(503d) High Solids Loading Processing of Hydrothermally Pretreated Miscanthus x Giganteus for Production of Anthocyanins, Sugars and Lignin-Rich Residue

Miscanthus x giganteus is a widely recognized bioenergy crop that finds potential applications in a biorefinery for the production of a wide range of biofuels and biochemicals (Rivas et al., 2019). In this study we focused upon the lab-scale and pilot-scale bioprocessing of miscanthus at high solids loading for recovery of value-added products such as anthocyanins, microbial lipids and lignin-rich residue. Hydrothermal pretreatment was studied for recovering anthocyanins. The optimized pretreatment conditions (170 ºC, 10 min) led to a recovery of 94.3±1.5% w/w of the total anthocyanin content and also improved the enzymatic digestibility of the biomass, allowing recovery of 70.6±0.5% w/w of glucose at the end of 72 h of enzymatic saccharification. Based upon the lab-scale studies, the pretreatment step was scaled-up with 50 kg of miscanthus with 50% solids loading using a continuous pretreatment reactor (Cheng, Dien, Lee, & Singh, 2019) that led to a recovery of 70% w/w of total anthocyanins present in the biomass. The pretreated biomass was subjected to enzymatic saccharification at 10-50% solids loading using fed-batch operations. The highest sugar yields were obtained for 50% solids loading. The sugar concentrations of the hydrolysate were 140 g/L and 80 g/L for glucose and xylose, respectively. The hydrolysate was further used for the production of microbial lipids. While the residue left after enzymatic saccharification was found to be enriched in lignin that could further be diverted toward the production of aviation fuel precursors. Hence a detailed biorefinery concept was demonstrated by bioprocessing of miscanthus leading to the generation of multiple products.

References

Cheng, M.-H., Dien, B. S., Lee, D. K., & Singh, V. (2019). Sugar production from bioenergy sorghum by using pilot scale continuous hydrothermal pretreatment combined with disk refining. Bioresource Technology, 289, 121663. doi:https://doi.org/10.1016/j.biortech.2019.121663

Rivas, S., Vila, C., Alonso, J. L., Santos, V., Parajó, J. C., & Leahy, J. J. (2019). Biorefinery processes for the valorization of Miscanthus polysaccharides: from constituent sugars to platform chemicals. Industrial Crops and Products, 134, 309-317. doi:https://doi.org/10.1016/j.indcrop.2019.04.005