The ancient evolution of fish mouths could help solve a modern source of plastic pollution.
Inspired by these natural filtration systems, scientists in Germany have invented a way to remove 99 percent of plastic particles from water. It's based on how some fish filter-feed to eat microscopic prey.
The research team has already filed a patent in Germany, and in the future, they hope their creation will help curb a ubiquitous form of plastic pollution that many are unaware of.
Related: There's a Surprisingly Easy Way to Remove Microplastics in Drinking Water
Every time a load of laundry is done, millions of microplastics are washed from the fibers of our clothes into local waterways.
By some estimates, up to 90 percent of plastic in 'sewage sludge' comes from washing machines. This material is then often used in agriculture as soil or fertilizer, possibly exposing those who eat the resulting crops to these pollutants.
At this stage, it is unclear what microplastics are doing to human health when they invade our bones and organs, but some toxicologists are concerned by their initial findings among animals.
Figuring out a way to capture plastic pollutants before they leave our washing machines is challenging work. Current filtration systems available on the market can easily become clogged.
Researchers at the University of Bonn and the Fraunhofer Institute for Environmental, Safety, and Energy Technology turned to nature for inspiration. They decided to make a water filtration system that mimics the mouths of some fish, like mackerel, sardines, and anchovies.
These ocean creatures swim through the water with their mouths open to feed on tiny plankton. Over millions of years, they have evolved comb-like structures inside their mouths that capture microscopic prey.
"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," explains functional morphologist Alexander Blanke from the University of Bonn.
"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 towards the gullet, where it is collected until the fish swallows, which empties and cleans the system."
Based on this anatomy, researchers designed a cone-shaped filtration system, lined with a mesh-like surface area.
Instead of hitting the mesh straight on, like other filtration systems, plastic particles 'roll' along the edge of the new device.
This provides greater surface area for filtering as wastewater is funneled through the device. The plastic particles are then caught outside the filter and flushed into a separate compartment that can be emptied every few dozen washes, like the lint filter in a dryer.
Related: Microplastics Can Spread Dangerous Pathogens, Scientists Warn
Unlike other plastic filtration systems on the market, this one reduces clogging by 85 percent.
Since the 1950s, when synthetic microfibers, such as polyester and nylon, were first mass-produced, at least 5.6 million metric tons of synthetic microfibers have been released from our clothing, according to recent predictions.
While many are now aware of the plastic in their kitchens, our clothes continue to leach pollutants into the environment unabated and often ignored.
Unless we replace the materials in our clothing, high-efficiency plastic filtration systems will be essential for mitigating pollution in the future.
Thankfully, nature is giving us a leg up.
The study was published in npj Emerging Contaminants.