ABSTRACT
Energy recovery from lignocellulosic biomass (LCB) is a popular and reliable approach, but it has several challenges. A techno-economic difficulty is observed due to the rigidity of LCB. As a result, most lignocellulose-based bioconversion processes, whether thermochemical or biochemical, entail pretreatment as an indispensable initial step. This is because the major elements of the LCB, i.e., cellulosic and hemicellulosic polysaccharides are assembled in an intricate complex along with the lignin polymer. No specific component is easily available for its chemical or enzymatic bioconversion. The pretreatment disrupts the lignocellulosic structural organization such that its subsequent processing is efficient. The structure opened by the pretreatment becomes more accessible and digestible. The pretreatment may even cause fractionation of specific components, which is important for biorefineries. The wide-ranging methods known for biomass pretreatment are broadly categorized as physical, chemical, thermochemical, or biological methods. Each method is unique in its benefits and has its own mechanisms, applications, and challenges. The preference for a specific method depends on the type of biomass and several other factors. This chapter discusses important aspects of conventional as well as advanced pretreatment methods known for biomass pretreatment.
