Between source and sea: The role of wastewater treatment in reducing marine microplastics

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.

Microplastics in wastewater and sludge from centralized and decentralized wastewater treatment plants: Effects of treatment systems and microplastic characteristics

Domestic wastewater treatment plants (WWTPs) play a vital role in limiting the release of microplastics (MP) into the environment. This study examined MP removal efficiency from five centralized and four decentralized domestic WWTPs in Bangkok, Thailand. MP concentrations in wastewater and sludge were comparable between centralized and decentralized WWTPs, despite these decentralized WWTPs serving smaller populations and having limited treatment capacity. The elimination of MPs ranged from 50 to 96.8% in centralized WWTPs and 14.2-53.6% in decentralized WWTPs. It is noted that the retained MPs concentrations in sludge ranged from 20,000 to 228,100 MP/kg dry weight. The prevalence of synthetic fibers and fragments could be attributed to their pathways from laundry or car tires, and the accidental release of a variety of plastic wastes ended up in investigated domestic WWTPs. Removal of MPs between the centralized and decentralized WWTPs was influenced by several impact factors including initial MP concentrations, longer retention times, MP fragmentation, and variations of MP concentrations in sludge leading to different activated sludge process configurations. Sewage sludge has become a primary location for the accumulation of incoming microplastics in WWTPs. The MPs entering and leaving each unit process were varied due to the unique characteristics of MPs, and their different treatment efficiencies. While the extended hydraulic retention period in decentralized WWTPs decreased the MP removal efficacy, the centralized WWTP with the two-stage activated sludge process achieved the highest MP removal efficiency.

Non-negligible impact of microplastics on wetland ecosystems

There has been much concern about microplastic (MP) pollution in marine and soil environments, but attention is gradually shifting towards wetland ecosystems, which are a transitional zone between aquatic and terrestrial ecosystems. This paper comprehensively reviews the sources of MPs in wetland ecosystems, as well as their occurrence characteristics, factors influencing their migration, and their effects on animals, plants, microorganisms, and greenhouse gas (GHG) emissions. It was found that MPs in wetland ecosystems originate mainly from anthropogenic sources (sewage discharge, and agricultural and industrial production) and natural sources (rainfall-runoff, atmospheric deposition, and tidal effects). The most common types and forms of MPs identified in the literature were polyethylene and polypropylene, fibers, and fragments. The migration of MPs in wetlands is influenced by both non-biological factors (the physicochemical properties of MPs, sediment characteristics, and hydrodynamic conditions) and biological factors (the adsorption and growth interception by plant roots, ingestion, and animal excretion). Furthermore, once MPs enter wetland ecosystems, they can impact the resident microorganisms, animals, and plants. They also have a role in global warming because MPs act as unique exogenous carbon sources, and can also influence GHG emissions in wetland ecosystems by affecting the microbial community structure in wetland sediments and abundance of genes associated with GHG emissions. However, further investigation is needed into the influence of MP type, size, and concentration on the GHG emissions in wetlands and the underlying mechanisms. Overall, the accumulation of MPs in wetland ecosystems can have far-reaching consequences for the local ecosystem, human health, and global climate regulation. Understanding the effects of MPs on wetland ecosystems is essential for developing effective management and mitigation strategies to safeguard these valuable and vulnerable environments.

Microplastic contamination in wastewater: Sources, distribution, detection and remediation through physical and chemical-biological methods

Microplastics are tiny plastic particles smaller than 5 mm. that have been widely detected in the environment, including in wastewater. They originate from various sources including breakdown of larger plastic debris, release of plastic fibres from textiles, and microbeads commonly used in personal care products. In wastewater, microplastics can pass through the treatment process and enter the environment, causing harm to biodiversity by potentially entering the food chain. Additionally, microplastics can act as a vector for harmful pollutants, increasing their transport and distribution in the environment. To address this issue, there is a growing need for effective wastewater treatment methods that can effectively remove microplastics. Currently, several physical and chemical methods are available, including filtration, sedimentation, and chemical degradation. However, these methods are costly, low efficiency and generate secondary pollutants. Furthermore, lack of standardization in the measurement and reporting of microplastics in wastewater, makes it difficult to accurately assess microplastic impact on the environment. In order to effectively manage these issues, further research and development of effective and efficient methods for removing microplastics from wastewater, as well as standardization in measurement and reporting, are necessary to effectively manage these detrimental contaminants.

Additives of plastics: Entry into the environment and potential risks to human and ecological health

A steep rise in global plastic production and significant discharge of plastic waste are expected in the near future. Plastics pose a threat to the ecosystem and human health through the generation of particulate plastics that act as carriers for other emerging contaminants, and the release of toxic chemical additives. Since plastic additives are not covalently bound, they can freely leach into the environment. Due to their occurrence in various environmental settings, the additives exert significant ecotoxicity. However, only 25% of plastic additives have been characterized for their potential ecological concern. Despite global market statistics highlighting the substantial environmental burden caused by the unrestricted production and use of plastic additives, information on their ecotoxicity remains incomplete. By focusing on the ecological impacts of plastic additives, the present review aims to provide detailed insights into the following aspects: (i) diversity and occurrence in the environment, (ii) leaching from plastic materials, (iii) trophic transfer, (iv) human exposure, (v) risks to ecosystem and human health, and (vi) legal guidelines and mitigation strategies. These insights are of immense value in restricting the use of toxic additives, searching for eco-friendly alternatives, and establishing or revising guidelines on plastic additives by global health and environmental agencies.

Constructed wetlands as neglected fixed source of microplastics and antibiotic resistance genes in natural water bodies?

The pollution status and the harm caused by microplastics and antibiotic resistance genes (ARGs) in aquatic ecosystems have been a growing concern. The presence of microplastics could accelerate the transfer and spread of ARGs. Before sewage reaches natural water bodies, microplastics and ARGs need to be eliminated through specific processes. Constructed wetlands are currently an effective and environmentally friendly wastewater treatment process. Research has shown significant effectiveness in removing microplastics and ARGs. Microplastics and ARGs can be removed through processes such as adsorption, capture, adhesion, and biodegradation. However, long-term continuous operation could lead to constructed wetlands becoming significant reservoirs of microplastics and ARGs. Inflow loads and seasonal variations in constructed wetlands may result in the reintroduction of persistent microplastics and ARGs into the receiving water body, establishing the constructed wetland as a continuous source of these pollutants in the receiving water body. The key to the widespread application of constructed wetlands lies in solving this challenging problem. Therefore, although constructed wetlands serve as a green strategy for removing microplastics and ARGs, there are still many gaps in our knowledge. Based on the current accumulation of microplastics and ARGs in constructed wetlands, this paper summarizes the removal of microplastics and ARGs in existing constructed wetlands and explores the interaction between them. Additionally, it proposes suggestions for optimizing the process and improving the reliability of monitoring microplastics and ARGs in sewage.

Microplastics as an emerging contaminant of concern to our environment: a brief overview of the sources and implications

Over the years, it has become evident that microplastics are one of the most important contaminants of concern requiring significant attention. The large abundance of microplastics that are currently in the environment poses potential toxicity risks to all organisms that are exposed to them. Microplastics have been found to affect the physiological and biological processes in marine and terrestrial organisms. As well as being a contaminant of concern in itself, microplastics also have the ability to act as vectors for other contaminants. The potential for microplastics to carry pollutants and transfer them to other organisms has been documented in the literature. Microplastics have also been linked to hosting antibiotic resistant bacteria and antibiotic resistance genes which poses a significant risk to the current health system. There has been a significant increase in research published surrounding the topic of microplastics over the last 5 years. As such, it is difficult to determine and find up to date and relevant information. This overview paper aims to provide a snapshot of the current and emerging sources of microplastics, how microplastics can act as a contaminant and have toxic effects on a range of organisms and also be a vector for a large variety of other contaminants of concern. The aim of this paper is to act as a tool for future research to reference relevant and recent literature in this field.

Microplastics in wastewater treatment plants and their contributions to surface water and farmland pollution in China

Wastewater treatment plants (WWTPs) are usually considered gateways for microplastics (MPs) to enter the environment because large amounts of sewage are produced and MPs are incompletely removed during treatment processes. However, the contribution of effluent MPs to aquatic environmental pollution and that of sludge application to MPs in agricultural soil are still unknown. This study examines the presence of MPs in sewage and sludge in Shenzhen WWTPs and estimates the annual mass loading of MPs from WWTPs to surface water and farmland soil in China. According to our results, for Shenzhen, the annual contribution of MPs from WWTPs (which was obtained by multiplying the annual treated sewage volume by the estimated MP density in the treated sewage) to surface water could be 70.6-302 tons. With a normalized extrapolation model of population density, the contribution of national urban WWTPs to MPs in surface water was estimated to be 734 -3.10 × 103 tons/year, of which 220-950 tons/year entered the marine environment. Furthermore, the riverine flux of MPs from WWTPs to the ocean amounts to at least 7.0%-30% based on the maximum value of WWTP contribution to MPs in surface water. For sludge, the potential contribution of MPs to agricultural soil from Shenzhen WWTPs is (1.00-2.80) × 103 tons/year. With the above calculation procedure, it was estimated that the contribution of MPs to farmland from sludge application in China is (1.30-3.90) × 104 tons/year. The source appointment results for MPs in China's agricultural soil suggested that the contributions of the main four sources, namely, atmospheric deposition, agricultural mulch film, sludge application, and organic fertilizers, are 52%, 30%, 11%, and 7.0%, respectively.

The potential of Lecane rotifers in microplastics removal

Dealing with hard-to-degrade plastics pollution of terrestrial and aquatic environments is one of the most urgent problems of the modern world. The smallest fraction (<5 mm) called micro-plastics (MP) has been found everywhere from ice in Greenland, streams, rivers, soil and even in the human placenta. The goal of our research was to assess the ability of rotifers Lecane inermis to remove micro-plastics suspended in the water column. In the experiments we investigated specific interactions between MP, biofilm and rotifers specialized in feeding on biofilm. We hypothesized that MP adhere to the biofilm and after ingestion by rotifers could be extracted from the water in the form of compact conglomerates excreted with fecal pellets. In these experiments, we demonstrated that: (i) the rotifers preferentially ingest microplastics embedded in biofilm, (ii) the presence of microplastics does not affect growth and fecundity of rotifers, and (iii) that MP aggregation is significantly improved by the presence of biofilm, additionally enhanced in the presence of rotifers. Our findings will help to understand the role of micro-grazers, such as L. inermis feeding on biofilm, in the fate of MP in nature. In the longer term, our results could help to develop biotechnological tools for MP removal from the aquatic environment.

Marine plastics, circular economy, and artificial intelligence: A comprehensive review of challenges, solutions, and policies

Global plastic production is rapidly increasing, resulting in significant amounts of plastic entering the marine environment. This makes marine litter one of the most critical environmental concerns. Determining the effects of this waste on marine animals, particularly endangered organisms, and the health of the oceans is now one of the top environmental priorities. This article reviews the sources of plastic production, its entry into the oceans and the food chain, the potential threat to aquatic animals and humans, the challenges of plastic waste in the oceans, the existing laws and regulations in this field, and strategies. Using conceptual models, this study looks at a circular economy framework for energy recovery from ocean plastic wastes. It does this by drawing on debates about AI-based systems for smart management. In the last sections of the present research, a novel soft sensor is designed for the prediction of accumulated ocean plastic waste based on social development features and the application of machine learning computations. Plus, the best scenario of ocean plastic waste management with a concentration on both energy consumption and greenhouse gas emissions is discussed using USEPA-WARM modeling. Finally, a circular economy concept and ocean plastic waste management policies are modeled based on the strategies of different countries. We deal with green chemistry and the replacement of plastics derived from fossil sources.

Microplastics in the environment: An urgent need for coordinated waste management policies and strategies

Microplastics (MPs) have become a prevalent environmental concern, exerting detrimental effects on marine and terrestrial ecosystems, as well as human health. Addressing this urgent issue necessitates the implementation of coordinated waste management policies and strategies. In this study, we present a comprehensive review focusing on key results and the underlying mechanisms associated with microplastics. We examine their sources and pathways, elucidate their ecological and human health impacts, and evaluate the current state of waste management policies. By drawing upon recent research and pertinent case studies, we propose a range of practical solutions, encompassing enhanced recycling and waste reduction measures, product redesign, and innovative technological interventions. Moreover, we emphasize the imperative for collaboration and cooperation across sectors and jurisdictions to effectively tackle this pressing environmental challenge. The findings of this study contribute to the broader understanding of microplastics and provide valuable insights for policymakers, researchers, and stakeholders alike.

The impact of microplastics on bivalve mollusks: A bibliometric and scientific review

Bivalves are important members of the ecosystem and their populations are declining globally, making them a concern for their role in ecosystem services and the fishing industry. Bivalves are excellent bioindicators of MPs pollution due to their widespread distribution, filtering capabilities, and close association with human health. Microplastics (MPs) have direct and indirect impacts on bivalves, affecting their physiology, habitat structure, food sources, and persistence of organic pollutants. This review provides an extensive overview of the impact of MPs on bivalves, covering various aspects such as their economic significance, ecological roles, and importance in biomonitoring environmental quality. The article presents the current state of knowledge on the sources and pathways of MPs in aquatic environments and their effects on bivalves. The mechanisms underlying the effects of MPs on bivalves, including ingestion, filtration activity, feeding inhibition, accumulation, bioaccumulation, and reproduction, are also discussed. Additionally, a bibliometric analysis of research on MPs in bivalves is presented, highlighting the number of papers, geographical distribution, and keyword clusters relating to MPs. Finally, the review emphasizes the importance of ongoing research and the development of mitigation strategies to reduce the negative effects of MPs pollution on bivalves and their habitats in oceans and coastal waters.

Interventions of river network structures on urban aquatic microplastic footprint from a connectivity perspective

Microplastic footprint in urban river networks can be disturbed by multiple urbanization features, and regional river structures are generally overlooked. In this research, we analyzed the distribution of microplastics and potential impact pattern of river structures on it in a typical urban river network in Nanjing, China. Surface waters of the river network were jointly detected by multiple methods, and the Renkonen similarity index was used to study spatial variabilities of microplastics characteristics. Microplastics were ubiquitous and abundant, showing five (>50 μm) and six (20∼50 μm) hotspots, and heterogeneities in the shape and type of microplastics larger than 100 μm were prominent, presumably influenced by river network scale and connectivity. River structure parameters associated with network connectivity were obtained by combining graph theory and an entropy-based set-pair analysis model. Aiming at the action pathway of river structures, by using correlation and partial least squares regression analysis, we found that river node (confluences and sluices) ratio, river frequency, river network density, and water system circularity were significantly positively correlated with microplastic abundance, and confluences with poor connectivity had a greater indirect intervention intensity on the microplastic distribution. The land use characteristics dominated the fitting of microplastic abundance, which was about 1.2 times better than river structures, and the comprehensive land use intensity and river network connectivity were the critical factors, respectively. Potential ecological risks of microplastics were evaluated, resulting in relatively severe levels. This study proposed targeted measures to control urban microplastic pollution by combining the perspective of river network characteristics. To summarize, our exploration of microplastic footprint based on urban river network structures from the perspective of river network connectivity provides new insights into microplastic management.

Microplastic Pollution Prevention: The Need for Robust Policy Interventions to Close the Loopholes in Current Waste Management Practices

Plastic materials that are less than 5 mm in size are defined as Microplastics (MPs). MPs that are intentionally produced are called primary MPs; however, the most abundant type in the environment consists of the remainder created by the fragmentation of large plastic debris through physical, chemical, and oxidative processes, which are called secondary MPs. Due to their abundance in the environment, poor degradability, toxicological properties, and negative impact on aquatic and terrestrial organisms, including humans, MP pollution has become a global environmental issue. Combatting MP pollution requires both remediation and preventive measures. Although remediation is a must, considering where the technology stands today, it may take long time to make it happen. Prevention, on the other hand, can be and should be done now. However, the effectiveness of preventive measures depends heavily on how well MP escape routes are researched and understood. In this research, we argue that such escape routes (rather, loopholes) exist not only due to mismanaged plastic waste, but also due to cracks in the current waste management systems. One known MP loophole is facilitated by wastewater treatment plants (WWTP). The inability of existing WWTP to retain finer MPs, which are finally released to water bodies together with the treated wastewater, along with the return of captured larger MPs back to landfills and their release into the environment through land applications, are a few examples. Organic waste composting and upcycling of waste incineration ash provide other MP escape pathways. In addition, it is important to understand that the plastics that are in current circulation (active use as well as idling) are responsible for producing MPs through regular wear and tear. Closing these loopholes may be best attempted through policy interventions.

Nano and microplastics occurrence in wastewater treatment plants: A comprehensive understanding of microplastics fragmentation and their removal

Nano/microplastic (NP/MP) pollution is a growing concern for the water environment. Wastewater treatment plants (WWTPs) are considered the major recipients of MP before discharging into local waterbodies. MPs enter WWTPs mainly from synthetic fibers through washing activities and personal care products. To control and prevent NP/MP pollution, it is essential to have a comprehensive understanding of their characteristics, fragmentation mechanisms, and the effectiveness of the current treatment processes used in WWTPs for NP/MP removal. Therefore, the objectives of this study are to (i) understand the detailed mapping of NP/MP in the WWTP, (ii) understand the fragmentation mechanisms of MP into NP, and (iii) investigate the removal efficiency of NP/MP by existing processes in the WWTP. This study found that fiber is the dominant shape of MP, and polyethylene, polypropylene, polyethylene terephthalate, and polystyrene are the major polymer type of MP in wastewater samples. Crack propagation and mechanical breakdown of MP due to water shear forces induced by treatment facilities (e.g., pumping, mixing, and bubbling) could be the major causes for NP generation in the WWTP. Conventional wastewater treatment processes are ineffective for the complete removal of MPs. Although these processes are capable of removing ∼95% of MPs, they tend to accumulate in sludge. Thus, a significant number of MPs may still be released into the environment from WWTPs on a daily basis. Therefore, this study suggested that using DAF process in the primary treatment unit can be an effective strategy to control MP in the initial stage before it goes to the secondary and tertiary stage.

Fibrous microplastics released from textiles: Occurrence, fate, and remediation strategies

Microplastics (MP), i.e., particles measuring less than 5 mm in size, are considered emerging pollutants. The ubiquity of MP is causing great concern among environmental and public health agencies. Anthropogenic activities are responsible for the extensive dispersal of MP in nature. Adverse effects on living organisms, interactions with other contaminants occurring in the environment, and the lack of effective degradation/removal techniques are significant issues related to MP. Most MP found in nature are fibrous (FMP). FMP originate from textile products, mainly synthetic fibers (e.g., polyester). Synthetic fibers are intensively used to produce countless goods due to beneficial characteristics such as high mechanical resistance and economic feasibility. FMP are ubiquitous on the planet and impart lasting adverse effects on biodiversity. Data on the consequences of long-term exposure to these pollutants are scarce in the literature. In addition, few studies address the main types of synthetic microfibers released from textiles, their occurrence, adverse effects on organisms, and remediation strategies. This review discusses the relevant topics about FMP and alerts the dangers to the planet. Furthermore, future perspectives and technological highlights for the FMP mitigation/degradation are presented.

A Path to a Reduction in Micro and Nanoplastics Pollution

Microplastics (MP) are plastic particles less than 5 mm in size. There are two categories of MP: primary and secondary. Primary or microscopic-sized MP are intentionally produced material. Fragmentation of large plastic debris through physical, chemical, and oxidative processes creates secondary MP, the most abundant type in the environment. Microplastic pollution has become a global environmental problem due to their abundance, poor biodegradability, toxicological properties, and negative impact on aquatic and terrestrial organisms including humans. Plastic debris enters the aquatic environment via direct dumping or uncontrolled land-based sources. While plastic debris slowly degrades into MP, wastewater and stormwater outlets discharge a large amount of MP directly into water bodies. Additionally, stormwater carries MP from sources such as tire wear, artificial turf, fertilizers, and land-applied biosolids. To protect the environment and human health, the entry of MP into the environment must be reduced or eliminated. Source control is one of the best methods available. The existing and growing abundance of MP in the environment requires the use of multiple strategies to combat pollution. These strategies include reducing the usage, public outreach to eliminate littering, reevaluation and use of new wastewater treatment and sludge disposal methods, regulations on macro and MP sources, and a wide implementation of appropriate stormwater management practices such as filtration, bioretention, and wetlands.

Mechanism of nanoplastics capture by jellyfish mucin and its potential as a sustainable water treatment technology

The accumulation of nanoplastics (NPs) in the environment has raised concerns about their impact on human health and the biosphere. The main aim of this study is to understand the mechanism that governs the capture of NPs by jellyfish mucus extracted from the jellyfish Aurelia sp. (A.a.) and compare the capture/removal efficiency to that of conventional coagulants and mucus from other organisms. The efficacy of A.a mucus to capture polystyrene and acrylic NPs (∼100 nm) from spiked wastewater treatment plant (WWTP) effluent was evaluated. The mucus effect on capture kinetics and destabilization of NPs of different polymer compositions, sizes and concentrations was quantified by means of fluorescent NPs, dynamic light scattering and zeta potential measurements and visualized by scanning electron microscopy. A dosing of A.a. mucus equivalent to protein concentrations of ∼2-4 mg L^-1 led to a rapid change in zeta potential from a baseline of -30 mV to values close to 0 mV, indicating a marked change from a stable to a non-stable dispersion leading to a rapid (<10 min) and significant removal of NPs (60 %-90 %) from a stable suspension. The A.a. mucus outperformed all other mucus types (0-37 %) and coagulants (0 %-32 % for ferric chloride; 23-40 % for poly aluminum chlorohydrate), highlighting the potential for jellyfish mucus to be used as bio-flocculant. The results indicate a mucus-particle interaction consisting of adsorption-bridging and "mesh" filtration. Further insight is provided by carbohydrate composition and protein disruption analysis. Total protein disruption resulted in a complete loss of the A.a. mucus capacity to capture NPs, while the breaking of disulfide bonds and protein unfolding resulted in improved capture capacity. The study demonstrates that natural jellyfish mucin can capture and remove NPs in water and wastewater treatment systems more efficiently than conventional coagulants, highlighting the potential for development of a new type of bio-flocculant.

Microplastics (MPs) in marine food chains: Is it a food safety issue?

The enormous usage of plastic over the last seven decades has resulted in a massive quantity of plastic waste, much of it eventually breaking down into microplastic (MP) and nano plastic (NP). The MPs and NPs are regarded as emerging pollutants of serious concern. Both MPs and NPs can have a primary or secondary origin. Their ubiquitous presence and ability to sorb, desorb, and leach chemicals have raised concern over their presence in the aquatic environment and, particularly, the marine food chain. MPs and NPs are also considered vectors for pollutant transfer along with the marine food chain, and people who consume seafood have began significant concerns about the toxicity of seafood. The exact consequences and risk of MP exposure to marine foods are largely unknown and should be a priority research area. Although several studies have documented an effective clearance mechanism by defecation, significant aspect has been less emphasized for MPs and NPs and their capability to translocate in organs and clearance is not well established. The technological limitations to study these ultra-fine MPs are another challenge to be addressed. Therefore, this chapter discusses the recent findings of MPs in different marine food chains, their translocation and accumulations potential, MPs as a critical vector for pollutant transfer, toxicology impact, cycling in the marine environment and seafood safety. Besides, the concerns and challenges that are overshadowed by findings for the significance of MPs were covered.

Spatiotemporal distribution of seabed litter in the SE Levantine Basin during 2012-2021

This study explores the first record of spatiotemporal distributions of macro and micro-litter on the seafloor in the Southeastern (SE) Levantine Basin (LB) during 2012-2021. Macro-litter was surveyed by bottom trawls in water depths of 20-1600 m and micro-litter by sediment box corer/grab at a depths range of 4-1950 m. Maximal macro-litter concentrations were recorded at the upper continental slope (200 m), averaging 4700 ± 3000 items/km². Plastic bags and packages were the most abundant items (77 ± 9 %) with a maximum of 89 % at 200 m depth, and their size decreased with increasing water depth. Micro-litter debris were found mainly in shelf sediments (≤30 m water depth) with an average concentration of 40 ± 50 items/kg, while shit particles transferred to the deep sea. These findings suggest an extensive distribution of plastic bags and packages in the SE LB, predominantly accumulating in the upper continental slope and deeper, based on their size.

A comprehensive assessment of plastic remediation technologies

The global presence of plastic litter and its accumulation in the environment has become an issue of concern to the public and policymakers. This concern has triggered innovators in past decades to design and develop a multitude of remediation technologies to prevent plastic from entering the environment, or to clean up legacy litter. This study aims to (i) systematically review the current scientific literature on plastic remediation technologies, (ii) create a 'plastic clean-up and prevention overview' illustrating 124 remediation technologies and 29 characteristics, (iii) qualitatively analyse their key characteristics (e.g., fields of application, targeted plastic), and (iv) investigate challenges and opportunities of clean-up technologies for inland waterways (e.g., canals, rivers) and ports. We identified 61 scientific publications on plastic remediation technologies, until June 2022. Thirty-four of these studies were published within the last three years, demonstrating a growing interest. The presented overview indicates that inland waterways are, so far, the preferred field of application, with 22 technologies specifically designed for cleaning up plastics from inland waterways, and 52 additional ones with the potential to be installed in these locations. Given the importance of clean-up technologies in inland waterways, we highlighted their strengths, weaknesses, opportunities, and threats (SWOT). Our results indicate that, despite the challenges, these technologies provide essential prospects, from improving the environmental quality to raising awareness. Our study is instrumental as it illustrates an up-to-date overview and provides a comprehensive analysis of current in design phase, testing, and in use plastic remediation technologies.

Microplastic dynamics in a free water surface constructed wetland

This study investigates microplastic (MPs) dynamics of a recently established surface flow 2100 population equivalent polishing constructed wetland (CW) receiving 1.4 ML per day of secondary treated wastewater. MPs type, size ranges and concentrations were measured along the CW at a 2-months sampling campaign. The CW received an average of 5·10⁶ MPs per day (6 MPs per liter), mostly 100-1000 μm-sized synthetic fibers followed by fragments in the same size range. 95 % of MPs were retained, resulting in 0.30 ± 0.09 MPs per liter in CW effluent. Most MPs (97 %) were trapped within the first 20 % of the CW which consisted of a settling pond and shallow vegetated treatment cells and provided an areal removal rate > 4000 MP m^-2 d^-1. Data and microscopic analysis indicate MPs erosion and fragmentation in the CW. Turbidity and suspended solids were no indicator for MP removal due to water fowl activity, algal growth, and preferential flow conditions. This is the first study on MP dynamics in an independently operating full scale free water surface CW incorporated into a municipal wastewater treatment scheme. Surface flow CWs can retain MPs effectively but accumulation in CW sediments and substrate needs to be considered when further utilized or recycled.

Microplastics in wastewater treatment plants: Sources, properties, removal efficiency, removal mechanisms, and interactions with pollutants

Since wastewater treatment plants (WWTPs) cannot completely remove microplastics (MPs) from wastewater, WWTPs are responsible for the release of millions of MPs into the environment even in 1 day. Therefore, knowing the sources, properties, removal efficiencies and removal mechanisms of MPs in WWTPs is of great importance for the management of MPs. In this paper, firstly the sources of MPs in WWTPs and the quantities and properties (polymer type, shape, size, and color) of MPs in influents, effluents, and sludges of WWTPs are presented. Following this, the MP removal efficiency of different treatment units (primary settling, flotation, biological treatment, secondary settling, filtration-based treatment technologies, and coagulation) in WWTPs is discussed. In the next section, details about MP removal mechanisms in critical treatment units (settling and flotation tanks, bioreactors, sand filters, membrane filters, and coagulation units) in WWTPs are given. In the last section, the mechanisms and factors that are effective in adsorbing organic-inorganic pollutants in wastewater to MPs are presented. Finally, the current situation and research gap in these areas are identified and suggestions are provided for topics that need further research in the future.

Adsorptive behavior of micro(nano)plastics through biochar: Co-existence, consequences, and challenges in contaminated ecosystems

The abundance of micro(nano)plastics in natural ecosystems is a crucial global challenge, as these small-sized plastic particles originate from land-based and marine-based activities and are widely present in marine, freshwater, and terrestrial ecosystems. Micro(nano)plastics can significantly be reduced through various methods, such as biological, chemical, and physical techniques. Biochar is a low-cost adsorbent and is considered an efficient material and its application is ecologically effective carbon-negative for remediation of organic and inorganic pollutants. Therefore, this review critically discusses the fate and transport of micro(nano)plastics and their interactions with different biochar in aqueous and column porous media. This review outlines the implications of biochar with the co-existence of micro(nano)plastics in efforts to understand their coupled effects on soil physicochemical properties, microbial communities, and plant growth, along with the removal of heavy metals and other toxic contaminants. In batch experiments, biochar synthesized from various biomasses such as corn straw, hardwood, pine and spruce bark, corncob, and Prosopis juliflora had shown high level of removal efficiency (>90 %) for microplastic adsorption under varying environmental conditions viz., pH, temperature, ionic strength, particle size, and dose due to chemical bonding and electrostatic attractions. Increased temperature of the aqueous solutions encouraged higher adsorption, while higher pH and dissolved organic matter and nutrients may show decreased adsorption capacities for micro(nano)plastics using biochar. Compared to other available physical, chemical, and biological methods, biochar-amended sand filters in column experiments have been very efficient in removing micro(nano)plastics. In saturated column porous media, various microplastics could be inhibited using biochar due to decreased electrostatic repulsion, steric hindrance, and competitive sorption due to humic acid, ionic strength, and cations. Finally, this review provides in-depth insights on further investigations and recommendations for overall micro(nano)plastics removal using biochar-based materials.

Plastic waste in sandy beaches and surface water in Thanh Hoa, Vietnam: abundance, characterization, and sources

The occurrence and characterization of marine debris on beaches bring opportunities to track back the anthropogenic activities around shorelines as well as aid in waste management and control. In this study, the three largest beaches in Thanh Hoa (Vietnam) were examined for plastic waste, including macroplastics (≥ 5 mm) on sandy beaches and microplastics (MPs) (< 5 mm) in surface water. Among 3803 items collected on the beaches, plastic waste accounted for more than 98%. The majority of the plastic wastes found on these beaches were derived from fishing boats and food preservation foam packaging. The FT-IR data indicated that the macroplastics comprised 77% polystyrene, 17% polypropylene, and 6% high-density polyethylene, while MPs discovered in surface water included other forms of plastics such as polyethylene- acrylate, styrene/butadiene rubber gasket, ethylene/propylene copolymer, and zein purified. FT-IR data demonstrated that MPs might also be originated from automobile tire wear, the air, and skincare products, besides being degraded from macroplastics. The highest abundance of MPs was 44.1 items/m³ at Hai Tien beach, while the lowest was 15.5 items/m³ at Sam Son beach. The results showed that fragment form was the most frequent MP shape, accounting for 61.4 ± 14.3% of total MPs. MPs with a diameter smaller than 500 μm accounted for 70.2 ± 7.6% of all MPs. According to our research, MPs were transformed, transported, and accumulated due to anthropogenic activities and environmental processes. This study provided a comprehensive knowledge of plastic waste, essential in devising long-term development strategies in these locations.

Microplastic in the Baltic Sea: A review of distribution processes, sources, analysis methods and regulatory policies

Microplastics pollution is an issue of great concern for scientists, governmental bodies, ecological organisations, and the general public. Microplastics pollution is widespread and is a great environmental problem on account of its potential toxicity for marine biota and human health. Today, almost all the world's seas and oceans are polluted with microplastics. The Baltic Sea is a semi-enclosed reservoir of brackish water and is a hotspot for contamination in terms of eutrophication and the presence of organic matter. Microplastics are quite intense, based on data from studies of marine litter and microplastics in the Baltic Sea. The number of microplastics in the Baltic Sea water is 0.07-3300 particles/m³, and in sediments 0-10179 particles/kg. These amounts prove that the waters and sediments of the Baltic Sea are heavily contaminated with microplastics. This article provides a comprehensive review of the microplastic origins and transport routes to the Baltic Sea. The data is presented as the concentration of microplastics in surface waters, sediments, and sea sand. The extraction methods used and the microplastics techniques are also presented. The possibilities and limitations of water and sediment sampling methods for microplastics determination were summarised, taking into account sampling tools, volume and depth. Extraction, separation, filtration, and visual sorting are outlined as sample preparation techniques for microplastic analysis. This review also focuses on the problems of obtaining data relevant to the development of the mathematical models necessary to monitor trends in the spread of microplastics in the Baltic Sea. Finally, several important laws and policies, which are in place in the Baltic States to control and manage microplastic pollution in the region, are highlighted.

The fate of microplastic in sludge management systems

Sewage sludge (SS) from wastewater treatment plants (WWTPs) is commonly used as a soil amendment on agricultural land; however, this sludge contains microplastics (MPs) which harm soil ecosystems and can leach into aquatic environments. This review aims to assess the fate of MPs in SS systems and, in the context of a changing agricultural scene, present alternatives for sustainable SS disposal that are consistent with the practices of a clean, circular economy. Anaerobic digestion and composting, which are commonly used to stabilize SS before land application, were not reported to substantially affect MP removal, although process efficiency and the microbiome were affected by MPs. Alternatively, MPs can be destroyed or removed by mono-incineration or combustion, but unfortunately, some MPs may remain in the ash after these processes. Therefore, the most desirable solutions would prevent MPs from entering the environment and remove them before they enter the biological part of a WWTP, where they build up in SS. Additionally, the management of MP-containing sludge must be adapted to the geographical context and the local economy, and it should begin with legislation addressing MPs in SS. The information presented here will help to develop good practices in waste management for preventing or decreasing the transfer of MPs into the environment.

Risk associated with microplastics in urban aquatic environments: A critical review

The presence of microplastics (MPs) has been recognized as a significant environmental threat due to adverse effects spanning from molecular level, organism health, ecosystem services to human health and well-being. MPs are complex environmental contaminants as they bind to a wide range of other contaminants. MPs associated contaminants include toxic chemical substances that are used as additives during the plastic manufacturing process and adsorbed contaminants that co-exist with MPs in aquatic environments. With the transfer between the water column and sediments, and the migration within aquatic systems, such contaminants associated MPs potentially pose high risk to aquatic systems. However, only limited research has been undertaken currently to link the environmental risk associated with MPs occurrence and movement behaviour in aquatic systems. Given the significant environmental risk and current knowledge gaps, this review focuses on the role played by the abundance of different MP species in water and sediment compartments as well as provides the context for assessing and quantifying the multiple risks associated with the occurrence and movement behaviour of different MP types. Based on the review of past literature, it is found that the physicochemical properties of MPs influence the release/sorption of other contaminants and current MPs transport modelling studies have primarily focused on virgin plastics rather than aged plastics. Additionally, risk assessment of contaminants-associated MPs needs significantly more research. This paper consolidates the current state-of-the art knowledge on the source to sink movement behaviour of MPs and methodologies for assessing the risk of different MP species. Moreover, knowledge gaps and emerging trends in the field are also identified for future research endeavours.

The application of bioremediation in wastewater treatment plants for microplastics removal: a practical perspective

Wastewater treatment plants (WWTPs) play the role of intercepting microplastics in the environment and provide a platform for bioremediation to remove microplastics. Despite, this opportunity has not been adequately studied. This paper shows the potential ways microplastics-targeted bioremediation could be incorporated into wastewater treatment through the review of relevant literature on bioaugmentation of water treatment processes for pollutants removal. Having reviewed more than 90 papers in this area, it highlights that bioremediation in WWTPs can be employed through bioaugmentation of secondary biological treatment systems, particularly the aerobic conventional activated sludge, sequencing batch reactor, membrane bioreactor and rotating biological contactor. The efficiency of microplastics removal, however, is influenced by the types and forms of microorganisms used, the polymer types and the incubation time (100% for polycaprolactone with Streptomyces thermoviolaceus and 0.76% for low-density polyethylene with Acinetobacter iwoffii). Bioaugmentation of anaerobic system, though possible, is constrained by comparatively less anaerobic microplastics-degrading microorganisms identified. In tertiary system, bioremediation through biological activated carbon and biological aerated filter can be accomplished and enzymatic membrane reactor can be added to the system for deployment of biocatalysts. During sludge treatment, bioaugmentation and addition of enzymes to composting and anaerobic digestion are potential ways to enhance microplastics breakdown. Limitations of bioremediation in wastewater treatment include longer degradation time of microplastics, incomplete biodegradation, variable efficiency, specific microbial activities and uncertainty in colonization. This paper provides important insight into the practical applications of bioremediation in wastewater treatment for microplastics removal.

An enlarging ecological risk: Review on co-occurrence and migration of microplastics and microplastic-carrying organic pollutants in natural and constructed wetlands

Wetlands are a key hub for the accumulation of microplastics (MPs) and have great load capacity to organic pollutants (OPs), thus, have been a hot research topic. It has shown that OPs adsorbed on MPs could be transported to anywhere and MP-associated biofilms also affects the co-occurrence of MPs and OPs. This would induce the desorption of MP-carrying OPs into environment again, increasing latent migration and convergence of MPs and OPs in wetlands. Considering MPs vector effect and MP-associated biofilms, it is necessary to integrate MPs information on its occurrence characteristics and migration behavior for an improved assessment of ecological risk brought by MPs and MP-carrying OPs to whole wetland ecosystems. In this review, we studied papers published from 2010 to 2020, focused on the interaction of MPs with OPs and the role of their co-occurrence and migration on ecological risk to wetlands. Results suggested the interaction between MPs and OPs dominated by adsorption altered their toxicity and environmental behavior, and the corresponding ecological risk induced by their co-occurrence to wetlands is various and complicated. Especially, constructed wetlands as the special hub for the migration of MPs and MP-carrying OPs might facilitate their convergence between natural and constructed wetlands, posing a potential enlarging ecological risk to whole wetlands. Since the study of MPs in wetlands has still been in a primary stage, we hope to provide a new sight to set forth the potential harm of MPs and MP-carrying OPs to wetlands and useful information for follow-up study.

Immobilized enzyme/microorganism complexes for degradation of microplastics: A review of recent advances, feasibility and future prospects

Environmental prevalence of microplastics has prompted the development of novel methods for their removal, one of which involves immobilization of microplastics-degrading enzymes. Various materials including nanomaterials have been studied for this purpose but there is currently a lack of review to present these studies in an organized manner to highlight the advances and feasibility. This article reviewed more than 100 peer-reviewed scholarly papers to elucidate the latest advances in the novel application of immobilized enzyme/microorganism complexes for microplastics degradation, its feasibility and future prospects. This review shows that metal nanoparticle-enzyme complexes improve biodegradation of microplastics in most studies through creating photogenerated radicals to facilitate polymer oxidation, accelerating growth of bacterial consortia for biodegradation, anchoring enzymes and improving their stability, and absorbing water for hydrolysis. In a study, the antimicrobial property of nanoparticles retarded the growth of microorganisms, hence biodegradation. Carbon particle-enzyme complexes enable enzymes to be immobilized on carbon-based support or matrix through covalent bonding, adsorption, entrapment, encapsulation, and a combination of the mechanisms, facilitated by formation of cross-links between enzymes. These complexes were shown to improve microplastics-degrading efficiency and recyclability of enzymes. Other emerging nanoparticles and/or enzymatic technologies are fusion of enzymes with hydrophobins, polymer binding module, peptide and novel nanoparticles. Nonetheless, the enzymes in the complexes present a limiting factor due to limited understanding of the degradation mechanisms. Besides, there is a lack of studies on the degradation of polypropylene and polyvinyl chloride. Genetic bioengineering and metagenomics could provide breakthrough in this area. This review highlights the optimism of using immobilized enzymes/microorganisms to increase the efficiency of microplastics degradation but optimization of enzymatic or microbial activities and synthesis of immobilized enzymes/microorganisms are crucial to overcome the barriers to their wide application.

Plastic Interactions with Pollutants and Consequences to Aquatic Ecosystems: What We Know and What We Do Not Know

Plastics are a group of synthetic materials made of organic polymers and some additives with special characteristics. Plastics have become part of our daily life due to their many applications and uses. However, inappropriately managed plastic waste has raised concern regarding their ecotoxicological and human health risks in the long term. Due to the non-biodegradable nature of plastics, their waste may take several thousands of years to partially degrade in natural environments. Plastic fragments/particles can be very minute in size and are mistaken easily for prey or food by aquatic organisms (e.g., invertebrates, fishes). The surface properties of plastic particles, including large surface area, functional groups, surface topography, point zero charge, influence the sorption of various contaminants, including heavy metals, oil spills, PAHs, PCBs and DDT. Despite the fact that the number of studies on the biological effects of plastic particles on biota and humans has been increasing in recent years, studies on mixtures of plastics and other chemical contaminants in the aquatic environment are still limited. This review aims to gather information about the main characteristics of plastic particles that allow different types of contaminants to adsorb on their surfaces, the consequences of this adsorption, and the interactions of plastic particles with aquatic biota. Additionally, some missing links and potential solutions are presented to boost more research on this topic and achieve a holistic view on the effects of micro- and nanoplastics to biological systems in aquatic environments. It is urgent to implement measures to deal with plastic pollution that include improving waste management, monitoring key plastic particles, their hotspots, and developing their assessment techniques, using alternative products, determining concentrations of micro- and nanoplastics and the contaminants in freshwater and marine food-species consumed by humans, applying clean-up and remediation strategies, and biodegradation strategies.

Reuse of Water Contaminated by Microplastics, the Effectiveness of Filtration Processes: A Review

Water treatment generally does not specifically address the removal of microplastics (MPs). Nevertheless, treatment plants process water effectively, and the number of synthetic microparticles in effluents is usually very low. Still, discharge volumes from water-treatment plants are often elevated (reaching around 108 L/day), leading to the daily discharge of a substantial number of MPs and microfibers. Furthermore, MPs accumulate in the primary and secondary sludge, which in the end results in another environmental problem as they are currently used to amend soils, both for cultivation and forestry, leading to their dispersion. Something similar occurs with the treatment of water intended for human consumption, which has a much lower but still significant number of MPs. The amount of these pollutants being released into the environment depends on the processes that the water undergoes. One of the most-used treatment processes is rapid sand filtration, which is reviewed in this article. During the filtration process, MPs can break into smaller pieces, resulting in a greater number of plastic particles which mainly accumulate in sewage sludge. Thermal processes, such as incineration, carried out in facilities with the best available techniques in practice, could guarantee the safe disposal of highly MP-contaminated sewage sludges.

Synthetic microfibers and tyre wear particles pollution in aquatic systems: Relevance and mitigation strategies

Evidence shows that the majority of aquatic field microplastics (MPs) could be microfibers (MFs) which can be originated directly from massive sources such as textile production and shedding from garments, agricultural textiles and clothes washing. In addition, wear and tear of tyres (TRWPs) emerges as a stealthy major source of micro and nanoplastics, commonly under-sampled/detected in the field. In order to compile the current knowledge in regards to these two major MPs sources, concentrations of concern in aquatic environments, their distribution, bulk emission rates and water mitigation strategies were systematically reviewed. Most of the aquatic field studies presented MFs values above 50%. MPs concentrations varied from 0.3 to 8925 particles m^-3 in lakes, from 0.69 to 8.7 × 10⁶ particles m^-3 in streams and rivers, from 0.16 to 192000 particles m^-3 estuaries, and from 0 to 4600 particles m^-3 in the ocean. Textiles at every stage of production, use and disposal are the major source of synthetic MFs to water. Laundry estimates showed an averaged release up to 279972 tons year^-1 (high washing frequency) from which 123000 tons would annually flow through untreated effluents to rivers, streams, lakes or directly to the ocean. TRWPs in the aquatic environments showed concentrations up to 179 mg L^-1 (SPM) in runoff river sediments and up to 480 mg g^-1 in highway runoff sediments. Even though average TRWR emission is of 0.95 kg year^-1 per capita (10 nm- 500 μm) there is a general scarcity of information about their aquatic environmental levels probably due to no-availability or inadequate methods of detection. The revision of strategies to mitigate the delivering of MFs and TRWP into water streams illustrated the importance of domestic laundry retention devices, Waste Water Treatment Plants (WWTP) with at least a secondary treatment and stormwater and road-runoff collectors quality improvement devices.

Ingestion of polyethylene microspheres occur only in presence of prey in the jellyfish Aurelia aurita

Microplastic ingestion was studied in A. aurita, a bloom-forming, circumglobal medusa. Here, we determined whether factors such as the concentration of polyethylene microspheres (75-90 μm) or the absence/presence of prey affect the ingestion, duration of microspheres in the gastrovascular cavity (time of presence), and retention time. The presence of polyethylene microspheres' was determined by exposing medusae during 480 min to three different treatments (5000, 10,000, 20,000 particles L^-1), and was checked every 10 min to ascertain whether they had incorporated any. Preliminary results show that microsphere ingestion occurred only in the presence of prey (⁓294 Artemia nauplii L^-1). The time of presence of microbeads in A. aurita increased (103, 177, and 227 min), with increasing microplastic concentration, and the microbeads were egested within 150 min. This study initiates the understanding of the potential implications that arise of the encounter between jellyfish and microplastic agglomerates, and with perspectives for future research.

Microplastic retention in small and medium municipal wastewater treatment plants and the role of the disinfection

Wastewater treatment plants (WWTPs) efficiently retain microplastic particles (MPs) generated within urban areas. Among the wastewater treatment steps, disinfection has not been characterized for its potential MPs retention activity, although it has been reported that processes used to abate the bacterial load could also affect MPs concentration. For this reason, we evaluated the MPs concentration across the overall wastewater treatment process and before and after the disinfection step in four small/medium WWTPs located in the north of Italy. Most of the MPs found in the samples were fibers or fragments, smaller than 500 μm, mainly composed of polyethylene, polypropylene, or polyethylene terephthalate. The retention efficiency at the outlets was higher than 94% in all the plants analyzed. More interestingly, the disinfection treatments adopted by the different WWTPs reduced MPs concentration from a minimum of 9.1% (UV treatment) to a maximum of 67.6% (chlorination), promoting a further increase of the overall retention efficiency of the WWTPs from 0.4 to 0.7%. Quantitatively, the disinfection contributes to the MPs reduction in the outlets by retaining 0.5-6.7 million MPs per day, in WWTPs that discharge 2.7-12 million MPs per day. The results of the present work underline the importance of a careful choice of the steps that constitute the wastewater treatment, including disinfection, in order to minimize MPs discharge into the natural ecosystems.

Fate, source and mass budget of sedimentary microplastics in the Bohai Sea and the Yellow Sea

As reservoirs for pollutants transported via the Yangtze and Yellow Rivers, the Bohai Sea (BS) and Yellow Sea (YS) play an important role in transporting microplastics (MPs) to the Pacific Ocean. The fate, sources and mass budget of MPs in the BS and the YS were investigated by Pearson correlation, principal component analysis-multilinear regression analysis (PCA-MRLA) and a mass balance model to sedimentary MPs data. Average MP abundances were 137 and 119 items kg^-1 in the Bohai and Yellow Seas, respectively. MPs <1000 μm exhibited similar distribution patterns to total organic carbon and fine-grained sediments, while MPs >1000 μm were confined in the BS and exhibited a strong positive correlation with chlorophyll-a and polyethylene terephthalate, suggesting that larger MPs might deposit faster due to biofouling or when comprised of high density polymers. PCA-MLRA analysis indicated land-based inputs (packing materials, textile material and daily commodities) were dominant in the BS, while maritime activities (fishing and mariculture) were the main source of MPs in the YS. The mass balance model revealed that the total MP input and output to the BS and the YS was 3396.92 t yr^-1 and 3814.81 t yr^-1, respectively. The major input pathway of MPs to the BS and the YS were river discharge and air deposition, respectively. Notably, 94% of MPs in the BS and the YS were deposited to sediments. This study revealed that BS and YS sediments play an important role in preventing MPs from being further transported to the Pacific Ocean, thus more attention should be paid to local ecological risk assessment.

Micro-Nano Plastic in the Aquatic Environment: Methodological Problems and Challenges

Microplastic research has become a buzz word. It is seen as one of the most pressing issues of Anthropocene contamination. There is certainly no doubt about the ubiquitous presence of microplastic (MP) in almost all environmental matrices. However, the validity of considering them as a vector for contaminants needs some reconsideration, there are other more potent pathways. Their effect on marine biota also calls for some realistic experiments with environmental concentrations of MP and nanoplastic (NP). It has been observed that in most published literature, polymer characterization is performed. Is it necessary to do, or will merely finding and confirming the particle as plastic suffice for environmental research? Harmonization of protocols is necessary, and there is likely a need for some inter-laboratory comparison exercises in order to produce comparable data and reliable assessments across regions. Samples collected from the same area using different techniques show an order of magnitude difference in MP concentration. The issue of nanoplastic is more contentious; are we technologically ready to identify NP in environmental samples?

Interactions of microplastics, antibiotics and antibiotic resistant genes within WWTPs

Microplastics (MPs) have been detected in atmosphere, soil, and water and have been characterized as contaminants of emerging concern. When exposed to these environments, MPs interact with the chemical compounds as well as the (micro)organisms inhabiting these ecosystems. This paper overviews the interactions and significant factors influencing the sorption process of antibiotics on MPs since distinct interactions are developed between MPs and antibiotics. The interplay between the MPs and the antibiotic resistant genes (ARGs) microbial hosts is presented and the important factors that may shape the plastisphere resistome are discussed. The interactions of MPs, antibiotics and antibiotic resistant bacteria (ARB) and ARGs in wastewater treatment plants (WWTPs) were discussed with the aim to provide a perspective for better understanding of the role of WWTPs in bringing together MPs, antibiotics and ARB/ARGs and further as release points of MPs carrying antibiotics, and ARB/ARGs.

On the way to reduce marine microplastics pollution. Research landscape of psychosocial drivers

Current human lifestyle generates enormous amounts of plastics and microplastics that end in the ocean and threaten marine life. Exposure to microplastics seems to threaten human health too. Although the degree of damage is not clear yet, precautionary approach urgently requires a change of societal habits. The objective of this study was to discover emerging issues of priority for psychosocial investigation. For this we have compared the landscape research of Reviews with that of Perspectives articles of the last decade, to identify mismatches that unravel still understudied subjects. Results revealed that circular economy is a focus in Perspectives but is not main topic of current psychosocial research. Regarding the actors involved in the change towards circular economy, although companies are priority in Perspectives current research is focused on consumers. Results suggest the need for more efforts on the investigation of corporative responsibility in the way to stop microplastics pollution.

Moving forward in microplastic research: A Norwegian perspective

Given the increasing attention on the occurrence of microplastics in the environment, and the potential environmental threats they pose, there is a need for researchers to move quickly from basic understanding to applied science that supports decision makers in finding feasible mitigation measures and solutions. At the same time, they must provide sufficient, accurate and clear information to the media, public and other relevant groups (e.g., NGOs). Key requirements include systematic and coordinated research efforts to enable evidence-based decision making and to develop efficient policy measures on all scales (national, regional and global). To achieve this, collaboration between key actors is essential and should include researchers from multiple disciplines, policymakers, authorities, civil and industry organizations, and the public. This further requires clear and informative communication processes, and open and continuous dialogues between all actors. Cross-discipline dialogues between researchers should focus on scientific quality and harmonization, defining and accurately communicating the state of knowledge, and prioritization of topics that are critical for both research and policy, with the common goal to establish and update action plans for holistic benefit. In Norway, cross-sectoral collaboration has been fundamental in supporting the national strategy to address plastic pollution. Researchers, stakeholders and the environmental authorities have come together to exchange knowledge, identify knowledge gaps, and set targeted and feasible measures to tackle one of the most challenging aspects of plastic pollution: microplastic. In this article, we present a Norwegian perspective on the state of knowledge on microplastic research efforts. Norway's involvement in international efforts to combat plastic pollution aims at serving as an example of how key actors can collaborate synergistically to share knowledge, address shortcomings, and outline ways forward to address environmental challenges.

Co-production of future scenarios of policy action plans in a science-policy-industry interface - The case of microfibre pollution from waste water treatment plants in Norway

One of the ambitions of the UN Decade of Ocean Science is stakeholder interaction to co-produce new ideas and solutions for policy action plans to ensure that environmental challenges are mitigated in a timely manner. Regulations around the release of microfibres are largely lacking, and we are at an excellent point of departure to test integrative methods of such co-production. We co-designed conceptual maps and Bayesian Belief Networks with probabilistic future scenarios within both inter- and intra-sectoral workshops with industry and scientific stakeholders to gain comparable results of policy action scenarios for curbing the challenge of microfibre pollution within this context. We found that when scientists worked on this alone, their focus was different than when working together with industry directly. Scientists focused on methods for avoiding release into the environment from a technical vantage point, whereas industry emphasized regulatory requirements needed to avoid ambiguity within the sector.

Aging microplastics in wastewater pipeline networks and treatment processes: Physicochemical characteristics and Cd adsorption

Despite a wealth of information on removal of the microplastics (MPs) in wastewater treatment plants (WWTPs), little attention has been paid to how wastewater treatment process affect the MP physicochemical and adsorption characteristics. In this study, changes in physicochemical property of three MPs, i.e. polyamide (PA), polyethylene (PE) and polystyrene (PS) through the wastewater pipeline, grit and biological aeration tanks were investigated. The results show that compared with virgin MPs, the treated MPs have higher specific surface area and O content, and lower C and H contents, and glass transition temperature, implying that the three treatments cause the chain scission and oxidation of the MPs. Cd adsorption capacities of the MPs are higher than the corresponding virgin MPs after sulfidation in the pipeline (SWPN) and biological treatment in aeration tank (BTAT). Pearson correlation analysis shows that the increase is mainly resulted from the enhancement of the O-containing groups on the MPs. However, Cd adsorption capacities of the MPs decrease after mechanical abrasion in grit tank (MAGT), corresponding to the decrease in carbonyl index. Two dimensional FTIR correlation spectroscopy demonstrates that the NH bond in the PA plays a more important role than CH bond in the adsorption of Cd, but only change of the CH bond is found in the PE and PS. The findings provide new insights into the effect of WWTPs on the MP aging and physicochemical characteristics.

Jellyfishing in Europe: Current Status, Knowledge Gaps, and Future Directions towards a Sustainable Practice

Jellyfish are often described as a nuisance species, but as our understanding shifts to more ecosystem-based conceptions, they are also recognized as both important components of marine ecosystems and a resource for humans. Here, we describe global jellyfish fisheries and review production, fishing methods, and applications based on the existing literature. We then focus on future development of a European jellyfish fishery based on current and recent EU research initiatives. Jellyfish have been a staple food in East Asia for eons and now show a potential for non-food applications as well. The main fishing methods are mostly traditional, with set-nets, driftnets, hand-nets, and scoop-nets utilizing small crafts or beach-seines. All require a lot of manual labor, thus providing vital, albeit seasonal, occupation to weaker populations. Larger commercial vessels such as purse seines and trawlers are newly introduced métiers which may enable a larger catch per unit effort and total catch, but pose questions of selectivity, bycatch, vessel stability, and transshipment. Social concerns arising from the seasonality of jellyfish fisheries must be met in SE Asia, Latin America, and in any location where new fisheries are established. In the EU, we recognize at least 15 species showing potential for commercial harvesting, but as of 2021, a commercial fishery has yet to be developed; as in finfish fisheries, we advise caution and recognition of the role of jellyfish in marine ecosystems in doing so. Sustainable harvesting techniques and practices must be developed and implemented for a viable practice to emerge, and social and ecological needs must also be incorporated into the management plan. Once established, the catch, effort, and stock status must be monitored, regulated, and properly reported to FAO by countries seeking a viable jellyfish fishery. In the near future, novel applications for jellyfish will offer added value and new markets for this traditional resource.

Microplastics in aquatic environment: Challenges and perspectives

The occurrence of microplastics in the aquatic environment has become a growing concern globally. Microplastics pose a hazard to the ecological system, and their presence, particularly in the water, has an adverse impact on human health and the ecosystem. Microplastics are released into the environment directly from everyday used plastic items, degradation of plastics, industries, and wastewater treatment plants. Once these contaminants enter the water, aquatic life feeds on them, and microplastics enter the food chain and cause severe health hazards. An assessment of microplastics' ecological risks is essential; however, it is challenging in the present scenario due to limited information available. To fill these knowledge gaps, this paper comprehensively reviews the sources and transport of microplastics in the water environment and their environmental and health effects, global policy frameworks, analytical techniques for microplastic detection, and control strategies to prevent microplastics release in the aquatic environment.

Agricultural Use of Sewage Sludge as a Threat of Microplastic (MP) Spread in the Environment and the Role of Governance

Sewage sludge from wastewater treatment plants is commonly used as a soil amendment on agricultural land. Unfortunately, more and more research indicates that large amounts of microplastic (MP) are re-introduced to soil with sludge. This study aims to present the impact MP has on soil ecosystems, global trends in agricultural sludge management resulting from a high concentration of micropollutants in sludge, and finally propose a high-level strategy for sustainable sludge management. This strategy is mostly dedicated to the European Union and involves multiple stakeholders and the links between each of them to achieve appropriate sludge management to avoid soil pollution with MP. Governance, Technology, Consumer Acceptance, and Economy and Commercial Viability is explored in depth. To the author’s knowledge, this is the first paper to discuss these topics in the context of a changing agricultural scene and identifies ways of which sewage sludge can limit MP pollution whilst still fitting into a circular economy. As total elimination of agriculturally used sludge is not a viable option, more stringent regulation on sludge quality before its use is necessary, especially on contaminant concentrations. This includes MPs limits, to improve sludge quality, in turn improving soil health. More alternative management options for sludge that does not meet land usage requirements are necessary and will be explored in this study. Overall, the combination of factors discussed will inevitably lead to more emphasis on sewage sludge management, therefore it can be expected that the information presented in this review will be of high demand and importance for sludge producers and serves as a comprehensive foundation for researchers to build off.

The Py - GC-TOF-MS analysis and characterization of microplastics (MPs) in a wastewater treatment plant in Gauteng Province, South Africa

Wastewater treatment plants (WWTPs) in South Africa, like is the case for most WWTPs around the globe albeit capable of removing substantial quantities of microplastics (MPs) and in fact, the treatments become ineffective for those plastic particles less than 100 µm. As a consequence, the receiving water bodies in which the final effluent is discharged becomes highly polluted. The present research is devoted to the analysis of the pervasive MPs in wastewaters of the treatment plant located in the Gauteng Province, South Africa using Pyrolysis - GC-TOF-MS. Based on the results, there were 23 pyrolyzate products with contributions from PVC, PA, PET and PE with abundances of 47.8%, 13.1%, 17.4% and 4.3% respectively. The remaining 17.4% could be attributed as additives in MPs. The SEM images illustrated that the MPs appeared to be inter - wined, fibrous of different thicknesses and lengths. The highly weathered MPs exhibited the rough surface which was noticeably damaged with peeled off layers presumably because of photo-oxidation during the aging process. The vibrational modes of FTIR revealed the presence of the various functional groups in the corresponding polymers of MPs. The thermal studies confirmed the presence of calcium, aluminum and silicon as residues of catalysts or flame retardants or UV stabilizers in MPs or as adsorbates resulting from the surface adsorption from the surroundings. The Py-GC-TOF-MS confirmed the identity of the various fragments related to the MPs monomers.

Differences in removal rates of virgin/decayed microplastics, viruses, activated carbon, and kaolin/montmorillonite clay particles by coagulation, flocculation, sedimentation, and rapid sand filtration during water treatment

One of the main purposes of drinking water treatment is to reduce turbidity originating from clay particles. Relatively little is known about the removal of other types of particles, including conventionally sized powdered activated carbon (PAC) and superfine PAC (SPAC), which are intentionally added during the treatment process; microplastic particles; and viruses. To address this knowledge gap, we conducted a preliminary investigation in full-scale water treatment plants and then studied the removal of these particles during coagulation-flocculation, sedimentation, and rapid sand filtration (CSF) in bench-scale experiments in which these particles were present together. Numbers of all target particles were greatly decreased by coagulation-flocculation and sedimentation (CS). Subsequent rapid sand filtration greatly reduced the concentrations of PAC and SPAC but not the concentrations of viruses, microplastic particles, and clay particles. Overall removal rates by CSF were 4.6 logs for PAC and SPAC, 3.5 logs for viruses, 2.9 logs for microplastics, and 2.8 logs for clay. The differences in removals were not explained by particle sizes or zeta potentials. However, for clays, PAC and SPAC, for which the particle size distributions were wide, smaller particles were less efficiently removed. The ratios of both clay to PAC and clay to SPAC particles increased greatly after rapid sand filtration because removal rates of PAC and SPAC particles were about 2 logs higher than removal rates of clay particles. The trend of greater reduction of PAC concentrations than turbidity was confirmed by measurements made in 14 full-scale water purification plants in which residual concentrations of PAC in treated water were very low, 40-200 particles/mL. Clay particles therefore accounted for most of the turbidity in sand filtrate, even though PAC was employed. The removal rate of microplastic particles was comparable to that of clays. Sufficient turbidity removal would therefore provide comparable removal of microplastics. We investigated the effect of mechanical/photochemical weathering on the removal of microplastics via CSF. Photochemical weathering caused a small increment in the removal rate of microplastics during CS but a small reduction in the removal rate of microplastics during rapid sand filtration; mechanical weathering decreased the removal rate via CS but increased the removal rate via rapid sand filtration. The changes of removal of microplastics might have been caused by changes of their zeta potential.

Microplastic contamination and fluxes in a touristic area at the SE Gulf of California

Microplastics (MPs) are long-lasting anthropogenic pollutants, observed in all types of natural environments. The MPs abundance and their temporal variability in beach sands, surface waters (manta trawl), and suspended sediments (sediment trap) were assessed in Mazatlán, Mexico, a tourism destination on the northern Pacific coast, under the hypothesis that MP contamination is influenced by rainfall and population density. The MP concentrations in beach sands from urban and rural areas nearby Mazatlán (4-36 MPs m^-2) and in surface waters (1.7-2.0 MPs m^-3) were comparable between type of sampling sites; whereas the MP fluxes in sediment trap samples varied widely (40-782 MPs m^-2 day^-1) with highest values during the rainfall season. The MPs recovered were mostly white/clear (48-54%), and the prevailing shapes were fragments in beach sands and surface waters (59-80%), and fibers (75%) in suspended sediments. The synthetic polymers polypropylene, polyethylene, and polyethylene terephthalate were the most abundant in the study area.