Capability of carbon fixation in bicarbonate-based and carbon dioxide-based systems by Scenedesmus acuminatus TH04

Abstract

Carbon sequestration using microalgae can be performed from bicarbonate (a product of carbon dioxide capture) and/or carbon dioxide. To implement either process successfully, the capability of microalgal strains is the most important criteria. In this work, a thermophilic microalgal Scenedesmus acuminatus TH04 was investigated to optimize its growth and carbon fixation in bicarbonate-based and carbon dioxide-based reactor systems. Culture variables including temperature, light intensity, pH, and aeration rate, concentration of NaHCO3, Na2CO3, CO2 and triethylenetetramine (TETA) were examined. The S. acuminatus TH04 strain achieved the highest biomass production and bicarbonate fixation efficiency of 1.7 g/L and 100 %, respectively, with 4.2 g NaHCO3/L. In a single photobioreactor (PBR), the maximum biomass production and CO2 fixation efficiency of 4.7 g/L and 9.8 % were achieved under the optimal conditions of CO2 of 5% (v/v), aeration rate of 0.1 vvm, TETA of 5 mM and Na2CO3 of 50 mM. Remarkably, a sequence of ten PBRs increased CO2 fixation efficiency by S. acuminatus TH04 to 93.9 %. The S. acuminatus TH04 strain demonstrated a highly potential capability in simultaneous production of biomass and carbon fixation from HCO3− and CO2 as carbon sources.