PRETREATMENT OF LIGNOCELLULOSIC BIOMASS: A BRIEF REVIEW OF THE PRINCIPAL METHODS APPLIED

Abstract

Introduction:
The growth of global energy demand results in numerous environmental challenges and an energy deficit. In this context the biomass use ois a promising way to produce sustainable energy through anaerobic digestion with pretreatment stage included.
Objective:
To present a summary of the main pretreatment methods reported to improve biogas production from lignocellulosic materials, as well as an approach on clean solvent-based methods.
Materials and Methods:
The main used sources were doctoral thesis and research articles where pre-treatment techniques were used, as well as published previously reviews about this topic.
Results and Discussion:
The results reported by different authors in the use of pre-treatments are described, considering as fundamental aspects the variation in the structure and methane yield, which can be different between dissimilar biomass using similar conditions. The formation of inhibitory compounds is more likely when steam explosion and acid pretreatments are used, or when it is working under severe temperature and time conditions. Clean solvent-based methods increase lignin removal and are therefore promising for biogas production.
Conclusions:
The inclusion of a pre-treatment stage prior to anaerobic digestion process allows to obtain better methane yields, if a good process selection parameters is made.