From Source to Sip: Evaluating the Removal of Micro- and Nanoplastics in Conventional Drinking Water Treatment Plants

High Resolution Image Download MS PowerPoint Slide Micro- and nanoplastics (MNPs) are found in drinking water resources, and characterizing their removal during treatment remains a challenge. In this study, we analyzed raw and treated drinking water from four conventional treatment plants that use Lake Erie as their source and differ based on variations in the design of specific unit operations. MNPs down to 0.5 μm were quantified and identified using scanning electron microscopy and optical photothermal infrared spectroscopy. Raw water concentrations were 2–12 million particles/L, resulting in mass concentrations of 1.8–14.5 μg/L. Removal during treatment averaged 54% and 75% for particle and mass concentrations, respectively. Nanoparticles (NPs) accounted for 47–70% of the measured particles in all samples. Interestingly, there was no significant difference in the treated water MNP concentrations, which averaged 2.0 million particles/L, equivalent to an estimated mass concentration of 1.5 μg/L. The most prevalent polymers were polyamide, polyesters, and rubber, and there were notable differences in the removal of polyesters and rubber MNPs smaller than 5 μm at three of the four plants. Overall, these results increase our understanding of MNP removal during conventional drinking water treatment and improve our understanding of human exposure to MNPs through drinking water.