Gas hold-up in external-loop airlift bioreactors

A new model of gas hold-up is proposed for external-loop airlift bioreactors. It is based on the similarity between the liquid circulation due to the local variation of gas hold-up in airlift bioreactors and the natural convection due to temperature difference. The model is developed to include the case of non-Newtonian fermentation media which are involved in many industrially bioprocesses. The capability of the model is examined using a wide range of experimental results including the present data. Reasonable agreement is obtained between the proposed model and the experimental data both for Newtonian and non-Newtonian media.