Strategies and engineering aspects on the scale-up of bioreactors for different bioprocesses

Bioreactors are central equipment used in the majority of bioprocesses. Different models of bioreactors have been developed for different processes, which can be applied either for submerged or for solid-state fermentation. Scale-up involves the development of bioprocess in bench, pilot, and industrial scales. Optimal conditions are first screened and determined in the bench scale and so that the process can be transferred to a larger scale. This transferring requires the proper reproduction of conditions and performance, being a major challenge since important aspects, such as aeration and agitation, are critical for cells development. In this case, scale-up strategies are employed to maintain bioprocesses’ performance. These strategies are based on geometric similarity aspects of bioreactors, agitation, and aeration conditions, which must follow the requirements of each bioprocess and the used microorganisms. Operational conditions significantly impact cell growth and, consequently, the biosynthesis of different biomolecules, which must then be reproduced at higher scales. For this purpose, one or more operating factors can be maintained constant during scale-up with the possibility to predict, for example, the power consumption of large-scale bioreactors or aeration conditions in an aerobic culture. This review presents the most employed bioreactors’ scale-up strategies. In addition, the scale-up of other bioreactors models, such as pneumatic and solid-state fermentation bioreactor and even photobioreactors, will also be described with some examples.