Efficient nitrogen removal from aquaculture wastewater is critical for sustaining aquatic ecosystem sustainability. In this study, a highly efficient heterotrophic nitrification-aerobic denitrification (HN-AD) bacterium was isolated from aquaculture sediment. The strain was identified as Pseudomonas fluorescens JSRD-3 and evaluated for its nitrogen removal performance. Sodium citrate was determined as the optimal carbon source. Strain JSRD-3 exhibited excellent nitrogen removal across wide ranges of C/N ratio, pH, dissolved oxygen (DO), temperature, and salinity. With single nitrogen sources, complete removal of ammonium (NH4[+]-N), nitrate (NO3[-]-N), and nitrite (NO2[-]-N) was achieved within 12 h. Mixed nitrogen experiments further confirmed that strain JSRD-3 could simultaneously and efficiently transform multiple inorganic nitrogen species. It showed a significant preference for NH4[+]-N utilization. Response surface methodology (RSM) identified pH, temperature, and shaking speed as the key influencing factors. Under the optimized conditions, NH4[+]-N removal reached 98.90% at 9 h. Microbial immobilization further enhanced the NO3[-]-N removal efficiency and operational stability of the strain. Polyurethane foam immobilization outperformed loofah sponge. Notably, polyurethane foam-immobilized JSRD-3 completely removed NH4[+]-N, NO2[-]-N, and NO3[-]-N from real non-sterile aquaculture wastewater within 16 h. These results highlight JSRD-3 as a promising candidate for rapid, efficient, and interference-resistant nitrogen removal in practical aquaculture wastewater treatment.

This study assessed the feasibility and environmental implications of utilizing pig and cattle manure as solid fuels, with a focus on flue-gas emissions and ash recyclability. Cattle manure - derived solid fuel, produced by reducing moisture content to approximately 4%, achieved a lower heating value (LHV) of 14.6 MJ kg[-][1] and an ash content of 21.5%, meeting Republic of Korea solid-fuel quality standards (LHV ≥ 12.6 MJ kg[-][1], ash ≤ 30%, moisture < 20%). In contrast, pig manure - derived solid fuel exhibited a moisture content (12.5%) that satisfied the standard, but a lower LHV (8.5 MJ kg[-][1]) and higher ash content (34.6%), failing to meet fuel quality criteria. Stack measurements revealed distinct emission characteristics. For cattle manure, selective non-catalytic reduction (SNCR) enabled stable emission control, with dust (1.3 mg m[-][3]), CO (105.7 ppm), NOx (46.8 ppm), and SOx (17.2 ppm) within regulatory limits. Conversely, pig manure combustion produced excessive SOx emissions (286 ppm vs. 60 ppm limit) even with SNCR, indicating need for additional desulfurization or alternative utilization pathways. Residue analysis showed that over 90% of ash was recovered as bottom ash, with phosphorus concentrated in this fraction, indicating reuse potential. However, pig manure ash contained elevated Cu and Zn levels, exceeding fertilizer standards and requiring stabilization before recycling. Overall, cattle manure demonstrated favorable environmental performance, whereas pig manure posed challenges related to sulfur-related air pollution and heavy-metal enrichment. These results highlight the need to jointly consider environmental risk management and resource recovery when promoting livestock manure as a renewable energy source.

Hydroxyl radicals (•OH) dominate atmospheric oxidation chemistry, yet their controlled and reproducible generation in laboratory systems remains technically challenging. In this work, a gas-phase UV/H2O2-based Hydroxyl Radical Generation System (HyRaG) was developed and experimentally optimized to provide stable and tunable •OH production under precisely regulated thermal and flow conditions. The HyRaG integrates three functional modules: a quartz double-cylinder photolysis reactor, a closed-loop dual-channel temperature control unit capable of maintaining outlet temperature variations within ±1°C during continuous operation, and a mass-flow-regulated N2/H2O2 vapor delivery system. An outlet-based sulfur dioxide (SO2) decay method was employed to quantify •OH generation under carrier gas flow rates of 10-300 mL min[-1] and temperature of 15-50°C, yielding •OH concentrations ranging from 0.41-2.04 × 10[11] molec.cm[-3]. Single-factor experiments revealed parabolic dependences of •OH generation on both operational parameters, with optimal conditions near 100 mL min[-1] and 40°C. Further optimization using Response Surface Methodology (RSM) based on a Central Composite Design (CCD) produced a robust second-order predictive model (R[2] = 0.9735), demonstrating significant quadratic effects of both temperature and carrier gas flow rate, while their interaction was statistically insignificant. By decoupling radical generation from the reaction environment and stabilizing thermal conditions, HyRaG enables a controllable and reproducible oxidizing environment for atmospheric simulation studies and provides a scalable platform for mechanistic investigations of radical-driven gas-phase chemistry.

This study addresses the pollution challenges posed by fluoride-containing wastewater in the photovoltaic industry and explores the potential for fluorine resource recovery. It proposes a seed-induced electrocoagulation-crystallization (EC-C) strategy to achieve efficient fluoride removal and high-value recovery of cryolite (Na3AlF6). The key operating parameters for electrocoagulation (EC) were systematically optimized, with optimal conditions determined as: electrode area of 150 cm[2], electrode spacing of 1.2 cm, 0.05 M NaCl + NaHCO3 composite electrolyte, and initial fluoride concentration of 3000 mg/L. Under these conditions, fluoride removal efficiency reached 94.4% with minimal energy consumption and anode loss, conforming to pseudo-first-order kinetics. To regulate crystallization pathways and product quality, seed-assisted crystallization was introduced: Commercial Na3AlF6 seed crystals (CNSC) outperformed Autocatalysed seeds crystals (ASC), with an optimal dosage of 0.75 g administered via stepwise addition over 0-20 min, significantly enhancing product phase content. This yielded high-content cryolite with 97.5% content. FTIR/XRD analysis revealed that fluorinated aluminum intermediates undergo progressive dehydration and transformation into a cryolite crystal phase dominated by Al-F bonds. This study established an integrated pathway for efficient fluoride removal and high-value recovery through coupled regulation of parameter windows and seeding timing, providing theoretical and process foundations for the high-value utilization of fluorinated photovoltaic wastewater.

The development of efficient low-phosphorus water treatment formulations is essential for sustainable industrial water management. In this study, a novel quadri-component corrosion and scale inhibitor PPHZ was developed by rationally combining biodegradable polyaspartic acid (PASP), phosphonobutane-tricarboxylic acid (PBTCA), hydrolyzed polymaleic anhydride (HPMA), and ZnCl2. The formulation exhibits excellent dual-functional performance in both scale and corrosion inhibition. At a dosage of 50 mg/L, PPHZ achieves 95% CaCO3 scale inhibition by effectively distorting crystal growth and completely transforming calcite/aragonite into non-adherent vaterite. Notably, only 10 mg/L of PPHZ is sufficient to completely inhibit CaSO4 scale formation. In simulated circulating water, PPHZ achieves a corrosion inhibition efficiency of 90% for carbon steel at 30 mg/L. Electrochemical analysis reveals that PPHZ simultaneously suppresses both anodic and cathodic reactions through a 'Zn[2+]-bridging' hybrid film mechanism, while surface characterization (SEM-EDS, XRD) confirms the formation of a dense hybrid protective film. The formulation has a theoretical phosphorus content of only 2.296%, achieving >92% phosphorus reduction compared to conventional phosphorus-based agents, in line with the sustainable development trend of water treatment technologies. PPHZ provides an effective strategy for integrated corrosion and scale control in industrial water systems.

Perfluorooctanoic acid (PFOA), remains a major environmental challenge due to its exceptional chemical stability, resistance to conventional treatment technologies. In this study, a sustainable carboxymethyl cellulose-reinforced graphene oxide/molybdenum disulfide hydrogel (MoS2/GO/CMC) was developed as a visible-light-responsive photocatalyst for PFOA degradation under low-power LED irradiation. The photocatalytic process was optimized using Response Surface Methodology based on a Box-Behnken Design, evaluating the effects of irradiation power (7-12 W), catalyst dosage (0-0.04 g), and initial PFOA concentration (10-50 mg L[-][1]). The optimized conditions (12 W, 0.04 g catalyst, and 30 mg L[-][1] PFOA) achieved 99.8% degradation efficiency, with the developed quadratic model exhibiting excellent predictive capability (R[2] = 0.9974). Characterization results confirmed integration of MoS2 and GO within the CMC matrix, producing a heterostructure with a narrow band gap of 1.12 eV, enhanced charge separation, and suppressed electron-hole recombination. Kinetic analysis revealed pseudo-first-order degradation behaviour with a rate constant of 0.013 min[-][1] and a half-life of 0.89 h. Radical scavenging experiments identified superoxide radicals (O2•[-]) as the dominant reactive species governing PFOA degradation. LC-MS analysis confirmed a stepwise chain-shortening degradation pathway involving intermediates such as PFHpA, PFPeA, and PFBA, indicating progressive defluorination and carbon-carbon bond cleavage. The hydrogel demonstrated excellent stability, retaining over 96% of its initial activity after seven cycles. An Electrical Energy per Order (EEO) value of 444.6 kWh m[-][3] order[-][1] highlights the feasibility of low-energy operation. These findings demonstrate that MoS2/GO/CMC hydrogels offer an environmentally benign, recoverable, and energy-efficient for PFAS remediation.

Bioelectrochemical systems offer a promising approach for nitrogen polishing of low-strength, carbon-limited wastewater; however, how electron-acceptor availability governs nitrogen conversion and electrochemical behaviour remains unclear. In this study, a bioelectrochemical sequencing batch reactor (BeSBR) and a control reactor were operated in sequencing batch mode, in which electron-acceptor conditions were sequentially varied within the same reactor system. The reactors were subjected to nitrite-abundant, nitrite-limited, nitrite-free, and oxygen-exposed phases, each maintained until stable performance was achieved. Nitrogen conversion was evaluated using cycle-based concentration profiles under steady-state conditions. Stable nitrogen polishing was achieved without external organic carbon addition, and powdered activated carbon (PAC) served as a conductive mediator supporting microbial retention and extracellular electron transfer. Nitrite-abundant conditions exhibited the most favourable electrochemical characteristics, while ammonium removal persisted under nitrite-limited and nitrite-free conditions, indicating adaptive nitrogen conversion under alternative electron acceptors. Kinetic analysis showed that ammonium removal exhibited approximately linear, zero-order-like behaviour under most conditions, with rates in the range of 2.0-2.5 mg N L[-1] h[-1], corresponding to removal of ∼25 mg N L[-1] within 10-12 h. Biomass stabilised at approximately 3,000-3,500 mg/L after initial reduction, indicating microbial adaptation. Microbial and functional analyses suggested multiple coexisting pathways, including nitrite-associated processes, dissimilatory nitrate reduction to ammonium, and sulfur-linked reactions. Overall, nitrogen conversion was governed by dynamic redox reconfiguration driven by electron-acceptor availability, rather than a single dominant pathway, highlighting its potential as an energy-efficient nitrogen polishing strategy.

The contamination of wastewater by antibiotics poses significant ecological risks. Here, a novel Fe-Mn co-doped nitrogen-doped biochar (Fe-Mn@NBC) was synthesized from corn straw via impregnation-chelation-pyrolysis to activate periodate (PI) for oxytetracycline (OTC) degradation. The Fe-Mn@NBC/PI system demonstrated outstanding degradation performance, achieving an OTC removal rate of 96.2% within 90 min, with a reaction constant of 0.237 min-1. The unit degradation efficiency of OTC for Fe-Mn@NBC/PI system was calculated to be 320.7 mg·(g·mmol)-1, outperforming many similar catalysts reported in the literature. This enhanced performance is attributed to the porous structure, large surface area, and abundant active sites of Fe-Mn@NBC, which optimize charge distribution and facilitate electron transfer. The system maintained good degradability and reusability under various hydraulic conditions (pH, inorganic anions, humic acid, actual water). Mechanistic studies revealed that 1O2, O2•-, and IO3• were the dominant reactive species. Using HPLC-MS and Fukui function analysis, electron-rich groups (-CONH2, -COOH) were identified as primary attack sites, leading to three proposed OTC degradation pathways, with key intermediates showing low toxicity via T.E.S.T. analysis. This study not only presents a sustainable approach for repurposing waste corn stalk biomass but also offers a cost-effective and eco-friendly solution to combat antibiotic pollution in wastewater.

Efficient regeneration of spent activated carbon (SAC) is critical for sustainable VOC abatement, yet the multiscale structural evolution during thermal treatment remains poorly understood. This study elucidates the multiscale structural evolution mechanism of SAC during thermal regeneration - from contaminant desorption to carbon matrix reorganization - through integrated multi-technique characterization (BET, SEM, TGA, XRD, FTIR). Key findings reveal a three-stage 'cleaning-reconstruction-degradation' mechanism: (i) Low-temperature treatment (300-400°C) removes surface contaminants and oxygen-containing groups, reopening blocked micropores; (ii) Optimal treatment at 400-500°C for 1-2 h achieves near-complete contaminant removal (>95%) while inducing controlled graphitization and beneficial mesoporosity development, restoring SBET to 965-1020 m[2]/g with well-preserved microporous architecture, indicating high potential for adsorption capacity recovery; (iii) Excessive treatment (≥600°C for 3 h) causes micropore collapse and sintering, reducing surface area. These findings establish a scientifically grounded optimal regeneration window (400-500°C, 1-2 h) that balances contaminant desorption efficiency with carbon matrix preservation, offering practical guidance for energy-efficient industrial regeneration of VOC-laden activated carbon from organic chemical manufacturing processes.

Rapid population growth has intensified pressure on freshwater (FW) resources, significantly impacting agricultural practices and worsening food scarcity in many regions. The reuse of treated wastewater (TWW) for irrigation addresses water scarcity but carries the risk of spreading pathogenic microbes and antibiotic-resistant bacteria (ARB). Free-living amoebae (FLA) in soil prey on bacteria and have been proposed as biocontrol agents. Here, we suggest an eco-biological approach, investigating how key ions in TWW (phosphate, ammonium, and sulphate) affect predation by three FLA species (Vermamoeba vermiformis, Acanthamoeba castellanii and Heterolobosea sp.) on model bacterial prey GFP-tagged Escherichia coli and GFP-tagged Enterococcus mundtii. This approach aims to enhance soil microbial safety and reduce pathogen persistence in irrigation systems. We also develop a YOLOv5 deep-learning model to quantitatively track FLA behaviour in microscopy videos. Our results show that PO43- or NH₄⁺ (100 mg/L) enrichment greatly enhances Vermamoeba's grazing on E. coli (7 log10 reductions in 72 h) compared to controls or SO₄²- addition. Fluorescence microscopy images confirm extensive bacterial interaction and killing by Vermamoeba in PO43- and NH₄⁺ enrichment. In contrast, Acanthamoeba and Heterolobosea had weaker effects. A mixed FLA consortium, however, eliminated E. mundtii faster than any single FLA species. The YOLOv5 model trained on an annotated dataset and validated against manual viable-cell counts reliably tracked FLA movement. These findings suggest that tailoring nutrient levels in TWW can enhance the biocontrol function of FLAs. Our interdisciplinary approach lays groundwork for ecological and AI-informed strategies to make TWW reuse safer.

With the acceleration of global industrialization, the environmental risks posed by heavy metals in sludge have become increasingly prominent. Traditional treatment methods struggle to effectively reduce the bioavailability of these metals, whereas pyrolysis facilitates the fixation and transformation of heavy metals via high-temperature conversion. This study investigated the migration and transformation of heavy metals during sludge pyrolysis, focusing on the influence of pyrolysis temperature and heating rate on the distribution and morphology of these metals. The results revealed that both the pyrolysis temperature and heating rate significantly affected the fixation efficiency, migration behavior, and chemical form of the heavy metals. Pyrolysis temperature and heating rate significantly affect heavy metal behavior. Optimal stabilization is achieved at 700 and 10 °C min-1, which drastically reduces the potential ecological risk index (RI) from 156.97 to 9.83 and 10.80. These conditions facilitate metal migration into gas/liquid phases and convert active fractions (F1/F2) into the stable residual fraction (F4). The crystal structure and functional group changes of the pyrolysis products were further analyzed by X-ray diffraction and infrared spectroscopy. The results show that the higher pyrolysis temperature will weaken the characteristic peak intensity of SiO2. The faster heating rate will enhance the crystallization of graphite carbon and accelerate the dehydration/alkane decomposition reaction, which can be confirmed by the weakening of -OH and -CH stretching vibration intensity. This study provides a theoretical foundation for optimizing the sludge pyrolysis process and contributes to the realization of resource utilization in sludge treatment.

Anaerobic processes are widely applied for the treatment of agro-industrial wastes, enabling both pollution control and resource recovery through energy production. Among agro-industries, bulgur-producing wheat processing facilities generate wastewater rich in rapidly hydrolysable biodegradable organic matter. In this study, the anaerobic treatment of bulgur processing wastewater was investigated under batch mesophilic conditions, with a focus on energy and resource recovery supported by kinetic modelling. The process achieved more than 95% total COD (tCOD) removal, confirming the high biodegradability of the wastewater. Cumulative biogas production reached approximately 0.22 m3/kg tCODfed, with a methane yield of 0.13 m3 CH₄/kg tCODfed. Process progression was governed by rapid acidification during the early stages of treatment, followed by system recovery and stabilization. Volatile fatty acid (VFA) production peaked within the first days of operation, with a dominant acid sequence of butyric > acetic > propionic acids. The substantial VFA production further highlights the potential of bulgur wastewater for dual resource recovery, supporting both biogas generation and polyhydroxyalkanoate (PHA) production within a biorefinery framework. Methane production kinetics were successfully described using the Modified Gompertz model, which showed excellent agreement with experimental data and provided quantitative insight into methane production potential, lag phase duration, and maximum methane production rate. Overall, the integration of experimental results with kinetic modelling demonstrated that bulgur processing wastewater can be effectively managed through anaerobic treatment while serving as a flexible platform for both biogas generation and PHA production.

Sewage sludge often contains heavy metals and antibiotic resistance genes (ARGs), posing challenges for its safe disposal. Bioleaching is a promising technique for heavy metal removal, but its impact on antibiotic resistance genes (ARGs), particularly when mediated by diverse consortia, remains unclear. This study systematically compared the efficiency of different functional microbial consortia, including Acidithiobacillus ferrooxidans (A. ferrooxidans), Acidithiobacillus thiooxidans (A. thiooxidans), and their combinations with the acid-tolerant yeast Rhodotorula mucilaginosa (R. mucilaginosa), for simultaneous bioleaching of heavy metals and removal of ARGs from sewage sludge. Results showed that the tripartite consortium (A. ferrooxidans + A. thiooxidans + R. mucilaginosa) achieved the highest removal efficiencies for copper (85.77%), arsenic (77.19%), and lead (70.88%). ARGs abundance generally decreased after bioleaching, with consortia containing A. ferrooxidans being most effective. A significant positive correlation was found between the reduction in Proteobacteria and the decrease in multiple ARGs. Interestingly, positive correlations were also observed between several heavy metals (Cr, Cu, Ni, As, Zn) and specific ARGs (IreK, macB, mlaF), indicating a complex interplay. This study highlights the importance of microbial synergy and heavy metal speciation in the co-control of heavy metals and ARGs in sewage sludge, providing insights for developing strategies for harmless treatment of sludge.

Atmospheric pollution remains a major concern for public health and city sustainability, especially in densely populated metropolitan regions with complex environmental dynamics. Traditional prediction techniques often rely on static feature selection methods that disregard the spatial and temporal variations embedded in pollutant behaviour. In this work, we introduce FAST (Feature-Adaptive Selection and Transformation), a novel approach for dynamic feature selection for spatiotemporal air quality forecasting. FAST applies attention-based methods to dynamically update relevant features based on spatial and meteorological conditions at any given time while improving interpretability and predictive performance. We evaluate FAST over three of the largest Indian metropolitan areas, Delhi, Mumbai, and Bengaluru, based on real-world air quality measurements from 90 + monitoring stations. The system is benchmarked against conventional filter, wrapper, and embedded feature selection techniques and demonstrates consistent improvements in forecasting accuracy, with up to 18% lower Mean Absolute Error (MAE) and up to 12% improvement in R[2] values. FAST demonstrates consistent performance across the evaluated 6-hour and 48-hour forecasting horizons while also providing interpretable insights into seasonal and spatial patterns of pollution. By dynamically adapting to the evolving nature of urban air quality, FAST provides an approach for data-driven air quality forecasting in urban environments.

The accumulation of inorganic nitrogen in intensive aquaculture systems necessitates treatment strategies that combine rapid conversion kinetics with operational robustness. In this study, Pseudomonas putida 4-HYK was isolated and systematically evaluated for inorganic nitrogen removal under both synthetic media and real aquaculture wastewater conditions. Batch experiments demonstrated complete removal of ammonium, nitrite, and nitrate (20 mg L-1) within 15, 18, and 21 h, respectively, with maximum removal rates reaching 1.67, 1.33, and 1.04 mg L-1 h-1 and no detectable accumulation of intermediate nitrogen species. Under mixed-nitrogen conditions, the strain exhibited a consistent sequential utilisation pattern, preferentially assimilating ammonium prior to nitrite and nitrate reduction. Stable nitrogen removal was maintained across a broad operational window (C/N ratio 3-20, pH 7-9, and 25-35 °C), while measurable activity persisted at pH 4 and salinity up to 40‰, indicating strong environmental tolerance relevant to aquaculture settings. Dissolved oxygen availability was identified as a critical factor for achieving complete nitrogen removal. Process validation using real industrial aquaculture wastewater (NH₄⁺-N 8.36 mg L-1; NO₂--N 5.12 mg L-1; NO₃--N 2.85 mg L-1) showed that complete inorganic nitrogen removal could be achieved within 24 h at inoculation levels of 0.5-2% when brown sugar was applied as an economical external carbon source, supporting the technical feasibility of low-cost biological treatment. These results demonstrate that 4-HYK enables rapid and complete nitrogen removal with strong tolerance to variable environmental conditions, providing a practical biological option for nitrogen control in aquaculture wastewater treatment systems.