Performance of purifying anaerobic fermentation slurry using microalgae in response to various LED light wavelengths and intensities

BACKGROUND: Anaerobic fermentation slurry (AFS) is a type of high-pollution load wastewater that can cause water eutrophication and algal blooms. The current study focused on the response of microalgae nutrient removal efficiency to various light-emitting diode light wavelengths and intensities. RESULTS: Themicroalgae Chlorella vulgaris was able to remove nutrients from AFS effectively. Furthermore, only moderate light intensities (800, 1300, 1800, and 2300 mu mol m(-2) s(-1)) were required to culture C. vulgaris and induce nutrient removal. Exposure to higher light intensities produced greater dry weight (DW) biomass and achieved higher nutrient removal efficiencies. The order of light wavelengths based on the DW biomass yield of C. vulgaris was red > white > yellow > blue. The order of light wavelengths, according to the nutrient removal efficiencies reached by C. vulgaris, was red > white > yellow > blue. Red light was also the light wavelength with the best economic efficiency for nutrient removal. CONCLUSION: In this study, red light was used as the optimum light wavelength. Furthermore, the optimum light intensity range was from 1300 to 1800 mu mol m(-2) s(-1) when both nutrient removal and economic efficiencies were considered. Moreover, the optimum treatment time was determined to be 120 h. (C) 2012 Society of Chemical Industry