Biomass and lipid production from Chlorella vulgaris UTEX 26 cultivated in 2 m³ raceway ponds under semicontinuous mode during the spring season

A Chlorella vulgaris UTEX 26 semicontinuous culture was implemented in 2000 L raceways with M medium during spring season at greenhouse conditions. Areal biomass productivities between 20 and 26 g m⁻² d⁻¹ were reached on the third day. The maximal areal lipid productivity obtained was 6.1 g m⁻² d⁻¹ and an increment in the saturated fatty acids (SFA) proportion (C14–C18) was favored in comparison with the fatty acids obtained with M medium in photobioreactors of 1 L and photoperiod light:darkness 12:12 h. After the eighth day of the culture or biomass concentrations above 0.25 g L⁻¹, the microalgal cultures were prone to contamination by ciliates and amoebae, due to the sugars excreted by C. vulgaris UTEX 26. The periodical addition of NH₄HCO₃ to the microalgal culture maintained the ammonium concentration between 25 and 50 mg L⁻¹, which contributed to diminish the contamination risks by protozoa.