Volatile sulfur compounds (VSCs) are malodorous and hazardous gases, which are generated during the anaerobic digestion (AD) of waste activated sludge (WAS). Iron can mediate sulfur transformation during AD process. The evolution and distribution of sulfur across the gas-liquid-solid phases in the presence of ferric chloride (FeCl3) remain poorly understood. In this study, semicontinuous anaerobic digesters were employed to decipher iron-mediated interactions in sulfur dynamics during the AD of WAS. The results showed that FeCl3 significantly decreased the generation of all kinds of VSCs (a total removal of 69%), shifting chemical equilibrium from VSCs to solid inorganic sulfur. It also enhanced the degradation of both solid organic sulfur and soluble organic sulfur, but reduced the production of soluble sulfide by forming more acid volatile sulfide and S0 in the solid phase. The generated soluble sulfide was immediately removed in two ways: 85% precipitated as FeS by Fe(II) ions derived from dissimilatory iron reduction, and 15% oxidized to S⁰ by Fe(III) or sulfur-oxidizing bacteria (SOBs). Microbial community analysis confirmed that the presence of FeCl3 increased the abundance of hydrolysis and acidification bacteria, iron-reducing bacteria and SOBs but reduced the relative abundance of sulfate-reducing bacteria. This resulted in efficient hydrolysis of organic sulfur, increased oxidation of soluble sulfide, and weakened reduction of soluble sulfate. By deciphering the multiphase fate of sulfur during AD, this study provides critical insights for controlling VSCs generation in sludge management.

Forward osmosis (FO) represents an energy-efficient membrane separation process that leverages osmotic pressure gradients for water treatment. Nevertheless, fouling induced by dissolved organic matter (DOM) remains a major obstacle to its practical application, underscoring the need for a deeper mechanistic understanding to enable effective fouling mitigation. This study systematically investigates FO membrane fouling mechanisms using the collision-attachment (CA) model as an analytical and predictive framework. Model foulants, including tannic acid (TA), sodium alginate (SA), bovine serum albumin (BSA), and natural DOM, were employed to elucidate the fouling behavior under varying hydrodynamic conditions, membrane orientations, and foulant concentrations. The CA model successfully unveiled fouling mechanisms, transitioning from foulant-membrane interactions at low total organic carbon (TOC <= 20 mg/L) to foulant-foulant interactions at high concentrations (TOC = 100 mg/L). Among the tested foulants, BSA and TA exhibited stronger fouling tendencies than SA. The active-layer-toward-draw-solution (AL-DS) configuration showed a higher initial flux but suffered more fouling development. Moreover, the validated CA model was effective in predicting natural DOM fouling under low TOC and low flux conditions. This investigation may provide mechanistic insights into FO membrane fouling and establish a validated framework for performance prediction and process optimization, contributing to more sustainable and efficient FO-based water treatment systems.

Mesoporous biochar activated with potassium bicarbonate (KHCO3) is more conducive to mass transfer, but the effects of its weak alkalinity in conjunction with mesoporous structures on anaerobic digestion (AD) of waste activated sludge (WAS) remain underexplored. In this study, sludge-derived mesoporous biochar (SMBC) was synthesized using KHCO3-activated sludge that had undergone ball milling or impregnation pretreatments. The obtained SMBC featured large mesopores (38.349-44.325 nm), abundant CO functional groups and defect sites. Compared to the control, SMBC increased the maximum cumulative methane yield by 74.97 % (104.58 vs. 59.77 mLgVS(-1)) and the maximum methane production rate by 139.71 % (5.01 vs. 2.09 mL center dot gVS(-1)d(-1)), while the apparent electron-transfer constant rose 6-fold (0.036 vs. 0.006 s(-1)). In the SMBC groups, carbon and energy metabolism were enhanced via establishment of intracellular and extracellular electron transport, as supported by increased INT-ETS activities (10.11-15.80 %), hydrogenase activities (22.48-33.41 %), and cytochrome C concentrations (14.62-31.44 %), along with alterations in extracellular polymeric substances composition (more humic acids-like compounds). Microbially, g_norank_f_Bacteroidetes_vadinHA17 and electroactive microorganisms were enriched in the SMBC groups, and the expression of key methanogenesis-related enzymes (Mcr, Fwd, MtbB etc.) was upregulated. Correlative analyses indicated that the mesoporous structure and alkaline-slow-release characteristics of SMBC jointly steered microbial community composition and functional gene expression (p < 0.05), thereby enhancing methanogenesis. This study establishes an innovative strategy for valorizing WAS into engineered biochar and its subsequent reinjection as a functional additive to intensify energy recovery during the AD process, thereby advancing carbon-neutral resource utilization.

Wastewater treatment plants (WWTPs) serve as critical reservoirs and dissemination hotspots for pharmaceuticals and antibiotic resistance genes (ARGs), posing significant threats to environmental and public health. In this study, a novel riboflavin/ultraviolet/peracetic acid (RF/UV/PAA) disinfection process was developed to enhance the removal of these emerging contaminants. The process achieved superior performance in degrading 29 pharmaceuticals and eliminating 106 ARGs and 13 mobile genetic elements (MGEs), attributed to the action of both radical and non-radical species. The underlying risk mitigation potential was further elucidated through multiomics analyses. The results revealed that the RF/UV/PAA process suppresses ARG dissemination through a triple-mechanism pathway, directly inactivating host bacteria; blocking vertical gene transfer; enhancing pharmaceutical removal, which alleviates the selection pressure for resistance; and disrupting horizontal gene transfer (HGT) through MGE destruction and alterations in membrane permeability, extracellular polymeric substance secretion, adenosine triphosphate synthesis, and cellular motility. Notably, our results also suggest that non-antibiotic pharmaceuticals promote the MGE-mediated HGT of ARGs, challenging the conventional antibiotic-centric paradigm. This study not only establishes RF/UV/PAA disinfection as an effective technology for the synergistic removal of pharmaceuticals and ARGs in wastewater but also provides critical mechanistic insights to mitigate ARG dissemination via WWTP effluents.

Zinc ions play an important role in environmental monitoring and zinc-based energy storage devices. However, simultaneously achieving specific fluorescent detection of Zn2+ and suppressing dendritic growth on zinc anodes using a single material remains a formidable challenge. In this investigation, we designed and synthesized a series of aromatic polyacylhydrazones featuring nitrogen and oxygen coordination sites for Zn2+ specific detection and anode protective coating. Among the three polyacylhydrazones, the representative PIH-T exhibits specific Zn2+ detection through the chelation-enhanced fluorescence effect (CHEF) with exceptional fluorescence stability. Even in the presence of 13 common cations and 10 anions, PIH-T selectively distinguishes Zn2+ with the detection limit of 0.16 μM and the binding stoichiometry of 2:1. More importantly, PIH-T as a protective coating on zinc anodes effectively regulates Zn2+ deposition, substantially suppressing dendrite formation, which enables a threefold increase in the cycle life for zinc-ion hybrid supercapacitors (ZHSCs). The serial electrochemical characterization and SEM morphological analysis reveal that, compared with Bare Zn, the PIH-T coating layer enables a uniform, dense zinc surface with no observable dendrites, maintaining the structural integrity and chemical stability even after prolonged cycling. In brief, the single PIH-T not only enables sensitive and selective Zn2+ detection but also demonstrates great potential as a protective coating layer on zinc anodes in ZHSCs.

The looming depletion of global phosphate rock reserves necessitates an urgent transition to phosphorus (P) recovery from secondary resources. Wet waste represents a massive yet largely untapped reservoir of P in China. However, efficient P extraction is constrained by the complex and heterogeneous speciation of P within these waste matrices. This review comprehensively examined P speciation in wet waste, emphasizing the predominance of inorganic fractions and the structural challenges posed by organic forms, particularly phytate and phosphate esters. Advanced analytical techniques were summarized to bridge the knowledge gap between speciation and practical recovery. Building on this foundation, recovery approaches-including liquid-phase crystallization, pyrolysis, biochar adsorption, and bioconversion-were discussed, and the operational efficacy of targeted extraction methods (hydrothermal, chemical, electrochemical, and biological) was specifically summarized. Quantitative comparisons show that mono-digestion of fiber-rich waste achieves only 26.2% P recovery versus 40.8% for protein-rich substrates, whereas co-digestion can elevate recovery to 88.3%. Additionally, pyrolysis retains > 90% total P, microalgae remove 93.4%, electrodialysis achieves > 90%, and liquid-phase crystallization enables near-complete (∼100%) recovery under optimized conditions. Crucially, the thermodynamic mechanisms underlying P migration during recovery were explored. Through evaluation of each technology's performance against both labile and recalcitrant P fractions, the main challenges were identified as low recovery from fiber-rich substrates and economic scalability barriers. Priority future directions centered on plant-available P recovery and integrated multi-technology coupling were proposed. This study offers a theoretical basis and technical reference for sustainable P reclamation from wet waste, contributing to alleviating global P scarcity and achieving environmental protection.

Microplastics (MPs) are known to promote antibiotic resistance gene (ARG) dissemination in waste activated sludge; however, most existing evidence is based on unaged MPs, and the influence of aging degree remains poorly understood. This study systematically investigated how varying aging degrees of polyethylene (PE) and polypropylene (PP) MPs modulate ARG profiles and transfer mechanisms during anaerobic digestion. The results demonstrated a non-monotonic effect of aging degree on ARG proliferation, with moderate aging of MPs showing the strongest attenuation of ARG promotion. Under moderate carbonyl indices (CI) of 0.104 for PE-MPs and 0.219 for PP-MPs, the average reduction of the most affected ARGs reached 40% and 50%, respectively, compared with the unaged MPs. Metagenomic analysis further revealed that moderate aging of MPs reduced both the abundance and diversity of ARGs stimulated by unaged MPs. Mechanistically, unaged MPs induced multiple biological responses. These included enrichment of dominant ARG-hosting genera within Proteobacteria and Chloroflexi, elevated oxidative stress, increased membrane permeability, and activation of horizontal gene transfer (HGT) pathways, including the type IV secretion system (T4SS), quorum sensing (QS), and two-component systems (TCS). Conversely, aging weakened these microbial signaling and stress responses at moderate aging degrees but led to a rebound at higher aging degrees, thereby modulating HGT potential in a non-monotonic manner. These findings indicate that aging of sludge-relevant MPs (PE and PP) fundamentally alters their ecological impact on the sludge resistome, highlighting the necessity of incorporating aging dynamics into the risk assessment of MPs in engineered ecosystems.

In this study, a novel riboflavin-mediated ultraviolet/peracetic acid system (RF/UV/PAA) was developed to enhance the degradation of ranitidine. Under optimal conditions, ranitidine was completely removed within 15 min, leading to a 68.9% mineralization rate due to the combined action of radical (hydroxyl radicals (·OH) and carbon-centered organic radicals (R-C·) and nonradical (singlet oxygen (1O2)) reactive oxidative species (ROS). Electron paramagnetic resonance and quenching experiments indicated that RF significantly promoted ROS generation, with the respective contributions of ·OH, R-C· and 1O2 to ranitidine removal being 54.5%, 15.8%, and 24.3%, respectively. Demethylation, monooxygenation, dioxygenation, and C-S bond cleavage were identified as the primary degradation pathways for ranitidine. These pathways were initially inferred from structural analysis of transformation products (TPs) and subsequently validated through density functional theory (DFT) calculations and the TP-Transformer model. Furthermore, an integrated DFT-machine learning (ML) framework was employed to elucidate the degradation mechanism, with a specific focus on the interactions of principal molecular features with ROS. The results revealed that FractionCSP3 (SHAP value = 0.30) and MolWt (SHAP value = 0.44) were the dominant predictors of ·OH and 1O2 reactivity, respectively, whereas FormalCharge (SHAP value = 0.40) governed the R-C·-mediated processes. In addition, SHAP-based interaction analysis revealed that electron-rich sites facilitate ·OH attack, conjugated π-systems promote 1O2 reactivity, and molecular polarization drives R-C· reactions. Our study provides not only an effective technology for ranitidine removal but also a quantitative, interpretable framework for predicting reactivity and guiding the design of photo-assisted advanced oxidation processes.

Antibiotic resistance genes (ARGs) often persist or rebound after food waste (FW) composting. Key species (Thermobifida fusca and Saccharomonospora viridis) are considered a promising strategy for mitigating ARGs by strengthening cooperation potential. However, their effects on ARGs dynamics during composting remain unclear. To address this, three composting treatments were conducted: inoculation with both key and functional species (TA), inoculation with functional species only (TB), and an uninoculated control. Compared with Control, TA significantly prolonged the thermophilic period by 3.4 times and increased the humification rate by 1.3 times. After composting, TA exhibited a 55.1% reduction relative to the initial relative abundance before composting, reaching 0.39 copy/cell. In contrast, the relative abundance of total ARGs increased by 1.3-fold in the Control (0.62 copy/cell). Moreover, TA exhibited a reduction in mobile ARGs from 0.19 to 0.08 copy/cell, whereas the Control increased from 0.11 to 0.16 copy/cell, and TB remained relatively stable (∼0.16-0.17 copy/cell). These key species successfully colonized in TA, with relative abundances 20.0-158.7 times higher than that in Control, and were identified as key hubs in networks, enhancing the proportion of positive edges by 1.2 times. Overall these results suggested that introducing key species into a functional inoculum was associated with enhanced potential positive associations, improved humification, and reduced diversity, relative abundance, and mobility of ARGs.

Aluminum-phosphorus (Al-P) compounds are byproducts of chemical phosphorus removal in wastewater treatment plants (WWTPs), resulting in their accumulation in waste activated sludge (WAS). However, their effects on the anaerobic digestion (AD) of WAS remain poorly understood. This study investigated the effects and underlying mechanisms of Al-P on WAS anaerobic digestion. The results showed that Al-P enhanced methane production, with increases of 19.16% and 48.09% at dosages of 100 and 500 mg Al/g TS, respectively. Mechanism analysis indicated that Al-P reconfigured sludge physicochemical properties by binding with Ca2+ and Mg2+, releasing extracellular polymeric substances (EPS), reducing sludge particle size, and increasing the proportion of internal water, thereby promoting sludge dispersion and floc disintegration. Interfacial thermodynamic analysis indicated that Al-P modified sludge surface properties by increasing acid-base interaction energy and the flocculation energy barrier. The total interaction energy of sludge particles rose from -15.26 mJ/m2 in the control to 85.55 mJ/m2 at an Al-P dose of 500 mg Al/g TS, which quantitatively confirmed sludge disintegration. Such structural and thermodynamic reconfiguration elevated the activities of key enzymes involved in hydrolysis, acidogenesis, and methanogenesis. Microbial analysis revealed that Al-P addition enriched both acetoclastic and hydrogenotrophic methanogens, as well as syntrophic bacteria that support hydrogenotrophic methanogenesis. Analyses of functional genes and metabolic pathways further corroborated that Al-P promoted both acidogenesis and the methanogenesis. This study provides novel insights into the potential of Al-P as an effective interfacial regulator for enhancing methane production and promoting sustainable bioenergy recovery from WAS.

Nanofiltration (NF) for advanced drinking-water treatment has long been constrained by the need to remove contaminants while preserving beneficial mineral ions in health-oriented drinking water. Herein, an ethylene-glycol (EG)-regulated aqueous microenvironment was introduced to tailor the interfacial polymerization process. EG-mediated hydrogen bonding and modified interfacial thermodynamics jointly regulated piperazine diffusion, interfacial transport, and polymerization kinetics, producing polyamide NF membranes with enhanced negative charge surface density and a more uniform effective pore structure. Compared with the pristine membrane, the EG-20 membrane exhibited a thinner, more hydrophilic, and more negatively charged selective layer, together with a narrower pore-size distribution. The optimized EG-20 membrane achieved a permeance of 23.6 L m−2 h−1 bar−1 while maintaining Na2SO4 rejection above 95.5%. In the treatment of natural surface water, dissolved organic matter removal reached approximately 92.1%, while partial passage of beneficial mineral ions was maintained, enabling effective organic contaminant removal with mineral preservation for health-oriented drinking water treatment. Moreover, high rejection of PFAS and antibiotics was maintained, mainly because steric exclusion and enhanced electrostatic repulsion compensated for the moderately enlarged effective pores. In addition, the membrane showed improved antifouling performance, as enhanced surface hydration and electrostatic repulsion reduced foulant adhesion and suppressed irreversible fouling. Overall, this microenvironment-regulation strategy provides a feasible route for developing NF membranes that integrate effective contaminant control, mineral preservation, and stable operation.

Nitrogen removal and enhanced biological phosphorus removal (EBPR) are inherently incompatible in conventional anaerobic-anoxic-aerobic (A2O) systems due to competition for carbon sources and differences in microbial growth requirements. To address this challenge, a strategy coupling return sludge side-stream fermentation (SSF) with a shortened sludge retention time (SRT) was employed to achieve simultaneous shortcut nitrogen removal (SNR) and EBPR. The results indicated that at an SRT of 6 d, the removal efficiencies of COD, PO43−-P, and TN reached 90.6%, 80.1%, and 83.7%, respectively, with a 32.0% nitrite accumulation rate. Kinetically, the ratio of the specific ammonia oxidation rate to the specific nitrite oxidation rate remained at 1.30, while the specific phosphorus uptake rate increased greatly. As the SRT was progressively shortened, nitrite-oxidizing bacteria were suppressed then partially recovered, whereas denitrifying bacteria generally increased, and multiple lineages of polyphosphate-accumulating organisms jointly supported EBPR stability. Metagenomic analysis revealed an increased nirKS/(narGHI + napAB) ratio, indicating preferential electron flow toward shortcut denitrification. Moreover, stable abundances of ppk1 and phaC indicated a robust phosphorus metabolism. This study highlights the pivotal role of SRT control in A2O-SSF systems for the integration of SNR and EBPR, providing novel insights into the optimization of energy-efficient wastewater treatment processes.

Conventional supported catalytic membranes (CM) encounter three core bottlenecks in water treatment applications: catalyst leaching, insufficient mass transfer efficiency, and pore blockage. The integration of confined catalytic materials with membrane separation technology has emerged as a transformative strategy to address these limitations. This coupled system enables the simultaneous deep degradation of refractory pollutants in aqueous matrices and in-situ mitigation of membrane fouling, thereby providing a promising avenue for the technological upgrading of advanced water treatment processes. Despite the compelling technical merits of this integrated system, the absence of a systematic and comprehensive theoretical framework remains a critical research gap, which severely hinders its large-scale engineering implementation and industrial deployment. Herein, we first provide a systematic overview of the latest material systems for confined catalytic membranes and clearly elucidate their functionalization strategies and AI-assisted methods for confined catalysis. Subsequently, we conduct an in-depth investigation into the multi-process coupling mechanisms underpinning confined catalytic membranes, with a particular focus on the core confinement effects governing system performance: mass transfer-reaction synergy, interfacial electron transfer and regulation, and in-situ membrane fouling mitigation mechanisms. Building on this mechanistic understanding, we have provided a detailed explanation of the construction of a system model that couples confined catalysis with membrane separation technology. In parallel, we comprehensively map out the typical application scenarios of this coupling technology in water treatment, along with the currently established performance evaluation frameworks. Finally, we identify and discuss the key frontier scientific challenges and future research priorities in this field. Overall, this review aims to advance the systematic understanding of the structure-function relationships and rational design principles of confined catalysis-membrane separation coupling systems, with the ultimate goal of providing fundamental theoretical insights and actionable technical guidance to accelerate the engineering translation and industrial-scale deployment of this promising technology in sustainable water treatment.

Ultrafiltration (UF) has emerged as a promising clean technology for mariculture wastewater treatment, while conventional polysulfone (PSF) UF membranes suffer from severe membrane fouling and high manufacturing costs. Meanwhile, massive end-of-life reverse osmosis (RO) membranes pose critical solid waste disposal challenges. Herein, a one-step controllable sodium hypochlorite (NaClO) oxidation strategy was developed to upcycle waste RO membranes into hydrophilic anti-fouling UF membranes, realizing synchronous degradation of the aromatic polyamide (PA) active layer and in-situ hydrophilic functionalization of the PSF support layer. At the optimal oxidation intensity of 300,000 ppm·h, abundant carboxyl and sulfonic acid groups were formed on the PSF membrane, raising the polar component of surface energy from 3.95 mJ·m−2 (the pristine PSF membrane) to 16.65 mJ·m−2. Ten-cycle fouling-regeneration tests with humic acid as the model foulant showed the recycled PSF membrane yielded a superior flux recovery rate (FRR) of 88.15% and a flux decline rate (FDR) of 25.44%, compared with 30.17% FRR and 71.41% FDR of the pristine PSF membrane. The cross-flow modified Hermia's models fitting results confirmed the membrane fouling was dominated by the reversible cake layer filtration model with a higher R2 of 0.9998, as the hydrophilic barrier effectively prevented foulants from intruding into membrane pores. For real mariculture wastewater treatment, it exhibited a chemical oxygen demand (COD) removal efficiency of ca. 62% and reduced the permeate COD to 2.78 mg·L−1, meeting the national discharge standard (< 3.0 mg·L−1). Economic evaluation revealed its unit fabrication cost of 2.15 USD·m−2, over 90% lower than the market price (25–40 USD·m−2) of commercial PSF UF membranes. Distinct from conventional anti-fouling modification routes relying on expensive nanofillers or complex blending processes, this work achieved waste RO membrane valorization and anti-fouling functionalization via a single immersion step in NaClO solution at pH 11, providing a novel, cost-effective and sustainable pathway for developing anti-fouling UF membranes for mariculture wastewater treatment.

Proteins and polysaccharides are the predominant organic fractions of waste activated sludge (WAS). However, the regulation mechanisms of their distinct molecular structures and compositional ratios on the efficiency of anaerobic digestion (AD) remain unclear. This study comprehensively investigates their impacts on AD performance, focusing on molecular thermodynamics and functional gene regulation involved in electron transfer, energy conversion, and methanogenic pathways. The results demonstrate that molecular structure is a key factor determining substrate bioavailability. The protein with a mainly β-structure (xylanase) and randomly coiled polysaccharide (pullulan) exhibited superior hydrolysis, acidification, and methanogenic efficiency due to increased enzyme binding affinity. Conversely, α-helical protein and triple-helix polysaccharide displayed restricted enzymatic accessibility. Further studies revealed the combination of xylanase and pullulan at the optimal C/N ratio (35) effectively balanced nutrition, thereby achieving the highest cumulative methane yield. Metagenomic and metatranscriptomic analyses revealed that the optimal structures and C/N stoichiometry not only enriched GH13 enzymes, but also shifted the metabolic pathway from acetoclastic to hydrogenotrophic methanogenesis. Moreover, it enhanced interspecies electron transfer and energy conversion efficiency by promoting NADH dehydrogenases, formate dehydrogenase and heterodisulfide reductase, thereby establishing a highly efficient and stable metabolic network in AD system. These findings provide novel insights into the microbial and biochemical regulation driven by substrate structure and stoichiometry from cross-scale perspective, thereby offering a theoretical basis and regulatory strategy for the efficient resource recovery of waste activated sludge.

This study systematically evaluated the effects of nongelatinous and gelatinous extracellular polymeric substances (ngEPS and gEPS) on the anaerobic digestion performance of waste activated sludge (WAS). Extraction of ngEPS and gEPS enhanced methane production by 10.6 and 51.6%, respectively. Additionally, the process enabled the recovery of high-value resources such as alginate-like exopolysaccharides (ALE, a key polysaccharide component of gEPS) at concentrations in the range of 14.0-57.20 mggVSEPS -1 and phosphorus (P) accounting for approximately 40.0-61.2% of the total P content in WAS. Mechanistic analyses revealed that hydrophobic EPS components hindered WAS hydrolysis, whereas EPS extraction improved fluidity, reduced viscoelasticity, and promoted mass transfer efficiency. Metagenomic results further demonstrated that EPS extraction alleviated hydrolysis limitations, enriched acidogenic bacteria, and restructured microbial communities toward enhanced carbon metabolism. These findings provide both theoretical insights and practical guidance for advancing anaerobic digestion efficiency and resource recovery from WAS. The study highlights the potential of EPS-targeted strategies to optimize WAS management practices, contributing to the development of more sustainable and circular resource recovery systems.

Polyamide (PA) nanofiltration (NF) membranes represent a promising approach to safe drinking water production. Yet, selective removal of contaminants while retaining essential minerals remains a critical challenge for cost-effective water treatment processes. Here, we employed ammonia bicarbonate (AB) as an economical additive to modify interfacial polymerization (IP) for developing high-performance NF membranes suitable for drinking water applications. Comprehensive characterization coupled with molecular dynamics simulations demonstrate that AB modulates the IP process through three mechanisms: (1) controlling the diffusion kinetics of piperazine (PIP) at the aqueous-organic interface, (2) the reaction between HCO3- and H+ produced by IP achieves nanofoaming, and (3) the thermal decomposition of AB releases additional gaseous products (NH3 and CO2), enhancing the dual nanofoaming effect. This controlled reaction kinetics and increased nanobubble formation produced a thinner, more wrinkled PA selective layer with an optimized microstructure. The optimized NF-AB-8 membrane demonstrated enhanced permeance (28.5 LMH/bar) during actual surface water purification, while maintaining selective separation between minerals and dissolved organic matter (KCa2+/DOM = 34.5). In addition, the improved microstructure and separation performance enhanced the antiscaling and antifouling properties of the NF membrane. This study explored the application of dual-nanofoaming mechanisms in NF membranes, providing insights for designing NF membranes that simultaneously improve permeance and selectivity, which may promote the preparation of high-performance NF membranes and their application in drinking water production.

Polyamide (PA) nanofiltration membranes (NFMs) possess highly crosslinked structures, leading to several technical limitations such as poor selectivity, low permeance, and severe fouling. This study devised a novel isopropanol (IPA)-induced decrosslinking strategy to systematically modulate PA crosslinking density by precisely controlling IPA concentration and temperature. IPA induces swelling effects and hydrogen bonding, selectively extracting loosely crosslinked PA chain segments and allowing for network relaxation and rearrangement to form a uniform structure with lower overall crosslinking density. The optimised NF membrane post-treated with IPA at 60 °C (NF-IPA@60) achieved 32.94 % decrosslinking with enhanced surface negative charge density and enlarged pore size. Compared to the control membrane (NF-H2O), NF-IPA@60 exhibited higher pure water permeance (27.3 LMH/bar) while maintaining 92.7 % Na2SO4 rejection. Enhanced Donnan exclusion significantly improved micropollutant removal, particularly for anionic contaminants such as perfluorooctanoic acid and perfluorooctanesulfonic acid. Pearson correlation analysis established clear structure-performance relationships for the decrosslinking strategy. Natural water testing showed that NF-IPA@60 exhibit total organic carbon removal efficiencies exceeding 88.2 %, with 3.15-fold improvement in organic/mineral selectivity and excellent antifouling properties. This study provides a novel theoretical framework and technical approach for high-performance NFM design, offering significant potential for overcoming traditional membrane technology bottlenecks.

The sustainability and reliability of nanofiltration (NF) technology are critical for producing safe drinking water from increasingly polluted sources. Hence, we developed a high-performance NF membrane featuring an innovative meteor crater-like microstructure to overcome the trade-off between perm-selectivity and enhanced anti-fouling performance. Compared to conventional polyamide NF membranes characterized by nodular and striped structures, the NF membrane resembling a meteor crater exhibited looser structural configurations, larger water-surface areas, increased negative charge density, and enhanced hydrophilicity. The water permeance of the meteor crater-like microstructures improved by 2 similar to 4 times compared to conventional NF membranes, with excellent removal efficiency for Na2SO4 (> 98.5 %) and emerging foulants (> 91.3 %, especially bisphenol A rejection can reach 95.8 %). Furthermore, the meteor crater-like NF membranes mitigated the risk of mineral scaling due to the enhanced Donnan effect and separation selectivity. Moreover, computational fluid dynamics simulations revealed that meteor crater-like NF membranes exhibited higher shear stress distributions and greater inhomogeneity in the velocity field in the deposition direction. As a result, a dual resistance to both fouling and scaling was achieved. These advancements align NF membranes within the water-energy-environmental triad and paving the way for broader applications of NF technology in sustainable drinking water supply.