Page 275 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Agroresidue-based biorefineries
11

1
1
2
Raveendran Sindhu , Parameswaran Binod , Ashok Pandey and
Edgard Gnansounou 3
1
Microbial Processes and Technology Division, CSIR-National Institute of Interdisciplinary
2
Science and Technology (CSIR-NIIST), Trivandrum, India, Centre for Innovation and
Translational Research, CSIR-Indian Institute for Toxicology Research (CSIR-IITR),
3
Lucknow, India, Bioenergy and Energy Planning Research Group, Swiss Federal Institute
of Technology Lausanne, Lausanne, Switzerland

11.1 Introduction

Lignocellulosic biomass is a cheap and most abundant agroresidue, which is derived
from agroindustrial activities (Hay et al., 2013). They are generated as by-products
from harvesting and processing of agricultural crops. Readily available agroresidues
include straw, stalks, cobs, peelings, and bagasse (Li and Liu, 2012). Agroresidues
are generated in large amount and are the most abundant renewable resource in the
universe. Utilization of this resource for the production of value-added compounds
has several environmental and economic benefits.
Agroresidues are lignocellulosic complex mainly composed of cellulose, hemicel-
luloses, and lignin. The composition of the lignocellulosic biomass varies, depending
upon the species and age of the plant and also different parts of the plant such as
leaf, stem, stalk, and roots. It is mainly composed of cellulose, followed by hemicel-
luloses and lignin. It serves as the source of carbon, nitrogen, and minerals for the
growth of microorganisms for the production of different value-added products.
Most of the microorganisms cannot use agroresidues directly. Hence some kinds
of pretreatment have to be carried out for the removal of hemicelluloses and lignin
and to make cellulose accessible for enzymatic saccharification. Different types of
pretreatment currently in practice include chemical, physical, biological, and inte-
grated/hybrid strategies. A common strategy cannot be used for all agroresidues,
since the composition varies with species and variety. In the present scenario, most of
the reported hybrid strategies are not economically viable. Lots of efforts are going
on in this direction to develop economically viable processes with minimal or no
inhibitor generation as well as to develop a process that can be operated with less
energy conditions. Availability, collection, and storage of agroresidue are other major
concerns. Agroresidues can be considered carbon neutral, when they are primarily
used for power generation with lower emission of pollutant oxides. An overview of
different value-added products derived from agroresidues is depicted in Fig. 11.1.

Refining Biomass Residues for Sustainable Energy and Bioproducts. DOI: https://doi.org/10.1016/B978-0-12-818996-2.00011-9
© 2020 Elsevier Inc. All rights reserved.