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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Comparison of oxygen mass transfer coefficient in simple and extractive fermentation systems

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Viana Marques, Daniela de Araujo [1] ; Torres, Beatriz Rivas [2] ; Figueiredo Porto, Ana Lucia [3] ; Pessoa-Junior, Adalberto [1] ; Converti, Attilio [2]
Total Authors: 5
[1] Univ Sao Paulo, Dept Pharmaceut Technol & Biochem, BR-05508000 Sao Paulo - Brazil
[2] Univ Genoa, Dept Chem & Proc Engn, I-16145 Genoa - Italy
[3] Univ Fed Rural Pernambuco, Dept Anim Morphol & Physiol, BR-52171900 Dois Irmaos, PE - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Biochemical Engineering Journal; v. 47, n. 1-3, p. 122-126, DEC 1 2009.
Web of Science Citations: 11

Aeration and agitation are important variables to ensure effective oxygen transfer rate during aerobic bioprocesses: therefore, the knowledge of the volumetric mass transfer coefficient (k(L)a) is required. In view of selecting the optimum oxygen requirements for extractive fermentation in aqueous two-phase system (ATPS), the k(L)a values in a typical ATPS medium were compared in this work with those in distilled water and in a simple fermentation medium. in the absence of biomass. Aeration and agitation were selected as the independent variables using a 2(2) full factorial design. Both variables showed statistically significant effects on k(L)a, and the highest values of this parameter in both media for simple fermentation (241 s(-1)) and extractive fermentation with ATPS (70.3 s(-1)) were observed at the highest levels of aeration (5 vvm) and agitation (1200 rpm). The k(L)a values were then used to establish mathematical correlations of this response as a function of the process variables. The exponents of the power number (N(3)D(2)) and superficial gas velocity (V(s)) determined in distilled water (alpha = 0.39 and beta = 0.47, respectively) were in reasonable agreement with the ones reported in the literature for several aqueous systems and close to those determined for a simple fermentation medium (alpha=0.38 and beta=0.41). On the other hand, as expected by the increased viscosity in the presence of polyethylene glycol, their values were remarkably higher in a typical medium for extractive fermentation (alpha=0.50 and beta=1.0). A reasonable agreement was found between the experimental data of k(L)a for the three selected systems and the values predicted by the theoretical models, under a wide range of operational conditions. (C) 2009 Elsevier B.V. All rights reserved. (AU)