Advanced pretreatment processes for lignocellulosic biomass to biofuels production: Path towards circular bioeconomy

Abstract

Generation of biofuels obtained from lignocellulose biomass as a source can fundamentally decrease energy requirement from the conventional fossil fuels and their consecutive environmental effects. Circular bioeconomy concept has been established in the recent years for effective waste management which is the current need required to mitigate the deterioration of the environment. For that matter lignocellulosic biomass has been taken as a substrate for the fuel energy generation. In that regard, cellulosic ethanol as a substitute is likely to be able to grow as a feasible energy source in the upcoming future. For the last couple of decades, massive work has been performed to build cellulosic ethanol as an economical source with respect to the conventional nonrenewable source of fuel. The pretreatment step plays a significant role to break down the recalcitrant structures and to improve accessibility of cellulose to enzymes. An extensive amount of pretreatment techniques that involve physical, chemical, biological, and combined approaches have been adopted to test at the pilot scale. These techniques provide significant opportunities to lower the total cost, thus making large-scale production of cellulosic ethanol possible. This review discusses about the waste management with circular bioeconomy, various pretreatment techniques along with the mechanism of those pretreatments and some advanced pretreatment methods, their advantages followed by their parametric studies. Also, there is a discussion on lignocellulosic biomass acting as an aide in circular bioeconomy.