Cleaning up microplastics with sound

The device works on pollutants as small as 10 micrometres in diameter

Spotted: Humans can no longer avoid consuming microplastics. The pollutants are found in almost every aspect of food supply chains, from farmland to fish and single-use plastic bottles. The World Economic Forum (WEF) is calling on the international community to set legally binding measures because while macroplastic pollution has already caught global attention, microplastics are still lagging behind in terms of regulatory and corporate action. 

So far, filtering techniques have proven time-consuming and costly, with the devices often getting clogged with other materials such as sand and debris. Management of the filters frequently requires manual cleaning and removal of the larger items. Professor Yoshitake Akiyama and Professor Hiroshi Moriwaki led a team of researchers in the Faculty of Textile Science and Technology at Shinshu University in using sound to clean microplastics from water. 

The device uses microfluidity, combined with acoustic focusing, to gather microplastics that range in size from 10 to 200 micrometres in diameter. Ultrasonic waves push the microplastics to the centre of a stream of fluid where the pollutants can be collected, although the very smallest microplastics, those that measure five micrometres in diameter, proved to be too small to control with the sound waves.

In tests, 70 to 90 per cent of the microplastics in the fluid were collected, and the scientists believe that a pre-filtration process that removes the biggest pieces could help maintain efficiency of the device. Commercial applications of the device would focus on preventing microplastics from entering the world’s waterways. This could be accomplished by attaching the device almost anywhere that emits wastewater, from washing machines and industrial filtration systems to office and home sewer systems.  

Other ways that Springwise has spotted innovators preventing microplastic pollution include dissolvable make-up wipes and a method for upcycling microplastics from washing machines.

Written By: Keely Khoury