Acousweep: A Microplastic Fibre Separation System Using Sweeping Acoustic Waves

Microplastics, tiny plastic pieces or particles smaller than 5mm in diameter, are one of the major pollutants in oceans. In 2020, a report by the United Nations Environment Programme suggested that plastics make up about 60% of all clothing material. When washed or worn, microplastics are shed from clothes, and annually, approximately 9% of microplastics released to the ocean come from clothes and textiles.

Separating and Collecting Microplastic Fibres using Sweeping Acoustic Waves

To alleviate microplastic pollution generated from clothes and textiles, HKRITA has developed Acousweep, a separation system to capture microplastic fibres in water by using acoustic manipulation techniques. The system consists of a chamber with a transducer inside that generates sweeping acoustic waves to form standing waves. The standing waves then transfer the trapped microplastic fibres to the reflector on the other side. When the concentration of microplastic fibres is sufficiently high, the sensory system opens a needle valve to let the microplastic fibres drip into a collection tank for further treatment.

Acousweep is a more efficient and eco-alternative to collect microplastics. The current practice uses membrane-type filters to capture such microplastics. Microplastic fibres can block the pores of the filters, resulting in lowering its efficiency and therefore requiring regular replacement. Acousweep, on the other hand, is filter-free and its processing rate is not compromised by the need to reset and replace membrane-type filters, thus achieving continuous water treatment.

An Award-winning Project Heading for Industrial Upscale

In 2022, Acousweep was awarded a Silver Medal in the Special Edition Inventions Geneva Evaluation Days for its ground-breaking approach of using sweeping acoustic waves to separate microplastic fibres in water systems. The lab scale system is able to upgrade the treatment capacity from 100 litres to 5-10 tonnes of water per hour. The system can be installed in a container for easy transportation and then installed in existing sewage outlets in plants. In addition to treating wastewater generated from the textiles and apparel industries, the Acousweep can also be applied to other industry sectors for microplastic collection. In the long-term, the system creates a sustainable marine ecosystem through improving the quality of oceanic waters.

Acousweep is an environmentally friendly approach compared to the current treatment of microplastics

Microplastic fibres agglomerate and form a large mass that can be easily dealt with in future treatment

Acousweep receives a Silver Medal in the Special Edition Inventions Geneva Evaluation Days 2022

Project video