PRETREATMENT OF LIGNOCELLULOSIC BIOMASS

Pretreatments for lignocellulosic materials include mechanical comminution, alkali swelling, acid hydrolysis, steam and other fiber explosion techniques, and exposure to supercritical fluids. These processes act by a variety of mechanisms to render the carbohydrate components of lignocellulosic materials more susceptible to enzymatic hydrolysis and microbial conversion. A variety of methods are effective on representative biomass feedstocks such as agricultural residues, herbaceous crops, and hardwoods. This chapter reviews pretreatment techniques, focussing on the importance of biomass structure and composition in determining pretreatment efficacy and the mechanisms by which different pretreatments act. The chapter concludes by recommending approaches for achieving further improvements in pretreatment technologies.