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Fibers and fragments photographed under microscope (a red fiber; b blue fiber; c green fragment; d black fragment)
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The widespread use of synthetic polymers has made microplastic (MP) a new type of contaminant that has attracted worldwide attention. Studies have shown that wastewater treatment plants (WWTPs) are an important source of MP collection in the natural environment. This study investigated the removal efficiency and migration characteristics of MPs by...
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Municipal wastewater treatment plants (WWTPs) are considered to be major contributors of microplastics to the aquatic environment. Detailed research in China, which is relevant to the local situation, remains in the initial stage. Herein, the microplastic abundance, morphology, and removal efficiency of two WWTPs (C and P) equipped with tertiary tr...
Citations
... Pittura et al. (2021) reported that the concentration of MPs in primary sludge from the primary settler, secondary sludge from the secondary settler and dewatered sludge was 1.67 MPs.gTS −1 , 5.3 MPs.gTS −1, and 4.74 MPs.gTS −1 , respectively, in a municipal WWTP in Italy with an average flow rate of 18,000 m 3 /day [42]. In a study conducted by Ren et al. (2020), the abundance of MP in dehydrated and dried sludge was found to be 2.92 × 10 ³ MP/kg in a WWTP in China [43]. The WWTP, which treats municipal wastewater and stormwater, has a capacity of 300,000 m³ per day and produces 108 tons of dried sludge per day. ...
... Pittura et al. (2021) reported that the concentration of MPs in primary sludge from the primary settler, secondary sludge from the secondary settler and dewatered sludge was 1.67 MPs.gTS −1 , 5.3 MPs.gTS −1, and 4.74 MPs.gTS −1 , respectively, in a municipal WWTP in Italy with an average flow rate of 18,000 m 3 /day [42]. In a study conducted by Ren et al. (2020), the abundance of MP in dehydrated and dried sludge was found to be 2.92 × 10 ³ MP/kg in a WWTP in China [43]. The WWTP, which treats municipal wastewater and stormwater, has a capacity of 300,000 m³ per day and produces 108 tons of dried sludge per day. ...
... The WWTP, which treats municipal wastewater and stormwater, has a capacity of 300,000 m³ per day and produces 108 tons of dried sludge per day. Ren et al. (2020) reported that in this WWTP, where the incoming MP abundance was 4.8 × 10 9 MP/day, 3.15 × 10 8 MPs were transferred to sludge for landfill treatment [43]. ...
There is a lack of information on the level of microplastic (MP) contamination in leachate, which contains highlevels of pollutants and has considerable complexity to treat, originating from landfills. In this review, thesources, abundance, and characteristics (polymer type, size, shape) of MPs in landfill leachates were presented.Subsequently, the limited number of studies on MPs released into the environment from the environment fromthe leachate of uncontrolled landfills were summarised. In the next section, possible remediation approaches(physical treatment processes, chemical treatment processes, biological treatment processes, and constructedwetlands) for MPs in landfill leachate were discussed. Finally, research gaps and recommendations for futurestudies on MPs in landfill leachates were presented. As a result of the review, it was determined that there is anurgent need for a standardized MP analysis method. Furthermore, the necessity for an increased number ofstudies on the removal of MPs from landfill leachate with high efficiency and low cost was highlighted. It wasemphasized that reducing the amount of plastic waste in landfills and reducing the amount of MP in landfillleachate can be achieved by taking and implementing urgent measures through public policies.
... The retained MPs are either concentrated in the sludge (Michielssen et al., 2016;Xu et al., 2019) or skimmed off with the grit and grease (Chand et al., 2021;Rasmussen et al., 2021). The larger-sized MPs have been reported residing in grit, grease, and primary sludge, while smaller MPs seem to have a higher probability to reach the outlet (Lusher et al., 2017;Murphy et al., 2016;Ren et al., 2020). Sun et al. (2019) reported that 35-59 % of MPs were removed by pre-treatment and 50-98 % by primary treatment, while Iyare et al. (2020) found that tertiary treatment could further remove 5-20 %. ...
... Schmidt et al. (2020) for instance found 4-4.5 × 10 5 MP m − 3 in the effluent of 79 German WWTPs. Similarly, Ren et al. (2020) reported a daily discharge of 8.7 × 10 8 MPs from a Chinese WWTP treating combined municipal sewage and stormwater. Many studies on MP retainment at WWTPs overlook that WWTPs differ widely in the technology they apply. ...
... Blank correction can hence bias the data instead of improving it. Many studies took the same approach for similar reasons, for example Lares et al. (2018), Liu et al. (2019), Ren et al. (2020), and Simon et al. (2018). Instead, these studies reported background contamination to qualify how trustworthy the data was. ...
... Disposal of MPs separated from wastewater in WWTPs is another problem. Since MPs remain in the sludge even if various processes such as dewatering and stabilization are applied to the sludge, deficiencies in the management of sewage sludge and uncontrolled use of sludge in agricultural areas lead to a serious MP release into the environment (Ren et al. 2020;Harley-Nyang et al. 2022). Some studies conducted in recent years have shown that MPs separated from wastewater in WWTPs can be converted into economically valuable materials Luo et al. 2023). ...
... In secondary treatment, MPs in wastewater are separated from wastewater by adsorption to activated sludge and precipitation by gravity in secondary settling tanks (Acarer 2023a). In other words, in secondary treatment, MPs in wastewater are trapped in the sludge in secondary settling tanks (Ren et al. 2020). Can et al. (2023) reported that MPs were removed with 87% efficiency through the A2/O biological tank and secondary settling tank in Bursa WWTP. ...
The effluent of WWTPs is an important source of microplastics (MP) for the aquatic environment. In this review study, MPs in wastewater treatment plants (WWTP) in Türkiye and their removal from WWTPs are reviewed for the first time. First, MP characteristics in the influent and effluent of WWTPs in Türkiye are discussed. In the next section, the abundance of MPs in the influent and effluent of WWTPs in Türkiye and the MP removal efficiency of WWTPs in Türkiye are evaluated. Then, the results of studies on MP abundance and characteristics in Türkiye's aquatic environments are presented and suggestions are made to reduce MPs released from WWTPs into the receiving environments. Strategies for reducing MPs released to the receiving environment from WWTPs of Türkiye are summarized. In the last section, research gaps regarding MPs in WWTPs in Türkiye are identified and suggestions are made for future studies. This review paper provides a comprehensive assessment of the abundance, dominant characteristics, and removal of MPs in WWTPs in Türkiye, as well as the current status and deficiencies in Türkiye. Therefore, this review can serve as a scientific guide to improve the MP removal efficiency of WWTPs in Türkiye.
... Table 1 summarizes the microplastic concentrations in the influent, effluent, and their removal rate in WWTPs. Because there is no harmonization of methodologies, studies in Table 1 reported results in MPs/L or MP/L − 1 [1,[42][43][44]47,48,[50][51][52][53]56,60,[68][69][70][71][73][74][75]78,79,[81][82][83], items/L [59,63,75,80], particles/L [58,61,62,64,67,72,76] and n/L [37,55,57,65,66]. ...
... We cannot rule out the fact that tertiary treatment enhances microplastics removal after the previous treatment stages but in most studies the contribution of the tertiary stage is minimal based on the analysis of the microplastics removal rate per treatment stage. Early research that compared microplastics removal in the different treatment stages showed that the primary, secondary and tertiary treatments have a microplastic removal rate of 35.6 %, 36.3 %, and 10.0 % respectively, with an overall removal rate of 81.9 % [78], indicating that the tertiary stage was less efficient in the removal of microplastics. In this study, the microplastic concentrations were 16.0, 10.3, 4.5, and 2.9 MP/L in the influent, primary, secondary, and tertiary treatments respectively [78]. ...
... Early research that compared microplastics removal in the different treatment stages showed that the primary, secondary and tertiary treatments have a microplastic removal rate of 35.6 %, 36.3 %, and 10.0 % respectively, with an overall removal rate of 81.9 % [78], indicating that the tertiary stage was less efficient in the removal of microplastics. In this study, the microplastic concentrations were 16.0, 10.3, 4.5, and 2.9 MP/L in the influent, primary, secondary, and tertiary treatments respectively [78]. The impact of the tertiary treatment stage in microplastics removal was also reported to be somewhat low compared to the primary and secondary treatments in WWTPs in South-eastern China. ...
Microplastics are ubiquitous in the environment which has attracted increasing environmental, health, socio-economic, and regulatory concerns. Exposure to these emerging pollutants has been associated with certain disorders in both animals and humans. Wastewater treatment plants (WWTPs) are a reservoir of microplastics due to the diverse influent sources. They also serve as a point source of microplastics pollution in the environment due to their inability to completely remove these pollutants in the final effluent. The present review discusses the physicochemical properties - shapes, polymer composition, and sizes of microplastics present in WWTPs. The impact of these properties on microplastics removal efficiency in WWTPs and the other factors influencing their occurrence and removal are further elucidated. The impact of effluent microplastics on the environment is also provided. Finally, microplastics abatement measures such as redesigning washing machine filters and the efficacy of policies on regulating plastics pollution are highlighted. Investigations into microplastics mass instead of particle number only, will constitute a future research direction which will increase our understanding of microplastics nexus in wastewater pollution and treatment.
... (2019) recommended to consider MPs as these plastic particles within the range between 1 and 5000 µm. However, the lower limit taken by investigators is usually higher, with values that go from 20 µm to 150 µm (Alvim et al., 2020;Cao et al., 2020;Dris et al., 2015;Lin et al., 2018;Liu et al., 2019;Jiang et al., 2020;Ren et al., 2020;Ruan et al., 2019). The upper limit considered in most cases is 5000 µm, although narrower ranges have also been considered, such as 45 -400 µm (Carr et al., 2016) and 100 -500 µm (Simon et al., 2018). ...
The ubiquitous presence of microplastics (MPs) in natural water bodies reflects the global issue regarding these micropollutants. The main problem of MPs lies on the difficulty of removing these particles from water during wastewater and drinking water treatments. The release of MPs to the environment in treated wastewater contributed to the dispersion of these micropollutants, which enhances the harmful effect of MPs on fauna and flora. In addition, their presence in tap water entails a potential risk to human health since MPs can be directly consumed. The first step is being able to quantify and characterise these microparticles accurately. In this work, a comprehensive analysis on the presence of MPs in wastewater, drinking water and tap water has been conducted with emphasis on sampling methods, pre-treatment, MP size and analytical methods. Based on literature data, a standard experimental procedure has been proposed with the objective of recommending a methodology that allows the homogenisation of MP analysis in water samples. Finally, reported MP concentrations for influents and effluents of drinking and wastewater treatment plants and tap water have been analysed, in terms of abundance, ranges and average values, and a tentative classification of different waters based on their MP concentrations is proposed.
... PET and PA (mainly nylon 6 and nylon 6.6) account for the majority of synthetic MFs produced worldwide at a ratio of approximately 10:1 [48]. Consequently, the largest fraction of synthetic MFs found in municipal sewage sludge are MFs in PET [49][50][51]. However, because the analytical protocols for quantifying MPs in environmental matrices commonly rely on the physical separation of MPs [52,53], followed by their detection by optical microscopy and identification by FT-IR micro-spectroscopies [54] or Raman [55,56], MFs in PAs often go undetected due to their similar spectroscopic characteristics to protein materials [57,58]. ...
Citation: Bianchi, S.; Bartoli, F.; Bruni, C.; Fernandez-Avila, C.; Rodriguez-Turienzo, L.; Mellado-Carretero, J.; Spinelli, D.; Coltelli, M.-B. Opportunities and Limitations in Recycling Fossil Polymers from Textiles. Macromol 2023, 3, 120-148. https://doi.org/ 10.3390/macromol3020009 Academic Editor: Ivo Grabchev Abstract: The recovery and recycling of textile waste is becoming urgent since textiles are generating more and more waste. In one year, about 92 million tons of textile waste are produced and the fashion industry accounts for 58 million tons of plastic waste per year. Several different synthetic fibres are used in textiles, thanks to their excellent processability and mechanical properties, but on the other hand, the difficulties linked to their end of life and the release of microplastics from them during washing is currently a cause of great concern. In this context, policy actions have been aimed at promoting recycling of waste and replacing fossil-based fibres with biobased fibres. The current review, considering both scientific papers published on international journals and web sources, considers the sorting of textiles and the possible recycling of polyesters, polyamides and acrylics. Nevertheless, the contamination and presence of mixed fibres in fabrics is another issue to face for recycling. Methodologies to solve the issue linked to the presence of elastane, present in the stretch fabrics, as well as the possibility of recycling textiles in the non-woven and composite sector are investigated. Moreover, chemical recycling and enzymatic recycling of fossil polymers are also considered. Thanks to the comprehensive scheme of this review, it is possible to deduce that, while the use of biobased materials should rapidly increase in textile applications, the perspective of recycling materials obtained from waste textile into durable and/or high-performance products seems the most promising.
... These particles remain in either the effluent or the sludge [13]. Though only <5% of MPs entering the WWTPs are present in the effluent, it is a significant source of contamination considering the huge volumes of effluents that are released daily into water bodies [19,20,81]. For example, the primary source of MP contamination in the US is from WWTP effluents causing a release of over 4 million MPs per facility per day [15,60,[82][83][84][85][86][87][88][89]. ...
Since the 1950s, plastic production has skyrocketed. Various environmental and human activities are leading to the formation and accumulation of microplastics (MPs) in aquatic and terrestrial ecosystems, causing detrimental effects on water, soil, plants, and living creatures. Wastewater treatment plants (WWTPs) are one of the primary MP management centers meant to check their entry into the natural systems. However, there are considerable limitations in effectively capturing, detecting, and characterizing these MPs in the inlet and outlet of WWTPs leading to “unaccounted MPs” that are eventually discharged into our ecosystems. In order to assess the holistic picture of the MPs’ distribution in the ecosystems, prevent the release of these omitted MPs into the environment, and formulate regulatory policies, it is vital to develop protocols that can be standardized across the globe to accurately detect and account for MPs in different sample types. This review will cover the details of current WWTP adoption procedures for MP management. Specifically, the following aspects are discussed: (i) several processes involved in the workflow of estimating MPs in the outlet of WWTPs; (ii) key limitations or challenges in each process that would increase the uncertainty in accurately estimating MPs; (iii) favorable recommendations that would lead to the standardization of protocols in the workflow and facilitate more accurate analysis of MPs; (iv) research opportunities to tackle the problem of ‘missing MPs’; and (v) future research directions for the efficient management of MPs. Considering the burgeoning research interest in the area of MPs, this work would help early scientists in understanding the current status in the field of MP analysis in the outlet of WWTPs.
... Not only the effluent of WWTPs but also WWTP sludges cause the release of MPs into the environment. In WWTPs, high amounts of MP of different polymer types, different shapes, and sizes are accumulated in the sludge of primary settling tanks, secondary settling tanks, and membrane sludge (Lares et al. 2018;Ren et al. 2020;Pittura et al. 2021). ...
... Millions or more MPs are released into the environment through the disposal of tons of sludge produced in WWTPs or their use as fertilizer on agricultural lands (Magni et al. 2019;Ren et al. 2020;Harley-Nyang et al. 2022). Except for Germany, which states that the plastic content in fertilizers cannot exceed 0.1% by weight (Weithmann et al. 2018) many countries have (Quinn et al. 2017) Lifespan (years) (Mohanan et al. 2020) Application (Barboza et al. 2018;Jones et al. 2020;Plastics Europe 2021) Low-density polyethylene (LDPE) 0.91-0.92 ...
... Magni et al. (2019) reported 113 + 57 MPs/g (dw) MP in the recycled activated sludge of WWTP in Italy and estimated that 3.4 Â 10 9 MPs accumulated per day in the sludge of this plant, from which 30 tons/day of sludge was produced. Ren et al. (2020) reported that the MP concentration in the dewatered and dried sludge in a WWTP of 300,000 m 3 /day in China was 2.92 Â 10 3 MP/kg and 3.15 Â 10 8 MP would be released into the environment from WWTP producing 108 tons of sludge. Similarly, Harley-Nyang et al. (2022) found that 1.61 Â 10 10 and 1.02 Â 10 10 MP would be released into the environment each month, respectively, with the use of anaerobic digested and lime-stabilized sludge of a WWTP in the UK as fertilizer on agricultural land, and they estimated that this was the equivalent of .20,000 ...
Since wastewater treatment plants (WWTPs) cannot completely remove microplastics (MPs) from wastewater, WWTPs are responsible for the release of millions of MPs into the environment even in 1 day. Therefore, knowing the sources, properties, removal efficiencies and removal mechanisms of MPs in WWTPs is of great importance for the management of MPs. In this paper, firstly the sources of MPs in WWTPs and the quantities and properties (polymer type, shape, size, and color) of MPs in influents, effluents, and sludges of WWTPs are presented. Following this, the MP removal efficiency of different treatment units (primary settling, flotation, biological treatment, secondary settling, filtration-based treatment technologies, and coagulation) in WWTPs is discussed. In the next section, details about MP removal mechanisms in critical treatment units (settling and flotation tanks, bioreactors, sand filters, membrane filters, and coagulation units) in WWTPs are given. In the last section, the mechanisms and factors that are effective in adsorbing organic–inorganic pollutants in wastewater to MPs are presented. Finally, the current situation and research gap in these areas are identified and suggestions are provided for topics that need further research in the future.
... Also, those processes are analogous to the ones used in wastewater treatment plants. In this context, their efficiency for MP removal have been demonstrated in many studies (Lv et al., 2019;Alavian Petroody et al., 2020;Ren et al., 2020;Tadsuwan and Babel, 2022). Currently published studies on DWTPs found concentrations varying by several orders of magnitude (Danopoulos et al., 2020). ...
Microplastics (MP) have been detected in almost all matrices, including drinking water, and assessing the contamination of drinking water with this type of pollution is of the utmost sanitary importance. This study aims to evaluate MP contamination of inlet river water and drinking water at three drinking water treatment plants (DWTPs) in the Paris region in France. Each plant performs water treatment processes that are efficient for particulate matter removal such as coagulation-flocculation, sand filtration, and granular activated carbon filtration. One of the plants also has a parallel water treatment file that uses microfiltration and nanofiltration processes. This file was investigated to assess its efficiency compared to the others. To our knowledge, this study is the first to investigate MP contamination in a DWTP using nanofiltration processes. The drinking water distribution network was also investigated, with samples taken at three network points. Microplastics contamination of sizes 25–5,000 μm was characterized using micro-Fourier transform infrared spectroscopy (μ-FTIR) in large volume samples (500 L) with complete mapping of each sample. Concentrations ranging from 7.4 to 45.0 MP/L were found in inlet water while concentrations ranging from blank level (0.003 MP/L) to 0.260 MP/L were found in outlet drinking water (overall removal rate above 99%). Polyethylene, polypropylene, and polyethylene terephthalate were the main polymers found both at the inlet and outlet, but ratios varied significantly at the outlet. No MP were detected in four out of the six samples from the nanofiltration file, and were not found to have significantly different concentrations compared to blank level. Concentrations in the distribution network were higher overall than at the corresponding DWTP outlet, although a high degree of variation between samples was observed. Our results suggest that membrane processes of microfiltration and nanofiltration are more efficient than typical treatment processes, and also that a MP re-contamination within the distribution network itself might occur.
... Virtually 45% of MPs are removed during the pretreatment physical processes; depending on the specific characteristics of the settling tank, primary treatment can achieve different removal efficiencies from 22% to 99%. The total removal rate of MPs in a WWTP in Zhengzhou, China, from the influent to the final effluent was 81.9%, with an abundance of them 16.0 MPs/L and 2.9 MPs/L in the influent water and effluent (Ren et al., 2020). Not only do microplastics play a vital role as a vector of hazardous chemicals on their surfaces but also they are made by hazardous chemical additives during their production to increase polymer properties and prolong their life (Campanale et al., 2020). ...
Microplastic pollution is a serious threat to the biota and humans, and wastewater treatment plants act as a pathway for entering microplastics into the environment. This study discusses the identification and quantification of microplastics in the south of Tehran municipal WWTP. The sampling was repeated three times in a month, overall, nine times for water samples and once a month in total, three times for digested sludge samples by steel bucket with the WPO method. The microplastics from water and digested sludge samples were identified using the micro‐Raman microscope. According to this study, 98.9% of microplastic particles in effluent and 99.2% of microplastics particles in the sludge were fibers. The influent contained an average of 180 ± 4.3 MP/L and was reduced to 5.3 ± 0.31 MP/L in the final effluent. Despite this significant reduction, we calculate that this WWTP releases 2.3 × 10 ⁹ microplastics per day through final effluent and 1.61 × 10 ¹⁰ particles per day through dried sludge into the environment. We performed micro‐Raman analyses and ICP mass to measure the amount of heavy metal absorption of MPs. In addition, SEM analyses were used to study the surface morphology of microplastic particles.
Practitioner Points
Fourteen different polymers were identified in the influent, effluent, and digested sludge.
The main collected shapes obtained were fiber, film, and fragment, which fiber was the predominant polymer in this WWTP.
The plant releases 2.3 * 10 ⁹ MPs per day to its downstream environment.
This WWTP has average removal with an efficiency of 99.06%.
