The dispersal of microplastics during washing cycles is one of the main threats to marine and ocean ecosystems. To tackle the problem at its source — that is, starting with the washing machine — a group of researchers from German universities and institutions has developed an experimental filter — not yet patented — inspired by the digestive system of certain fish, capable of retaining 99 per cent of microplastics.

The problem, in brief

As highlighted by the latest report from the Changing Markets Foundation, synthetic fibres account for 69 per cent of all textile fibres we wear. The undisputed king is polyester, at 59 per cent. A large share of these materials ends up in the sea. According to the United Nations Environment Programme, or UNEP, between 16 and 35 per cent of the microplastics polluting water globally come from the washing of synthetic garments. And as recent research has shown, there is no significant difference between virgin fibres and recycled synthetic fibres — the latter can in fact generate even more pollutants during washing than the former. For Europeans, this means releasing around 13,000 tonnes of microplastics per year into domestic drainpipes, equivalent to roughly 25 grams per person. https://culturaeconsapevolezza.mase.gov.it/news/plastic-free-anche-nella-moda-microplastiche-e-rifiuti-tessili

The bio-based filter

The German researchers, affiliated with the University of Bonn and the Fraunhofer Institute for Environmental, Safety and Energy Technology (Umsicht) in Oberhausen, and funded by the Federal Ministry for Research, Technology and Space (Bmftr) and the European Research Council (Erc), based their prototype on fish such as mackerel, sardines and anchovies. These animals swim with their mouths open to feed, filtering water through a complex system of gill arches fitted with comb-like structures. In practice, they create an extremely fine mesh that filters and releases water while retaining plankton, which enters the oesophagus, is swallowed and then digested.

The researchers therefore recreated in the laboratory a system similar to the gill-arch funnel, testing various dimensions and also running computer simulations. The material collected by the filter would be compressed, and it would then be possible to dispose of it through separate waste collection after just a few washes. According to the research team, putting the device into production should not be overly expensive, not least because it involves no complex moving parts. The Transfer Center enaCom at the University of Bonn will provide support for the protection and commercialisation of the filter, in collaboration with PROvendis GmbH, a service provider for the university network of North Rhine-Westphalia.