Sorption and release process of polybrominated diphenyl ethers (PBDEs) from different composition microplastics in aqueous medium: Solubility parameter approach

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.

Spatial distribution and vertical characteristics of microplastics in the urban river: The case of Qinhuai River in Nanjing, China

Microplastics (MPs) are emerging as global environmental pollutants, significantly influencing the safety of city rivers. This study investigated six sampling sites in the Qinhuai River of Nanjing, which explored the distribution and characteristics of MPs and the microbial structure in 2023. The studied river contained various levels of MPs with average concentrations of 667.68 items/L, whose abundance firstly decreased midstream and then increased downstream. The MPs abundance upstream was higher in surface water column, microplastics midstream and downstream accumulated more in deep water column. Black and blue are prevalent in the color distribution, while the polymers of PC, PP and PS changed with increasing depth, with a proportion of 74 % ∼ 97 % in the dominant shapes of granules. Furthermore, the water with higher MPs may stimulate the growth of MPs-related bacteria in sediments, including the genus of Pseudoxanthomonas and Dechloromonas. Our research will provide constructive support for enhancing urban river management strategies.

Fabrication of magnetic Fe3O4 doped β-cyclodextrin microporous organic network for the efficient extraction of endocrine disrupting chemicals from food takeaway boxes

Endocrine disrupting chemicals (EDCs) are a typical class of natural or man-made endogenous hormone agonists or antagonists that can directly or potentially interfere with human endocrine system. However, it is still difficult to analyze trace EDCs directly from complex environment and food matrices. Therefore, the proper sample pretreatment is highly desired and the preparation of efficient adsorbents is of great challenge and importance. Herein, we report the facile one-pot solvothermal synthesis of Fe3O4 nanoparticle doped magnetic β-cyclodextrin microporous organic network composites (MCD-MONs) for the magnetic solid phase extraction (MSPE) of four phenolic EDCs in water and food takeaway boxes prior to the high-performance liquid chromatography analysis. The sheet-like Fe3O4 doped MCD-MONs offered good magnetic property (16.5 emu g-1) and stability, and provided numerous hydrogen bonding, hydrophobic, π-π, and host-guest interaction sites for EDCs. Under the optimal experimental conditions, the established method was successfully verified with wide linear range (2.0-1000 µg L-1), low limits of detection (0.6-1.0 µg L-1), good precisions (intra-day and inter-day RSDs < 5.2 %, n = 3), large enrichment factors (88-98) and adsorption capacity (90.3-255.8 mg g-1), short extraction time (6 min), less adsorbent consumption (3 mg), and good reusability (at least 8 times) for EDCs. The proposed method was successfully applied to detect the trace EDCs in real samples with the recovery of 84.0-99.7 %. This work demonstrated the great potential of MCD-MONs for the efficient MSPE of trace EDCs from complex food takeaway boxes and water samples and uncovered the prospect of CD-based MONs in sample pretreatment.

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.

Development of a solubility parameter calculation-based method as a complementary tool to traditional techniques for indoor dust microplastic determination and risk assessment

Herein, a method based on solubility parameter calculation was first used to analyze microplastics in indoor dust. The limit of quantification (LOQ) reached 0.2 mg/g, and the result of reference material SRM 2585 (n = 3) was 14.8 mg/g ± 1.8 %, suggesting satisfying sensitivity and precision. Recoveries of spiking experiments were > 80 % with no obvious matrix interferences observed, except ethylene propylene diene monomer (EPDM) MPs. Further, 69 indoor dust samples were analyzed to verify the method and to assess exposure scenarios for graduate students in Tianjin, China. EPDM was identified in an indoor environment for the first time as the second most widely detected type after PET in this work. The mass-based result is complementary to the outcomes from thermogravimetric analysis-gas chromatography-mass spectrometry and laser direct infrared imaging. Significant correlations were found between total organic carbon (TOC), microplastics, and BDE-209 concentrations, indicating microplastics important contaminant vectors in indoor dust. Dormitory stays and PET contributed the most to health risks among the three exposure scenarios and detected four polymers, respectively. This work provides an approach with the potential for the standardized determination of microplastics in complex environmental matrices and reveals exposure characteristics of indoor dust microplastics.

Change in the chemical, mechanical and physical properties of plastics due to UVA degradation in different water matrices: A study on the recyclability of littered plastics

To move towards a circular society, the recyclability potential of littered plastics should be explored to provide potential value for a product that is typically destined for landfill or incineration. This study aims to understand the changes in physical, mechanical, and chemical properties of four types of plastics (polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC) and polylactic acid (PLA) after simulated environmental degradation. Plastic samples were subjected to different water matrices (in an attempt to simulate terrestrial, ocean, and river environments) to understand the role the environment plays on plastic degradation. Significant physical, mechanical, and chemical changes were observed for the PET, PP and PLA samples. Flakes and cracks were noted during the scanning electron microscopy (SEM) analysis of PET, PP and PLA illustrating the surface degradation that had occurred. Colour scanning of the samples provided complementary information about their suitability for upcycling or downcycling. Both PET and PP had visual colour changes, making them unsuitable for upcycling purposes. PLA had a significant decrease in its tensile strength in all environmental conditions, alongside significant chemical and surface change as revealed by Fourier-transform infrared (FTIR) and SEM analysis, respectively. PC had little to no changes in its chemical, mechanical, and physical properties due to high resistance to solar (UVA) degradation in presence of salt and natural organic matter in the form of humic acid. Therefore, out of the four types of plastics tested, PC was the only plastic determined to have good upcycling potential if collected from the environment. However, PET and PP could still be recycled into lower value products (i.e., construction materials).

The spatial distribution and abundance of microplastics in lake waters and ice during ice-free and ice-covered periods

Understanding the spatial distribution and characteristics of microplastics (MPs) in lake waters is essential to assessing and addressing lacustrine MP pollution. This study investigated how lake ice affects the abundance, spatial distribution, and characteristics (size, shape) of MPs in Lake Ulansuhai by analyzing samples collected at ten sites uniformly distributed throughout the lake during ice-free and ice-covered periods. The abundance of MPs ranged between 204 ± 28 and 1224 ± 185 n·L^-1 in lake waters during the ice-free period, and from 34 ± 8 to 216 ± 21 n·L^-1 and 269 ± 84 to 915 ± 117 n·L^-1 in water and ice during the ice-covered period, respectively. During the ice-covered period, MPs were 2.74-8.14 times higher in the ice than in water beneath the ice. Ice formation decreased MP abundance in lake waters, in part, by incorporating a relatively high percentage of MPs into the ice mass during freezing and by inhibiting atmospheric MPs from reaching the lake waters. The abundance of MPs in the water during the ice-free period was 4.50-11.30 times greater than during the ice-covered period. Seasonal variations in MP shape also occurred; the proportion of fibrous MPs in water decreased during the ice-covered period. Variations in MP abundance were partly due to differences in sedimentation rates; the settling of fibrous MPs is slower, making it easier for them to be captured during the formation of surface ice. Spatially, MPs were uniformly distributed during the ice-free period, but exhibited a spatially distinct pattern during ice-covered periods, when MPs in lake waters were higher in the northeast and lower in the southwest portions of the lake. During the ice-free period, small MPs (0.05-0.5 mm) were more likely to move with currents in the lake, whereas water velocities were reduced by ice formation, allowing small MPs to accumulate near the lake inlet.

Antibiotic sorption onto microplastics in water: A critical review of the factors, mechanisms and implications

Microplastics as vectors for contaminants in the environment is becoming a topic of public interest. Microplastics have been found to actively adsorb heavy metals, per-fluorinated alkyl substances (PFAS), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceuticals and personal care products (PPCPs) and polybrominated diethers (PBDs) onto their surface. Particular interest in microplastics capacity to adsorb antibiotics needs further attention due to the potential role this interaction plays on antibiotic resistance. Antibiotic sorption experiments have been documented in the literature, but the data has not yet been critically reviewed. This review aims to comprehensively assess the factors that affect antibiotic sorption onto microplastics. It is recognised that the physico- chemical properties of the polymers, the antibiotic chemical properties, and the properties of the solution all play a crucial role in the antibiotic sorption capacity of microplastics. Weathering of microplastics was found to increase the antibiotic sorption capacity by up to 171%. An increase in solution salinity was found to decrease the sorption of antibiotics onto microplastics, in some instances by 100%. pH also has a substantial effect on sorption capacity, illustrating the significance of electrostatic interactions on the sorption of antibiotics onto microplastics. The need for a uniform experimental design when testing antibiotic sorption is highlighted to remove inconsistencies in the data currently presented. Current literature examines the link between antibiotic sorption and antibiotic resistance, however, further studies are still required to fully understand this emerging global crisis.

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.

Sorption and desorption of bisphenols on commercial plastics and the effect of UV aging

Plastics gradually degrade in the natural environment from the effect of irradiation, which can change the surface properties of plastics and affect the migration behaviour of pollutants. Up to now, studies on the sorption/desorption behaviour of organic pollutants on aged plastics are still limited. In this study, several types of commercial plastics (polyurethane (PU), polyamide (PA), polyvinyl chloride (PVC), expanded polystyrene (EPS)) were selected to investigate the sorption and release behaviour for four kinds of bisphenols (bisphenol-F, A, B, AP). The results from Raman spectroscopy and scanning electron microscopy (SEM) analysis showed evidence of oxidization and surface cracks of plastics after irradiation. The sorption behaviour for both fresh and aged plastics were dominated by hydrophobicity. In addition, the electrostatic force, H-bonding interaction, and π-π interaction were also the important factors impacting the sorption process. The desorption kinetics behaviour indicates that desorption becomes faster after aging. Hydrophobicity is also an important factor that affects desorption behaviour. This study showed that sorption capacity for most fresh and aged plastics was enhanced by the impact of salinity and dissolved organic matter (DOM). Increased temperature could increase the desorption of bisphenols on both fresh and aged plastics, which illustrated that warm environments would promote more pollutants be released from plastics to water bodies.

Microplastics in the environment: Recent developments in characteristic, occurrence, identification and ecological risk

Microplastics (MPs) are developing as persistent pollutants that are causing significant concern in terms of environmental health. A microplastic is a particle of plastic that is less than 5 mm in diameter, which has penetrated and harmed the environment. MPs have been the subject of numerous analyses, including several adverse assessments; however, most of these studies have focused on their presence in coastal environments. The current state of knowledge regarding the characteristics, occurrences, and potential impact of MPs in the terrestrial ecosystem is incomplete. The goal of this study is to undertake a thorough review of existing knowledge and scientific publications on MP occurrences in the environment, their fate and mobility, and their consequences, as well as to explore such discoveries. MPs have been elaborately discussed in this review in terms of their occurrences, features, and origins in the oceans, freshwater, sediments, soils, and the atmosphere, along with the data obtained from experiments and models on the fate and mobility of MPs in the environment. This paper also includes research data on the environmental toxicity, bioavailability, and bioaccumulation of MPs.

Microplastics in the Gulf of Mexico: A Bird’s Eye View

Microplastic debris is a persistent, ubiquitous global pollutant in oceans, estuaries, and freshwater systems. Some of the highest reported concentrations of microplastics, globally, are in the Gulf of Mexico (GoM), which is home to the majority of plastic manufacturers in the United States. A comprehensive understanding of the risk microplastics pose to wildlife is critical to the development of scientifically sound mitigation and policy initiatives. In this review, we synthesize existing knowledge of microplastic debris in the Gulf of Mexico and its effects on birds and make recommendations for further research. The current state of knowledge suggests that microplastics are widespread in the marine environment, come from known sources, and have the potential to be a major ecotoxicological concern for wild birds, especially in areas of high concentration such as the GoM. However, data for GoM birds are currently lacking regarding typical microplastic ingestion rates uptake of chemicals associated with plastics by avian tissues; and physiological, behavioral, and fitness consequences of microplastic ingestion. Filling these knowledge gaps is essential to understand the hazard microplastics pose to wild birds, and to the creation of effective policy actions and widespread mitigation measures to curb this emerging threat to wildlife.

PBDEs in the marine environment: Sources, pathways and the role of microplastics

Brominated flame retardants (BFRs) are an important group of additives in plastics that increase resistance to ignition and slow down the rate of burning. Because of concerns about their environmental and human health impacts, however, some of the most widely employed BFRs, including hexabromocyclododecane (HBCD) and commercial mixtures of penta-, octa- and deca- (poly)bromodiphenyl ethers (PBDEs), have been restricted or phased out. In this review, the oceanic sources and pathways of PBDEs, the most widely used BFRs, are evaluated and quantified, with particular focus on emissions due to migration from plastics into the atmosphere versus emissions associated with the input of retarded or contaminated plastics themselves. Calculations based on available measurements of PBDEs in the environment suggest that 3.5 and 135 tonnes of PBDEs are annually deposited in the ocean when scavenged by aerosols and through air-water gas exchange, respectively, with rivers contributing a further ∼40 tonnes. Calculations based on PBDE migration from plastic products in use or awaiting or undergoing disposal yield similar net inputs to the ocean but indicate a relatively rapid decline over the next two decades in association with the reduction in the production and recycling of these chemicals. Estimates associated with the input of PBDEs to the ocean when "bound" to marine plastics and microplastics range from about 360 to 950 tonnes per year based on the annual production of plastics and PBDEs over the past decade, and from about 20 to 50 tonnes per annum based on the abundance and distribution of PBDEs in marine plastic litter. Because of the persistence and pervasiveness of plastics in the ocean and diffusion coefficients for PBDEs on the order of 10^-20 to 10^-27 m² s^-1, microplastics are likely to act as a long-term source of these chemicals though gradual migration. Locally, however, and more important from an ecotoxicological perspective, PBDE migration may be significantly enhanced when physically and chemically weathered microplastics are exposed to the oily digestive fluids conditions of fish and seabirds.

Enhanced propagation of intracellular and extracellular antibiotic resistance genes in municipal wastewater by microplastics

Microplastics (MPs) are an emerging global concern as they are abundant in the environment and can act as vectors of various contaminants. However, whether and how MPs can be vectors of antibiotic resistance genes (ARGs), especially extracellular ARGs (eARGs), remains far from explicit. This study addresses the adsorption of both intracellular ARGs (iARGs) and eARGs by four types of MPs in municipal wastewater, and then explores the potential horizontal gene transfer of iARGs and eARGs exposed to MPs. Results indicate that though MPs significantly adsorbed both iARGs and eARGs, eARGs were adsorbed with a significantly higher fold enrichment (2.0-5.0 log versus 2.0-3.3 log) and rate (0.0056 min^-1 versus 0.0037 min^-1) than iARGs. While all four types of MPs adsorbed ARGs, polypropylene MPs showed the highest adsorption capacity for ARGs. Background constituents such as humic acid and antibiotics significantly inhibited adsorption of iARGs, but not eARGs on MPs. The presence of sodium chloride didn't significantly affect adsorption of iARGs or eARGs. The adsorption of ARGs was well explained by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) interaction energy profile. Higher eARG adsorption was attributed to a lower energy barrier between MPs and eARGs than that between MPs and iARGs. Exposure to MPs enhanced horizontal gene transfer of both iARGs and eARGs by 1.5 and 2.0 times, respectively. The improved contact potential between donors and recipients, as well as the increased cell permeability of recipients induced the improved horizontal gene transfer by MPs. This study underscores the need to address ARG propagation through adsorption to MPs.

Calculation and Experimental Validation of a Novel Approach Using Solubility Parameters as Indicators for the Extraction of Additives in Plastics

Accurately quantifying chemical additives with adverse health effects in plastic products is critical for environmental safety and risk assessment. In this work, a novel approach using solubility parameters (δ) as indicators for the extraction of additives in plastics was developed. The mechanism was evaluated by using 10 organic solvents with different solubility parameters to extract brominated flame-retardant-decabrominated diphenyl ether (BDE-209) in polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Certified reference materials (CRMs) or CRM candidate materials were applied as matrix materials. The extracted BDE-209 and solubility parameters of solvents could fit into a curve of a quadratic function. The value of abscissa corresponding to the vertex of the function was close to the solubility parameter of plastic calculated by the group contribution method (Δδ < 0.37). Toluene, n-hexane, and acetone were the solvents with high extraction efficiency for PE, PP, and PET, confirming the feasibility of the developed approach. The results of ethyl acetate and acetone indicated the high weight of functional groups affecting the dissolution behavior. The developed approach was further verified by analyzing penta-/octa-BDE and phthalate esters in PET and polyvinyl chloride (PVC) and finally applied to analyze 15 plastic products made of PP, PE, PET, polystyrene, and PVC. The detected tetrabromodiphenyl ether (BDE-47), BDE-209, decabromodiphenyl ethane, and di(2-ethylhexyl) terephthalate all matched the approach and verified its practicability for field sample analysis.

Environmental profile, distributions and potential sources of halogenated polycyclic aromatic hydrocarbons

Halogenated polycyclic aromatic hydrocarbons (HPAHs) are high lipophilic and degradation-resistant, which have been detected in the air, water, sediment and biota. HPAHs tend to have strong adverse effects on animals and humans. Although we have realized HPAHs are emerging contaminants which needs to be paid attention, there is still a lack of their individual commercial standards. This makes it difficult for understanding HPAHs comprehensively. This review is devoted to collect all the results have reported, and give a systemic look of their global distributions, influence factors and sources. Compared with air, studies on other environmental matrices (water and sediment) are more limited. The researches on organisms are fewest. Comparing the studied congeners, there are more studies on ClPAHs than BrPAHs. Human activities contribute mostly to their occurrence. Further, we then also introduce the toxicity and analytical methods to better understand HPAHs. The future research directions are also provided. Through this review, we can conclude there is an urgent need to develop analysis methods and ecologic risk assessment for better exploring HPAHs. Effective methods should be done to control HPAHs. Therefore, this review can provide a good basis for researchers to understand and control global pollution.

The toxic impacts of microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) on haematic parameters in a marine bivalve species and their potential mechanisms of action

Microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) are universally detected in the marine ecosystem and may exert adverse impacts on marine species. Although under realistic pollution scenarios, PAH pollution usually occurs as a mixture of different PAH compounds, the toxic impacts of PAH mixtures on marine organisms remain largely unknown to date, including their interactions with other emergent pollutants such as MPs. In this study, the single and combined toxic impacts of polystyrene MPs and a mixture of PAHs (standard mix of 16 representative PAHs) on haematic parameters were evaluated in the blood clam Tegillarca granosa. Our data demonstrated that blood clams treated with the pollutants examined led to decreased total haemocyte count (THC), changed haematic composition, and inhibited phagocytosis of haemocytes. Further analyses indicated that MPs and a mixture of PAHs may exert toxic impacts on haematic parameters by elevating the intracellular contents of reactive oxygen species (ROS), giving rise to lipid peroxidation (LPO) and DNA damage, reducing the viability of haemocytes, and disrupting important molecular signalling pathways (indicated by significantly altered expressions of key genes). In addition, compared to clams treated with a single type of pollutant, coexposure to MPs and a mixture of PAHs exerted more severe adverse impacts on all the parameters investigated, indicating a significant synergistic effect of MPs and PAHs.

PAH and POP Presence in Plastic Waste and Recyclates: State of the Art

The presence of different pollutants in recycled plastics is reviewed in this article. The desirable circular economy of plastics should be linked to the availability of clean recycled plastics with a non-significant and small to nil amount of substances of concern. Different researchers found polycyclic aromatic hydrocarbons (PAHs) and Persistent Organic Pollutants (POPs), such as brominated flame retardants (BFRs), pesticides, dioxins and furans (PCDD/Fs and PBDD/Fs) in plastic recyclates. This represents an added difficulty to the effective recycling process of plastics that reduces the demand for energy and materials, in addition to posing a great environmental danger since they represent a vector of accumulation of the contaminants that will finally appear in the most unexpected products. Life Cycle Analysis of the plastic wastes recycling process indicates a great saving of energy, water and CO2 emissions.

Environmental fate, ecotoxicity biomarkers, and potential health effects of micro- and nano-scale plastic contamination

In recent decades, the quantity of plastic waste products has increased tremendously. As plastic wastes are released into the environment, they exert harmful effects on biota and human health. In this work, a comprehensive review is offered to describe the physical and chemical characteristics of microplastics and nanoplastics in relation to their fate, microbial ecology, transport, and ecotoxic behavior. Present discussion is expanded further to cover the biochemical, physiological, and molecular mechanisms controlling the environmental fate, ecotoxicity, and human health hazards of micro- and nanoplastics. The risks of their exposure to microbes, plants, animals, and human health are also reviewed with special emphasis. Finally, a direction for future interdisciplinary research in materials and polymer science is also discussed to help control the pollution caused by micro- and nanoplastics.

A review of the removal of microplastics in global wastewater treatment plants: Characteristics and mechanisms

Wastewater treatment plants (WWTPs) are considered to be the main sources of microplastic contaminants in the aquatic environment, and an in-depth understanding of the behavior of microplastics among the critical treatment technologies in WWTPs is urgently needed. In this paper, the characteristics and removal of microplastics in 38 WWTPs in 11 countries worldwide were reviewed. The abundance of microplastics in the influent, effluent, and sludge was compared. Then, based on existing data, the removal efficiency of microplastics in critical treatment technologies were compared by quantitative analysis. Particularly, detailed mechanisms of critical treatment technologies including primary settling treatment with flocculation, bioreactor system, advanced oxidation and membrane filtration were discussed. Thereafter, the abundance load and ecological hazard of the microplastics discharged from WWTPs into the aquatic and soil environments were summarized. The abundance of microplastics in the influent ranged from 0.28 particles L^-1 to 3.14 × 10⁴ particles L^-1, while that in the effluent ranged from 0.01 particles L^-1 to 2.97 × 10² particles L^-1. The microplastic abundance in the sludge within the range of 4.40 × 10³-2.40 × 10⁵ particles kg^-1. In addition, there are still 5.00 × 10⁵-1.39 × 10¹⁰ microplastic particles discharged into the aquatic environment each day Moreover, among the critical treatment technologies, the quantitative analysis revealed that filter-based treatment technologies exhibited the best microplastics removal efficiency. Fibers and microplastics with large particle sizes (0.5-5 mm) were easily separated by primary settling. Polyethene and small-particle size microplastics (<0.5 mm) were easily trapped by bacteria in the activated sludge of bioreactor system. The negative impact of microplastics from wastewater treatment plant was worthy of attention. Moreover, unknown transformation products of microplastics and their corresponding toxicity need in-depth research.

Photoassisted degradation of 2,2',4,4'-tetrabrominated diphenyl ether in simulated soil washing system containing Triton X series surfactants

This study aims to use ultraviolet (UV) irradiation to decompose polybrominated diphenyl ethers (PBDEs) in the elutes and then reuse the surfactants. The results indicate that UV can remove 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) from surfactant eluents and Triton X series surfactants also can remove BDE-47 from the soil. Triton X-100 (TX-100) is the most promising surfactant during the washing and photodegradation processes. Quench experiments suggest that both ¹O₂ and OH• were involved in the TX-100 decomposition but only ¹O₂ is responsible for the degradation of BDE-47. In analysis of the photoproducts of BDE-47 by Gas Chromatography Mass Spectrum (GC-MS) and Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS), BDE-47 was mainly debrominated to the lower-brominated BDEs and then oxidized to ring-opening products. The little loss of TX-100 can mainly be attributed to the breakage of polyethylene oxide (PEO) chain. Nevertheless, the washing wastes treated by UV light can exhibit higher solubility for BDE-47 than before, indicating they can be reused for BDE-47 removal from soil. The toxicity assessment experiments were performed using Escherichia coli (E.coli) as an indicator. The results indicate that the removal of BDE-47 by UV irradiation can reduce the toxicity of eluent.