Ceramic membranes as a potential high-performance alternative to microplastic filters for household washing machines

The development of effective, commercially available microplastic filters has become more important due to the steady increase in microplastic emissions from laundry washing cycles and the stringent regulations enforced in many countries. In this present study, commercially available microplastic filters and alternative membranes were thoroughly investigated with real laundry wastewater based on their microplastic filterability and organic contaminant retention. The microplastic filterability of each filter and membrane was assessed using a fluid imaging microscopy device, known as FlowCam, which is recognized for its rapid and realistic quantification. As a result, commercially available microplastic filters revealed a poor microplastic filtering performance, with a removal efficiency of only 19.7–24.8%, with no retention of organic contaminants. A subsequent systematic comparison of polymeric and ceramic membranes with smaller pores was thus conducted to explore their potential as effective alternative microplastic filters for household washing machines. While both membranes effectively retained microplastic fibers and organic contaminants, the ceramic membrane exhibited lower susceptibly to fouling due to its relatively hydrophobic surface. Additionally, it also removed a significant proportion of hydrophobic compounds from real laundry wastewater, thereby improving its organic retention. Further research into the convenient cleaning, long-term sustainability, and practical design of mountable ceramic membranes is necessary before their widespread adoption as external washing machine filters.