Phototheque VEOLIA

Salmon raised in recycled water

Posted on 08 November 2016.

In western Norway, Veolia has developed a semi-closed circuit fish farming system. It’s a solution that limits aquaculture’s environmental impact and improves productivity.

World salmon farming leader, the Norwegian group Marine Harvest entrusted Krüger Kaldnes, a Veolia subsidiary, with the design and construction of three units producing smolt, the young salmon ready to be moved to sea water. They were installed on the Steinsvik site in 2014.

With a total treatment capacity of around 17,000 m3 of water per hour, these three units can recycle and reuse up to 99% of the water required for rearing juvenile salmon.

Steinsvik is just one example of infrastructure where Veolia is deploying advanced technologies to limit the environmental impact of the aquaculture industry. As Marine Harvest highlights, aquaculture - second largest sector in terms of revenues for Norway behind hydrocarbons (oil and gas) - faces numerous challenges, including environmental ones.

And the solution devised by Veolia to help meet these challenges? Recycling the water used for raising the fish. Krüger Kaldnes developed a particularly effective RAS (recirculating aquaculture system) which, after a series of purification treatments, involves reusing a certain amount of water to supply the fish cages. It is semi-closed circuit fish farming.

The system, used in Steinsvik and elsewhere combines various proprietary technologies including an MBBR (Moving Bed Biofilm Reactor) and Hydrotech drum filters, which eliminate the particles and the carbon and nitrogen pollution produced by the fish.

The system, known as "Kaldnes® RAS", offers better resource management (reduction in water consumption and in pollution) and improves aquaculture productivity – in particular by reducing alevin mortality and promoting growth as a result of better water quality control.

Today, the Steinsvik site is among the largest and most modern of its kind, providing an annual production of 5.3 million smolts, only using between 250 and 500 liters of water per kilogram of fish produced.

Far from stopping there, Veolia has built an even larger facility, again in Norway, capable of producing between 7 and 8 million smolts using recycled water.