A theoretical model of selective cell harvesting and recycling resulting in dominance of the slower-growing over the faster-growing species. (Source: Benemann et al. 1978.)

Figure III. A.2. Initial experiment demonstrating the maintenance of Oscillatoria in outdoor ponds.

Maintenance of a culture of Napa Oscillatoria using selective recycle. Bars indicate the relative volume, concentration and filament length distribution of Oscillatoria (white bar height indicates filaments shorter than 150 pm; vertical stripes indicate filaments between 150 and 375 pm; slashes indicate filaments longer than 375 pm). Volumes of single algal cells were calculated on an equivalent concentration basis and are shown as triangles (shaded area, top). Vertical arrows marked R indicate when the culture was harvested with a microstrainer (30-pm opening fabric) and the captured algae (almost all Oscillatoria) returned to the pond. Experiments were carried out in a 3-m2 circular pond mixed continuously at 3 cm/s. Settled raw sewage, supplemented with 100 ppm of bicarbonate was used as substrate. (Source: Benemann et al. 1977).