Microplastics in Urban Wastewater: A Vector for Chemical and Biological Pollutants with Emerging Health Risks

The widespread usage of plastic items, plastics are often seen as a serious concern especially in metropolitan areas. This study investigates the abundance, geographical distribution and composition of micro-plastics (MPs), adsorbed contaminants (Heavy metals, microbes) on MPs in urban wastewater in Faisalabad, Pakistan, with a focus on the effects of human activities. To support this study, analyses of water quality and the connection between microplastic contaminants and the physicochemical characteristics of water quality were also conducted. Faisalabad, a sizable industrial and inhabited city has significant micro-plastics (MPs) pollution in its wastewater systems as a result of poor plastic waste management. Wastewater samples from 14 main disposal sites were analyzed for micro-plastics (MPs) concentration, form, polymer composition and relationship to adsorbed contaminants and water quality variables. The results showed that MPs were present in all samples, with an average concentration of 2281±0.19 MPs/m³ and a maximum of 9256±0.35 MPs/m³ in dense areas. The most common type was large sized MPs (300-500 μm) which included 50.5% fragments and 31.5% fibers. The three main polymers identified by FTIR analysis were polyethylene (PE) 37%, polypropylene (PP) 29%, and polystyrene (PS) 25%. Human consumption appears to be the main source of MP, as evidenced by the strong correlation between MP content and water quality indicators. The findings confirmed that micro-plastic presence is associated with increased levels of TS, conductivity, turbidity, BOD₅, COD, Temperature, along with reduced DO, pH, NO₃-N, NO₂-N, and NH₄-N. MPs extracted from the waste water are loaded with heavy metals Pb, Cr, Cd, Cu, Zn, Ni and As. Bacterial Colonization Potential Index (BCPI) further explore a significant impact of MPs on bacterial colonization and health risk index. This study highlights the need of improving regulations for the handling of plastic waste in cities like Faisalabad in order to reduce MP contamination.