Researchers may have found an effective and sustainable solution to remove microplastics, fragments of less than 5 mm in length, from water. By adding tannins — a natural substance present throughout the plant kingdom, from roots to fruits — to a layer of wood dust, they created a filter that traps virtually all microplastics in water.

Microplastics result from the breakdown of consumer products and industrial waste. They are the most prevalent type of marine debris and can be harmful to the ocean. There’s no technology now available that can rapidly and universally capture them. But researchers at the University of British Columbia may be on to something.

“Most solutions proposed so far are costly or difficult to scale up. We’re proposing a solution that could potentially be scaled down for home use or scaled up for municipal treatment systems,” Orlando Rojas, study author, said in a news release. “Our filter doesn’t contribute to further pollution as it uses renewable and biodegradable materials.”

A solution to microplastics

The new device, called bioCap, works with wood residues, such as sawdust, along with natural polyphenols. To create it, the researchers used sawdust as a substrate through which they filtered water. Then, they modified the sawdust by adding tannic acid, a naturally occurring plant polyphenol.

The only thing left was to put it all to the test. The researchers released various types of microplastics through a water column with bioCap. It trapped from 95.2% to as much as 99% of plastic particles, depending on the type of polymer. They also fed mice bioCap-filtered water and found it prevented the buildup of microplastics in their organs.

“There are microfibres from clothing, microbeads from cleansers and soaps, and foams and pellets from utensils, containers and packaging. By taking advantage of the different molecular interactions around tannic acids, our bioCap solution was able to remove virtually all of these different microplastic types,” Rojas said in a news release.

Rojas and his team highlight that bioCap could be a sustainable, cost-effective and simple strategy to tackle microplastic pollution, a growing global problem. Microplastics have been found in human blood and lungs and in farm animals. They are truly everywhere, from the waters of Antarctica to the cold snow on the top of Everest.

While new developments like bioCap can make a difference, we also need to significantly reduce the amount of plastic we use – especially single-use plastics. Many countries and cities have already taken the first steps, banning products such as straws and crockery, and the United Nations is now discussing a global treaty on plastics.

The study was published in the journal Advanced Materials.