Harvesting of Spirulina platensis by cellular flotation and growth stage determination

Aim: To investigate an effective harvesting method for Spirulina platensis. Methods and Results: Eighty per cent of S. platensis cells in the logarithmic growth phase were harvested by flotation when the cells were set in a static condition for 2 h. The optimum harvesting time was about day 6 of cultivation. The flotation activity of S. platensis cells was enhanced by the addition of NaCl. Conclusions: The harvesting of S. platensis by flotation is a cost‐effective and straightforward method that can retain the algal quality. The optimum harvesting time of S. platensis can be predicted by the cellular protein to carbon ratio. Significance and Impact of the Study: Flotation harvesting is also applicable to other cyanobacteria with gas vesicles.