Performance and mechanism of simultaneous Sb(III) and Cd(II) removal from water by Fe-Mn binary oxide/bone char.

A novel Fe-Mn binary oxide (FMBO)/bone char composite (FMBC) was synthesized and utilized to simultaneously adsorb Sb(III) and Cd(II) from aqueous phase in this study. The successful loading of Fe-Mn binary oxide on the bone char surface was revealed by the results of scanning electron microscope, X-ray diffraction patterns, and energy dispersive spectroscopy of FMBC. The FMBC exhibited remarkable ability of simultaneous removing Sb(III) and Cd(II) from aqueous, and the presence of Cd(II) enhanced Langmuir theoretical maximum adsorption capacity for Sb(III) significantly from 67.8 to 209.0 mg/g. Besides, FMBC could efficiently remove Sb(III) and Cd(II) in the wide initial pH range of 2-7. The influences of ionic strength, co-existing anions, humic acid, and temperature on the adsorption of Sb(III) and Cd(II), and the application potential of FMBC in actual groundwater were investigated. The main mechanisms of Sb(III) and Cd(II) adsorption onto FMBC involved redox, electrostatic interaction, surface complexation, ion exchange, and precipitation. The result of X-ray photoelectron spectroscopy and mapping spectrum analysis revealed that Mn(III) on FMBC played the key role in the Sb(III) oxidation, while FeOOH worked as the adsorption sites of FMBC. Meanwhile, the hydroxyapatite on FMBC also contributed to the removal of Cd(II). The presence of Cd(II) not only increased the positive charge on the surface of FMBC but also formed the Fe-Sb-Cd ternary complex, promoting the removal of Sb. This work provides valuable information for the application of FMBO/bone char as a cost-effective adsorbent to remediate co-pollution of Sb(III) and Cd(II) in aqueous environment.

Mn-MOF derived manganese sulfide as peroxymonosulfate activator for levofloxacin degradation: An electron-transfer dominated and radical/nonradical coupling process.

Recently, transition metal sulfides have attracted much attention due to their better catalytic capacities as peroxymonosulfate (PMS) activator than their metal oxide counterparts. However, the systematic studies on PMS activation using transition metal sulfides are still lacking. In this work, manganese sulfide (MnS) materials were synthesized via a MOFs-derived method and utilized for PMS activation to degrade levofloxacin (LVF) in water for the first time. As expected, MnS exhibited remarkable LVF degradation efficiency by PMS activation, which was distinctly higher than Mn2O3. The results of quenching experiments, electro spin resonance identification and electrochemical tests indicated that electron-transfer progress was the dominant mechanism in α-MnS/PMS system. Meanwhile, the presence of 1O2 and radicals further became the removal of LVF by α-MnS/PMS system into a radical/nonradical coupling process. The superior electrical conductivity of α-MnS than α-Mn2O3 was revealed by DFT calculations, which resulted in the higher catalytic capacity of α-MnS. The result of XPS also indicated the S species in MnS accelerated the recycle of Mn(IV)/Mn(II) and then promoted the generation of radicals. Furthermore, the influence of various environmental conditions on LVF removal and the reusability of α-MnS were also investigated, which demonstrated the high application potential of α-MnS/PMS system. Finally, six possible pathways of LVF oxidation in the system were proposed based on the identified byproducts and their ecotoxicity was evaluated with ECOSAR method. This work promotes the fundamental understanding of PMS activation by α-MnS and provides useful information for practical application of manganese sulfide in water treatment.

Real-time variabilities in microplastic abundance and characteristics of urban surface runoff and sewer overflow in wet weather as impacted by land use and storm factors.

Urban surface runoff (USR) and drainage system overflows during wet weather (WWF) play a key role in shaping water pollution. Particularly, the impact of large amounts of microplastic pollution on urban water bodies is unclear. We conducted an in-field investigation in six central urban drainage systems along Suzhou Creek in the Shanghai megacity of China and identified the impacts of storm factors and land use on the real-time dynamic changes in microplastic abundance and characteristics in USR and WWF. Microplastic abundances ranged from 228.3 ± 105.4-4969.51 ± 348.8, 309.3 ± 144.3-5195.8 ± 425.5, and 130.0 ± 30.0-8500.0 ± 1241.0 particles/L in the traffic and residential catchment USR, and the WWF, respectively. Under similar storm factor conditions, we observed correlations between environmental factors and microplastic abundance, especially the polymer type, verifying the significant role of land use. The microplastic abundance were 90.2 particles/L higher in the traffic catchment USR than in the residential catchment USR. Notably, we found unique microplastic polymers comprising ethylene vinyl acetate copolymer and thermoplastic elastomers in the residential and traffic catchment USR, respectively. However, land use had a minimum impact on the size and shape of microplastics: small-sized and film microplastics dominated in both USR types. We found statistical evidence of the widespread correlations between microplastic abundance and storm factors (accumulated storm depth and WWF flow) in both USR and WWF. The first flush phenomenon of microplastic dynamics was found in both USR and WWF. Microplastic characteristics also changed dynamically with storm time. With heavy storm factors, polypropylene and small-sized (<1 mm) microplastics in USR events increased and then decreased. This was also true for WWF events in granular and polyethylene terephthalate microplastics. Our results can facilitate the targeted mitigation of emerging pollutants to enhance stormwater management strategies and prevent future contamination.

[Ecological Risk Assessment of Microplastics Occurring in Surface Water of Terrestrial Water Systems across China].

To assess the ecological risk of microplastics (MPs) occurring in the surface water of terrestrial water systems across China, this study obtained relevant literature and data by searching keywords including microplastics, urban, and river on websites such as Science Direct and Web of Science. We constructed an evaluation method of ecological risk characterization ratio (RCR) based on chemical hazard data, as well as data of MPs abundance and polymer proportion originating in studies from 2017 to 2021 that covered 33 water bodies in 15 provinces. The results showed that the average abundance of MPs in natural water bodies in China reached (3604.2±5926.4) n·m-3, and the average abundance of MPs in urban water bodies was (7722.6±9505.7) n·m-3. The corresponding average RCR of natural water bodies was 22.09±45.2, and the average RCR of urban water bodies was 15.67±34.8. Therefore, according to the value of RCR, the ecological risk could be rated as four levels. Of these, no significant risk (RCR ≤ 1) was found in 17 water bodies, accounting for 42.5%; low ecological risks (RCR 1-10) were found in 12 water bodies (30%); medium ecological risks (RCR 10-100) were found in 9 water bodies (22.5%); and high ecological risks (RCR>100) were found in 2 water bodies (5%). Data analysis showed a significant correlation between MPs abundance and RCR values in natural water bodies (R2=0.875, P<0.01), though not in urban water bodies. This suggested that the high abundance of MPs could not precisely indicate a high degree of ecological risk in the area. In addition, RCR values were observed to be positively correlated with the watershed area (R2=0.864, P<0.01), and MPs abundance was correlated with GDP (R2=0.679, P<0.05) and watershed resident population (R2=0.922, P<0.05). This study provides baseline data for evaluating the ecological risk of MPs and a feasible method for evaluating the ecological risk of MPs in surface water of terrestrial water systems.

Quantifying microplastic stocks and flows in the urban agglomeration based on the mass balance model and source-pathway-receptor framework: Revealing the role of pollution sources, weather patterns, and environmental management practices.

Microplastics are widely present in global ecosystems, threatening both marine and freshwater species. Given this problem, it is vital to research where land-based microplastics originate and how they are transmitted to receiving waters in urban agglomerations. Research results should inform systemic mitigation efforts to prevent future contamination. This study established the multi-directional transmission network of a microplastic mass balance system using a source-pathway-receptor framework, and involving annual source stocks and pathway flows with considerable variations under dry and wet weather patterns. Details of a baseline scenario quantifying the occurrence and spread of microplastics in an urban agglomeration were also determined in the context of current environmental management practices. We demonstrated that the total stock of the six major pollution sources amounted to 5317.7 ± 2175.3 and 3320.1 ± 953.6 tons/a in dry and wet weather, respectively; and 2347.8 ± 766.9 and 1991.8 ± 701.8 tons/a flows directly entered the sewer system and receiving water in Shanghai, China, respectively. Prominent microplastic stocks were found in atmospheric fallout, industrial wastewater, and domestic sewage. These stocks were much higher compared to crop farming wastewater, aquacultural wastewater, and livestock and poultry breeding wastewater. Total microplastic flows entering receiving water reached 3207.4 ± 1071.6 tons/a; the largest contributions were from wet weather overflow (23.7%), direct atmospheric fallout (21.7%), wastewater treatment plant effluent (14.2%), industrial wastewater (14.1%), and surface runoff (10.4%). Weather patterns led to divergent microplastic transmission pathways and mass flows, revealing a lagging timeline mode and illustrating the basic spatiotemporal features of microplastic contamination in urban agglomerations. Terminal disposal practices retained about two-fifths of the microplastic flows that would have otherwise been transmitted into receiving water. Of these, land surface sweep contributed half of the retained flow. Improvements in WWTP removal efficiency, storm sewage interception rate, industrial wastewater collection rate, and sewer sediment dredge rate could further enhance the systemic benefits.

Atmospheric deposition of microplastics in the megalopolis (Shanghai) during rainy season: Characteristics, influence factors, and source.

Urban areas are the hardest hit by microplastic pollution, and deposition is an important part of microplastic migration and transport in the atmosphere, therefore, the study of microplastics in an urban atmospheric deposition is of great significance. This study aims to investigate the deposition characteristics of atmospheric microplastics in megapolis, to clarify the influence of meteorological and anthropogenic factors, and to analyze the sources of atmospheric microplastics. Six sampling sites in Shanghai were selected to collect atmospheric deposition samples during the rainy season. The mean deposition flux of microplastics was 3261.22 ± 2847.99 P·m-2·d-1 (median: 2559.70 P·m-2·d-1), and the types were mainly polyamide (PA, 27.79 %), polyethylene terephthalate (PET, 27.29 %), polypropylene (PP, 16.95 %), and polyvinyl fluoride (PVF, 12.88 %). The microplastic with the particle size of <1000 µm accounted for 88.23 %, and the shape was mainly fiber (73.55 %). The results of correlation analysis and variance analysis of microplastic characteristics with meteorological and anthropogenic factors (land-use, atmospheric pollutants, and urban indicators) showed that wind and precipitation had effects on deposition flux, size and shape, and were more significant at small scales (individual cities), while at large scales, the population was the main influence of microplastics. Atmospheric microplastics in Shanghai may be dominated by exogenous sources, through a combination of microplastic characteristics, wind and backward trajectories. This study further reveals the fate of urban atmospheric microplastics, which has implications for the study of global microplastic pollution.

Interactions of anthropogenic and terrestrial sources drive the varying trends in molecular chemodiversity profiles of DOM in urban storm runoff, compared to land use patterns.

Variations in land use drive the heterogeneous nature of dissolved organic matter (DOM) in storm runoff. However, in the context of the currently complicated multifactor interactions of urban land use, contamination occurrence, and environmental management, it is unclear how the molecular chemodiversity of storm runoff DOM responds to land use patterns or potential anthropogenic sources. Using Fourier-transform ion cyclotron resonance mass spectrometry, this study evaluated the molecular chemodiversity profiles of DOM in urban storm runoff from different land use and underlying surface pavement combinations. The chemodiversity of suburban forest runoff-associated DOM was characterized by high lignin and tannin abundance, predominance of CHO molecules, less heteroatoms, high molecular mass, and highly unsaturated and aromatic compounds. Urban storm runoff-associated DOM was predominantly characterized by abundant lipids, proteins, and carbohydrates, low-mass molecules, abundant S- and P-bearing heteroatoms, and high saturation. The low conformity of unique molecular features co-occurring across urban land-uses suggests a relatively incohesive pool in the urban storm runoff-associated DOM, i.e., high chemodiversity. The reconstructed source-derived patterns significantly drive the directional trends in DOM of urban storm runoff, oppositely shifting toward high saturation vs. high unsaturation and aromatization features. This demonstrates that unveiling the interactions of anthropogenic and terrestrial sources in order to understand the underlying mechanism is critical for our ability to track and predict the current and future turnover in DOM chemodiversity in storm runoff in the context of the global trend of upgrading urban environment management, following recognition of their probable links with urban land-uses. Underlying surface pavement can hardly superimpose a directional effect to alter the discrepancies in the dominant molecules of each urban land use further. These findings reveal the importance of understanding DOM characteristics at a molecular level and potentially enable targeted control of ecological risks in receiving ecosystems induced by urban storm runoff.

A review of atmospheric microplastics pollution: In-depth sighting of sources, analytical methods, physiognomies, transport and risks.

Micro-sized plastics were first examined for atmospheric environment in 2016. From then on, they have been detected in both indoor and outdoor atmospheric samples, with indoor environments demonstrated as containing a big proportion of these particles. The sparse distribution of these particles, is attributed to their swift and long distance transportation that is mainly eased by their tiny size (1 µm to 5 mm) and low density. Due to ongoing limitation on detectable size, analysis methods together with a lack of standardized sampling and analytical procedures, few studies were conducted on airborne microplastics (MPs). Thus, the facts regarding the occurrence, global spatial distribution, fate, and threats to ecosystem and human health of airborne MPs, are still far from being fully clarified. This literature review is a broad depiction of a state of knowledge on atmospheric MPs. Within it, robust and concise information on the sources, inspection, transport, and threats pertaining to airborne MPs are presented. Particularly, the paper entails some information concerning traffic-generated MPs pollution, which has not been frequently discussed within previously published reports. In addition, this paper has widely unveiled sectors and aspects in need of further attention, with the gaps to be filled pinpointed.

Variable sediment methane production in response to different source-associated sewer sediment types and hydrological patterns: Role of the sediment microbiome.

Production of methane (CH4), an essential anthropogenic greenhouse gas, from municipal sewer sediment is a problem deserving intensive attention. Based on long-term laboratory batch tests in conjunction with 16 s rRNA gene sequencing and metagenomics, this study provides the first detailed assessment of the variable sediment CH4 production in response to different pollution source-associated sewer sediment types and hydrological patterns, while addressing the role of the sediment microbiome. The high CH4-production capability of sanitary sewer sediment is shaped by enriched biologically active substrate and dominated by acetoclastic methanogenesis (genus Methanosaeta). Moreover, it involves syntrophic interactions among fermentation bacteria, hydrogen-producing acetogens and methanogens. Distinct source-associated microbial species, denitrifying bacteria and sulfate-reducing bacteria occur in storm sewer and illicit discharge-associated (IDA) storm sewer sediments. This reveals their insufficient microbial function capabilities to support efficient methanogenesis. Hydrogenotrophic methanogenesis (genus Methanobacterium) prevails in both these sediments. In this context, storm sewer sediment has an extremely low CH4-production capability, while IDA storm sewer sediment still shows significant carbon emission through a possibly unique mechanism. Hydrological connections promote the sewer sediment biodegradability and CH4-production capability. In contrast, hydrological disconnection facilitates the prevalence of acetoclastic methanogenesis, sulfate-reducing enzymes, denitrification enzymes and the sulfur-utilizing chemolithoautotrophic denitrifier, which drastically decreases CH4 production. Turbulent suspension of sediments results in relative stagnation of methanogenesis. This work bridges the knowledge gap and will help to stimulate and guide the resolution of 'bottom-up' system-scale carbon budgets and GHG sources, as well as the target CH4 abatement interventions.

[Pollution Status and Pollution Behavior of Microplastic in Surface Water and Sediment of Urban Rivers].

Rivers have been a subject of great concern in recent years as they have been found to be the critical path for the transmission of microplastics from terrestrial land to the ocean. However, the pollution status of microplastics and their behavior in the surface waters and sediments of urban rivers located in different urban areas remain unclear. In this study, 16 samples of surface water and sediment from eight rivers in the central and suburban areas of Shanghai Megacity were obtained and analyzed. High-speed cameras and Fourier transform infrared spectrometers were used to identify the abundance, size, color, shape, type, and other characteristics of microplastics in these samples. The results showed that the average abundance of microplastics in the surface waters of urban rivers in Shanghai Megacity was (7.5±2.8) pieces·L-1, while the corresponding average abundance in the sediment reached (1575.5±758.4)pieces·kg-1 (wet weight). The abundance of microplastics was found to increase with the decreasing particle diameter. Among which, microplastics with a size of less than 500 µm, as well as the fibrous shape, transparent color, and Polyester composition, have always dominated in the urban rivers in Shanghai megacity. Comparably, microplastics in the sediments were more diverse in their morphology features and polymer compositions. Microplastic pollution in the urban rivers in Shanghai megacity was severe in comparison to that in other urban rivers worldwide. Among various urban rivers, the distribution of microplastics with different morphology features and polymer compositions is greatly influenced by a number of factors including the source (e.g., mainly laundry wastewater, personal care products, and refuse plastic waste), hydrodynamic conditions, and the physical and chemical properties of plastics. Furthermore, the pollution behavior (i.e., source, transmission, and fate) of microplastics occurring in urban rivers is discussed, and the potential impacts of various environmental factors are explained.

[Molecular Chemo-diversity of the Dissolved Organic Matter Occurring in Urban Stormwater Runoff].

Stormwater runoff pollution occurring in urban areas can be a notable threat to the ecological environments of receiving water bodies. Dissolved organic matter (DOM) constitutes the primary type of pollutant in stormwater runoff, and tracking of its components and sources can provide valuable scientific bases for the future abatement of stormwater runoff pollution. In this study, aiming to demonstrate the characteristics and sources of the contained DOM in both pavement runoff (PR) and greenland runoff (GR), we applied ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to analyze the molecular chemo-diversity of their DOM, as well as Spearman rank correlations between the molecular chemo-diversity and water quality indicators including suspended solids (SS), total nitrogen (TN), dissolved organic carbon (DOC), and dissolved lead (Pb). The results show:① When the molecular accumulation reaches a saturated state, the cumulative number of molecules of PR-DOM (12498) is much larger than that of GR-DOM (7015). The molecular distribution of PR-DOM (150-750) is smaller yet more concentrated than that of GR-DOM (150-850). ② According to the molecular composition characterization and Spearman rank correlation analysis, the sources of the components of PR-DOM and GR-DOM are remarkably different. PR-DOM can be greatly influenced by human activities, and its primary element component (CHOS) contains a large number of substances that were recognized to be from the surfactant sulfonic acid. Additionally, the significant aliphatic components that emerged were from traffic pollution. In contrast, GR-DOM is less affected by human activities, and its primary element component (CHO) gives priority to natural organic matter (NOM). The most abundant substance component that occurred in GR-DOM, i.e., the highly unsaturated and phenolic compound that generally originates in the degraded humus, is initially formed by the plant residue and flushed by rainfall runoff.

[Relationship Between CO2 and CH4 Emissions in Urban Rivers and Sewage Discharging from a Municipal Drainage Network].

The increasing carbon emission of polluted rivers in urban areas is an environmental problem commonly faced by many cities in China, especially the megacities with vast populations. In this study, two typical rivers located in the megacity of Shanghai, including the suburban river network R1 and urban river R2 (in the central city), were investigated for their emission characteristics of CO2 and CH4 in dry and wet weather. We also analyzed the relationship between the state and type of river pollution and CO2 and CH4 emissions, and further explained the mechanisms of CO2 and CH4 emissions in urban rivers impacted by sewage discharged from the municipal drainage network. The results show that:① In dry weather, the average fluxes of CO2 and CH4 emitted from the river in the central city (R2) were (2.48±1.02) mmol·(m2·h)-1 and (1.21×10-2±0.71×10-2) mmol·(m2·h)-1, respectively. The average fluxes of CO2 and CH4 from the suburban river (R1) network were (1.53±0.39) mmol·(m2·h)-1 and (9.26×10-3±9.18×10-3) mmol·(m2·h)-1, respectively. In wet weather, affected by sewage from the municipal drainage network, CH4 flux emitted from the surface water of the R2 river downstream of the pump station P increased by up to 119 times that in dry weather. ② Global carbon emission statistics, involving the data from our study and from other rivers around the world, seemed to imply a relationship between the carbon emission flux and the pollution state of an urban river, i.e., the rivers with high pollution showed significant carbon emission intensity. ③ According to the results of PCA, organic matter can be an essential factor in driving the variation of carbon emissions, and this trend is evident in all the rivers in urban and suburban areas. The relationship between carbon emissions and nitrogen pollution in a river varies with different types of underlying riparian surface. In the less polluted urban rivers, the aquatic physical factor can also be an essential factor. ④ In the short term, with massive quantities of sewage discharged into urban rivers, a large amount of CH4 flux can be emitted. In contrast, in the long run, the carbon cycle can be strengthened when the carbon storage is increased, and thus the emission potential of CO2 and CH4 is improved.

The occurrence of microplastics in water bodies in urban agglomerations: Impacts of drainage system overflow in wet weather, catchment land-uses, and environmental management practices.

The footprints of microplastics in the water bodies of urban agglomerations are largely dominated by superimposed anthropogenic influences. Understanding these influences and how they are correlated is essential to better understand the occurrence and variability of microplastics in different ecosystems. This study longitudinally assessed the abundance and distribution of microplastics in the water bodies of urban agglomerations at the watershed-scale in Shanghai Megacity. Particularly, the behavior of microplastics with the impacts of drainage system overflow in wet weather (WWF), land uses, and environmental management practices were explored. WWF can greatly aggravate microplastic pollution in aquatic environments. A systemic estimation based on detailed data was used to show that the annual load of microplastics discharged via WWF in the watershed area was 8.50 × 1014 p/year, which was approximately six times larger than that discharged via the local Wastewater Treatment Plant effluent. Findings here contribute to research concerning the spatial variability of aquatic microplastics and the extent to which they are affected by land use. In descending order, the highest microplastic concentrations were found in heavy industrial > commercial/public/recreational > agricultural/light industrial > agricultural > and residential areas. The longitudinal pattern of microplastics observed in the water bodies suggested that there were superimposed effects of land use and hydrodynamics. This paper is the first to provide an integrated framework that demonstrates the significant role of environmental management practices in controlling the production and transmission of microplastics to receiving waters at a city-scale. Improved management of WWF might be a tangible solution that would help achieve an immediate and large-scale reduction of microplastics in sewage. Determining the optimized management practices for different weather or hydrological conditions could be an essential factor in decreasing microplastic concentrations and altering their flow-path pattern in a given region.

Variations in CH4 and CO2 productions and emissions driven by pollution sources in municipal sewers: An assessment of the role of dissolved organic matter components and microbiota.

Variations in methane (CH4) and carbon dioxide (CO2) emissions in municipal sewer driven by pollution sources are complex and multifaceted. It is important to investigate the role of dissolved organic matter (DOM) components and microbiota to better understand what and how those variations occurred. For this purpose, this study provides a systematic assessment based on short-term in-sewer conditioned cultivations, in conjunction with a field survey in four typical sewers in Shanghai Megacity. The results are as follows: (1) Sediment plays a main role in driving the sewer carbon emission behavior owing to its strong associations with the utilized substrates and predominant microbes that significantly promoted the gas fluxes (genera Bacteroidete_vadinHA17, Candidatus_competibacter, and Methanospirillum). (2) Aquatic DOM in overlying water is an indispensable factor in promoting total carbon emissions, yet the dominant microbes present there inversely correlated with gas fluxes (genera Methanothermobacter and Bacteroides). (3) The total fluxes of both CH4 and CO2 enhanced by pavement runoff were limited. Its high COD-CH4/CO2 conversion efficiencies can be ascribed to its dominant anthropogenic humic-like components and the emerged aquatic tyrosine-like components. (4) Domestic sewage can significantly enhance the total fluxes because of its high concentration of bioavailable DOM. However, these substrates, which were more suitable for supporting microbial growth, as well as the substrate competition caused by sulfate reduction and the nitrogen cycle (revealed by the dominant functional microbes genera Acinetobacter, Pseudomonas, Dechloromona, and Candidatus_competibacter and their correlations with indicators), seemed to be responsible for the low COD-CH4/CO2 conversion efficiencies of domestic sewage. (5) A field survey indicated the distinct features of carbon emissions of sewer sewage discharged from different catchments. An extreme hydraulic condition in a sewer in the absence of influent showed unexpectedly high levels of CO2, while a small amount of CH4 emissions.

[Removal of Microplastics by Different Treatment Processes in Shanghai Large Municipal Wastewater Treatment Plants].

Wastewater treatment plants are important sources of microplastics (MPs) in aquatic environments. The present study was conducted to investigate the number concentration, removal rate, and fate of MPs in two large municipal treatment plants in Shanghai. The MPs number concentration in the influent water of WWTP1 and WWTP2 were (226.27±83.00) piece·L-1 and (171.89±62.98) piece·L-1, respectively. WWTP1 had a MPs removal efficiency of 63.25%, which is slightly higher than that of WWTP2, at 59.84%. The removal efficiency during the primary treatment process of the two sewage treatment plants on MPs accounted for 70%-80% of the whole treatment process. The primary treatment process and secondary treatment process transferred (48.10%±1.62%) and (12.97%±0.05%) of MPs in the sewage to the sludge, respectively. As a whole, (38.82%±1.55%) of MPs in the sewage treatment plants were finally discharged into natural waters, and the remaining (61.18%±1.55%) entered the sludge. This study shows that the removal rate of MPs in Shanghai's municipal treatment plants is low and that after treatment, large amounts still enter the natural waters with the final effluent, which causes significant ecological risks. This study provides basic data of MPs removal and trends of large urban sewage treatment plants in a plain river network area, which can provide reference for further design of MPs removal processes.

Operation optimization of a photo-sequencing batch reactor for wastewater treatment: Study on influencing factors and impact on symbiotic microbial ecology.

Wastewater treatment technology with better energy efficiency and recyclability is in urgent demand. Photo-Sequencing batch reactor (SBR), which introduces microalgae into conventional SBR, is considered to have more potential for resource recycling. In this study, a photo-SBR was evaluated through the manipulation of several key operational parameters, i.e., aeration strength, light supply intensity and time per cycle, and solid retention time (SRT). The algal-bacterial symbiotic system had the potential of removing COD, NH4+-N and TN with limited aeration, representing the advantage of energy-saving by low aeration requirement. Maintaining appropriate proportion of microalgae in the symbiotic system is critical for good system performance. Introducing microalgae into conventional SBR has obvious impact on the original microbial ecology. When the concentration of microalgae is too high (>4.60 mg Chl/L), the inhibition on certain phyla of bacteria, e.g., Bacteroidetes and Actinobacteria, would become prominent and not conducive to the stable operation.