Biomass Pretreatment Strategies (Technologies, Environmental Performance, Economic Considerations, Industrial Implementation)

Agricultural wastes are the most abundant and renewable resources in the world. These wastes, commonly called lignocellulosic biomass, are composed mainly of cellulose, hemicellulose, and lignin. Both the cellulose and hemicellulose fractions are polymers of sugars and thereby a potential source for fermentation processes. Lignin can be used for many purposes, including production of chemicals, heat, and energy. Lignocellulosic biomass is recalcitrant to hydrolysis with cellulolytic enzymes. Therefore, a pretreatment step is necessary for the production of fermentable sugars. Various pretreatment methods, such as physical, chemical, physicochemical, biological, and combinations of them are available. Selection of the best pretreatment depends on factors as foreseen utilization of the main biomass components, efficiency in separation, environmental concerns, compatibility with subsequent fermentation, energy requirements, and costs that must be taken into account for commercial implementation.