Journal of Environmental Sciences-china最新文献

A biochar-assisted anaerobic membrane bioreactor (BC-AnMBR) was conducted to evaluate the performance in treating swine wastewater with different organic loading rates (OLR) ranging from 0.38 to 1.13 kg-COD/(m^3.d). Results indicated that adding spent coffee grounds biochar (SCG-BC) improved the organic removal efficiency compared to the conventional AnMBR, with an overall COD removal rate of > 95.01%. Meanwhile, methane production of up to 0.22 LCH₄/gCOD with an improvement of 45.45% was achieved under a high OLR of 1.13 kg-COD/(m^3.d). Furthermore, the transmembrane pressure (TMP) in the BC-AnMBR system was stable at 4.5 kPa, and no irreversible membrane fouling occurred within 125 days. Microbial community analysis revealed that the addition of SCG-BC increased the relative abundance of autotrophic methanogenic archaea, particularly Methanosarcina (from 0.11% to 11.16%) and Methanothrix (from 16.34% to 24.05%). More importantly, Desulfobacterota and Firmicutes phylum with direct interspecific electron transfer (DIET) capabilities were also enriched with autotrophic methanogens. Analysis of the electron transfer pathway showed that the concentration of c-type cytochromes increased by 38.60% in the presence of SCG-BC, and thus facilitated the establishment of DIET and maintained high activity of the electron transfer system even at high OLR. In short, the BC-AnMBR system performs well under various OLR conditions and is stable in the recovery energy system for swine wastewater.

Advanced oxidation processes (AOPs) exhibit significant potential for water disinfection due to their generation of large quantities of highly oxidizing free radicals. However, the neglect of viable but nonculturable (VBNC) cells obscures their true disinfection efficacy and potential environmental health risks. Therefore, the study evaluated the disinfection effectiveness and mechanisms of typical AOPs, including Fe/H₂O₂, Fe/persulfate (PS), and O₃, from the perspective of the production of VBNC bacteria. The results indicate that Fe/PS exhibits the strongest bacterial inactivation rate (99.94%), and the cells lose their ability to reactivate. Fe/H₂O₂ and O₃ induce more cells to enter the VBNC state compared to Fe/PS. Moreover, different AOPs result in varying levels of free radical production and utilization efficiency, with SO₄^•− and O₃ exhibiting greater selectivity in deactivating bacteria compared to HO^•. The inhibition of VBNC bacteria production by Fe/PS treatment may be attributed to the combined action of HO^• and SO₄^•− on microorganisms, leading to oxidative stress and metabolic disruption in bacteria through the inhibition of biofilm formation and aminoacyl-tRNA biosynthesis (p < 0.05), thereby causing direct bacterial death rather than entry into the VBNC state. In contrast, Fe/H₂O₂ and O₃ result in the upregulation of the metabolism of alanine, aspartate, and glutamate, as well as styrene degradation capacity by the bacteria, leading to the production of more VBNC bacteria. Overall, the study offers insights into mitigating potential biological risks in water disinfection and developing environmentally friendly and efficient disinfection technologies.

Environmental residues of the fungicide difenoconazole (DFZ) have been shown to pose a threat to mammals. However, the risk assessment of DFZ for cultured carp remains unclear. The aim of this study was to investigate the adverse effects of DFZ on carp liver and their molecular mechanisms by simulating the environmental contamination concentrations of DFZ. Our results showed that DFZ induced structural damage in the liver, including edema, vacuolation, and congestion. In addition, DFZ residues were detected in liver tissues. Mechanistically, DFZ causes mitochondrial dysfunction by promoting Ca²⁺ transfer from the endoplasmic reticulum (ER) to mitochondria via IP3R, leading to the onset of ROS burst and apoptosis, and the inhibition of Nrf2 antioxidant function by DFZ also results in uncontrolled ROS. Mitophagy was also activated intracellularly to counteract mitochondrial damage. Interestingly, treatment with 2-APB alleviated mitochondrial dysfunction, restored the mitochondrial membrane potential, and inhibited apoptosis by blocking the translocation of Ca²⁺ from the ER to the mitochondria. Metabolomic analysis revealed that DFZ disrupted energy metabolism in carp liver, whereas 2-APB reversed DFZ-induced metabolic alterations. In conclusion, the present study elucidates the threat of DFZ to carp liver and highlights the mechanism of damage, thereby helping to explain the impact of agriculture on the aquatic environment.

The effects of disinfectants and plasmid-based antibiotic resistance genes (ARGs) on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinking water distribution system under simulated conditions were explored. The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH₂Cl was higher than in the control groups. There was no similar phenomenon in biofilm. In the water of reactors containing NaClO, the aphA and bla genes were lower than in the antibiotic resistant bacteria group, while both genes were higher in the water of reactors with NH₂Cl than in the control group. Chloramine may promote the transfer of ARGs in the water phase. Both genes in the biofilm of the reactors containing chlorine were lower than the control group. Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm (p < 0.05). The results of the sequencing assay showed that bacteria in the biofilm, in the presence of disinfectant, were primarily Gram-negative. 1.0 mg/L chlorine decreased the diversity of the community in the biofilm. The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.

Red anaerobic ammonia oxidation (Anammox) granular sludge (AnGS) has been reported in successfully operating Anammox systems, and its color is associated with sludge activity. However, in long-term operating systems, AnGS exhibits different sensory colors, physical structures, community structures, and denitrification performance, but the relationship between them has not yet been elucidated. The AnGS of the Anammox system, which has been in operation for more than a decade, can be divided into two main categories: red and white. The specific Anammox activity (SAA) in conventional red AnGS increased continuously as the particle size increased from <0.51 mm to 6.02 ± 0.84 mm. The SAA of white AnGS were slightly lower than those of red AnGS with similarly-size granules but significantly higher than AnGS with smaller red granules. Compared with red AnGS, the extracellular polymeric substances of white AnGS were significantly reduced, mainly due to the higher intracellular iron content, resulting in lower heme c concentration. Thus, heme c may prove not to be an evaluative tool for measuring Anammox activity. Red and white AnGS, whether through self-aggregation or adsorption by hydroxyl apatite and other carriers, will face the fate of internal voids during particle size growth. White AnGS exhibited a more complex microbial community than red AnGS. Candidatus Brocadia was abundant in red AnGS and the abundance increased with increasing granule size. Candidatus Kuenenia and Candidatus Jettenia made significant contributions to denitrification in white AnGS. This study provides a new perspective on particle selection for anammox engineering applications.

Selective catalytic reduction of NO_x with CO (CO-SCR) is a process that purifies both NO and CO pollutants through a catalytic reaction. Specifically, the cleavage of NO on the catalyst surface is crucial for promoting the reaction. During the reaction, the presence of oxygen vacancies can extract oxygen from NO, thereby facilitating the cleavage of NO on the catalyst surface. Thus, the formation of oxygen vacancies is key to accelerating the CO-SCR reaction, with different types of oxygen vacancies being more conducive to their generation. In this study, Rh/CeCuO_x catalysts were synthesized using the co-crystallization and impregnation methods, and asymmetric oxygen vacancies were induced through hydrogen thermal treatment. This structural modification was aimed at regulating the behavior of NO on the catalyst surface. The Rh/Ce_0.95Cu_0.05O_x-H₂ catalyst exhibited the best performance in CO-SCR, achieving above 90% NO conversion at 162 °C. Various characterization techniques showed that the H₂ treatment effectively reduced some of the CuO and Rh₂O₃, creating asymmetric oxygen vacancies that accelerated the cleavage of NO on the catalyst surface, rather than forming difficult-to-decompose nitrates. This study offers a novel approach to constructing oxygen vacancies in new CO-SCR catalysts.

Integrating photocatalysis technology with peroxymonosulfate oxidation possesses huge potential for degrading stubborn pollutant. Herein, a porous ultra-thin carbon nitride with C-defect O-doping and advanced n-π* transition was customized by one-pot thermal-induced polymerization of molten urea assisted with paraformaldehyde. Via visible-light coupling peroxymonosulfate activation, the DCN-100 can completely photodegrade 2,4-dichlorophenol, and rate constant is 136.6 and 37.9 times that of CN and DCN-100 without peroxymonosulfate. The light-absorption of DCN-100 surpasses 550 nm, specific surface area rises from 45.03 to 98.58 m²/g, and charge behaviors are significantly improved. The effects of paraformaldehyde amount, PMS dosage, pH, 2,4-dichlorophenol concentration, different water-body, wavelength and recycling times on photodegradation performance were explored in detail. Via capture experiments, ESR, LC-MS, Fukui-function, TEXT toxicity assessment and DFT theoretical calculation, the main active substances, degradation pathway, intermediate toxicity and enhanced activity mechanism of DCN-100 were clarified. The research provides a cost-effective, high-efficiency and environmental-friendly photocatalysts to activate peroxymonosulfate for water remediating.

Porphyrinic hydrogen-bonded organic frameworks (porph-HOFs) have emerged as highly promising materials in the realm of photocatalysis due to their remarkable attributes, including low density, high surface area, efficient visible light absorption, and notable chemical stability. However, the rapid recombination of photogenerated charges remains a significant concern. In this work, a novel HOF-based photocatalyst, PFC-72/TiO₂ was successfully designed with visible light response and high electron transfer capability. This involved bonding TiO₂ nanoparticles to the PFC-72 framework synthesized using cobalt porphyrin as organic ligand and introducing bridging molecules 4-mercaptopyridine (4-PySH). Moreover, sulfadiazine (SDZ), a highly prevalent antibiotic, was effectively degraded from wastewater using PFC-72/TiO₂. The high specific surface area of PFC-72 significantly improved the dispersion of TiO₂ in PFC-72/TiO₂, providing more active sites and improving the ability to adsorb SDZ. Characterizations and density functional theory analysis further confirmed that the photosensitization effect of porph-HOF extended the response range of TiO₂ in PFC-72/TiO₂ and reduced the recombination efficiency of photogenerated charges, consequently enhancing photocatalytic performance. Additionally, due to significantly improved robustness of PFC-72 and its axial coordination interaction with 4-PySH, PFC-72/TiO₂ displayed excellent stability and recyclability. Consequently, optimized PFC-72/TiO₂ exhibited a remarkable SDZ removal efficiency of 93.73% within 120 min, maintaining consistent photoactivity even after undergoing four cycles. Furthermore, intermediate products and degradation pathways were proposed based on UPLC-MS/MS.

This study introduced a microwave-assisted pyrolysis method for the rapid and efficient preparation of boron-doped porous biochar. The resulting biochar exhibited a large specific surface area (933.39 m²/g), a rich porous structure (1.044 cm³/g), and abundant active sites. Consequently, the prepared boron-doped porous biochar exhibited higher efficiency in adsorbing tetracycline with a maximum adsorption capacity of 413.223 mg/g, which significantly exceeded that of unmodified biochar and most commercial and reported adsorbents. The correlation analysis between the adsorption capacity and adsorbent characteristics revealed that the formation of the –BCO₂ group enhanced π–π electron donor–acceptor interactions between boron-doped porous biochar and tetracycline. This mechanism mainly contributed to the enhanced adsorption of tetracycline by boron-doped porous biochar. Additionally, the as-prepared boron-doped porous biochar exhibited broad applications in removing antibiotics (tetracycline), phenolics (bisphenol A), and dyes (methylene blue and rhodamine B). Moreover, the boron-doped porous biochar exhibited satisfactory stability, and its adsorption capacity can be nearly completely regenerated through simple heat treatment. This study provides new insights into the effectiveness of boron-doped carbonaceous materials in removing antibiotic contaminants.

Three lanthanum morphology materials encompassing all lanthanum composites were synthesized by the direct precipitation method, and their phosphate adsorption order was determined as La₂(CO₃)₃ > La(OH)₃ > La₂O₃. Further comparison of the adsorption performance between La₂(CO₃)₃ and La(OH)₃ revealed that the former exhibited a twofold higher rate of adsorption compared to the latter. The presence of SO₄²⁻, HCO₃⁻, Mg²⁺, and HA in the water led to a decrease in the phosphate adsorption of La₂(CO₃)₃ and La(OH)₃, while Ca²⁺ enhances the adsorption of phosphoric acid by both materials. Compared to La₂(CO₃)₃, La(OH)₃ exhibited stronger resistance against coexisting ions. The pH was the limiting factor for phosphate adsorption in both cases, and their adsorption capacity decreased significantly as the pH increased. The phosphate adsorption mechanism of La₂(CO₃)₃ was ligand exchange to form inner-sphere complexes, while the phosphate adsorption mechanism of La(OH)₃ involved ligand exchange, inner-sphere complexation, and electrostatic attraction. The stability of La(OH)₃ exhibited superior performance compared to that of La₂(CO₃)₃ over 5 adsorption-desorption cycles. Although La₂(CO₃)₃ had a higher initial phosphate adsorption capacity than La(OH)₃, its phosphate adsorption capacity decreased by 40% after five adsorption-desorption cycles, while that of La(OH)₃ decreased by 2.3%. Additionally, the amount of La(OH)₃ adsorbed after five cycles was 25.6% higher than that of La₂(CO₃)₃. Therefore, La(OH)₃ performs better regeneration adsorption than La₂(CO₃)₃. Furthermore, a smaller dosage of La(OH)₃ was required compared to La₂(CO₃)₃ in a test aimed at lowering the actual phosphate concentration in water to 0.5 mg/L. In summary, La(OH)₃ is a more suitable substrate for cyclic adsorption for phosphorus removal than La₂(CO₃)₃ and has better potential for practical application. In conclusion, La(OH)₃ proves to be a more suitable substrate for cyclic adsorption in phosphorus removal compared to La₂(CO₃)₃ and exhibits superior potential for practical application.