EFFECT OF DIFFERENT PHYSICAL PRETREATMENT STRATEGIES ON THE BIODEGRADABILITY OF LIGNOCELLULOSIC MATERIALS

When lignocellulosic biomass is used as a substrate in anaerobic digestion processes, a pretreatment stage is always required to break the hard structure of the material and facilitate the attack of microorganisms and, with it, their degradation. Numerous methods have been developed to pretreat lignocellulosic biomass. Four of them: torrefaction, cavitation, pelletizing and extrusion have been comparatively evaluated in this article as ways to increase methane production through anaerobic digestion of two raw materials with different lignin content: barley straw and vine shoot. In addition, it was examined how these pretreatments and the nature of the feedstock influence the volatile fatty acid profiles that are generated during the digestion process. The cavitation of biomass milled at 0.25 mm was revealed as the most efficient pretreatment among those tested, increasing by 360% and 240%, respectively, the methane production for vine shoots and barley straw.