Today, the site is a leading example of an industrial circular economy. Close collaboration with local industries, farmers and the municipality has developed into what is known as an industrial symbiosis centre.
鈥楾he idea is simple: to make use of residual products from the fish industry and create new value locally. The organic residual streams are used to produce biogas and biofertiliser. The biogas is used to generate heat and electricity for nearby industries. At the same time, nutrients from the biofertiliser are returned to agriculture,鈥� explains Claes Lundberg, one of the founders of Rena Hav.
There was a risk that the industries
would have to relocate听
Fifteen years ago, the area was dominated by three large fish-processing companies: Ler枚y, Marenor, then Domstein, and Orkla, then Abba. The industry grew beyond the capacity of the existing wastewater treatment system. In addition, large quantities of sludge and fish waste were transported to biogas plants a long way away in Norway and Denmark, resulting in CO鈧� emissions.
鈥楾here was a risk that the industries would have to relocate,鈥� says Claes Lundberg.
The biogas plant was built with a high capacity from the outset. One important principle has been that fish waste cannot be stored for too long, as this causes odour problems and increases costs. Instead, the operation has developed a system in which resources are processed quickly and returned to the cycle.
The biogas is not yet upgraded to biomethane for use as vehicle fuel. Instead, it is piped directly to neighbouring industries or to generators. In this way, it can be used to provide heating and cooling as well as to generate electricity. Biogas production can be adjusted in response to electricity prices, creating opportunities to supply power when demand on the electricity grid is at its highest.
Emissions drastically reduced
Wastewater treatment has been a crucial part of the initiative. Investments in technology and the recruitment of experienced process wastewater treatment specialists have reduced discharges of oxygen-depleting substances into the sea by around 99 per cent, from approximately 160 tonnes per year. Nitrogen emissions have also been reduced in stages, from 12.6 tonnes to less than four tonnes per year.
Nutrients that were previously lost are now used as fertiliser in agriculture.
鈥榃e have continuously learnt more about our wastewater treatment process. Initially, we had some problems controlling the biology of the process and experienced some foaming. But for several years now, we have managed it systematically and have seen a good rate of improvement.鈥�
The nutrient-rich residual products also became the basis for the company鈥檚 own fertiliser. Its effects became apparent when a farmer accidentally created clearly defined comparison plots in a field following problems with the GPS system. Differences in the height and colour of the crops could be seen after just a few days.
鈥楾his led to the product later being tested by homeowners and hobby growers as well. According to users, the fertiliser produced very good results. We now have our own fertiliser brand.鈥�
Salmon was the next step
Over time, the company began considering how the residual streams could be put to even better use. If the material could be turned into energy and fertiliser, why not food? This marked the beginning of its investment in land-based salmon farming.
鈥楾he advantages are considerable. In a closed system, you can control water quality, collect nutrients and reduce the occurrence of problems such as salmon lice, which are a major issue in marine fish farming. At the same time, phosphorus and other resources that might otherwise be lost can be captured and recycled,鈥� says Claes Lundberg.
The lengthy permitting processes have at times been frustrating, but according to the company, they have also provided time to refine the technology and study the health and growth of the fish.
Being built in stages
鈥楢s a result, instead of buying ready-made solutions, we are now developing our own system based on what we have learnt from our own test facility. We have now been raising healthy fish there for a long period, which has been verified by researchers from the University of Gothenburg.鈥�
The plan is to expand the land-based salmon farm in stages, initially to an annual production of around 2,000 tonnes and subsequently to around 4,000 tonnes. The expansion will be complemented by a slaughter facility and increased handling of organic residual streams at Rena Hav鈥檚 biogas plant.
鈥楾his circular system has been developed in collaboration with neighbouring companies, the agricultural sector and Soten盲s Municipality, as well as the University of Gothenburg. And not least Link枚ping University, which has contributed expertise and knowledge in industrial collaboration and the circular economy.鈥�
The same principle runs through the entire initiative: turning waste into a resource. Biogas, wastewater treatment, fertiliser, fish feed and salmon production together form parts of a circular system in which energy, nutrients and raw materials are recovered and used as resource-efficiently as possible before leaving the system.
鈥楾he aim is to create both economic and environmental value by making the most efficient possible use of local resources,鈥� says Claes Lundberg.
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