Productivity and photosynthetic efficiency of outdoor cultures of Tetraselmis suecica in annular columns

In this study, 120-l annular columns were used to cultivate Tetraselmis suecica outdoors. The mass transfer at different aeration rates and the influence of the harvest rate on productivity and biochemical composition were investigated. The potential of the system was evaluated by estimating productivity at full-scale. Two different arrangements to simulate a full-scale plant and determine the "overall areal productivity" (OAP) were experimented with. In August 2003, one experimental column (full-scale column) was placed between seven dummy columns. All the reactors were positioned at a distance of 0.8m wall to wall and centred at the vertices of equilateral triangles. A second experimental column (isolated column) was placed in a separate area under full sunlight. In August 2004, the columns were placed side by side in an east-west oriented row at a distance of 0.24m wall to wall. In the first experiment, the mean volumetric productivity of the full-scale column was not significantly lower than that achieved by the isolated column (0.46 against 0.49g l-1 day-1) in spite of the shading by the dummy units. The average OAP and efficiency of conversion of visible solar radiation (PE) were 36.3g m-2 day-1 and 9.4%, respectively. In the second experiment, the full-scale column attained a mean volumetric productivity of 0.42g l-1 day-1. The OAP and the PE were 38.2g m-2 day-1 and 9.3%, respectively.