Physical, Chemical and Biological Pre-treatment of Lignocellulosic Biomass for Biorefinery Applications

The generation of energy from fossil fuels contributes significantly to global warming. This may be mitigated by the use of renewable (bio-based) feedstocks. Second generation biofuels made in biorefineries that utilize agricultural residues and other lignocellulosic wastes as feedstocks reduce the dependency on food crops such as sugar cane (for bioethanol) and oil seeds (for biodiesel). Pre-treatment of lignocellulosic feedstocks is key for ensuring process efficiency from the substrate to the product. There are many pre-treatment methods, and method selection is incumbent on the type of feedstock and the downstream processes required to generate the final product(s). Product yields can be increased by integrating two or three pre-treatment methods. For example, by combining physical and/or chemical pre-treatment with ultrasonication. The content of this chapter is focused on describing various pre-treatment methods that are used to break down and/or hydrolyse lignocellulosic biomass. The discussion extends to both conventional and novel ‘green’ methods and includes the advantages and disadvantages of each method type. Possible solutions for overcoming some of these disadvantages are included.