The project, named "Seaweed-based cost-effective management for land-based fish farm emissions," aims to scale up a modular system called VALUEFARM. This system combines water purification and the production of sea lettuce, which can help reduce the discharge of nitrogen (N), phosphorus (P), and CO2, while also creating new revenue streams for the fish farming sector. The project is funded through the Eurostars program and runs for 32 months.

The problem with aquaculture

While aquaculture meets an increasing part of the world's demand for fish, it also poses challenges in the form of significant environmental impacts. Nutrients such as nitrogen and phosphorus are often discharged into surrounding ecosystems, causing pollution and oxygen depletion. Niels Holst, senior researcher at Aarhus University and one of the key figures behind SEAWEED4IMRAS, explains:

"The goal of the project is to create a circular economy where waste products from fish farming are reused for seaweed production. The seaweed absorbs nutrients from the water, resulting in cleaner process water and valuable biomass."

The solution: VALUEFARM

The VALUEFARM system is designed to combine advanced biotechnology with practical application. The system consists of eight or more vertical photobioreactors equipped with efficient LED lights and automated sensors. These components enable stable and highly efficient seaweed production regardless of season and weather conditions.

The system will be tested in collaboration with the Kattegatcenter in Grenaa, where it will demonstrate how it can be integrated into land-based fish farming. According to Esben Rimi Christiansen, CEO and founder of Pure Algae, who has been a central driving force in the development, the potential is enormous:

"We can treat large amounts of process water while creating a new sustainable revenue stream. The seaweed we produce is already approved as food and can become an important resource in the diet of the future."

How it works

Esben Rimi Christiansen explains that the system works in several stages to ensure optimal functionality. First, the process water from the fish farm is led through the vertical photobioreactors, where the seaweed plants absorb CO2 from the fish's exhalation as well as nutrients such as nitrogen and phosphorus, also excreted by the fish. The reactors are equipped with LED lights that ensure the seaweed plants can grow efficiently regardless of season or light conditions. Automatic monitoring of pH value, temperature, and light levels ensures that growth conditions are always optimal.

"One of the great advantages is that the system is designed to be modular and flexible. This means it can be adapted to different fish farms and their specific needs," he explains. The seaweed is harvested continuously and can either be sold as food or used for other purposes such as feed or even in the pharmaceutical industry, further increasing the system's sustainability and economic value.

Aarhus University's role in the project

Niels Holst plays a central role in the SEAWEED4IMRAS project, responsible for developing mathematical models to optimize the system's function. He explains:

"My task is to develop and implement a growth model for seaweed that can simulate how different environmental conditions affect production. The model will be used as decision support for both researchers and producers, ensuring that the system operates efficiently and sustainably under various conditions."

This model will also help predict how changes in light, temperature, and nutrient levels affect seaweed growth, making it possible to fine-tune the system to achieve optimal results.

Project goals

SEAWEED4IMRAS aims to:

• Reduce nutrient and greenhouse gas emissions from fish farming.
• Optimize production conditions for seaweed.
• Create a sustainable business model that allows fish farmers to increase production without harming the environment.

By using seaweed as both an environmental and commercial resource, the project addresses some of the most pressing challenges in aquaculture.

Broader perspectives

In addition to the immediate benefits of reducing pollution and creating new products, SEAWEED4IMRAS has the potential to revolutionize the way we think about sustainable agriculture and aquaculture. With the prospect of treating up to 1120 m³ of process water weekly and producing 83,200 kg of seaweed annually, the system could be a game-changer.

The project supports the UN's Sustainable Development Goals for responsible consumption and production, climate action, and life below water. Niels Holst concludes:

"SEAWEED4IMRAS shows how research and innovation can make a real difference. It's about creating technologies that are good for both the environment and society while increasing our global competitiveness."

More information

Contact Senior researcher Niels Holst, Department of Agroecology, Aarhus University. Tel.: 22283340 or mail: niels.holst@agro.au.dk