External Microplastic Filters for Washing Machines: Advances, Technical Challenges, and Biofouling Mitigation

Laundry-derived microplastic fibers are major source of environmental microplastic pollution. Because conventional wastewater treatment processes cannot completely remove fibrous microplastics, washing machine-mounted filters have been developed as a promising source-control approach for the reduction in microfiber emissions. This review thus summarizes recent advances in external filtration systems and membrane-based technologies for laundry wastewater treatment. The characteristics of laundry wastewater, microfiber release behavior, and recent regulatory trends are discussed together with the performance of commercially available filtration systems. The applicability of advanced membrane materials, including ceramic membranes, for high-efficiency microfiber separation is also highlighted. Particular attention is given to the microbial contamination and biofouling of microplastic filters, which can affect their filtration efficiency, operational stability, and household hygiene. This review also discusses the potential reuse of captured microplastics for membrane fabrication as a sustainable pathway for waste valorization and circular resource utilization. Finally, current limitations and future perspectives for the development of efficient, hygienic, and sustainable laundry microplastic filtration technologies are discussed.