CARBON DIOXIDE BIOFIXATION BY Chlorella sp. IN A BUBBLE COLUMN REACTOR AT DIFFERENT FLOW RATES AND CO2 CONCENTRATIONS

Abstract CO2 biofixation of the microalgae Chlorella sp. for different CO2 concentrations and gas flow rates in a bubble column reactor has been investigated in this study. Microalgae were cultivated under different CO2 concentrations (at 1.75% and 9.45% v/v) and gas flow rates (at 30, 50 and 70 ml/min). The maximum specific growth rate of Chlorella sp. was obtained for the CO2 concentration of 1.75 % and the gas flow rate of 50 mL/min. The highest biomass productivity rate (at 0.17 g L-1 day-1) was for a sample with 1.75 % CO2 at a flow rate of 70 ml/min. Moreover, the results have shown that the specific growth rate and CO2 biofixation have a direct relation with culturing of Chlorella sp. Also, limiting CO2 supplementation noticeably decreased biomass concentration. Therefore, the results have shown that a high flow rate and low concentration of CO2 might promote a decrease in CO2 fixation efficiency by Chlorella sp.