Utilization of Model Power Plant Flue Gas for Cultivation of Chlorella vulgaris and Scenedesmusobliquus: Effect of Gaseous Pollutants on Biomass Production and CO2 Biofixation

Power plants are considered a major contributor to carbon dioxide emissions. Moreover, flue gas of power plants contains other compounds such as NOx and SOx that can affect growth rate of microalgae. Therefore, in this study the effect of CO2 in different concentrations of 0.04%, 5% and 15%, NOx in 100ppm and SOx in 60ppm was investigated simultaneously on biomass production and carbon dioxide fixation of two industrially important microalgae, Chlorella vulgaris and Scenedesmus obliquus. At CO2 concentrations of 0.04%, 5% and 15%, the maximum CO2 fixation rate was 0.768, 0.73 and 0.69g/l/d for Chlorella vulgaris and 0.311, 0.53 and 0.212g/l/d for Scenedesmus obliquus, respectively. the results showed that at 15% of CO2, maximum CO2 fixation rate (RCO2) of Chlorella vulgaris was decreased from 0.69 to 0.65g/l/d by adding 100 ppm of NOx to culture medium, also a reduction from 0.69 to 0.212g/l/d was observed when 60 ppm of SOx was injected to CO2 stream. However, In the case of Scendesmus obliquus, an increase in RCO2 from 0.212 to 0.36 and 0.212 to 0.24g/l/d was achieved in the presence of the same amount of NOx and SOx, respectively. At the same culture conditions, Chlorella vulgaris shows higher fixation rate than Scendesmus obliquus. CO2 fixation rate increasing by Scendesmus obliquus in the presence of acidic gases (NOx and SOx) shows that Scendesmus obliquus tends to grow in lower pH.