Internal flat-plate airlift cylindrical reactor for the degradation of newspaper using Trichoderma reesei: characterization of hydrodynamics parameters

Abstract

Trichoderma is a fungus that can degrade cellulose-rich waste using enzymes derived from their cellular metabolism. For its growth, aerated bioreactors are used in submerged culture where oxygen is one of the elements that limits this process. The aim of this study was to characterize the hydrodynamics and mass transfer of an internal flat-plate airlift cylindrical bioreactor for the biodegradation of newspaper using T. reesei as a study model. Hydrodynamics (gas hold-up, mixing time, and the Reynolds number) and mass transfer (kLa) properties were characterized in biphasic (water-air) and triphasic (Trichoderma reesei- minimal basal medium-air) systems. Degradation kinetics of newspaper in the airlift bioreactor in a batch culture were performed. On day 20, the enzyme activities, biomass, residual cellulose, protein concentration and reducing sugars were 1421 IU L-1 CMCase, 8.02 g L-1, 2.19 g L-1, 0.0018 g L-1, 0.07 g L-1 , respectively. Finally, the overall kLa (triphasic system) was calculated to be in the range of 2.34-14.76 h -1 with a Reynolds number of 1757 depending on the hydrodynamic parameters. In addition, the theoretical kLa was compared and estimated with respect to the experimental values with a maximum error of ±20% which is acceptable based on the proposed coefficient of performance. The relationship between mass transfer and the Reynolds number is an important criterion in assessing an optimal degradation of newspaper on an industrial scale.