Influence of light quality on Chlorella growth, photosynthetic pigments and high-valued products accumulation in coastal saline-alkali leachate

Abstract

Using saline-alkali leachate to cultivate microalgae is an effective way to realize the utilization of wastewater and alleviate the shortage of water resources. Light source is usually used as an optimized parameter to further improve the cultivation efficiency of microalgae. In this work, the influence of light qualities on the growth and high-valued substances accumulation of Chlorella sp. HQ in coastal saline-alkali leachate were investigated. The specific growth rate of Chlorella in coastal saline-alkali leachate was 0.27–0.60 d−1. At the end of cultivation, the algal density under blue light reached 8.71 ± 0.15 × 107 cells·mL−1, which was significantly higher than the other light groups. The lipid content in the biomass was 29.31–62.95%, and the highest lipid content and TAGs content were obtained under red light and blue-white mixed light, respectively. Percentages of total chlorophylls (0.81–1.70%) and carotenoids (0.08–0.25%) were obtained in the final biomass of the coastal saline-alkali leachate. In addition, the contents of photosynthetic pigments and three high-valued products under mixed light were higher than those of monochromatic light, and the protein, total sugar and starch content under blue-red mixed light was 1.52–3.76 times, 1.54–3.68 times and 1.06–3.35 times of monochromatic blue light and red light, respectively. HIGHLIGHTS Chlorella in coastal saline-alkali leachate exhibited better growth curve under blue light.; The highest total lipid content per unit biomass of Chlorella was obtained under red light.; Mixed LEDs light can improve the photosynthetic ability of Chlorella in coastal saline-alkali leachate.; High-valued substances content of Chlorella under mixed LEDs light was higher than that of monochromatic light.;

Keywords

• chlorella
• high-valued products
• light quality
• pigments
• saline-alkali leachate