Biorefinery on mixed lignocellulosic feedstocks – a step towards valorization of mixed forestry residues for fostering biodiversity and forest resilience

Isolation of the three main polymers that constitute lignocellulosic biomasses is still challenging due to the complexity of the natural material and its chemical recalcitrance. In our ongoing efforts to improve biorefinery methods and to understand the implications of the process on structural features that determine downstream usefulness of the isolated polymers, we investigated a novel approach that involved mixed lignocellulosic starting materials in an organosolv processing. Till now, biorefineries used single types of biomass, i.e., only softwoods, hardwoods, or herbaceous plants. The reason for this lies in the already complex chemistries happening during biorefinery processes, and the understanding of product formation. Yet, such an approach is ultimately favoring monocultures in forestry, with drastic consequences for biodiversity and biological resilience of ecosystems. Yet, forestry monocultures are also a risk in light of the climate change that is increasingly affecting forests, necessitating the exchange of industrial forest monocultures into mixed soft- and hardwood forests. Such mixed forests will deliver, however, mixed biomasses for biorefineries. In our study, we used fir wood as standard softwood together with different hardwoods from various oaks to understand the effects in an ethanol-based biorefinery approach suitable for the valorization of mixed forestry products and wastes. Most interestingly, our results indicate a beneficial effect in terms of biomass fractionation, yielding high quality fractions of cellulose, hemicellulose and lignin. Separated fractions were fully analyzed according to the state-of-the-art. The truly novel isolated structural polymers represent valuable starting materials for the generation of innovative applications.