Special Issue "Analysis and Prevention of Microplastics Pollution in Water: Current Research and Future Directions"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Quality and Contamination".

Deadline for manuscript submissions: closed (15 November 2021) | Viewed by 7719

Special Issue Editor

Prof. Dr. Paolo Tremolada
E-Mail Website
Guest Editor
Department of Environmental Science and Policy (ESP), University of Milan, Milano, Italy
Interests: environmental distribution and modeling of persistent organic pollutants; nanoparticle distribution and effects on aquatic fauna; microplastic distribution in rivers and in drinking water

Special Issue Information

Dear Colleagues,

Microplastics (MPs) are currently found almost everywhere, and the aquatic compartment is the final sink for most of the plastic debris. The marine environment is dramatically impacted by all kind of plastic contamination, and inland waters are also considered an important target of MPs. The detected polymers are mainly those found in common-use products: polyethylene (PE)—mainly in its low-density (LDPE; bin bags, plastic wraps, shopping bags) and high-density (HDPE; shopping bags, bottle caps, detergent bottles) forms, polypropylene (PP; yoghurt packaging, straws, semi-rigid containers), polystyrene (PS; foamed food containers, plastic cutlery), polyvinyl chloride (PVC, pipes), and polyethylene terephthalate (PET; bottles, food trays). Moreover, a wide range of chemical additives (e.g., polybrominated diphenyl ethers, bisphenol A, phthalates, fatty acids) are commonly added to polymers in order to modify their physicochemical properties (such as flame resistance, color, plasticity/viscosity, and lubricity). Other chemicals can be absorbed from the environment by physical partitioning into the polymer matrix (such as lipophilic persistent organic pollutants). Microplastics can reach food products via the food chain or during foodstuff manipulations, leading to direct human exposure. Triggered by the numerous studies on MP occurrence and reinforced by the detection of MPs in human stool, plastic pollution has also become of concern as a potential threat to human health. Recent studies confirmed the presence of MPs in bottled drinking water, but the methodologies used for identifying MPs were very different, highlighting the need for standardization of MP analysis and improvements in quality assurance.

The following diverse scientific issues seem to be of the greatest urgency:

  • Comparative studies on different analytical methodologies for microplastic detection;
  • Microplastic occurrence in inland waterbodies and source quantification;
  • Microplastic effect at cellular, organ, and individual level, mainly regarding “environmental” microplastics;
  • Size and shape effect of microplastic toxicity;
  • Removal efficiencies in wastewater treatment plants;
  • From microplastics to nanoplastics: size scale continuity or different worlds.

Prof. Dr. Paolo Tremolada
Guest Editor

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Keywords

  • Microplastic
  • Nanoplastics
  • Chemical additives
  • Analytical methodologies
  • Removal efficiencies
  • Wastewater treatment plants
  • Microplastic toxicity
  • Cytotoxicity

Published Papers (5 papers)

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Research

Article
The Toxicity of Polyester Fibers in Xenopuslaevis
Water 2021, 13(23), 3446; https://doi.org/10.3390/w13233446 - 04 Dec 2021
Cited by 2 | Viewed by 763
Abstract
Microplastics are practically ubiquitous and pose a serious survival challenge for many species. Most of the exposure experiments for determining the toxicological effects of microplastics were performed with a microplastic varying little in shape and size (often purchased microplastic beads), but few studies [...] Read more.
Microplastics are practically ubiquitous and pose a serious survival challenge for many species. Most of the exposure experiments for determining the toxicological effects of microplastics were performed with a microplastic varying little in shape and size (often purchased microplastic beads), but few studies deal with non-homogeneous samples. We analyzed the effect on Xenopuslaevis larva on the early development of polyester fibers, PEFs, taken from a dryer machine in which 100% polyester fabrics were dried after washing. Three concentrations were tested. The results showed that the gastrointestinal tract, GIT, was the most affected system by PEFs which modified the normal shape of the intestine with an EC50 96 h value of 6.3 µg mL−1. Fibers were observed to press against the digestive epithelium, deforming the normal architecture of the gut, sometimes pushing deep into the epithelium until piercing it. Physical GIT occlusion was observed in a concentration-dependent manner. However, no other damages were registered. No mortality was observed, but PEF-exposed larvae showed a significant reduction in their mobility. The results of the present paper suggest that environmental samples with their heterogeneity may have adverse effects on X. laevis development. Full article
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Article
Are Rural and Small Community Aerated Wastewater Stabilization Ponds a Neglected Source of Microplastic Pollution?
Water 2021, 13(20), 2833; https://doi.org/10.3390/w13202833 - 12 Oct 2021
Viewed by 778
Abstract
Wastewater treatment systems collect and treat sewage that includes microplastics (MPs). However, we are not aware of any studies on the occurrence and distribution of MPs in wastewater stabilization ponds (WSPs), which serve small communities worldwide. Here, we characterized MPs (~45 µm–5 mm) [...] Read more.
Wastewater treatment systems collect and treat sewage that includes microplastics (MPs). However, we are not aware of any studies on the occurrence and distribution of MPs in wastewater stabilization ponds (WSPs), which serve small communities worldwide. Here, we characterized MPs (~45 µm–5 mm) in an aerated WSP serving ~500 houses and an adjacent lake. Putative MPs were most abundant in duckweed (Lemna minor) and sludge (75 ± 22 and 12.8 ± 3.1 particles/g, respectively: ±1 standard deviation (SD), n = 6, dry weight). In the water, average concentrations (particles/L ± 1 SD, n = 6) were highest in the pond (4.1 ± 0.6), followed by effluent (3.9 ± 0.5) and the lake (2.6 ± 0.6). Over 20 types of MPs were identified in each different compartment, with the distribution varying somewhat between the water, sludge, and duckweed. Polyester and polyethylene were the predominant types, followed by polyethylene terephthalate, polyacrylate, polyvinyl chloride, polystyrene, and others. Morphologies consisted of fibers (62–71%), fragments (28–37%), and beads (1–6%). High-density polymers were more frequently found in sludge. Potential sources of the MPs include synthetic textiles from laundry and other plastics washed down household drains. Overall, with ~786,000 MPs/day released in the pond effluent and with duckweed a source of food for waterfowl, we demonstrate that WSPs can be point sources of MPs to both aquatic and terrestrial ecosystems and thus deserve further scrutiny. Full article
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Article
Impact of Chitosan Pretreatment to Reduce Microfibers Released from Synthetic Garments during Laundering
Water 2021, 13(18), 2480; https://doi.org/10.3390/w13182480 - 09 Sep 2021
Cited by 2 | Viewed by 811
Abstract
Sewage treatment can remove more than 90% of microplastics, yet large amounts of microplastics are discharged into the ocean. Because microfibers (MFs), primarily generated from the washing of synthetic clothes, are the most abundant type of microplastics among various microplastics detected in the [...] Read more.
Sewage treatment can remove more than 90% of microplastics, yet large amounts of microplastics are discharged into the ocean. Because microfibers (MFs), primarily generated from the washing of synthetic clothes, are the most abundant type of microplastics among various microplastics detected in the sewage treatment, reducing the amount of MFs entering these treatment plants is necessary. This study aimed to test whether the amount of MFs released from the washing process can be reduced by applying a chitosan pretreatment to the garments before washing. Before the chitosan pretreatment, the polyester clothes released 148 MFs/L, whereas 95% of MFs were reduced after the chitosan pretreatment with 0.7% of chitosan solution. The chitosan pretreatment was applied to other types of garments, such as polyamide and acrylic garments, by treating them with 0.7% of chitosan solution; subsequently, MFs reduced by 48% and 49%, respectively. A morphology analysis conducted after washing revealed that chitosan coating on the polyamide and acrylic were more damaged than on polyester, suggesting that the binding strength of polyamide and acrylic with chitosan was weaker than that of polyester garment. Thus, the results suggested that the chitosan pretreatment might be a promising solution for reducing the amount of MFs generated in the laundering process. Full article
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Article
Modelling Microplastics in the River Thames: Sources, Sinks and Policy Implications
Water 2021, 13(6), 861; https://doi.org/10.3390/w13060861 - 22 Mar 2021
Cited by 8 | Viewed by 3638
Abstract
With widespread, long-term historical use of plastics and the presence of microplastics in a range of new and existing products, there is rising concern about their potential impacts on freshwater ecosystems. Understanding how microplastics are transported and distributed along river systems is key [...] Read more.
With widespread, long-term historical use of plastics and the presence of microplastics in a range of new and existing products, there is rising concern about their potential impacts on freshwater ecosystems. Understanding how microplastics are transported and distributed along river systems is key to assessing impacts. Modelling the main flow dynamics, mixing, sedimentation and resuspension processes is essential for an understanding of the transport processes. We use the new, processed based, dynamic, integrated catchments (INCA) microplastics model and apply this to the whole of the freshwater catchment of the River Thames, UK, to evaluate inputs, loads and concentrations along the river system. Recent data from UK water industry studies on microplastics in effluent discharges and sewage sludge disposal has been utilised to drive the INCA microplastics model. Predicted concentrations and microplastic loads moving along the river system are shown to be significant, with a build-up of concentrations along the river, with increasing deposition on the riverbed. The potential impacts on aquatic ecosystems are evaluated and a review of policy implications is explored. Full article
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Article
Particle Size and Pre-Treatment Effects on Polystyrene Microplastic Settlement in Water: Implications for Environmental Behavior and Ecotoxicological Tests
Water 2020, 12(12), 3436; https://doi.org/10.3390/w12123436 - 08 Dec 2020
Cited by 3 | Viewed by 1072
Abstract
Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. [...] Read more.
Microplastic (MP) particle dispersions used in many recent publications covering adsorption or toxicological studies are not characterized very well. The size distribution of polydisperse dispersions is highly dependent on the agglomeration processes and influences experimental outcomes. Therefore, pre-treatment is a prerequisite for reproducibility. In this study, manual/automated shaking and ultrasonic treatment as different mechanical dispersion techniques were applied for the dispersion of cryomilled polystyrene (PS). Particle numbers and size distribution of dispersions were analyzed by a light extinction particle counter and the dispersion efficiency (ED) as the ratio between calculated volume and theoretical volume of suspended particles was used to compare techniques. PS dispersions (20 mg/L) treated for 90 min in an ultrasonic bath (120 W, 35 kHz) were evenly dispersed with a particle concentration of 140,000 particles/mL and a high reproducibility (rel. SD = 2.1%, n = 6). Automated horizontal shaking for 754 h (250 rpm) reached similar particle numbers (122,000/mL) but with a lower reproducibility (rel. SD = 9.1%, n = 6). Manual shaking by hand dispersed the lowest number of particles (55,000/mL) and was therefore found to be unsuitable to counteract homo-agglomeration. ED was calculated as 127%, 104% and 69% for ultrasonic treatment, horizontal shaking and manual shaking, respectively, showing an overestimation of volume assuming spherical shaped particles. Full article
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