Microplastic pollution purged from contaminated water using ultrasound

Acoustic waves can be used to separate microplastics from contaminated water, and could be a new way to tackle this ubiquitous pollutant. Researchers at the New Mexico Institute of Mining and Technology in the US who carried out the research discussed it at the spring meeting of the American Chemical Society (ACS) on 28 March.

Most plastics in the ocean break down into very small microplastic particles less than 5mm across that can harm aquatic life. Filtration is the most common method of getting microplastics out of water, but the New Mexico Tech team instead decided to come up with a method of concentrating plastic particles in flowing water with sound waves.

A similar approach has been used to separate red blood cells from plasma in the past, for instance. Some researchers have even used it to pull microplastics out of pure water samples prepared in the lab. That previous work, however, involved tiny volumes of water and microplastics that were only tens of micrometres wide.