Comparison of Chlorella vulgaris biomass productivity cultivated in biofilm and suspension from the aspect of light transmission and microalgae affinity to carbon dioxide

• Biomass productivity of microalgae biofilm is 30.4% higher than that of suspension.
• Number of cells that illuminated in biofilm was 16 times higher than in suspension.
• The microalgae showed a higher affinity to CO2 in attached cultivation system.
• CO2 saturation points of biofilm and suspension were 1.5% and 4.5%, respectively.

To investigate light transmission and cells affinity to CO2, Chlorellavulgaris was attached to microfiltration membrane that laid on the solidified BG11 medium compared to that in suspended cultivation mode in this study. The results showed that C. vulgaris showed a 30.4% higher biomass production (103 g m−2) in attached than in suspend system. The upper layer of biofilm with a thickness of 41.31 μm (the corresponding areal density of 40 g m−2) was effectively illuminated under light intensity of 120 μmol m−2 s−1 and more than 40% of the microalgal cells were in light even the areal density was high to 100 g m−2. While only 2.5% of the cells were effectively illuminated in the suspended cultivation system. Furthermore, microalgae cells in biofilm showed a higher affinity to CO2 compared with that in suspension, and CO2 saturation point of microalgae cells in biofilm was 1.5% but 4.5% in suspension.

Higher areal biomass density of Chlorella vulgaris was obtained in attached system than that in suspended system, due to its better light penetration performance and higher affinity to CO2.Figure optionsDownload high-quality image (108 K)Download as PowerPoint slide