Microalgal Culture Systems: An Insight into their Designs, Operation and Applications

Mixing is of paramount importance to microalgal cultures. There are various methods of inducing mixing in microalgal cultures; however, the type of mixing to be adopted would depend on various factors such as, the type of microalgal strain, type of culture system (i.e., open ponds or photobioreactors), scale of culture systems (i.e., small or large-scale cultures), as well as, on the environment where the culture is operated (i.e., indoor or outdoor type). In any case, mixing is mainly done to improve the mass transfer efficiency in the culture broth and to maintain efficient distribution of gases (air, oxygen, carbon dioxide, etc.) and nutrients. Furthermore, efficient mixing would improve the light utilization by the microalgal cells and thus, enhance biomass productivities. It is therefore, important to implement efficient mixing to maximize the potentials of microalgae during cultivation. This paper reviews some strategies to achieve mixing in microalgal culture systems, with more emphasis on photobioreactor designs, operation and applications.