Nitrogen Removal and Lipid Production from Secondary Wastewater Using Green Alga Chlorella vulgaris

Increasing nitrogen discharges into natural water systems have caused more frequent eutrophication and other water quality issues.Microalgae are fast growing photosynthetic microorganisms that can assimilate nitrogen and phosphorus from water.Also, lipid content of certain strains of microalgae could reach over 60%, making microalgae excellent feedstock for biodiesel production.Green alga Chlorella vulgaris was tested for nitrogen removal and lipids production using secondary wastewater from municipal wastewater treatment plant.Around 60% of NH 3 -Nitrogen was removed after 48 hour, and removal rate was further increased to 75% when carbon dioxide gas was added periodically to control pH.When more active algae seeds were used, NH 3 -Nigrogen removal rate of 97.1% was achieved.Chlorella vulgaris was also very effective for removing low concentration of phosphate from secondary wastewater.When growing at normal conditions, Chlorella vulgaris contained more polar lipid than neutral lipid.Total lipid content of Chlorella vulgaris ranged from 10.6% to 14%, and fatty acids were mainly C16 and C18, making it good biodiesel stock.A freshwater microalgae survey in southwest Ohio was also conducted to provide useful information for future outdoor algae cultivation.24 genera of cyanobacteria and 49 genera of eukaryotic algae were identified, with Synechococcus sp. and Cryptomonas sp.being the predominant prokaryotic and eukaryotic microalgae, respectively.iii