Lignocellulosic BiomassLignocellulosic biomass is defined as a plant, or plant-derived, material that is mostly composed of cellulose, hemicellulose, and lignin. Lignocellulosic feedstocks are highly abundant, covering many biomass types including grasses, wood, energy crops (e.g. Miscanthus and coppices), agricultural residues (e.g. straws and corn stover), and municipal wastes.
Need for PretreatmentFor this reason, most hydrolysis technologies employ pre-treatment processes that aim to break apart the matrix (and in particular the associations between lignin and cellulose), reduce cellulose crystallinty, and hydrolyse hemicelluloses, hence separating the hydrolysate from cellulose which can then undergo more severe/targeted treatment.
Feedstock ChemistryThe chemical composition of lignocellulosic feedstocks varies greatly. This variability if seen not only in the relative proportions of the different polymers of lignocellulose (cellulose, hemicellulose, lignin) but also in the compositions of each of these polymers.
Lignocellulose FractionationSome pretreatment processes (e.g. steam explosion) focus primarily on a disruption of the lignocellulose matrix to allow for it to be more readily hydrolysed in downstream processes. However, other technologies (e.g. when using acids, alkalis, solvents, or hydrothermal pretreatment) involve the production of two (or more) process streams with the primary lignocellulose polymers (cellulose, hemicellulose, lignin) displaying a preference for one of these streams.
Downstream TechnologiesThere are different ways in which the output streams (solid and liquid) of the pretreatment process can be valorised. For example, the hemicellulose sugars that become separated into the liquid phase in a number of pretreatment processes (e.g. acid pretreatments and hydrothermal pretreatments) can be biologically-processed (e.g. fermented to ethanol) or chemically/catalytically processed (e.g. catalytic production of xylitol from xylose).
Commercial & Environmental ViabilityFor a bioprocess to be commercially-viable it is necessary for the revenues associated with it to exceed the operating costs and that these operating margins cover the CAPEX in a reasonable timeframe.
1. Understanding Your Requirements
2. Detailed Feedstock Analysis
3. Lab-Scale Pretreatments
4. Downstream Valorisation Experiments
5. Validation at Higher TRLs
6. Technoeconomic Analysis (TEA)
Pretreatment of Palm ResiduesCelignis undertook a bioprocess development project for a client, based in the Middle East, that was targeting the production of ethanol from the residues of local palm trees. This was a lab-scale vertically-integrated project covering pretreatment, hydrolysis, and fermentation.
Pre-Pretreatment ExtractionExtractives, if present in signficant quantities in the feedstock, can present a challenge to certain pretreatment technologies. For example, in organosolv pretreatments the extractives typically end-up in the liquid output stream of the process, along with lignin and hemicellulose sugars. At that point it can be hard to separate these extractives from the lignin meaning that the final lignin product may have a lower purity and, potentially, a lower market value.
Prodution of Oligomers from HemicelluloseCelignis undertook a bioprocess development project for a client where the focus was on the optimisation of process conditions to allow for increased yields of oligomeric sugars from the hemicellulose of an agricultural residue feedstock.
Pretreatment of Paper Industry ResiduesIn this project we worked with a client on evaluating processes for producing sugars in high yields from recycled paper streams. Along with other aspects, the project involved evaluating different process conditions for the selected pretreatment technology and then assessing the effect of these pretreatments on the subsequent enzymatic hydrolysis of the solids.
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From Process Refinements to an Entire New Process