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

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 OD680nm = 0.1, 100 mu molm(-2)s(-1) light illumination and 1.0 L min(-1) aeration. Semicontinuous operation with varying KNO3 and NaHCO3 concentrations resulted highest biomass productivity (17.85 +/- 0.55 mgL(-1)d(-1)) at 0.50 mM NaHCO3 and 15 mM KNO3. However, maximum lipid (16.36 +/- 1.18% dry cell weight) was achieved at 0.75 mM NaHCO3 and 10 mM KNO3. Flocculation studies employing potash alum, FeCl3 center dot 6H(2)O or pH showed harvesting efficiencies exceeding 90% in 0.75 mM potash alum or FeCl3 center dot 6H(2)O or pH 11, but they yielded low concentration factor (< 5) and were detrimental (Fv/Fm < 0.50). A combination of 0.50mM FeCl3 center dot 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).