GAS-SPARGED BIOREACTORS FOR CO2 FIXATION BY DUNALIELLA-TERTIOLECTA

Two kinds of bioreactors, a bubble-column and an air-lift bioreactor, have been designed. The influence of operating conditions such as medi um composition, light intensity, carbon dioxide concentration in the f lushing gas, culture temperature, and gas flow rate, on photosynthesis of Dunaliella tertiolecta were studied using a chemometrics approach. The bubble-column bioreactor system was shown to be advantageous over the air-life because of a weaker intensity of hydrodynamic stress der ived from gas bubble dispersion and culture broth mixing. Optimal cond itions for carbon dioxide fixation or maximal growth rate were determi ned. The effect of hydrodynamic shear forces on the algal wall produce d by gas bubbling was identified as one of the most significant factor s for algal growth.