Humic acid (HA) extracted from digested sludge offers a sustainable precursor for energy-storage electrodes but is limited by low intrinsic conductivity. Here, a mild anti-solvent self-assembly strategy is proposed to construct HA/sulfonated polyaniline (HA/SPANI) nanocomposites with a stable conductive interface and hierarchical porous structure. Strong π-π interactions and hydrogen bonding between HA and SPANI effectively enhance electron/ion transport and structural stability. The optimized HA/SPANI nanocomposite exhibits a high specific capacitance of 797 F g-1 at 1 A g-1 with improved rate performance and cycling stability compared with pristine PANI. A flexible symmetric supercapacitor assembled from this material achieves an energy density of 12.7 Wh kg-1 at a power density of 200 W kg-1 and stable operation in powering multicolor LEDs. This work provides a sustainable route for the high-value utilization of digested sludge and demonstrates an eco-friendly pathway toward high-performance electrode materials for next-generation flexible energy storage devices.

Understanding bacterial transport and fate in porous media is critical for effective bioremediation and water quality management. Although bacteria mediate (trans)formation of diverse nanoparticles, how biomineralization affects cell mobility remains unclear. Here, association with different biogenic nanoparticles was found to enhance the transport of mineralized Shewanella oneidensis MR-1 cells in quartz sand columns by altering bacterial viability, surface potential or hydrophobicity. Moreover, silver nanoparticle (AgNPs) biomineralization augmented extracellular electron transfer, energy taxis and redox responsiveness of resultant AgNPs-mineralized cells but impeded their mobility in ferrihydrite- and birnessite-coated columns. While quinone electron shuttles increased cell deposition in mineral-coated columns by stimulating energy taxis, natural humic acids promoted cell breakthrough through electrosteric repulsion. Negative tactic response toward abiogenic AgNPs induced enhanced breakthrough and pronounced blocking effects in bare sand column. Concurrence of negative chemotaxis toward abiogenic AgNPs and positive energy taxis toward ferrihydrite facilitated the transport of pristine MR-1, but restrained that of AgNPs-mineralized cells. Enhanced AgNPs-mineralized cells retention in ferrihydrite-coated columns further enabled AgNPs immobilization via microbial transformation of ferrihydrite to magnetite. In contrast, cell-associated AgNPs retained in birnessite-coated columns could be remobilized as nanoparticles via bioreductive birnessite dissolution or as Ag+ via birnessite oxidation, increasing the risk of silver dissemination.

Nano-biochar (NBC) is recognized as an effective mediator for microbial extracellular electron transfer (EET). However, its specific role in regulating microbial energy taxis toward insoluble minerals and toxic soluble electron acceptors remains unexplored. In this study, it was demonstrated through swim plate and capillary assays that NBC effectively mediated the tactic response of Shewanella oneidensis MR-1 toward ferrihydrite (Fh) and hexavalent chromium (Cr(VI)). Among the tested variants, NBC pyrolyzed at 600 °C (NBC600) exhibited the optimal mediating efficacy. Its abundant redox-active quinone groups facilitated the bacterial energy taxis, expanding the migration area diameter (at 50 mg/L) by 1.3 to 1.6 times compared to other variants. Furthermore, for the soluble Cr(VI), energy taxis represented a dynamic metabolic trade-off. While 1.0 mg/L Cr(VI) suppressed migration by 75.3% compared to 0.1 mg/L due to cytotoxicity, NBC addition alleviated this stress primarily through physical sequestration. This intervention improved the energetic cost-benefit balance, restoring migration by 226.3% and boosting cellular ATP production by 25.7%. NBC therefore dynamically facilitates microbial energy taxis, offering a mechanism to support the survival of electroactive bacteria in contaminated environments.

Introduction Copper nanoparticles (Cu-NPs) have been increasingly released into marine environments due to their extensive applications, posing potential risks to marine organisms and human health. Although Cu-NPs of different particle sizes exhibit distinct toxicities-largely attributed to variations in specific surface area and Cu2+ dissolution rates-current physicochemical parameters still fail to fully explain these toxic effects, and the underlying molecular mechanisms remain unclear.Methods This study aimed to investigate the toxic effects and underlying molecular mechanisms of Cu-NPs of different nominal primary diameters (10 nm, 50 nm, and 100 nm) on the marine medaka (Oryzias melastigma).Results LC50 point estimates suggested slightly higher toxicity for smaller Cu-NPs. Integrated miRNAomic and transcriptomic analyses revealed that Cu-NPs-10 exposure markedly activated multiple metabolic pathways, including drug metabolism-cytochrome P450, retinol metabolism, and ascorbate and aldarate metabolism. Cu-NPs-50 exposure primarily affected neurodevelopment and synaptic signaling, with predicted miRNA-mRNA associations including miR-202 with mprip-like and miR-2187 with adgrg2-like. In contrast, Cu-NPs-100 exposure activated inflammation- and barrier repair-related networks, with potential miRNA-mRNA relationships involving miR-202 with tm4sf5, miR-106a, miR-132c, miR-200b, and miR-202 with znfx1, as well as miR-2187 and miR-202 with rhbdl2.Discussion Collectively, the integrated miRNA-mRNA analysis suggests that smaller Cu-NPs show a correlation with more intense molecular stress responses than larger particles under seawater transformations (e.g., aggregation/dissolution), and provides insights into the key regulatory networks potentially underlying these size-associated responses.

Passivation of metal catalysts hinders heterogeneous catalytic ozonation in degrading refractory organic pollutants (ROP). With strong electron interactions, polymetallic catalysts can enhance interfacial electromigration and regenerate active sites, improving ROP degradation. In this study, a Ni-Cu@Fe-Ceramsite catalyst was developed by co-doping nickel and copper onto Fe-ceramsite derived from sludge digestion residue, targeting ozonation of fiberboard wastewater. Morphological analysis showed nickel and copper uniformly distributed on the catalyst surface, increasing active sites while preserving porosity. Ni-Cu@Fe-Ceramsite achieved a 76.1 % removal of ROP at an initial CODcr concentration of 260 mg/L, representing a 14.6 % increase in ROP degradation efficiency and a 12 % improvement in ozone utilization compared to unmodified Fe-ceramsite. Additionally, it outperformed ozone alone by 33.6 % in degradation efficiency and 23 % in ozone utilization. The enhanced performance is attributed to the synergistic effects of nickel, copper, and iron, which boost metal reduction and the catalyst's electron-supplying ability, initiating reactions that decompose ozone molecules into reactive oxygen species such as center dot OH, center dot O2-, 1O2. This study underscores the potential of Ni-Cu@Fe-Ceramsite as an effective catalyst for wastewater treatment.

Electrochemical methods are promising for treating high-salt wastewater. However, their reliance on expensive membranes increases operational costs and introduces membrane-related challenges. To address this, our laboratory has developed a preparative vertical free-flow electrophoresis (PVFE) technique using cost-effective quartz sands instead of expensive membranes. This innovative technique has effectively produced acids and bases from industrial high-salt wastewater. However, a comprehensive understanding of the underlying mechanisms and mass transfer is essential to enhancing the design and performance of the developed PVFE. Herein, the effects of voltage, flow rate, and feed concentration on ion migration in PVFE were systematically examined, providing detailed insights into its driving mechanisms. Results revealed that quartz sand packing effectively suppresses ion diffusion while ensuring a proper ion orientation during electromigration and convection. Additionally, both simulation and empirical models validate the mass-transfer mechanisms and quantify the effect of key operational parameters on the ion transfer capacity. Economic analysis further highlights that PVFE operates within the limiting current, achieving ∼100% current efficiency at low operating costs (5.94 yuan/kg for base and 6.87 yuan/kg for acid). This study provides a comprehensive understanding of mass-transfer mechanisms in PVFE and offers valuable guidance for optimizing its practical application in high-salt wastewater recycling.

The inhibition of nitrite-oxidizing bacteria (NOB) has long been regarded as a major challenge for achieving stable partial nitrification (PN) process. However, the persistence of NOB, even under inhibitory conditions, suggests its potential functional importance in PN systems. This study comparatively analyzed the response of PN systems from reactor performance to gene expression, under ammonium and nitrite shock loadings to elucidate the hidden role of NOB. Results demonstrated that PN systems exhibited greater resistance to nitrite shock, maintaining a 58.2% ammonium removal efficiency even at a nitrite concentration of 300 mg L-1. But this resistance impaired when NOB activity was suppressed. Unlike elevated ammonium, high nitrite concentrations stimulated the expression of amo, hao, nirSK, norBC, and nosZ genes, enhanced ammonia monooxygenase and nitrite reductase activities, and improved the overall activity of ammonia-oxidizing bacteria (AOB). Isotopic analysis using 15N-labeled nitrite revealed the production of 30N and 29N, indicating that nitrite reduction mitigated nitrite toxicity to AOB. Notably, NO was identified as a potential signaling molecular mediating synergistic interactions between AOB and NOB, contributing to support system stability. Overall, this study provides unique insights into the functional role of NOB in improving the resilience and stability of PN systems under stress conditions.

Efficient utilization of digestate remains a key challenge in sustainable waste management. This study presents a green strategy by using humic acid (HA) extracted from digestate as a precursor for high-performance supercapacitor electrodes. Through K2CO3 activation, nitrogen doping, and copper incorporation, we synthesized Cu/N co-doped hierarchical porous carbon materials (CuNHAC) with strong metal-support interaction (SMSI). Structural characterization reveals the successful introduction of Cu-N/O coordination and enhanced surface functionality. Based on this microstructure, CuNHAC exhibits a high specific capacitance of 469 F g-1 at a current density of 0.5 A g-1, maintaining 98 % of its capacitance after 5000 charge-discharge cycles, demonstrating excellent cycling stability. First-principles calculations revealed that the SMSI effect promotes charge transfer and ion adsorption by modifying the carbon matrix's electronic structure. The CuNHAC-based supercapacitor device achieved an energy density of 15.7 Wh kg-1 at a power density of 250 W kg-1. Compared to other reported carbon-based materials, CuNHAC exhibited superior electrochemical performance, enhanced cycling life, and improved charge transfer efficiency. These results highlight the effectiveness of synergistic doping and interface engineering in boosting energy storage capabilities, while also offering a sustainable approach for utilizing digestate resources.

The ubiquitous occurrence of antibiotics in the environment induces various stress responses of microbes and increases the risk of the emergence and spread of antimicrobial resistance (AMR). In this study, the transport and retention of Shewanella oneidensis cells in saturated porous media was investigated under different levels of ciprofloxacin (CIP) stress. Exposing to lethal CIP stress caused significant viability loss and stimulated cell transport due to increasing hydrophilicity and decreasing surface roughness. While exposure to sublethal CIP stress did not affect MR-1's viability, elongation of cells promoted their retention in sand columns via straining and orientation effects. The elongated cells likely adopted an end-on configuration to minimize repulsive interaction energy when approaching sand surfaces and deposited in a side-on position due to local surface roughness and charge heterogeneity of sands. The more diminished breakthrough of MR-1 cells in redox-active media was ascribed to their improving extracellular electron transfer and energy taxis activities under sublethal CIP stress. Moreover, the retention of elongated cells in porous media facilitated the de novo emergence of a resistant gyrase mutant, whose remobilization might exacerbate the AMR dissemination.

The last two decades have seen nitrogen/iron-transforming bacteria at the forefront of new biogeochemical discoveries, such as anaerobic ammonium oxidation coupled to ferric iron reduction (feammox) and lithoautotrophic nitrate-reducing ferrous iron-oxidation (NRFeOx). These emerging findings continue to expand our knowledge of the nitrogen/iron cycle in nature and also highlight the need to re-understand the functional traits of the microorganisms involved. Here, as a proof-of-principle, we report compelling evidence for the capability of an NRFeOx enrichment culture to catalyze the feammox process. Our results demonstrate that the NRFeOx culture predominantly oxidizes NH4+ to nitrogen gas, by reducing both chelated nitrilotriacetic acid (NTA)-Fe(III) and poorly soluble Fe(III)-bearing minerals (gamma-FeOOH) at pH 4.0 and 8.0, respectively. In the NRFeOx culture, Fe(II)-oxidizing bacteria of Rhodanobacter and Fe(III)-reducing bacteria of unclassified_Acidobacteriota coexisted. Their relative abundances were dynamically regulated by the supplemented iron sources. Metagenomic analysis revealed that the NRFeOx culture contained a complete set of denitrifying genes along with hao genes for ammonium oxidation. Additionally, numerous genes encoding extracellular electron transport-associated proteins or their homologs were identified, which facilitated the reduction of extracellular iron by this culture. More broadly, this work lightens the unexplored potential of specific microbial groups in driving nitrogen transformation through multiple pathways and highlights the essential role of microbial iron metabolism in the integral biogeochemical nitrogen cycle.

Incubation of iron-reducing bacteria with Fe(III) could generate center dot OH to decompose organic pollutants under redox fluctuation conditions. However, the Fe(III)/Fe(II) transformation efficiency and therefore yields of center dot OH production in systems using Fe(III)-bearing minerals as respiration substrate of bacteria is unsatisfying. Here, we showed that different iron- and iron-copper-based metal-organic frameworks (Fe-MOFs and FeCu-MOFs) can mediate electron transfer from Shewanella oneidensis MR-1 to O2 through their Fe(III)/Fe(II) cycling during anoxic-oxic transition, resulting in generation of reactive oxygen species including center dot O2-, H2O2 and center dot OH. While 3 g/L of MIL-101(Fe) demonstrated faster Fe(III)/Fe(II) cycling, better yields of center dot OH production (69.0 mu mol/mmol Fe(II) oxidation) and sulfanilamide removal (81.5 % in 24 h) than iron-bearing minerals and the rest two FeMOFs (MIL-53(Fe) and MIL-88B(Fe)), Fe0.75Cu0.25-B surpassed the performance of MIL-101(Fe) and other FeCu-MOFs with different Fe/Cu ratios, which might be attributed to its larger surface area, higher amounts of associated Fe(II), and synergistic effects between Fe and Cu species. Moreover, both MIL-101(Fe) and Fe0.75Cu0.25-B maintained structure stability and persistent catalytic activity during four continuous redox cycles in 48 h, the center dot OH production and sulfanilamide degradation of which exceeded those of one-time operation in the same duration. This study revealed the efficacy of combining bacteria and MOFs for center dot OH production, and provided promising alternatives for oxidative degradation of contaminants.

Groundwater contamination with arsenic and nitrate poses a pressing concern for the safety of local communities. Bioremediation, utilizing Fe(II)-oxidizing nitrate reducing bacteria, shows promise as a solution to this problem. However, the relatively weak environmental adaptability of a single bacterium hampers practical application. Therefore, this study explored the feasibility and characteristics of a mixed iron-dependent autotrophic denitrifying (IDAD) culture for effectively removing arsenic and nitrate from synthetic groundwater. The IDAD biosystem exhibited stable performace and arsenic resistance, even at a high As(III) concentration of 800 μg/L. Although the nitrogen removal efficiency of the IDAD biosystem decreased from 71.4% to 64.7% in this case, the arsenic concentration in the effluent remained below the standard (10 μg/L) set by WHO. The crystallinity of the lepidocrocite produced by the IDAD culture decreased with increasing arsenic concentration, but the relative abundance of the key iron-oxidizing bacteria norank_f_Gallionellaceae in the culture showed an opposite trend. Metagenomic analysis revealed that the IDAD culture possess arsenic detoxification pathways, including redox, methylation, and efflux of arsenic, which enable it to mitigate the adverse impact of arsenic stress. This study provides theoretical understanding and technical support for the remediation of arsenic and nitrate-contaminated groundwater using the IDAD culture.

Anammox is recognized as a prospective alternative for future biological nitrogen removal technologies. However, the nitrate by-products produced by anammox bacteria limit its overall nitrogen removal efficiency below 88 %. This study introduced Fe(III) into the anammox bioreactor to enhance the nitrogen removal efficiency to approximately 95 %, surpassing the biochemical limit of 88 % imposed by anammox stoichiometry. Anammox sludge was demonstrated to utilize extracellular polymeric substances to reduce Fe(III) into Fe(II), and this process promoted the dominance of Ca. Brocadia. The iron addition improved the abundance of narGHI genes and facilitated the partial dissimilatory nitrate reduction to ammonium, with nitrite as the end product. The accumulated nitrite was then eliminated through the anammox pathway, along with the excess ammonium (30 mg/L) in the influent. Overall, this study deepens our understanding of the enhanced nitrogen removal triggered by Fe(III) in anammox sludge and offers an effective approach to boost anammox process.

Phosphogypsum has been a longstanding issue that poses environmental risks and economic pressure on society. Realizing the recycling of this waste is essential for achieving sustainable phosphorus chemical industry. In order to tackle this problem, this study examined the potential of using a preparative vertical-flow electrophoresis (PVFE) system with supporting media to recover calcium and sulphur from phosphogypsum without producing any by-products. NaOH was used to convert phosphogypsum into slaked lime and Na2SO4, with a maximum leaching efficiency of 98.6 % achieved at a NaOH concentration of 2 mol/L and a molar ratio of sodium to sulfur of 2.1. The slaked lime obtained met the quality standards outlined in the Chinese national standard (HG/T 4120-2009). Electrophoresis separation of the resulting Na2SO4 demonstrated that the NaOH effluent output could reach the desired concentration for reusing in the treatment of phosphogypsum. The addition of a solid supporting media (quartz sands) is the key to achieving the separation of Na2SO4. After considering the economic benefits, the optimal electrophoresis conditions for separating Na2SO4 were determined to be a supply voltage of 10 V and HRT of 240 min. These findings offer a directed and practical solution for the economical and effective recycling of phosphogypsum in phosphorus chemical industry.

Electrochemical desalination is an effective method for recovering salts from reverse osmosis (RO) brine. However, traditional technologies like bipolar membrane technology often face challenges related to membrane blockage. To overcome this issue, a preparative vertical-flow electrophoresis (PVFE) system was used for the first time to treat RO brine of petrochemical wastewater. In order to optimize the PVFE operation and maximize acids and bases production while minimizing energy consumption, the response surface method was employed. The independent variables selected were the electric field intensity (E) and flow rate (v), while the dependent variables were the acid–base concentration and energy consumption (EC) for acid–base production. Using the central composite design methodology, the operation parameters were optimized to be E = 154.311 V/m and v = 0.83 mL/min. Under these conditions, the base concentrations of the produced bases and acids reached 3183.06 and 2231.63 mg/L, respectively. The corresponding base EC and acid EC were calculated to be 12.57 and 11.62 kW·h/kg. In terms of the acid–base concentration and energy consumption during the PVFE process, the electric field intensity was found to have a greater influence than the flow rate. These findings provide a practical and targeted solution for recycling waste salt resources from RO brine.

Anthropogenic stresses are intensively affecting the structure and function of microbial communities in coastal ecosystems. Despite being essential components of coastal ecosystems, the environmental influences and assembly processes of protist communities remain largely unknown in areas with severe disturbance. Here, we used 18S rRNA gene high-throughput sequencing to compare the composition, assembly process, and functional structure of the protist communities from the coastal areas of the Northern Yellow Sea (NYS) and the Eastern Bohai Sea (EBS). These two areas are separated by the Liaodong Peninsula and experience different anthropogenic stresses due to varying degrees of urbanization. We detected significant differences between the protist communities of the two areas. Environmental and geographic factors both influenced the composition of protist communities, with environmental factors playing a greater role. The neutral community model indicated that the assembly of protist communities was governed by deterministic processes, with stochastic processes having a stronger influence in the EBS area compared to the NYS area. The phototrophic and consumer communities, influenced by different environmental factors, differed significantly between the two areas. Our results provide insights into the biogeography and assembly of protist communities in estuaries under anthropogenic stresses, which may inform future coastal management.

The biogeochemical cycling of iron is crucial to plenty of environmental processes, and is often influenced by black carbon with high electrical conductivity and abundant functional groups. This study for the first time revealed that diesel particulate matter (DPM), a typical black carbon material which often caused serious environmental effects, could significantly promote dissimilatory reduction of both abiogenic and biogenic goethite (CGt and BGt) by Shewanella oneidensis MR-1. In 7 days, Fe(II) production in CGt systems containing 0.5, 5, 10, 25, and 50 mg/L of DPM were 1.2, 1.3, 1.8, 1.9, and 2.7 folds higher than that in the system without DPM (0.12 mM), respectively. During the bioreduction of BGt, Fe(II) concentrations were 2.4-3.4 folds higher than those in the CGt systems, and were increased by 4.8%- 41.7% with the addition of 0.5-50 mg/L DPM. X-ray diffraction (XRD) analysis demonstrated that goethite was the sole mineralized product during the bioreduction of CGt, while vivianite appeared gradually during the microbial transformation of BGt. DPM enhanced electron transfer between cells and goethite via serving as electron shuttles. The results of this study would improve our understanding of interactions among microbes, natural minerals, and black carbon in the natural environments.

Anaerobic digestion is an environmentally friendly method for reclaiming waste activated sludge. However, it cannot be overlooked that the solid residue generated from this process can still pose environmental risks and impose economic pressure on society. To mitigate and recycle the solid residue, this study utilized it as a primary raw material for manufacturing ceramsite with potential applications in wastewater treatment. The optimal ratio of solid residue to fly ash was demonstrated to be 6:4 with an additional 15% of clay supplementing the raw ceramsite materials. Furthermore, the optimal sintering process was established as preheating at 300 °C for 25 min followed by sintering at 1085 °C for 10 min, as determined through an L16 (44) Orthogonal test. The prepared ceramsite demonstrated advantageous performance parameters that exceeded the standards outlined in the Chinese industry standard CJ/T 299-2008 for water treatment artificial ceramsite. When utilized in an ozonation system, the ceramsite exhibited remarkable catalytic activity for phenol degradation by promoting the decomposition of molecular O3 into hydroxyl radicals. Additionally, it displayed minimal leaching of heavy metals and lower application costs. These findings emphasize its attractiveness in water and wastewater treatment processes and present a practical strategy for reclaiming this solid residue.

针对污泥沼渣中有机质难以回收利用的问题,利用热碱法破解污泥沼渣,探究了不同条件对沼渣破解率和有机物溶出率的影响,确定了热碱法处理污泥沼渣的最佳条件为:pH=13、T=80 ℃、t=8 h.此条件下,污泥沼渣的破解率为40.9％,COD、蛋白质、多糖的溶出率分别为722.2,79.7,73.7 mg/g VSS.利用热碱处理后的污泥沼渣破解液进行厌氧发酵产甲烷,比较了不同初始pH值对厌氧发酵的影响,发现初始pH值的改变对有机物降解率的影响较小,但初始pH值的增加会提高发酵过程中CH4的产率,降低CO2的产率,提高产气中CH4含量.因此确定初始pH值=13时污泥沼渣破解液产甲烷效果最好,此时COD去除率为61.1％,CH4产率达到65.0 mL/g VSS,产气中CH4含量能够达到81.0％.该研究证明热碱处理可提高污泥沼渣的可生化性,具有应用于厌氧发酵产甲烷的潜力.

Aromatic azo dyes possess inherent resistance and are known to be carcinogenic, posing a significant threat to human and ecosystems. Enhancing the biodegradation of azo dyes usually requires the presence of co-metabolic substrates to optimize the process. In addressing the issue of excessive waste activated sludge (WAS) generation, this study explored the potential of utilizing alkaline-thermal hydrolysate of WAS as a co-metabolic substrate to boost the degradation of reactive black 5 (RB5) dyes. The acclimated microbial consortium, when supplemented with the WAS hydrolysate obtained at a hydrolysis temperature of 30 °C, achieved an impressive RB5 decolorization efficiency of 90.3% (pH = 7, 35 °C) with a corresponding COD removal efficiency of 45.0%. The addition of WAS hydrolysate as a co-substrate conferred the consortium with a remarkable tolerance to high dye concentration (1500 mg/L RB5) and salinity levels (4-5%), surpassing the performance of conventional co-metabolic sugars in RB5 degradation. 3D-EEM analysis revealed that protein-like substances rich in tyrosine and tryptophan, present in the WAS hydrolysate, played a crucial role in promoting RB5 biodegradation. Furthermore, the microbial consortium community exhibited an enrichment of dye-degrading species, including Acidovorax, Bordetella, Kerstersia, and Brevundimonas, which dominated the community. Notably, functional genes associated with dye degradation and intermediates were also enriched during the RB5 decolorization and biodegradation process. These findings present a practical strategy for the simultaneous treatment of dye-containing wastewater and recycling of WAS.