Seaweed enterprise makes profitable use of fish farm waste

Danish seaweed technology is nourishing a new business proposition for land-based aquaculture.

A plug-and-play system for seaweed cultivation gives land-based fish farms an outstanding opportunity to transform problematic nutrient emissions into a new source of income.

Danish start-up company Pure Algae has developed the technology for industrial facilities that use recirculating aquaculture systems (RAS), which enable large-scale fish production in an almost closed loop.

Although modern filtration systems remove as much as 90% of nutrients from RAS fish tanks, the remaining 10% are still an environmental liability and a limiting factor for farms with ambitions to expand. It is this challenge that the Pure Algae’s automated seaweed-growing containers are designed to solve.

High-quality seaweed and tonnes of fish
Founder and CEO Esben Christiansen explains how the scalable, plug-in containers turn the concept of water purification around. From being an expense, nutrient removal becomes a driver of profit.

The technology can turn 60 tonnes of RAS process water into 300 tonnes of high-quality seaweed

“Compliance with environmental regulations is easier because the seaweed consumes waste nutrients in the water. RAS facilities can then produce tonnes more fish while creating an additional revenue stream.”

A rich source of bioactive compounds
Compared to a conventional nutrient capture and storage system, nutrients such as nitrogen and CO2 are captured and utilised for seaweed growth. The seaweed can be sold for use in dietary supplements, food products and cosmetics. Rich in protein, vitamins, minerals and omega-3 fatty acids, seaweed is also an efficient source of nutrition in fish feed – completing the circular loop.

“There are more than 10,000 seaweed varieties, each with their own properties. An important part of our role is to advise aquaculture companies on the best seaweed variety for their facility. Due to the high interest in seaweed from various industries, we can often connect them with a potential buyer for the seaweed that they can deliver with a stable high quality all year round,” Christiansen says.

International exports underway
Pure Algae delivers lab-scale units for production trials and large-scale container systems, which can be installed individually or in clusters. Industrial units for higher capacity needs will be launched in the near future.

The technology is attracting considerable international attention, with exports of the first container systems to Germany, Portugal and Switzerland.