Effect of Different Light Sources on Algal Biomass and Lipid Production in Internal Leds-Illuminated Photobioreactor

Abstract

Illumination and nutrients are key factors to the biomass and biodiesel production from microalgae. In this study, the effects of various light wavelengths, light intensities and cultivation medium on the growth and lipid content of Chlorella vulgaris were investigated by using LEDs (Light Emitting Diodes) with different wavelengths in an Internal LEDs-Illuminated Photobioreactor. C. vulgaris was grown for 10 days under 18:6 h Light/Dark cycles with different light colors (cool white, blue and red) and intensities (50, 70, 90 and 110 μmol m-2s-1). The effects of the illuminations were investigated for different light intensity at 25°C culture temperature. The maximum dry biomass of 1353.33 mg/L was observed at cool white light of 110 μmol m-2s-1 during the 7th culture day, with the highest overall dry biomass production (117.23 mg/Ld-1) within cultivation time. The highest lipid content (34.06 %) was obtained with the blue color due to light efficiency and deep penetration. Moreover, the highest lipid productivity (31.86 mg/L d-1) was observed in 50 μmol m-2s-1 with cool white lights. The lipid productivity was further optimized by increasing the light intensity of cool white light. The highest lipid productivity was observed at 110 μmol m-2s-1 light intensity of 658.99 mg/L during the 10th culture day. To conclude, the result of our study shows that C. vulgaris cultivated with wastewater in photobioreactors is efficient in producing algal biomass and removing nitrogen and phosphorus nutrient in wastewater sewage.