Algae Could Be the Answer to Cleaning Water Polluted With Chemicals

Excess algae in streams, rivers and lakes is often considered a consequence pollution. In Europe alone, more than half of the bodies of water are heavily polluted, and researchers found over 500 chemicals in the continent’s rivers that stem from industry and agriculture. Soon, algae could be associated with cleaning up these polluted waters instead. 

Researchers at the University of Duisburg-Essen in Germany developed a water purification process using the fossilized remains of a common type of algae called diatoms. These microscopic single-celled organisms live in water and have shells made of silica, a material already used in water purification. Because of their porous structure, diatoms can absorb a wide variety of pollutants, said Anzhela Galstyan, an author of the study and junior professor of chemistry at the university.

“Diatoms are primary producers in aquatic systems, converting carbon dioxide into energy through photosynthesis. They are among nature’s most significant carbon dioxide capturers,” Galstyan told TriplePundit. “We are interested in diatoms because the remains of these algae accumulate on the ocean floor, making them readily available and easy to collect. However, we are now working on cultivating them in the lab to develop a circular technology for sustainable use.”

The process of modifying the fossilized algae shells to be more absorbent starts with chemically cleaning residue from their surfaces. Next, the diatom remains are chemically modified to improve their ability to capture specific pollutants. 

“This approach proved highly effective,” Galstyan said. “Building on this success, we are now exploring modifications to capture specific metal ions, such as those found in wastewater from the mining industry, where toxic metals are prevalent.”

Scientists have studied algae’s potential for water purification since the early 20th century. It is considered a cost-effective and energy-efficient alternative to other common treatment methods. Despite promising developments, its adoption in the water industry is slow. 

Galstyan and her team tested the algae shells on two pollutants from the textile industry commonly found in rivers and groundwater called methylene blue and methyl orange. 

“As a starting point, we focused on these pollutants, but we anticipate capturing other contaminants as well, particularly those posing risks from the pharmaceutical industry,” Galstyan said. “This is an important area, and our next project will specifically address organic risks from pharmaceutical waste, for example.”

The researchers also tested the shells under various conditions in the lab, such as water that is more or less salty and more or less acidic. Regardless of the conditions, the algae consistently and effectively removed pollutants. It removed 100 percent of the methylene blue in the span of an hour and about 70 percent of the methyl orange.

Algae are also a renewable resource and can be cultivated using less energy than other common water filter materials, like activated carbon. “Algae is widely available in nature and can even be cultivated in wastewater,”  Galstyan said. 

The shells the researchers are working with can also be recycled. The team washed them with a solvent to remove the pollutant, and after five cycles, they still functioned well, she said. 

“Our focus is on tailoring these modifications for different applications while ensuring the chemical processes remain simple, energy-efficient and free from toxic solvents,” Galstyan said. 

Looking ahead, Galstyan and her team aim to refine and optimize the process and find ways to use the residue removed from the shells in the first step of the process. She believes the materials they create could be integrated into existing water purification systems without requiring a complete overhaul. 

“This technology focuses on replacing materials with more cost-effective and environmentally friendly alternatives,” Galstyan said. “I hope that within five to 10 years, we can at least partially replace expensive existing systems with bio-based solutions.”