How can process water from freshwater aquaculture be put to productive use? In a video produced by the Finnish Environment Institute (Syke), researchers demonstrate the cultivation of the diatom Phaeodactylum tricornutum using process water from a freshwater recirculating aquaculture system (RAS). The work forms part of SAFE’s research into circular approaches for European freshwater aquaculture.

Filmed at Syke’s Marine Research Laboratory, the video brings viewers into the laboratory where the cultivation work is carried out. The algal biomass produced through this process is intended for use in fish feed being developed and tested within the SAFE project.

Connecting process water with feed development

Recirculating aquaculture systems treat and reuse water within fish production. Even in these systems, process-water streams still need to be managed. SAFE is examining whether some of these streams can be used as inputs for other biological processes rather than being viewed only as outputs from production.

Cultivating microalgae in RAS process water may provide a way to use available nutrients while producing biomass with potential value as a feed ingredient. In the Syke demonstration, these two parts of the circular pathway are brought together: process water from freshwater RAS is used in algal cultivation, and the resulting biomass enters SAFE’s feed-development and testing work.

A practical view of technology development

The video makes the research process visible. It shows the technology at a laboratory-demonstration stage and helps aquaculture stakeholders, researchers and feed specialists see how the concept is being tested in practice. This matters because technology readiness is built through more than a promising idea: cultivation performance, biomass quality and safety, feed performance, process efficiency and scalability all require evidence.

The demonstration is therefore a practical step in the development pathway, not the end point. Continued testing within SAFE will help assess where algal cultivation in RAS process water can contribute to more resource-efficient freshwater aquaculture.

Watch the video

Watch Algal cultivation in RAS process water (SAFE project) and learn more about SAFE’s circular-economy research at projectsafe.eu.

Funding acknowledgement: The SAFE project has received funding from the European Union’s Horizon Europe programme under grant agreement No. 101084549.