate using torrefied biomass

Torrefaction is a biomass energy densification process that generates a major byproduct in the form of torrefaction condensate. Microbial conversion of TC could be an attractive option for energy integration within torrefaction process. However, TC contains several compounds, such as furfural, 5- hydroxymethylfurfural and guaiacol that are inhibitory to microbes. In this study, for the first time, we reported detoxification of TC, by removing the major inhibitory compound furfural, using torrefied biomass (TB) and later used the detoxified TC for anaerobic digestion. The effect of varying TB production temperature (225–300 ⁰C), TB dosage (25–250 g/L), initial pH (2–9), and contact time (1–12 h) on furfural adsorption was studied with batch adsorption experiments. Mechanism of furfural adsorption on torrefied biomass was best represented by pseudo second order kinetic model. The adsorption of furfural and other inhibitory compounds on TB was likely a hydrophobic interaction. A maximum of 60% of furfural was adsorbed from TC containing 9000 mg furfural/L using 250 g/L of TB in batch adsorption. For, column (20 mm internal diameter and 200 mm bed height), the saturation time for furfural adsorption was around 50 min. Anaerobic digestion of the detoxified TC shows that the lag phase in methane production was reduced from 25 d to 15 d for 0.2 VSsubstrate:VSinoculum loading. The study shows that TC can be effectively detoxified using TB for microbial conversion and can efficiently be integrated within the torrefied biomass pellet production process.