Effect of algal species and light intensity on the performance of an air-lift-type microbial carbon capture cell with an algae-assisted cathode

Abstract

The performances were investigated for air-lift-type microbial carbon capture cells (ALMCCs) with Chlorella vulgaris and Chlorella sp. as cathodic microorganisms. The two ALMCC systems showed differences in CO₂ fixation, lipid production and power generation. The ALMCC system with Chlorella vulgaris produced a maximum power density of 558.22 mW m⁻³, a CO₂ fixation rate of 223.68 mg L⁻¹ d⁻¹ and lipid productivity of 21.75 mg L⁻¹ d⁻¹, indicating that Chlorella vulgaris performed better than Chlorella sp. By conducting further experiments with Chlorella vulgaris under different light intensities (2.4, 5.0, 8.9 and 11.4 W m⁻²), the ALMCC was found to be sensitive to light intensities. The maximum power outputs and CO₂ fixation rate were observed under light intensity of 8.9 W m⁻² (972.5 mW m⁻³ and 887.8 mg L⁻¹ d⁻¹, respectively). The lipid productivity was increased with the light intensity from 2.4 to 11.4 W m⁻². However, there was no difference in lipid productivities between light intensities of 8.9 and 11.4 W m⁻² (p > 0.05). These results suggested that 8.9 W m⁻² was the optimal light intensity for CO₂ fixation, lipid production and power generation of the ALMCC with Chlorella vulgaris.