Occurrence and removal of microplastics in a municipal wastewater treatment plant with conventional activated sludge process: A case study in Isfahan, Iran
Background: Microplastics (MPs) are nowadays found in the air and in various terrestrial and aquatic environments and have become emerging pollutants. These particles can absorb other chemicals and microbial contaminants and release them into the environment and food chain. Despite the high effic...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Kerman University of Medical Sciences
2023-02-01
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| Series: | Environmental Health Engineering and Management |
| Subjects: | |
| Online Access: | http://ehemj.com/browse.php?a_id=1064&sid=1&slc_lang=en&ftxt=1 |
| Summary: | Background: Microplastics (MPs) are nowadays found in the air and in various terrestrial and aquatic
environments and have become emerging pollutants. These particles can absorb other chemicals and
microbial contaminants and release them into the environment and food chain. Despite the high
efficiency of wastewater treatment plants (WWTPs) in removing MPs, WWTPs are still one of the
major sources of MPs discharge to the environment. This study was conducted to evaluate the efficiency
of MPs removal in a municipal WWTP with conventional activated sludge in Iran.
Methods: MPs particles were counted using a stereomicroscope after the initial preparation steps
(sieving, chemical digestion with the catalytic wet peroxidation-oxidation and density separation with
NaCl) and then analyzed for particle composition using a Raman micro-spectrometer.
Results: MPs concentration in the influent, grit chamber, primary sedimentation tank, and effluent
were 843.2 ± 147.5, 315.5 ± 54.7, 80.2 ± 19.1, and 11.13 ± 3.14 items/L, respectively. The overall MPs
removal efficiency of the WWTP was 98.7%, with the grit chamber, primary sedimentation tank, and
secondary sedimentation tank removed 62.6%, 27.9%, and 8.2% of the total MPs, respectively. The most
abundant polymers were polypropylene (PP) and polyethylene (PE).
Conclusion: Despite the effective removal of MPs in WWTP, on average 4.47 × 1011 ± 1.03 × 1011 MPs
are discharged into the receiving waters through the effluent of this WWTP annually. This means that
WWTPs can be one of the major sources of MPs in the environment and efforts should be made to
increase the efficiency of WWTPs and equip them with advanced technologies. |
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| ISSN: | 2423-3765 2423-4311 |