Carbonate-enhanced cultivation of microalgae biofilm on the bovine serum albumin coated hollow fiber membranes

Microalgae has been commercially grown to support the growth of biorefineries. Since microalgae are commonly grown using carbon dioxide from the air during biofilm cultivation, their efficiency in capturing carbon from a liquid medium remains unclear. In this study, sodium bicarbonate (NaHCO₃) with varied concentrations was added as the additional carbon source during the cultivation of Navicula incerta on the bovine serum albumin (BSA)-coated hollow fiber membranes. N. incerta, a biofilm-forming diatom known for its surface adherence and environmental robustness, was selected for its suitability in the hollow fiber membrane cultivation system. The highest growth rate of 81.7 % was obtained by adding 8 g/L of NaHCO₃, with a harvesting efficiency of 81.02 %. The carbon fixation rate of 375.45 ± 15.89 mg˖L⁻¹˖d⁻¹ and carbon consumption efficiency of 58.91 ± 6.96 % were further attained. The chlorophyll content of N. incerta also increased from 2.61 ± 0.22–4.22 ± 0.28 mg/L. The microalgae biofilm on the BSA-coated PVDF hollow fiber membranes not only absorbed carbon dioxide from the air, but also removed the carbon source from the liquid.