Open AccessModeling of mixing in stirred bioreactors 4. mixing time for aerated bacteria, yeasts and fungus broths
Author(s) -
Dan Caşcaval,
AncaIrina Galaction,
Corneliu Oniscu,
Florina Ungureanu
Publication year - 2004
Publication title -
hemijska industrija
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.147
H-Index - 19
eISSN - 2217-7426
pISSN - 0367-598X
DOI - 10.2298/hemind0403128c
Subject(s) - bioreactor , aeration , mixing (physics) , fermentation , penicillium chrysogenum , biomass (ecology) , mycelium , continuous stirred tank reactor , microorganism , impeller , chemistry , materials science , bacteria , biology , botany , food science , thermodynamics , biochemistry , physics , genetics , organic chemistry , quantum mechanics , agronomy
The mixing time for bioreactors depends mainly on the rheoiogicai properties of the broths, the biomass concentration and morphology, mixing system characteristics and fermentation conditions. For quantifying the influence of these factors on the mixing efficiency for stirred bioreactors, aerated broths of bacteria (P. shermanii), yeasts (S. cerevisiae) and fungi (P. chrysogenum, free mycelia and mycelial aggregates) of different concentrations have been investigated using a laboratory bioreactor with a double turbine impeller. The experimental data indicated that the influence of the rotation speed, aeration rate and stirrer positions on the mixing intensity strongly differ from one system to another and must be correlated with the microorganism characteristics, namely: the biomass concentration and morphology. Moreover, compared with non-aerated broths, variations of the mixing time with the considered parameters are very different, due to the complex flow mechanism of gas-liquid dispersions. By means of the experimental data and using a multiregression analysis method some mathematical correlations for the mixing time of the general form: tm = a1*Cx2+a2*Cx+a3*IgVa+a4-N2+a5-N+a6/a7*L2+a8*L+a9 were established. The proposed equations offer good agreement with the experiments, the average deviation being ±6.7% - ±9.4 and are adequate for the flow regime Re < 25,000