Study of the hydrodynamic parameters in an internal flat-plate airlift reactor for the increased degradation of newspaper by Trichoderma reesei.

Abstract

The aim of our study was to characterize the hydrodynamics and mass transfer in a novel internal flat-plate airlift cylindrical reactor to increase the biodegradation of newspaper. We evaluated the degradation kinetics of newspaper in a batch culture with Trichoderma reesei. Gas holdup, mixing time, the Reynolds number, and volumetric mass transfer coefficient (k_La) properties were characterized in biphasic and triphasic systems in order to optimize their operational conditions. An analysis of two effective factors in three levels including k_La, and Reynolds number (Re) were optimized by a full factorial design. Furthermore, a follow-up analysis of the ANOVA results p ≤ 0.05 was performed using Tukey's rank test method for p-value corrections. The overall k_La (triphasic system) was calculated to be between 2.34 and 14.76 h^-1 with an optimal value of 8.0 h^-1 (Flow: 3 L min^-1) and a Re of 1757. In addition, to show the optimal conditions, kinetic experiments were developed for 20 days using newspaper as carbon source for quantified the enzyme activities, biomass, residual cellulose, and reducing sugars 1421 IU L^-1 CMCase, 8.02, 2.19, and 0.07 g L^-1, respectively. The degradation rate of newspaper was over 80%, which was significantly higher than that of the nominal value. Finally, the theoretical correlation proposed for k_La was compared and estimated with respect to the experimental values with an error of ±20%. The k_La and the Re are important criteria in assessing an optimal degradation of newspaper in an industrial process scale-up.