Development of large-scale and economic pH control system for outdoor cultivation of microalgae Haematococcus pluvialis using industrial flue gas.

The aim of this study was to develop the economic and effective buffer system for microalgae mass cultivation using industrial flue gas. Due to the continuous flue gas supplement, culture media acidified, therefore cell growth inhibited. Although buffering agent was added, this result increase in cost for overall culture process. Therefore combined buffer system of bicarbonate and phosphate (BP) for large-scale use was investigated. The bicarbonate buffer system generated from CO dissolution, additionally phosphate buffer system improves the buffer performance under the continuous CO supplementation from flue gas. The microalgae Haematococcus pluvialis was cultivated under autotrophic outdoor conditions using these buffer solutions. As a result, the autotrophic BP buffer system enhanced the biomass and astaxanthin productivity of H. pluvialis to 105% and 103%, respectively. The results confirm that the BP buffer system reduces the cost of microalgal CO conversion process, particularly for the outdoor mass cultivation.