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Keywords:

  • microalgae;
  • Nannochloropsis gaditana;
  • nitrogen source;
  • lipid;
  • biodiesel

To effectively cultivate microalgae it is necessary to understand nutrient requirements to maximize productivity while minimizing cost. One issue associated with large scale systems is optimizing the amount and form of nitrogen; hence the effects of nitrate and urea on microalgae growth, lipid yield, and fatty acids profile for microalgae Nannochloropsis gaditana were investigated. In addition, the effects of high concentrations of urea and nitrate, similar to what may be found in agricultural run-off, were studied. As others have demonstrated, the lipid yield decreases when there is excess nitrate in the medium. Replacing the nitrate with urea has a more significant negative effect on lipid productivity; however, combinations of urea and nitrate are more optimal indicating that agricultural wastewater may be a realistic nitrogen source. The lipid profile is not significantly different if nitrate or urea is the nitrogen source and the major fatty acids are palmitic acid (C16:0) and palmitoleic acid (C16:1), which are readily converted to biodiesel. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 551–555, 2014