Scientists in Germany have created a new filter that can remove more than 99% of microplastics from washing machine wastewater, offering a promising way to reduce one of the largest sources of plastic pollution.
The invention, developed at the University of Bonn and now patent-pending, was inspired by the way fish naturally filter food from water using their gill structures.
The results were published in npj Emerging Contaminants.
Washing machines shed large amounts of plastic fibers every year—up to 500 grams for a typical four-person household.
These fibers come from clothing, especially synthetic fabrics, and are one of the main contributors to microplastic pollution.
After leaving the washing machine, the fibers enter wastewater treatment plants and become trapped in sewage sludge, which is often later used as fertilizer.
This means microplastics eventually make their way into agricultural soils and can later spread to food, water, and even the human body.
Existing filters for washing machines have not solved the problem. Many clog quickly or fail to trap enough particles to be effective. Dr. Leandra Hamann and her colleagues wanted to find a better approach, so they looked to nature for inspiration.
Many fish species—such as mackerel, sardines, and anchovies—feed by filtering tiny organisms from water as they swim. They do this using a sophisticated structure inside their mouths called the gill arch system.
The team studied this system closely. In filter-feeding fish, the gill arches form a funnel that is wide at the mouth and narrow toward the throat.
As water flows through this funnel, plankton gets caught on a natural mesh formed by comb-like structures covered in small teeth. Instead of clogging, the trapped material rolls down toward the throat, where the fish swallows it. This design keeps the filter clean and extremely efficient.
Using this principle, the researchers built a similar funnel-shaped filter for washing machines.
They experimented with different mesh sizes and funnel shapes until they found a design that removed more than 99% of microplastics without becoming blocked. Both real-world tests and computer simulations confirmed the filter’s performance.
Unlike complex mechanical systems, the new filter uses no moving parts and should be inexpensive to manufacture. The captured microplastics accumulate in a small outlet area, where they are automatically suctioned away several times per minute.
These collected fibers could then be compressed into a small plastic pellet that users can remove every few dozen washes and throw away safely with household waste.
The team has already applied for German and EU patents and hopes washing machine manufacturers will incorporate the filter into future models. Reducing microplastic pollution has become increasingly urgent, as recent studies show microplastics in human breast milk, placentas, and even brain tissue.
By borrowing one of nature’s most elegant filtration designs, the new fish-inspired filter offers an effective and practical solution to a growing environmental and health concern.
