Comparison of nutrient removal from wastewater and lipid accumulation with Aphanizomenonflos-aquae and Microcystis aeruginosa

Two typical water-bloom microalgae, Aphanizomenon flos-aquae and Microcystis aeruginosa, were investigated for their potential of nutrient removal and biofuel production. The algae were cultured in artificial wastewater containing NH₄⁺-N 7.5 mg/L and PO₄^3--P 1.0 mg/L under different light intensity and temperatures. Concentrations of nitrogen and phosphorus were analyzed regularly during algal growth and neutral lipid contens in algae cells was also measured with nile red fluorescent method. It was found that both algae showed high removal rate of PO₄^3--P, which could reach up to 98%. The removal rate of nitrogen was lower, which was less than 52%. Both of A. flos-aquae and M. aeruginosa showed high potential for neutral lipid accumulation. Adjustment of light intensity and temperature could promote the lipid accumulation in algae cells. 12 000 lx was the optimum light intensity for lipid accumulation. A. flos-aquae had higher growth rate and better lipid accumulation ability at 18~22℃. But M. aeruginosa adapted to higher temperatures (22~26℃).