This work investigated the occurrence, spatiotemporal distribution and ecological risks of 43 emerging contaminants (ECs) in surface waters of the northwestern Taihu Basin. Twenty-six compounds were detected, comprising four endocrine-disrupting compounds, seven antibiotics, seven pharmaceuticals and personal care products, four perfluoroalkyl and polyfluoroalkyl substances and four organophosphate esters. The EC concentrations ranged from 87.4 to 602.9 ng/L, averaging 231.0 +/- 11.0 ng/L. Among these categories, ethinyl estradiol, amoxicillin, triclosan, perfluorooctanoic acid and tris-(2-chloroisopropyl) phosphate exhibited the highest concentrations. Spatiotemporal analysis revealed that the total EC concentration in the wet season (256.4 +/- 16.8 ng/L) was significantly higher than that in the dry season (205.6 +/- 13.1 ng/L, p < 0.05), primarily attributed to runoff, combined sewer overflows and sediment resuspension during heavy rainfall. Spatially, Inflows to Taihu Lake were the primary input pathways of ECs, while elevated levels of perfluoroalkyl and polyfluoroalkyl substances and organophosphate esters were observed in the Nanxi River and New Mon River Basin, indicative of industrial discharges and urban non-point sources. Ecological risk assessment revealed that most sampling sites were classified as medium-to-high risk, with high-risk sites accounting for 90.5% and 83.3% in the wet and dry season, respectively. Ethinyl estradiol was the dominant high-risk compound, contributing 84.1% and 65.7% of the total risk in the wet and dry seasons, respectively. This study highlights the diversity, seasonal variations and spatial heterogeneity of EC pollution and provides insights for water quality assessment and risk management.

Antibiotics are widely present in aquatic environments, threatening public health and ecosystem stability. This study systematically investigated the occurrence, potential sources, and ecological and human health risks of 26 antibiotics in 17 inflowing rivers of Gehu Lake. The total concentrations of antibiotics (& sum;ABs) ranged from 21.19 to 269.88 ng/L. Sulfonamides (SAs), quinolones (QNs), and tetracyclines (TCs) were the dominant antibiotic classes, with sulfamethoxazole (SMX) posing the greatest ecological risk to algal communities (risk quotient (RQ) > 1) at multiple sites. Notably, the co-occurrence of multiple antibiotics increased combined ecological risks, with algal RQ(com) > 1 at several sites. Excitation-emission matrices coupled with parallel factor analysis (EEMs-PARAFAC) identified three dissolved organic matter (DOM) components (C1-C3), among which the protein-like component C2 showed strong correlations with TCs and SAs, suggesting its indicative role in pollution source tracing and antibiotic migration dynamics. Proteobacteria dominated in high-concentration areas, with Flavobacterium and Sphingopyxis enriched as potential indicators of antibiotic contamination. Functional prediction showed that antibiotic pollution enhanced microbial pathways for drug resistance and xenobiotic degradation but weakened material cycling. stability. Human health risk assessment revealed that infants and young children were the most vulnerable population group, with elevated hazard quotient (HQ) values (>= 1) for ofloxacin (OFX), florfenicol (FLO), oxytetracycline (OTC), and chlortetracycline (CTC) at sites G3, G5, and G12. This study established a multidimensional framework to support pollution tracing, ecological risk control, and watershed management.

Stable partial nitritation is difficult to sustain in low-ammonia wastewater, as nitrite-oxidizing bacteria (NOB) outcompete ammonia-oxidizing bacteria (AOB) for limited substrate and thereby reduce nitrite accumulation. This study adopted intermittent aeration combined with hydrazine dosing and compared two sludge storage approaches to rapidly start partial nitritation at an influent ammonium nitrogen (NH4 +-N) concentration of 40 mg L-1. A single UASB reactor operated with dissolved oxygen (DO) < 0.7 mg L-1, intermittent aeration, and hydrazine addition achieved stable performance in 24 days, with 60% ammonium conversion and 77% nitrite accumulation rate (NAR). Further reducing DO to 0.6 mg L-1 cut aeration energy, stabilizing ammonium conversion at 50%, while NAR approached 100%. The measured AOB and NOB activities were 0.42 ± 0.01 and 0.1 ± 0.01 mg N (g VSS h)-1, respectively. Nitrifying sludge was preserved for 5 months at 4 °C or at ambient winter temperatures (-25 to 12 °C), then seeded into reactors R1 and R2. R1 with refrigerated sludge stabilized within 15 days, maintaining 57% ± 4% ammonium conversion and 80% NAR, with far better performance than R2. PICRUSt2 functional prediction confirmed that 4 °C sludge storage boosted AOB enrichment and upregulated ammonia monooxygenase (AMO) expression. The integrated hydrazine regulation and low-temperature sludge storage strategy enables fast, stable partial nitritation under low ammonium loading, providing technical support for mainstream PN/A applications.

Residual water from dredging contains high concentrations of heavy metals, causing severe environmental pollution in lakes. The present study develops integrated magnetic flocculation-horizontal tube sedimentation equipment. In the Wolong Lake region of China, the impact of treatment with the device on the residual water from dredged sludge under various inlet water flows was investigated. In a single-factor experiment, flocculants such as polyaluminum chloride (PAC), polymeric ferric sulfate (PFS), ferric chloride (FeCl3), and aluminum sulphate (Al2(SO4)3) were used at doses of 20-120 mg L-1 to treat the residual water from dredged sludge. The residual wastewater from dredged sludge was best treated with PAC at 60 mg L; the removal efficiency of suspended solids (SS), chemical oxygen demand (COD), total phosphorous (TP), and ammonia nitrogen (NH3-N) were (81.37 +/- 1.66)%, (44.65 +/- 2.31)%, (76.48 +/- 1.08)%, and (17.64 +/- 0.85)%, respectively. The pollutants in the water were further removed using magnetic flocculation (single-factor test and orthogonal analysis). The response surface method was used to optimize the PAC, magnetic powder, and polyacrylamide (PAM) doses to achieve 93.1% SS, 91.2% TP, and 71.2% COD removal. The device was operated for 30 consecutive days at various water intake volumes (4, 6, and 8 m3 h-1). The residual water's COD, SS, TP, and NH3-N levels effectively meet the environmental quality standards for surface water. With SpaceClaim as the pre-processing software and Fluent as the solver, a computational fluid dynamics (CFD) simulation analysis of the test device was conducted. CFD validations confirmed the design reliability. The reliability and rationality of the test device's operation were verified through simulation and analysis using the dual Euler model. The circular treatment design has significant environmental implications in restoring the ecological balance of the Wolong Lake Wetland.

Certain Fe(III) compounds are utilized to enhance anaerobic digestion performance, primarily by accelerating and stabilizing the conversion of dissolved organic matter (DOM) to methane via stimulating dissimilatory iron reduction (DIR). The effects of four specific Fe(III) compounds—Fenton sludge (FS), ferrihydrite, Fe₂O₃, and Fe(OH)₃—on DOM evolution and microbial function dynamics during anaerobic digestion were investigated in this study. Batch experiments revealed that the FS exhibited superior performance in DIR efficiency and DOM metabolism compared to other Fe(III) compounds, which is attributed to its relatively low crystallinity that enhances bioavailability and the upregulated pilA and mtrC genes expression, which further facilitated extracellular electron transfer. Combined size exclusion chromatography and fluorescence excitation emission matrix analysis demonstrated that the FS effectively degraded and transformed medium molecular weight humic-like substances. Furthermore, pathway analysis confirmed that the FS augmented acidification efficiencies, triggered by elevated activity of the propionate CoA-transferase pathway. Five genera, including Paludibacter, Macellibacteroides, Bact-08, TM7a, and Clostridium_sensu_stricto_12, were identified as keystone genera via network analysis. These genera maintained the bacterial community’s functional stability by mediating the DIR process and regulating organic matter metabolism. Overall, these findings highlight FS as a promising additive for enhancing anaerobic digestion performance, offering a sustainable strategy to optimize its practical application.

With rapid societal development, the pollution of urban rivers and lakes is becoming increasingly serious. Dredging and desilting projects are an important measure in river and lake management. Against the background of the ecological restoration of shallow lakes in northern plains, this study developed an integrated dehydration and consolidation equipment for dredged silt, targeting its application potential in cold regions. The results showed that the dehydration effect of polyacrylamide was significantly better than that of other dehydrating agents in a single dehydration experiment, and the agent did not exhibit an obvious inhibitory effect on quicklime or Portland cement. The test block consolidation strength reached 0.3 MPa, meeting the requirements for general roadbed backfill soil. The optimal ratio of dehydration and consolidation agents was 5% cement, 10% calcium oxide, 1% polyacrylamide, and 120% moisture content of the dredged silt. An integrated tubular pneumatic mixing, transmission, dehydration, and consolidation equipment was set up. The unconfined compressive strength of the test block was 0.38 MPa, and the strength ratio coefficient between the measured strength and the ratio test was 0.75. A computational fluid dynamics simulation was carried out on the test device, using the Euler-Lagrange model, and the boundary conditions were determined. The difference between the simulation and test results was less than 5%, verifying the reliability of the test device and the validity of the simulation analysis method. The structure and boundary conditions of the test device were optimized. The overall equipment is simple to operate, has low technical requirements, and is convenient and reliable.

Certain Fe(III) compounds are utilized to stimulate dissimilatory iron reduction (DIR), thereby accelerating the transformation of dissolved organic matter (DOM) during anaerobic digestion. The effects of four specific Fe(III) compounds—Fenton sludge (FS), ferrihydrite, Fe2O3, and Fe(OH)3—on DOM evolution and microbial function dynamics during anaerobic digestion were investigated in this study. Batch experiments revealed that the FS exhibited superior performance in DIR efficiency and DOM transformation compared to other Fe(III) compounds, which is attributed to its relatively low crystallinity that enhances bioavailability and the higher predicted relative abundance of pilA gene, which is consistent with enhanced extracellular electron transfer. Combined size exclusion chromatography and fluorescence excitation emission matrix analysis demonstrated that the FS effectively degraded and transformed medium molecular weight humic-like substances. Furthermore, pathway analysis confirmed that the FS augmented acidification efficiencies, triggered by elevated activity of the propionate CoA-transferase pathway. Five genera, including Paludibacter, Macellibacteroides, Bact-08, TM7a, and Clostridium sensu stricto 12, were identified as keystone genera via network analysis. These genera maintained the bacterial community’s functional stability through their potential involvement in the DIR process and regulation of organic matter metabolism. Overall, these findings highlight FS as a promising Fe(III) source that drives efficient DIR-coupled DOM transformation, suggesting its potential for the resource recovery of Fenton sludge.

Reverse osmosis membrane filtration concentrate is a type of organic wastewater from landfill leachate treatment that has a high concentration of organic matter, refractory macromolecules, and low biodegradability. The reverse osmosis concentrate was treated in this study using a combination of physicochemical and biological processes. Single-factor test analysis for coagulation and sedimentation indicated that 2000 mg L-1 of polymeric ferric sulphate (PFS), a pH of 7, and a precipitation time of 40 min yielded the best removal effect. The COD, NH3-N, and UV254 removal efficiencies were 74%, 34%, and 64%, respectively. The influent of the electrochemical oxidation is the effluent pretreated by coagulation and precipitation. The anode material was a ruthenium-iridium-titanium plate electrode, and the cathode material was a stainless-steel plate electrode. The removal efficiencies of COD, NH3-N, and UV254 in the electrochemical oxidation process were 67%, 83%, and 80%, respectively. The BOD5/COD ratio increased to 0.5, and the unit energy consumption of COD was 39.4038 kW h kg-1. The electrochemical oxidation effluent was then subjected to advanced treatment in an aerated biological filter. The influent flow rate was 0.3 L h-1, the air-to-water ratio was 4 : 1, and the temperature was 20 degrees C-30 degrees C. No glucose was added to the subsequent influent. The COD, NH3-N, and UV254 removal efficiencies were 71%, 73%, and 69%, respectively. Following biological treatment in the aerated biological filter, the B/C ratio of the reverse osmosis membrane concentrate improved. The operational results of the combined processes indicated removal efficiencies of 97%, 98%, and 97% for COD, UV254, and NH3-N, respectively. The effluent quality attained the Class A standard of the Pollutant Discharge Standard for Urban Sewage Treatment Plants (GB18918-2002).

Sulfur-driven autotrophic denitrification (SAD) coupled with anaerobic ammonium oxidation (Anammox) offers a low-carbon route for nitrogen removal. In this study, a one-stage integrated Anammox-SAD bioreactor was developed to treat partially nitrified high-strength nitrogenous wastewater under autotrophic conditions. At influent ammonium and nitrite concentrations of 300 f 20 and 350 f 40 mg/L, the system achieved stable nitrogen conversion at a hydraulic retention time of 0.57 d, maintaining effluent total nitrogen below 40 mg/L and an overall nitrogen removal efficiency of approximately 90%. Microbial community analyses demonstrated rapid functional specialization within the bioreactor, with sulfur-oxidizing denitrifiers (e.g., Thiobacillus and Ignavibacterium) dominating the SAD zone, while the Anammox compartment was enriched in Candidatus Kuenenia. Metagenomic profiling revealed functional maturation of the coupled system, characterized by reinforced terminal denitrification genes (norC and nosZ) and sulfur oxidation pathways (sqr, soxB, and ETHE1/sdo) in the SAD zone, together with recovery of core Anammox genes (hzsABC and hdh) after transient disturbance. The integrated configuration stabilized nitrite fluxes, alleviated inter-process competition, and promoted synergistic nitrogen conversion within a compact one-stage system. These findings provide mechanistic guidance for designing energy-efficient SAD-Anammox systems for advanced wastewater treatment of nitrogen-rich wastewater.

Salinity-alkalinity gradients impose strong environmental filtering on soil microbial communities, yet the respective roles of generalist and specialist taxa in community assembly and stability remain insufficiently understood in wetland ecosystems. Here, bacterial and fungal communities were investigated across low, moderate, and high saline-alkaline zones in the Luyang Lake wetland, China. Amplicon sequencing was integrated with niche breadth analysis, community assembly inference, co-occurrence network analysis, cohesion metrics, and partial least squares path modeling to assess how generalists and specialists responded to environmental variation and contributed to microbial stability. Bacteria contained a larger generalist pool, whereas fungi were relatively enriched in specialists. Generalists were positively associated with nutrient availability and negatively associated with saline-alkaline stress, while bacterial specialists showed the opposite trend. Niche breadth decreased with increasing salinity-alkalinity, especially in bacteria, and this narrowing was accompanied by stronger deterministic assembly, mainly homogeneous selection. Network analysis further suggested that generalists contributed more to overall community connectivity, whereas specialists became more important for network organization under stronger saline-alkaline stress. Path modeling indicated that bacterial and fungal community stability was associated with distinct response pathways. Overall, salinity-alkalinity reorganized microbial communities by reducing niche breadth, strengthening deterministic assembly, and shifting the relative contributions of generalists and specialists to community stability. These findings improve our understanding of how niche strategy mediates microbial assembly and stability in saline-alkaline wetland soils.

This study innovatively introduced birnessite-coated sand as a substrate for constructed wetlands to systematically explore its denitrification efficiency and mechanism in the effluent from urban sewage treatment plants, addressing drawbacks of conventional substrates, such as a single denitrification pathway and low-load shock resistance. By constructing an experimental wetland system, "gravel+birnessite-coated sand+sand" (CW-Mn), and a control wetland system, "gravel+quartz sand+sand" (CW-C), and by combining dynamic hydraulic load regulation and microbial community analysis, the denitrification advantages and synergistic pathways of manganese-based wetlands were revealed. Under stable operating conditions: HRT72 h, HLR 0.34 m3/(m2·d), removal efficiencies of NH4+-N and TN in CW-Mn reached 67.56% and 62.85%. Birnessite-coated sand is proposed to form characteristic nitrogen transformation zones via pathways including Mn-reduction-mediated NH4+-N oxidation, Mn oxidation coupled with nitrate reduction, and conventional nitrification with limited denitrification. Efficient NH4+-N removal was achieved in the root zone of plants, confirming the synergistic denitrification mechanism of the oxidation-transition-reduction layer. SEM-EDS revealed that the surface formation consisted of spiky manganese oxides or hydroxides. XPS analysis confirmed that the average oxidation state of manganese decreased from 3.37 to 2.49, a significant positive correlation between manganese reduction and NH4+-N conversion. Under influent pollutant concentrations, removal efficiencies of NH4+-N and TN in CW-Mn reached 90% and 29.94%, respectively. Actinobacteria formed a synergistic denitrification process through biofilm formation in root layer, whereas Proteobacteria dominated denitrification and manganese oxidation in the CW-Mn substrate layer. Nitrate reduction was optimized by the increased abundance of denitrification genes. This study provides a theoretical basis for the engineering application of urban wastewater treatment by demonstrating that high-valence manganese oxide composite substrates can enhance nitrogen transformation and improve total nitrogen removal under optimized operating conditions.

This study uses domestic sewage to dilute landfill leachate, conserve freshwater resources, and supplement phosphorus. The proportion of landfill leachate is increased, and the microalgae photosynthesis is coupled with the SBR system to process the diluted leachate. A bacterial and algal symbiotic photobioreactor (PBR) was constructed to improve the efficiency of sewage treatment by optimizing parameters (aeration rate, light) for investigating the synergy of microalgae and bacteria, and the effect of treating Landfill leachate. The long-term operational impact of the reactor under two different inoculation conditions was investigated: one group was inoculated only with activated sludge and controlled light to promote the spontaneous growth of microalgae (Rc), and the other group was inoculated with activated sludge and Chlorella (Rs). The highest pollutant removal efficiencies were observed in 4 : 1 (microalgae/sludge) cultures, with COD at 96.5%, NH4 +-N at 97.4%, and PO4 3--P at 92.3%. Synergistic growth of bacteria and microalgae was observed, with a total biomass concentration of 2.32 g L-1. Pollutant removal effect was best at an aeration rate of 0.6 L min-1, with removal efficiencies of 72.7% for COD, 78.3% for NH4 +-N, and 62.5% for PO4 3--P. A low-aeration method, mechanical aeration and microalgae photosynthesis cooperated to reduce operating costs. When light intensity was 108 µmol m-2 s-1, pollutant removal efficiencies of COD 82.6%, NH4 +-N 84.9% and PO4 3--P 75.9% were achieved. Treatment effect of the Rs system: average volume load of 36.22 mg per L per h COD, 8.53 mg per L per h NH4 +-N, 0.44 mg per L per h PO4 3--P. This provides new ideas for achieving high-efficiency, low-consumption green biological treatment of landfill leachate.

The treatment of landfill leachates is considered to be one of the most difficult processes among organic wastewater treatments. This study aims to address the challenge of treating landfill leachates by developing a new combined Fenton/biological activated carbon filter process to efficiently treat organic matter, ammonia nitrogen (NH4+-N), and chromaticity. Under optimal Fenton process conditions (pH 4, H2O2 dosage of 15 mL L-1, n(H2O2) : n(Fe2+) = 4 : 1, and reaction time of 100 min), the removal efficiencies of COD, chromaticity, and NH4+-N reached 75.05%, 98.32%, and 30%, respectively. Response surface methodology confirmed that the significance of influencing factors follow the order of pH > H2O2 dosage > n(H2O2) : n(Fe2+) > reaction time, with a verified COD removal efficiency of 74.36% (minimal error). For the SPC/Fe2+ process, optimal conditions yielded COD, chromaticity, and NH4+-N removal efficiencies of 58.39%, 84.21%, and 20.30%, respectively. The BAC filter achieved effective COD removal (27.3%) and excellent NH4+-N removal (61.90%). The Fenton/BAC combined process achieved a remarkable treatment performance for landfill leachate, with a COD removal efficiency of 81.86%, NH4+-N removal efficiency of 73.33%, and chromaticity removal efficiency of 98.50%. Notably, the biodegradability index (B/C) of the landfill leachate increased from 0.31 to 0.51, confirming the synergistic mechanism of organic matter and NH4+-N removal by BAC. This study innovatively constructs a Fenton/BAC combined process, quantifies the synergistic removal effects of adsorption-biofilm-microbial degradation by BAC on leachate organics and NH4+-N, and clarifies the SPC/Fe2+-Fenton performance-cost trade-off, providing a new technical route for efficient leachate treatment. This novel combined process offers promising research directions and significant theoretical and practical value for efficient leachate treatment.

Ozonation is a commonly used method to enhance coagulation during reclaimed water treatment, which can significantly reduce the formation of disinfection byproducts (DBPs) due to the removal of dissolved organic matter. However, effects of different combination sequences and operation conditions of ozonation-enhanced coagulation on effluent organic matter (EfOM), especially dissolved organic nitrogen (DON), as well as the subsequent DBP formation and toxicity are not well investigated. In this study, the coagulation effects of polyaluminum chloride (PAC) and polyferric sulfate (PFS), as well as the optimal coagulation conditions were determined. The effects of the ozone dose and combination sequence of ozonation-enhanced coagulation on EfOM properties, DBPs, and acute toxicity were investigated. The results showed that the optimal coagulation conditions were achieved by PFS at a dose of 80 mg/L, and removal efficiencies of dissolved organic carbon (DOC), DON, and acute toxicity were 36%, 40%, and 21%, respectively. For ozonation-enhanced coagulation, the optimal removal efficiencies were achieved at a 1 mg/L ozone dose. Among the three combination sequences, the hybrid ozonation-coagulation process had the highest removal efficiencies for DON (43.8%), carbonaceous DBPs (34.5%), nitrogenous DBPs (33.8%), and total organic halogen (38.0%), respectively. For DOC and acute toxicity, the highest removal efficiencies were achieved by the post-ozonation process (20.9%) and pre-ozonation process (16.4%), respectively. The formation of center dot OH and the increasing Fec content led to the enhancement of the hybrid ozonation-coagulation process, and the decreasing Feb content led to the negative impact on the removal of DOC by the hybrid ozonation-coagulation process.

Conventional heterotrophic denitrification (HD) struggles with efficient nitrogen removal from low carbon-to-nitrogen (C/N) ratio wastewater due to reliance on external carbon sources and high costs. The sulfur-iron autotrophic denitrification (SIAD) technology integrates the advantages of sulfur autotrophic denitrification (SAD) and nitrate-dependent ferrous oxidation (NDFO) through synergistic interactions between sulfur and iron, achieving high-efficiency nitrogen and phosphorus removal, pH self-regulation, and sulfate (SO42-) control. This article provides a comprehensive review of the theoretical mechanisms, efficiency optimization, and engineering applications of SIAD technology, aiming to elucidate the efficient nitrogen removal pathways driven by synergistic multi-electron donors. Additionally, the article explores the coupling of SIAD with other biological denitrification processes, such as HD and anaerobic ammonium oxidation (Anammox), demonstrating its potential and advantages in practical implementations. It also analyzes current challenges of SIAD and summarizes future trends, aiming to provide guidelines for advancing this low-carbon, high-efficiency technology in low C/N wastewater treatment.

Enhancing substrate transfer is crucial for promoting the nitrogen removal rate of Anammox granular sludge, as the shape of the granules significantly influences substrate diffusion. In this study, inspired by biomimicry principles, we propose a novel red blood cell-like granular sludge to increase the contact area and improve substrate transfer. The startup and operation of Anammox granular sludge in low-strength ammonia nitrogen wastewater were successfully achieved through an increase in substrate volume flux (SVF). As the SVF increased from 2.38 to 7.43 L2/(g VSS center dot h), specific Anammox activity (SAA) rose from 0.138 to 0.483 g N/(g VSS center dot d). The Anammox granular sludge system achieved a total nitrogen removal efficiency of 85.70 % and a nitrogen removal rate (NRR) of 0.792 kg N/(m3 center dot d) after 126 days. Notably, red blood cell-like granular sludge was observed by day 116. The rise in SVF induced a granule structure more conducive to substrate transport, improving the granules' efficiency in substrate uptake and thereby enhancing their SAA. High-throughput pyrosequencing revealed that the dominant bacteria using the SVF-enhancing strategy remained anaerobic ammonium oxidizing bacteria (AnAOB) (29.53 %-29.89 %), with an increased diversity of species, including Candidatus Kuenenia, Candidatus Anammoxoglobus, and Candidatus Brocadia.

Emerging contaminants (ECs) have drawn significant attention due to their adverse effects on aquatic ecosystems. This study investigated the spatiotemporal distribution and ecological risks of 43 ECs in surface water and examined their fate in wastewater treatment plants (WWTPs) in the lower Yangtze River basin. In surface water, 34 ECs were detected, including 13 antibiotics, 4 endocrine-disrupting compounds, 9 pharmaceutical and personal care products, 4 perfluoroalkyl and polyfluoroalkyl substances and 4 organophosphate esters. Specifically, doxycycline, ethinyl estradiol, salicylic acid, perfluorooctanoic acid and triisobutyl phosphate showed dramatic spatiotemporal variations. Temporally, doxycycline, salicylic acid, ibuprofen, diclofenac and perfluorooctanoic acid peaked in winter, whereas ethinyl estradiol and triisobutyl phosphate showed higher concentrations in summer and autumn. Spatially, bisphenol A and octyl phenol were more concentrated in the downstream section, while triisobutyl phosphate levels were higher in the upstream section. Risk assessment indicated 82 out of 87 water samples posed medium or high ecological risk, and sulfamethoxazole, roxithromycin, ethinyl estradiol and octyl phenol were identified as primary contributors. Although the removal efficiencies of ECs in industrial and municipal WWTPs were 87.1 ± 1.5 % and 83.6 ± 1.5 %, respectively, EC concentrations in effluents were 2.70 and 6.15 times higher than those in surface water. Correlation analysis further confirmed that the discharges from WWTPs were highly related to the existence of these ECs in the lower Yangtze River. The effluent concentrations of perfluorooctanoic acid, doxycycline, Triethyl phosphate, roxithromycin and Tris-(2-chloroisopropyl) phosphate usually exceeded 20 ng/L due to their low removal efficiencies, where moreover, ECs with high influent concentrations but removal efficiencies above 80 % still posed significant effluent risks. These results suggest that, besides adopting advanced treatment technologies (e.g., adsorption, ion exchange), source control is also crucial. This study offers key insights into Yangtze River EC pollution, supporting better monitoring and management.

Sediment restoration has become a key link in river and lake pollution control. This present study investigated the selection of dominant microbial bacteria, the selection and optimization of microbial immobilized carrier materials, and the effect of embedded immobilized microbial in situ remediation of bottom sediments based on the actual restoration pilot project of eutrophic Wolong Lake. The composite of denitrifying and photosynthetic bacteria at a ratio of 1 : 2 showed the best performance with COD, TN, and TP removal efficiencies of 74.86%, 65.2%, and 67.5%, respectively. Denitrifying bacteria to photosynthetic bacteria optimal composite bacterial solutions with polyvinyl alcohol-sodium alginate (PVA-SA), PVA-SA-zeolite and PVA-SA-biochar carriers were selected, and the effects of different carriers were analyzed and compared in terms of multiple characteristics. PVA-SA-biochar carriers showed the best ammonia-nitrogen transfer performance, mass transfer coefficient (0.681 x 10-9 m2 s-1), specific surface area (76.3 m2 MB g-1) and performed best in mechanical strength and chemical stability. The effects of biochar, PVA and SA contents on COD removal (Y) were analyzed using the 3D-response surface methodology. Biodegradation capacity (G-value) increased from 0.68 x 10-3 kg (kg h)-1 at the beginning of the test to 2.32 x 10-3 kg (kg h)-1 after 80 days of the remediation test with a growth rate of 258.82%. The water quality index has significantly improved, indicating a good restoration effect. Alpha diversity analysis showed that the Shannon and Simpson indexes increased and decreased. The relative abundance of Bacteroidota, Proteobacteria, Planctomycetota and Chloroflexi, closely related to the denitrification, decarbonization and phosphorus removal, increased while Chloroflexi decreased compared with before restoration. Embedded immobilized microbial technology significantly enhances the quality of sediment mud and the overlying water. In the long term, this approach does not release toxic substances into water bodies, thus fostering biodiversity and promoting ecological restoration. It represents a novel restoration strategy that contributes positively to environmental sustainability.

To date, there remains a lack of comprehensive understanding regarding the impacts of water diversion project on large-scale receiving watersheds. Large-scale water diversions not only introduce external phosphorus but also alter hydrological conditions, leading to the redistribution of phosphorus within the watershed. In this study, the distribution of phosphorus species in sediments and waters was examined in detail through a case study of a water diversion project in the Taihu Lake Basin, China. The concentration of total phosphorus (TP) increased in both surface waters and sediments following the commencement of the project, particularly in surface waters, where it was 1.27 times higher. In terms of spatial distribution, the concentrations of TP in both waters and sediments exhibited a pattern of initial decrease followed by an increase along with the direction of water flow. The highest average TP levels were observed in area A (311.56 μg/L in water and 670.98 mg/kg in sediment, respectively), where water was diverted, due to the introduction of a significant amount of particulate phosphorus (PTP). As the deposition of PTP occurred, the TP concentrations in area B dropping to 222.64 μg/L in water and 523.42 mg/kg in sediment. However, there was an slight increase in colloidal phosphorus (CTP) and dissolved phosphorus (DTP) in area B. Turbidity and conductivity measurements suggested that water transfer may have facilitated the conversion of PTP or slightly disturbed the sediment, leading to the production of CTP and DTP. In area C, where rivers converged, the TP concentrations in water and sediment increased to 313.83 μg/L and 551 mg/kg, respectively. The increased turbidity indicated that the convergence of rivers had a significant impact on the release and redeposition of PTP between sediments and overlying water. This study provided new sights for the dynamic changes of phosphorus species with large-scale water diversion projects.

Anaerobic ammonium oxidation requires the influent NO2--N/NH4+-N ratio to be 1.32 : 1. At low temperatures, poor sludge settling performance, expansion, and loss are profound. The effluent water quality cannot meet the influent requirements of the anaerobic ammonium oxidation stage. In this study that was operated for more than 300 days, the SBR was used to inoculate flocculent sludge and cultivate it to form aerobic granular sludge (AGS), which was then domesticated into partially nitrosated granular sludge (PNGS), and gradually reduced to low-temperature for intensive cultivation. During the cooling process, the ratio of NO2--N/NH4+-N in the effluent was maintained by controlling the aeration time and the operating cycle of the SBR to achieve the best partial nitrosation efficiency. PNGS cultured increased the volumetric load of NH4+-N removal from 0.24 kg (m-3 d-1) to 0.35 kg (m-3 d-1) at 15 degrees C compared with 30 degrees C. Fly ash was used as the crystal nucleus and carrier to prevent the disintegration of AGS at low temperatures (15 degrees C). The effect of fly ash dosages 50, 100, 150, 200, 250, 300 mg L-1 on partial nitrification efficiency was determined. It accelerates the formation of new AGS and improves partial nitrification performance. Compared with no fly ash addition at 15 degrees C, when fly ash dosage of 250 mg L-1 was added, the NO2--N accumulation rate increased from 75% to 85%, and NH4+-N volume removal load increased from 0.35 kg (m-3 d-1) to 0.45 kg (m-3 d-1). Effluent NO2--N/NH4+-N increased from 0.55 : 1 to 1.20 : 1. Effluent NO2--N/NH4+-N meets anammox influent requirements. This study can be used to build sustainable wastewater treatment in low-temperature regions worldwide.