Journal of environmental sciences最新文献

Developing industrially moldable catalysts with harmonized redox performance and acidity is of great significance for the efficient disposal of chlorinated volatile organic compounds (CVOCs) in actual exhaust gasses. Here, commercial TiO₂, typically used for molding catalysts, was chosen as the carrier to fabricate a series of Ce_0.02Mn_0–0.24TiO_x materials with different Mn doping ratios and employed for chlorobenzene (CB) destruction. The introduction of Mn remarkedly facilitated the synergistic effect of each element via the electron transfer processes: Ce³⁺+Mn^4+/3+↔Ce⁴⁺+Mn^3+/2+ and Mn^4+/3++Ti⁴⁺↔Mn^3+/2++Ti³⁺. These synergistic interactions in Ce_0.02Mn_0.04–0.24TiO_x, especially Ce_0.02Mn_0.16TiO_x, significantly elevated the active oxygen species, oxygen vacancies and redox properties, endowing the superior catalytic oxidation of CB. When the Mn doping amount increased to 0.24, a separate Mn₃O₄ phase appeared, which in turn might weaken the synergistic effect. Furthermore, the acidity of Ce_0.02Mn_0.04–0.24TiO_x was decreased with the Mn doping, regulating the balance of redox property and acidity. Notably, Ce_0.02Mn_0.16TiO_x featured relatively abundant B-acid sites. Its coordinating redox ability and moderate acidity promoted the deep oxidation of CB and RCOOH- intermediates, as well as the rapid desorption of Cl species, thus obtaining sustainable reactivity. In comparison, CeTiO_x owned the strongest acidity, however, its poor redox property was not sufficient for the timely oxidative decomposition of the easier adsorbed CB, resulting in its rapid deactivation. This finding provides a promising strategy for the construction of efficient commercial molding catalysts to decompose the industrial-scale CVOCs.

Effective monitoring and management of microbial risk factors in wastewater treatment plants (WWTPs) effluents require a comprehensive investigation of these risks. A global survey on microbial risk factors in WWTP effluents could reveal important insights into their risk features. This study aims to explore the abundance and types of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), the vector of ARG/VFG, and dominant pathogens in global WWTP effluents. We collected 113 metagenomes of WWTP effluents from the Sequence Read Archive of the National Center for Biotechnology Information and characterized the microbial risk factors. Our results showed that multidrug resistance was the dominant ARG type, while offensive virulence factors were the most abundant type of VFGs. The most dominant types of ARGs in the vector of plasmid and phage were both aminoglycoside resistance, which is concerning as aminoglycosides are often a last resort for treating multi-resistant infections. Acinetobacter baumannii was the most dominant pathogen, rather than Escherichia coli, and a weak negative correlation between Escherichia coli and two other dominant pathogens (Acinetobacter baumannii and Bacteroides uniformis) suggests that using Escherichia coli as a biological indicator for all pathogens in WWTP effluents may not be appropriate. The Getah virus was the most dominant virus found in global WWTP effluents. Our study presents a comprehensive global-scale investigation of microbial risk factors in WWTP effluents, providing valuable insights into the potential risks associated with WWTP effluents and contributing to the monitoring and control of these risks.

Low desulfurization efficiency impedes the wide application of dry desulfurization technology, which is a low-cost and simple process, and one significant solution is the development and manufacture of high-performance desulfurizers. In this study, firstly, a steam jet mill was used to digest quicklime; then, we utilized numerical simulation to study the flow field distribution and analyze the driving factors of quicklime digestion; and lastly, the desulfurization performance of the desulfurizer was evaluated under different relative humidities. The results show that the desulfurizer prepared via the steam jet mill had better apparent activity than traditional desulfurizers. Also, the entire jet flow field of the steam jet mill is in a supersonic and highly turbulent flow state, with high crushing intensity and good particle acceleration performance. Sufficient contact with the nascent surface maximizes the formation of slaked lime. The experiments demonstrated that the operating time with 100% desulfurization efficiency and the “break-through” time for the desulfurizer prepared via the steam jet mill is longer than that of traditional desulfurizers, and has significant advantages, especially at low flue gas relative humidity. Compared with traditional desulfurizers, the desulfurizer prepared via steam jet mill expands the range of acceptable flue gas temperature, and the failure temperature is 1.625 times that of traditional desulfurizers. This work breaks through the technical bottleneck of low dry desulfurization efficiency, which is an important step in pushing forward the application of dry desulfurization.

Membrane distillation (MD) is a promising alternative desalination technology, but the hydrophobic membrane cannot intercept volatile organic compounds (VOCs), resulting in aggravation in the quality of permeate. In term of this, electro-Fenton (EF) was coupled with sweeping gas membrane distillation (SGMD) in a more efficient way to construct an advanced oxidation barrier at the gas-liquid interface, so that the VOCs could be trapped in this layer to guarantee the water quality of the distillate. During the so-called EF-MD process, an interfacial interception barrier containing hydroxyl radical formed on the hydrophobic membrane surface. It contributed to the high phenol rejection of 90.2% with the permeate phenol concentration lower than 1.50 mg/L. Effective interceptions can be achieved in a wide temperature range, even though the permeate flux of phenol was also intensified. The EF-MD system was robust to high salinity and could electrochemically regenerate ferrous ions, which endowed the long-term stability of the system. This novel EF-MD configuration proposed a valuable strategy to intercept VOCs in MD and will broaden the application of MD in hypersaline wastewater treatment.

Zhuzhou was one of the most polluted cities in China with the serious acid rain. Due to the implementation of air pollution control measures from 2016 to 2018, the acid rain pollution in this city has reduced. In order to understand the recent situation, a comprehensive study on the acid rain was carried out from January 2011 to December 2020. The pH values during the study period varied from 3.3 to 7.5, with a volume-weighted mean value of 4.7. The predominant acidic components of the precipitation were SO₄²⁻ and NO₃⁻, accounting for 89.3% of the total anions. The ratio of non-sea-salt SO₄²⁻ to NO₃⁻ showed a decreasing trend, revealing that the pollution type of acid rain changed from sulfuric acid type to sulfuric acid and nitric acid compound type. The correlation analysis (p < 0.05) showed that SO₄²⁻ was positively correlated with NH₄⁺, Ca²⁺, and Mg²⁺; hence, it predominated in precipitation as (NH₄)₂SO₄, NH₄HSO₄, CaSO₄, and MgSO₄. Significant positive correlation of Ca²⁺ with Mg²⁺ shows that they may originated mainly from crust. Significant positive correlation between SO₄²⁻ and F⁻ and Cl⁻ indicate that their source may be related to the non-ferrous metal smelting industry in Zhuzhou. Further correlation analysis shows that emissions from the non-ferrous metal smelting industry in the area have a large significant on SO₄²⁻ and F⁻ in precipitation, while Cl⁻ may still be emitted from other anthropogenic sources.

It is particularly important to comprehensively assess the biotoxicity variation of industrial wastewater along the treatment process for ensuring the water environment security. However, intensive studies on the biotoxicity reduction of industrial wastewater are still limited. In this study, the toxic organics removal and biotoxicity reduction of coal chemical wastewater (CCW) along a novel full-scale treatment process based on the pretreatment process-anaerobic process-biological enhanced (BE) process-anoxic/oxic (A/O) process-advanced treatment process was evaluated. This process performed great removal efficiency of COD, total phenol, NH₄⁺-N and total nitrogen. And the biotoxicity variation along the treatment units was analyzed from the perspective of acute biotoxicity, genotixicity and oxidative damage. The results indicated that the effluent of pretreatment process presented relatively high acute biotoxicity to Tetrahymena thermophila. But the acute biotoxicity was significantly reduced in BE-A/O process. And the genotoxicity and oxidative damage to Tetrahymena thermophila were significantly decreased after advanced treatment. The polar organics in CCW were identified as the main biotoxicity contributors. Phenols were positively correlated with acute biotoxicity, while the nitrogenous heterocyclic compounds and polycyclic aromatic hydrocarbons were positively correlated with genotoxicity. Although the biotoxicity was effectively reduced in the novel full-scale treatment process, the effluent still performed potential biotoxicity, which need to be further explored in order to reduce environmental risk.

Previous air pollution control strategies didn't pay enough attention to regional collaboration and the spatial response sensitivities, resulting in limited control effects in China. This study proposed an effective PM_2.5 and O₃ control strategy scheme with the integration of Self-Organizing Map (SOM), Genetic Algorithm (GA) and WRF-CAMx, emphasizing regional collaborative control and the strengthening of control in sensitive areas. This scheme embodies the idea of hierarchical management and spatial-temporally differentiated management, with SOM identifying the collaborative subregions, GA providing the optimized subregion-level priority of precursor emission reductions, and WRF-CAMx providing response sensitivities for grid-level priority of precursor emission reductions. With Beijing-Tianjin-Hebei and the surrounding area (BTHSA, “2 + 26” cities) as the case study area, the optimized strategy required that regions along Taihang Mountains strengthen the emission reductions of all precursors in PM_2.5-dominant seasons, and strengthen VOCs reductions but moderate NOx reductions in O₃-dominant season. The spatiotemporally differentiated control strategy, without additional emission reduction burdens than the 14th Five-Year Plan proposed, reduced the average annual PM_2.5 and MDA8 O₃ concentrations in 28 cities by 3.2%–8.2% and 3.9%–9.7% respectively in comparison with non-differential control strategies, with the most prominent optimization effects occurring in the heavily polluted seasons (6.9%–18.0% for PM_2.5 and 3.3%–14.2% for MDA8 O₃, respectively). This study proposed an effective scheme for the collaborative control of PM_2.5 and O₃ in BTHSA, and shows important methodological implications for other regions suffering from similar air quality problems.

The reaction of carbonyl-to-imine/hemiaminal conversion in the atmospheric aqueous phase is a critical pathway to produce the light-absorbing N-containing secondary organic compounds (SOC). The formation mechanism of these compounds has been wildly investigated in bulk solutions with a low ionic strength. However, the ionic strength in the aqueous phase of the polluted atmosphere may be higher. It is still unclear whether and to what extent the inorganic ions can affect the SOC formation. Here we prepared the bulk solution with certain ionic strength, in which glyoxal and ammonium were mixed to mimic the aqueous-phase reaction. Molecular characterization by High-resolution Mass Spectrometry was performed to identify the N-containing products, and the light absorption of the mixtures was measured by ultraviolet-visible spectroscopy. Thirty-nine N-containing compounds were identified and divided into four categories (N-heterocyclic chromophores, high-molecular-weight compounds with N-heterocycle, aliphatic imines/hemiaminals, and the unclassified). It was observed that the longer reaction time and higher ionic strength led to the formation of more N-heterocyclic chromophores and the increasing of the light-absorbance of the mixture. The added inorganic ions were proposed to make the aqueous phase somewhat viscous so that the molecules were prone to undergo consecutive and intramolecular reactions to form the heterocycles. In general, this study revealed that the enhanced ionic strength and prolonged reaction time had the promotion effect on the light-absorbing SOC formation. It implies that the aldehyde-derived aqueous-phase SOC would contribute more light-absorbing particulate matter in the industrial or populated area where inorganic ions are abundant.

Environmental effects of nano remediation engineering of arsenic (As) pollution need to be considered. In this study, the roles of Fe₂O₃ and TiO₂ nanoparticles (NPs) on the microbial mediated As mobilization from As contaminated soil were investigated. The addition of Fe₂O₃ and TiO₂ NPs restrained As(V) release, and stimulated As(III) release. As(V) concentration decreased by 94% and 93% after Fe₂O₃ addition, and decreased by 89% and 45% after TiO₂ addition compared to the Biotic and Biotic+Acetate (amended with sodium acetate) controls, respectively. The maximum values of As(III) were 20.5 and 27.1 µg/L at 48 d after Fe₂O₃ and TiO₂ NPs addition, respectively, and were higher than that in Biotic+Acetate control (12.9 µg/L). The released As co-precipitated with Fe in soils in the presence of Fe₂O₃ NPs, but adsorbed on TiO₂ NPs in the presence of TiO₂ NPs. Moreover, the addition of NPs amended with sodium acetate as the electron donor clearly promoted As(V) reduction induced by microbes. The NPs addition changed the relative abundance of soil bacterial community, while Proteobacteria (42.8%-70.4%), Planctomycetes (2.6%-14.3%), and Firmicutes (3.5%-25.4%) were the dominant microorganisms in soils. Several potential As/Fe reducing bacteria were related to Pseudomonas, Geobacter, Desulfuromonas, and Thiobacillus. The addition of Fe₂O₃ and TiO₂ NPs induced to the decrease of arrA gene. The results indicated that the addition of NPs had a negative impact on soil microbial population in a long term. The findings offer a relatively comprehensive assessment of Fe₂O₃ and TiO₂ NPs effects on As mobilization and soil bacterial communities.

Environmental photocatalysis is a promising technology for treating antibiotics in wastewater. In this study, a supercritical carbonization method was developed to synthesize a single-atom photocatalyst with a high loading of Ni (above 5 wt.%) anchored on a carbon-nitrogen-silicate substrate for the efficient photodegradation of a ubiquitous environmental contaminant of tetracycline (TC). The photocatalyst was prepared from an easily obtained metal-biopolymer-inorganic supramolecular hydrogel, followed by supercritical drying and carbonization treatment. The low-temperature (300°C) supercritical ethanol treatment prevents the excessive structural degradation of hydrogel and greatly reduces the metal clustering and aggregation, which contributed to the high Ni loading. Atomic characterizations confirmed that Ni was present at isolated sites and stabilized by Ni-N and Ni-O bonds in a Ni-(N/O)₆C/SiC configuration. A 5% Ni-C-Si catalyst, which performed the best among the studied catalysts, exhibited a wide visible light response with a narrow bandgap of 1.45 eV that could efficiently and repeatedly catalyze the oxidation of TC with a conversion rate of almost 100% within 40 min. The reactive species trapping experiments and electron spin resonance (ESR) tests demonstrated that the h⁺, and ·O₂⁻ were mainly responsible for TC degradation. The TC degradation mechanism and possible reaction pathways were provided also. Overall, this study proposed a novel strategy to synthesize a high metal loading single-atom photocatalyst that can efficiently remove TC with high concentrations, and this strategy might be extended for synthesis of other carbon-based single-atom catalysts with valuable properties.