Waste heat and sugars from Hallsta pave way for eco-friendly farming of king prawns. It sounds like a joke, but it is absolutely true. 2012 will mark the launch of a prototype king prawn farm on the industrial site around Hallsta Paper Mill.


“We’ve signed an agreement with the mill to use the land and to harness heat from the mill’s process water and residual products from the paper manufacturing,” says Matilda Olstorpe, a microbiology researcher at the Swedish University of Agricultural Sciences (SLU), and MD of the start-up company Vegafish.


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The company is now seeking investment capital for its continued development. The aim is to start full-scale production during 2014, with an initial focus on the Swedish market.

“We also looked into other farming options, but we decided to focus on king prawns. Market surveys show that consumption is rising and that more and more consumers are looking for responsibly farmed king prawns.”


Up on land

King prawns are currently farmed on a large scale in locations such as Southeast Asia, but production causes considerable damage to the mangrove swamps. Things will be different using the Vegafish process in Hallsta, with Vegafish moving its natural system up onto dry land.

The king prawns are farmed in ponds together with tilapia, a tropical whitefish. The water in the ponds is heated – via a heat exchanger – by wastewater from the mill.

“The water circulates in a closed system, so nothing can escape to contaminate the sea,” explains Matilda Olstorpe.

For the prawns to grow, they do of course require food. Matilda has collaborated with other experts such as Anders Kiessling, professor of aquaculture, to develop a microbial feed. This comprises bacteria and yeasts that thrive on the residual sugars in the process water that leaves the mill. The microorganisms also provide the prawns and fish with protection against disease. What is more, the microorganisms break down excrement and convert it into new, protein-rich fish food.


Waste products become a resource

This exciting project to rear king prawns has its origins in the Hallsta Network, whose aim is to develop the area and attract new employment to Hallstavik. It was in this context that the idea arose of trying to put waste heat from the paper mill to good use.

“Relatively quickly, we came to realise that some form of farming would be a good option. Fish was the first suggestion,” relates Hans Hammarfors, who is an active member of the network.

The farming idea resulted in the network applying for and securing EU funding for a feasibility study. It was then that the SLU and king prawns entered the picture. The team behind Vegafish includes former Holmen employees Bengt Mattson and Tage Sundblom, who know all about the mill’s processes. So 10 000 square metres of the mill site will now host a brand new business that will create new jobs in the area. The Vegafish sign is already in place and the company will soon start converting waste products and matter that is not suitable for human consumption into quality food – in this case something that all sushi lovers and general foodies will be able to enjoy.


Read more about the project at www.vegafish.com



TEXT: Anders Thorén

PHOTO: Lasse Modin


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