Chemical pretreatment in lignocellulosic biomass, anaerobic digestion, and biomethanation

Abstract

The current impacts of climate change necessitate the promotion and use of renewable energy sources to avert the growing environmental and health concerns emanating from fossil fuels. Lignocellulosic biomass (LCB) is a promising, renewable, and sustainable energy source based on its abundance and feedstock properties. Anaerobic digestion (AD) involves a biochemical process that can convert LCB to biogas through hydrolysis and biomethanation processes through the action of microorganisms such as methanogens and sulfate-reducing bacteria. The hydrolysis of LCB releases various reducing sugars, which are essential in the production of biofuels such as bioethanol and biogas, organic acids, phenols, and aldehydes. The resultant biogas can complement energy needs while achieving economic, environmental, and health benefits. Enhancement of the AD process for LCB to bioenergy can be realized through appropriate pretreatment capable of disrupting the complex lignocellulosic structure and freeing cellulose and hemicellulose from the binding lignin for enzymatic saccharification and fermentation. Determining the optimal pretreatment technique for AD is critical for the success of the LCB energy production process. This study evaluated the application of chemical pretreatment to the improvement of LCB digestion for bioenergy production. The study reviews the LCB characteristics, AD processes, and the role of various chemical pretreatment techniques such as acid, alkali, organosolv, ozonolysis, and ionic fluids. The findings of this study create an understanding of the action methods and benefits of different LCB chemical pretreatment techniques while highlighting the outstanding drawbacks that require divergent strategies.