They purify water – and what would otherwise be pollution is turned into biodiesel, or raw materials for pharmaceuticals i.e., biochemicals. NMBU researcher Suvidha Gupta uses algae to create value from wastewater.
"Our findings could revolutionize wastewater treatment. We transform wastewater into a valuable resource while reducing pollution," says Gupta. She researches what tiny algae – microalgae – can do with wastewater from a dairy.
"When producing dairy products, the dairy also generates large amounts of wastewater. This can be harmful to the environment if not properly treated," she explains.
"Superheroes"
The focus is on wastewater – the water used to clean production facilities. When machines and floors are washed, the water carries away milk residues and other remnants of production.
"We grow microalgae in this water. These tiny organisms are like superheroes: they can consume all the harmful substances and help us purify water naturally. At the same time, they grow and produce valuable sugars, fats, and proteins," Gupta says.
In scientific terms, this is called biomass – material derived from living plants or microorganisms.
Threads and clumps
Microalgae are very efficient at purifying water, but collecting the algae afterward is a challenge. Suvidha Gupta compares it to gathering dust from the air on a windy day. Her solution is to combine two algae species. One type is microalgae that grow in the water and purify it. The other type also purifies wastewater, and in addition it forms long, thin threads. These threads capture the small algae. Together, the two algae species form clumps that become heavy enough to sink to the bottom of the water.
"This process allows us to purify the water and produce valuable biomass without using expensive equipment or energy. We don’t need chemicals, large amounts of electricity, or heat, yet we can harvest the microalgae and turn them into green fuel and valuable products," she explains.
The biomass can also be converted into biodiesel and bio-chemicals that can serve as raw materials for pharmaceuticals.
Created a multi-enzyme magnetic nanocatalyst
The researchers face another challenge: they need effective methods to extract valuable substances from the algae.
"We need to break open the algae to access the beneficial components inside, like sugars. These microalgae have very thick cell walls. You can compare them to the shell of a coconut, making it hard to access these ingredients," Gupta explains.
She has developed a completely new tool: a multi-enzyme magnetic nanocatalyst. She describes it as functioning like molecular scissors that break down the tough cell walls of the algae, releasing sugars and fats. Since the nanocatalyst is attached to magnetic particles, it can be pulled out using a magnet. Additionally, it can be reused multiple times and remains effective for at least the first five uses.
Waste becomes a resource
Once extracted, the sugars feed bacteria, which convert them into valuable chemicals, while fats are transformed into biodiesel. While these processes have been known for a long time, the method of transforming pollutants into raw materials is new.
The quantities are small – it takes two liters of wastewater to extract one gram of microalgae. However, the water becomes clean enough to be released directly into nature, and 55% of the microalgae consist of sugars.
These figures come from Dr Gupta’s work at the Reaction Engineering and Catalysis laboratory at the Norwegian University of Life Sciences (NMBU) in Ås. In a real dairy, the composition of the wastewater varies from place to place and day to day.
"But above all, we have demonstrated that this is feasible," says Suvidha Gupta.
"What we see as waste can become a valuable resource that creates cleaner water and greener energy," she concludes.
Facts about the research
The research project AlgalBB aims to develop a cost-effective process to use microalgae to purify wastewater from dairies, then convert the algae into biofuels and valuable chemicals.
Wastewater from the dairy sector is challenging and expensive to treat. Without treatment, it is harmful to the environment. Current biological treatment methods are energy-intensive, they often produce sludge that requires additional management and disposal, increasing environmental and economic challenges.
AlgalBB is conducted at NMBU's Faculty of Science and Technology and is funded by the EU Horizon Europe program.
Algae are organisms that perform photosynthesis, like plants, and live in moist environments. Microalgae are so small that individual algae can only be seen under a microscope.