Abstract
Wastewater treatment plants (WWTPs) are one of the most important ways of releasing microplastics (MPs) into the environment. In this study, the size, number, color, and shape of MPs during the wastewater treatment process were investigated in six WWTPs with different processes, which include WWTPs A and B (activated sludge process, ASP), WWTP C and D (aerated lagoon, AL), WWTP E (sequencing batch reactor process, SBR), and WWTP F (stabilization pond, SP). The MP particles were detected by the polarized light microscopy. In all six WWTPs, the clear color was observed as the dominant color in the effluent. Among the forms of MPs, fibers had the highest removal efficiency in WWTPs A (97.3%), B (99.2%), C (95.5%), and D (94.3%). In both WWTPs E and F, the highest removal rate of MP shapes was related to films (96.1%) and granules (86.1%), respectively. MPs with size 25–125 μm had the highest amount (0.39 to 4.08 MP/L) in the effluent of WWTPs compared to larger sizes. With respect to the type of the wastewater treatment process, the number of MPs during the treatment process decreased from 3.75–25.31 to 0.51–6.28MP/L. Based on the results of this study, ASP with a removal rate of 91.87% had the highest efficiency compared to other processes. However, daily 4.95 × 104 to 1.49 × 108 MP enter the environment via the effluent of these WWTPs. The study recommends reducing the use of MPs and plasticizers in widely used products as much as possible and replacing them with nature-friendly materials.
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Abeynayaka, A., Werellagama, I., Ngoc-Bao, P., Hengesbaugh, M., Gajanayake, P., Nallaperuma, B., Karkour, S., Bui, X.-T., & Itsubo, N. (2022). Microplastics in wastewater treatment plants. Current Developments in Biotechnology and Bioengineering, 311–337. https://doi.org/10.1016/B978-0-323-99874-1.00010-5
Al-Azzawi, M. S., Funck, M., Kunaschk, M., Von der Esch, E., Jacob, O., Freier, K. P., Schmidt, T. C., Elsner, M., Ivleva, N. P., & Tuerk, J. (2022). Microplastic sampling from wastewater treatment plant effluents: Best-practices and synergies between thermoanalytical and spectroscopic analysis. Water Research, 219, 118549. https://doi.org/10.1016/j.watres.2022.118549
Alvim, C. B., Valiente, S. N., Bes-Piá, M., & Mendoza-Roca, J. (2022). Methodology for removing microplastics and other anthropogenic microparticles from sludge dewatering system. Journal of Environmental Management, 314, 115010. https://doi.org/10.1016/j.jenvman.2022.115010
Becucci, M., Mancini, M., Campo, R., & Paris, E. (2022). Microplastics in the Florence wastewater treatment plant studied by a continuous sampling method and Raman spectroscopy: A preliminary investigation. Science of The Total Environment, 808, 152025. https://doi.org/10.1016/j.scitotenv.2021.152025
Chand, R., Kohansal, K., Toor, S., Pedersen, T. H., & Vollertsen, J. (2022). Microplastics degradation through hydrothermal liquefaction of wastewater treatment sludge. Journal of Cleaner Production, 335, 130383. https://doi.org/10.1016/j.jclepro.2022.130383
De-la-Torre, G. E., Pizarro-Ortega, C. I., Dioses-Salinas, D. C., Loayza, J. C., Sanchez, J. S., Meza-Chuquizuta, C., Espinoza-Morriberón, D., Rakib, M. R. J., Ben-Haddad, M., & Dobaradaran, S. (2022). Are we underestimating floating microplastic pollution? A quantitative analysis of two sampling methodologies. Marine Pollution Bulletin, 178, 113592. https://doi.org/10.1016/j.marpolbul.2022.113592
Dong, S., Gao, P., Li, B., Feng, L., Liu, Y., Du, Z., & Zhang, L. (2022). Occurrence and migration of microplastics and plasticizers in different wastewater and sludge treatment units in municipal wastewater treatment plant. Frontiers of Environmental Science & Engineering, 16(11), 142. https://doi.org/10.1007/s11783-022-1577-9
Eibes, P. M., & Gabel, F. (2022). Floating microplastic debris in a rural river in Germany: Distribution, types and potential sources and sinks. Science of The Total Environment, 816, 151641. https://doi.org/10.1016/j.scitotenv.2021.151641
Estahbanati, S., & Fahrenfeld, N. L. (2016). Influence of wastewater treatment plant discharges on microplastic concentrations in surface water. Chemosphere, 162, 277–284. https://doi.org/10.1016/j.chemosphere.2016.07.083
Gao, Z., Chen, L., Cizdziel, J., & Huang, Y. (2023a). Research progress on microplastics in wastewater treatment plants: A holistic review. Journal of Environmental Management, 325, 116411. https://doi.org/10.1016/j.jenvman.2022.116411
Gao, Z., Cizdziel, J. V., & Chen, L. (2023b). Microplastics profile in sludge from a university wastewater treatment plant and the influence of chemical digestions on Nile red stained microplastics. Journal of Environmental Chemical Engineering, 11(3), 109671. https://doi.org/10.1016/j.jece.2023.109671
Graney, G. (2015). Slipping through the cracks: How tiny plastic microbeads are currently escaping water treatment plants and international pollution regulation. Fordham Int’l LJ, 39, 1023.
Hajji, S., Ben-Haddad, M., Abelouah, M. R., De-la-Torre, G. E., & Alla, A. A. (2023). Occurrence, characteristics, and removal of microplastics in wastewater treatment plants located on the Moroccan Atlantic: The case of Agadir metropolis. Science of the Total Environment, 862, 160815. https://doi.org/10.1016/j.scitotenv.2022.160815
Haque, M. M., Nupur, F. Y., Parvin, F., & Tareq, S. M. (2022). Occurrence and characteristics of microplastic in different types of industrial wastewater and sludge: A potential threat of emerging pollutants to the freshwater of Bangladesh. Journal of Hazardous Materials Advances, 8, 100166. https://doi.org/10.1016/j.hazadv.2022.100166
Harley-Nyang, D., Memon, F. A., Jones, N., & Galloway, T. (2022). Investigation and analysis of microplastics in sewage sludge and biosolids: A case study from one wastewater treatment works in the UK. Science of the Total Environment, 823, 153735. https://doi.org/10.1016/j.scitotenv.2022.153735
Jiang, J., Wang, X., Ren, H., Cao, G., Xie, G., Xing, D., & Liu, B. (2020). Investigation and fate of microplastics in wastewater and sludge filter cake from a wastewater treatment plant in China. Science of the Total Environment, 746, 141378. https://doi.org/10.1016/j.scitotenv.2020.141378
Khan, N. A., Khan, A. H., Maldonado, E. A. L., Alam, S. S., López, J. R. L., Herrera, P. F. M., Mohamed, B. A., Mahmoud, A. E. D., Abutaleb, A., & Singh, L. (2022). Microplastics: Occurrences, treatment methods, regulations and foreseen environmental impacts. Environmental Research, 114224. https://doi.org/10.1016/j.envres.2022.114224
Kılıç, E., Yücel, N., & Şahutoğlu, S. M. (2023). Microplastic composition, load and removal efficiency from wastewater treatment plants discharging into Orontes River. International Journal of Environmental Research, 17(2), 25. https://doi.org/10.1007/s41742-023-00514-0
Koyuncuoğlu, P., & Erden, G. (2023). Microplastics in municipal wastewater treatment plants: A case study of Denizli/Turkey. Frontiers of Environmental Science & Engineering, 17(8), 99. https://doi.org/10.1007/s11783-023-1699-8
Krishnan, R. Y., Manikandan, S., Subbaiya, R., Karmegam, N., Kim, W., & Govarthanan, M. (2023). Recent approaches and advanced wastewater treatment technologies for mitigating emerging microplastics contamination–A critical review. Science of The Total Environment, 858, 159681. https://doi.org/10.1016/j.scitotenv.2022.159681
Kutralam-Muniasamy, G., Shruti, V., Pérez-Guevara, F., & Roy, P. D. (2023). Microplastic diagnostics in humans: “The 3Ps” progress, problems, and prospects. Science of The Total Environment, 856, 159164. https://doi.org/10.1016/j.scitotenv.2022.159164
Kwon, H. J., Hidayaturrahman, H., Peera, S. G., & Lee, T. G. (2022). Elimination of microplastics at different stages in wastewater treatment plants. Water, 14(15), 2404. https://doi.org/10.3390/w14152404
Lares, M., Ncibi, M. C., Sillanpää, M., & Sillanpää, M. (2018). Occurrence, identification and removal of microplastic particles and fibers in conventional activated sludge process and advanced MBR technology. Water Research, 133, 236–246. https://doi.org/10.1016/j.watres.2018.01.049
LaRue, R. J., Patterson, B., O’Brien, S., & Latulippe, D. R. (2022). Evaluation of membrane fouling by microplastic particles in tertiary wastewater treatment processes. ACS ES&T Water, 2(6), 955–966. https://doi.org/10.1021/acsestwater.1c00430
Leslie, H. A., Van Velzen, M. J., Brandsma, S. H., Vethaak, A. D., Garcia-Vallejo, J. J., & Lamoree, M. H. (2022). Discovery and quantification of plastic particle pollution in human blood. Environment International, 163, 107199. https://doi.org/10.1016/j.envint.2022.107199
Liu, W., Zhang, J., Liu, H., Guo, X., Zhang, X., Yao, X., Cao, Z., & Zhang, T. (2021). A review of the removal of microplastics in global wastewater treatment plants: Characteristics and mechanisms. Environment International, 146, 106277. https://doi.org/10.1016/j.envint.2020.106277
Lofty, J., Muhawenimana, V., Wilson, C., & Ouro, P. (2022). Microplastics removal from a primary settler tank in a wastewater treatment plant and estimations of contamination onto European agricultural land via sewage sludge recycling. Environmental Pollution, 304, 119198. https://doi.org/10.1016/j.envpol.2022.119198
Luo, Y., Xie, H., Xu, H., Zhou, C., Wang, P., Liu, Z., Yang, Y., Huang, J., Wang, C., & Zhao, X. (2023). Wastewater treatment plant serves as a potentially controllable source of microplastic: Association of microplastic removal and operational parameters and water quality data. Journal of Hazardous Materials, 441, 129974. https://doi.org/10.1016/j.jhazmat.2022.129974
Martín-García, A. P., Egea-Corbacho, Á., Franco, A. A., Rodríguez-Barroso, R., Coello, M. D., & Quiroga, J. M. (2023). Grab and composite samples: Variations in the analysis of microplastics in a real wastewater treatment plant in the South of Spain. Journal of Environmental Chemical Engineering, 11(2), 109486. https://doi.org/10.1016/j.jece.2023.109486
Mason, S. A., Garneau, D., Sutton, R., Chu, Y., Ehmann, K., Barnes, J., Fink, P., Papazissimos, D., & Rogers, D. L. (2016). Microplastic pollution is widely detected in US municipal wastewater treatment plant effluent. Environmental Pollution, 218, 1045–1054. https://doi.org/10.1016/j.envpol.2016.08.056
Mishra, S., Singh, R. P., Rout, P. K., & Das, A. P. (2022). Membrane bioreactor (MBR) as an advanced wastewater treatment technology for removal of synthetic microplastics. Development in Wastewater Treatment Research and Processes, 45–60. https://doi.org/10.1016/B978-0-323-85583-9.00022-3
Monteiro, S. S., & da Costa, J. P. (2022). Methods for the extraction of microplastics in complex solid, water and biota samples. Trends in Environmental Analytical Chemistry, 33, e00151. https://doi.org/10.1016/j.teac.2021.e00151
Naji, A., Azadkhah, S., Farahani, H., Uddin, S., & Khan, F. R. (2021). Microplastics in wastewater outlets of Bandar Abbas city (Iran): A potential point source of microplastics into the Persian Gulf. Chemosphere, 262, 128039. https://doi.org/10.1016/j.chemosphere.2020.128039
Nguyen, P.-D., Tran, Q.-V., Le, T.-T., Nguyen, Q.-H., Kieu-Le, T.-C., & Strady, E. (2023). Evaluation of microplastic removal efficiency of wastewater-treatment plants in a developing country, Vietnam. Environmental Technology & Innovation, 102994. https://doi.org/10.1016/j.eti.2022.102994
Reddy, A. S., & Nair, A. T. (2022) The fate of microplastics in wastewater treatment plants: An overview of source and remediation technologies. Environmental Technology & Innovation, 102815. https://doi.org/10.1016/j.eti.2022.102815
Ridall, A., Farrar, E., Dansby, M., & Ingels, J. (2023). Influence of wastewater treatment plants and water input sources on size, shape, and polymer distributions of microplastics in St. Andrew Bay, Florida, USA. Marine Pollution Bulletin, 187, 114552. https://doi.org/10.1016/j.marpolbul.2022.114552
Sadia, M., Mahmood, A., Ibrahim, M., Irshad, M. K., Quddusi, A. H. A., Bokhari, A., Mubashir, M., Chuah, L. F., & Show, P. L. (2022). Microplastics pollution from wastewater treatment plants: A critical review on challenges, detection, sustainable removal techniques and circular economy. Environmental Technology & Innovation, 102946. https://doi.org/10.1016/j.eti.2022.102946
Sakali, A., Coello, D., Brigui, J., Albendín, G., Arellano, J., Quiroga, J. M., & Rodríguez-Barroso, R. (2022). Annual estimates of microplastics in municipal sludge treatment plants in southern Spain. Journal of Water Process Engineering, 49, 102956. https://doi.org/10.1016/j.jwpe.2022.102956
Shan, W., Li, B., Zhang, H., Zhang, Z., Wang, Y., Gao, Z., & Li, J. (2022). Distribution, characteristics and daily fluctuations of microplastics throughout wastewater treatment plants with mixed domestic—Industrial influents in Wuxi City, China. Frontiers of Environmental Science & Engineering, 16, 1–9. https://doi.org/10.1016/j.watres.2023.119569
Simon, M., van Alst, N., & Vollertsen, J. (2018). Quantification of microplastic mass and removal rates at wastewater treatment plants applying Focal Plane Array (FPA)-based Fourier Transform Infrared (FT-IR) imaging. Water Research, 142, 1–9. https://doi.org/10.1016/j.watres.2018.05.019
Sönmez, V. Z., Akarsu, C., & Sivri, N. (2023). Impact of coastal wastewater treatment plants on microplastic pollution in surface seawater and ecological risk assessment. Environmental Pollution, 318, 120922. https://doi.org/10.1016/j.envpol.2022.120922
Stein, M. M. (2015) 21st Century Cures Draft Includes Changes To Medicare Coverage, Pay. Inside CMS, 18, 1–13. https://www.jstor.org/stable/26702752
Tadsuwan, K., & Babel, S. (2022a). Microplastic abundance and removal via an ultrafiltration system coupled to a conventional municipal wastewater treatment plant in Thailand. Journal of Environmental Chemical Engineering, 10(2), 107142. https://doi.org/10.1016/j.jece.2022.107142
Tadsuwan, K., & Babel, S. (2022b). Unraveling microplastics removal in wastewater treatment plant: A comparative study of two wastewater treatment plants in Thailand. Chemosphere, 307, 135733. https://doi.org/10.1016/j.chemosphere.2022.135733
Takdastan, A., Niari, M. H., Babaei, A., Dobaradaran, S., Jorfi, S., & Ahmadi, M. (2021). Occurrence and distribution of microplastic particles and the concentration of Di 2-ethyl hexyl phthalate (DEHP) in microplastics and wastewater in the wastewater treatment plant. Journal of Environmental Management, 280, 111851. https://doi.org/10.1016/j.jenvman.2020.111851
Tang, N., Liu, X., & Xing, W. (2020). Microplastics in wastewater treatment plants of Wuhan, Central China: Abundance, removal, and potential source in household wastewater. Science of the Total Environment, 745, 141026. https://doi.org/10.1016/j.scitotenv.2020.141026
Vuori, L., & Ollikainen, M. (2022). How to remove microplastics in wastewater? A cost-effectiveness analysis. Ecological Economics, 192, 107246. https://doi.org/10.1016/j.ecolecon.2021.107246
Wang, M.-H., Chen, C.-F., Albarico, F. P. J. B., Chen, C.-W., & Dong, C.-D. (2022). Occurrence and distribution of phthalate esters and microplastics in wastewater treatment plants in Taiwan and their toxicological risks. Chemosphere, 307, 135857. https://doi.org/10.1016/j.chemosphere.2022.135857
Wu, X., Zhao, X., Chen, R., Liu, P., Liang, W., Wang, J., Teng, M., Wang, X., & Ga, S. (2022). Wastewater treatment plants act as essential sources of microplastic formation in aquatic environments: A critical review. Water Research, 118825.https://doi.org/10.1016/j.watres.2022.118825
Yang, F., Li, D., Zhang, Z., Wen, L., Liu, S., Hu, E., Li, M., & Gao, L. (2022). Characteristics and the potential impact factors of microplastics in wastewater originated from different human activity. Process Safety and Environment Protection, 166, 78–85. https://doi.org/10.1016/j.psep.2022.07.048
Yang, J., Monnot, M., Sun, Y., Asia, L., Wong-Wah-Chung, P., Doumenq, P., & Moulin, P. (2023). Microplastics in different water samples (seawater, freshwater, and wastewater): Removal efficiency of membrane treatment processes. Water Research, 232, 119673. https://doi.org/10.1016/j.watres.2023.119673
Zhang, Z., Liu, W., Gao, Q., Huang, F., Kang, Y., Pan, Y., Luo, G., Zhou, X., Fan, L., & Wang, A. (2023). Microplastics extraction from wastewater treatment plants: Two-step digestion pre-treatment and application. Water Research, 119569. https://doi.org/10.1016/j.watres.2023.119569
Zhao, K., Wei, Y., Dong, J., Zhao, P., Wang, Y., Pan, X., & Wang, J. (2022). Separation and characterization of microplastic and nanoplastic particles in marine environment. Environmental Pollution, 297, 118773. https://doi.org/10.1016/j.envpol.2021.118773
Ziajahromi, S., Neale, P. A., Rintoul, L., & Leusch, F. D. (2017). Wastewater treatment plants as a pathway for microplastics: Development of a new approach to sample wastewater-based microplastics. Water Research, 112, 93–99. https://doi.org/10.1016/j.watres.2017.01.042
Ziajahromi, S., Neale, P. A., Silveira, I. T., Chua, A., & Leusch, F. D. (2021). An audit of microplastic abundance throughout three Australian wastewater treatment plants. Chemosphere, 263, 128294. https://doi.org/10.1016/j.chemosphere.2020.128294
Zöhre, K., & James, A. (2022). Effectiveness of microplastics removal in wastewater treatment plants: A critical analysis of wastewater treatment processes. Journal of Environmental Chemical Engineering, 107831. https://doi.org/10.1016/j.jece.2022.107831
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The authors would like to acknowledge Social Determinants of Health Research Center, Ardabil University of Medical Sciences, Ardabil, Iran, for financial and instrumental supports (Grant No. IR.ARUMS.REC.1400.328).
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Highlights
• MPs with size 25-125μm had the highest amount in the effluent of WWTPs.
• The highest MPs removal efficiency was obtained by ASP (89.4% - 91.87%).
• Daily 4.95×104 to 1.49×108 MP enter the environment through the effluent of WWTPs.
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Niari, M.H., Jaafarzadeh, N., Dobaradaran, S. et al. Release of Microplastics to the Environment Through Wastewater Treatment Plants: Study on Four Types of Wastewater Treatment Processes. Water Air Soil Pollut 234, 589 (2023). https://doi.org/10.1007/s11270-023-06594-0
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DOI: https://doi.org/10.1007/s11270-023-06594-0