Nutrients, Water, and Carbon Dioxide for Growth

Microalgae use phosphorus in metabolic processes like energy conversion and photosynthesis (Zhu et al., 2013). Like nitrogen, some forms are more easily absorbed than others, with the most easily absorbed form as orthophosphate. Phosphorus must be added to the culture in excess of the stoichiometric requirement because not all of it will be bioavailable (Chisti, 2007). However, if the concentration is too high, growth is inhibited (Zhu etal., 2013). 

Microalgae use carbon dioxide (CO ) during photosynthesis (Schenk et al., 2008). To prevent an uptake limitation, CO must be supplied in sufficient amounts, O.lSkPa in the case of photobioreactors (Schenk et al., 2008). For cultivation, approximately 1.83 g of CO is required per gram of microalgae produced (Chisti, 2007). The gas can also be used to regulate pH in the culture. Sources for CO include an air- and CO -enriched mixture or flue gas. 

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