To facilitate the configuration of bioreactors – a key technology for the new food industry – GEA, a German corporation, mostly active in the food and beverages sector, has developed a digital twin for virtual testing prior to construction. The aim is to create an optimum growth environment for cultured cells, which behave differently in mass production volumes than at laboratory scale.
Developing higher-performance bioreactors is a priority for the GEA Center of Competence for Bioreactor Technologies due to an impending dramatic capacity shortfall on the bioreactor market. Validation of large-scale fermenters using a digital twin is a key step in ensuring optimal growth conditions and making it possible to take new food processes successfully to scale, the company said.
“A bioreactor is a vessel that has to function like a living body. Inside it, life develops under highly complex conditions. Working on an industrial scale, we have to make living organisms predictable, because we need reliable and replicable performance to go hand in hand with maximum productivity,” explains Daniel Grenov, product manager, Bioreactor Technologies at GEA. “A digital twin simulates the environment inside bioreactors in a wide variety of scenarios. This lets us precisely match the tank design and the mechanical configuration for fine-tuning parameters such as shear stress, temperature, nutrient and oxygen distribution to what the cells need.”
CFD improves bioreactor performance
The virtual bioreactor testing is based on computational fluid dynamics (CFD), which models the growth behavior of cells as well as the oxygen and nutrient delivery radii inside the reactor. “Experts estimate that, when scaling up bioreactors, uneven distribution of oxygen and nutrients inside the tank often leads to performance losses of up to 30%,” Grenov says.
Like all living organisms, cells locate near sources of oxygen and nutrients. Temperatures and pH levels are critical and the environmental conditions must be kept homogeneous. Conversely, a lack of oxygen or nutrients puts cells under stress, causing them to lose productivity or release growth-inhibiting metabolites when they live in a confined space for an extended period of time.
“So we can’t simply stir the tank more, because the resulting shear stresses might kill cells and, in large reactors, contribute to oxygen gradients – in other words, an uneven distribution of oxygen.” This risk can be banished by using CFD simulation and by calculating kinetic models, both of which are powerful product development tools. Combined with physical test rigs to measure bubble sizes, and equipment behavior, GEA optimizes the performance of large-scale bioreactors right on the drawing board.