Producing salad with water emitted from salmon farming

Columbi Salmon, NIBIO, Morefish, and BioMar, have conducted a study which concludes that there is great potential in growing plants in the same system as fish. The innovation supports the UN sustainability goals and Columbi Salmon seeks to realise this system of food production on a larger scale.

Salmon farming in recirculation aqua systems (RAS) provides the opportunity to produce a large amount of food with small amounts of water. The production emits fish sludge and water used in the production process, which can be used in other valuable forms of production. The concept involves a co-production of plants and aquatic animals, while aquatic organisms contribute to full resource utilisation.

– We aim to make onshore salmon production more sustainable, through better resource utilisation. The experiment indicates that salmon production can become carbon neutral since the plants are binding up carbon from fish production, through both water and air, says CEO Anders Hagen in Columbi Salmon.

The experiment was performed with 1,000 salmon, and by cultivating the salad type «Partition». The production was executed in fresh water, as many plants are sensitive to salt, according to project manager Mari Båtnes Birkeland of Columbi Salmon.

– We will eventually carry this out on a larger scale. Hence, the satisfying results in this experiment was important to us, says Birkeland.

– Encouraging results

The project was located and performed at NIBIO Landvik's aquaponic plant in Grimstad from December 2020 to May 2021.

– The salad that was grown in the aquaponics system had an impressive growth. In line with our hypotheses, we saw very encouraging results. Plant production with RAS means that food production can be multiplied using the same amount of water. In addition, we promote sustainable usage and protection of water and marine resources in support of the UN sustainability goals, says researcher Siv Lene Gangenes Skar at NIBIO.

Water quality, fish welfare, carbon dioxide, and plant quality, are among the factors that were analysed and carefully assessed throughout the trial period. BioMar performed a life cycle assessment (LCA) analysis of the feed given to the plant, and NIBIO performed further measurements of the carbon flow throughout the system. Columbi Salmon’s goal is to become carbon neutral.

– These analyses were compiled into a mass balance that accounts for all that is added and taken out of the system. This process gave useful insights and results, which we will make use of in our future work, says Gangenes Skar.

Will link technologies together

However, scaling up a recirculating aqua system, where fish and plants coexist in the same water, may create conflicting interests between fish and plant production. Furthermore, the process may struggle to be economically sustainable. Therefore, the study investigated how to make feasible this type of food production on a larger scale, without affecting current fish production. The solution involves designing a new production system.

– We want to look at other options to connect new environmental technologies, so that onshore salmon production can become more sustainable in the future. Further utilisation of the resources and opportunities from both forms of production will provide a new approach to a new industry, says Ole Nordal, business developer at Columbi Salmon, and adds:

– The results from this experiment enable us to take the next step towards a full-scale production plant that can grow salad or other vegetables in water stemming from onshore fish farming. This way, we utilise valuable resources that would otherwise be wasted.