Optimization of Algal Biomass Production, Nutrient Removal and Lipid Accumulation in Different Photobioreactors

In this study, open-pond and internally illuminated photobioreactor (PBR) cultivation systems were examined to optimize the algal biomass and lipid production. PBR systems were found to have more effective performance on biomass production, nutrient removal, and lipid productivity than open-pond systems. The effect of cultivation methods (i.e., red, blue, and white LED PBR and open-pond system) on the cell biomass and lipid productivity was also evaluated. Most of the nitrogen and phosphorus were successfully removed in the white LED PBR on Day 3. The maximum and average dry biomass productivity rates for the white LED PBR were 1.27 g/L/day and 0.81 g/L/day, respectively, which were 56.8%-234% and 62%-170% higher than those for the other treatments. Among the cultivation systems, 1.16-1.85 times and 3-6 times of lipid content and lipid production rate, respectively, were observed in the white LED PBR. White LED PBR performed best in nutrient removal, biomass production, lipid content and productivity, followed by the blue LED PBR, open-pond system and red LED PBR. The performance of PBRs internally illuminated with different LED colours was then evaluated and optimized for simultaneous biomass production and wastewater treatment using Chlorella vulgaris. More than 95% removal of nitrate and phosphate could be achieved on Day 3 in all PBRs installed with white LEDs, and the highest dry cell weight of Chlorella vulgaris was obtained in PBR with 12 white LED bars.