(216d) Innovative Design to Transform Waste Valorization through Co-Processing of Lignin and Residual Saccharides (CLARS) in an Integrated Biorefinery

Authors: 
Liu, Z. H., Texas A&M University
Ragauskas, A. J., University of Tennessee
Yuan, J., Texas A&M Univrsity
Lignin valorization is essential for the cost-effectiveness and sustainability of lignocellulosic bioenergy and modern biorefinery. Given the accessibility of lignin, the second-most abundant organic polymer, efforts are underway to valorize lignin to value-added products to make a sustainability of biorefineries. Despite the significance and progress, it is still unclear how lignin chemistry can be tuned and how different components of biorefinery waste can contribute to bioconversion. We hereby designed an innovative biorefinery configuration through co-processing of lignin and residual saccharides (CLARS) to improve the valorization of biorefinery waste. This innovative biorefinery configuration has improved both carbohydrate release and lignin solubility and reactivity. Upon this process, glucose and xylose yield was 91% and 73%, respectively, which was 18% and 12% higher than that using single pretreatment only. More than 85% of lignin was dissolved into a liquid stream, which was 69% higher than that using single pretreatment only. Additionally, over 70% residual saccharides in solid wastes were released from biorefinery wastes. Lignin stream was subsequently used for the production of polyhydroxyalkanoates (PHA), a source of energy and a carbon store in bacteria, by Pseudomonas strains. With fed-batch cultural mode, a record level of PHA titer (1.5 g/l) was achieved using lignin as a carbon source by Pseudomonas putida KT2440. Lignin characterization results suggested that the innovative biorefinery design significantly decreased the lignin molecular weight, broke down the β-O-4 and β–5 linkage groups, and enriched the H-type lignin content. Taken together with the increased residual sugar in a waste stream, the innovative biorefinery design significantly improved lignin conversion to PHA. As a result, this innovative biorefinery design improved the carbohydrate release, the residual saccharides utilization and the lignin processibility to PHA, which provided a unique set of features to deliver a sustainable biorefinery process.