Carbon Dioxide Bio-Sequestration and Biomass Production for Energy Purposes During C. vulgaris Cultivation Powered by Real Exhaust Gases from a Municipal Thermal Power Plant

This study assessed the potential of Chlorella vulgaris to biosequester carbon dioxide (CO2) and produce microalgal biomass using real exhaust gases from a municipal heating plant. Experiments were conducted in vertical tubular photobioreactors (V-PBRs) in three series: a control with atmospheric air as the CO2 source (S1), exhaust gases containing SOx (S2), and fully desulphurised exhaust gases (S3). The highest productivity of C. vulgaris was recorded in S3, where 2120 ± 123 mg VS/L was achieved with an exponential growth rate of 281.0 ± 16.2 mg VS/L·d. The presence of SOx in the gases caused the culture to die off as early as day 8 of the cultivation cycle, resulting in a decrease in biomass concentration and acidification of the culture medium. In S2, compared to the other experimental series, significantly lower organic carbon, lipid, and sugar contents were also observed in the microalgal biomass. However, protein content remained stable regardless of the CO2 source tested. Carbon Dioxide Utilisation Efficiency (CO2UE) was 53.8% (S1), 24.1% (S2), and 41.4% (S3), respectively. The results indicate that the presence of SOx in exhaust gases negatively affects the growth and survival of C. vulgaris, while its removal improves both biomass productivity and CO2 sequestration efficiency. The research demonstrates the potential for integrating microalgae cultivation with industrial CO2 emission management.