Mass Concentration and Removal Characteristics of Microplastics and Nanoplastics in a Drinking Water Treatment Plant

The occurrence and removal of microplastics (MPs) in drinking water treatment plants (DWTPs) have been evaluated based on particle number, while the mass concentration and removal characteristics based on the mass of MPs, and especially nanoplastics (NPs), remain unknown. This study employed pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) to determine the mass concentration of MPs and NPs with different size ranges (0.01-1, 1-50, and 50-1000 μm) across the entire treatment process in a DWTP. The total polymers were measured at 9.63 ± 1.52 μg/L in raw water and 0.77 ± 0.05 μg/L in treated water, with the dominant polymers being polypropylene and polyethylene terephthalate. NPs (0.01-1 μm) accounted for only 3.2-5.3% of the total polymers, with an average concentration of 0.38 μg/L in raw water and 0.04 μg/L in treated water. Notably, NPs and sub-MPs (1-50 μm) demonstrated relatively low efficiency in the DWTP at 88.9 ± 3.2 and 88.0 ± 2.5%, respectively, compared with that of the large MPs (50-1000 μm) at 92.9 ± 0.3%. Overall, this study examined the occurrence of MPs and NPs, in a DWTP, emphasizing the significance of considering the mass concentration of MPs and NPs when assessing their pollution levels and removal characteristics.