Biomass and lipid production from Nannochloropsis oculata growth in raceway ponds operated in sequential batch mode under greenhouse conditions

The effect of sequential batch cultures of the marine microalgae Nannochloropsis oculata on lipid and biomass production was studied in 200-L raceway ponds for 167 days (nine harvesting cycles) during winter and spring seasons under greenhouse conditions. The highest biomass concentration and productivity were 1.2 g/L and 49.8 mg/L/day on days 73 (5th cycle) and 167 (9th cycle), respectively. The overall interval of lipid production was between 131 and 530 mg/L. Despite the daily and seasonal variations of light irradiance (0–1099 μmol photon/m² s), greenhouse temperature (2.1–50.7 °C), and culture temperature (12.5–31.4 °C), ANOVA analysis showed no statistical difference (p value > 0.01) on the fatty acid methyl ester (FAMES) composition over the nine harvesting cycles evaluated. The most abundant FAMES were palmitic (C16:0), stearic (C18:0) and palmitoleic (C16:1∆9) acids with 37.1, 28.6, and 8.4 %, respectively. The sequential batch cultures of N. oculata in raceway ponds showed an increasing biomass production in each new cycle while keeping the quality of the fatty acid mixture under daily and seasonal variations of light irradiance and temperature.