Point-source tracking of microplastics in sewerage systems. Finding the culprit.

Prior microplastic (MP) research has focused more on the efficiency of removal techniques within wastewater treatment plants (WWTP), with comparatively less emphasis placed on identifying and understanding the sources of MPs. In this study, the presence of MP in wastewater from various sources and their associated WWTPs was investigated. Utilising focal plane array micro Fourier Transform Infrared spectroscopy (FPA-μFTIR), the chemical composition, size distribution, and mass of MPs were quantified. Notably, wastewater generated from an industrial laundry facility exhibited the highest MP concentration of 6900 counts L or 716 μg L. Domestic sewage contained MP levels (1534 counts L; 158 μg L) similar to those at the WWTPs (1640 counts L; 114 μg L). Polyester was identified as a significant component in most of the sources, predominantly originating from the shedding of fibres during textile washing. Additionally, a post-processing software was employed to compare two methods for fibre identification: aspect ratio and elongation ratio. These findings underscore the potential environmental impact of domestic activities and laundry washing on wastewater MP content.