ORIGINAL PAPER Sugarcane bagasse enzymatic hydrolysis: rheological data as criteria for impeller selection Leonardo Tupi Caldas Pereira • Lucas Tupi Caldas Pereira • Ricardo Sposina Sobral Teixeira • Elba Pinto da Silva Bon • Suely Pereira Freitas Received: 1 June 2010 / Accepted: 19 August 2010 / Published online: 16 September 2010 Ó Society for Industrial Microbiology 2010 Abstract The aim of this work was to select an efficient impeller to be used in a stirred reactor for the enzymatic hydrolysis of sugar cane bagasse. All experiments utilized 100 g (dry weight)/l of steam-pretreated bagasse, which is utilized in Brazil for cattle feed. The process was studied with respect to the rheological behavior of the biomass hydrolysate and the enzymatic conversion of the bagasse polysaccharides. These parameters were applied to model the power required for an impeller to operate at pilot scale (100 l) using empirical correlations according to Nagata [16]. Hydrolysis experiments were carried out using a blend of cellulases, b-glucosidase, and xylanases produced in our laboratory by Trichoderma reesei RUT C30 and Aspergillus awamori. Hydrolyses were performed with an enzyme load of 10 FPU/g (dry weight) of bagasse over 36 h with periodic sampling for the measurement of vis- cosity and the concentration of glucose and reducing sug- ars. The mixture presented pseudoplastic behavior. This rheological model allowed for a performance comparison to be made between flat-blade disk (Rushton turbine) and pitched-blade (45°) impellers. The simulation showed that the pitched blade consumed tenfold less energy than the flat-blade disk turbine. The resulting sugar syrups con- tained 22 g/l of glucose, which corresponded to 45% cel- lulose conversion. Keywords Rheology of biomass slurries  Biomass enzymatic hydrolysis  Biomass reactor impellers  Power consumption List of symbols du/dy Shear rate N Rotation (r.p.m) D Impeller diameter H Height helpful T Tank diameter w Thickness pitched blade P Power g Apparent viscosity q Fluid density H Angle pitched blade g Gravitation constant N p Power number N Re Reynolds number Introduction Currently, there is a scientific consensus that the present trends and patterns of energy production and consumption are unsustainable. This poses to the worldwide scientific community a challenge to implement technological solu- tions to protect the environment and society from the adverse impacts caused by the continuous and intensive use of oil for power generation. In this context, the production This article is based on a presentation at the 32nd Symposium on Biotechnology for Fuels and Chemicals. Leonardo Tupi Caldas Pereira  Lucas Tupi Caldas Pereira  R. Sposina Sobral Teixeira  E. Pinto da Silva Bon (&) Chemistry Institute, Federal University of Rio de Janeiro (UFRJ), Avenida Athos da Silveira Ramos 149, Bloco A, Cidade Universita ´ria, Rio de Janeiro, RJ CEP 21941-909, Brazil e-mail: elba1996@iq.ufrj.br S. Pereira Freitas School of Chemical Engineering, Federal University of Rio de Janeiro (UFRJ), Avenida Athos da Silveira Ramos 149, Bloco E, Cidade Universita ´ria, Rio de Janeiro, RJ CEP 21941-909, Brazil 123 J Ind Microbiol Biotechnol (2011) 38:901–907 DOI 10.1007/s10295-010-0857-8