Development of gas recycling photobioreactor system for microalgal carbon dioxide fixation

A gas recycling photobioreactor was developed to achieve high CO2 conversion, in which Chlorella vulgaris was cultivated under various light intensities. The light intensity affected the algal growth and the CO2 concentration in the exit gas. However, the final cell density was independent of light intensity and was limited by nitrate concentration in the medium. In the linear growth phase, the CO2 concentration in the exit gas ranged 4.6 to 6.0 % (v/v) when 20 % (v/v) CO2 balanced with 80 % (v/v) N-2 was introduced into the photobioreactor. The gas recycling photobioreactor developed in this work was claimed to be a useful system for microalgal CO2 fixation.