Arthrospira (Spirulina) platensis cultivation in tubular photobioreactor: Use of no-cost CO2 from ethanol fermentation

The present study aimed at evaluating the production of Arthrospira platensis in tubular photobioreactor using CO2 from ethanol fermentation. The results of these cultivations were compared to those obtained using CO2 from cylinder at different protocols of simultaneous ammonium sulfate and sodium nitrate feeding. Maximum cell concentration (Xm), cell productivity (Px), nitrogen-to-cell conversion factor (YX/N), and biomass composition (total lipids and proteins) were selected as responses and evaluated by analysis of variance. The source of CO2 did not exert any significant statistical influence on these responses, which means that the flue gas from ethanol fermentation could successfully be used as a carbon source as well as to control the medium pH, thus contributing to reduce the greenhouse effect. The results taken as a whole demonstrated that the best combination of responses mean values (Xm=4.543gL−1; Px=0.460gL−1d−1; YX/N=15.6gg−1; total lipids=8.39%; total proteins=18.7%) was obtained using as nitrogen source a mixture of 25% NaNO3 and 75% (NH4)2SO4, both expressed as nitrogen.