Frontiers of Environmental Science & Engineering最新文献

During the COVID-19 pandemic, most sewage treatment plants increased disinfectant dosages to inactivate pathogenic viruses and microorganisms more effectively. However, this approach also led to the production of more disinfection by-products (DBPs). To ensure both disinfection efficiency and a reduction in DBP formation, new disinfection protocols are required. In this study, the disinfection efficiency, DBP amounts, and toxicity changes resulting from ozone (O₃), ultraviolet (UV), chlorine (Cl₂), and their combined processes were examined. The results demonstrated that the O₃/UV/Cl₂ combination achieved the highest disinfection efficiency. Chlorination produced the most DBPs, whereas UV treatment reduced the formation of trihalomethane (THM), halogenated ketones (HKs), haloacetic acids (HAA), dichloroacetonitrile (DCAN) and N-nitrosodimethylamine (NDMA) by 45.9%, 52.6%, 82.0%, 67.95%, and 47%, respectively. O₃ also significantly reduced their production by 99.1%, 91.1%, 99.5%, 100%, and 35%. Intracellular organic matter (IOM) was identified as the primary DBP precursors, producing 2.94 times more DBPs than extracellular organic matter (EOM). The increased DBP formation during chlorination was attributed to IOM leakage and cell membrane damage, which was verified using scanning electron microscopy (SEM). The toxicities of DBPs were evaluated for six disinfection methods, revealing inconsistent results. The overall toxicities were assessed using zebrafish embryo experiments. Both evaluations indicated that chlorination alone was the least favorable method. In addition, the toxicities followed a sequence: Cl₂ ≈ O₃/Cl₂ > O₃ > O₃/UV/Cl₂ > UV > UV/Cl₂. These findings can serve as a reference for sewage treatment plants in selecting appropriate disinfection methods to manage the COVID-19 epidemic from comprehensive perspective.

Measurements studies have shown that the absorption of radiation by black carbon (BC) increases as the particles age. However, there are significant discrepancies between the measured and modeled absorption enhancement (E_abs), largely due to the simplifications used in modeling the mixing states and shape diversities. We took advantage of chamber experiments on BC aging and developed an efficient method to resolve the particle shape based on the relationship between the coating fraction (ΔD_ve/D_ve,0) and fractal dimension (D_f), which can also reflect the variations of D_f during the whole BC aging process. BC with externally and partly mixed states (0 ⩽ ΔD_ve/D_ve,0 ⩽ 0.5) can be considered to be uniformly distributed with the D_f values of 1.8–2.1, whereas the D_f values are constrained in the range 2.2–2.8 for fully mixed states (ΔD_ve/D_ve,0 > 0.5). The morphological parameters (i.e., the effective density and the dynamic shape factor) were compared with the measured values to verify the simulated morphology. The simulated mean deviations of morphological parameters were smaller than 8% for the method resolving the particle shape. By applying a realistic shape and refractive index, the mass absorption cross for fully mixed states can be improved by 11% compared with a simplified core–shell model. Based on our understanding of the influence of D_f and ΔD_ve/D_ve,0 on E_abs, we propose a two-stage calibration equation to correct the E_abs values estimated by the core–shell model, which reduces the simulation error in the Mie calculation by 6%–14%.

Red soil, the most critical soil resource in tropical/subtropical regions worldwide, faces tremendous threats, including nutrient deficiency, acidification, and heavy metal contamination. There is a great demand for multifunctional eco-materials capable of modifying this situation. Herein, we used widely distributed soil and biomass to develop a zeolite/biochar composite for synergistic red soil remediation and amendment. With the composite material, the Pb²⁺ and Cd²⁺ remediation efficiencies reached 92.8% and 92.9%, respectively, in stems under optimal conditions. Moreover, the acidity and nutrient deficiency conditions of red soil significantly improved. The atomic-scale interaction mechanism during the remediation and amendment process was elucidated with complementary characterization methods, which revealed that in the zeolite/biochar composite material, zeolite contributes to long-term heavy metal remediation effects. Simultaneously, biochar is responsible for soil quality amendment and short-term heavy metal remediation. Furthermore, for the first time, single-atom heavy metal ions were observed on biochar during the remediation process, indicating the broad distribution of single atoms in the natural environment.

The addition of traditional carbon sources (e.g., acetate) could favor heterotrophic overgrowth in partial denitrification coupled with anammox (PD–A) systems, thus hindering the performance and stability of this novel wastewater nitrogen removal technology. Therefore, it is necessary to develop an effective, environmentally friendly, and inexpensive alternative. This study demonstrated the potential of formate to enhance the performance and community stability of PD–A under mainstream conditions. In a laboratory-scale biofilm reactor, formate addition (COD/NO₃⁻–N = 1.75) improved nitrogen removal efficiency (from 72.1 ± 3.5% to 81.7 ± 2.7%), EPS content (from 106.3 ± 8.1 to 163.0 ± 15.5 mg/gVSS) and increased anammox bacteria growth (predominantly Candidatus Brocadia, from 29.5 ± 0.7% to 34.5 ± 5.4%) while maintaining stable heterotrophs dominated by methylotrophic Desulfobacillus. FISH-NanoSIMS revealed a formate uptake using Ca. Brocadia and Desulfobacillus, with Ca. Brocadia being the major contributor to partial nitrate reduction to nitrite. Desulfobacillus can synthesize diverse hydrophobic amino acids and provide key nutrients for Ca. Brocadia. To achieve comparable nitrogen removal, the cost of the formate-driven PD–A process should be 11.2% lower than that of acetate. These results greatly enrich our understanding of C1 metabolism represented by formate in anammox communities and its application in the context of coupling partial denitrification-anammox toward enhanced nitrogen removal in global wastewater treatment systems.

Nationwide longitudinal evidence linking cognitive decline with exposure to fine particulate matter (PM_2.5) constituents remains scarce in China. By constructing a dynamic cohort based on the China Health and Retirement Longitudinal Study, we aimed to assess individual and joint associations of PM_2.5 constituents with cognitive function among middle-aged and older adults in China. Linear mixed-effects models incorporated with quantile-based g-computation were applied to investigate individual and joint associations of long-term exposures to PM_2.5 constituents with cognitive function. Among 13,507 respondents, we evaluated 38,950 follow-up records of cognitive function tests. Declines in global cognitive score associated with an interquartile range (IQR) increase in exposure were −1.477 (95% CI: −1.722, −1.232) for nitrate, followed by −1.331 (−1.529, −1.133) for ammonium, −1.033 (−1.184, −0.883) for sulfate, −0.988 (−1.144, −0.832) for organic matter and −0.822 (−0.946, −0.699) for black carbon. An IQR-equivalent increase in joint exposure to these PM_2.5 constituents was associated with a decline of −1.353 (−1.659, −1.048) in global cognitive score. Female, younger, and well-educated individuals were at greater vulnerability to cognitive impairment related to individual and joint exposure to PM_2.5 constituents. This study suggested that later-life exposures to PM_2.5 constituents were associated with cognitive decline in middle-aged and older adults in China.

Climate change leads to an increase in both the frequency and intensity of extreme precipitation. Surface runoff generated by extreme precipitation has a significant impact on water. However, the impact of persistent precipitation on surface water quality is easy to neglect, due to its prolonged duration and lower-intensity rainfall. This study established eight sampling points within selected surface waters to observe the variation of microbial characteristics in a typical persistence precipitation event. The primary difference between Furong Lake (FL) and Chengqian Reservoir (CR) was: the concentrations of dissolved organic carbon (DOC) were 21.3 ± 0.7 and 8.3 ± 1.5 mg/L in FL and CR, respectively. The concentrations of R2A culturable bacteria and coliforms were 10^4.57 and 10^1.58 colony-forming units (CFU)/mL in FL, and were 10^5.46 and 10^2.64 CFU/mL in CR, respectively. During precipitation, the maximum increase concentrations of R2A, NA culturable bacteria, and coliforms were 10^0.75, 10^1.30, and 10^2.27 CFU/mL in FL, respectively. Furthermore, microbial concentration and rainfall did not increase simultaneously, and a delay phenomenon was observed in the increasing microbial concentrations. Through analyzing the concentration change trends and correlation of various water quality indicators during persistent precipitation, the significant correlation between the DOC concentration and the changes in the dominant species of microbial community structure was found in this study (p < 0.05). For example, as the DOC concentration declined, the abundance of hgcl_clade and CL500-29_marine_group increased. Consequently, although persistent precipitation might not obviously alter the water quality visibly, it could still pose potential microbial risks.

Saline wastewater is regarded as a challenge for wastewater treatment plants because high-salinity conditions negatively affect on traditional biological technologies. Aerobic granular sludge (AGS) has gained attention as a promising technology for saline wastewater treatment because of its compact structure and the ability to withstand toxic loadings. Therefore, this study investigated the salt-resistance performance, sludge properties and microbial community of AGS under low-salinity and high-salinity conditions, with the saline concentrations ranging from 0 to 50 g/L. The results showed that AGS could withstand long-term saline stresses, and the maximum salinity reached 50 g/L within 113 d. Under salinities of 10, 30, and 50 g/L, the chemical oxygen demand (COD) removal efficiencies were 90.3%, 88.0% and 78.0%, respectively. AGS also its maintained strength and aggregation at salinities of 10 and 30 g/L. Overproduction of extracellular polymeric substances (EPS) by non-halophilic bacteria that enhanced sludge aggregation. The compact structure that ensured the microorganisms bioactivity helped to remove organic matters under salinities of 10 and 30 g/L. At a salinity of 50 g/L, moderately halophilic bacteria, including Salinicola, Thioclava, Idiomarina and Albirhodobacter, prevailed in the reactor. The dominant microbial communities shifted to moderately halophilic bacteria, which could maintain aerobic granular stabilization and remove organic matters under 50 g/L salinity. These results in this study provide a further explanation for the long-term operation of AGS for treating saline wastewater at different salinities. It is hoped that this work could bring some clues for the mystery of salt-resistance mechanisms.

Concerns related to environmental risks associated with pharmaceuticals and personal care products (PPCPs) have led researchers to seek methods for assessing and monitoring these contaminants in the aquatic environment. Identifying and validating risk assessment tools that can evaluate ecological concerns and risks associated with PPCPs is critical. Herein, the suitability of a dose-related risk and effect assessment model, which estimates predicted environmental concentrations and allowed comparisons with predicted no effect concentrations determined, in combination with in vitro analyses of the whole effluent toxicity, was verified for the characterization of a PPCP hazard. Concentrations of the most utilized PPCPs in Norway were measured in influent and effluent samples and used to parameterize the fate model.

Greater than 90% removal was attained for 12 out of 22 detected PPCPs. Removal was not dependent on the class or the concentration of the specific substance and varied between 12% and 100%. The PPCPs detected in the discharged wastewater were utilized to assess individual contributions to the risk of the effluent, and no risk was identified for the targeted 30 PPCP. The simulations provided valuable information regarding the discharge plume distribution over time, which can aid planning of future environmental monitoring investigations.

Bioassays (using fish liver cells, PLHC-1) were used for assessing overall effluent toxicity, through cell viability, production of reactive oxygen species, and ethoxyresorufin-O-deethylase (EROD) activities.

The present study may allow regulators to use risk-based strategies over removal criteria for monitoring studies and confirms the importance to take PPCP contamination into consideration when establishing environmental regulations.

Antibiotic resistance genes (ARGs) might have great effect on ecological security and human health. Oceans are important reservoirs that receive tremendous amounts of pollutants globally. However, information on the proliferation of ARGs in seawater is still limited. This study performed field sampling to investigate the occurrence and distribution of ARGs in seawater of the South China Sea, which is the deepest and largest sea in China. The results showed that the total absolute abundances of ARGs in seawater samples ranged from 2.1 × 10³ to 2.3 × 10⁴ copies/mL, with an of 5.0 × 10³ copies/mL and a range of 2.2 × 10³–1.8 × 10⁴ copies/mL for those with mobile genetic elements (MGEs). Genes resistant to multidrug, aminoglycoside, tetracycline, and fluoroquinolone antibiotics accounted for 77.3%–88.6% of total ARGs in seawater. Proteobacteria and Cyanobacteria represented 32.1%–56.2% and 30.4%–49.5% of microbial community, respectively. Prochlorococcus_MIT9313 and Clade_la were the prevalent genera in seawater of the South China Sea. Complex co-occurrence relationship existed among ARGs, MGEs, and bacteria. Anthropogenic activities had critical influence on ARGs and MGEs. Hospital wastewater, wastewater treatment plant effluent, sewage, aquaculture tailwater, and runoff were determined as the important sources of ARGs in seawater of the South China Sea based on positive matrix factorization analysis.

Photocatalysis-assisted removal of uranium has been proven as an effective method for the elimination of radioactive pollution from wastewater. In this work, carbon nitride materials were synthesized in potassium hydroxide (KOH) molten salt and applied to photocatalytic uranyl extraction. Obtained materials were confirmed to possess the triazine-s-heptazine structure by NMR, XPS and UV-Vis characterization, and exhibited a wider visible light absorption than graphitic carbon nitride (g-C₃N₄). The photocatalytic activity of the carbon nitride materials was tailored by varying the precursor mass fractions. The carbon nitride obtained at 80% melamine as precursor (K-CN-80) exhibited the highest photocatalytic extraction ability and its photocatalytic reaction rate is 6.6 times faster than that of g-C₃N₄. The influence of sacrificial agents was studied and the results showed that triethanolamine inhibited U(VI) photoreduction, but methanol can accelerate U(VI) photoreduction by consuming photogenerated holes. This unary KOH molten salt synthesis method has exceptional potential applications in the preparation of carbon nitrides, and the obtained products showed potential in extracting U(VI) from aqueous solutions for use in nuclear fuel industry and for U(VI) environmental pollution cleanup.