Title : Integrating the complete value chain of the torrefaction process for effective biomass valorization
Abstract:
About 352 million tons of stubble are burnt on fields after harvest annually leading to
environmental pollution. If appropriately managed, abundant agricultural waste residues
from staple food sources (like rice/wheat husk and rice/wheat straw) could generate carbonneutral
and renewable commercial assets. Torrefaction, a simple thermochemical treatment
process, can effectively be employed to treat lignocellulosic biomass. Although several studies
have depicted the use of torrefaction for agro-waste treatment, the applicability depends on
the feedstock type, reactor design, operating conditions, economics, and quality of the
torrefied products. Torrefaction technology is mainly used to treat biomass to produce
biochar for heating applications. But biochar is a low value product. The recovery of highvalue-
added compounds from the biochar has never been carried out. The main aim is to
develop a biorefinery process by integrating central torrefaction technology and with biochemical
transformation to obtain high value products to make the whole torrefaction
process economically viable and environmentally sustainable for agricultural waste
utilization. In particular, 1) to fractionate rice husk, rice straw, and bamboo chips effectively
into hemicellulose, cellulose, and lignin, 2) followed by the separation of the cellulose and
lignin fractions present in the biochar through hydrolysis (acid, alkali, and ionic liquids) and 3)
to convert cellulose and lignin fractions through a cost-effective and green process to recover
5-HMF and vanillin efficiently. The torrefaction-derived value-added compounds (mainly 5-
HMF and vanillin) have many applications in the pharmaceutical, solvents, petrochemical, and
food-processing industries. The global markets of 5-HMF and vanillin were valued at 59
million USD, and 167 million USD in 2021. The global market for 5-HMF and vanillin is
predicted to reach 71 million USD and 735 million USD by 2025.
