Conversion of NaHCO (3) to Na(2) CO (3) with a growth of Arthrospira platensis cells in 660 m(2) raceway ponds with a CO (2) bicarbonation absorber

The weight ratio of Na(2) CO (3)/NaHCO (3) was investigated in order to improve microalgal productivity in large‐scale industrial operations by converting NaHCO (3) to Na(2) CO (3) with a growth of Arthrospira platensis cells in 660 m(2) raceway ponds. Two microalgal cultivation systems with a NaHCO (3) by‐product (SPBP) and a CO (2) bicarbonation absorber (CBAP) were firstly thoroughly introduced. There was a 13.3% decrease in the initial weight ratio of Na(2) CO (3)/NaHCO (3) 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 [Formula: see text] absorbance and [Formula: see text] release, thereby increasing the weight ratio of Na(2) CO (3)/NaHCO (3) 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 Na(2) CO (3)/NaHCO (3) 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.