Identification of microplastics in conventional drinking water treatment plants in Tehran, Iran

The presence of microplastics (MPs), as an emerging pollutant is a growing concern in drinking water, yet most of the studies have been carried out in surface waters and wastewater treatment plants and there are few studies on MPs in drinking water treatment plants (DWTPs). This study investigates these particles in three different conventional DWTPs in the city of Tehran, Iran, and aims to analyze these particles down to the size of 1 mu m. A scanning electron microscope was utilized in this study to quantitatively analyze MPs. Accordingly, the average abundance of MPs in raw and treated water samples varied from 1996 +/- 268 to 2808 +/- 80 MPs L-1 and 971 +/- 103 to 1401 +/- 86 MPs L-1, respectively. While particles smaller than 10 mu m comprised 65-87% of MPs. Moreover, mu-Raman spectroscopy was used to characterize MPs. As the results, polypropylene, polyethylene terephthalate, and polyethylene were the most abundant identified polymers among MPs, comprising more than 53% of particles. Additionally, MPs were categorized as fibers, fragments, and spheres. This study fills the knowledge gap of MPs presence in Tehran conventional DWTPs which is of high importance since they supply drinking water for more than 8 million people and investigates the performance of conventional DWTPs in removing MPs.

Automated summary

This study investigated the presence of microplastics in three conventional drinking water treatment plants in Tehran, Iran, and found that the average abundance of microplastics varied between different plants. Polypropylene, polyethylene terephthalate, and polyethylene were identified as the most common polymers among microplastics, comprising over 53% of particles. The study also categorized microplastics into fibers, fragments, and spheres.