چكيده به لاتين
Microalgae as phototropic microorganisms play a key role in the production of biofuels (bio-ethanol and biodiesel) with the production of valuable intracellular materials such as starch and lipid. In recent years, the use of microalgae for the treatment of wastewater as well as the production of biofuels has been taken into consideration. In this study, a mixed microalgal culture was used to investigate the effect of medium concentrations of nitrate (0, 400, 800, 1200 and 1600 ppm) and phosphate (0, 20, 40, 60 and 80 ppm) on starch, lipid and intracellular substances of microalgae using response surface methodology. Results showed the highest content of starch (48%) and lipid (40%) based on dry cell weight under nitrogen starvation. In addition, the highest amounts of starch and lipid were observed at initial 60 ppm of phosphate and 400 ppm of nitrate in which nitrate and phosphate were completely removed during 10 days. Results also showed increases of 26% in starch and 44% in total lipid under optimal conditions as compared to the original modified COMBO medium. Additionally, a flat plate photobioreactor was designed and its performance was examined. With this photobioreactor, starch and total lipids increased by 1.90 and 2.03 times, respectively. Our results, therefore, showed that initial nitrate and phosphate concentrations as well as bioreactor type are three important factors affecting starch and total lipid content of microalgal cells, which are applicable on a large scale.
Keywords: Mixed Microalgae, Biofuel, Flat Plate Photobioreactor, Wastewater Treatment
