ENZYMATIC HYDROLYSIS OF LIGNOCELLULOSIC BIOMASS: MODEL DEVELOPMENT FOR REACTOR DESIGN PURPOSES

Biorefinery processes for the production of second generation biofuels and bio-commodities are based on the use of waste lignocellulosic biomasses as a renewable feedstock. The sugar-based biorefinery platform includes biomass pretreatment and hydrolysis of structural polysaccharides as the first steps of the feedstock transformation. Hydrolysis of cellulose and hemicellulose in real biomass can be catalyzed by cellulase enzymes cocktails. The process has been developed up to industrial scale even though the scientific community is still active in investigating several critical issues in order to reduce costs of the process. The process allows obtaining a concentrated sugar aqueous solution (hydrolysate) from the heterogeneous conversion of the complex substrate (biomass) by the catalytic action of cellulases and beta-glucosidase dissolved in the liquid phase. The issues related to the reactor design include multi-scale phenomena affecting reaction kinetics, hydrodynamics as well as mass transfer of the biphasic system. The recent literature has been reviewed in order to highlight the state of the art about modelling of enzyme-catalyzed cellulose hydrolysis kinetics[1, 2], modelling of hydrolysis reactors[3], and optimization of process strategies[4]. Moreover, in the framework of the project Waste2Fuels (H2020-LCE-11-2015 g.a. n°654623), semi-mechanistic models of agro-food waste enzymatic hydrolysis have been assessed in order to obtain quantitative tools for bioreactor modelling. The effect of biomass pretreatment in terms of delignification degree has been quantified through the assessment of kinetic parameters of two agro-food wastes (apple pomace and coffe silverskin). References [1] Jeoh T., Cardona M., Karuna N., Mudinoor A.R., Nill J. (2017) Mechanistic Kinetic Models of Enzymatic Cellulose Hydrolysis--A Review, Biotechnology and Bioengineering, 114 (7), 1369-1385 [2] Bansal P., Hall M., Realff M.J., Lee J.H., Bommarius A.S. (2009) Modeling cellulase kinetics on lignocellulosic substrates, Biotechnology Advances 27, 833-848