Rheology of lignocellulose suspensions and impact of hydrolysis: A review

Tien Cuong Nguyen (1, 2) , Dominique Anne-Archard (3, 2) , Luc Fillaudeau (1, 2)

1 LISBP - Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés
2 FERMAT - Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts
3 IMFT - Institut de mécanique des fluides de Toulouse

White biotechnologies have several challenges to overcome in order to become a viable industrial process. Achieving highly concentrated lignocellulose materials and releasing fermentable substrates, with controlled kinetics in order to regulate micro-organism activity, present major technical and scientific bottlenecks. The degradation of the main polymeric fractions of lignocellulose into simpler molecules is a prerequisite for an integrated utilisation of this resource in a biorefinery concept. The characterisation methods and the observations developed for rheology, morphology, etc., that are reviewed here are strongly dependent on the fibrous nature of lignocellulose, are thus similar or constitute a good approach to filamentous culture broths. This review focuses on scientific works related to the study of the rheological behaviour of lignocellulose suspensions and their evolution during biocatalysis. In order to produce the targeted molecules (synthon), the lignocellulose substrates are converted by enzymatic degradation and are then metabolised by micro-organisms. The dynamics of the mechanisms is limited by coupled phenomena between flow, heat and mass transfers in regard to diffusion (within solid and liquid phases), convection (mixing, transfer coefficients, homogeneity) and specific inhibitors (concentration gradients). As lignocellulose suspensions consist of long entangled fibres for the matrix of industrial interest, they exhibit diverse and complex properties linked to this fibrous character (rheological, morphological, thermal, mechanical and biochemical parameters). Among the main variables to be studied, the rheological behaviour of such suspensions appears to be determinant for process efficiency. It is this behaviour that will determine the equipment to be used and the strategies applied (substrate and biocatalysis feed, mixing, etc.). This review provides an overview of (i) the rheological behaviour of fibrous materials in suspension, (ii) the methods and experimental conditions for their measurements, (iii) the main models used and (iv) their evolution during biocatalytic reactions with a focus on enzymatic hydrolysis.

Mots clés: fibre suspension; hydrolysis; lignocellulose; paper pulp; rheology; viscosity; yield stress

Domaines: Sciences du Vivant [q-bio]

Tien Cuong Nguyen, Dominique Anne-Archard, Luc Fillaudeau. Rheology of lignocellulose suspensions and impact of hydrolysis: A review. Filaments in Bioprocesses, 149, Springer International Publishing, 2015, Advances in Biochemical Engineering Biotechnology, 978-3-319-20511-3. ⟨10.1007/10_2015_323⟩. ⟨hal-01269476⟩