Fed-Batch Cultivation of Arthrospira platensis Using Carbon Dioxide from Alcoholic Fermentation and Urea as Carbon and Nitrogen Sources

To reduce CO2 emissions from alcoholic fermentation, Arthrospira platensis was cultivated in tubular photobioreactor using either urea or nitrate as nitrogen sources at different light intensities (60 μmol m−2 s−1 ≤ I ≤ 240 μmol m−2 s−1). The type of carbon source (pure CO2 or CO2 from fermentation) did not show any appreciable influence on the main cultivation parameters, whereas substitution of nitrate for urea increased the nitrogen-to-cell conversion factor (YX/N), and the maximum cell concentration (Xm) and productivity (PX) increased with I. As a result, the best performance using gaseous emissions from alcoholic fermentation (Xm = 2,960 ± 35 g m−3, PX = 425 ± 5.9 g m−3 day−1 and YX/N = 15 ± 0.2 g g−1) was obtained at I = 120 μmol m−2 s−1 using urea as nitrogen source. The results obtained in this work demonstrate that the combined use of effluents rich in urea and carbon dioxide could be exploited in large-scale cyanobacteria cultivations to reduce not only the production costs of these photosynthetic microorganisms but also the environmental impact associated to the release of greenhouse emissions.