Periodic Reporting for period 3 - Zelcor (Zero Waste Ligno-Cellulosic Biorefineries by Integrated Lignin Valorisation)
Periodo di rendicontazione: 2019-10-01 al 2021-02-28
Zelcor objective is to demonstrate the feasibility of transforming lignocellulose biorefinery recalcitrant side streams into high added-value biobased products by combining chemical and enzymatic catalysis with insects-based conversion. The project is conceived to avoid waste production by recycling waste bio-based products and improve the sustainability of existing second-generation biorefineries. Through a biorefinery-integrated approach, Zelcor aims to develop efficient and sustainable processes for large-scale production of biomolecules for cosmetics, packaging and chemical industry as well as novel biocatalysts. To reach this aim, the project implies the establishment of a platform for the characterisation of biomolecules along with the elucidation of the structure-function relationships and mechanisms involved in catalytic depolymerisation and bioconversion. Residues from cellulosic ethanol production, lignins from pulping process and lignin-like humins formed by sugars conversion are addressed in the project. All the targeted intermediate products are 100% biobased and obtained by processes driven by green chemistry. They are expected to be safer and more biodegradable than their fossil-based counterparts. Moreover, as biobased products obtained from industrial wastes, they are likely to reduce the total CO2 emission of the whole value chains.
Lignins and humins from four types of biorefineries were recovered at kilograms scale and implemented for comprehensive structural and functional characterization, including safety profiling, as well as for the development of processes. Variability of the raw materials was investigated and specific valorisation strategies were settled for each type of raw material. A fractionation step by water, organic solvent or alkali depending on the material, is beneficial to increase the functionality and/or yield of the intermediate products. Humins direct use in cosmetics was explored and their alternative possible conversion into organic acids demonstrated. Four main routes have been developed for lignin conversion: solvent extraction and treatment by an ionic liquid yielding antioxidant extracts, base catalysed depolymerisation yielding aromatic chemical intermediates, dissolution-aggregation technology to recover colloidal lignin particles and use of lignin as substrate for the production of biomass by insects. Termites species able to be reared at large scale and to digest lignin-rich substrates were selected and implemented for the creation of an innovative rearing system that made the breeding operations possible and led to the first production of chitin from termites. This innovation is under patenting. Recalcitrant lignocellulosic fractions were successfully used as carbon source for living termites or by microbial consortia cultivated from termite guts. Improvement of the environmental and health impact of these routes was achieved while scaling-up the processes. The possibility to use enzymes for lignin functionalisation was demonstrated (water-solubility increase by enzyme-catalysed sulfation and depolymerisation by tailored enzymatic cocktails). Sixteen new fungal and bacterial enzymes with activities on technical lignins were expressed and characterised, among which three were selected for large-scale production. All the technical achievements were integrated in a cross-cutting value-chain approach, aiming at providing valuable biobased products for targeted markets. A mapping of functionalities was established allowing selection of intermediate products for formulation and processing into skin-care cosmetic creams, packaging materials and aqueous colloidal systems. Down-stream functionalisation was successfully applied to intermediate products to tailor their properties in view of new markets. The performances of the end-products were confronted to the end-user's requirements and to techno-economic analysis in order to define the efforts requested to bring the applications and new technologies to the market. Zelcor results have been disseminated through 22 publications in international journals and communications in at least 13 international symposia. An electronic knowledge book has been built up which will be opened to public in 2021. The link between research, education and training was ensured through the involvement of 10 PhD students and Post-doc scientists in the project, the organisation of 2 summer schools and 2 webinars and the participation to various MSc programmes, including an Erasmus Mundus joint Master Degree (Bioceb).
A major advance has been made by offering technological solutions to recover higher-value products from biorefinery side streams so far mainly burnt. Some of the Zelcor compounds are potential new ingredients for the skin care/cosmetic sector, food packaging, and several applications of bioplastics. They have the advantage of being biobased and to combine several functional properties, including biological activity. Developing the value chains including these new products will help making biobased industry more economically viable and thus encourages the transition away from a fossil-fuel based society. The new knowledge on lignins and humins stability and variability will help develop flexible biorefinery processes. The production of new biocatalysts will promote the development of greener routes for lignin functionalisation. A range of bacterial and fungal lignin-oxidising enzymes and accessory enzymes are now available for testing as combined biocatalysts for lignin conversion. Association of lignin-degrading enzymes and accessory enzymes improves the yields and functionalisation degree. A novel enzyme enhancing lignin solubility has been discovered, which opens up new prospects of solvent-free processes. Advances made in the understanding of enzymes activities towards lignins will be useful also for other sectors. Progresses have been made in establishing structure-properties relationships and understanding the reactivity of lignins towards chemical treatments, in particular ionic liquid depolymerising treatment. Extraction of low-molar mass phenolics prior to the treatment improves the recovery yield of functional intermediate products, which highlights the interest of a cascade process combining solvent extraction and depolymerising treatments. Insights into the safety and eco-toxicity of the selected ionic liquid have been obtained and show that it provides an alternative non-flammable and recyclable reagent for sustainable processes. Using termites as natural biomass utilization systems offers possibility to develop cost-effective and energy-saving strategies for industrial side-streams conversion, especially though processes acting in more environmental-friendly conditions compared to chemical catalysts. The design of a termite bioreactor prototype represents a breakthrough that will allow to connect food and non-food value chains.