Effects of Light on the Removal of 4-Chlorophenol by Chlorella vulgaris

Light condition is one of the most important factors affecting the removal efficiency of 4-chlorophenol (4-CP) from water by microalgae. In the present study, the growth of Chlorella vulgaris and removal of 4-CP by C. vulgaris were investigated with difference light-to-darks ratio, light intensities and light sources. The results showed that the resistance of C. vulgaris to 4-CP was enhanced with light-to-dark ratio and light intensity increasing. The biomass of C. vulgaris with constant light (0.985 g/L) and 72 μmol m−2 s−1 light intensity (0.928 g/L) exposed to 30 mg/L 4-CP stress was highest. The biomass of C. vulgaris was higher under blue light (0.881 g/L) than that under green (0.720 g/L) and red light (0.748 g/L). Meanwhile, the highest removal rate of 4-CP by C. vulgaris was achieved under 72 μmol m−2 s−1 light intensity with blue light as light source. Constant light, 72 μmol m−2 s−1 light intensity and blue light corresponded to 4-CP removal rates of 88.6, 82.0 and 59.1%, respectively. This work demonstrated that light conditions profoundly impacted the performance of C. vulgaris to 4-CP removal.