摘要 : This study challenges the view that glycogen-accumulating organisms (GAOs) solely hinder phosphorus removal in wastewater treatment. We investigated how GAOs influence phosphorus recovery in biofilm sequencing batch reactors (BSBRs) under varying carbon-to-phosphorus (C/P) ratios (20-40 mg-COD/mg-P) and dissolved oxygen (DO) levels (4-6 mg/L). By adjusting C/P and DO, we established systems with GAOs abundances ranging from 21.02 % to 2.49 % and polyphosphate-accumulating organisms (PAOs) abundances from 8.21 % to 25.73 %. Surprisingly, high GAOs abundance (21.02 %) correlated with superior phosphorus recovery (> 80 mg/L) and >95 % removal efficiency, contradicting conventional EBPR models. Metagenomic analysis revealed GAOs enhanced glycogen degradation and PHA synthesis, supporting energy-intensive phosphorus accumulation. Reduced GAOs abundance impaired acetate uptake and PHB polymerization, lowering system performance. GAOs also maintained microbial diversity and stabilized functional gene expression. We conclude that GAOs play a beneficial metabolic role in biofilm systems by optimizing carbon use for phosphorus enrichment, enabling stable recovery even when GAOs outnumber PAOs.

摘要 : Substrate inhibition remains a critical bottleneck for the stable operation and recovery of anaerobic ammonium oxidation (anammox) reactors. Although reducing influent substrate concentrations is the most commonly adopted recovery strategy, the appropriate reset point for restarting an inhibited reactor remains poorly understood. Here, using a continuous substrate-inhibited anammox granular reactor as a model system, we showed that severe inhibition occurred at influent ammonium and nitrite concentrations of 400 and 480 mg·L −1 , respectively. Notably, reducing the influent concentrations to 300 and 360 mg·L −1 , which had previously sustained stable high-rate nitrogen removal, was insufficient to restore reactor performance. Successful recovery was only achieved after further decreasing the influent concentrations to 150 and 180 mg·L −1 , respectively. Metatranscriptomic and genome-resolved analyses showed that the dominant anammox bacterium, Candidatus Kuenenia stuttgartiensis (AMX1), remained in a state of energy-metabolism dysregulation under substrate inhibition, as evidenced by significant upregulation of hydrazine dehydrogenase ( hdh ; log 2 FC = 1.78) and a markedly increased hydrazine dehydrogenase-to-hydrazine synthase subunit A ( hdh/hzsA ) ratio. Altered expression of NADH-ubiquinone oxidoreductase chain genes, together with adenylate energy charge measurements, further demonstrated that substrate inhibition trapped anammox bacteria in a low-energy state. By integrating adenosine triphosphate (ATP) levels, specific anammox activity, and substrate concentrations, we found that substrate inhibition caused a decoupling between substrate concentration and anammox activity. Overall, this study establishes a practical and reliable strategy for recovering substrate-inhibited continuous-flow anammox granular reactors dominated by Ca. Kuenenia stuttgartiensis and provides mechanistic insight into the energy-dependent basis of the reset point.

摘要 : This study introduces an accurate and efficient hybrid framework for fluid-structure interaction (FSI) that exploits the complementary strengths of smoothed particle hydrodynamics (SPH), the finite element method (FEM), and peridynamics (PD). SPH, a mesh-free Lagrangian method, is employed to model complex fluid flows characterized by large deformations and free surfaces, while solid domains are governed by a hybrid PD-FEM approach to reconcile computational efficiency with the ability to capture material failure. The main contribution is an element-wise adaptive FEM-PD transformation strategy, supported by a simplified partner ghost particle (PGP) coupling scheme for consistent information transfer across the PD-FEM interface. Driven by a critical bond stretch criterion, the scheme activates local FEM-PD transformation in regions where damage is expected to evolve. For fluid-solid interfaces, a binary ghost particle (BGP) scheme for SPH-FEM and a disguised ghost particle (DGP) scheme for SPH-PD are introduced. Both schemes accurately enforce interface conditions and provide consistent coupling at the multi-resolution interface. The feasibility and effectiveness of the proposed hybrid SPH-FEM-PD approach are demonstrated through benchmark problems involving structural dynamic deformation and fracture, hydrostatic problems, and FSI scenarios with structural failure.

摘要 : Thiourea can significantly inhibit the aerobic ammonia oxidation process, yet it can also serve as a multi‐electron donor in denitrification. Understanding the perturbational influence of thiourea on nitrogen removal in anaerobic ammonium oxidation (Anammox) systems is crucial for its application in treating high NH 4 + -N wastewater containing thiourea. Therefore, the present inquiry investigated its effects on nitrogen degradation pathways and microbial metabolism in Anammox systems. The findings reveal that when the influent thiourea concentration remains below 139.7 mg/L, both sulfur-oxidizing autotrophic denitrifiers (SOB) and their heterotrophic denitrifiers residing in the Anammox reactor fully metabolize this compound. They use NO 2 − -N/NO 3 − -N as electron acceptors, converting thiourea into SO 4 2− and NH 4 + -N. The activity of Anammox bacteria (AnAOB) was not significantly affected. However, the activity of the associated ammonia-oxidizing bacteria (AOB) was significantly inhibited, and nitrite-oxidizing bacteria (NOB) took over to mitigate the dissolved oxygen toxicity in the influent. The denitrifying microbial community in the Anammox system, originally dominated by AnAOB, shifted toward a multifunctional denitrifying community dominated by heterotrophic denitrifiers, SOB, and AnAOB. As thiourea concentrations increase, denitrifying microorganisms struggle to grow synergistically, leading to thiourea accumulation. Oxidative stress in the system rises, and catalase (CAT) activity is inhibited, resulting in cellular damage. Accumulated thiourea reduced the relative abundances of core genes hzs and hdh in AnAOB and sqr in SOB. Although the relative abundances of fccA / fccB in SOB and nirS in denitrifiers were upregulated, these potential functional changes could not counteract thiourea toxicity. AnAOB activity is restricted and cannot be restored in the short-term. Thiobacillus and Candidatus_Brocadia , as functional genera of SOB and AnAOB, respectively, exhibit abundance that varies with changes in nitrogen-sulfur transformation performance. Enhancing sulfur-autotrophic and heterotrophic denitrification to prevent thiourea accumulation is a key strategy for alleviating the denitrification stress imposed on the Anammox system.

摘要 : Existing reinforced concrete structures urgently require crack self-healing, yet conventional microbial electromigration may accelerate reinforcing steel corrosion. To address this issue, this study proposes a microbial electromigration-enabled self-healing strategy based on spore surface cationization. Poly(diallyldimethyl ammonium chloride) (PDDA) was self-assembled onto spores to construct a positively charged shell, reversing the zeta potential from −44 mV to +32 mV. This enables directional migration of spores toward the reinforcing steel (cathode) under a direct current electric field, while substantially mitigating the damage to both the mortar matrix and steel during electromigration. The number of spores transported into mortar by electromigration was approximately 5 times that achieved by natural diffusion, and their metabolic activity remained unaffected. After 10 wet–dry cycles, cracks with various widths (≤600 μm) were almost completely healed. Meanwhile, the water permeability coefficient decreased by approximately 3–4 orders of magnitude, indicating a pronounced recovery of impermeability. In addition, excellent corrosion protection was achieved for embedded steel, with the mass loss reduced to 0.05 wt%, corresponding to an 85% decrease compared with the reference. Electrochemical impedance spectroscopy further revealed a marked increase in charge transfer resistance at the steel/mortar interface after healing, confirming the enhanced corrosion resistance of the reinforcement. This study provides an effective technical pathway for the self-healing of existing reinforced concrete structures.

摘要 : This study systematically investigated the phosphorus (P) adsorption and release behaviors of biofilm extracellular polymeric substances (EPS) in a sequencing batch biofilm reactor (SBBR). Batch experiments, enzyme activity assays, P forms, and spectral characterizations (3D-EEM, FTIR, XPS) were integrated to elucidate the independent role of EPS in biofilm P metabolism. The results quantified the independent P adsorption and release capacities of EPS as 1.68 mg/g and 2.46 mg/g, respectively. Different from cell-dependent biological P metabolism, EPS-mediated P transformation was insensitive to dissolved oxygen variation and carbon addition, and was mainly dominated by physicochemical adsorption. EPS-derived orthophosphate (Orth-P) and polyphosphate (Poly-P) contributed over 67% and less than 12% to the total Orth-P and Poly-P metabolism of biofilms, respectively. Although polyphosphate kinase (PPK) and polyphosphate hydrolase (PPX) activities were detected in EPS, the lack of effective carbon utilization capacity restricted their involvement in Poly-P transformation. Metal-mediated complexation served as the core immobilization pathway, in which Ca 2 + and Mg 2 + bound with phosphate groups, as well as carboxyl and amino functional groups of tryptophan- and tyrosine-rich proteins in EPS. Beyond the inherent physicochemical adsorption properties of EPS, microbial cells further regulated EPS content by aerobic biosynthesis and anaerobic biodegradation. Such microbial regulation synergistically optimized the P adsorption-release performance of EPS, verifying that EPS acts as the dominant functional component responsible for P transformation in biofilm systems. This study clarifies the intrinsic mechanisms underlying EPS-mediated P adsorption and release, and provides a theoretical basis for the development of low-carbon and high-efficiency P recovery technologies.

摘要 : The existing low-light image fusion methods adopt step-by-step operation to improve the overall luminance of the fused image, which leads to the degradation of infrared salient information, modal incompatibility, and fails to address the issue of color deviation. To overcome the above drawbacks, a unified fusion framework is designed in this paper, that is, a knowledge distillation based scene enhancement and color preservation for infrared and low-light image fusion method (UIKDF). Specifically, a dual-stream teacher-student parallel architecture is constructed with the low-light image enhancement network as the teacher stream and an image fusion two-branch network as the student stream. The coupled feature distiller(CFD) is designed to group the teacher-enhanced knowledge and purposefully pull it into the same space as the visible branch of the student model, to ensure that the student model learns scene detail enhancement and is combined with logit distillation for increased efficiency. Secondly, a cascading semantic enhancement optimization mechanism (CSEM) is introduced into the infrared branch of the student network to capture the aggregation of multi-level salient information. In addition, a weighted cross-modality fusion module (WCMF) is developed to dynamically integrate the infrared salient information and the visible detail using the learning weighted graph to further improve the fusion performance. It is worth noting that in order to achieve simultaneous luminance enhancement and chrominance restoration, a transform domain loss function optimization scheme (TD-LossOpt) is proposed. The model is processed in the RGB space, but the loss function is calculated in the YCbCr space, where a gradient-weighted color loss is designed in the CbCr color channel to preserve the scene color. Compared with the existing state-of-the-art fusion methods, the proposed method has better performance in terms of both visual evaluation and objective evaluation on public datasets. The source code is available at https://github.com/lxq-jnu/UIKDF .

摘要 : Dissolved organic matter (DOM) plays a key role in influencing the environmental behavior of heavy metals in lake ecosystems. Through mechanisms such as complexation, ion exchange, and physical adsorption, DOM regulates the speciation, transport, and bioavailability of heavy metals, thereby shaping their ecological risks and fate. Here, we provide a comprehensive review of the sources and molecular composition of lake DOM, with particular attention to humic substances, proteins, and polysaccharides, and highlight the importance of functional groups such as carboxyl group and phenolic hydroxyl group in metal binding. The mechanisms of DOM-heavy metal interactions are discussed in detail. These include σ-ligand bonding, which relies on the donation of lone pair electrons from O/N-containing functional groups to metal orbitals. Also covered are π–d electron interactions, often initiated by photoexcitation of aromatic moieties in DOM to facilitate electron transfer, and multi-site adsorption, a process governed by the combined effects of electrostatic attraction, hydrogen bonding, and the porous structure of DOM. Additionally, the effects of environmental factors (temperature, pH, and light) and biological factors (microbial activity and aquatic plant decomposition) on DOM-heavy metal dynamics are examined. Although substantial progress has been made, key challenges remain in understanding the microscale mechanisms, capturing real-time changes in natural waters, and assessing long-term ecological impacts. Future research should prioritize multi-scale approaches. This entails employing advanced techniques like Fourier-transform ion cyclotron resonance mass spectrometry to elucidate molecular mechanisms, while also advancing in situ monitoring technologies and establishing long-term observation networks to resolve real-time dynamics and assess cumulative ecological impacts. This review provides a theoretical basis for understanding DOM-heavy metal interactions and supports future efforts in ecological risk assessment and the sustainable management of lake environments.

摘要 : Compared to the effects of cavity mirror thermal deformation, cavity mirror misalignment, and the non-uniform distribution of the gain medium on laser beam quality, atmospheric disturbances have a more disruptive influence on laser beam quality. In order to investigate this effect, the variation of laser beam quality during the atmospheric transmission process was simulated and calculated under different parameters in the GLAD software environment. The calculation parameters primarily include the output laser power density, laser wavelength, atmospheric coherence length, altitude of the laser emission point, and focal length of the focusing mirror. The simulation results showed that: (1) As the output laser power density increases, the atmospheric perturbation effects such as atmospheric turbulence, thermal blooming, and wind speed become more pronounced, the laser beam diffuses at the irradiated target location, the spot appears fragmented, and the laser beam quality gradually deteriorates, the actual focus position of the laser gradually shifts forward, and when the output laser power density increases from 100W/cm2 to 2000W/cm2, the corresponding focus moves from 3.0km to 1.6km. (2) The longer the laser wavelength, the better the laser beam quality, and the Strehl ratio corresponding to the 1.315μμμm wavelength is approximately twice that of the 0.85μμμm wavelength. (3) As atmospheric disturbance increases, the laser power density distribution at the irradiated target location begins to exhibit discrete peaks, and the laser beam quality gradually decreases. It is found that when the atmospheric coherence length exceeds 20cm, the laser intensity distribution gradually approaches an ideal state. In addition, with the increase in atmospheric coherence length, the actual laser focus position gradually shifts back when the atmospheric coherence length increased from 5cm to 10cm, the corresponding focus position moved from 2.0km to 3.0km, closer to the geometric focus position.(4) As the altitude of the laser emission point increases, the focusing effect of the laser spot improves, and the laser intensity distribution becomes closer to the ideal far-field distribution. The actual focus position of the laser gradually shifts back, when the altitude increases from 0km to 7km, the focus moves from 2.0km to 2.9km, which is closer to the geometric focus position, and the efficiency of the laser also increases. In addition, when the altitude increases from 3km to 7km, the corresponding laser power density and beam quality increase by 1.7times and 3.5times, respectively. (5) As the focal length of the focusing mirror increases, the laser beam quality improves gradually, and the atmospheric transmission quality of the laser also enhances progressively. These findings provide guidance for pre-correction of adaptive optics systems in lasers and for assessing long-distance laser transmission efficiency.

摘要 : Electroactive membranes can dynamically regulate interfacial properties using external electric potentials, which offers a feasible approach to preventing fouling and controlling selective separation performance in water treatment. However, current pre-programmed control modes struggle to adapt to the dynamic changes in membrane interface states, fouling characteristics, and water quality during filtration processes. Improper regulation may lead to suboptimal performance, increased energy consumption, and even accelerated membrane aging. This paper argues that transitioning from static functional materials to environmentally adaptive intelligent systems is the key pathway to unlocking the potential of electroactive membranes. We propose evolving from pre-programmed execution to intelligent operation based on “real-time sensing-prediction-optimization”. By diagnosing microfouling early and identifying intrinsic characteristics, we can predict the quantitative impact of regulatory measures on short-term performance and long-term lifespan. Through continuous self-evolution, the system actively seeks global optimal solutions, synergistically maximizing separation stability and material longevity while minimizing energy consumption footprint. This paper systematically outlines the theoretical foundation, core components, and operational logic of this intelligent framework, while identifying key future research directions and technological development pathways.