An overview of key pretreatment processes for biological conversion of lignocellulosic biomass to bioethanol.

Devendra Prasad Maurya,Sangeeta Negi,Ankit Singla

doi:10.1007/s13205-015-0279-4

Devendra Prasad Maurya, Sangeeta Negi + Show 1 more

Open Access

https://doi.org/10.1007/s13205-015-0279-4

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Journal: 3 Biotech	Publication Date: Feb 3, 2015
Citations: 419	License type: CC BY 4.0

Affiliation: Sam Higginbottom Institute of Agriculture

Abstract

Second-generation bioethanol can be produced from various lignocellulosic biomasses such as wood, agricultural or forest residues. Lignocellulosic biomass is inexpensive, renewable and abundant source for bioethanol production. The conversion of lignocellulosic biomass to bioethanol could be a promising technology though the process has several challenges and limitations such as biomass transport and handling, and efficient pretreatment methods for total delignification of lignocellulosics. Proper pretreatment methods can increase concentrations of fermentable sugars after enzymatic saccharification, thereby improving the efficiency of the whole process. Conversion of glucose as well as xylose to bioethanol needs some new fermentation technologies to make the whole process inexpensive. The main goal of pretreatment is to increase the digestibility of maximum available sugars. Each pretreatment process has a specific effect on the cellulose, hemicellulose and lignin fraction; thus, different pretreatment methods and conditions should be chosen according to the process configuration selected for the subsequent hydrolysis and fermentation steps. The cost of ethanol production from lignocellulosic biomass in current technologies is relatively high. Additionally, low yield still remains as one of the main challenges. This paper reviews the various technologies for maximum conversion of cellulose and hemicelluloses fraction to ethanol, and it point outs several key properties that should be targeted for low cost and maximum yield.

Highlights

The energy crisis in the early 1970s enforced research and development aimed at sustainable production of biofuels and chemicals from renewable lignocellulosic feedstocks of agriculture and forestry
Each pretreatment process has a specific effect on the cellulose, hemicellulose and lignin fraction; different pretreatment methods and conditions should be chosen according to the process configuration selected for the subsequent hydrolysis and fermentation steps
The objective of the present review is on the pretreatment processes and recent advances for bioethanol production from different lignocellulosic biomass, and to analyze the interrelated factors between pretreatment, hydrolysis and fermentation

Summary

Introduction

The energy crisis in the early 1970s enforced research and development aimed at sustainable production of biofuels and chemicals from renewable lignocellulosic feedstocks of agriculture and forestry. Lignocellulosic materials comprise a large fraction of municipal solid waste, crop residues, animal manures, forest residues and dedicated energy crops, providing the required attributes for reducing greenhouse gases emission (Wyman and Hinman 1990; Wang et al 1999; Sanchez and Cardona 2008). Crystalline polymer of b-D-glucose unit, and the structure is rigid and difficult to break (Chesson and Forsberg 1988). This cellulosic fraction can be converted into glucose by enzymatic hydrolysis or by chemical methods (Mosier et al 2005)

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