Steel sludge transformed into powerful water cleaner for antibiotic pollution

Researchers have developed an innovative way to turn steel industry waste into a low-cost material that can clean antibiotics out of water, offering a promising solution to one of today’s growing environmental challenges.

Steel mills generate large volumes of iron-rich sludge during wastewater treatment. Traditionally, this sludge has been disposed of through landfilling or incineration, raising concerns about waste management and heavy metal contamination. Now, a team led by scientists from Changsha University of Science and Technology has found a way to convert this industrial byproduct into a valuable resource: a special form of biochar that can break down tetracycline, one of the world’s most widely used antibiotics.

Tetracycline is frequently detected in rivers, groundwater, and even drinking water sources due to its heavy use in medicine, livestock, and aquaculture. Persistent antibiotic residues in the environment not only harm aquatic life but also contribute to the spread of antibiotic resistance – a pressing public health concern worldwide.

In the new study, the researchers produced iron-rich biochar by heating steel sludge in an oxygen-limited environment, a simple “one-step pyrolysis” process. When combined with peroxydisulfate – a powerful but stable oxidant – this biochar acted as a catalyst, triggering chemical reactions that generated reactive oxygen species capable of degrading tetracycline.

The team found that biochar produced at 450 °C (called FSB450) was especially effective. Under optimal conditions, it removed more than 85% of tetracycline from water in just two hours. The breakdown occurred through both radical and non-radical chemical pathways, ultimately reducing the antibiotic to smaller, less toxic molecules. Importantly, toxicity tests suggested that the treated water posed lower risks to aquatic organisms such as fish, algae, and daphnia.

Beyond its effectiveness, the iron-rich biochar showed strong magnetic properties, allowing it to be quickly separated from water with a magnet and reused multiple times with only minor performance loss. This feature makes the approach both practical and environmentally safe.

“Our study shows that steel sludge, once considered an industrial waste problem, can be transformed into a powerful tool for water purification,” said lead author Dr. Xunli Bao. “This not only helps tackle antibiotic pollution but also provides a sustainable way to recycle industrial byproducts.”

The research highlights a dual benefit: turning waste into a valuable resource while addressing the urgent need for cost-effective technologies to clean up contaminated water. With further development, this approach could be scaled up for real-world wastewater treatment applications.

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Journal Reference: Bao, X., Zhou, L., Liu, B. et al. Peroxydisulfate activation by one-step pyrolysis iron-rich sludge biochar for tetracycline removal in water: performance, mechanism and degradation pathway. Biochar 7, 87 (2025). https://doi.org/10.1007/s42773-025-00471-1 

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About Biochar

Biochar is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field. 

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