In the scale-up of bioreactors one of the most 1 commonly used criteria for
aerobic processes is to keep the oxygen transfer coefficient constant. Nev
ertheless, the reproduction of the behaviour of a cell population at differ
ent scales is not dependent just on the oxygen transfer capability but rath
er on the oxygen transfer rate, that must be high enough to cope with the o
xygen demand of the culture. In this work a strategy of scaleup is proposed
based in geometric similarity, constant impeller tip speed, and constant o
xygen transfer rate. The effects of the dissolved oxygen concentration, the
scale-up ratio and the rheology of the broth are analysed.