Aerobic granular sludge (AGS) is a self-aggregated three-dimensional microbial aggregate and has great potential for treating high salinity wastewater, but quantitative, non-destructive analysis of its internal structure is limited. This study employed novel high-resolution micro-computed tomography (Micro-CT) to non-destructively quantify the internal structural response of AGS under salinity. Results showed that increasing salinity from 0 % to 5 % raised AGS porosity from 57 % to 72 %. The total pore count decreased markedly while average pore size increased from 76.02 μm to 157.64 μm. Conversely, biomass aggregate size declined significantly with increasing salinity. The increased porosity and reduced biomass demonstrated that salinity ≤2.5 % preserved structural integrity while salinities above 3.5 % led to notable internal damage. The robust internal structure at moderate salinity (≤2.5 %) created a microenvironment that stimulated the secretion of protective EPS, which in turn reinforced the structure by fostering dense internal biomass aggregates. Based on the internal structure and composition, the average particle size decreased from 2855.13 μm at 1 % salinity to 1186.78 μm at 5 % salinity, indicating granulation reduction. The internal structure of the granules directly dictated operational stability. Although all reactors removed pollutants effectively, the severe structural collapse at high salinity (≥3.5 %) caused prolonged recovery periods and greater fluctuations in removal efficiency, signifying a profound loss of functional resilience. By providing a non-destructive method for internal analysis, this work elucidated that internal structural failure preceded macroscopic collapse and was a key determinant of AGS instability in hypersaline environments, offering crucial insights for the robust design and operation of AGS systems for industrial applications.

Efficient elimination of co-existing antibiotics from saline mariculture wastewater poses significant challenges to conventional biological technologies. Here, we evaluated the membrane aerated biofilm reactor (MABR) coupled with short-cut nitrification and denitrification (SCND) for the simultaneous removal of co-existing tetracycline (TC), sulfamethoxazole (SMX), and norfloxacin (NOR) from mariculture wastewater. The MABR-SCND exhibited excellent antibiotic removal performance, achieving up to 100.0 %, 78.0 %, and 65.0 % removal for TC, SMX, and NOR, respectively, under co-existing condition. Biodegradation was the main removal pathway for TC and SMX, with biodegradation faster for TC, but NOR was removed primary by biosorption, which was controlled by electrostatic attraction and surface complexation. Additionally, the metabolic pathways analysis revealed that the lactamization of TC and the formation of beta-ketoadipic acid and succinic acid as key metabolites of TC and SMX contributed to their mineralization. Taxonomic analysis identified that Aequorivita, Hyphomicrobium, and Defluviimonas were important for biodegrading multiple antibiotics. Finally, the MABR-SCND sustained halotolerance by upregulating salt-tolerance genes oadA, proVWX, and opuBD. By offering comprehensive information into the fate of multiple antibiotics, this work supports that the MABR-SCND can provide robust treatment of multiple antibiotics from saline wastewater.

Microbial loss significantly affects wastewater treatment efficiency. This study simulated the inoculation area of a self-developed biological doubling reactor (BDR) to evaluate the retention efficiency of seven different fillers for aerobic denitrifying bacteria. Over 90 days of continuous operation, the porous filler R3 demonstrated excellent performance, with OD600 values consistently exceeding 1.0 and minimal fluctuation. On day 90, the seed liquid amplified with R3 achieved removal efficiencies of 100% for ammonia nitrogen, 97.75% for total nitrogen, and 96.4% for chemical oxygen demand, outperforming other fillers. Scanning electron microscopy and microscopic analysis revealed that R3's large large specific surface area and volume formed a unique meshed biofilm structure, enhancing oxygen and nutrient transport while minimizing detachment. This promoted effective enrichment and retention of aerobic denitrifying bacteria. Microbial diversity analysis confirmed that Acinetobacter, a key genus involved in aerobic denitrification, dominated the network biofilm on R3, accounting for an average of 35.63%. while granular fillers, due to oxygen limitation, promoted the growth of anaerobic ammonium-oxidizing Alcaligenes. The use of BDR-enhanced MBBR for treating synthetic wastewater resulted in a 29.6% increase in TN removal efficiency, with stable system operation. The use of porous fillers with a high specific volume supports stable biofilm formation and consistent seed liquid output, providing a viable solution to microbial loss in wastewater treatment processes.

The development of cost-effective oxygen evolution reaction electrocatalysts is rather meaningful and crucial for water electrolysis in alkaline electrolytes. Herein, we report a simple but feasible approach to prepare NiFe binary alloying coating on Fe plate through laser cladding technology, followed by various halogen-anion (F, Cl, Br) corrosion for optimizing the electrochemical reconstruction in oxygen evolution reaction process. Remarkably, the NiFe-F catalyst demonstrated superior OER activities with delivering typical current densities of 10 and 50 mA/cm2 at low overpotentials of 293 and 379 mV, respectively, and possessing a small Tafel slope of 55.2 mV/dec, both are rather lower than those of NiFe-Cl and NiFe-Br counterparts. Additionally, the binary alloy coating catalyst after F corrosion is exceptionally stable in alkaline electrolyte, showing no significant activity degradation for continuous oxygen production over 240 h. Multiple morphology/spectroscopy characterizations and insightful density functional theory (DFT) calculations demonstrate that more high-valence Ni3+ and Fe3+ centers can be introduced into the binary alloy coating electrode after F corrosion, which benefits the formation of highly-active oxyhydroxyl species (NiOOH, FeOOH), thereby contributing to the improved OER performance.

Heterotrophic nitrifying-aerobic denitrifying (HN-AD) bacteria with multi-stress tolerance hold significant potential for industrial wastewater treatment. In this study, a novel strain, Halomonas sp. ZC-1, was isolated from chemical wastewater and exhibited excellent nitrogen removal performance under low-temperature (10 degrees C) and high-salinity (0-13 %) conditions. Notably, at 10 degrees C and 10 % NaCl, ZC-1 achieved maximum ammonia and total nitrogen removal efficiencies of 94.9 % and 83.5 %, respectively, with a peak average ammonia removal rate of 3.36 mg/L/h. Transcriptomic analysis revealed that strain ZC-1 resists low-temperature and high-salinity stress through three key mechanisms: (1) upregulation of genes involved in osmoprotectant synthesis, such as betC and ectC, to regulate intracellular osmotic pressure; (2) activation of Na+ /H+ antiporters (mnhC, mnhE) and the K+ uptake gene phaF, maintaining ion homeostasis via the proton motive force; and (3) enhanced expression of 3-hydroxyacyl-[ACP] dehydratase (FabA) and beta-ketoacyl-[acyl-carrier-protein] synthase I (FabB), promoting fatty acid chain elongation and unsaturated fatty acid synthesis to lower membrane phase transition temperature. Furthermore, in practical applications treating saline wastewater at 10 degrees C, strain ZC-1 demonstrated ammonia and total nitrogen removal efficiencies of 66.92 % and 53.74 %, respectively. These findings elucidate the nitrogen removal mechanisms of ZC-1 under low-temperature and high-salinity conditions and highlight its potential as an effective candidate for treating complex industrial wastewater.

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Inoculating heterotrophic nitrification-aerobic denitrification bacteria (HN-AD) to enhance membrane bioreactor (MBR) efficiency may result in the loss of functional bacteria. Therefore, this study compares the application results of enhancing MBR with a self-designed biological amplifier coupled with HN-AD against the performance of conventional MBR. After enhancement, the MBR achieved a removal efficiency of 96.7

In order to reveal the influence of impact velocity (U-p) on the spalling and fracture behavior of single crystal nickel, a non-equilibrium molecular dynamics approach is adopted to investigate the free surface velocity curve, radial distribution function, atomic crystal structures, dislocations, and void evolution process. The results show that the critical impact velocity U-p for spalling behavior in single crystal nickel is 1.5 km/s, and when U-p <= 1.5 km/s the spallation mechanism is classical spallation damage and when U-p >1.5 km/s it behaves as micro-spallation damage. The pore number and distribution area, and stress distribution area under micro-spallation damage are much higher than those under classical spallation damage. The influence of impact velocity on the classical spalling damage behavior (U-p <= 1.5 km/s) is analyzed and the corresponding spalling strength is obtained, indicating that an accident of spalling strength occurs when U-p is 1.3 km/s. The spalling strength of single crystal nickel is influenced by the combined effects of stacking faults, phase transformation, and dislocation. As the nucleation and emission of dislocations increase, the spalling strength decreases. When U-p < 1.3 km/s, the spalling damage is mainly due to stacking faults. When U-p = 1.3 km/s, the spalling strength is mainly affected by the competition between stacking faults and phase transformation. When U-p > 1.3 km/s, spalling strength is predominantly influenced by the body-centered cubic (BCC) phase transformation mechanism (transformation path: FCC -> BCT -> BCC). This study reveals the impact velocity-dependent patterns, mechanisms, and effects on spalling damage and fracture, providing a theoretical basis for realizing the protective application of nickel-based materials under extreme impact conditions.

To further investigate the potential of heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria for practical applications, the HN-AD mixed bacteria HY-1 were enriched and domesticated in this study. After five generations of domestication, the mixture was able to remove 98% of ammonia nitrogen (400 mg/L) and 81.9% of mixed nitrogen source (nitrate, nitrite). Changes in community structure in the domestication process of mixed microorganisms were studied using 16S rDNA-seq. The results indicated an increase in the abundance of Acinetobacter from 16.9% to 80%. The conditions for the expanded culture of the HY-1 were also optimized. Moreover, A pilot-scale expanded reactor with a capacity of 1000L was constructed, and the HY-1 was successfully expanded from 0.1L to 800L. The community structures of the HY-1 remained stable after the expanded culture, with Acinetobacter as the dominant species. Moreover, the HY-1 demonstrated adaptability to actual high ammonia nitrogen wastewater and showed potential for practical application.

Molecular dynamics simulations were used to investigate the effect and mechanism of the angle (theta) between the plane of void center formation and the loading direction on void growth and coalescence behavior in single-crystal nickel under uniaxial tension. The results show that the yield stress and average flow stress of single-crystal nickel decrease with increasing theta, and the rate of stress decrease accelerates with increasing theta. When theta=90 degrees(loading direction perpendicular to the plane of void center), the independent growth time of voids in single- crystal nickel is the shortest and void coalescence occurs first, leading to the easiest way to entering the softening stage. This is due to the fastest growth rate of void volume fraction and damage evolution rate in single-crystal nickel when theta=90 degrees. When theta=90 degrees, the significant reduction of 1/6<112> (Shockley) dislocation length and the maximum transformation rate of atomic number from fcc crystal structure to Other and hcp crystal structures in single-crystal nickel lead to the fastest damage evolution rate and the most severe damage level. It is worth noting that voids in single-crystal nickel are most likely to coalesce when theta=90 degrees, due to the larger tensile stress on the void surface under this condition.

A novel heterotrophic nitrification and aerobic denitrification (HN-AD) strain CY-10 was isolated and identified as Sphingopyxis sp. When ammonium, nitrate or nitrite was used as the sole nitrogen source (300 mg/L), the maximum nitrogen removal efficiency of strain CY-10 were 100%, 91.1% and 68.5%, respectively. The optimal salinity for ammonia nitrogen removal by strain CY-10 was in the range of 0-5%. At the salinity of 5%, a maximum nitrogen removal rate of 6.25 mg/(L·h) was realized. Metabonomics data showed that the metabolic levels of sucrose and D-tagatose increased significantly at 5% salinity condition, enabling the strain to regulate osmotic pressure and survive in high-salt environments. Functional genes were successfully amplified by quantitative PCR, and HN-AD pathway of strain CY-10 followed NH4+-N → NH2OH → NO2--N → NO → N2O → N2. These findings show that strain CY-10 has great potential in nitrogen removal treatment of saline wastewater.

One of the biggest challenges of applying heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria to treat high salt organic wastewater lies in the inhibitory effect exerted by salinity. To study the inhibition effect and underlying mechanism induced by different ion types and ion composition, the individual and combined effects of NaCl, KCl and Na2SO4 on HN-AD bacteria Acinetobacter sp. TAC-1 were systematically investigated by batch experiments. Results indicated that the ammonia nitrogen removal yield and TAC-1 activity decreased with increased salt concentration. NaCl, KCl and Na2SO4 exerted different degrees of inhibition on TAC-1, with half concentration inhibition constant values of 0.205, 0.238 and 0.110 M, respectively. A synergistic effect on TAC-1 was found with the combinations of NaCl + KCl, NaCl + Na2SO4 and NaCl + KCl + Na2SO4. The whole RNA resequencing suggested that transcripts of denitrification genes (nirB and nasA) were significantly downregulated with increased Na2SO4 concentration. Simultaneously, Na2SO4 stress disrupted cell respiration, DNA replication, transcription, translation, and induced oxidative stress. Finally, we proposed a conceptual model to summarize the inhibition mechanisms and possible response strategies of TAC-1 bacteria under Na2SO4 stress.

The cometabolism mechanism of chlorinated hydrocarbon solvents (CHSs) in mixed consortia remains largely unknown. CHS biodegradation characteristics and microbial networks in methanotrophic consortia were studied for the first time. The results showed that all CHSs can efficiently be degraded via cometabolism with a maximum degradation rate of 4.8 mg/(h.g(cell)). Chloroalkane and chloroethylene were more easily degraded than chlorobenzenes by methanotrophic consortia, especially nonfully chlorinated aliphatic hydrocarbons, which were converted to Cl- with a production rate of 0.29-0.36 mg/(h.g(cell)). In addition, the microecological response results indicated that Methylocystaceae (49.0%), Methylomonas (65.3%) and Methylosarcina (41.9%) may be the major functional degraders in methanotrophic consortia. Furthermore, the results of the microbial correlation network suggested that interactive relationships constructed by type I methanotrophs and heterotrophs determined biodegradability. Additionally, PICRUSt analysis showed that CHSs could increase the relative abundance of CHS degradation genes and reduce the relative abundance of methane oxidation genes, which was in good agreement with the experimental results.

A novel heterotrophic nitrification and aerobic denitrification (HN-AD) strain CY-10 was isolated and identified as Sphingopyxis sp. When ammonium, nitrate or nitrite was used as the sole nitrogen source (300 mg/L) under aerobic condition, the maximum nitrogen removal efficiency of strain CY-10 were 100%, 91.1% and 68.5%, respectively. The functional genes were successfully amplified by quantitative PCR, and HN-AD pathway of strain CY-10 followed NH4+-N → NH2OH → NO → N2O → N2. The optimal salinity for ammonia nitrogen removal by strain CY-10 was in the range of 0-5%. At the salinity of 5%, a maximum nitrogen removal rate of 6.25 mg/(L·h) was realized. Metabonomics data showed that the metabolic levels of sucrose and D-tagatose increased significantly at 5% salinity condition, enabling the strain to regulate osmotic pressure and survive in high-salt environments. Strain CY-10 has great potential in nitrogen removal treatment of saline wastewater.

A novel strain was isolated from swinewastewater and identified as Acinetobacter sp. TAC-1 based on its phylogenetic and phenotypic characteristics. The strain TAC-1 was found to have a high ability to metabolize ammonium-N under low temperature condition. The strain TAC-1 could remove approximately 94.6% of ammonium-N (400 mg/L), 93.3% of nitrate-N (400 mg/L) and 42.4% of nitrite-N (400 mg/L) at 5 °C. The functional genes nitrate reductase gene (narG) and nitrite reductase gene (nirK, nirS) were successfully amplified by qPCR, further evidencing the heterotrophic nitrification and aerobic denitrification capability of Acinetobacter sp. TAC-1. The transcriptome data confirmed that the membrane transport protein and unsaturated fatty acid dehydrogenase-related genes of the strain TAC-1 were significantly up-regulated at 5 °C, enabling it to survive low temperatures. The high nitrogen removal ability at 5 °C makes this strain have a good application prospect.

A novel simultaneous nitrification and denitrification (SND) process using biodegradable polymers (BDPs) as the biofilm carrier and carbon source was developed to remove nitrogen from low-carbon sewage. The effects of BDPs types and hydraulic retention time (HRT) on nitrogen removal and microbial community composition were investigated. The results suggested that HRT parameters were tested in a range from 40h to 3h, and nitrogen removal performance was significantly worse with short HRT (13h to 3h). The NH4+-N and total nitrogen (TN) removal rates of the polycaprolactone (PCL) reactor reached to 98.40 % and 89.14 % at the optimal HRT (13h), respectively, and polybutylene succinate (PBS) reactor reached to 85.73 % and 81.64 %, respectively. When HRT was decreased from 13h to 3h, the NH4+-N removal rate of the PCL and PBS reactors were reduced to the lowest values of 55.43 % and 33.47 %, and the removal rate of TN also reduced to 55.53 % and 44.88 %. According to Illumina MiSeq sequencing and correlation analyses, the genera Methyloversatilis, Bdellovibrio, and Zoogloea were significantly, positively correlated with nitrogen removal rate and short HRT, and short HRT impacted TN removal through increasing the abundance of these genera. LEfSe analysis revealed that the differences observed between PCL and PBS reactors were dependent on differences in Methyloversatilis, ultimately resulting in differences in microbial communities related to nitrogen removal. KEGG analysis suggested that nitrification-related functional genes (amoA, amoB, amoC, and hao) had the greatest abundance in the 13h HRT condition, and denitrification-related functional genes (napA, napB, nasA, nirS, and nosZ) were generally more abundant in the PBS system than the PCL system.