Ac. Badino et al., Improving k(L)a determination in fungal fermentation, taking into account electrode response time, J CHEM TECH, 75(6), 2000, pp. 469-474
An alternative way for determining the oxygen mass transfer coefficient, k(
L)a, based upon the traditional dynamic method, is proposed. The oxygen mat
erial balance equation in the liquid phase is integrated after insertion of
the oxygen probe response time (first order type), and k(L)a values are de
termined by employing Marquardt's algorithm, considering as a weighting fac
tor the model's sensitivity with respect to k(L)a. Bench-scale fermentation
s of Aspergillus awamori, performed under different agitation (300-700 rpm)
and aeration conditions (0.2-0.6 vvm), were utilized for calculating k(L)a
values (0.0283-0.0874 s(-1)), employing three methods: two so-called tradi
tional, the gas balancing and the dynamic methods, and the one proposed her
e. The latter method is shown to be as reliable as the aforementioned metho
ds but is easier to apply when the oxygen level in the reactor is above the
critical value. (C) 2000 Society of Chemical Industry.