Performance of airlift bioreactors with net draft tube

Mixing and oxygenation in tower-type bioreactors are typically driven by gas movement, and as a result, these bioreactors have lower shear force as well as lower power requirement than other mechanically driven ones and therefore are attractive for industrial applications. This paper reviews the performance of a special tower-type bioreactor, the airlift bioreactor with net draft tube, developed by us, in several microbial fermentation situations. This type of bioreactor is equipped with a wire-mesh draft tube, which results in better liquid circulation and larger gas-liquid interfacial areas, and therefore produces much higher mixing efficiency and oxygen transport capability. As our data showed, the performance of this type of bioreactor in terms of mixing and oxygenation is substantially higher than that achievable by bubble column and conventional airlift bioreactors. Results from microbial fermentation experiments using this type of bioreactor also give evidence of the feasibility and superiority of this particular design.