The effects of illumination factors on the growth and HCO3− fixation of microalgae in an experiment culture system

Illumination factors can affect growth of microalgae and HCO3− fixation. In order to optimize microalgae growth in culture system and HCO3− fixation from wastewater, the effects of light source, light interval on the growth of microalgae, Chlorella sp. and Scenedesmus obliquus sp., were studied in experiment culture system. The effects of light intensity and available illumination area on HCO3− fixation of microalgae were also considered. Microalgae were grown in a constant light incubator-shaking table experiment system (CLIST system) to assess biomass, pH, DO, and HCO3− concentration at 30 °C cultivation temperature. The light interval evaluated were 15 min, 1 h, 4 h, 8 h and 12 h, respectively. HCO3− fixation of microalgae was investigated at five different light intensities (1000, 2000, 3700, 6800 and 8200 lux) and four available illumination areas (45, 80, 120, 200 cm2) in CLIST system. Under the light interval of 12:12, light intensity of 6800 lux and available illumination area of 200 cm2, the removal rate of HCO3− in the water was found to be 65.7%, with a maximum biomass concentration above 1400 mg/L. In this study, 0.953 g HCO3− in per litre of wastewater would be captured by microalgae, in other word, producing 1.00 g of microalgae biomass fixed 1.10 g of HCO3−.