Abstract
A bench-scale 3-L internally illuminated concentric-tube airlift photobioreactor with an aspect ratio (H/D) ratio of approximately 2.0 and riser-to-downcomer area (Ar/Ad) ratio of 0.42 was designed, fabricated, and tested for the cultivation of Spirulina platensis. Using the results of the bench-scale experiments, a preliminary techno-economic analysis of producing dried Spirulina biomass in a larger scale (in four 20-m3 photobioreactors) was conducted. For this analysis, the aspect ratio and Ar/Ad were maintained. The selling price of the Spirulina powder was based on literature. For the preliminary techno-economic evaluation, 300 days per year production and continuous operation was assumed. Results show that Spirulina powder production plant with a total photobioreactor capacity of 80-m3 revealed an attractive venture. The profit margin is positive, and the payback period is 6.34 years. A sensitivity analysis was also conducted. The effects of total photobioreactor capacity and operating conditions on net income, profit margin, and payback period were determined. The minimum selling price at various total photobioreactor capacities were also calculated.
