Enhanced carbon dioxide fixation of Haematococcus pluvialis using sequential operating system in tubular photobioreactors

• Sequential operating system was applied to evaluate the CO2 fixation efficiency.
• Haematococcus pluvialis and flue gas were used in microalgae cultivation.
• We identified aspects of cell growth, dissolved carbon in liquid and vented gas.
• The fixation efficiency increased more than 3-fold compared to simple operation.

Carbon dioxide sequestration by microalgae photosynthesis is an attractive alternative to mitigate climate change due to greenhouse gas emission. In our study, Haematococcus pluvialis and a sequential operating system were exploited to examine the carbon dioxide fixation efficiency in a tubular photobioreactor. We investigated the carbon balance over the photobioreactor, including the carbon bound in the biomass, dissolved inorganic carbon in the liquid media, and gaseous carbon remained in the headspace and vented out from the photobioreactor. The experiments were performed both indoors and outdoors, using air-mixed 3% CO2 gas and the flue gas from power plant. As a result, the sequential operation system using H. pluvialis cultivation improved the carbon dioxide fixation efficiencies from 12.34% to 49.37% (indoor), and from 13.55% to 49.15% (outdoor), respectively, compared to single bioreactor operation mode. This sequential operating system would be useful for enhanced conversion of carbon dioxide from flue gas by microalgae photosynthesis.