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A self-cleaning, bio-inspired high retention filter for a major entry path of microplastics

npj Emerging Contaminants 2025
Leandra Hamann, Christian Reuß, Hendrik Herzog, Kristina Schreiber, Christian Geitner, Alexander Blanke

Summary

Researchers designed a washing machine filter inspired by how ram-feeding fish use their gill arches to strain food from water, achieving up to 99.6% retention of microplastic fibers while a built-in self-cleaning mechanism prevents clogging. This bio-inspired filter could significantly reduce the estimated millions of microfibers released into waterways from household laundry each year.

Abstract Microplastic (MP) fibres from washing machines are a major source of environmental pollution, yet, existing domestic filtration solutions are prone to clogging and have limited retention. Inspired by the gill arch system of ram-feeding fishes, we developed a bio-inspired filter that employs semi-cross-flow filtration with a conical filter element geometry, periodic self-cleaning and optimised inflow. Laboratory tests show that the fish-inspired filter (FiF) retains up to 99.6% of MP test fibres. Clogging is reduced by collecting up to 85% of the fibres outside the FiF through a periodic cleaning mechanism. CFD and flow tank experiments demonstrate that filtration performance is strongly influenced by the angle of attack and inlet geometry. The FiF achieves a low concentrate volume (∼5%), increasing yield and minimising post-treatment. Our findings highlight the potential of bio-inspired filtration mechanisms for engineering applications such as washing machines requiring high efficiency and modular design.

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