Periodical changes of input air flowrate - a possible way of improvement of oxygen transfer and liquid circulation in airlift bioreactors

The influence of small bubbles on the behaviour of airlift reactors during citric acid fermentation was studied. The small bubbles formed up to 70% of the total gas hold-up, so their distribution strongly influenced the predi cted liquid circulation velocities. A periodically changing air flowrate co uld be used to significantly improve the oxygen transfer capacity of airlif t reactors. This could be achieved by the effective utilisation of the oxyg en content of small bubbles, which originated from the foam. A procedure ba sed on the evaluation of transient pO(2) and gas hold-up profiles was sugge sted for the determination of the period of sparging. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.