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

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.