Occurrence of Microplastics in Influent, Sewage Sludge and Effluent of Municipal Wastewater Treatment Plant, A Case Study Center of Iran, Qom city

Document Type : Original Research Paper

Authors

1 Student Research Committee, Qom University of Medical Sciences, Qom, Iran

2 Research Center for Environmental Pollutants, Qom University of Medical Sciences, Qom, Iran

3 Department of Epidemiology and Biostatistics, Faculty of Health, Qom University of Medical Sciences, Qom, Iran

4 Department of Public Health, Faculty of Health, Qom University of Medical Sciences, Qom, Iran

5 Monitoring and monitoring center for water and sewage quality, Water and Sewerage Company, Qom, Iran

6 School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, B15 2TT Birmingham, United Kingdom

7 Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

10.22059/poll.2025.398193.3013

Abstract

The presence of Microplastics (MPs) in the environment poses a significant threat to both humans and ecosystems health. One common source of environmental MPs pollution is the sludge and effluent discharged by wastewater treatment facilities if no specific measures are implemented for post process MP removal. The purpose of this study is to investigate the MPs removal capacity under different conditions by analysis of MPs in the inlet wastewater, outlet effluent, and sludge of one of the wastewater treatment plants (WWTPs) in Qom city, Iran. Monthly sampling was conducted in spring and summer of 2022, resulting in analysis of a total of 18 samples from wastewater, effluent, and sludge. MPs were identified and separated according to established guidelines followed by further analysis using scanning electron microscopy (SEM) and µ-Raman spectroscopy. The average MPs concentration in wastewater and effluent were 710± 34.67 MP/L and 51± 4.42 MP/L, respectively, while it was 30.76±7.19MP/g in sludge. The treatment plant demonstrated an average MPs removal efficiency of 92.81%. Overall, polyethylene terephthalate (PET) and fibers were the most frequent type and shape of MPs identified across all samples. The dominant sizes of MPs in wastewater and sludge ranged between 250-500 µm, while in the effluent, the MPs were primarily within the 250-100 µm. Based on the findings, it is estimated that 2652×106 MPs enter the environment daily through effluent and contributing to the pollution in air, soil, and surface water. The results of this study showed that sludge and effluent from WWTP are rich in MPs, and if used as fertilizer or to irrigate fields and crops, they can cause high levels of MPs to accumulate in the soil, polluting ecosystems and posing serious risks to organisms.

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Main Subjects


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