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

Abstract

Abstract Trichoderma is a cosmopolitan fungus whose importance lies in its ability to produce metabolites such as enzymes from the biodegradation of cellulose-rich waste. 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, Reynolds number) and mass transfer (kLa) properties were characterized in a biphasic (water-air) and triphasic (Trichoderma ressei- basal minimum medium-air) systems. A degradation kinetics of newspaper in the airlift bioreactor in batch culture was realized. At day 20 the enzyme activities, biomass, residual cellulose, protein concentration and reducing sugar 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 and Reynolds number of 1757 depending on the hydrodynamics parameters. In addition, the theoretical kLa was compared and estimated with respect to the experimental values with a maximum error of ±20% acceptable based on the proposed coefficient of performance. The relationship between mass transfer and Reynolds number is essential to assess the scalability of our system for an optimal degradation of newspaper.