Frontiers of Environmental Science & Engineering最新文献

The environmental pollution caused by psychotropic drugs harms human health and has prompted a stronger emphasis on research into water treatment measures. The UV/Chlorine-biological activated carbon (BAC) combined process was employed in this study to treat amitriptyline (AMT), a typical psychotropic drug, in slightly contaminated drinking water. The removal efficiency of AMT in drinking water by UV/Chlorine and the feasibility of combining it with BAC were determined. The results demonstrated that the removal efficiency of 1 μmol/L AMT could reach 98.5% of the 2.0 mg/L chlorine and UV treated for 30 min. A significant removal improvement of AMT was 10%–45% compared to UV alone, Chlorine alone, and other oxidants combined, especially the SOUR (Specific Oxygen Uptake Rate), which was 57%–90% compared to other oxidants combined. Secondly, the optimal process parameters for UV/Chlorine-BAC treatment of slightly contaminated drinking water were a combination of UV exposure, chlorine dosage of 2 mg/L, and reaction times of 15 min followed by 30 min of BAC treatment. The AMT degradation, COD_Mn removal efficiency, and NO₃⁻–N production was 88%, 65%, and 95%, respectively. There was no significant effect on the number of microorganisms in the BAC medium, ensuring good long-term operation. Furthermore, an investigation was conducted to assess the influence of optimal process operation on the microbial community structure within BAC. This analysis unveiled a positive feedback loop in the colony architecture after implementing ideal process parameters. This study provides significant inspiration for addressing residual antidepressant issues using traditional drinking water treatment processes.

This review covers the decomposition mechanisms of various printing ink binder resins, with a particular focus on their behavior under extrusion conditions in the mechanical recycling process of polyolefin (PO) based plastic packaging. Thermal degradation and hydrolysis of the nitrocellulose (NC) — the most used binder for flexographic surface printing on single-layer flexible plastic packaging, occur concurrently during the mechanical recycling process under 160–210 °C. For other printing ink binders, polyurethane (PU) noticeable degradation takes place between 200 and 300 °C, mostly above 250 °C. However, with the involvement of humidity, degradation by hydrolysis can start from 150 °C. A similar effect is also discovered with the cellulose acetate (CA) derivatives, which are thermally stable until 300 °C and can be hydrolyzed at 100 °C. The thermal stability of polyvinyl butyral (PVB) is not influenced by humidity, with thermal stability ranging from 170 to 260 °C, depending on different types. Ultraviolet (UV)-cured acrylics are thermally stable until 400 °C. The hydrolysis degradation can take place at room temperature. Moreover, this review covers the thermal stability of different colorants used for printing ink application and elaborates on several thermal-stable alternatives of some common colors. This study further reviews how the binder resin affects the quality of recyclates, revealing it to be not only induced by the degradation of the binder resin but also by the immiscibility between the plastic and binder resin. In advanced recycling processes, mainly selective dissolution-precipitation and pyrolysis, the presence of binder resin and its degradation products could still affect the quality of the product. This review accentuates the imperative need for in-depth research to unravel the impact of printing ink constituents on the quality of recycled products.

Few studies investigated the effects of exposure to NO₂ on health status in the Chinese floating population. The present cross-sectional study evaluated the association of ambient NO₂ with health status in a floating population in China. Data on 168961 floating individuals in 338 cities were obtained from the 2017 China Migrants Dynamic Survey. The association between exposure to NO₂ and self-related health (SRH) status was assessed by binary logistic regression analysis, both in the entire subject cohort and in subgroups assorted by socioeconomic levels and demographic characteristics. The robustness of the associations between NO₂ exposure and health status was evaluated by sensitivity analyses. Each grade increment of annual average NO₂ exposure was found to increase the risk of poor SRH by 2.4% in the floating population (odds ratio [OR] = 1.024, 95% confidence interval [CI]: 1.011–1.038). When subgrouped by age, subjects in the floating population aged 31–49 years had the highest NO₂ associated health risk (OR = 1.036, 95% CI: 1.018–1.054). When subgrouped by per capita gross domestic product (PGDP), subjects in regions with mid-level PDGP had the highest NO₂ associated SRH (OR = 1.116, 95% CI: 1.091–1.141). These findings indicated that exposure to NO₂ increases the risk of poor SRH in the floating population, with individuals aged 31–49 years and those living in mid-level PGDP regions being more sensitive to the adverse effects of NO₂. More effective strategies to reduce air pollution may improve the health status of the floating population in China.

The human microbiome leaves a legacy in sewage ecosystems, also referred to as the human sewage microbiomes (HSM), and could cause potential risk to human health and ecosystem service. However, these host-associated communities remain understudied, especially at a global scale, regarding microbial diversity, community composition and the underlying drivers. Here, we built a metagenomic read mapping-based framework to estimate HSM abundance in 243 sewage samples from 60 countries across seven continents. Our approach revealed that 95.03% of human microbiome species were identified from global sewage, demonstrating the potential of sewage as a lens to explore these human-associated microbes while bypassing the limitations of human privacy concerns. We identified significant biogeographic patterns for the HSM community, with species richness increasing toward high latitudes and composition showing a distance-decay relationship at a global scale. Interestingly, the HSM communities were mainly clustered by continent, with those from Europe and North America being separated from Asia and Africa. Furthermore, global HSM diversity was shown to be shaped by both climate and socioeconomic variables. Specifically, the average annual temperature was identified as the most important factor for species richness (33.18%), whereas economic variables such as country export in goods and services contributed the most to the variation in community composition (27.53%). Economic and other socioeconomic variables, such as education, were demonstrated to have direct effects on the HSM, as indicated by structural equation modeling. Our study provides the global biogeography of human sewage microbiomes and highlights the economy as an important socioeconomic factor driving host-associated community composition.

Class 1 integrons are vital mobile genetic elements involved in the environmental transmission of antibiotic resistance genes (ARGs). However, knowledge about the diversity and abundance of class 1 integrons and gene cassettes during drinking water treatment and distribution is still limited. In this study, we aimed to uncover the prevalence of class 1 integrons in the drinking water treatment and distribution systems with the combination of culture-dependent and culture-independent methods. Further, we applied the nanopore sequencing method to characterize the diversity and arrangement of ARGs carried by class 1 integron-associated gene cassettes. A total of 42 isolates were intI1-positive among the 208 strains isolated from drinking water, which tended to confer multi-drug resistance compared with intI1-negative isolates. The absolute abundance of the intI1 average 1.15 × 10⁹ copies/L in the source water and underwent the most significant reduction of over 99.9% after liquid chlorine disinfection. Furthermore, nanopore sequencing revealed that the class 1 integron-associated gene cassettes carried 51 subtypes of ARGs in drinking water, mainly conferring resistance to aminoglycosides and trimethoprim. The treatment processes, especially liquid chlorine disinfection, reduced most of the ARGs carried by gene cassettes, though some of the ARG subtypes persisted along the treatment and distribution like aac(6′)-II, aadA, and dfrB2. The antibiotic resistance gene cassette array ∣aac(6′)-II∣arr∣ was most frequently detected, especially in the chlorinated water. This study underlined that drinking water was potential reservoir for integron-mediated ARGs transfer, indicating that the health risks of resistance gene cassettes in class 1 integrons deserved urgent attention.

Municipal solid waste (MSW) storage sites are potential and overlooked contributors to microplastic (MP) pollution. Herein, the distribution and dispersion characteristics of MPs at MSW storage sites were investigated through modeling, sampling analysis, and prediction methodologies. The results indicated a notable adsorption phenomenon of MPs on smooth surfaces within such sites, achieving high saturation levels and making MPs prone to re-release by airflow disturbance. Quantitative analysis revealed that the MP concentrations on these surfaces varied from 4.48 × 10⁵ to 1.90 × 10⁶ n/m² and that MPs predominantly accumulated in the corner areas. Notably, MP accumulation on wall surfaces can be reduced by 76.4% using washing procedures. The majority of MPs were under 50 µm in size and were primarily in fragment form. Operational activities such as ventilation and waste handling were identified to amplify the airborne spread of MPs. The atmospheric concentrations of MPs peaked seasonally, with concentrations of 28.25 n/m³ in summer and 3.90 n/m³ in winter, and the spatial dispersion ranged from 14.98 to 124.08 km² per station. This study highlights that MSW storage sites are substantial yet overlooked sources of MP pollution, where wall surfaces play a critical role in MP adsorption and dispersal. The implementation of robust management and cleaning protocols is essential to mitigate the environmental footprint of MPs emanating from these locations. This study also provides a typical case for the precise prevention and control of MPs in the environment.

Emerging pollutants, such as antibiotics and antibiotic-resistance genes, are becoming increasingly important sources of safety and health concerns. Drinking water safety, which is closely related to human health, should receive more attention than natural water body safety. However, minimal research has been performed on the efficacy of existing treatment processes in water treatment plants for the removal of antibiotics and antibiotic resistance genes. To address this research gap, this study detected and analyzed six main antibiotics and nine antibiotic resistance genes in the treatment processes of two drinking water plants in Wuhan. Samples were collected over three months and then detected and analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry and fluorescence quantitation. The total concentrations of antibiotics and antibiotic resistance genes in the influent water of the two water plants were characterized as December > March > June. The precipitation and filtration processes of the Zou Maling Water Plant and Yu Shidun Water Plant successfully removed the antibiotics. The ozone-activated carbon process increased the removal rate of most antibiotics to 100%. However, a large amount of antibiotic resistance gene residues remained in the effluents of the two water plants. The experiments demonstrated that the existing ozone-activated carbon processes could not effectively remove antibiotic resistance genes. This study provides a reference for the optimization of drinking water treatment processes for antibiotics and antibiotic resistance gene removal.

Catalytic ozonation is a potential technology to eliminate refractory organic contaminants with the low concentration in secondary effluent from industrial park wastewater treatment plants (IPWWTPs). In this study, the catalytic ozonation over the Mn-based catalyst significantly improved the chemical oxygen demand (COD), total organic carbon (TOC), and UV₂₅₄ removals of secondary effluent from IPWWTPs. The Mn-based catalyst/O₃ system achieved 84.8%, 69.8%, and 86.4% removals of COD, TOC, and UV₂₅₄, which were 3.3, 5.7, and 1.1 times that in ozonation alone, respectively. Moreover, the Mn-based catalytic ozonation process exhibited excellent pH tolerance ranging from pH 4.0 to 9.0. Additionally, the depth analysis based on fluorescence excitation-emission matrix (EEM) confirmed that the catalytic ozonation process preferred to degrade toxic aromatic hydrocarbons. The existence of the Mn-based catalyst/O₃ system enhanced 21.4%–38.3% more fluorescent organic matters removal, compared to that in ozonation alone. Mechanistic studies proved that the abundant Lewis acid sites (Mnⁿ⁺/Mn⁽ⁿ⁺¹⁾⁺ and adsorbed oxygen) on the surface of the Mn-based catalyst effectively promoted O₃ decomposition into reactive oxygen species (ROS), and ·O₂⁻/HO₂· and ¹O₂ were the main ROS for degrading refractory organic contaminants. The contributions of ROS oxidation (91.2%) was much higher than that of direct O₃ oxidation (8.8%). Thus, this work provides an effective advanced treatment process for purifying secondary effluent from IPWWTPs.

Photocatalytic membranes offer an effective strategy to overcome the difficulties of solid-liquid separation and secondary contamination of powdered photocatalysts. MXene is a 2D material of layered Ti₃C₂, which is considered to limit electron-hole separation and contribute to photocatalysis. In this work, the etched Ti₃C₂ MXene was loaded on the surface of ceramic membranes using polydopamine (PDA) as a binder, followed by one-step calcination to produce TiO₂ nanoparticles (NPs) in situ. The characterizations supported that the TiO₂/Ti₃C₂ ceramic membranes had high mechanical strength while retaining the layered structure of Ti₃C₂, which was conducive to the inhibition of electron and hole complexation, improving the photocatalytic performance. Degradation experiments revealed that the material showed enhanced degradation of pharmaceuticals and personal care products (PPCPs) such as ciprofloxacin (CIP), tetracycline (TCN) and ibuprofen (IBP). The LC-MS and toxicity prediction models indicated that the developmental toxicity of CIP degradation products decreased with prolonged photocatalytic reaction, exhibiting no acute toxicity to fish. The MT650 exhibited significantly enhanced water flux properties (320 L/(m²·h)). The TiO₂/Ti₃C₂ ceramic membranes explored in this work are expected to target the treatment of PPCPs with excellent engineering promise.

Sewer networks play a vital role in sewage collection and transportation, and they are being rapidly expanded. However, the microbial processes occurring within these networks have emerged as significant contributors to greenhouse gas (GHG) emissions. Compared to that from other sectors, our understanding of the magnitude of GHG emissions from sewer networks is currently limited. In this study, we conducted a GHG emission assessment in an independent sewer network located in Beijing, China. The findings revealed annual emissions of 62.3 kg CH₄ and 0.753 kg N₂O. CH₄ emerged as the primary GHG emitted from sewers, accounting for 87.4% of the total GHG emissions. Interestingly, compared with main pipes, branch pipes were responsible for a larger share of GHG emissions, contributing to 76.7% of the total. A GHG emission factor of 0.26 kg CO₂-eq/(m·yr) was established to quantify sewer GHG emissions. By examining the isotopic signatures of CO₂/CH₄ pairs, it was determined that CH₄ production in sewers primarily occurred through acetate fermentation. Additionally, the structure of sewer pipes had a significant impact on GHG levels. This study offers valuable insights into the overall GHG emissions associated with sewer networks and sheds light on the mechanisms driving these emissions.