AIRLIFT REACTORS: CHARACTERISTICS, APPLICATIONS AND DESIGN CONSIDERATIONS

TLDR

Aerosol‑lift bioreactors are emerging as a promising design for aerobic fermentations, yet the foundational knowledge required to predict their performance is only now beginning to develop. This review compiles observations from the authors and other investigators to construct a coherent understanding of airlift bioreactor design. The authors examine mixing, hydrodynamics, mass and heat transfer, and compare bubble columns with airlift systems to clarify key design principles. They note that gaps in knowledge limit confident design, that extensive work—especially on non‑Newtonian media—is still needed, but that airlift vessels have been shown to be technically feasible for a wide range of fermentations.

Abstract

Bioreactors of the airlift type are a promising design for aerobic fermentations. The basic knowledge required for understanding and predicting the performance of these reactors is only now beginning to emerge. In this review we present our observations and those of other investigators in an attempt to build up a coherent picture of airlift devices. All the major aspects—mixing and hydrodynamics, mass and heat transfer—in these reactors are considered. Comparisons between bubble columns and airlift systems are made where analogies, similarities and/or differences between them provide insight into airlift systems. Throughout, the areas of particular concern and those in need of further research in this field are mentioned. Extensive work on all forms of airlift reactors, particularly in non-Newtonian media—homogeneous and suspensions—remains to be done. Current knowledge does not permit airlift reactor design with a high degree of confidence. However, the technical feasibility of all types of fermentations—plant cell, tissue culture, bacterial, fungal, and those utilizing yeasts—in airlift vessels has been demonstrated.