Conversion of NaHCO₃ to Na₂CO₃ with a growth of Arthrospira platensis cells in 660 m² raceway ponds with a CO₂ bicarbonation absorber

Abstract

Summary The weight ratio of Na2CO3/NaHCO3 was investigated in order to improve microalgal productivity in large‐scale industrial operations by converting NaHCO3 to Na2CO3 with a growth of Arthrospira platensis cells in 660 m2 raceway ponds. Two microalgal cultivation systems with a NaHCO3 by‐product (SPBP) and a CO2 bicarbonation absorber (CBAP) were firstly thoroughly introduced. There was a 13.3% decrease in the initial weight ratio of Na2CO3/NaHCO3 resulting in a 25.3% increase in the biomass growth rate with CBAP, compared to that of SPBP. Increased sunlight intensity, solution temperature and pH all resulted in both a higher HCO3- absorbance and CO32- release, thereby increasing the weight ratio of Na2CO3/NaHCO3 during the growth of A. platensis. The biomass growth rate was peaked at 39.9 g m−2 day−1 when the weight ratio of Na2CO3/NaHCO3 was 3.7. Correspondingly, the cell pigments (chlorophyll a and carotenoid) and trichome size (helix pitch and trichome length) reached to a maximum state of 8.47 mg l−1, 762 μg l−1, 57 and 613 μm under the CBAP system.