Biomethanization of agricultural lignocellulosic wastes: Pretreatments

Abstract

Agricultural lignocellulosic waste can generate serious environmental problems if not properly managed. Biodegradation, through anaerobic digestion, is a cost-effective strategy for biogas production. However, studies on the biodegradation of lignocellulose show that the substrate is recalcitrant to microbiological hydrolysis, which reduces the efficiency of converting organic matter into biogas. The main reasons are its complex structure and slow biodegradation. The appropriate performance of biomethanization suggests a deep knowledge of substrates composition. Typically, the composition is about 10–25% lignin, 20–30% hemicellulose and 40–50% cellulose. This book chapter will summarize the anaerobic digestion process and rate-limiting steps, compositional properties, focusing specially on pretreatment strategies applied to lignocellulosic biomass to improve methane yield, and overall anaerobic digestion performance. The most common pretreatments applied to organic substrates will be studied: physical, chemical, biological and the combination of them. Additionally, the new trends in pretreatments will be exposed.