The Potential of Microalgae Cultivation in Multiple Stages

Microalgae cultivation in reused medium can reduce the cost of producing bioproducts and enable lower consumption of water, energy and nutrients. This work gathers the main information about the cultivation of these microorganisms in reused medium over the last 20 years. It uses analysis of patent filings and publications of scientific articles on the main microalgae species used and strategies for medium reuse. Asia produced the highest number of patent filings, with China being the largest provider. Private sector companies are responsible for the largest number of patents filed. The genus Chlorella has been the most studied when it comes to the reuse of medium for the cultivation of microalgae, and this strategy has been applied mainly in crops that use the standard medium for biomass production, and also for crops in wastewater in a smaller number of cases. It was found that the reuse of medium allows multiple cultivation stages/cycles with biomass production in concentrations that can reach values higher than those obtained in fresh medium. However, it may be necessary to employ strategies to reduce the contamination and lack of nutrients of the residual medium.