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.

Keywords:
CO₂ biofixation; Greenhouse gas; Microalgae; Biomass production; CO₂ concentration