Pulsing ultrasound waves could someday remove microplastics from waterways

Colorful particles of plastic drift along under the surface of most waterways, from headwater streams to the Arctic Ocean. These barely visible microplastics—less than 5 mm wide—are potentially harmful to aquatic animals and plants, as well as humans. So, researchers are devising ways to remove them and to stop them at their source. Today, a team reports a two-stage device made with steel tubes and pulsing sound waves that removes most of the plastic particles from real water samples.