Scientists at the University of Bonn have created a patent-pending filter that removes over 99 percent of microplastics from washing machine wastewater. Inspired by the gill systems of filter-feeding fish, the device prevents clogging and could be integrated into future laundry machines. This innovation addresses a key source of environmental pollution from textile fibers.
Washing machines contribute significantly to microplastic pollution, with a typical four-person household generating up to 500 grams of these particles annually from worn clothing fibers. Much of this material enters sewage sludge, which is often used as fertilizer on fields, spreading the tiny plastics further. To combat this, researchers at the University of Bonn, led by Dr. Leandra Hamann and Dr. Alexander Blanke, have developed a bio-inspired filter modeled on the gill arch systems of fish such as mackerel, sardines, and anchovies.
These fish evolved efficient filtration over millions of years, using a funnel-shaped structure widest at the mouth and narrowing toward the gullet. The walls feature branchial arches with comb-like structures covered in tiny teeth, forming a mesh that captures particles while allowing water to flow through. "During food intake, the water flows through the permeable funnel wall, is filtered, and the particle-free water is then released back into the environment via the gills," Blanke explains. Larger particles roll toward the gullet instead of clogging the mesh, mimicking cross-flow filtration.
The team's filter replicates this design, optimizing mesh sizes and funnel angles through lab tests and simulations. "We have thus found a combination of parameters that enable our filter to separate more than 99 percent of the microplastics out of the water but not become blocked," says Hamann. Without complex moving parts, it promises low production costs. Captured fibers collect at the outlet, are suctioned away periodically, and can be pressed into pellets for disposal every few dozen washes.
Existing filters often clog quickly or fail to capture particles adequately, Hamann notes: "The filter systems available so far, however, have various disadvantages." The University of Bonn and Fraunhofer Institute UMSICHT have patented the invention in Germany, with EU-wide protection underway. Funded by the Federal Ministry of Research, Technology and Space and the European Research Council, the device could reduce textile microplastic release, amid growing concerns over their presence in human breast milk, placenta, and even brains.
