Modern recirculating aquaculture systems for fish production have a water demand of less than 1% of the system volume. Dissolved and particulate nutrients can be efficiently separated from the water and used in following recycling systems. A worthwhile opportunity is the integration of photoautotrophic methods to regain dissolved nutrients by the generation of additional biomass. The production of microalgae in photo-bioreactors is technically compatible with the fish production in recirculating aquaculture systems. First tests were promising, but must now be turned into a reliable operation.
Generally, microalgae boast a higher yield per surface area than agriculture. With their high surface/volume ratio, microalgae are particularly well-suited for effective nutrient uptake.
The integration of photobioreactors does not only mean, that biological processes are part of process engineering, but also that periodic processes, such as the intake of carbon dioxide and nitrate by microalgae, have to be integrated. That will be achieved by numerical modeling and the implementation of algorithms in the process of automatization.