What this work is about, in plain words
What is the best way to grow microalgae: in batches, with constant flow, or by periodically replacing part of the culture? The authors compared these methods on spirulina and the green alga Tetraselmis.
The yield of microalgae depends not only on light, nutrients and the species itself, but also on how the process is organized. A culture can be grown as a batch and harvested completely. Or part of it can be withdrawn and fresh medium added — continuously or in portions. The authors compared which of these methods gives the highest productivity.
The experiments were carried out on two cultures from the institute's collection: the cyanobacterium Spirulina platensis and the green flagellate alga Tetraselmis viridis. Both were grown by several methods with all other conditions equal.
According to the authors, the best method was one in which the flow of medium is switched on and adjusted as the culture grows (the "non-proportional flow" method). For both cultures, it gave 1.5 times more biomass than replacing part of the culture in portions at equal intervals, and also more than batch growth.
The work helps choose a cultivation regime when it is important to get more biomass from the same installation.
Limitations. The comparison was made under laboratory conditions on two species. The quality of the biomass and the costs of the different regimes were not compared in the article.