engleski

Tubular Bioreactors-Mixing and Scale-up Procedure

Tubular bioreactors are characterized by plug flow and are proven to be suitable for continuous processes. Comparison between tank and tubular bioreactors shows that tubular bioreactors are characterized by simplified construction, increased surface/volume ratio and concentration gradients of broth components along the bioreactor. Main disadvantage of tubular bioreactors is a relatively low aeration capacity. Tubular bioreactors are suitable for various processes such as wastewater treatment the production of ethanol, organic acids, biopesticides and cultivation of animal cells and phototrophic organisms Horizontal rotating tubular bioreactor (HRTB) was designed as combination of a "thin layer' bioreactor and "biodisc" reactor. Its interior was divided by O-ring shaped partition walls that served as carriers for active biomass. Mixing investigations in HRTB were carried on for different combinations of process parameters by using temperature step method. The axial dispersion model and modified cascade models ("simple" and "spiral" flow model, respectively) were used to describe the mixing in HRTB. Comparison between these models showed that the "spiral" flow model was the most suitable for mixing characterization in HRTB. In order to incorporate the "spiral" flow model in semifundamental scale-up it was necessary to make relations between the adjustable model parameters and bioreactor process parameters expressed as dimensionless numbers. Mathematica1 equations which relate adjustable model parameters and dimensionless numbers were used for the formation of prediction systems for adjustable model parameters. The analysis based o different criteria selected the most suitable prediction system for mixing description in HRTB. This prediction system could be based as a part of bioreactor scale-up procedure.

tubular bioreactors; mixing; mathematical models; scale-up procedure

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