Researchers use waste water to add protein to seaweed

Growing seaweed in food process wastewater increases its protein – saving water while producing more nutritious food

Spotted: There has been a growing awareness of the amount of water used in agriculture – and the impact this has on water scarcity. However, a huge amount of water is also used in food production. In fact, in the US, processing and packaging, distribution and marketing, and household use account for around 37 to 50 per cent of water use. Now, researchers at the University of Gothenburg and Chalmers University of Technology have developed techniques for using process water from the food industry as fertiliser in seaweed cultivation.

The researchers started with the knowledge that algae grown in the vicinity of fish farms grow better and have a higher nutritional content due to the presence of fish faeces. These faeces contain high levels of nutrients such as nitrogen and phosphorus, which aid in algal growth. The research team then conducted trials to determine if using process water from food production, which contains similarly high levels of these nutrients, would aid seaweed growth.

The team tested different types of seaweed, adding process water from the herring industry, salmon farming, shellfish processors, and oat milk manufacture to each. After allowing the seaweed to grow for eight days, they analysed the results. They found that in all cases the use of process water raised the protein content in the seaweed from around 10 per cent to more than 30 per cent – within striking distance of the protein content of soybeans (around 40 per cent).

Kristoffer Stedt, a University of Gothenburg doctoral student who worked on the project pointed out that growing seaweed in this way could create a more circular approach to the production of food protein. “We think that you could have land-based cultivations of algae, such as sea lettuce, near a herring factory, for example. Seaweed cultivation can cleanse large portions of the nutrients from the process water. That brings us closer to a sustainable approach, and the companies have another leg to stand on,” says Stedt.

Efficient, biodegradable and requiring no land to grow, seaweed is being developed for a host of uses. Some innovations recently spotted by Springwise include food packaging with an edible seaweed coating, and vegan shrimp made from seaweed.