Removal efficiencies of microplastics of the three largest drinking water treatment plants in Bangladesh

Formation mechanisms of carcinogenic N-nitrosamines from dissolved organic matter derived from nitrogen-containing microplastics during chloramine disinfection

The high occurrence of microplastics (MPs) in water treatment facilities may complicate the source-control of disinfection by-products. Herein, we reported that the carcinogenic N-nitrosamines, such as N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), were generated during monochloramine disinfection of water in which nitrogen-containing microplastics (N-MPs, such as polyamide and polyacrylonitrile) were present. The precursors of NDMA and NDEA were mainly derived from the dissolved organic matter released from N-MPs (N-MP-DOM), which were characteristic of a significantly higher proportion of polar and non-cationic fractions, favouring the N-nitrosamine formation. The results of excitation-emission-matrix spectra and orbitrap-mass spectrometry indicated that the polar components were mainly CHON and highly hydrogen-saturated molecules (H/C ≥ 1.5) (such as protein-like substrates), which are potential precursors of N-nitrosamines. Further mass difference network analysis revealed that the reactions of amine and nitro/nitroso groups in the precursors made predominant contribution to the generation of N-nitrosamines. Two potent NDMA precursors bearing a (CH3)2N-R structure were identified based on the diagnostic fragments (e.g., 45.0578 Da and m/z 58.0651) and in silico fragmentation tool (MetFrag 2.2) in MS2 spectra. Our findings provide valuable insights into understanding the potential risks of N-MPs due to monochloramine disinfection in water treatment systems.

Investigation of microplastic pollution index in the urban surface water: A case study in west Godavari district, Andhra Pradesh, India

Microplastics (MPs) are a growing environmental issue because of their widespread prevalence and their long-term effects on ecosystems and human health. Global studies have identified MPs in various aquatic environments, such as lake, rivers, estuaries, wastewater, and oceans. Although most MPs originate from urban surface water sources, the specific intensity, characteristics, and associated risk assessments remain unclear. This study focuses on west Godavari region of India, specifically analyzing MPs in surface water samples Godavari River and two water treatment plants (WTPs). A total of 330 MPs found in the surface water and 121 MPs in theWTP. In surface water, MPs were predominantly blue and transparent fibers, with the majority measuring less than 500 μm in size. Conversely, at the WTP, larger MPs, primarily in blue fiber form and exceeding 3000 μm, were observed. Additionally, μ-Raman spectroscopy analysis identified the presence of various polymers, including PP, PVC, PC, Nylon, and PET, among others. The risks associated with MPs, including their concentration and chemical composition, were assessed across all sample types using various indices such as Contamination Factor (CFi), Pollution Load Index (PLI), Polymer Risk Index (H), Potential Ecological Risk Index (RI), and Estimated Intake (EI) (daily, annually, and lifetime). The risk assessment revealed that the type of polymer poses a greater risk of MP pollution than the concentrations of MPs themselves. These findings provide critical insights into MP contamination patterns and risks, emphasizing the need for targeted mitigation strategies in this region.

First report of a major management target species, chironomid Paratanytarsus grimmii (Diptera: Chironomidae) larvae, in drinking water treatment plants (DWTPs) in South Korea

Ensuring the supply of safe and high-quality drinking water can be compromised by the presence of chironomid larvae in drinking water treatment plants (DWTPs), which may contaminate municipal water systems through freshwater resources. Chironomids are dominant species known for their resilience to a broad range of extreme aquatic environments. This study aimed to identify the morphological characteristics and obtain genetic information of the chironomid Paratanytarsus grimmii found in the water intake source and freshwater resource of DWTPs in Korea, highlighting the potential possibility of a parthenogenetic chironomid outbreak within DWTP networks. The distribution of chironomid larvae at the water intake source site (DY) of the Danyang DWTP and the freshwater resource (ND) of the Nakdong River was investigated. A total of 180 chironomid individuals, encompassing three subfamilies and six species from six 6 genera were identified at the DY site, with Procladius nigriventris being the dominant species. At the ND site, fifty chironomid individuals, encompassing two subfamilies and six species from six genera, were identified, with Cricotopus sylvestris being the dominant species. The morphological characteristics of the head capsule, mentum, mandible, and antennae of six P. grimmii larvae collected from the DY and ND sites were characterized. DNA barcoding and phylogenetic analysis revealed distinct mitochondrial diversities between the P. grimmii larvae from DY and those from ND. These results provide crucial information for the morphological identification and DNA barcoding of the key management target chironomid P. grimmii larvae, which can be used to detect the occurrence of this chironomid species in DWTPs.

Microplastics in the urban water cycle: A critical analysis of issues and of possible (needed?) solutions

Microplastic (MP) contamination is a problem that affects even remote, scarcely populated regions of the world. This topic has recently been the subject of many published studies, however, these often adopt hyperbolic statements and do not actually provide definitive evidence that MPs are a cause of environmental risk in actual environmental conditions. New technologies to remove MPs from supply and waste water are being investigated, but they are able to intercept a minimal fraction of the MPs circulating in all environmental media. Recently, several pieces of legislation were introduced to reduce plastic production, use, and disposal, but it is not clear how such measures could achieve a significant environmental MP reduction. This paper addresses the MP issue within the urban water cycle, examining recent current literature on MP presence in drinking and waste water, and overviewing available recent treatment technologies for their removal. The ensuing discussion attempts to holistically assess the actual relevance of the issue in the light of the current scientific evidence.

Tracking Microplastics Contamination in Drinking Water Supply Chain in Haikou, China: From Source to Household Taps

The presence of microplastics (MPs) in aquatic environments has become a significant global concern due to their potential adverse effects on human health. This study aimed to investigate the contamination of MPs throughout the drinking water supply chain in Haikou City, China, and to conduct risk assessments regarding the relationship between MPs contamination and human health. The results revealed that the abundance of MPs in raw, treated, and tap water was 0.6 ± 0.6, 5.2 ± 2.7, and 1.2 ± 1.1 particles·L-1, respectively. Fragments were identified as the most prevalent shape across all samples, with the size category of 20-50 μm showing the highest abundance of MPs. Among the 11 types of polymers identified, polyethylene and polypropylene accounted for 50% and 29%, respectively. The potential risk index values were significantly higher for treated water (370.26) and tap water (303.85) compared to raw water (13.46), suggesting that plastic pipes may be a key contributor to MPs contamination in drinking water. Therefore, efforts should be directed toward developing pipes with low release rates of MPs, as well as improving detection methods for smaller particles and accurately assessing associated risks.

The hidden threat: Unraveling the impact of microplastics on reproductive health

Microplastics, with intricate physical and chemical characteristics, infiltrate the food chain and extensively impact ecosystems. Despite acknowledging the link between environmental pollution and declining fertility, the specific mechanisms affecting reproductive health remain to be elucidated. This review emphasizes the global correlation between microplastics and subfertility, focusing on entry pathways and impacts on ecosystems. Research suggests that microplastics disrupt the neuroendocrine system, influencing sex hormone synthesis through the hypothalamic-pituitary-gonadal (HPG) axis. In the reproductive system, microplastics interfere with the blood-testis barrier, impairing spermatogenesis in males, and causing placental dysfunction, ovarian atrophy, endometrial hyperplasia, and fibrosis in females. Moreover, microplastics potentially affect offspring's lipid metabolism and reproductive functions. However, complex microplastic compositions and detection method limitations impede research progress. Mitigation strategies for reproductive effects, combined with addressing microplastic pollution through sustainable practices, are imperative. This review underscores the urgency of global initiatives and collaborative research to safeguard reproductive health amid escalating microplastic contamination.

Mapping Microplastics in Humans: Analysis of Polymer Types, and Shapes in Food and Drinking Water-A Systematic Review

Microplastics (MPs) pervade the environment, infiltrating food sources and human bodies, raising concerns about their impact on human health. This review is focused on three key questions: (i) What type of polymers are humans most exposed to? (ii) What are the prevalent shapes of MPs found in food and human samples? (iii) Are the data influenced by the detection limit on the size of particles? Through a systematic literature analysis, we have explored data on polymer types and shapes found in food and human samples. The data provide evidence that polyester is the most commonly detected polymer in humans, followed by polyamide, polyurethane, polypropylene, and polyacrylate. Fibres emerge as the predominant shape across all categories, suggesting potential environmental contamination from the textile industry. Studies in humans and drinking water reported data on small particles, in contrast to larger size MPs detected in environmental research, in particular seafood. Discrepancies in size detection methodologies across different reports were identified, which could impact some of the discussed trends. This study highlights the need for more comprehensive research on the interactions between MPs and biological systems and the effects of MPs on toxicity, together with standardised analytical methodologies to accurately assess contamination levels and human exposure. Understanding these dynamics is essential for formulating effective strategies to mitigate the environmental and health implications of MP pollution.

Microplastics attenuation from surface water to drinking water: Impact of treatment and managed aquifer recharge - and identification uncertainties

River water can be used to recharge aquifers exploited for drinking water production. Several recent studies reported microplastics (MPs) in river water, and therefore, the potential contamination of groundwater by MPs is a growing concern among stakeholders and citizens. In this research, we investigate the fate of MPs (> 20 μm) along six different stages of a major Managed Aquifer Recharge (MAR)-water supply system in Switzerland. About 20 l of water were filtered using steel meshes at each location in triplicates. In the laboratory, MPs deposited on the anodisc filters were identified using Focal Plane Array (FPA) micro-Fourier-Transform-InfraRed (μFTIR) spectroscopy. The obtained hyperspectral data were processed using the imaging software Microplastics Finder for MPs identification and classification. Our results revealed a 20-fold decrease in MPs concentration from the Rhine River bed water (112 ± 27.4 MPs/l) to after the coagulation, flocculation and sedimentation (5.5 ± 2.2 MPs/l), a further 3-fold decrease to after the sand-filtration system (1.8 ± 0.9 MPs/l), corresponding to an overall removal efficiency of 98.4 %. The MPs concentrations remained low following MAR (2.7 ± 0.7 MPs/l) through a Quaternary gravel aquifer. Activated carbon filters did not substantially further reduce MPs concentrations. The percentage of fragments (≈95 %) prevailed over fibers (≈5 %) at all locations, with fibers being longer and more abundant in the river water. Overall, this study demonstrates the effectiveness of the treatment systems to remove MPs larger than 20 μm. Finally, we calculated an uncertainty in MPs concentrations of one order of magnitude depending on the user-defined parameters inside the MPs identification and classification model. The Quality Assurance/Quality Control approach followed during laboratory analysis highlighted an accumulation of surrogate particles at the edges of the disc, which would have an impact for MPs number upscaling.

Investigating biodegradation of polyethylene and polypropylene microplastics in Tehran DWTPs

Microplastic (MP) pollution is a growing concern and various methods are being sought to alleviate the level of pollution worldwide. This study investigates the biodegradation capacity of MPs by indigenous microorganisms of raw water from Tehran drinking water treatment plants. By exposing polypropylene (PP) and polyethylene (PE) MPs to selected microbial colonies, structural, morphological, and chemical changes were detected by scanning electron microscope (SEM), cell weight measurement, Fourier transform infrared (FTIR), Raman spectroscopy test, and thermal gravimetric analysis (TGA). Selected bacterial strains include Pseudomonas protegens strain (A), Bacillus cereus strain (B), and Pseudomonas protegens strain (C). SEM analysis showed roughness and cracks on PP MPs exposed to strains A and C. However, PE MPs exposed to strain B faced limited degradation. In samples related to strain A, the Raman spectrum was completely changed, and a new chemical structure was created. Both TGA and FTIR analysis confirmed changes detected by Raman analysis of PP and PE MPs in chemical changes in this study. The results of cell dry weight loss for microbial strains A, B, and C were 13.5, 38.6, and 25.6%, respectively. Moreover, MPs weight loss was recorded at 32.6% for PP MPs with strain A, 13.3% for PE MPs with strain B, and 25.6% for PP MPs with strain C.