Scale-Up a Fibonacci-type photobioreactor for the production of Dunaliella salina

Abstract

In this work, the previously proposed Fibonacci-type photobioreactor is scaled up and evaluated to produce Dunaliella salina. First, the composition of the culture medium was optimized to achieve maximal productivity. Next, the Fibonacci-type reactor was scaled up to 1,250 L maintaining high solar radiation interception capacity of this type of reactor. Finally, the performance of the reactor for the production of green cells of Dunaliella salina at the environmental conditions prevailing in the Atacama Desert was evaluated. Data demonstrated that the proposed photobioreactor allows the temperature, pH and dissolved oxygen concentration to be maintained within the optimal ranges recommended for the selected strain. Both better exposure to solar radiation and photonic flow dilution avoids the use of a cooling systems to prevent overheating under outdoor conditions. The system allows up to 60% more solar radiation to be intercepted than does the horizontal surface. Likewise, allowing to maintain the pH efficiently through 100% CO 2 Injection and to keep the dissolved oxygen concentration in acceptable ranges, thanks to its adequate mass transfer capacity. The biomass concentration reached up to 0.964 g·L -1 , three-times higher than that obtained in a raceway reactor under the same environmental conditions, whereas productivity was up to 0.12 g/L·day (2.41 g/m 2 ·day). Maximum specific outdoor growth rates reached up to 0.17 day -1 . Undoubtedly, this technology scaled up constitutes a new type of photobioreactor for use at the industrial scale since it is capable of maximizing biomass productivity under high light conditions.