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Sterner helps Hima Seafood turn fish sludge into fertilizer

October 27, 2023  By  Nestor Arellano

(Image: Sterner)

Hima Seafood’s land-based fish farm in Rjukan, Norway is touted as the world’s largest recirculating aquaculture system facility for growing trout. The aquaculture company is keen on sustainability and has recently turned to water treatment solutions company Sterner Group AS to purify the sludge produced by the Rjukan facility.

The facility was designed to produce 9,000 tons of trout annually. A key element of Hima Seafood’s vision to produce premium trout in the most sustainable way possible is the treatment of sludge produce by the facility.

RAS facilities produce a substantial amount of sludge.


For example, Norway’s salmon and rainbow trout biomass production for 2017 was 1.3 million tons with a corresponding sludge volume of 2.1 million tons. By 2050 Norway’s sludge volume is predicted to reach 11 million tons.

“Traditionally, such sludge has been considered waste, but technological advancements in recent years have opened the door to a more sustainable management,” said Karl Levinsen, project manager at Eyvi. Eyvi is the main contractor working with Total Betong on the RAS project.

In RAS facilities, the sludge need to be separated from the water before the water can be circulated back into the system.

The sludge treament system developed by Sterner, processes the sludge while maintaining its nutrient value. Sterner’s technology ensures dewatering and drying of the sludge removed from the fish farm, resulting in a high-quality product that can be reused as organic fertilizer in agriculture.

“The end product is a natural green fertilizer,” the company said.

“This will have significant value, not only for Hima Seafood but also for promoting the circular economy and protecting our environment,” according to Levinsen.

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