Renewal of nanofibers in Chlorella fusca microalgae cultivation to increase CO2 fixation

• Nanofiber renewal increased the carbon assimilation by microalgae. • Nanofiber renewal in microalgal cultivation increased 23% the CO 2 biofixation. • An increase of 37.8% carbohydrates was found in cultivation with nanofiber renewal. • Microalgal cultivation with nanofiber renewal increased 62.8% the lipid content. This study explored strategies to increase the CO 2 fixation ability of microalgae by renewing polymeric nanofibers in cultures of Chlorella fusca LEB 111. Nanofibers composed of 10% (w v −1 ) polyacrylonitrile (PAN)/dimethylformamide (DMF) containing 4% (w v −1 ) iron oxide nanoparticles (NPsFe 2 O 3 ) were added to photobioreactors. The nanomaterial was renewed in the test cultures as follows: renewal only on day 7; renewal only on day 15; or renewal on both days 7 and 15 (i.e., double renewal). The highest biomass concentration (2.53 g L −1 ) and CO 2 biofixation rate (141.5 mg L −1 d −1 ) were obtained by cultivating with double renewal, resulting in values 21.6% and 23% higher, respectively, than those obtained by cultivation without renewal. The application of nanofiber renewal in the cultivation of C. fusca LEB 111 shows the potential to increase CO 2 biofixation, which may contribute to reducing the atmospheric concentrations of this main greenhouse gas intensifier.