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1.
J Environ Manage ; 351: 119784, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38081091

RESUMEN

During the long-term stabilization process of landfills, the pressure field undergoes constant changes. This study constructed dynamic pressure changes scenarios of high-pressure differentials (0.6 MPa) and low-pressure differentials (0.2 MPa) in the landfill pressure field at 25 °C and 50 °C, and investigated the sulfate reduction behavior in response to landfill dynamic pressure changes. The results showed that the pressurization or depressurization of high-pressure differentials caused more significant differences in sulfate reduction behavior than that of low-pressure differentials. The lowest hydrogen sulfide (H2S) release peak concentration under pressurization was only 29.67% of that under initial pressure condition; under depressurization, the highest peak concentration of H2S was up to 21,828 mg m-3, posing a serious risk of H2S pollution. Microbial community and correlation analysis showed that pressure had a negative impact on the sulfate-reducing bacteria (SRB) community, and the SRB community adjusted its structure to adapt to pressure changes. Specific SRBs were further enriched with pressure changes. Differential H2S release behavior under pressure changes in the 25 °C pressure environments were mediated by Desulfofarcimen (ASV343) and Desulfosporosinus (ASV1336), while Candidatus Desulforudis (ASV24) and Desulfohalotomaculum (ASV94) played a key role at 50 °C. This study is helpful in the formulation of control strategies for the source of odor pollution in landfills.


Asunto(s)
Desulfovibrio , Sulfuro de Hidrógeno , Sulfuro de Hidrógeno/química , Instalaciones de Eliminación de Residuos , Sulfatos/química
2.
J Environ Manage ; 366: 121865, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39018858

RESUMEN

Landfill leachate is an important source of microplastics (MPs) and antibiotic-resistance genes (ARGs). Here, in the presence of polystyrene MPs (PS-MPs) and polyethylene MPs (PE-MPs), the nitrogen and phosphorus removal effect and sludge structure performance were affected in an anaerobic-anoxic-aerobic system, a typical biological leachate treatment process. The abundance of tetracycline-resistance genes (tet genes) in biofilms on the two types of MP was significantly higher than that in the leachate and sludge, and the load on PE-MPs was higher than that on PS-MPs because of the porous structure of PE-MPs. Aging of the MPs increased their surface roughness and abundance of oxygen-containing functional groups and shaped the profile of ARGs in the MP biofilms. The biofilm biomass and growth rate on the two types of MP increased with the incubation time in the first 30 days, and was affected by environmental factors. Structural equation models and co-occurrence network analysis demonstrated that the MPs indirectly affected the spectrum of ARGs by affecting biofilm formation, and, to a lesser extent, had a direct impact on the selective enrichment of ARGs. We discuss the mechanisms of the relationships between MPs and ARGs in the leachate treatment system, which will have guiding significance for future research. Our data on the colonization of microorganisms and tet genes in MPs biofilms provide new evidence concerning the accumulation and transmission of these ARGs, and are important for understanding the mechanisms of MPs in spreading pollution.


Asunto(s)
Biopelículas , Microplásticos , Resistencia a la Tetraciclina , Microplásticos/toxicidad , Biopelículas/efectos de los fármacos , Resistencia a la Tetraciclina/genética , Contaminantes Químicos del Agua/toxicidad , Bacterias/genética , Bacterias/efectos de los fármacos , Aguas del Alcantarillado/microbiología , Genes Bacterianos , Tetraciclina/farmacología
3.
Ecotoxicol Environ Saf ; 242: 113919, 2022 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-35901592

RESUMEN

The vertical distribution of sulfonamides (SAs), tetracyclines (TCs), macrolides (MLs), and their related antibiotic resistance genes (ARGs) were comprehensively investigated and characterized in a representative municipal solid waste (MSW) landfill in China. The total concentrations of target antibiotics in the MSW landfill were SAs > TCs > MLs. The abundances of mexF (10.78 ± 0.65 log10copies/g) and sul genes (9.15 ± 0.54 log10copies/g) were relatively high, while the tet genes (7.19 ± 0.77 log10copies/g) were the lowest. Both the abundance of antibiotics and genes fluctuated with landfill depth, and the ARGs of the same antibiotics were consistent with depth change. Intl1 and sul genes (sul1, sul2) were tightly connected, and a close relationship also existed between tet genes (tetM, tetQ) and MLs resistance genes (ermB, mefA). High-throughput sequencing showed the dominant genera were Sporosarcina (38%) and Thiobacillus (17%) at sampling points A and C, while the microbial community varied with depth increase at point B were Brevundimonas (20%), Sporosarcina (20%), Pseudomonas (24%), Lysobacter (28%), and Thioalkalimicrobium (14%), respectively. Network analysis further visualized the relationship among antibiotics, genes, and microbial communities and the results indicated the non-random connection among them and the possible host of the target gene. Even at 12.0 m below the landfill surface, the pollution of antibiotics resistance was still serious, which posed difficulties for subsequent landfill remediation and pollution control.


Asunto(s)
Antibacterianos , Residuos Sólidos , Antibacterianos/análisis , Antibacterianos/farmacología , China , Farmacorresistencia Microbiana/genética , Genes Bacterianos , Macrólidos , Residuos Sólidos/análisis , Tetraciclinas/análisis , Instalaciones de Eliminación de Residuos
4.
Ecotoxicol Environ Saf ; 222: 112532, 2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-34280839

RESUMEN

The effects of hydraulic condition of reactor and the dominant degrading bacteria on the removal of di-n-butyl phthalate (DBP) from aged landfill leachate by anaerobic/anoxic/oxic (A/A/O) leachate treatment process were investigated. The optimal DBP removal (96.0%) was obtained from aged leachate when the hydraulic retention time (HRT) of the reactor was 3 d, internal reflux ratio of the reactor was 200%, and external reflux ratio of the reactor was 60%, respectively. The removal efficiency of DBP was significantly improved after the inoculation of the dominant DBP-degrading bacteria (Pseudomonas sp. W1) in the reactor. The mean removal efficiencies of DBP before and after inoculation were 94.1% and 97.7%, respectively. Furthermore, the inoculation of dominant DBP-degrading bacteria changed the original sludge structure and characteristics, which was more conducive to the removal of DBP. These results provide theoretical basis for the effective removal of DBP from aged leachate by the biological treatment process.


Asunto(s)
Dibutil Ftalato , Contaminantes Químicos del Agua , Bacterias , Reactores Biológicos , Aguas del Alcantarillado
5.
Neuroimage ; 222: 117198, 2020 11 15.
Artículo en Inglés | MEDLINE | ID: mdl-32730957

RESUMEN

The diffusion MRI signal arising from neurons can be numerically simulated by solving the Bloch-Torrey partial differential equation. In this paper we present the Neuron Module that we implemented within the Matlab-based diffusion MRI simulation toolbox SpinDoctor. SpinDoctor uses finite element discretization and adaptive time integration to solve the Bloch-Torrey partial differential equation for general diffusion-encoding sequences, at multiple b-values and in multiple diffusion directions. In order to facilitate the diffusion MRI simulation of realistic neurons by the research community, we constructed finite element meshes for a group of 36 pyramidal neurons and a group of 29 spindle neurons whose morphological descriptions were found in the publicly available neuron repository NeuroMorpho.Org. These finite elements meshes range from having 15,163 nodes to 622,553 nodes. We also broke the neurons into the soma and dendrite branches and created finite elements meshes for these cell components. Through the Neuron Module, these neuron and cell components finite element meshes can be seamlessly coupled with the functionalities of SpinDoctor to provide the diffusion MRI signal attributable to spins inside neurons. We make these meshes and the source code of the Neuron Module available to the public as an open-source package. To illustrate some potential uses of the Neuron Module, we show numerical examples of the simulated diffusion MRI signals in multiple diffusion directions from whole neurons as well as from the soma and dendrite branches, and include a comparison of the high b-value behavior between dendrite branches and whole neurons. In addition, we demonstrate that the neuron meshes can be used to perform Monte-Carlo diffusion MRI simulations as well. We show that at equivalent accuracy, if only one gradient direction needs to be simulated, SpinDoctor is faster than a GPU implementation of Monte-Carlo, but if many gradient directions need to be simulated, there is a break-even point when the GPU implementation of Monte-Carlo becomes faster than SpinDoctor. Furthermore, we numerically compute the eigenfunctions and the eigenvalues of the Bloch-Torrey and the Laplace operators on the neuron geometries using a finite elements discretization, in order to give guidance in the choice of the space and time discretization parameters for both finite elements and Monte-Carlo approaches. Finally, we perform a statistical study on the set of 65 neurons to test some candidate biomakers that can potentially indicate the soma size. This preliminary study exemplifies the possible research that can be conducted using the Neuron Module.


Asunto(s)
Simulación por Computador , Imagen de Difusión por Resonancia Magnética , Procesamiento de Imagen Asistido por Computador/métodos , Modelos Teóricos , Neocórtex/citología , Neocórtex/diagnóstico por imagen , Neuroimagen , Neuronas , Imagen de Difusión por Resonancia Magnética/métodos , Humanos , Método de Montecarlo , Neuroimagen/métodos , Células Piramidales , Programas Informáticos
6.
Ecotoxicol Environ Saf ; 198: 110665, 2020 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-32353604

RESUMEN

Due to the wide use of plastic products and the releasability of plasticizer into surrounding environment, the hazards, residues and effects of phthalic acid esters (PAEs) in ecosystems have been paid more and more attention. Little information is available about the effects of PAEs on the normal wastewater treatment, although the distribution of PAEs in soil and other ecosystems is closely related to the discharge of sewage. In this study, the effects of high concentrations of di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) on pollutant removal and the microbial community during landfill leachate treatment was investigated. After domestication, the activated sludge was used in the co-treatment of landfill leachate and simulated domestic wastewater. We verified that this process reduced the toxicity of landfill leachate. However, high concentrations of added DBP and DEHP were removed first, while the removal of these pollutants from raw landfill leachate was limited. The results of high-throughput sequencing revealed that the bacterial diversity was diminished and the microbial community structure was significantly affected by the addition of DBP and DEHP. The DBP and DEHP samples had 79.05% and 82.25% operational taxonomic units (OTU), respectively, in common with the raw activated sludge. Many genera of PAE-degrading bacteria that had no significant evolutionary relationship were found in the raw activated sludge. And the widespread presence of PAE-degrading bacteria could effectively keep the concentrations of PAEs low during the wastewater treatment.


Asunto(s)
Dibutil Ftalato/toxicidad , Dietilhexil Ftalato/toxicidad , Microbiota/efectos de los fármacos , Eliminación de Residuos Líquidos/métodos , Contaminantes del Agua/toxicidad , Dibutil Ftalato/química , Ésteres/química , Ácidos Ftálicos , Plastificantes , Plásticos , Aguas del Alcantarillado/química , Suelo/química , Contaminantes del Suelo/análisis , Aguas Residuales , Contaminantes Químicos del Agua , Purificación del Agua
7.
Bull Environ Contam Toxicol ; 105(1): 36-40, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32472213

RESUMEN

The concentrations and distributions of five sulfonamide, three tetracycline, and two macrolide antibiotics in leachates from three landfill sites in northern Zhejiang Province, China, were determined by solid-phase extraction and ultra-high performance liquid chromatography mass spectrometry. Most of the antibiotics were detected in the leachate samples. The concentrations and distributions of the antibiotics in leachates of different ages were very different. The total sulfonamide, tetracycline, and macrolide concentrations in the leachates ranged from not detected to 1.57 × 103, not detected to 5.19 × 103, and 7.30 to 5.42 × 102 ng/L, respectively. The total concentrations of detectable antibiotics were higher in fresh leachates than aged and middle-aged leachates. Higher TC-group concentrations were found in the leachates than have been found in previously published studies of landfill leachates in China. The results improve our understanding of and ability to manage antibiotic residues in landfills.


Asunto(s)
Antibacterianos/análisis , Monitoreo del Ambiente , Contaminantes Químicos del Agua/análisis , China , Eliminación de Residuos , Extracción en Fase Sólida , Instalaciones de Eliminación de Residuos
8.
Biodegradation ; 28(5-6): 327-335, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-28674758

RESUMEN

Municipal solid waste landfills are responsible for odors affecting the environment and human health. Dimethyl sulfide (DMS) is one of the major odorous compounds known for its low odor threshold and wide distribution. This study examined the generation, migration and emission of DMS in four artificial landfill-simulating reactors: Reactor 1 and Reactor 2, running under anaerobic and semi-aerobic conditions, respectively, without leachate recirculation; and Reactor 3 and Reactor 4, running under anaerobic and semi-aerobic conditions, respectively, with leachate recirculation. From the odor control perspective, aeration can efficiently inhibit maximum DMS headspace concentration by 31.7-93.7%, especially with the functioning of leachate recirculation. However, leachate recirculation in anaerobic conditions may double the DMS emission concentration but may also shorten the period over which DMS is effective because of the upward migration of liquid DMS in the recirculated leachate. The DMS generation was active in the acidification and methane fermentation phase of the simulated landfill and was possibly affected by the volatile fatty acid concentration, chemical oxygen demand, total organic carbon concentration and pH of the leachate, as well as total organic carbon in the refuse. Most significantly, DMS emission can be effectually dealt with by aeration along with leachate recirculation.


Asunto(s)
Contaminantes Atmosféricos/química , Sulfuros/química , Contaminantes Químicos del Agua/química , Análisis de la Demanda Biológica de Oxígeno , Monitoreo del Ambiente , Ácidos Grasos Volátiles/análisis , Metano/análisis , Instalaciones de Eliminación de Residuos , Agua/química
9.
Bull Environ Contam Toxicol ; 98(4): 472-477, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28239739

RESUMEN

The occurrence and distribution of five sulfonamides and three tetracyclines in swine manure sampled from large-scale feedlots in different areas of Zhejiang Province, China were detected using solid-phase extraction and high-performance liquid chromatography. All eight test antibiotics were detected in most of the manure samples. The dominant antibiotics in swine manure were sulfadiazine, sulfamerazine, sulfadimidine, tetracycline, and chlortetracycline. The maximum concentration of residual antibiotic reached up to 57.95 mg/kg (chlortetracycline). The concentrations and distribution of both types of antibiotics in swine manure of different areas varied greatly. Relatively higher concentrations of sulfonamides were found in swine manure from the Zhejiang area in this experiment compared with previous studies. The results revealed that antibiotics were extensively used in feedlots in this district and that animal manure might act as a non-specific source of antibiotic residues in farmlands and aquatic environments.


Asunto(s)
Estiércol/análisis , Sulfonamidas/análisis , Tetraciclinas/análisis , Animales , Antibacterianos/análisis , China , Cromatografía Líquida de Alta Presión , Extracción en Fase Sólida , Porcinos
10.
J Environ Manage ; 154: 159-65, 2015 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-25725388

RESUMEN

Hydrogen sulfide (H2S(g)) emission from landfills is a widespread problem, especially when aged refuse is excavated. H2S(g) emission from aged refuse exposed to air was investigated and the results showed that large amounts of H2S(g) can be released, especially in the first few hours after excavation, when H2S(g) concentrations in air near refuse could reach 2.00 mg m(-3). Initial exposure to air did not inhibit the emission of H2S(g), as is generally assumed, but actually promoted it. The amounts of H2S(g) emitted in the first 2 d after excavation can be very dangerous, and the risks associated with the emission of H2S(g) could decrease significantly with time. Unlike a large number of sulfide existed under anaerobic conditions, the sulfide in aged municipal solid waste can be oxidized chemically to elemental sulfur (but not sulfate) under aerobic conditions, and its conversion rate was higher than 80%. Only microorganisms can oxidize the reduced sulfur species to sulfate, and the conversion rate could reach about 50%. Using appropriate techniques to enhance these chemical and biological transformations could allow the potential health risks caused by H2S(g) after refuse excavation to be largely avoided.


Asunto(s)
Contaminantes Atmosféricos/química , Contaminación del Aire/prevención & control , Sulfuro de Hidrógeno/química , Instalaciones de Eliminación de Residuos , Residuos , Monitoreo del Ambiente , Humanos
11.
Bioresour Technol ; 406: 130971, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38897156

RESUMEN

Microorganisms harvest energy from agricultural waste by degrading its structure. By comparing with Trichoderma reesei QM6a in cellulase production, straw deconstruction and transcriptome response, Trichoderma asperellum T-1 was identified to be prioritized for the fermentation of natural straw. Cellulase activity of T-1 was 50%-102% higher than QM6a. And the degradation rate of hemicellulose and ligin in wheat straw by T-1 reached 40% and 42%. Time-driven changes in the gene expression of extracellular proteins involved in polysaccharide, xylan, and hemicellulose metabolism and hydrolysis indicated that T-1 positively responded in both solid state fermentation and submerged fermentation for lignocellulose degradation. A significantly enriched category encoding carbohydrate-binding modules is considered critical for the deconstruction of the natural structure by T-1. The findings highlight the superiority of T. asperellum T-1 in straw fermentation, base on which, the construction of efficient microbial agents is expected to enhance the utilization of biomass.


Asunto(s)
Fermentación , Triticum , Triticum/metabolismo , Hidrólisis , Lignina/metabolismo , Hypocreales/metabolismo , Hypocreales/genética , Regulación Fúngica de la Expresión Génica , Transcripción Genética , Celulasa/metabolismo
12.
Phys Med Biol ; 68(17)2023 08 29.
Artículo en Inglés | MEDLINE | ID: mdl-37579758

RESUMEN

Objective. The complex-valued transverse magnetization due to diffusion-encoding magnetic field gradients acting on a permeable medium can be modeled by the Bloch-Torrey partial differential equation. The diffusion magnetic resonance imaging (MRI) signal has a representation in the basis of the Laplace eigenfunctions of the medium. However, in order to estimate the permeability coefficient from diffusion MRI data, it is desirable that the forward solution can be calculated efficiently for many values of permeability.Approach. In this paper we propose a new formulation of the permeable diffusion MRI signal representation in the basis of the Laplace eigenfunctions of the same medium where the interfaces are made impermeable.Main results.We proved the theoretical equivalence between our new formulation and the original formulation in the case that the full eigendecomposition is used. We validated our method numerically and showed promising numerical results when a partial eigendecomposition is used. Two diffusion MRI sequences were used to illustrate the numerical validity of our new method.Significance.Our approach means that the same basis (the impermeable set) can be used for all permeability values, which reduces the computational time significantly, enabling the study of the effects of the permeability coefficient on the diffusion MRI signal in the future.


Asunto(s)
Algoritmos , Imagen de Difusión por Resonancia Magnética , Imagen de Difusión por Resonancia Magnética/métodos , Difusión
13.
Med Image Anal ; 90: 102979, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37827109

RESUMEN

We propose a framework to train supervised learning models on synthetic data to estimate brain microstructure parameters using diffusion magnetic resonance imaging (dMRI). Although further validation is necessary, the proposed framework aims to seamlessly incorporate realistic simulations into dMRI microstructure estimation. Synthetic data were generated from over 1,000 neuron meshes converted from digital neuronal reconstructions and linked to their neuroanatomical parameters (such as soma volume and neurite length) using an optimized diffusion MRI simulator that produces intracellular dMRI signals from the solution of the Bloch-Torrey partial differential equation. By combining random subsets of simulated neuron signals with a free diffusion compartment signal, we constructed a synthetic dataset containing dMRI signals and 40 tissue microstructure parameters of 1.45 million artificial brain voxels. To implement supervised learning models we chose multilayer perceptrons (MLPs) and trained them on a subset of the synthetic dataset to estimate some microstructure parameters, namely, the volume fractions of soma, neurites, and the free diffusion compartment, as well as the area fractions of soma and neurites. The trained MLPs perform satisfactorily on the synthetic test sets and give promising in-vivo parameter maps on the MGH Connectome Diffusion Microstructure Dataset (CDMD). Most importantly, the estimated volume fractions showed low dependence on the diffusion time, the diffusion time independence of the estimated parameters being a desired property of quantitative microstructure imaging. The synthetic dataset we generated will be valuable for the validation of models that map between the dMRI signals and microstructure parameters. The surface meshes and microstructures parameters of the aforementioned neurons have been made publicly available.


Asunto(s)
Encéfalo , Conectoma , Humanos , Simulación por Computador , Encéfalo/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética/métodos , Conectoma/métodos , Aprendizaje Automático Supervisado , Procesamiento de Imagen Asistido por Computador/métodos
14.
Environ Technol ; 44(16): 2407-2416, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35029135

RESUMEN

The effect of hydraulic parameters of an anaerobic/anoxic/oxic leachate treatment reactor on the removal of di(2-ethylhexyl) phthalate (DEHP) from aged landfill leachate was studied. The mean DEHP removal efficiencies were 79.5%, 87.1%, 89.7% and 87.8% at hydraulic retention times of 6, 4.5, 3 and 2 d, respectively. The removal efficiency of DEHP was significantly higher when the internal reflux ratio was 200% than others. There was no significant difference among the DEHP removal efficiencies at different external reflux ratios of the reactor. Due to the overall efficiency of the reactor, hydraulic retention time 3 d, internal reflux ratio 200% and external reflux ratio 60%, were considered the optimal hydraulic parameters for DEHP removal from aged leachate. The removal efficiency of DEHP was significantly improved (from 75.7% to 89.1%) after the optimization of hydraulic parameters of the reactor. The removal percentages of DEHP in the anaerobic, anoxic, and oxic units of the reactor were 42.8%, 17.6%, and 15.3%, respectively. The oxic microcosms in the reactor had little effect on DEHP removal. The correlation between DEHP and leachate pollutants indicated that DEHP removal was strongly correlated with leachate COD and NH4+-N.


Asunto(s)
Dietilhexil Ftalato , Ácidos Ftálicos , Contaminantes Químicos del Agua , Contaminantes Químicos del Agua/análisis , Reactores Biológicos
15.
Bioresour Technol ; 387: 129610, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37544547

RESUMEN

The study quantified the biological nitrogen removal performance, microbial metabolism, microbial community structure, and antioxidant system in a sequencing batch reactor under long-term exposure to 0.1 and 1 mg/L tire wear particles (TWPs), and determined the contribution of leachable additives to the biotoxicity of TWPs. The results showed that long-term exposure to 0.1 and 1 mg/L TWPs inhibited both the nitrification and denitrification processes, reducing ammonia nitrogen (NH4+-N) and total nitrogen (TN) removal efficiency. The TWP leachate (TWPL) primarily contributed to the denitrification inhibition by TWPs, potentially due to the high concentration of zinc ions in the leachable additive. Furthermore, both TWP and TWPL inhibit nitrogen conversion, with TWP inhibiting the generation and transfer of electrons, while TWPL only negatively affects the electron transfer process. This study presents novel insights into the impact of TWPs on biological nitrogen removal, underscoring its broader implications for the geochemical nitrogen cycle.


Asunto(s)
Desnitrificación , Aguas Residuales , Nitrógeno , Reactores Biológicos , Nitrificación
16.
Chemosphere ; 341: 140100, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37683946

RESUMEN

Microplastics (MPs) pollution is a pressing environmental issue for aquatic ecosystems. Landfill leachate is an important contributor of MPs and antibiotic resistant genes (ARGs). However, there are few studies on the colonization of ARGs and pathogens on MPs in leachate. This study conducted incubation experiments with polyethylene terephthalate (PET) and polypropylene (PP) MPs in landfill leachate which were about 3-5 years old (PL) and 5-10 years old (AL). After incubation, the bacterial cells colonized and grew on the surface of MPs, inducing the increase of oxygenated oxygen functional groups (e.g., hydroxyl, carbonyl) on the MPs surface. Real-time PCR indicated that MPs selectively enriched ARGs, such as genes tetM, tetC, mcr-1, aac(6')-Ib-cr, blaTEM and blaSHV in leachate. The diversity of bacterial communities on MPs was significantly increased in AL leachate, but decreased in PL leachate. The differences in bacterial communities in MPs biofilms were related to the type of MPs. Compared with AL leachate, the abundance of Chloroflexi increased by 15.7% on the PET, and the abundance of Acidobacteriota increased by 6.23 fold on the PP. The abundance of Firmicutes increased from 20.7% in PL leachate to 65.8% and 60.7% on PET and PP, respectively. Additionally, pathogens were observed to be more abundant on MPs compared to leachate. In particular, pathogens (Staphylococcus, Streptococcus, Enterobacter and Rhodococcus) associated with sul1 and sul2 were generally present at higher levels on MPs than in the surrounding leachate. These results provide significant implications for understanding the health risk of MPs in the environment.


Asunto(s)
Contaminantes Químicos del Agua , Contaminantes Químicos del Agua/toxicidad , Ecosistema , Microplásticos , Plásticos , Antibacterianos/farmacología , Farmacorresistencia Microbiana , Tereftalatos Polietilenos , Polipropilenos
17.
Waste Manag ; 171: 491-501, 2023 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-37806157

RESUMEN

The behavior of sulfate reduction, which was the source of hydrogen sulfide (H2S) odor, was investigated under changing pressure and temperature conditions inside landfills. The results showed that the release of H2S and methyl mercaptan (MM) was significantly inhibited at 25 °C and 50 °C under pressure, and the highest H2S and MM concentrations released were only 0.82 %-1.30 % and 1.87 %-4.32 % of atmospheric pressure, respectively. Analysis of the microbial community structure and identification of sulfate-reducing bacteria (SRB) revealed that temperature significantly altered the microbial community in the landfill environment, while pressure inhibited some bacteria and induced the growth and reproduction of specific bacteria. Key SRB (Desulfosporosinus-ASV212, Desulfitibacter-ASV1744) mediated differentiated sulfate reduction behavior in the pressure-bearing environment at 25 °C, while key SRB (Dethiobacter-ASV177, Desulfitibacter-ASV2355 and ASV316) were involved at 50 °C. This study provides a theoretical basis for the formulation of landfill gas management and control strategies.

18.
Bioresour Technol ; 379: 129001, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37011839

RESUMEN

Wastewater treatment plants can be nanoplastics (NPs) and microplastics (MPs) sinks and sources. The effects of NPs and MPs on nitrogen removal and extracellular polymeric substances (EPS) during activated sludge process need further investigation. Results showed that polystyrene NPs (NPS) and 100 mg/L polystyrene MPs (MPS) decreased the specific nitrate reduction rate, resulting in nitrate accumulation. The negative effects on functional genes involved in denitrification (narG, napA, nirS and nosZ) were the main mechanism. NPS stimulated EPS secretion, but MPS inhibited it. NPS and MPS increased the ratio of protein to polysaccharide except for 10 mg/L MPS and changed the secondary structure of protein in EPS, affecting flocculation ability of activated sludge. The changes of microbial abundance in activated sludge could be the main factor to the alterations of EPS and nitrogen removal. These results may facilitate understanding the impacts of NPs and MPs on wastewater treatment processes.


Asunto(s)
Microbiota , Aguas del Alcantarillado , Aguas del Alcantarillado/química , Microplásticos/análisis , Microplásticos/farmacología , Matriz Extracelular de Sustancias Poliméricas/química , Plásticos , Poliestirenos , Desnitrificación , Nitrógeno/análisis , Nitratos/farmacología , Reactores Biológicos , Eliminación de Residuos Líquidos
19.
Environ Pollut ; 333: 121981, 2023 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-37321316

RESUMEN

The environmental behavior of emerging contaminants of microplastics (MPs), antibiotics and antibiotic resistance genes (ARGs) in the leachate activated sludge system has been monitored and analyzed comprehensively. The results suggested that MPs could effectively alter the migration trajectory of tetracycline resistance genes (tet genes) in the leachate activated sludge system under intermittent and continuous influent conditions. After adding MPs, the total average abundance of tet genes in leachate increased from 0.74 ± 0.07 to 0.78 ± 0.07 (log10tet genes/log10 16S rRNA) and that in sludge increased from 0.65 ± 0.08 to 0.70 ± 0.06 (log10tet genes/log10 16S rRNA). Except for tetA, the abundance of tetB, tetO, tetM and tetQ on MPs increased with increasing TC concentration under both aerobic and anaerobic conditions. MPs not only significantly affect the abundance level and migration trajectory of ARGs in the leachate activated sludge system, but also remarkably improve the level of heavy metals in the ambient environment, indirectly promoting the selective effect of antibiotic-resistant bacteria (ARB) and promoting the development of antibiotic resistance (AR). In addition, MPs changed their physicochemical properties and released hazardous substances with aging to force tet genes to migrate from the leachate activated sludge system to the MPs, making AR more difficult to eliminate and persisted in wastewater treatment plants. Meanwhile, microorganisms played a driving role, making MPs serve as a niche for ARGs and ARB colonization. The co-occurrence network analysis indicated the specific distribution pattern of tet genes and microorganisms in different media, and the potential host was speculated. This study improves the understanding of the environmental behavior of emerging contaminants in leachate activated sludge system and lays a theoretical for protecting the ecological environment.


Asunto(s)
Microplásticos , Aguas del Alcantarillado , Aguas del Alcantarillado/microbiología , Plásticos , ARN Ribosómico 16S/genética , Antagonistas de Receptores de Angiotensina , Inhibidores de la Enzima Convertidora de Angiotensina , Genes Bacterianos , Antibacterianos/farmacología , Antibacterianos/análisis , Farmacorresistencia Microbiana/genética
20.
Environ Sci Pollut Res Int ; 30(39): 90844-90857, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37464207

RESUMEN

The mechanism of antibiotic resistance (AR) development in an activated sludge system under tetracycline (TC) pressure was discussed and analyzed. According to the variation of macro-factors, including TC, COD, TN, TP, NH3-N, pH, heavy metals, and reactor settings, the tet genes respond accordingly. Consequently, the enrichment sites of tet genes form an invisible AR selection zone, where AR microorganisms thrive, gather, reproduce, and spread. The efflux pump genes tetA and tetB prefer anaerobic environment, while ribosome protective protein genes tetM, tetO, tetQ, tetT, and tetW were more concentrated in aerobic situations. As a corresponding micro-effect, different types of tet genes selected the corresponding dominant bacteria such as Thauera and Arthrobacter, suggesting the intrinsic relationship between tet genes and potential hosts. In summary, the macro-response and micro-effect of tet genes constitute an interactive mechanism with tet genes as the core, which is the crucial cause for the continuous development of AR. This study provides an executable strategy to control the development of AR in actual wastewater treatment plants from the perspective of macro-factors and micro-effects.


Asunto(s)
Genes Bacterianos , Aguas del Alcantarillado , Aguas del Alcantarillado/microbiología , Antibacterianos/farmacología , Tetraciclina/farmacología , Farmacorresistencia Microbiana/genética , Resistencia a la Tetraciclina/genética
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