Wet Explosion: a Universal and Efficient Pretreatment Process for Lignocellulosic Biorefineries

Lignocellulosic biomass resources especially agricultural and forests residues, perennial crops, farm wastes, and the organic fraction of municipal solid waste hold significant potential for the widespread production of sustainable fuels, chemicals and bioproducts worldwide. For biochemical conversion processes, deconstruction of lignocellulosic biomass into its components (cellulose, hemicellulose and lignin) for further microbial conversion has been a major challenge due to the recalcitrant nature of lignocellulose. Thus pretreatment is prerequisite for efficient hydrolysis of lignocellulose and cost for such treatment is currently about one third of the overall processing costs in a cellulosic biorefinery. Thus, the development of a more efficient and cost effective pretreatment method is crucial for the commercialization of lignocellulosic biorefineries. Wet explosion (WEx), a thermochemical pretreatment method with additional features of oxygen addition and explosive decompression, can be adjusted to different biomass feedstock and to subsequent bio-catalytic and microbial processes. The WEx pretreatment method has been successfully applied in combination with both microbial fermentation and anaerobic digestion processes using both agricultural and forest residues as well as manure fibers. Steam explosion, represents a related process to WEx treatment where high pressure is used but no oxygen is added. This process has been tested in demonstration scale while WEx is on its way to commercialization. Presented here is a summary of the basic concepts and parameters involved in WEx pretreatment.