This Fish-Inspired Filter Could Keep Tons of Plastic From Leaving Your Washing Machine

How anchovies inspired a breakthrough filter that traps nearly all microplastics from washing machines.

Every load of laundry sends tiny plastic fibers down the drain. These fragments, shed from synthetic fabrics, slip through most wastewater filters and spread through rivers, farmland, and food.

But researchers at the University of Bonn think they’ve found a practical way to stop them by adapting a filtering trick that fish have used for millions of years.

Way of the Anchovy

Anchovies, sardines, and mackerel are masters of aquatic filtration. They feed by swimming with their mouths open, funneling water through a comb of arches lined with tiny teeth known as denticles. These denticles let water pass but catch plankton, sweeping the tiny organisms toward the throat as the fish swims. Scientists call this process semi-cross-flow filtration: instead of hitting a barrier head-on, particles glide along the filter surface before being carried away.

“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,” said biologist Dr. Alexander Blanke, a co-author of the new study. “However, the plankton is too big for this; it is held back by the natural sieve structure. Thanks to the funnel shape, it then rolls toward the gullet, where it is collected until the fish swallows, which empties and cleans the system.”

The system is clever enough to clean itself thanks to an evolutionary trick that has kept these fish feeding efficiently for millions of years. And that self-cleaning mechanism gave Dr. Leandra Hamann, then a biologist at Bonn’s Institute for Organismic Biology, an idea.

Fish-inspired Filter

In their recent paper published in the journal npj Emerging Contaminants, Hamann and her team describe how they mimicked the gill arch system using 3D printing and a simple mesh. The result—a “fish-inspired filter,” or FiF—looks like a cone set inside a pipe. Water enters through the wide end and flows along the mesh at a shallow angle, much like water rushing through a fish’s mouth. Instead of slamming into the filter head-on, the particles roll gently across its surface and gather at the tip.

In tests, the FiF removed up to 99.6% of microplastic fibers from washing machine wastewater. At the same time, it resisted clogging. “We have thus found a combination of parameters that enable our filter to separate more than 99% of the microplastics out of the water but not become blocked,” Hamann said.

The key lies in what the researchers call the “angle of attack.” When the filter mesh sits at about 11 degrees relative to the flow, fibers are less likely to stick and more likely to roll away—just as plankton do in fish. Periodic pulses of water then flush these fibers out into a small outlet chamber, leaving the filter clear for the next cycle.

The whole process repeats automatically, mimicking the way a fish “swallows” to clean its gills.

Elusive Enemy

Microplastics (MPs) are among the most pervasive pollutants on Earth. They drift through the atmosphere, settle on mountain snow, and move up the food chain from plankton to people. Washing machines are a major contributor. A single household can send as much as 500 grams of microplastic fibers into wastewater each year. Even when treatment plants capture most of it, those trapped fibers accumulate in sewage sludge that’s often used as fertilizer, returning the plastic to soil and crops.

RelatedPosts

Ancient haute cuisine — Mesolithic people had caviar feast
Small Somalian cavefish hints at mammals’ nocturnal ancestor
Microplastics are all over the place, even in the sea breeze
Roman fish salting workshops reveal two whale species lost from the Mediterranean

“Intercepting MPs before they reach the sewage system is a critical and underdeveloped intervention point,” the researchers write. The FiF, they argue, offers a practical fix: an inexpensive, low-maintenance filter that could be built directly into washing machines.

Unlike other technologies that rely on dense membranes or complex mechanics, the FiF uses nothing more than flow and geometry. It’s made of standard materials, costs little to produce, and doesn’t need replacement filters. According to Hamann, it could reach homes within a few years. “It is not far from entering commercial use,” she told New Atlas. “If a large filter company would take on those last experiments and design and manufacturing challenges, it could be ready within one or two years.”

Our Reliance on Synthetics

The Bonn team’s work fits into a broader trend in biomimicry, or engineering inspired by living systems. In recent years, manta rays have guided the design of filters whose lobes make particles bounce off instead of sticking. Shark skin patterns have inspired antibacterial surfaces. But few examples are as directly translatable as the FiF.

The researchers are already testing the device with real wastewater that also contains hair, sand, and detergent residues. They plan to add sensors that automatically trigger cleaning when pressure builds up. Eventually, future washing machines could compress the captured fibers into small plastic pellets that homeowners simply throw away.

The FiF won’t stop plastic pollution at its source—our dependence on synthetic fabrics—but it could block one of its busiest escape routes.