The oxygen mass transfer represents the most important parameter implied on the design and operation of mixing-sparging equipment of the bioreactors. It can be described and analyzed by means of mass transfer coefficient, kLa. The kLa values are affected by a lot of factors, such as geometrical and operational characteristics of the vessels, media composition, type, concentration and microorganisms morphology, biocatalysts properties. The efficiency

The previous works on simulated broths are continued and developed for Propionibacterium shermanii broths. The obtained results indicated the considerable increase of kLa in presence of n-dodecane as oxygen-vector and the existence of a certain value of hydrocarbon concentration that corresponds to maximum mass transfer rate of oxygen. The magnitude of the positive effect of oxygen-vector strongly depends on operational conditions of bioreactor,

The efficiency of oxygen transfer into the fermentation broths could be enhanced by adding in broths oxigen-vectors, such as hydrocarbons or fluorocarbons, without increasing the energy consumption for mixing or aeration. The experimental results obtained for simulated, P. shermanii and S. cerevisiae broths indicated the considerable increase of kLa and (kLa)V /(kLa)0 by adding n-dodecane, but the magnitude of this effect must be correlated with

The comparative study on reactive extraction of nicotinic acid with Amberlite LA-2 and D2EHPA in three solvents with different polarity indicated that the extractant type and solvent polarity control the extraction mechanism. Thus, the reactive extraction with Amberlite LA-2 in low-polar solvents occurs by means of the interfacial formation of an aminic adduct with 3 or 2 extractant molecules. If solvents with higher polarity are used, each reactant

The study on mixing distribution for an aerobic stirred bioreactor and simulated (solutions of carboxymethylcellulose sodium salt), yeasts (S. cerevisiae) and fungus (P. chrysogenum pellets and free mycelia) broths indicated the significant variation of mixing time on the bioreactor height. The experiments suggested the possibility to reach an uniform mixing in whole bulk of the real broths for a certain value of rotation speed or biomass concentration