Clean water is a human right, but even in highly developed countries, persistent pollutants continue to enter the water cycle — despite modern infrastructure. The main contributors include pesticides, pharmaceutical residues, industrial chemicals, microplastics, dyes and PFAS. According to the German Environment Agency (UBA), by 2023, 40 active pharmaceutical ingredients had already been detected in drinking water alone. Levels are significantly higher in groundwater, surface water and the run-off from wastewater treatment plants. Conventional treatment processes often encounter technical, environmental or financial limitations and are unable to remove all trace substances.
Multifunctional catalyst designs on flow-through foam ceramics for sustainable water treatment
Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS are breaking new ground. They are developing compact foam ceramics with functional coatings that use photocatalytic oxidation to effectively break down even persistent pollutants. “By exposing the functionalized surfaces to UV light, highly reactive radicals are created in the treated water, which decompose organic impurities. This process does not produce any undesirable by-products, nor does it require additional oxidizing agents such as ozone,” says Franziska Saft, a research scientist at Fraunhofer IKTS in Dresden, pointing out the advantages of the development. “Our efficient and sustainable solution mainly focuses on the treatment of industrial process and wastewater.”
The efficiency of this process depends heavily on the contact between the pollutant, the catalyst and light. Thanks to their highly porous, network-like structure, the foam ceramics provide large surfaces, making them ideal carriers for various catalysts and adsorbents. In addition, the high open porosity level of up to 90 percent enables good light transmission.
“Our foam ceramics provide plenty of space for integrating various catalysts. This allows us to create a highly reactive surface area, enabling high catalytic conversions even when only thin layers are applied to the foam ceramic. The catalysts must be stabilized on the foam so they are not rinsed out with the wastewater flow,” adds Daniela Haase, who is also working on the project.
On-site piloting
The researchers and their interdisciplinary project teams are developing the wastewater treatment plants themselves. This includes the whole process from the selection and design of the multifunctional foam ceramics with optimized geometry and catalyst coating to suitable light sources, such as energy-efficient UV LEDs. The reactor design is also specifically tailored to the respective requirements. This approach enables integration into existing systems as well as application-specific scaling and piloting at the customer's premises. Customers include companies from the pharmaceutical, semiconductor, paper, dairy and textile industries that want to break down the pollutants directly on site before they are discharged into wastewater treatment plants. This prevents them from entering the aquatic environment in the first place.
The results so far have been promising. Initial pilot applications have shown that the photocatalytic ceramic foam systems successfully break down pollutants. To further increase their efficiency, the teams are working on innovative catalyst designs and combinations with adsorption materials. In the long term, the researchers aim to further scale the technology and establish it as a key component of modern industrial water cycles. They are thus making an important contribution to protecting the environment and securing high-quality water resources.
Fraunhofer-Gesellschaft
