This project seeks knowledge of how to optimally bring the suspended living organisms from small-scale biotechnology-laboratories to large-scale flowing systems found in industrial production. This includes, among other things, that we seek understanding of how liquids with complex and special properties behave in flowing systems. Furthermore, it is also important to understand how gas bubbles behave in such liquids, as the supply of components such as oxygen is vital to the suspended living microorganisms in aerobic processes.
The PhD research fellow in the project has completed a 6-month stay at Chalmers University of Technology. The PhD student studies turbulent properties in canonical and complex flows with shear-thinning behavior through direct numerical simulations. The research fellow has two articles accepted in a prestigious journal in fluid dynamics (Journal of Fluid Mechanics), another article in press, and an articles is scheduled to be submitted in October 2021.
The postdoctoral fellow in the project has completed a one-year stay at Imperial College London. In collaboration, experimental studies of flows in pipe tanks with shear-thinning liquid are performed. These data will be compared with CFD simulations performed in the project. The postdoctoral fellow has also conducted experimental studies of mass transfer and bubble dynamics in stirred tanks with shear-thinning liquids. Two articles have been published, one article is being considered for publication, and another publication is drafted. The project has received a personal invitation to give a speech at an international conference on industrial biotechnology.
The project collaborates with researchers in Colombia on CFD simulations of bubble hydrodynamics in stirred tanks and non-Newtonian fluids. Two publications are currently being drafted.
The results so far indicate that the method and hypotheses in the project will provide a valuable and new understanding of flow in bioprocessing.
In this project, the young project manager will establish a new research activity at NTNU with the aim of enhancing the national knowledge on optimal design, operation and scale-up of bioreactors. Research effort that will enable realization of economical viable bioprocessing plants is necessary to ensure that Norway becomes a leading country in the green shift with significant bio-based industry.
In particular, this project addresses challenges related to fluid flow in bioreactors. Non-Newtonian fluids will be considered because such rheology is common in bioreactors and these types of fluids induce different and more complex flow behavior compared to Newtonian fluids. Most bioreactors contain multiphase flow systems which induce challenges with optimal operation related to bubbles such as interfacial mass transfer and gas holdup. This project will provide fundamental understanding of bubble size distribution (BSD) and its influence on gas holdup - a key step for the industry towards more optimal and safe operation of digesters. In contrast to previous studies of aerated bioreactors, interfacial mass transfer fluxes will be investigated with detailed information on the interfacial area through BSD data. Unlike the traditional approaches for turbulence characterization, this project will develop a new fundamental method to investigate details of turbulent vortices such as their three-dimensional structure, size, tilting, stretching and how they dissipate. A significant achievement is obtained in this project if the turbulent characterization of non-Newtonian fluid flows can explain trends in BSD and mass transfer data during scale-up, because such knowledge of turbulence will help to enable the necessary improvements in bioreactor performance.
The project will establish a strong and multidisciplinary research group that has the best possibilities to produce new knowledge necessary to bring the society a step closer to the realization of significant bio-industry.