Food processing typically generates a lot of wastewater, which needs to be cleaned before it is discharged into local waterways. According to new research, however, this water could first be used as a very effective fertilizer for cultivated algae.
In a study by scientists from Sweden’s University of Gothenburg and Chalmers University of Technology, “process water” was collected from four sources: a salmon farm, a factory that processed herring, another that processed shellfish and – as a vegan option – an oat milk maker.
This nitrogen and phosphorus rich water was then added for the water used to grow four different varieties of sea lettuce, in an onshore seaweed farm.
After just eight days, all types of treatment water were found to significantly increase the growth rate and protein content of all varieties of sea lettuce – on average, algae grew over 60% faster and their protein content quadrupled. It is important to note that the use of the treatment water did not affect the taste of the plants.
And while the sea lettuce is Consumed as a food in its own right, its increased protein content could also allow it to serve as an additional source of protein in other foods, much like soy does today. According to scientists, the protein content of boosted sea lettuce is over 30%, compared to about 40% in soybeans.
It is hoped that once further research has been conducted, a win-win scenario can result. On the one hand, algae farms would be able to produce much more of a higher value product. On the other hand, food processing companies could actually to sell their process water to these farms, instead of having to clean it. It’s even possible that in a circular arrangement, farmed fish could be raised on food made from algae grown using their farms’ wastewater as fertilizer.
“We think you could have terrestrial cultures of algae, like sea lettuce, near a herring plant, for example,” said lead scientist Kristoffer Stedt, a doctoral student in the University’s Department of Marine Science. from Gothenburg. “Growing algae can clean a lot of nutrients from process water. It brings us closer to a sustainable approach, and companies have another leg to stand on.
An article about the study was recently published in the journal Algae research.
Source: University of Gothenburg