Biomass producing and CO₂ capturing simultaneously by Chlorella vulgaris: Effect of CO₂ concentration and aeration rate

Optimizing the operational parameters of the photosynthetic process is essential for effective microalgae-based CO₂ capture and fixation. This study develops and validates models that can relate the effects of CO₂ concentration and aeration rate on relevant microalgal properties, including biomass productivity and CO₂ biofixation rate. The maximum biomass concentration was predicted as 2.80 g⋅L⁻¹ at the optimal CO₂ concentration of 10.2 % and aeration rate of 0.55 vvm. Based on the proposed models, the CO₂ biofixation rate characterized by carbon content in dry microalgal cells, and the timings of microalgae entering the exponential growth and stationary growth phases were effectively predicted. Furthermore, the lower heating value of harvested microalgal biomass was up to 21.98 kJ⋅g⁻¹ and the dominant fatty acid methyl esters (FAME) species were C16 – C18, highlighting the potential of Chlorella vulgaris as the feedstock for microalgae-based energy production. Consequently, microalgae present a remarkable dual function for CO₂ mitigation and renewable bioenergy production.