Screening and application of Chlorella strains on biosequestration of the power plant exhaust gas evolutions of biomass growth and accumulation of toxic agents

To use microalgae for the biosequestration of carbon dioxide (CO) emitted from the coal-fired power plants, the screening of high CO tolerant microalgae and their accumulation of toxic agents have attracted significant research attention. This study evaluated 10 Chlorella strains for high CO tolerance using combined growth rates and growth periods subjected to logistic parameters. We selected LAMB 31 with high r (0.89 ± 0.10 day), high k (6.51 ± 0.19), and medium Tp (5.17 ± 0.15 day) as a candidate for CO biosequestration. Correspondingly, six genes involving carbon fixation and metabolism processes were upregulated in LAMB 31 under high CO conditions, verifying its high CO tolerant ability. LAMB 31 cultures exposed to exhaust gas of power plant under different flow rates grew well, but the high flow rate (0.6 L/h) showed inhibition effects compared with low flow rates (0.2 and 0.3 L/h) at the end of the culturing period. The toxic agents in the exhaust gas including sulfur, arsenic, and mercury accumulated in LAMB 31 biomass but were deemed safe for use in the production of both human food and animal feed based on the National Food Safety Standard in China. This study showed a complete process involving high CO tolerant microalgae screening, high CO tolerant verification, and in situ application in a power plant. Data results provide valuable information as the basis for future research studies in microalgae application on CO mitigation at emission sources.