Outdoor production of Tisochrysis lutea in pilot-scale tubular photobioreactors

In this paper we study the outdoor production of Tisochrysis lutea in pilot-scale tubular photobioreactors (3.0 m3). Experiments were performed modifying the dilution rate and evaluating biomass productivity and quality, in addition to the overall performance of the system. Results confirm that T. lutea can be produced outdoors on a commercial scale in continuous mode, obtaining productivities of up to 20 g m−2 day−1 of biomass, which are rich in proteins (45 % d.wt.) and lipids (25 % d.wt.). The utilization of this type of photobioreactor allows one to control the levels of contamination and pH within the cultures, but daily variations in solar radiation impose elevated dissolved oxygen concentrations and insufficient temperature conditions on the cells inside the reactor. Excessive dissolved oxygen reduces biomass productivity to 68 % of that which is maximal, whereas inadequate temperature reduces it to 63 % of maximum. Thus, by optimally controlling these parameters, biomass productivity can be almost doubled. These results confirm the potential for producing this valuable strain on a commercial scale in optimally designed/operated tubular photobioreactors as a viable biotechnological industry.