An audit of microplastic abundance throughout three Australian wastewater treatment plants

Microfiber pollution: Assessment, emission estimation, and time-series-based forecast of microfibers from domestic washing machine laundering and mitigation measures

Microfibers are thread-like structures shorter than 5 mm and have natural, semisynthetic, or synthetic origins. These micropollutants are ubiquitous and are emerging in the environment, living organisms, and food sources. Textile laundering is a prominent source of microfibers, but limited research has been conducted on microfiber pollution from domestic washing machines in emerging economies such as India, where consumption and production rates are exorbitantly high. This study aimed to assess the abundance and size distribution of microfibers from the effluent of a semiautomatic domestic washing machine using three categories of "not-new" textiles: cotton, blended, and synthetic under "with" and "without" detergent conditions. Although most Indians still rely on hand washing, this study focused on washing machines due to their increasing use in India driven by improving socioeconomic factors. This study also developed annual emission estimation and forecasting models for India to understand pollution trends. The results revealed that microfibers were highly abundant in washing machine effluent, with a mean abundance of cotton, blended, and synthetic in "with detergent" conditions of 6476.67, 3766.67, and 8645/L, respectively, whereas in "without detergent," it was lower. All identified microfibers were divided into five size classes. The study also found that powdered detergent increased the abundance and emission of tiny fibers. The overall annual emissions estimate was 1.23 × 1011 microfibers, with cotton, synthetic, and blended categories accounting for 2.11 × 1010, 1.40 × 1010, and 6.15 × 109 microfibers, respectively. Time-series-based future estimates (autoregressive integrated moving average [ARIMA] and error-trend-seasonality [ETS]) showed an alarming increase in microfiber emissions, with forecasted annual emission reaching 1.90 × 1011 by 2030. Synthetic and cotton textiles are the most significant contributors to microfiber pollution. This study emphasized the urgent need to address the issue of microfiber pollution caused by washing machine laundering in developing countries, such as India, where sociodemographic factors intensify the problem. Integr Environ Assess Manag 2024;20:2116-2127. © 2024 SETAC.

Taxonomic variation, plastic degradation, and antibiotic resistance traits of plastisphere communities in the maturation pond of a wastewater treatment plant

Wastewater treatment facilities can filter out some plastics before they reach the open environment, yet microplastics often persist throughout these systems. As they age, microplastics in wastewater may both leach and sorb pollutants and fragment to provide an increased surface area for bacterial attachment and conjugation, possibly impacting antimicrobial resistance (AMR) traits. Despite this, little is known about the effects of persistent plastic pollution on microbial functioning. To address this knowledge gap, we deployed five different artificially weathered plastic types and a glass control into the final maturation pond of a municipal wastewater treatment plant in Ōtautahi-Christchurch, Aotearoa/New Zealand. We sampled the plastic-associated biofilms (plastisphere) at 2, 6, 26, and 52 weeks, along with the ambient pond water, at three different depths (20, 40, and 60 cm from the pond water surface). We investigated the changes in plastisphere microbial diversity and functional potential through metagenomic sequencing. Bacterial 16S ribosomal RNA genes composition did not vary among plastic types and glass controls (P = 0.997) but varied among sampling times [permutational multivariate analysis of variance (PERMANOVA), P = 0.001] and depths (PERMANOVA, P = 0.011). Overall, there was no polymer-substrate specificity evident in the total composition of genes (PERMANOVA, P = 0.67), but sampling time (PERMANOVA, P = 0.002) and depth were significant factors (PERMANOVA, P = 0.001). The plastisphere housed diverse AMR gene families, potentially influenced by biofilm-meditated conjugation. The plastisphere also harbored an increased abundance of genes associated with the biodegradation of nylon, or nylon-associated substances, including nylon oligomer-degrading enzymes and hydrolases.IMPORTANCEPlastic pollution is pervasive and ubiquitous. Occurrences of plastics causing entanglement or ingestion, the leaching of toxic additives and persistent organic pollutants from environmental plastics, and their consequences for marine macrofauna are widely reported. However, little is known about the effects of persistent plastic pollution on microbial functioning. Shotgun metagenomics sequencing provides us with the necessary tools to examine broad-scale community functioning to further investigate how plastics influence microbial communities. This study provides insight into the functional consequence of continued exposure to waste plastic by comparing the prokaryotic functional potential of biofilms on five types of plastic [linear low-density polyethylene (LLDPE), nylon-6, polyethylene terephthalate, polylactic acid, and oxygen-degradable LLDPE], glass, and ambient pond water over 12 months and at different depths (20, 40, and 60 cm) within a tertiary maturation pond of a municipal wastewater treatment plant.

Microplastics are effective carriers of bisphenol A and facilitate its escape from wastewater treatment systems

Microplastics (MPs) pollution is a major issue in aquatic environments. Wastewater treatment plants are significant point sources of MPs, which may also be carriers of organic pollutants. We analyzed MP number, shape, color, and polymer type distribution in sewage wastewater treatment plants. The potential of MPs to act as carriers for typical organic pollutants in sewage, such as bisphenol A (BPA), was also assessed. The predominant MPs in the influent were fibers, primarily transparent and black in color, and composed of polyethylene, polypropylene, and polystyrene. During wastewater treatment, the concentration of MPs decreased from 10.89 items per L in the influent to 0.89 items per L in the treated effluent, with significant differences in treatment efficiency at different stages. In the simulated wastewater, the three predominant MPs exhibited certain adsorption capacities for bisphenol A. Changing the temperature and pH within the range expected for wastewater could interfere with the interactions between MPs and bisphenol A, with a limited impact on adsorption. The results show that although wastewater treatment plants intercept a significant amount of MP, a considerable number of them enter the aquatic environment daily because of the high volume of wastewater discharge. These MPs, which carry pollutants such as bisphenol A, may threaten the health of fish and other aquatic organisms. However, by scientifically adjusting operational parameters, wastewater treatment plants could become "controllable sources" of MP compound pollutants.

Accumulation of persistent organic pollutants by MPs in coastal wastewater treatment plants

The abundance and fate of microplastics (MPs) in wastewater treatment plants (WTPs) has been reported extensively. However, in the wastewater, the extent to which hazardous chemicals such as persistent organic pollutants (POPs) accumulated by MPs not been clearly explored. In this study, MPs was sampled from influents and effluents in WTPs to characterize POPs in sorption within MPs. The highest concentrations of PCDD/Fs, PBDD/Fs, PBDEs, and PCBs in sorption within MPs from untreated influents were 5310, 2310, 5,220,000, and 22,700 pg/g, respectively. The most toxic congener, 1,2,3,7,8-PeCDD, accounts for up to 32.3 % of the contribution to PCDD/Fs within MPs. Furthermore, the concentration of PCDD/Fs within MPs from untreated influents could be up to 27.7 times higher than that in microplastic pellets on the coastal beach. This study highlights the quantitative evidence of the POPs within MPs present in untreated influents.

The crucial factor for microplastics removal in large-scale subsurface-flow constructed wetlands

Constructed wetlands (CWs) are an effective method for removing microplastics (MPs). Nevertheless, the understanding of the impact of various parameters on MPs removal within CWs remains incomplete. Through field investigations of large-scale CWs and the application of machine learning methods with an interpretable attribution technique (the Shapley Additive Explanation), we investigated the critical factors influencing MPs removal within CWs. The MPs abundance in the influent and the inlet of Z-CW (400.1 ± 20.8 items/L and 699.6 ± 50.6 items/kg) was significantly higher compared to that in M-CW (138.8 ± 20.5 items/L and 166.5 ± 36.8 items/kg), with no significant difference observed in the effluent. The primary characteristic of MPs is their fibrous and transparent appearance. The MPs removal range from 87.9% to 95.5 %, influenced by the types and characteristics of MPs, physical and chemical parameters, biofilms, and different processes. Among these factors, dissolved organic carbon with high humic content, aromaticity, and carboxyl abundance may serve as a crucial factor in MPs removal. The results of this study highlight the significance of physical and chemical parameters for the MPs removal in CWs, providing the necessary theoretical data for the construction of future large-scale engineering applications.

Transport and Accumulation of Microplastics from Biosolids to Australian Agricultural Soils: Detection of Microplastics Down to 1 μm

The shift toward sustainable agriculture involves replacing inorganic fertilizers with organic alternatives like biosolids. However, concerns arise over emerging contaminants, such as microplastics (MPs), which remain largely unregulated. Despite their common use in Australia, the transfer of MPs from biosolids to agricultural soils remains largely unknown. Herein, we have investigated the abundance, characteristics, and transport of MPs resulting from biosolids application in two Queensland agricultural sites. MP concentrations were significantly higher in biosolid-amended soils (average of 1137 MPs/kg) than in reference sites (average of 36 MPs/kg), correlating with the volume, time since application, and frequency of biosolids application. MPs > 25 μm were predominantly polyethylene, polypropylene, and poly(methyl methacrylate) fragments (up to 85%). Fibers constitute only 15-30% of MPs and mainly in larger sizes (average 1011 μm), whereas fragments (average 188 μm) and beads (average 72 μm) had smaller size ranges. Despite analytical challenges using Raman spectroscopy, detected smaller MPs (1-25 μm) were fragments composed of polyethylene, polypropylene, and poly(vinyl alcohol). This study provides the first report of MPs down to 1 μm in Australian agricultural soils. Our findings suggest a need to assess the long-term impact of MPs in biosolids on soil health and food safety. We call on policymakers to consider the implementation of effective MP source control strategies and the development of guidelines for acceptable biosolids application rates.

Factors influencing the distribution, risk, and transport of microplastics and heavy metals for wildlife and habitats in "island" landscapes: From source to sink

Microplastics (MPs) and heavy metals (HMs) are important pollutants in terrestrial ecosystems. In particular, the "island" landscape's weak resistance makes it vulnerable to pollution. However, there is a lack of research on MPs and HMs in island landscapes. Therefore, we used Helan Mountain as the research area. Assess the concentrations, spatial distribution, ecological risks, sources, and transport of MPs and HMs in the soil and blue sheep (Pseudois nayaur) feces. Variations in geographical distribution showed a connection between human activity and pollutants. Risk assessment indicated soil and wildlife were influenced by long-term pollutant polarization and multi-element inclusion (Igeo, Class I; PHI, Class V; RI (MPs), 33 % Class II, and 17 % Class IV; HI = 452.08). Source apportionment showed that tourism and coal combustion were the primary sources of pollutants. Meanwhile, a new coupling model of PMF/Risk was applied to quantify the source contribution of various risk types indicated transportation roads and tourism sources were the main sources of ecological and health risks, respectively. Improve the traceability of pollution source risks. Furthermore, also developed a novel tracing model for pollutant transportation, revealing a unique "source-sink-source" cycle in pollutant transportation, which provides a new methodological framework for the division of pollution risk areas in nature reserves and the evaluation of spatial transport between sources and sinks. Overall, this study establishes a foundational framework for conducting comprehensive risk assessments and formulating strategies for pollution control and management.

Traversing the prevalence of microplastics in soil-agro ecosystems: Origin, occurrence, and pollutants synergies

The ubiquity of plastics in modern life has made them a significant environmental concern and a marker of the Anthropocene era. The degradation of plastics results in the formation of microplastics (MPs), which measure 5 mm or less. The coexistence of MPs with other pollutants found in sludge, water treatment plant effluents, surface water, and groundwater, shapes the environmental landscape together. Despite extensive investigation, the long-term implications of MPs in soils remain uncertain, underscoring the importance of delving into their transportation and interactions with soil biota and other contaminants. The present article provides a comprehensive overview of MPs contamination in soil, encompassing its sources, prevalence, features, and interactions with soil flora and fauna, heavy metals, and organic compounds. The sources of MPs in soil agroecosystems are mulching, composting, littering, sewage sludge, irrigation water, and fertilizer application. The concentration of MPs reported in plastic mulch, littering, and sewage sludge is 503 ± 2760 items per kg-1, 4483 ± 2315 MPs/kg, and 11,100 ± 570 per/kg. The transport of MPs in soil agroecosystems is due to their horizontal and vertical migration including biotic and abiotic mobility. The article also highlighted the analytical process, which includes sampling planning, collection, purification, extraction, and identification techniques of MPs in soil agroecosystems. The mechanism in the interaction of MPs and organic pollutants includes surface adsorption or adhesion cation bridging, hydrogen bonding, charge transfer, ligand exchange, van der Waals interactions, and ion exchange.

The significant impact of MPs in the industrial/municipal effluents on the MPs abundance in the Nakdong River, South Korea

Owing to extensive plastic consumption, wastewater from households, business establishments, and industrial activities have been recognised as a significant contributor to microplastics (MPs) in aquatic environments. This case study represents the first investigation of MPs in the Nakdong River, Republic of Korea, that traverses through the largest industrial complex midstream and densely populated cities of Daegu and Busan downstream before flowing into the sea. Monitoring of MP abundance in effluents discharged from three municipal, two industrial, and one livestock wastewater treatment plant (WWTP) into the Nakdong River was conducted over four seasons from August 2022 to April 2023. Identification and quantification of MPs were performed using micro-Fourier transform infrared spectrometry. Seasonal variation in MPs in the Nakdong River was found to be strongly influenced by the nearest upstream WWTPs and rivers, exhibiting a linear relationship that decreased gradually with increasing distance from the WWTPs. The average concentrations of MPs in the six effluent sources ranged from 101 ± 13 to 490 ± 240 particles/L during the yearly monitoring period, while MP concentrations in the river ranged between 79 ± 25 and 120 ± 43 particles/L. Industrial effluents contained higher amounts of discharged MPs (314 ± 78 particles/L) than municipal sources (201 ± 61 particles/L). Notably, two municipal WWTPs, located in the highly densely populated city, discharged the highest total MP amounts per day and released the greatest volumes of effluents. This study provides valuable insights into the monitoring and impact of effluents on MPs in rivers, which could inform MP treatment and management strategies for in river and marine environments.

Deficit irrigation of reclaimed water relieves oat drought stress while controlling the risk of PAEs pollution in microplastics-polluted soil

Reclaimed water irrigation has emerged as a critical alternative in agricultural regions facing water scarcity. However, soil pollution with microplastics (MPs) greatly increases the exposure risk and toxic effects of reclaimed water contaminations, such as phthalate esters (PAEs). A field experiment consisting of soil column pots evaluated the feasibility of using PAEs-contaminated water to irrigate oats (Avena sativa L.) in drought seasons. Three irrigation regimens based on soil matric potential thresholds (-10 kPa, -30 kPa, -50 kPa) explored the impact of PAE-contaminated water on oat physiology and environmental pollution in soil with and without MPs contamination. The results showed that treating oats at the SMP of -30 kPa boosted shoot biomass by 3.1%-14.0% compared to the drought condition at -50 kPa, and the root biomass of oats was significantly increased. The physiological metrics of oats indicated that irrigation at -50 kPa induced drought stress and oxidative damage in oats, particularly during the milk stage. Different irrigation treatments influenced the accumulation of PAEs in plants, soil, and leachate. The ratios of leachate to irrigation water in -10 kPa treatment with and without MPs addition were 1.18% and 4.48%, respectively, which aggravated the accumulation of pollutants in deep soil layers and may cause groundwater pollution. MPs pollution in soil increased the content of PAEs in the harvested oats and reduced the transport and accumulation of PAEs in deep soil layers (20-50 cm) and leachate. The coupling of PAEs in irrigation water with soil MPs pollution may exacerbate plant damage. However, the damage can be minimized under the scheduled irrigation at -30 kPa which could balance crop yield and potential risks.

Microplastics in aquatic systems: An in-depth review of current and potential water treatment processes

Plastic products, despite their undeniable utility in modern life, pose significant environmental challenges, particularly when it comes to recycling. A crucial concern is the pervasive introduction of microplastics (MPs) into aquatic ecosystems, with deleterious effects on marine organisms. This review presents a detailed examination of the methodologies developed for MPs removal in water treatment systems. Initially, investigating the most common types of MPs in wastewater, subsequently presenting methodologies for their precise identification and quantification in aquatic environments. Instruments such as scanning electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, Raman spectroscopy, surface-enhanced Raman spectroscopy, and Raman tweezers stand out as powerful tools for studying MPs. The discussion then transitions to the exploration of both existing and emergent techniques for MPs removal in wastewater treatment plants and drinking water treatment plants. This includes a description of the core mechanisms that drive these techniques, with an emphasis on the latest research developments in MPs degradation. Present MPs removal methodologies, ranging from physical separation to chemical and biological adsorption and degradation, offer varied advantages and constraints. Addressing the MPs contamination problem in its entirety remains a significant challenge. In conclusion, the review offers a succinct overview of each technique and forwards recommendations for future research, highlighting the pressing nature of this environmental dilemma.

Research priorities on microplastics in marine and coastal environments: An Australian perspective to advance global action

Plastic and microplastic contamination in the environment receive global attention, with calls for the synthesis of scientific evidence to inform actionable strategies and policy-relevant practices. We provide a systematic literature review on microplastic research across Australian coastal environments in water, sediment and biota, highlighting the main research foci and gaps in information. At the same time, we conducted surveys and workshops to gather expert opinions from multiple stakeholders (including researchers, industry, and government) to identify critical research directions to meet stakeholder needs across sectors. Through this consultation and engagement process, we created a platform for knowledge exchange and identified three major priorities to support evidence-based policy, regulation, and management. These include a need for (i) method harmonisation in microplastic assessments, (ii) information on the presence, sources, and pathways of plastic pollution, and (iii) advancing our understanding of the risk of harm to individuals and ecosystems.

Microplastics removal in wastewater treatment plants: A review of the different approaches to limit their release in the environment

In last 10 years, the interest about the presence of microplastics (MPs) in the environment has strongly grown. Wastewaters function as a carrier for MPs contamination from source to the aquatic environment, so the knowledge of the fate of this emerging contaminant in wastewater treatment plants (WWTPs) is a priority. This work aims to review the presence of MPs in the influent wastewater (WW) and the effectiveness of the treatments of conventional WWTPs. Moreover, the negative impacts of MPs on the management of the processes have been also discussed. The work also focuses on the possible approaches to tackle MPs contamination enhancing the effectiveness of the WWTPs. Based on literature results, despite WWTPs are not designed for MPs removal from WW, they can effectively remove the MPs (up to 99 % in some references). Nevertheless, they normally act as "hotspots" of MPs contamination considering the remaining concentration of MPs in WWTPs' effluents can be several orders of magnitude higher than receiving waters. Moreover, MPs removed from WW are concentrated in sewage sludge (potentially >65 % of MPs entering the WWTP) posing a concern in case of the potential reuse as a soil improver. This work aims to present a paradigm shift intending WWTPs as key barriers for environmental protection. Approaches for increasing effectiveness against MPs have been discussed in order to define the optimal point(s) of the WWTP in which these technologies should be located. The need of a future legislation about MPs in water and sludge is discussed.

Treating wastewater for microplastics to a level on par with nearby marine waters

Retention of microplastics (MPs) at the third largest wastewater treatment plant (WWTP) in Sweden was investigated. The plant is one of the most modern and advanced of its kind, with rapid sand filter for tertiary treatment in combination with mechanical, biological, and chemical treatment. It achieved a significantly high treatment efficiency, which brought the MP concentration in its discharge on par with concentrations measured in marine waters of the same region. This novel data shows that properly designed modern WWTPs can reduce the MP content of sewage down to background levels measured in the receiving aquatic environment. Opposite to current understanding of the retention of MP by WWTPs, a modern and well-designed WWTP does not have to be a significant point source for MP. MPs were quantified at all major treatment steps, including digester inlet and outlet sludge. MPs sized 10-500 µm were analyzed by a focal plane array based micro-Fourier transform infrared (FPA-µFTIR) microscopy, a hyperspectral imaging technique, while MPs above 500 µm were analyzed by Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Mass was estimated from the hyperspectral images for MPs <500 µm and from microscope images >500 µm. The overall treatment efficiency was in terms of MP counts 99.98 %, with a daily input of 6.42 × 1010 and output of 1.04 × 107 particles. The mass removal efficiency was 99.99 %. The mechanical part of the treatment, the pre-treatment, and primary stages, reduced both the MP counts and mass by approximately 71 %. The combined biological treatment, secondary settling, and final polishing with rapid sand filtration removed nearly all the remaining 29 %. MPs became successively smaller as they passed the different treatment steps. The digester inlet received 1.04 × 1011 MPs daily, while it discharged 9.96 × 1010 MPs, causing a small but not significant decrease in MP counts, with a corresponding MP mass reduction of 9.56 %.

A method for the extraction of microplastics from solid biowastes including biosolids, compost, and soil for analysis by µ-FTIR

Few methods exist detailing the extraction of microplastics from organic matrices. A validated method for the successful extraction of microplastics from solid biowastes including biosolids, compost, and soil for spectroscopic analysis by micro-Fourier transform infrared spectroscopy (µ-FTIR) was developed. Solid dry biowastes were first digested with a wet peroxide oxidation (WPO) with iron (II) solution and 30% hydrogen peroxide followed by sequential density separations with ultra-pure water and 1.8 g cm-3 NaI in an optimised sediment-microplastic isolation (SMI) unit. The average recoveries for spiked microplastics were 92, 95 and 98% for bagged compost, biosolids, and soil, respectively. This method ensures a high microplastic recovery by first chemically disintegrating biowaste aggregates without employing destructive methods like milling and allows for successful density separations where the settled fraction is isolated off from the supernatant, allowing thorough rinsing of the equipment and thus a greater transferal of particles into the vacuum filtering device. Minimal processing steps reduce the instance of introducing contamination and particle loss.•Digestion as a first step to disintegrate aggregates to release entrapped microplastics•Density separation with SMI unit with the method adapted for biowastes•Minimal steps to reduce contamination and particle loss.

Plastics in biogenic matrices intended for reuse in agriculture and the potential contribution to soil accumulation

The spread of biogenic matrices for agricultural purposes can lead to plastic input into soils, raising a question on possible consequences for the environment. Nonetheless, the current knowledge concerning the presence of plastics in biogenic matrices is very poor. Therefore, the objective of the present study was a quali-quantitative characterization of plastics in different matrices reused in agriculture as manures, digestate, compost and sewage sludges. Plastics were quantified and characterized using a Fourier Transform Infrared Spectroscopy coupled with an optical microscope (μFT-IR) in Attenuated Total Reflectance mode. Our study showed the presence of plastics in all the investigated samples, albeit with differences in the content among the matrices. We measured a lower presence in animal matrices (0.06-0.08 plastics/g wet weight w.w.), while 3.14-5.07 plastics/g w.w. were measured in sewage sludges. Fibres were the prevalent shape and plastic debris were mostly in the micrometric size. The most abundant polymers were polyester (PEST), polypropylene (PP) and polyethylene (PE). The worst case was observed in the compost sample, where 986 plastics/g w.w. were detected. The majority of these plastics were compostable and biodegradable, with only 8% consisting of fragments of PEST and PE. Our results highlighted the need to thoroughly evaluate the contribution of reused matrices in agriculture to the plastic accumulation in the soil system.

Snapshot Sampling May Not Be Enough to Obtain Robust Estimates for Riverine Microplastic Loads

Wastewater treatment plants (WWTPs) have been described as key contributors of microplastics (MPs) to aquatic systems, yet temporal fluctuations in MP concentrations and loads downstream are underexplored. This study investigated how different sampling frequencies (hourly, weekly, and monthly) affect MP estimates in a stream linked to a single WWTP. Utilizing fluorescence microscopy and Raman spectroscopy, considerable hourly variations in MP concentrations were discovered, while the polymer composition remained consistent. This temporal variability in MP loads was influenced by MP concentration, discharge rates, or a mix of both. These results show a high uncertainty, as relying on sparse snapshot samples combined with annual discharge data led to significant uncertainties in MP load estimates (over- and/or underestimation of emissions by 3.8 billion MPs annually at this site). Our findings stress the necessity of higher-frequency sampling for better comprehending the hydrodynamic factors influencing MP transport. This improved understanding enables a more accurate quantification of MP dynamics, crucial for downstream impact assessments. Therefore, preliminary reconnaissance campaigns are essential for designing extended, representative site-monitoring programs and ensuring more precise trend predictions on a larger scale.

Mass quantification of nanoplastics at wastewater treatment plants by pyrolysis-gas chromatography-mass spectrometry

Municipal wastewater treatment plants (WWTPs) play a crucial role in the collection and redistribution of plastic particles from both households and industries, contributing to their presence in the environment. Previous studies investigating the levels of plastics in WWTPs, and their removal rates have primarily focused on polymer type, size, shape, colour, and particle count, while comprehensive understanding of the mass concentration of plastic particles, particularly those <1 µm (nanoplastics), remains unclear and lacking. In this study, pyrolysis gas chromatography-mass spectrometry was used to simultaneously determine the mass concentration of nine selected polymers (i.e., polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(ethylene terephthalate) (PET), nylon 6, nylon 66, polyvinylchloride (PVC), poly(methyl methacrylate) (PMMA) and polycarbonate (PC)) below 1 µm in size across the treatment processes or stages of three WWTPs in Australia. All the targeted nanoplastics were detected at concentrations between 0.04 and 7.3 µg/L. Nylon 66 (0.2-7.3 µg/L), PE (0.1-6.6 µg/L), PP (0.1-4.5 µg/L), Nylon 6 (0.1-3.6 µg/L) and PET (0.1-2.2 µg/L), were the predominant polymers in the samples. The mass concentration of the total nanoplastics decreased from 27.7, 18 and 9.1 µg/L in the influent to 1, 1.4 and 0.8 µg/L in the effluent, with approximate removal rates of 96 %, 92 % and 91 % in plants A, B and C, respectively. Based on annual wastewater effluent discharge, it is estimated that approximately 24, 2 and 0.7 kg of nanoplastics are released into the environment per year for WWTPs A, B and C, respectively. This study investigated the mass concentrations and removal rates of nanoplastics with a size range of 0.01-1 µm in wastewater, providing important insight into the pollution levels and distribution patterns of nanoplastics in Australian WWTPs.

Spatial and temporal trends of microplastic contamination in surface sediment of Benoa Bay: An urban estuary in Bali-Indonesia

This study aims to explore microplastic contamination in the sediments of Benoa Bay. Eight locations were sampled, with four duplications denoting the rainy and dry seasons. Based on observations, the microplastic concentration varied from 9.51 to 90.60 particles/kg with an average of 31.08 ± 21.53 particles/kg. The area near the landfill had the highest abundance, while the inlet and center of Benoa Bay and the Sama River had the lowest concentration. The fragments (52.2 %) and large microplastic sizes (64.7 %) were the most documented particles. We also identified 17 polymers, which dominated (37.5 %) by polyethylene, polypropylene, and polystyrene. There were no appreciable variations in abundance between seasons, although there were substantial variations in shape and size. Comprehensive investigation, adequate policies, continuous monitoring, and reducing waste from land- and sea-based sources that engage various stakeholders must be implemented urgently to prevent the release of microplastic into the aquatic ecosystem.

The critical role of microplastics in the fate and transformation of sulfamethoxazole and antibiotic resistance genes within vertical subsurface-flow constructed wetlands

Constructed wetlands (CWs) are reservoirs of microplastics (MPs) in the environment. However, knowledge about the impact of MPs on antibiotic removal and the fate of antibiotic resistance genes (ARGs) is limited. We focused on sulfamethoxazole (SMX) as a representative compound to examine the effects of MPs on SMX removal and the proliferation and dissemination of two SMX-related ARGs (sul1 and sul2) in vertical subsurface-flow CW (VFCW) microcosm. The presence of MPs in the substrate was found to enhance the proliferation of microorganisms owing to the large specific surface area of the MPs and the release of dissolved organic carbon (DOC) on MP surfaces, which resulted in a high SMX removal ranging from 97.80 % to 99.80 %. However, the presence of MPs promoted microbial interactions and the horizontal gene transfer (HGT) of ARGs, which led to a significant increase in the abundances of sul1 and sul2 of 68.47 % and 17.20 %, respectively. It is thus imperative to implement rigorous monitoring strategies for MPs to mitigate their potential ecological hazards.

Tracing the origins of plastics in biosolids: The role of sewerage pipe materials and trade waste

Plastics are ubiquitous in virtually every environment on earth. While the specific sources of plastics entering wastewater are not well known, growing evidence suggests sewage sludge (biosolids) can be a sink for plastics. One potential source could be the sewerage pipe materials used to transport sewage between premises and wastewater treatment plants (WWTPs). To evaluate the significance of sewerage piping as a source of biosolids plastics concentrations, we compared the proportion of the total network (by length and surface area) of polyethylene (PE), polyvinylchloride (PVC), and polypropylene (PP) pipes from 10 WWTPs against their biosolids mass concentrations (mg plastic/g biosolid). Among the 10 catchments, the percentage of the network consisting of PP piping ranged from 0 to 1 %, with 0.8-21 % for PE, and 8-73 % for PVC. Biosolids plastics concentrations ranged from 0.09 to 8.62 mg/g (mg plastic/g biosolid) for PP and PE, respectively. For all three plastics, there was no significant Pearson correlation (r < 0.4) between the biosolids concentration (dry weight mg/g) and the proportion of the network material of the sewerage piping as plastic (either length or surface area). A comparison of trade waste entering a subset of 6 WWTP showed the highest biosolid principal components analysis (PCA) associations between loads of plastics (g/day) and automotive wash bays, general manufacturing, hospitals, laboratories, food manufacturing, laundry and dry cleaning, and cooling towers. A stepwise regression analysis indicated pipe length and surface area, as well as automotive wash bays and food manufacturing may be significant. While our data gave mixed results on the attribution of the sources of plastics entering WWTPs, it suggests that sewerage infrastructure and trade waste may play some role. Future studies should investigate the leachability of sewerage infrastructure and contributions from specific trade waste categories to determine their significance in plastics entering WWTPs.

Filtration of polystyrene nanoplastics with different functional groups by natural mineral materials: Performance and mechanisms

Optimizing nanoplastics (NPs) removal performance of rapid sand filter (RSF) in water treatment plants is significant for NP pollution prevention and remediation. This study investigated the application prospect of natural granular manganese sand, zeolite and limestone in RSF for NP removal through column experiments. Pristine, amino-modified, and carboxyl-modified polystyrene NPs (100 nm) were selected as experimental subjects. Quartz sand filter showed negligible NP removal, zeolite and manganese sand showed no obvious optimization on NP filtration. Limestone amended RSF significantly enhanced the removal of three NPs, the removal efficiency increased with decreasing size and increasing limestone grains dosage. The excellent performance of limestone was attributed to its special physicochemical properties in terms of synthetical action of electrostatic interaction, cationic bridging and especially the surface roughness morphology, and the mechanisms overcame the influence of functional groups of NPs. The results indicate the prospective applications of granular limestone in RSF for NP filtration.

Micro/nanoplastics: Critical review of their impacts on plants, interactions with other contaminants (antibiotics, heavy metals, and polycyclic aromatic hydrocarbons), and management strategies

Microplastic/nanoplastics (MPs/NPs) contamination is not only emerging threat to the agricultural system but also constitute global hazard to the environment worldwide. Recent review articles have addressed the environmental distribution of MPs/NPs and their single-exposure phytotoxicity in various plant species. However, the mechanisms of MPs/NPs-induced phytotoxicity in conjunction with that of other contaminants remain unknown, and there is a need for strategies to ameliorate such phytotoxicity. To address this, we comprehensively review the sources of MPs/NPs, their uptake by and effects on various plant species, and their phytotoxicity in conjunction with antibiotics, heavy metals, polycyclic aromatic hydrocarbons (PAHs), and other toxicants. We examine mechanisms to ameliorate MP/NP-induced phytotoxicity, including the use of phytohormones, biochar, and other plant-growth regulators. We discuss the effects of MPs/NPs -induced phytotoxicity in terms of its ability to inhibit plant growth and photosynthesis, disrupt nutrient metabolism, inhibit seed germination, promote oxidative stress, alter the antioxidant defense system, and induce genotoxicity. This review summarizes the novel strategies for mitigating MPs/NPs phytotoxicity, presents recent advances, and highlights research gaps, providing a foundation for future studies aimed at overcoming the emerging problem of MPs/NPs phytotoxicity in edible crops.

Comprehensive assessment of microplastics in Australian biosolids: Abundance, seasonal variation and potential transport to agroecosystems

Striving towards a circular economy, the application of treated sewage sludge (biosolids) to land is an opportunity to improve the condition of the soil and add essential nutrients, in turn reducing the need for fertilisers. However, there is an increasing concern about microplastic (MP) contamination of biosolids and their transport to terrestrial ecosystems. In Australia, agriculture is the largest biosolids end-user, however, there is limited understanding of MPs in Australian biosolids. Also, while the method to isolate MPs from biosolid is established, a need to extract and analyse MPs more efficiently is still pressing. In this study, we comprehensively quantified and characterised MPs in 146 biosolids samples collected from thirteen wastewater treatment plants (WWTPs) including different seasons. We have optimised an oxidative-enzymatic purification method to overcome current limitations for MP identification in complex samples and accurately report MPs in biosolids. This method enabled removal of >93 % of dry weight of organic material and greatly facilitated the MPs instrumental analysis. The concentration of MPs (>20 µm) in all biosolids samples ranged from 11 to 150 MPs/g dry weight. Abundance of MPs was affected by seasons with higher abundance of MPs usually found during cold and wet seasons. Despite seasonal variations, polyethylene terephthalate, polyurethane and polymethyl methacrylate were the most abundant polymers. Smaller MPs (20 to 200 µm) comprised >70 % of all detected MPs with a clear negative linear relationship observed between MP size and abundance. Per capita concentration of MPs in biosolids across all studied WWTPs was 0.7 to 21 g MPs per person per year. Therefore, biosolids are an important sink and source of MPs to agroecosystems, emphasising the need to more comprehensively understand the fate, impact and risks associated with MPs on agricultural soils.

Long-term presence of microplastics in aerobic and anaerobic sequential batch reactors: Effect on treatment, microbial diversity, and microplastics morphology

Sewage treatment plants (STPs) are identified as the significant sink and source of microplastics (MPs) in aquatic bodies and terrestrial systems. A major fraction of MPs gets retained in STPs for a longer duration, and their potentiality for secondary MPs generation and additives leaching remain under investigated. Therefore, this study focussed on the effect of long-term exposure of aerobic and anaerobic biological sewage treatment units on MPs, along with the effect of MPs on treatment efficiency and microbial consortium. A mixture of polyvinyl chloride, polystyrene, and nylon MPs at 262 MPs/L was spiked in the aerobic and anaerobic sequential batch reactors (SBRs) for 120 days at the start of study. The study revealed a release of noteworthy fraction of secondary MPs into the reactors from spiked MPs. At the end of 120th day, the presence of secondary generated MPs was estimated as 1000 ± 71 MPs/L and 650±141 MPs/L in aerobic and anaerobic SBRs respectively. Most of the observed secondary MPs were of size < 300 µm. Leaching of additives, i.e. cyclohexylamine, cyclotetradecane, octadecanol, pipericine etc., into the SBR effluents were also observed. The depuration capacities of the reactors were not affected with the presence of MPs during the study. While the microbial diversity and abundance were negatively impacted in aerobic SBRs, no such impacts were observed in anaerobic SBRs due to MPs. These results do suggest such exposures to potentially cause secondary MPs and chemical pollution in receiving matrices for the treated effluent, as well as effect on the native microbial community.

Quantitative analysis of nanoplastics in environmental and potable waters by pyrolysis-gas chromatography-mass spectrometry

Nanoplastics are emerging environmental contaminants, but their presence in environmental and potable water remains largely understudied due to the absence of quantitative analytical methods. In this study, we developed and validated a pretreatment method that combines hydrogen peroxide digestion and Amicon® Stirred Cell ultrafiltration (at 100 kDa, approximately 10 nm) with subsequent detection by pyrolysis gas chromatography-mass spectrometry (Pyr-GC/MS). This method allows for the simultaneous identification and quantification of nine selected nanoplastic types, including poly(ethylene terephthalate) (PET), polyethylene (PE), polycarbonate (PC), polypropylene (PP), poly(methyl methacrylate) (PMMA), polystyrene (PS), polyvinylchloride (PVC), nylon 6, and nylon 66, in environmental and potable water samples based on polymer-specific mass concentration. Limits of quantification ranged from 0.01 to 0.44 µg/L, demonstrating the method's ability to quantitatively detect nanoplastics in environmental and potable water samples. Most of the selected nanoplastics were detected at concentrations of between 0.04 and 1.17 µg/L, except for PC, which was consistently below the limit of detection (<0.44 µg/L). The prevalent polymer components in the samples were PE (0.10 - 1.17 µg/L), PET (0.06 - 0.91 µg/L), PP (0.04 - 0.79 µg/L), and PS (0.06 - 0.53 µg/L) nanoplastics. The presented analytical method offers an accurate means to identify, quantify, and monitor nanoplastics in complex environmental and potable water samples. It fills gaps in our understanding of nanoplastic pollution levels, providing a valuable methodology and crucial reference data for future studies.

Fate and potential risks of microplastic fibers and fragments in water and wastewater treatment processes

Water and wastewater treatment plants (WWTPs) receive various types of microplastics (MPs), with fibers and fragments being dominant shapes. Here we investigated the removal behavior and transformation of MPs (polypropylene and polyethylene terephthalate fibers and fragments) in simulated water and wastewater treatment units, including activated sludge process, coagulation, sand filtration, and advanced oxidation/disinfection. Sand filtration demonstrated the highest average efficiency in removing MPs (98 %), followed by activated sludge process (61 %) and coagulation (55 %), which was associated with their physicochemical properties (shape, size, density, surface functional groups, etc). In activated sludge process and coagulation, the polymer type had a greater impact on the removal of MPs than the particle shape, while in sand filtration, the particle shape played a more important role. When subjected to the long-term operation and backwashing of sand filters, approximately 15 % of the initially filtered fragments broke through the sand media, with nearly no fibers escaping. UV-based advanced oxidation and chlorination induced the leaching of dissolved organic matters with different molecular characteristics from fragment MPs, resulting in varying levels of cytotoxicity and bacterial toxicity. Our study provides important information for predicting the fate of MPs and mitigating their impacts in WWTPs.

Interactions between MPs and PFASs in aquatic environments: A dual-character situation

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFASs) have drawn great attention as emerging threats to aquatic ecosystems. Although the literature to study the MPs and PFASs alone has grown significantly, our knowledge of the overlap and interactions between the two contaminations is scarce due to the unawareness of it. Actually, numerous human activities can simultaneously release MPs and PFASs, and the co-sources of the two are common, meaning that they have a greater potential for interactions. The direct interaction lies in the PFASs adsorption by MPs in water with integrated mechanisms including electrostatic and hydrophobic interactions, plus many influence factors. In addition, the existence and transportation of MPs and PFASs in the aquatic environment have been identified. MPs and PFASs can be ingested by aquatic organisms and cause more serious combined toxicity than exposure alone. Finally, curbing strategies of MPs and PFASs are overviewed. Wastewater treatment plants (WWTPs) can be an effective place to remove MPs from wastewater, while they are also an important point source of MPs pollution in water bodies. Although adsorption has proven to be a successful curbing method for PFASs, more technological advancements are required for field application. It is expected that this review can help revealing the unheeded relationship and interaction between MPs and PFASs in aquatic environments, thus assisting the further investigations of both MPs and PFASs as a whole.

Interactions between microplastics and Culex sp. larvae in wastewater

Microplastics (MPs) are a growing issue because they endanger both aquatic organisms and humans. Studies have indicated that wastewater treatment plants (WWTPs) are one of the major contributors to MPs in the environment. However, studies on the abundance of MP contamination in WWTPs and its transmission into aquatic organisms are still scarce, especially in Egypt. The goal of this study was to examine the temporal fluctuations in the distribution of MPs in surface water and the dominant macroinvertebrate fauna (Culex sp. larvae) in a fixed wastewater basin in Sohag Governorate, Egypt. The average of MPs in the surface water was 3.01 ± 0.9 particles/L. The results indicated to seasonal variation of MP abundance in the wastewater basin that was significantly higher in winter than in the other seasons. The risk index for polymers (H), pollution load index (PLI), and potential ecological risk index (RI) were used to assess the degree of MP contamination. The basin has moderate H values (<1000) because of the presence of polymers with moderate hazard scores such as polyester (PES), polyethylene (PE), and polypropylene (PP). According to the PLI values, surface water is extremely contaminated with MPs (PLI: 88 to 120). The RI values of surface water showed higher ecological risk (level V). MPs in Culex sp. larvae were seasonally changed with an 85% detection rate, and an abundance average of 0.24 ± 0.65 particles/ind, MP concentration in Culex sp. larvae was influenced by the MP characters (shape, color, and polymer). The larvae of Culex sp. showed a greater preference for black and red fibrous polyester (PES) with sizes (<1000 μm) of MPs. These findings suggest that Culex sp. larvae prefer ingesting MPs that resemble their food. It is possible to overestimate Culex sp.'s preference for lower sizes because of their catabolism of MPs. To better understand the preferences of Culex sp. larvae for MPs, further controlled trials should be conducted. PRACTITIONER POINTS: Wastewater is highly contaminated with microplastics (MPs) in the different seasons. First report of detection of the seasonal abundance of MP in Culex sp. larvae. Culex sp. larvae showed a stronger feeding preference for MPs with specific characteristics. Smaller size and blue polyester fibers were the dominant characteristics of MPs in wastewater.

Microalgal-based industry vs. microplastic pollution: Current knowledge and future perspectives

Microalgae can play a crucial role in the environment due to their efficient capture of CO2 and their potential as a solution for a carbon-negative economy. Water quality is critical for the success and profitability of microalgal-based industries, and understanding their response to emergent pollutants, such as microplastics (MPs), is essential. Despite the published studies investigating the impact of MPs on microalgae, knowledge in this area remains limited. Most studies have mainly focused on microalgal growth, metabolite analysis, and photosynthetic activity, with significant discrepancies in what is known about the impact on biomass yield. Recent studies show that the yield of biomass production depends on the levels of water contamination by MPs, making it necessary to reduce the contamination levels in the water. However, present technologies for extracting and purifying water from MPs are limited, and further research and technological advancements are required. One promising solution is the use of bio-based polymer materials, such as bacterial cellulose, which offer biodegradability, cost-effectiveness, and environmentally friendly detoxifying properties. This review summarises the current knowledge on MPs pollution and its impact on the viability and proliferation of microalgae-based industries, highlights the need for further research, and discusses the potential of bio-solutions for MPs removal in microalgae-based industries.

Microplastic Removal in Wastewater Treatment Plants (WWTPs) by Natural Coagulation: A Literature Review

Urban industrialization has caused a ubiquity of microplastics in the environment. A large percentage of plastic waste originated from Southeast Asian countries. Microplastics arising from the primary sources of personal care items and industrial uses and the fragmentation of larger plastics have recently garnered attention due to their ubiquity. Due to the rising level of plastic waste in the environment, the bioaccumulation and biomagnification of plastics threaten aquatic and human life. Wastewater treatment plant (WWTP) effluents are one of the major sources of these plastic fragments. WWTPs in Southeast Asia contribute largely to microplastic pollution in the marine environment, and thus, further technological improvements are required to ensure the complete and efficient removal of microplastics. Coagulation is a significant process in removing microplastics, and natural coagulants are far superior to their chemical equivalents due to their non-toxicity and cost-effectiveness. A focused literature search was conducted on journal repository platforms, mainly ScienceDirect and Elsevier, and on scientific databases such as Google Scholar using the keywords Wastewater Treatment Plant, Coagulation, Microplastics, Marine Environment and Southeast Asia. The contents and results of numerous papers and research articles were reviewed, and the relevant papers were selected. The relevant findings and research data are summarized in this paper. The paper reviews (1) natural coagulants for microplastic removal and their effectiveness in removing microplastics and (2) the potential use of natural coagulants in Southeast Asian wastewater treatment plants as the abundance of natural materials readily available in the region makes it a feasible option for microplastic removal.

Abundance, characterization, and removal of microplastics in different technology-based sewage treatment plants discharging into the middle stretch of the Ganga River, India

Sewage treatment plants (STPs) are considered as a prominent source for releasing microplastics (MPs) into the riverine systems. Though MPs abundance and removal efficacy in different secondary treatment technique-based STPs have been extensively studied worldwide, such studies are scarce in Indian conditions. Herein, this study comprehensively assesses MPs abundance, characterization, and their removal in the selected secondary treatment technique-based STPs discharging into the middle stretch of the Ganga River in India. MPs concentration (n/L) in influent and effluent of the STPs varied between 42 ± 10 to 150 ± 19 and 3 ± 1 to 22 ± 5, respectively. Overall, the primary treatment stage was observed to remove MPs by 23-42 %, while the secondary treatment stage removed MPs by 67-90 %. Selected technique-based STPs exhibited varying MPs removal efficacies as follows: SBR (94 %), TF (90 %), AL (88 %), UASB (87 %), ASP (85 %), FAB (84 %), and Bio-tower (77 %). MPs ranging from 50 to 250 μm were the dominant sizes, with PP, PE, and PS being the prevalent polymers. The Ganga River receives about 3 × 108 MPs/day from STP effluents, and an estimated 4.5 × 107 MPs/day are released via the sludge. This comprehensive assessment of MPs abundance and removal from different technology-based Indian STPs will allow the comparison of the generated dataset with similar studies worldwide.

Characterizing the Microplastic Content of Biosolids in Southern Ontario, Canada

The application of biosolids to agricultural land has been identified as a major pathway of microplastic (MP) pollution to the environment. Very little research, however, has been done on the MP content of biosolids within Canada. Fifteen biosolid samples from different treatment processes (liquid, dewatered, pelletized, and alkali-stabilized) were collected from 11 sources across southern Ontario to quantify and characterize the MP load within them. All samples exhibited MP concentrations ranging from 188 200 (±24 161) to 512 000 (±28 571) MPs/kg dry weight and from 4122 (±231) to 453 746 (±38 194) MPs/kg wet weight. Field amendment of these biosolids can introduce up to 3.73 × 106 to 4.12 × 108 MP/ha of agricultural soil. There was no significant difference in the MP concentrations of liquid, dewatered, and pelletized samples; but a reduction in MP content was observed in alkali-stabilized biosolids. Fragments composed 57.6% of the MPs identified, while 36.7% were fibers. In addition, MPs showed an exponential increase in abundance with decreasing size. Characterization of MPs confirmed that polyester was the most abundant, while polyethylene, polypropylene, polyamide, polyacrylamide, and polyurethane were present across the majority of biosolid samples. The results of the present study provide an estimate of the potential extent of MP contamination to agricultural fields through the amendment of biosolids. Environ Toxicol Chem 2024;00:1-14. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Removal of microplastics from water by coagulation of cationic-modified starch: An environmentally friendly solution

Microplastics (MPs) pose a potential risk to aquatic ecosystems, and there is a growing demand to alleviate the contamination of MPs. Here, we introduce cationic-modified starch (CS) as an eco-friendly bio-coagulant for removing MPs from water. CS with varying degrees of substitution was synthesized and characterized, and its performance in removing MPs was evaluated under different MP sizes, types, and aging, as well as various water conditions. The results indicated that CS efficiently removed MPs, achieving an average removal rate of 65.33 % for polystyrene particles, with higher removal rates for larger, high-density, and aged MPs. The efficiency of CS remained consistent across a wide range of water pH values, but was significantly reduced in the presence of kaolin clay or/and humic acid. The removal efficiency of CS for MPs was enhanced by the non-ionic surfactant, Tween 20, but inhibited by the anionic surfactant, cetyltrimethylammonium bromide. In addition, CS could concurrently remove both MPs and phenanthrene, as a typical water contaminant. Moreover, the applicability of CS was demonstrated in natural water samples from the Ecological Demonstration Zone of the Yangtze River Delta, China, with an average removal rate of 60.13 ± 3.15 %. Taken together, this study offers an environmentally friendly and cost-effective approach for the removal of MPs from water, demonstrating CS has significant application potential as a sustainable solution to mitigate microplastic pollution.

Evaluating the generation of microplastics from an unlikely source: The unintentional consequence of the current plastic recycling process

This study casts light on the potential of microplastic generation during plastic recycling - an unintended consequence of the process. To date, microplastics have been detected in the wastewater and sludge from plastic recycling facilities; however, generation pathways, factors and minimisation strategies are understudied. The purpose of this study is to identify the factors affecting microplastic generation, namely, plastic type and weathering conditions. The size reduction phase, which involved the mechanical shredding of the plastic waste material, was identified to be the predominate source of microplastic generation. Material type was found to significantly affect microplastic generation rates. Focussing on the microplastic particles in the size range of 0.212-1.18 mm, polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), and high-density polyethylene (HDPE) generated 28,600 ± 3961, 21,093 ± 2211, 18,987 ± 752 and 6807 ± 393 particles/kg of plastic material shredded, respectively. The significant variations between different plastic types were correlated (R2 = 0.88) to the hardness of the plastic. Environmental weathering was observed to significantly affect microplastic generation rates. Generation rates increased for PC, PET, PP, and HDPE by 185.05 %, 159.80 %, 123.70 % and 121.74 %, respectively, over a six-month environmental exposure period. The results in this study confirm production of large amounts of microplastics from the plastic recycling industry through its operational processes, which may be a significant source for microplastic pollution if measures to reduce their production and removal from wastewater and sludge are not considered.

Influence of tourism on microplastic contamination at wastewater treatment plants in the coastal municipality of Chiclana de la Frontera

The tourism is one of the most important sources of the economy in the Bay of Cadiz. Specifically, the municipality of Chiclana de la Frontera, with a population lower than 90,000 citizens, located in the southeast of Spain. During the summer season the population duplicates leading to an increment in flow at wastewater treatment plants (WWTPs). These facilities have been reported as a source of microplastics (MPs) into marine ecosystems, therefore the aim of the present study is to investigate if the tourism affects the presence, discharge and in the receiving environment. Samples were taken at the influent and effluent of the municipal WWTPs (one located at the urban area and other located at resort area) during 2021 (including low and high season). MPs were collected and extracted from wastewater matrixes following the method recommended by the National Oceanic and Atmospheric Administration and UTS treatment to reduce organic matter and cellulose, respectively. The analysis of the samples was performed according to their abundance, shape, size, and type of polymer, along with the removal rates of MPs at WWTPs. The results showed heterogeneous MPs abundance ranging from 1246.4 to 345.7 MPs/L and 72.9 to 4.2, in the influent and effluent, respectively, increasing the presence of MPs at resort WWTP during high season. Fibers were the predominant shape within all the samples. A total of 17 polymers were identified, by ATR-FTIR, where Acrylates, PE and PA were the largest polymers found. Despite the high MPs retention performance of the WWTPs analyzed (84.1-99.3 %), a combined contribution of approximately 1.4 × 107-5.9 × 108 MPs/d to the aquatic environment was estimated. Finally, these results indicate that the increase of MPs in the wastewater at WWTP-B was related with the population increase as a consequence of summer tourism.

When microplastics meet electroanalysis: future analytical trends for an emerging threat

Microplastics are a major modern challenge that must be addressed to protect the environment, particularly the marine environment. Microplastics, defined as particles ≤5 mm, are ubiquitous in the environment. Their small size for a relatively large surface area, high persistence and easy distribution in water, soil and air require the development of new analytical methods to monitor their presence. At present, the availability of analytical techniques that are easy to use, automated, inexpensive and based on new approaches to improve detection remains an open challenge. This review aims to outline the evolution and novelties of classical and advanced methods, in particular the recently reported electroanalytical detectors, methods and devices. Among all the studies reviewed here, we highlight the great advantages of electroanalytical tools over spectroscopic and thermal analysis, especially for the rapid and accurate detection of microplastics in the sub-micron range. Finally, the challenges faced in the development of automated analytical methods are discussed, highlighting recent trends in artificial intelligence (AI) in microplastics analysis.

Removal characteristics of microplastics in sewage flowing through a long-term operation surface flow wetland

Microplastics (MPs) in sewage pose significant threats to aquatic system. Surface flow wetland (SFW) is a common natural wetland type, and is also used as a cheap and easy-to-build sewage treatment system for small and scattered settlements. However, seasonal variation patterns of MPs in sewage removed by SFW are still limited. Therefore, a field investigation was conducted in an SFW that has been operated for 17 years. The concentration of microplastics in the influent of the SFW (CMPs, in) ranged from 56 ± 6 to 250 ± 14 items L-1. The dominant plastic types were fibers and polyethylene terephthalate (PET). CMPs, in were high in summer and winter, significantly related to the seasonal dressing habits. The removal efficiencies of MPs in SFW were 48.03-92.32 % in different seasons, and the mechanisms of MP removal were different with traditional pollutants. Before flowing out occasionally or by heavy precipitation, MPs were primarily trapped in the SFW and underwent certain oxidation. Simulation experiments demonstrated that 47.5-92.9 % of MPs would be trapped in the SFW, and plants would significantly enhance the trapping capacities. This study sheds light on the seasonal variation characteristics and patterns of MPs in actual sewage, and clarifies the fate of MPs in a long-term operation SFW.

A standard analytical approach and establishing criteria for microplastic concentrations in wastewater, drinking water and tap water

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.

Occurrence and distribution of microplastics in long-term biosolid-applied rehabilitation land: An overlooked pathway for microplastic entry into terrestrial ecosystems in Australia

Wastewater treatment plants (WWTPs) efficiently eliminate over 98% of microplastics (MPs) from wastewater discharge, subsequently accumulating them in sludge. This sludge is frequently employed as fertilizer in agricultural practices or land rehabilitation. While there is significant research on biosolid application in agriculture, the discussion regarding its application in rehabilitating industrial zones and MPs contamination is limited. The current study investigates the abundance, distribution, and composition of MPs in rehabilitation land with long-term biosolid-application in Australia. Three minesite fields (designated 1-3), each with distinct biosolid application histories since 2011, 2012, and 2017, and a control field without any biosolid application history, were chosen for this study. The abundances of MPs in biosolid-applied fields 1-3 (6.04 ± 1.92 x 102 MP kg-1; 4.94 ± 0.73 x 102 MP kg-1; 2.48 ± 0.70 x 102 MP kg-1) were considerably higher compared to non-biosolid-applied field (0.70 ± 0.63 x 102 MP kg -1). This indicates that the application of biosolids significantly contributes to the presence of MPs in the soil. Moreover, the results suggest that with each successive application, the abundance of MPs increases. The abundance and size of MPs in both biosolid and non-biosolid soils decreased as the soil depth increased. Microbeads were dominant in soils where biosolids were applied (up to 61.9%), while fibres were dominant in non-biosolid soils (accounting for 85.7%). The distribution of plastic polymer types varied among fields and soil depths. Most MPs were microbeads of polyamide (PA), fragments of polyethylene (PE), foam of polystyrene (PS), and fibres of rayon. This research presents evidence that the extended utilization of biosolids results in elevated MP pollution in minesite rehabilitation land, highlighting a frequently overlooked origin of MP contamination in terrestrial settings. Additional evaluations needed to understand ecological risks of MPs in soil ecosystems affected by biosolid application.

The destiny of microplastics in one typical petrochemical wastewater treatment plant

Microplastic (MP) is a type of emerging contaminant that is verified to be threatening to some organisms. Controlling MP emission from the source is preferred for its refractory characteristic. The petrochemical industry is a possible contributor, responsible for the most plastic production, and wastewater is the most possible sink of MP. This study applied the Agilent 8700 Laser infrared imaging spectrometer (LDIR) to detect MPs in one typical petrochemical wastewater treatment plant (PWWTP). It was determined that the abundances of MPs in the influent and effluent of the target PWWTP were as high as 7706 and 608 particles/L. The primary treatment removed most MPs (87.5 %) with a final removal efficiency of 92.1 %. 23 types of MPs were identified, and Polyethylene (PE), Polypropylene (PP), Silicone resin prevailed in the effluent. All the MPs were smaller than 483.9 μm. All in all, this study preliminarily unveiled the ignorable status of the petrochemical industry in releasing MPs into the water environment for the first time.

Are wastewater treatment plants as the source of microplastics in surface water and soil?

Microplastics (MPs) are widely detected in wastewater treatment plants (WWTPs) and natural environment, while the relationship of MPs pollution in both media is not fully understood. In this study, the occurrence of MPs in WWTPs and in surface water and soil was investigated, and their relationship was critically formulated. Results showed although wastewater treatment could effectively remove MPs (58.2%), the effluent was still the important source of MPs in the river, while sludge was not as important as the effluent of MPs in the soil. Specifically, the dominant size ranges of MPs were 0-200 µm, with main type of PE in all wastewater, sludge, river and soil. The dominant shape of MPs in wastewater and river was film. However, the shapes were different between sludge (52.1% of fibers) and soil (40.6% of fragment). Overall, WWTP input and surface runoff were the main source of MPs pollution in surface water, and the abrasion of agricultural films accounted for the MPs pollution in soil. The findings revealed the distribution and interconnection of MPs in WWTPs and environmental media, which could help to trace the sources of MPs pollution and assess the ecological risks in the environment.

Characterization and removal efficiencies of microplastics discharged from sewage treatment plants in Southeast Spain

Microplastics (MPs) are ubiquitous pollutants that can effectively harm different ecosystems. The information on the relative contribution of wastewater treatment plants (WWTPs) to the surrounding environment is important, in order to understand ecological health risks and implement measures to reduce their presence. This focus article presents a quantitative assessment on the relative concentration and types of MPs delivered from four WWTPs located at the Southeast of Spain. Samples from WWTPs were collected throughout a four-year period, comprising more than 1,200 L of analyzed wastewater and 3,215 microparticles isolated. Density extraction with 1.08 g/mL NaCl salt solution was systematically used as the main separation method, in a simple and reliable manner, and repeat extraction cycles did not play any significant impact on the study outcomes. The four WWTPs had removal efficiencies between 64.3% and 89.2% after primary, secondary, and tertiary treatment phases, without diurnal or daily variations. Advanced treatment methods displayed a lower removal rate for fibers than for particulate MPs. The abundance of MPs was always higher and with a lower mean size in wastewater samples collected in Autumn than for the rest of seasons. MPs dumped from WWTPs in large quantities into the environment are meant to be regarded as an important point source for aquatic and terrestrial environments.

Tracing the fate of microplastic in wastewater treatment plant: A multi-stage analysis of treatment units and sludge

Microplastic (MP) pollution is ubiquitous in the environment presenting a global problem for both scientists and the general public. One of the major pathways of MPs entering the natural environment is through wastewater treatment plants (WWTPs). Once MPs reach the natural environment, they are posing threat to aquatic ecosystems and public health. The aim of this study is to investigate the concentration, morphology, and composition of MPs in different treatment units of a WWTP. Sampling included different points across WWTP in the water and sludge lines. Pre-treatment of the samples consists of advanced Fenton oxidation, and alkaline and enzymatic digestion followed by density separation. Once the particles were isolated, their morphology and size were studied using a stereoscopic and optical microscope followed by final confirmation with ATR-FTIR and micro-FTIR spectroscopy. Microplastic particle concentrations exhibit significant reductions as water undergoes treatment in the WWTP. For summer sampling, concentrations decreased from 351 MP/L (influent) to 35 MP/L (primary clarifier), 32 MP/L (biological reactor), and 13 MP/L (2.3 MP/L) (secondary clarifier). Similarly, winter sampling showed reductions from 403 MP/L (influent) to 159 MP/L (primary clarifier), 178 MP/L (biological reactor), and 26 MP/L (5.6 MP/L) (secondary clarifier). Removal efficiency of WWTP is high and exceeds 96%. The most abundant morphology is fibers followed by fragments and films. Polymers such as PE, synthetic cellulose, PP, PVC, PE-PP, PEEA, PA, acrylamide, and PES are widely detected in different units of WWTP. The number of MPs that are avoided from being emitted into the environment through direct water discharge was estimated to be 9.1 × 1012 MP/year. Removed MPs tend to accumulate in the sludge that is used for agricultural purposes although it should be managed as waste properly, avoiding the transition of MPs pollutants to terrestrial ecosystems adding to the number of MPs that will inevitably end up in receiving water bodies through direct WWTP effluent discharge that was set in 5.1 × 1010 MP/year in the studied WWTP.

Detection of microplastic traces in four different types of municipal wastewater treatment plants through FT-IR and TED-GC-MS

Large amounts of microplastics are discharged into wastewater treatment plants (WWTPs), from where some of them are released into natural waterbodies on account of their not being fully eliminated by WWTPs. To investigate the behavior and emission of microplastics from WWTPs, we selected four WWTPs with different treatment technologies, including anaerobic-anoxic-aerobic (A2O), sequence batch reactor (SBR), media, and membrane bioreactor (MBR). The number of microplastics detected using Fourier transform infrared (FT-IR) spectroscopy ranged from 520 to 1820 particles/L in influent and from 0.56 to 2.34 particles/L in effluent. The microplastic removal efficiencies of four WWTPs were over 99%, indicating that the type of treatment technologies did not significantly affect the removal rate of microplastics. In the unit process for each WWTP, the major stages relating to microplastic removal were the secondary clarifier and tertiary treatment processes. Most microplastics detected were categorized as fragments and fibers, while other types were hardly detected. The size of more than 80% of microplastic particles detected in WWTPs ranged between 20 and 300 μm, indicating that they were significantly smaller than the size threshold defined for microplastics. Therefore, we used thermal extraction-desorption coupled with gas chromatography-mass spectroscopy (TED-GC-MS) to evaluate the microplastic mass content in all four WWTPs, and the results were compared with those of the FT-IR analysis. In this method, only four components, namely polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, were analyzed because of the analysis limitation, and the total microplastic concentration represented the sum of four components concentrations. The influent and effluent microplastic concentrations estimated by TED-GC-MS ranged from not detectable to 160 μg/L and 0.04-1.07 μg/L, respectively, indicating a correlation coefficient of 0.861 (p < 0.05) between the TED-GC-MS and FT-IR results, when compared to the combined abundance of the four microplastic components by FT-IR analysis.

Characteristics and seasonal variation of microplastics in the wastewater treatment plant: The case of Bursa deep sea discharge

Microplastics (MPs) are an emerging pollutant that can be detected in all ecosystems, especially aquatic ecosystems. Wastewater treatment plants (WWTPs) are important point sources of MP release into the sea. In this study, the characteristics of MPs in wastewater and sludge samples taken from different units of WWTP in Bursa-Gemlik district for 12 months were investigated. Wastewater and sludge samples collected from 7 different points were classified as size, shape, color, and counted. The amount of MP in the influent and effluent of the WWTP, respectively; 107.1 ± 40.2 MP/L and 4.1 ± 1.1 MP/L. Although the MP removal efficiency of the WWTP is 96.17 %, approximately 74,825,000 MP is discharged into the Marmara Sea every day. The amount of MP in the sludge is 14.3 ± 7.1 MP/g. The amount of MP accumulated in 22tons of waste sludge formed daily in WWTP was calculated as 314,600,000 MP, and the annual accumulated amount was calculated as approximately 1.15 × 1011 MP. The MPs in the WWTP were mainly 1-0.5 mm in size. Fibers were the dominant MP shape in both the wastewater and sludge samples. Black and transparent were the dominant MP colors. Seven different polymer types of MPs were detected, which were mainly types of polyethylene, polypropylene, and polyethylene terephthalate. Despite the high removal efficiency in the investigated WWTP, it has been shown that it acts as an important source of MPs to the sea ecosystem due to the high discharge rates.

How many microplastic particles are present in Canadian biosolids?

Application of treated sewage sludge (biosolids) from wastewater treatment plants (WWTPs) to farmlands is an important pathway through which microplastic particles (MPs) enter terrestrial ecosystems. Yet, microplastic concentrations in Canadian biosolids have only been estimated in samples from four WWTPs previously. We aimed to fill this knowledge gap by quantifying microplastics in biosolids from 22 WWTPs located in nine provinces and two commercial fertilizer producers in Canada. All samples had substantial microplastic concentrations ranging from 228 to 1353 particles per gram dry weight (median = 636 particles), which are orders of magnitude greater than MPs reported from earlier investigations of biosolids from other countries. Fibers (median: 86%) were the most common type of MPs observed, followed by fragments (median: 13%). There were no statistically significant differences in the amount of microplastics observed in the biosolids from different geographical regions, WWTP types, and sludge treatment processes. This suggests that diverse combinations of local sewershed characteristics, site-specific treatment approaches, and daily flow at WWTPs may be influencing concentrations of microplastics in biosolids. Our results indicate that microplastic concentrations in biosolids are substantially higher than they are in other environmental matrices, and this has important implications to managing microplastic pollution in terrestrial ecosystems.

Microplastics and Tire Wear Particles in Urban Stormwater: Abundance, Characteristics, and Potential Mitigation Strategies

Stormwater has been identified as a pathway for microplastics (MPs), including tire wear particles (TWPs), into aquatic habitats. Our knowledge of the abundance of MPs in urban stormwater and potential strategies to control MPs in stormwater is still limited. In this study, stormwater samples were collected from microlitter capture devices (inlet and outlet) during rain events. Sediment samples were collected from the material captured in the device and from the inlet and outlet of a constructed stormwater wetland. MP (>25 μm) concentration in stormwater varied across different locations ranging from 3.8 to 59 MPs/L in raw and 1.8 to 32 MPs/L in treated stormwater, demonstrating a decrease after passage through the device (35-88% removal). TWPs comprised ∼95% of all particles, followed by polypropylene (PP) and poly(ethylene terephthalate) (PET). The concentration of TWPs ranged from 2.5 to 58 TWPs/L and 1450 to 4740 TWPs/kg in stormwater and sediment, respectively. A higher abundance of MPs was found in the sediment at the inlet of the constructed wetland compared to the outlet, indicating a potential role of wetlands in removing MPs from stormwater. These findings suggest that both constructed wetlands and microlitter capture devices can mitigate the transport of MPs from stormwater to the receiving waterways.

Environmental risk of microplastics in a Mexican coastal lagoon ecosystem: Anthropogenic inputs and its possible human food risk

Coastal lagoons are ecosystems that are considered providers of a variety species of commercial value to the humans. However, they are currently threatened by a variety of anthropogenic-derived impacts, including environmental pollution by microplastics (MPs). For these reasons, it is necessary to identify suitable biomonitors for monitoring MP activities in aquatic environments and for estimating human ingestion of MPs from the consumption of commercial shellfish species. Therefore, our aims were to identify the anthropogenic activities that supply MPs into a coastal lagoon in the southern Gulf of Mexico and their variety; to determine whether oysters (Crassostrea virginica) are suitable biomonitors to perform MPs monitoring activities and to conduct an estimation of how many MPs could a human consume by the ingestion of a commercial portion of oysters harvested in this coastal lagoon. Our results noted that MP concentrations from water and sediment collected in Laguna de Terminos were 210,000 and 11.3 times higher than values reported in other protected areas worldwide. MPs chemical composition revealed that fishing and urban activities supply mainly polyethylene (21.1 %), poly (butadiene) diol (12.6 %) and polyethylene terephthalate (9.5 %). It was also determined that oysters did not reflect the spatial distribution of MPs within the study area and that a human could consume up to 806.1 MPs per 237.1 g serving of an oyster cocktail. Finally, a coastal lagoon polluted with MPs increases the risk of affecting species used for human consumption.

The unheeded inherent connections and overlap between microplastics and poly- and perfluoroalkyl substances: A comprehensive review

Microplastics (MPs) and poly- and perfluoroalkyl substances (PFASs) are receiving global attention due to their widespread presences and considerable level in the environment. Although the occurrence and fate of MPs and PFASs alone have been extensively studied, little was known about their unheeded connection and overlap between the two. Therefore, this review attempts to reveal it for the purpose of providing a new view from joint consideration of the two in the future studies. Initially, the critically examined data on the co-sources and existence of MPs and PFASs are summarized. Surprisingly, some products could be co-source of MPs and PFASs which are general in daily life while the distribution of the two is primary influenced by the human activity. Then, their interactions are reviewed based on the fact that PFASs can be sorbed onto MPs which are regarded as a vector of contaminations. The electrostatic interaction and hydrophobic contact are the predominant sorption mechanisms and could be influenced by environmental factors and properties of MPs and PFASs. The effects of MPs on the transport of PFASs in the environments, especially in aquatic environments are then discussed. Additionally, the current state of knowledge on the combined toxicity of MPs and PFASs are presented. Finally, the existing problems and future perspectives are outlined at the end of the review. This review provides an advanced understanding of the overlap, interaction and toxic effects of MPs and PFASs co-existing in the environment.