To achieve stable and efficient sludge reduction, this study employed an oxidant-microbial combined process. Sludge was pretreated with Oxone, followed by inoculation of strain YH14 (lysozyme-producing) and newly isolated strain XSC8 (biosurfactant-producing) for reduction treatment. The optimal sludge reduction efficiency was achieved when Oxone and FeSO4 dosages were 0.70 and 0.35 mmol/g SS, with inoculation amounts of strains YH14 and XSC8 at 3 and 6% (v/v). Compared with untreated original sludge, significant improvements were observed: there was a 25.9% increase in suspended solids (SS) reduction efficiency, while that of volatile suspended solids (VSS) rose by 23.7%, while the concentration of soluble chemical oxygen demand (SCOD) rose by 2135.06 mg/L. Additionally, variations in the sludge other physicochemical properties were indicative of both extracellular polymeric substances (EPS) disassembly and cellular disruption. High-throughput sequencing analysis revealed enhanced capacities of membrane transport and lipid metabolism in the sludge.

The completely autotrophic nitrogen removal over nitrite (CANON) process represents an energy-efficient strategy for wastewater treatment, but its practical application is constrained by slow and unstable startup owing to aeration. While previous studies have primarily focused on iron-mediated enhancement in standalone anammox systems without aeration, this work demonstrates that exogenous Fe(III) enhances CANON system startup through an integrated iron-nitrogen coupling mechanism under aerated conditions. Through 140-day continuous experiments with gradient Fe(III) concentrations, 5 mg/L Fe(III) was identified as optimal, achieving rapid startup within 88 days and superior nitrogen removal efficiency (81.6%). Higher dosage (10 mg/ L) induced performance inhibition due to excessive nitrate accumulation. Fe(III) established a continuous biogeochemical cycle where the Fe(III)/Fe(II) cycle served as a microbial-chemical bridge, effectively coupling anammox with partial nitrification, DNRA, and ANRA. Microbial community analysis confirmed specific enrichment of Candidatus_Brocadia under optimal Fe(III) supplementation. Metagenomic evidence indicated that Fe(III) increased key functional genes to enhance essential metabolic pathways including iron uptake, transport and iron-sulfur (Fe-S) cluster assembly. This study provides the evidence of iron-nitrogen coupled mechanism under aeration in CANON system, establishing a complete chain from iron transformation to microbial synergy. These findings offer valuable insights for optimizing iron-enhanced anammox processes in wastewater treatment.

A microencapsulated intumescent flame retardant (MIFR) powder was fabricated via in-situ polymerization, consisting of a melamine polyphosphate and silicone oil composite core enclosed within a cross-linked hexamethoxymethylmelamine (HMMM) shell. Unlike conventional intumescent flame retardants that suffer from poor compatibility and premature decomposition in bitumen, the core-shell architecture of MIFR provides controlled release of active components precisely at the onset of thermal degradation. Morphological characterization confirmed spherical microcapsules with intact core-shell microstructure. Shell thickness ranged from 1.1 μm to 3.4 μm depending on the core/shell ratios, with 1/1 (MIFR-1/1) giving 1.8 μm. Nanoindentation tests showed a hardness of 0.38 GPa, and thermogravimetric analysis (TGA) revealed an initial decomposition temperature of 352 °C, ensuring stability during bitumen mixing at 165 °C. When incorporated into bitumen binder at 10 wt%, MIFR-1/1 reduced peak heat release rate by 22.6%, total heat release by 47.5%, and total smoke production by 50.0% in cone calorimeter tests. The significant smoke reduction is attributed to the synergistic action of the intumescent char layer in the condensed phase and the dilution effect of inert gases released from MPP decomposition in the gas phase. Scanning electron microscopy (SEM) of residual chars revealed a highly expanded intumescent char with closed cell structure, establishing a dual phase flame retardant mechanism. Conventional physical property testing of 8 wt% MIFR modified bitumen gave a penetration of 55 dmm, a softening point of 55.7 °C, and a ductility of 101 cm at 5 °C, representing a balanced compromise between thermal stability and low temperature deformability. The core-shell architecture enabled controlled flame-retardant release, demonstrating that MIFR powder is an effective additive for improving fire safety of bituminous binders in tunnel and bridge pavements, where fire hazards pose serious risks to both infrastructure integrity and public safety.

Surface water is increasingly plagued by a growing menace of nitrate (NO3- -N) and heavy metal contamination, which poses a threat to water quality and safety. To tackle the problem, this research constructed three biofilm reactors designed to simultaneously remove NO3 --N, Cu(II), and Zn(II). These reactors utilized Mn3O4-modified activated carbon (AC) and polyurethane (PU) sponge that underwent composite doping, along with the loading of Zoogloea sp. MFQ7. Following a comprehensive 150-day operation, the reactor demonstrated consistent NO3 - -N removal efficiency (NRE) of 88.67%, successfully overcoming the limitation of insufficient electron donor at a low C/N ratio of 1.5 (HRT=6 h, pH=7.0). Upon the introduction of Cu(II) and Zn(II) at 0.5 mg L- 1 each, the system exhibited removal efficiencies of 80.81% for Cu(II) and 77.20% for Zn(II). According to experimental findings, the Mn3O4@AC carrier provided manganese source via the slow release of Mn(II) and accelerated electron transfer simultaneously, which constituted the core innovation for achieving efficient denitrification under low C/N ratio conditions. Adsorption by the bio-precipitate was the main approach to the removal of Cu (II) and Zn(II). Although the microbial community composition shifted under Cu(II) and Zn(II) stress, the system maintained functional stability. The research offers an innovative viewpoint on addressing contamination in micro-polluted surface water, highlighting the application potential of Mn-modified carriers in carbon-limited environments.

Agricultural wastewater typically contains nitrate (NO3--N) and atrazine (ATZ), while autotrophic denitrification driven by pyrite is hindered by surface passivation. This study reported the isolation of Aromatoleum evansii LY15 and demonstrated a self-sustaining iron-sulfur (Fe-S) redox cycle that alleviated passivation and maintained electron flux for robust NO3--N removal. Batch assays using soluble Fe2+/Fe3+, thiosulfate, sulfate, and natural pyrite revealed that the combination of Fe2+ and thiosulfate achieved the highest NO3--N removal efficiency (80.86 %) among all tested soluble electron donors. Pyrite (4 g L-1, 80 mesh) facilitated near-complete NO3--N removal (99.95 %) within 144 h and effectively promoted the removal of total phosphorus from real wastewater samples under neutral pH. Dialysis experiments found that direct cell-mineral contact was essential for efficient electron exchange. Electrochemical analyses revealed a sharp decrease in charge-transfer resistance and intensified Fe-S redox currents, confirming microbially mediated pyrite activation. The presence of secondary Fe-S phases (e.g., Fe3O4, FeS, Fe3S4) and intermediate sulfur species (S0/Sn2-) signals verified dynamic Fe-S cycling. ATZ exhibited concentration-dependent effects, with concentrations of 0.5-1.0 μM stimulating denitrification, extracellular electron transfer, and Fe-S cycle. Electron paramagnetic resonance and mass spectrometry analyses revealed free radical pathways (SO3·-, ·OH) and biological transformations as the primary mechanisms accounting for more than 95 % ATZ removal at low concentrations. Overall, strain LY15 orchestrated a bidirectional Fe-S cycle that alleviated pyrite passivation, coupling NO3--N removal with ATZ attenuation, establishing a practical paradigm for resilient mineral-based treatment of complex agricultural wastewater.

This study systematically investigates the interfacial evolution and long-term oxidative aging behavior of waste polyethylene (WPE) modified bitumen compatibilized with ethylene-vinyl acetate (EVA). The severe thermodynamic immiscibility between WPE and bitumen typically leads to phase separation and performance deterioration. This research demonstrates that EVA acts as a highly effective macromolecular compatibilizer, forming a coherent interphase that stabilizes the composite's microstructure. The aging process was deconstructed through a multi-scale approach combining advanced microscopy (Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM)), Fourier-transform infrared (FT-IR) spectroscopy, thermal analysis (Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC)), and rheomechanical characterization. The results reveal that EVA compatibilization dramatically reduces the high-temperature storage softening point difference (Delta T) from 5.7 degrees C to 1.2 degrees C, indicating suppressed macroscopic phase separation. Under prolonged pressurized oxidative aging (60 h, Pressure Aging Vessel (PAV)), the compatibilized system exhibits a markedly moderated and homogeneous aging response. Its complex modulus (G*) increased by only 83% compared to a 900% increase for the uncompatibilized blend, while retaining a substantially higher phase angle delta (34.5 degrees vs. 12 degrees). Consequently, the EVA-compatibilized binder showed superior durability, retaining 64% of its initial fatigue life and maintaining acceptable low-temperature flexibility (m-value=0.278) after aging, in stark contrast to the catastrophic embrittlement of the uncompatibilized counterpart. This work establishes that the strategic engineering of the polymer-bitumen interface via compatibilization transforms the aging trajectory from a rapid, heterogeneous failure to a controlled, homogeneous degradation process, providing a crucial pathway for developing durable and sustainable pavement materials from post-consumer plastic waste.

Deep treatment of photovoltaic wastewater is one of the core environmental challenges constraining its green development. This study isolated a salt-tolerant strain, Acinetobacter LX-6, exhibiting both efficient heterotrophic nitrification-aerobic denitrification and biomineralization capabilities. Under optimal cultivation conditions, removal efficiencies for fluoride (F-), ammonia nitrogen (NH4+-N), calcium (Ca2+), and orthophosphate phosphorus (PO43--P) reached 81.00%, 99.33%, 87.78%, and 87.63%, respectively. Increased secretion of loosely associated extracellular polymers (LB-EPS) may enhance the resistance of strain LX-6 to F- stress and promote the biomineralization process. Under exposure to low-dose stressor F- (5-25 mg L-1), strain LX-6 exhibited positive biological effects, thereby promoting its growth and reproduction. Increased electron transfer activity and enhanced antioxidant enzyme activity helped strain LX-6 maintain high metabolic activity. Under exposure to F- at 30 mg L-1, the bacterial antioxidant defense system fails to counteract the oxidative stress induced by high F- concentrations. This leads to a sharp increase in cell membrane permeability, impairs microbial metabolic functions, and significantly inhibits pollutant removal efficiency. Strain LX-6 achieves efficient F- removal through extracellular adsorption, ion exchange, and coprecipitation. These findings provide important insights for optimizing biological wastewater treatment systems to achieve deep fluoride removal.

Deteriorating environmental quality, significantly driven by the release of untreated industrial effluent, jeopardizes water ecosystems and threatens human health. Conventional treatment methods often struggle to efficiently remove such complex effluents. This paper proposed a novel fungal-bacterial-algal (FBA) symbiotic system capable of simultaneously and efficiently removing nitrate (NO3--N), Zn2+, and Cu2+ from industrial wastewater. By optimizing the carbon-to-nitrogen ratio, pH, and hydraulic retention time, the system demonstrated outstanding removal performance even under heavy metal stress conditions. Product metabolism analysis indicates synergistic enhancement of microbial activity within the fungal-algal symbiosis. Precipitation characterisation demonstrated that FBA achieves heavy metal immobilization and removal through biomineralization and adsorption mechanisms. Microbial community and gene prediction analyses revealed interspecies functional synergistic mechanisms. This study provides an efficient and sustainable solution for treating complexly polluted industrial wastewater.

The coexistence of nitrate, heavy metals, and emerging organic contaminants in wastewater poses significant challenges to conventional biological treatment, particularly under carbon-limited conditions. This study isolated and identified a strain with high efficiency in both manganese (Mn) oxidation and denitrification, designated ZY8, and systematically evaluated its potential for simultaneous removal of multiple pollutants. Under optimal conditions (C/N = 2.0, pH = 6.5, Mn (II) = 20.0 mg L-1), strain ZY8 achieved 98.5% nitrate removal and 90.0% Mn (II) removal within 16 h. Mechanistic investigations revealed that Mn oxidation served as an alternative electron donor to drive denitrification, with comprehensive elucidation of electron transfer pathways and Mn transformation dynamics. Furthermore, strain ZY8 exhibited significant removal capacity toward combined ibuprofen (IBU) and cadmium (Cd (II)) contamination (86.9% and 84.6%, respectively), primarily attributed to the adsorption effects of extracellular polymeric substances (EPS) and biogenic manganese oxides. Critically, the biogenic manganese oxides generated during Mn oxidation served as multifunctional mediators facilitating electron transfer, adsorbing pollutants via surface complexation, and alleviating oxidative stress through ROS scavenging - thereby playing a central role in the coupled removal process. This study elucidates the mechanism of Mn oxidation-denitrification coupling and pollutant removal mediated by the ZY8 strain, and reveals its stress response characteristics under complex pollution conditions. These findings provide both a promising microbial resource and theoretical foundation for developing innovative bioremediation strategies targeting multi-pollutant wastewater treatment, offering practical implications for environmental management of industrial effluents containing coexisting heavy metals and organic contaminants.

This study introduces a paradigm shift in asphalt technology by developing a sustainable bitumen material with autonomous self-nourishing and self-healing capabilities. The innovation centers on pH-responsive microcapsules, engineered with a chitosan/sodium alginate (CS/SA) shell to encapsulate waste soybean cooking oil (WSCO). Unlike conventional passive shells, this intelligent design leverages the local acidification from bitumen oxidative aging as an intrinsic trigger. The microcapsules, fabricated via coaxial electrospray (20-50 mu m, 91.5 % encapsulation efficiency), demonstrated excellent thermal stability (up to 250 degrees C) and mechanical robustness. They exhibited a remarkable pH-triggered release: cumulative WSCO release reached 78.3 % at pH 4.0 over 96 h, compared to only 12.5 % at pH 7.0. In bitumen, this dual functionality was conclusively validated. The selfnourishing action significantly mitigated aging, with 5.0 wt% microcapsules reducing the complex modulus increase after aging to just 43 % versus 1142 % for neat bitumen. Simultaneously, the self-healing efficiency reached 68.4 % with 4.0 wt% microcapsules, maintaining 58.9 % after five healing cycles. This synergistic proactive and reactive system, which effectively upcycles waste oil, offers a transformative solution for drastically prolonging pavement service life and enhancing the sustainability of infrastructure materials.

Currently, the biological treatment of combined-pollutant chemical wastewater has become a research hotspot and challenge. In this study, tourmaline (Tm)- and coconut shell biochar (CB)-modified polyurethane sponges (TCBPs) loaded with Stutzerimonas sp. YX13 were prepared to construct an immobilized bioreactor. Under optimal operating conditions, the removal efficiencies of nitrate (NO3--N), phosphate (PO43--P), calcium (Ca2+), nickel (Ni2+), and ibuprofen (IBU) in this reactor reached 91%, 89%, 78%, 97%, and 96%, respectively. The research suggested that TCBPs materials enhanced electron transfer rates within the system, thereby increasing bacterial metabolic activity and nitrogen removal performance. In addition, Tm stimulated microorganisms to secrete more extracellular polymeric substances (EPS) to promote pollutant removal. The characterization results indicated that PO43--P, Ca2+, Ni2+ and IBU were primarily removed through coprecipitation and adsorption. Community structure analysis indicated that Pseudomonas was the dominant bacterium throughout all stages of the reactor. KEGG results demonstrated that pollutant addition inhibited the expression of denitrification-related genes. This study provides a novel reference for treating combined pollutants from chemical wastewater through microbial-induced calcium precipitation.

To mitigate nitrate-herbicide co-contamination in agricultural runoff while valorizing discarded aquatic biomass, we developed a waste-derived biogenic iron sulfide (bio-FeS) synthesized via sulfate-reducing biomineralization on discarded aquatic plants (DAP). Bio-FeS was coupled with an Fe-S cycling denitrifying bacterium (Aromatoleum evansii LY15) to enhance simultaneous nitrate (NO3--N) removal and atrazine (ATZ) transformation under anoxic conditions. The strain LY15@bio-FeS system achieved 98.9% NO3--N removal and over 85% ATZ degradation (0-1.0 mu M) within 72 h, and maintained high denitrification activity over five sequential cycles. Electrochemical impedance spectroscopy showed that coupling bio-FeS with strain LY15 markedly decreased the interfacial charge-transfer resistance. Furthermore, EPR, XPS, and iron-containing coating (Fe-coat) analyses suggested that the humic-like organic coating enriched in quinone moieties promoted persistent redox-active intermediates (e.g., SQ(center dot-)) and mitigated the accumulation of Fecoat on the bio-FeS surface. Furthermore, ATZ transformation proceeded via dechlorination, dealkylation, and hydroxylation pathways, driven by the synergistic electron supply from bio-FeS and microbial metabolism. This work establishes an efficient biomineralization pathway for producing bio-FeS and provides a sustainable bioremediation technology for the treatment of complex water pollution.

Co-contamination bynitrate-nitrogen (NO3--N)and heavy metals (HMs) can impair biological nitrogen removal. This study investigated whether powdered activated carbon (PAC) derived from coconut shell, applied at a trace dose, could enhance denitrification, manganese oxidation, and metal immobilization by Zoogloea sp. MFQ7 under HM stress. Under the selected conditions of pH 7.0, a carbon-to-nitrogen ratio of 1.5, and an initial Mn(II) concentration of 10.0 mg L-1, strain MFQ7 removed 92.89 % of NO3--N and 89.12 % of Mn(II). Addition of 0.8 mg L-1 PAC increased these removal efficiencies to 97.02 % and 97.11 %, respectively, while nitrite remained below 0.01 mg L-1. Under combined zinc (Zn(II)), copper (Cu(II)), and nickel (Ni(II)) stress, PAC maintained NO3--N and Mn(II) removal efficiencies at 75.93 % and 69.00 %, respectively, and achieved Zn(II), Cu(II), and Ni(II) immobilization efficiencies of 79.22 %, 78.65 %, and 71.34 %, respectively. PAC also increased electron transport system activity to a level 9.66 % above that of the unstressed control and helped preserve a matrix of extracellular polymeric substances (EPS) rich in proteins. Analyses of the solid phase showed that PAC introduced additional carbonaceous interfaces containing oxygen functional groups, while EPS, biogenic Mn precipitates, and metal carbonate phases contributed to metal immobilization. Overall, trace PAC derived from coconut shell alleviated inhibition caused by HMs through a combination of physiological protection and immobilization in the solid phase, supporting its exploratory application as an amendment derived from waste for complex wastewater treatment at the batch scale.

This study systematically investigated the effects of hydraulic retention time (HRT) on anaerobic ammonium oxidation (Anammox) performance by comparing nitrogen removal efficiency, enzymatic activities, EPS secretion and microbial community dynamics in a conventional reactor (R1) and a pyrite-assisted reactor (R2). Pyriteenhanced system achieved superior nitrogen removal (>90%) with an HRT of 12 h identified as optimal for both systems. Pyrite addition could facilitate electron transfer processes, microbial aggregation and biofilm formation, and enhance denitrification pathways, all contributing to improved system performance. Microbial community profiling further revealed that pyrite addition enriched overall community richness and diversity, and Candidatus Brocadia (anammox bacteria), OLB13, and Denitratisoma (denitrifying bacteria) were determined as key functional microorganism. Notably, Candidatus Kuenenia-a genus with high environmental adaptability-was exclusively detected in the pyrite-assisted reactor under shortened HRTs, indicating community succession to resist external stresses. Community assembly analysis revealed that the R2 system exhibited a stronger deterministic selection pattern and a more cooperative microbial network structure compared to R1, and overall findings showed that pyrite addition could promote the establishment of a more resilient and functionally stable microbial ecosystem under HRT shocking. This work could provide new insights into optimizing anammox systems for efficient nitrogen removal in wastewater treatment applications.

Microbially induced calcium precipitation (MICP) driven by denitrification provides a promising strategy for treating chemical wastewater with complex constituents, enabling the simultaneous removal of multiple contaminants. In this study, a mixture of tourmaline (Tm) and carbon nanotubes (CNTs) was employed as a facilitator and co-immobilized with Stutzerimonas sp. YX13 within hydrogel beads to construct an immobilized bioreactor. Under optimal operating conditions (HRT = 3 h, C/N = 5, and pH = 7), nitrate nitrogen (NO3 --N), orthophosphate phosphorus (PO43--P), calcium (Ca2+), copper (Cu2+), and ciprofloxacin (CIP) were removed with efficiencies of 91.81%, 88.38%, 79.91%, 97.71% and 98.61%, respectively. Microbial metabolites analysis revealed that the electric dipole properties of Tm stimulated the synthesis of humic-like and extracellular polymeric substances (EPS), thereby enhancing microbial tolerance to contaminant stress. Electron transport system activity revealed a significant enhancement of electron transport performance, attributable to the combined effects of the electrostatic field induced by the spontaneous polarization of Tm and the high electrical conductivity of CNTs. Electrochemical characterization further confirmed that incorporating Tm significantly enhanced the electron storage and transfer capabilities of the carrier material, providing strong support for the efficient removal of contaminants. Characterization of the bioprecipitates indicated that PO43--P, Ca2+, Cu2+, and CIP were predominantly removed via co-precipitation and adsorption mechanisms. This study provides a green and efficient strategy for the synergistic removal of multiple contaminants from chemical wastewater.

Anaerobic ammonium oxidation is a affordable and effective biological nitrogen (N) removal technique in wastewater treatment, but strict substrate ratio requirements and the slow growth of functional microorganisms prevent its widespread use. Iron (Fe), manganese (Mn), and sulfur (S), as redox-active elements, play pivotal roles in natural environments and wastewater treatment by facilitating microbial-mediated N transformation while mitigating greenhouse gas emissions. Therefore, novel anaerobic ammonium oxidation processes utilizing alternative electron acceptors like S, Fe, and Mn, known as Sulfammox, Feammox, and Mnammox, have been developed, opening new avenues for innovation in wastewater N removal. This review systematically summarized the discovery, mechanisms, functional microorganisms, and influencing factors of Feammox, Mnammox, and Sulfammox. It examines the potential of multi-element synergistic effects to improve denitrification efficiency and delineates their prospective applications in practical wastewater treatment. Notwithstanding their potential, obstacles persist in clarifying microbial metabolic networks, essential enzymatic processes, and comprehensive execution. Subsequent investigations ought to utilize interdisciplinary methodologies like as metagenomics and machine learning to enhance these operations. This review aims to offer theoretical support for the optimization and advancement of sophisticated anaerobic ammonium oxidation technologies, thereby aiding in the management of the global N cycle and the protection of aquatic environments.

As the complexity of industrial wastewater pollution continues to increase, the simultaneous removal of nitrogen, metal contaminants, and persistent organic pollutants under low carbon conditions has become a key challenge for biological treatment systems. To address the operational instability and dependence on carbon sources observed in immobilized systems when exposed to copper (Cu2+) and bisphenol A (BPA), the Pseudoalteromonas japonicus strain LY0623 was integrated into a hydrogel-biochar-AQDS composite carrier to construct a multifunctional immobilized biofilm system. Notably, under conditions containing only NaHCO3, the R4 system achieved an NH4+-N removal rate of 89%. Under conditions where Cu2+ and BPA coexist, the R4 system achieved removal of NH4+-N (89%), NO3--N (100%), Cu2+ (85%), and BPA (88%). Sediment characterization confirmed that Cu2+ was immobilized through adsorption, complexation, and microbiologically induced carbonate precipitation (MICP). Metagenomic analysis further indicated that the Pseudomonadota phylum remained the dominant phylum, while functional pathways associated with inorganic carbon assimilation, HNAD nitrogen metabolism, endogenous carbon transformation, biomineralization, electron transfer, and aromatic compound degradation were preserved. By combining ammonia oxidation driven energy production, inorganic carbon utilization, redox mediated processes, and biomineralization, this study provides a highly promising low carbon strategy for treating industrial wastewater containing mixed pollutants.

This study introduces high-performance self-lubricating epoxy composites incorporating bioinspired silica microcapsules. Fabricated via optimized oil-in-water emulsion, the microcapsules (8-22 mu m diameter, 0.5-0.6 mu m shell thickness) demonstrate excellent thermal stability (200 degrees C for 1 h) and high polyalphaolefin (PAO) encapsulation efficiency. At 5.0 wt% loading, the composite achieves outstanding tribological performance with an 89% reduction in both friction coefficient (from 0.56 to 0.08) and wear rate (from 120 to 13 x 10-6 mm3/Nm) under 5 N load, while retaining 85% of compressive strength. Microstructural analysis confirms uniform microcapsule dispersion and strong interfacial adhesion with the epoxy matrix. The composite exhibits a unique stress-responsive lubrication mechanism where mechanical triggers cause microcapsule rupture, releasing PAO to form continuous lubricating films combined with silica fragments. This dynamic process is quantitatively described by a conceptual kinetic framework model that accounts for stress-dependent rupture and lubricant entrainment. The excellent balance of tribological properties and mechanical integrity demonstrated under laboratory conditions makes these composites promising candidates for further investigation toward demanding applications.

Due to the limited availability of biodegradable organic carbon, low C/N wastewater often results in unsatisfactory denitrification efficiency and poor operational stability. Accordingly, methods for improved denitrification under low C/N conditions are needed. In this study, a novel three-dimensional biofilm electrode reactor (3D-BER) with Fe3O4, MnO2, and corncob (a solid slow-release carbon substrate) as a novel biofilm particle electrode was constructed for coupled ammonia nitrogen removal and denitrification in low C/N wastewater. At a current density of 0.1 mA cm-2, the system achieved a stable total nitrogen removal efficiency of 78%, stable nitrate removal efficiency of 87%, and coupled NH4+-N removal efficiency of 54%, outperforming the conventional solid-phase carbon source system. The superior electrocatalytic activity of the system was mainly attributed to the iron-manganese oxides acting as efficient electron shuttles. These oxides could function as electron acceptors to promote ammonia nitrogen oxidation and, in their reduced forms, as electron donors for nitrate reduction. They regulated microbial community structure, enhanced denitrification enzyme activity, and promoted the enrichment of functional microorganisms, ultimately enabling the efficient transformation and removal of multiple nitrogen species. The application of this novel iron-manganese-modified solid slow-release carbon particle electrode in the 3D-BER system facilitated rapid reactor start-up and significantly improved denitrification performance, demonstrating considerable potential for the advanced treatment of low C/N wastewater.