Mass cultivation of Dunaliella salina in a flat plate photobioreactor and its effective harvesting

Abstract

Mass cultivation of Dunaliella salina was standardized in a flat plate photobioreactor followed by a vertical flat plate photobioreactor. Maximum biomass productivity (14.95 ± 0.43 mgL −1 d −1 dry cell weight) was achieved in the latter at inoculum concentration of OD 680nm = 0.1, 100 µmolm −2 s −1 light illumination and 1.0 L min −1 aeration. Semicontinuous operation with varying KNO 3 and NaHCO 3 concentrations resulted highest biomass productivity (17.85 ± 0.55 mgL −1 d −1 ) at 0.50 mM NaHCO 3 and 15 mM KNO 3 . However, maximum lipid (16.36 ± 1.18% dry cell weight) was achieved at 0.75 mM NaHCO 3 and 10 mM KNO 3 . Flocculation studies employing potash alum, FeCl 3 ·6H 2 O or pH showed harvesting efficiencies exceeding 90% in 0.75 mM potash alum or FeCl 3 ·6H 2 O or pH 11, but they yielded low concentration factor (<5) and were detrimental (Fv/Fm < 0.50). A combination of 0.50 mM FeCl 3 ·6H 2 O and pH 9 was found as most suitable flocculating strategy with maximum concentration factor (>14) and least damaging (Fv/Fm > 0.54). © 2018 Elsevier Ltd