Can a laboratory scale bioreactor predict industrial scale hydrodynamic parameters of microorganism growth in stirred tank bioreactors (STR)?

There are many uses for biological materials in the biotechnological industry. By using cells, it is possible to produce various products. A common problems in the industrial manufacturing of these products are low yields in the transition from laboratory scale to industrial scale. Many of these biotechnological processes rely on cell growth in stirred tank bioreactor (STBR). When process are cared out in industrial size STBR there is usually a decrease in the product and biomass yield. Experiments that lead to biotechnological processes are complicated to optimize, as they integrate conditions and parameters, which are defined by the specific organisms used and hydrodynamic parameters that are defined by operational parameters. To overcome challenges in up-scaling of STBR, there is a need to better characterize the process in the laboratory small scale STBR. Experimental bioreactor data as well mathematical, computation and simulation programs need to be integrated in order to identify critical hydrodynamic parameters necessary for scale up processes.

In this study the effect of different operational parameters in a laboratory, one liter STBR on the dissolved oxygen (DO) distribution and on the dispersion of E. coli was examined, experimentally and by The Visimix program. Results show that, in all of the operational condition examined the dispersion of E. coli was homogenous caused by an airlift effect by the flow of oxygen into the bioreactor, even without stirring. This was opposed to an uneven distribution of dissolved oxygen in all the operational condition examined. From the Visimix results we can see that the simulations resemble the results of the experiment, but it is not unequivocal whether the laboratory bioreactor can serve as a model for the industrial bioreactor