| Abstract: | A tubular photobioreactor for outdoor cultivation of Spirulina platensis was successfully operated for the last two years. The reactor was made of transparent 2.4‐cm diameter tubes with a total length of approximately 101‐m and a volume of 124‐liter. Flow was induced using an airlift pumping system. To optimize the system further, a larger tube diameter was also tested. Preliminary results have suggested that a larger tube diameter might provide increased output with reduced surface area requirements. Results of experiments comparing the productivity of the same culture volume in tubes of 2.4 cm and 5.0 cm will be presented which show a small decrease in productivity by volume, but a large increase in areal productivity. This suggests that the larger tube diameter would be an appropriate choice for larger scale systems. Additionally, data will be presented demonstrating the effectiveness of an on‐line surface scatter turbidimeter for accurate measurement of Spirulina density when correlated to manual dry weight measurements. |
