Application of tower bioreactors with forced circulation in biomass production

Abstract

Characteristic hydrodynamic parameters of three selected types of bubble-type column reactors with forced liquid circulation were studied experimentally. Application of these units for the fermentation process - production of fodder protein by continuous cultivation of Candida utilis yeast on the synthetic ethanol was tested. Two modifications of the column reactor with the ejector gas distributor and the bubble type tower reactor with the central tube and forced internal circulation of the gas-liquid dispersion were selected. Diameter of all three reactors used was 0.3 m. The volumetric mass transfer coefficient (kLa) and gas holdup (εG) were determined both for the standard water-air system and under actual fermentation process conditions. The effect of the inlet ethanol concentration and of the dilution rate on the cultivation characteristics was determined during the cultivation experiments. The obtained results have proved that the studied reactor types are suitable for fermentation. Equipment with the ejector gas distributor can be recommended even for processes with high requirements on the oxygen consumption, while by the proposed construction arrangement the undesired foam formation in the system was successfully eliminated.