Are we overestimate the contribution of microplastics from industrial laundry? Microplastic exploration in an...

Industrial laundry wastewater has emerged as a significant source of microplastic (MP) pollution, yet limited research has comprehensively investigated its contribution. This study aimed to address this gap by evaluating MP contributions from industrial laundry and examining potential MP removal technologies. We focused on an industrial laundry in Sweden and its downstream wastewater treatment plant (WWTP), introducing two full-scale pilot filtration trials-Drum filtration and Ultrafiltration (UF)-to assess MP control performance. Wastewater samples were collected from the industrial laundry both before and after Drum and UF filtration, along with WWTP sludge samples. MP extraction involved a multi-step process of enzyme digestion, oxidation, and flotation, followed by MP analysis using Focal Plane Array-micro-Fourier Transform Infrared Spectroscopy (FPA-micro-FTIR). Our findings confirmed that industrial laundering can be a major MP source, with polyester and smaller MPs being most prevalent. MP fragments, rather than fibers, were predominant across most samples. Both Drum and UF filters demonstrated high MP removal efficiencies of over 90 % by mass, suggesting that controlling MP source is feasible. However, a mass balance analysis revealed a substantial increase in MP contributions from the local town during both trials, which underscored that local town is another significant source of MPs.