OXYGEN-TRANSFER IN A MULTIPLE AIRLIFT-LOOP REACTOR

The Multiple Air-lift Loop reactor (MAL) is a new type of bioreactor, in which a series of airlifts with internal loops is incorporated into one vessel. As such, the MAL is an approximation of an aerated plug-f low fermenter. Gas/liquid oxygen transfer was studied as a function of the gas flow rate in a MAL. The second MAL-compartment in the series was investigated in particular, and a Rectangular Air-lift Loop reacto r (RAL) was used as a reference. Both a dynamic and a steady-state met hod were used for the determination of the overall volumetric oxygen-t ransfer coefficient. Both methods gave the same results. The oxygen tr ansfer coefficient in the second MAL-compartment was low compared to t hat of conventional internal-loop reactors. Wall effects probably caus ed bubble coalescence and a reduction in the oxygen transfer. For the RAL it was found that oxygen transfer was comparable to that in a bubb le column.