Power input and rheology measurements during sugarcane bagasse enzymatic hydrolysis
Tuesday, April 29, 2014: 12:15 PM
Grand Ballroom F-G, lobby level (Hilton Clearwater Beach)
Luciano J. Correa, Laboratório de Desenvolvimento e Automação de Bioprocessos (LaDABio) – Depto. Eng. Química, Universidade Federal de São Carlos, São Carlos, Brazil, Alberto Colli Badino, Department of Chemical Engineering, Federal University of Sao Carlos, São Carlos, Brazil and Antonio J. G. Cruz, Chemical Engineering Department, Universidade Federal de São Carlos (UFSCar), São Carlos, Brazil
The performance of two dual-impeller configurations (DIC) during enzymatic hydrolysis of sugarcane bagasse was investigated. The systems consist: DIC1 - turbine elephant ear down-pumping and up-pumping; and DIC2 - Rushton turbine and elephant ear up-pumping. Experiments were carried out in a conventional bench-scale baffled stirred-tank (3 L) using 10% WIS of steam exploded sugarcane bagasse (17 kgf, 205 oC, 20 min.) in 0.05 M sodium citrate buffer (pH 4.8, 50oC, 470 rpm) during 96 h. A commercial cellulolytic enzyme preparation with 10 FPU/g of dry biomass was used. The power consumption of each impeller configuration was experimentally measured by digital dynamometer connected to the motor which was freely mounted on a bearing in the cover of the vessel. Throughout the experiments samples were periodically withdrawn for glucose analysis (HPLC) and rheology assessment (digital rheometer). Measurements were made at 50oC as a function of shear rate (3.4-85.0 s-1). The slurry presents a pseudoplastic behavior. After 24 h the viscosity decrease becomes less abrupt in both experiments (shear rate > 20.4 s-1). During the first half hour a sharp power consumption decrease was observed for both configurations. Then these values reached a plateau. Although the initial power consumption of the DIC1 configuration (11.8 W) is higher than DIC2 (8.9 W) the energy consumed during the whole experiment (96 h) was 22% lower. DIC1 configuration produced 39.7 g/L of glucose (82.3% cellulose conversion) while the DIC2 produced 24.0 g/L of glucose (49.8% cellulose conversion).

Acknowledgments: CAPES, CNPq and FAPESP for financial support.