The specific interfacial areas in two external-loop airlift bioreactor
s of laboratory and pilot scale were determined, mainly by the chemica
l reaction method (sulphite oxidation). The parameter studied in water
/salt and starch/salt solutions was greately affected by gas superfici
al velocity, A(D)/A(R) ratio, by H-R-H-D/H-D ratio and eta(ap), respec
tively. Correlations for the specific interfacial area in the two syst
ems, considering the effects of the above-mentioned parameters, were p
roposed.