In the bio refinery of lignocellulosic biomass, side streams are released, such as lignin and sugar-derived humins, a component with some common characteristics with lignin. In the EU project ZELCOR (Zero Waste Ligno-Cellulosic Bio-Refineries) a clever combination of biotechnological and chemical routes is used to convert this recalcitrant biomass in high-value end products.
In the processing of making paper and cellulosic ethanol from lignocellulosic biomass, lignin-rich streams are generated. Additionally, humins are the other type of side streams on which the project focuses. These are lignin-like furan polymers released, for example, in the production of furandicarboxylic acid from lignocellulose. ‘These humins are now being used for the generation of energy,’ says Richard Gosselink of Wageningen Food & Biobased Research. ‘We think we can develop more high-quality applications. Humins contain furan molecules that have already partially reacted to each other. We want to discover if we can convert it into fine chemicals through a combination of chemical and enzymatic catalysis and bioconversion.’
In addition, the possibilities will be explored for fractionating humins and lignins to get better product properties, such as improved UV stability and barrier properties of packaging materials. And finally, the potential for processing lignin and humins in industrial resins and in cosmetics will be investigated.
Bioconversion: termites as micro reactors
In the bioconversion route, French partners (UPEC, YNSECT and INRA) use termites gut as micro bioreactors. Gosselink: 'Termites can convert lignin and humins into chitin, a valuable substance that naturally occurs in crabs and is processed into cosmetics. We have to find out how to optimize this process. For example, humins under their liquid form are rather sticky and we have to develop a process allowing the termites to consume this feedstock without sticking together. But it definitely is a promising way to produce a high-quality product through bioconversion.’
Aim: large-scale production of biomolecules
The project ZELCOR has a duration of four years and is coordinated by the French research institute INRA. The aim is to achieve process layouts which could lead to large-scale production of biomolecules for packaging, cosmetics and fine chemicals. Gosselink: 'Part of the project is fundamental in nature, but we also focus on the development of end products. Then it's up to industry to bring the new technology to the market.'
ZELCOR must lead to more added value from lignocellulosic biomass and less valuable raw materials being wasted. Gosselink: 'It is therefore necessary to develop solutions for side streams that are less easy to exploit. That's exactly ZELCOR's goal: converting recalcitrant side streams into high-quality products.’