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1.
Sci Total Environ ; 760: 143933, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33341639

RESUMO

Anaerobic digestion is an effective treatment technology for wastewater. However, long HRT and low CH4 production limit the application of anaerobic treatment. Iron-based materials, carbon-based materials and Fe-C composite particles have been used in anaerobic processes. However, the strengthening effect of Fe-C composite particles on anaerobic systems requires further research. In this study, granular activated carbon (GAC) loaded with nanoscale zero-valent iron (NZVI) was prepared by a co-precipitation method and its morphology was characterized. Different concentrations of GAC-NZVI particles were used in the batch experiment to study the enhancing effect of the anaerobic biological treatment process. The water quality, sludge properties and microbial community were analyzed. The degradation rate of COD and total CH4 production increased by 9.38% and 14.29% with particles at a concentration of 1000 mg/L, respectively. The average methane yield was 169.86 mL CH4/g-COD removed, which was 9.39% higher than that of the control. The measurement results of extracellular polymeric substance (EPS), conductivity, cyclic voltammetry (CV) and Fe concentration indicated that the composite particles showed excellent electrical conductivity and promoted microorganism metabolism, which accelerated the use of substrates and methane generation. The 3-dimensional excitation (Ex) - emission (Em) matrix (3D-EEM) fluorescence spectroscopy of soluble microbial product (SMP) and EPS indicated that the particles could affect the endogenous respiration of microorganisms. Microbial community analysis revealed that the dominant genus Methanothrix (acetoclastic methanogens) increased by 13.32%, which could strengthen acetoclastic methanogenesis and lead to higher CH4 production. The abundance of hydrogenotrophic archaea decreased after the addition of GAC-NZVI. These results provide an alternate method for enhancing anaerobic wastewater treatment using conductive particles.


Assuntos
Carvão Vegetal , Ferro , Anaerobiose , Reatores Biológicos , Matriz Extracelular de Substâncias Poliméricas , Metano , Esgotos , Água
2.
Chemosphere ; 268: 129363, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33360935

RESUMO

Magnetic seeding coagulation (MSC) process has been used to accelerate flocs sedimentation with an applied magnetic field, offering large handling capacity and low energy consumption. The interactions of three typical Al species, aluminum chloride (AlCl3), Al13O4(OH)247+ polymer (Al13), and (AlO4)2Al28(OH)5618+ polymer (Al30), with magnetic particles (MPs) were examined to clarify the MSC process. In traditional coagulation (TC) process, the aggregation of primary Ala-dissolved organic matter (DOM) complexes with in-situ-formed polynuclear species generated a large average floc size (226 µm), which was proved to be efficient for DOC removal (52.6%). The weak connections between dissolved Ala-DOM complexes and MPs led to the negligible changes of dissolved Al after seeding with MPs in AlCl3. A significant interaction between MPs and Al13 was observed, in which the MPs-Al13-DOM complexes were proposed to be responsible for the significant improvement of DOC removal (from 47% to 52%) and residual total Al reduction (from 1.05 to 0.27 mg Al L-1) with MPs addition. Al30 produced a lower floc fractal dimension (Df = 1.88) than AlCl3 (2.08) and Al13 (1.99) in the TC process, whereas its floc strength (70.9%) and floc recovery (38.5%) were higher than the others. Although more detached fragments were produced with MPs addition, the effective sedimentation of these fragments with the applied magnetic field led to the decrease of residual turbidity and colloidal Al in Al30. The dependence of coagulation behavior to MPs and different Al species can be applied to guide the application of an effective MSC process.


Assuntos
Purificação da Água , Alumínio , Cloreto de Alumínio , Floculação , Fenômenos Magnéticos , Polímeros
3.
Sci Total Environ ; : 143142, 2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33168253

RESUMO

Modifying the surface of an anode can improve electroactive bacteria (EAB) enrichment, thereby enhancing the performance of the associated microbial electrochemical systems (MESs). In this study, biosynthetic FeS nanoparticles were used to modify the anode in MESs. The experimental results demonstrated that the stable maximum voltage of the FeS composited biochar (FeS/BC)-modified anode reached 0.72 V, which is 20% higher than that of the control. The maximum power density with the FeS/BC anode was 793 mW/m2, which is 46.31% higher than that obtained with the control (542 mW/m2). According to cyclic voltammetry (CV) analysis, FeS/BC facilitates the direct electron transfer between bacteria and the electrode. The biomass protein concentration of the FeS/BC anode was 841.75 µg/cm2, which is almost 1.5 times higher than that of the carbon cloth anode (344.25 µg/cm2); hence, FeS/BC modification can promote biofilm formation. The composition of Geobacter species on the FeS/BC anode (75.16%) was much higher than that on the carbon cloth anode (4.81%). All the results demonstrated that the use of the biosynthetic FeS/BC anode is an environmentally friendly and efficient strategy for enhancing the electroactive biofilm formation and EAB enrichment in MESs.

4.
Sci Total Environ ; : 143717, 2020 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-33220995

RESUMO

Magnetic particles (MPs) assisted powdered activated carbon (PAC) is a promising composite material for adsorption removal of micropollutants. The fractional amount of Fe3O4 impacts the balance between adsorption capacity and magnetic property of magnetic activated carbons (MPACs), and therefore it affects the extent of sulfamethoxazole (SMX) removal. Here, five MPACs with different mass ratios of Fe3O4: PAC (1:1, 1:2, 1:4, 1:6, and 1:8) were prepared using a hydrothermal method and characterized by various spectroscopic methods. The spherical shaped MPs were monolayerly deposited on PAC with fewer pores blocked when the mass ratio of Fe3O4 was comparatively low (≤ 20%). MPAC6 (14.3 wt% of Fe3O4) had the best overall performance, with good Langmuir adsorption capacities for SMX (173.0 mg g-1) and excellent magnetic properties (9.0 emu g-1). Corresponding adsorption kinetics fitted well with the pseudo second-order kinetic model. The negative ΔG0 (-25.6 to -27.2 KJ mol-1) and ΔH0 (-9.14 KJ mol-1), and positive ΔS0 (0.55 KJ mol-1 K-1) properties indicated the spontaneous and exothermic nature of the adsorption process accompanied by an increase in entropy. The strong cation-assisted electron donor-acceptor and hydrophobic interactions were contributed to a high extent of SMX removal in the pH range of 2-4. Formation of negative charge-assisted H-bonds was responsible for the adsorption of hydrophilic SMX- on negatively charged MPAC6 in alkaline solution. Desorption and regeneration experiments showed SMX removal was still 92.3% in the 5th cycle. These findings give valuable insights into the interactions between SMX and MPACs and guide for choosing sustainable magnetic adsorbents for environmental applications.

5.
Plants (Basel) ; 9(10)2020 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-33066482

RESUMO

Abscisic acid (ABA) plays a crucial role in various aspects of plant growth and development, including fruit development and ripening, seed dormancy, and involvement in response to various environmental stresses. In almost all higher plants, ABA signal transduction requires three core components; namely, PYR/PYL/RCAR ABA receptors (PYLs), type 2C protein phosphatases (PP2Cs), and class III SNF-1-related protein kinase 2 (SnRK2s). The exploration of these three core components is not comprehensive in soybean. This study identified the GmPYL-PP2C-SnRK2s gene family members by using the JGI Phytozome and NCBI database. The gene family composition, conservation, gene structure, evolutionary relationship, cis-acting elements of promoter regions, and its coding protein domains were analyzed. In the entire genome of the soybean, there are 21 PYLs, 36 PP2Cs, and 21 SnRK2s genes; further, by phylogenetic and conservation analysis, 21 PYLs genes are classified into 3 groups, 36 PP2Cs genes are classified into seven groups, and 21 SnRK2s genes are classified into 3 groups. The conserved motifs and domain analysis showed that all the GmPYLs gene family members contain START-like domains, the GmPP2Cs gene family contains PP2Cc domains, and the GmSnRK2s gene family contains S_TK domains, respectively. Furthermore, based on the high-throughput transcriptome sequencing data, the results showed differences in the expression patterns of GmPYL-PP2C-SnRK2s gene families in different tissue parts of the same variety, and the same tissue part of different varieties. Our study provides a basis for further elucidation of the identification of GmPYL-PP2C-SnRK2s gene family members and analysis of their evolution and expression patterns, which helps to understand the molecular mechanism of soybean response to abiotic stress. In addition, this provides a conceptual basis for future studies of the soybean ABA core signal pathway.

6.
Bioresour Technol ; 315: 123764, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32682259

RESUMO

Different voltages were applied to anaerobic treatment to investigate the enhancement effects and the changes of microbial community structure. The results indicated that the best appropriate voltage was 0.10 V, COD removal increased by 16.72% at first 6 h and cumulative CH4 production increased by 23.39%. Average methane yield was 15.69% higher than that of control. The sludge measurements indicated that voltage addition could promote the interspecies electron transfer to produce more methane. The strengthening effect of voltage could be sustained for a short period of time when the voltage was removed. Microbial community analysis revealed that the changes of Methanothrix and Methanolinea resulted in higher biogas production. The increases of Smithella and Geobacter improved the possibility of "electronic syntrophism" between microorganisms and promoted the performance of DIET process. The results would provide the theoretical supports for enhancing the anaerobic treatment efficiency by voltages.


Assuntos
Esgotos , Águas Residuárias , Anaerobiose , Biocombustíveis , Reatores Biológicos , Metano
7.
Phys Rev Lett ; 124(16): 163201, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32383919

RESUMO

We demonstrate the possibility of realizing Young's double-slit interference in a hydrogen atom via ab initio simulations. By exposing the hydrogen atom to a high-frequency intensive laser pulse, the bound state distorts into a dichotomic Kramers-Henneberger state whose photoelectron momentum distribution imprints a double-slit interference structure. The dichotomic hydrogen atom presents molecular peculiarities, such as charge-resonance enhanced ionization, electron spin flipping due to the non-Abelian Berry phase. In return, the photoelectron momentum distribution carrying the double-slit interference structure provides unambiguous evidence on the existence of Kramers-Henneberger states, and thus the adiabatic stabilization.

8.
Environ Sci Pollut Res Int ; 26(32): 33341-33350, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31520391

RESUMO

The aim of this study was to compare environmental pollution and ecological states of two different areas of the Songhua River areas: near Harbin City and Tongjiang City, located at a distance of about 500 km downstream. The anthropogenic pollution concentrations of heavy metals (HM) were determined. The results showed that concentrations of eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the water were in the range of 0.001-0.588 mg/L for Tongjiang and 0.001-0.508 mg/L for Harbin, while that in sediments were in the range of 0.67-1575.37 mg/kg for Tongjiang and 0.07-5617.13 mg/kg for Harbin, respectively. Bivalves from tested sites exposed to environmental pollution exhibited significantly different physiological states. The latter was assessed using the method of physiological loading, based on measuring the recovery time (Trec) of heart rate (HR) after removal of the load. Trec in mussels from Harbin was recorded in the range of 151 to 234 min, while that from Tongjiang was only 115 min. Cd, Cu, Pb, and Zn in mollusk soft tissues were also determined for Harbin and Tongjiang, respectively. The metal pollution index (MPI) and bioconcentration factor (BCF) in the mollusks were calculated for each metal. BCF in the mussels from the Tongjiang area was lower than that from the Harbin area. Physiological testing, as well as the concentration of HM in water, and sediment, and also the bioaccumulation of HM in tissue showed that the ecological state of the Tongjiang area was better than that of Harbin. Apparently, after more extensive studies, a methodological approach of assessing the ecological state of water areas, based on physiological state testing of aboriginal mollusks, could be used in the monitoring of pollution effects in water bodies and streams.


Assuntos
Biomarcadores Ambientais , Monitoramento Ambiental , Poluentes Químicos da Água/análise , Animais , Bivalves , China , Cromatografia Gasosa , Ecologia , Sedimentos Geológicos/análise , Metais Pesados/análise , Medição de Risco , Rios/química
9.
Ecotoxicol Environ Saf ; 164: 409-415, 2018 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-30142607

RESUMO

To investigate the potential cancer risk resulting from exposure to air pollutants, polycyclic aromatic hydrocarbons (PAHs) bound to airborne particles (PM2.5) were assessed in one outdoor environment and four indoor environments before and during the Spring Festival of 2015. The average total PAH concentration was site-dependent, and the concentration decreased before and during the Spring Festival. Fluoranthene (Flt) was the most commonly occurring among the 16 priority PAHs, and benzo(a)pyrene (BaP) accounted for the largest portion of the total carcinogenic potency of PAHs in PM2.5. The average BaP levels, in both indoor and outdoor environments, considerably exceeded the maximum permissible risk level of 1 ng/m3. Hazard quotients were found to be much less than 1, indicating little risk in terms of non-carcinogenic effects. Carcinogenic health risks resulting from possible carcinogens were determined to be much less than 1.00E-06. According to the California and WHO reference protocol, using empty room data to estimate the carcinogenic health risk produced values that were 10% lower than those calculated using outdoor environmental data.


Assuntos
Poluição do Ar em Ambientes Fechados/efeitos adversos , Exposição Ambiental/efeitos adversos , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Benzo(a)pireno/análise , Carcinógenos , Fluorenos/análise , Humanos , Modelos Teóricos , Medição de Risco , Fatores de Risco , Estações do Ano
10.
Environ Pollut ; 242(Pt B): 1669-1677, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30077404

RESUMO

We describe a batch-extraction with simulated digestive fluid (salivary fluid, gastric fluid and intestinal fluid) to estimate the bioaccessibility of inhaled trace metals (TMs) in particulate matter less than 10 and 2.5 µm in aerodynamic diameter (PM10 and PM2.5). Concentrations of the assayed TMs (As, Cd, Cr, Ni, Mn, Cu, Zn, Sb, Hg and Pb) were determined in PM10 and PM2.5 samples by inductively coupled plasma-mass spectrometry. The TMs with the largest soluble fractions for airborne PM collected from winter and summer in saliva were Mn and Sb, respectively; in seasons this became Co in gastric fluid and Cu in intestinal fluid. Clearly, bioaccessibility is strongly dependent on particle size, the component of simulated digestive fluids (e.g., pH, digestive enzymes pepsin and trypsin), and the chemical properties of metal ions. The particle size and seasonal variation affected the inhaled bioaccessible fraction of PM-bound TMs during mucociliary clearance, which transported PM from the tracheal and the bronchial region to the digestive system. This study provides direct evidence for TMs in airborne PM being bioaccessible TMs are likely to possess an enhanced digestive toxic potential due to airborne PM pollution.


Assuntos
Poluentes Atmosféricos/análise , Arsênico/análise , Metais Pesados/análise , Material Particulado/análise , Poluentes Atmosféricos/química , Arsênico/química , Disponibilidade Biológica , China , Cidades , Monitoramento Ambiental , Suco Gástrico/química , Humanos , Exposição por Inalação , Secreções Intestinais/química , Metais Pesados/química , Tamanho da Partícula , Material Particulado/química , Saliva/química , Estações do Ano
11.
Appl Microbiol Biotechnol ; 102(16): 7147-7158, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29869072

RESUMO

The quest to understand and subsequently improve the role played by bacteria and archaea in the degradation of organic matter both in natural and engineered anaerobic ecosystems has intensified the utilization of nanoparticles. Microbial communities are known to syntrophically cooperate during the anaerobic conversion of substrates into methane gas via the direct exchange of electrons. In this study, the role of hematite (Fe2O3-750 mg/L) and multi-walled carbon nanotubes (MWCNTs-1500 mg/L) during the degradation of beet sugar industrial wastewater (BSIW) in a batch experiment was investigated. Hematite and MWCNTs enhanced methane gas generation by 35 and 20%, respectively. Furthermore, microbial syntrophic communities might have exchanged metabolic electrons more directly, with hematite and MWCNTs serving as electron conduits between the homoacetogens and methanogens, thereby establishing a direct interspecies electron transfer (DIET) pathway. Additionally, hematite and MWCNTs enriched the bacteria Firmicutes while Chloroflexi reduced in abundance. Scanning electron microscopy and confocal laser scanning microscopy demonstrated that extracellular polymeric substances had noticeable interactions with both hematite and MWCNTs. Our findings provide vital information for more understanding of the response of microbes to hematite and MWCNTs in a complex natural environment.


Assuntos
Compostos Férricos/química , Compostos Férricos/farmacologia , Microbiologia Industrial/métodos , Microbiota/efeitos dos fármacos , Nanotubos de Carbono/química , Águas Residuárias , Beta vulgaris/química , Metano/biossíntese , Açúcares/metabolismo
12.
Chemosphere ; 207: 534-542, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29843030

RESUMO

Boron nitride Nanosheets (BNNSs) was fabricated with a method of heating the mixture of boric acid and urea in N2 atmosphere and used to remove estrone (E1) from water. The obtained BNNSs exhibited a higher surface area of 896 m2/g, a large pore volume of 0.76 cm3/g, and only few layers (0.398 nm) with the boric acid and urea ratio of 1:80. The layer number of BNNSs decreased from 15 to 4 with the mole ratio of boric acid and urea decreasing from 1:20 to 1:80, which was identified by SEM, TEM, AFM and BET measurements. More importantly, BNNSs presented an outstanding adsorption performance for estrone with the adsorption capacity of 249.15 mg E1/g BNNSs. The adsorption process could be best fitted by pseudo second-order kinetic model and the equilibrium data at different temperatures were well fitted by Langmuir isotherm model. The thermodynamics analysis revealed that E1 adsorption on BNNSs was spontaneous (ΔG = -29.33 kJ mol-1), enthalpy-retarded (ΔH = 29.75 kJ mol-1), entropy-driven (ΔS = 198.26 J mol-1 K-1), and mostly chemical adsorption. The adsorption rates of E1 in water were sharply enhanced with thinner BNNSs as absorbents and removal efficiency by BN-60 regenerated after 6 times was above 95%, it was shown that the surface areas, mesopores and remarkable structure played important roles in the adsorption process. The firmness of E1 onto BNNSs and the stability of adsorption efficiency made BNNSs as a potential absorbent for efficient removal of E1 from wastewater.


Assuntos
Compostos de Boro/química , Estrona/isolamento & purificação , Nanopartículas/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cinética , Termodinâmica
13.
Environ Pollut ; 238: 554-561, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29605615

RESUMO

Females can be exposed to toxic elements in lip cosmetics following ingestion. The bioaccessibility of Cr, Mn, Co, Ni, Cu, Cd, Sb and Pb in lip cosmetics (n = 32) were assessed via the dilute HCl extraction method, In Vitro Gastrointestinal protocol (IVG) and the United States Pharmacopeia Methodology (USPM), and then health risks were characterized. The total concentrations of trace metals (TMs) in lip cosmetics were in the range of 15.55-111.97 mg/kg (Mean: 60.99 mg/kg). Cu, Pb and Cr were the three major TMs and accounting for >75% of the total concentrations. Except Sb and Pb in 4/32 and 4/32 samples were higher than the US FDA (Food and Drug Administration of the United States) limits, the other TMs were lower than that limits. Only bioaccessible Pb in all samples significantly exceeded the FDA limit 0.1 mg/kg in candy. Using IVG or USPM might be preferable for evaluating the TMs exposure over HCl since they better represent gastrointestinal physiology. The estimated average daily intake (ADI) of bioaccessible ∑TMs through lip cosmetics ingestion of career women and female college students were under safety level. The long-term exposure of bioaccessible TMs by lip cosmetics using would inevitably cause non-carcinogenic health risk. This is the first report on the in vitro tests used for evaluating bioaccessible TMs in lip cosmetics.


Assuntos
Cosméticos/análise , Exposição Ambiental/estatística & dados numéricos , Metais/análise , Comportamento do Consumidor , Ingestão de Alimentos , Feminino , Humanos , Lábio , Metais Pesados , Medição de Risco , Estudantes , Oligoelementos
14.
Water Res ; 136: 54-63, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29494896

RESUMO

Packing nano mediators into anaerobic system is an attractive technology to strengthen refractory pollutant removal and methane production from wastewater, but is limited by the drawbacks such as easy loss and poor mass transfer. In this study, GAC/NZVI mediator was added into EGSB reactor to investigate the enhancement effects and mechanism for anaerobic digestion of tetracycline wastewater and its impacts on microbial community structure. The results indicated that GAC/NZVI could enhance COD and TOC removal by 12.1% and 10.3%, while have no evident influence on tetracycline removal and sulfide production. The biogas production and methane content were increased by 21.2% and 26.9%, respectively. GAC/NZVI addition resulted in formation of densely packed aggregates, and evidently increased the electrical conductivity and EPS content in sludge. Fe content in sludge was 20.43% with the loss of only 5.4% during 34 d operation. Microbial community analysis revealed that GAC/NZVI addition could both increase the Chao 1 richness index and Shannon diversity index of bacteria and archaea. It was notable that total methanogens contents increased from 74.7% to 81.74% at genera level, resulting in higher methane production, while Treponema increase might promote the degradation of tetracycline and its metabolite, leading to higher COD removal.


Assuntos
Archaea/metabolismo , Bactérias/metabolismo , Reatores Biológicos/microbiologia , Metano/metabolismo , Tetraciclina/metabolismo , Poluentes Químicos da Água/metabolismo , Anaerobiose , Biodegradação Ambiental , Biocombustíveis/análise , Esgotos/química , Esgotos/microbiologia , Tetraciclina/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise
15.
Water Res ; 117: 87-94, 2017 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-28390238

RESUMO

The accelerated use of iron oxide nanoparticles (IONPs) and multi-wall carbon nanotubes (MWCNTs) in the consumer and industrial sectors has triggered the need to understand their potential environmental impact. The response of anaerobic granular sludge (AGS) to IONPs and MWCNTs during the anaerobic digestion of beet sugar industrial wastewater (BSIW) was investigated in this study. The IONPs increased the biogas and subsequent CH4 production rates in comparison with MWCNTs and the control samples. This might be due to the utilization of IONPs and MWCNTs as conduits for electron transfer toward methanogens. The MWCNTs majorly enriched the bacterial growth, while IONP enrichment mostly benefitted the archaea population. Furthermore, scanning electron microscopy and confocal laser scanning microscopy revealed that AGS produced extracellular polymeric substances, which interacted with the IONPs and MWCNTs. This provided cell protection and prevented the nanoparticles from piercing through the membranes and thus cytotoxicity. The results provide useful information and insights on the adjustment of anaerobic microorganisms to the natural complex environment based on nanoparticles infiltration.


Assuntos
Esgotos/microbiologia , Águas Residuárias/microbiologia , Beta vulgaris , Reatores Biológicos/microbiologia , Nanopartículas , Nanotubos de Carbono/toxicidade
16.
Environ Sci Pollut Res Int ; 24(16): 14387-14395, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28432623

RESUMO

Performance and microbial community composition were evaluated in a two-phase anaerobic and aerobic system treating sulfate-rich cellulosic ethanol wastewater (CEW). The system was operated at five different chemical oxygen demand (COD)/SO42- ratios (63.8, 26.3, 17.8, 13.7, and 10.7). Stable performance was obtained for total COD removal efficiency (94.5%), sulfate removal (89.3%), and methane production rate (11.5 L/day) at an organic loading rate of 32.4 kg COD/(m3·day). The acidogenic reactor made a positive contribution to net VFAs production (2318.1 mg/L) and sulfate removal (60.9%). Acidogenic bacteria (Megasphaera, Parabacteroides, unclassified Ruminococcaceae spp., and Prevotella) and sulfate-reducing bacteria (Butyrivibrio, Megasphaera) were rich in the acidogenic reactor. In the methanogenic reactor, high diversity of microorganisms corresponded with a COD removal contribution of 83.2%. Moreover, methanogens (Methanosaeta) were predominant, suggesting that these organisms played an important role in the acetotrophic methanogenesis pathway. The dominant aerobic bacteria (Truepera) appeared to have been responsible for the COD removal of the SBR. These results indicate that dividing the sulfate reduction process could effectively minimize sulfide toxicity, which is important for the successful operation of system treating sulfate-rich CEW.


Assuntos
Reatores Biológicos , Etanol/metabolismo , Eliminação de Resíduos Líquidos , Bactérias , Análise da Demanda Biológica de Oxigênio , Sulfatos , Águas Residuárias
17.
Sci Total Environ ; 576: 628-636, 2017 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-27810750

RESUMO

In order to better understand the risk to students' health caused by pollution derived from fine particulate matter with an aerodynamic diameter <2.5mm (PM2.5), this study collected 189 samples in one outdoor and four different functional indoor environments of a research center in a university campus. Trace metals (TMs) bound to PM2.5 in outdoor and indoor environments were measured using X-ray fluorescence spectrometry. The TMs measured were: As, Co, Cd, Cr, Ni, Cu, Zn, Mn, Hg, and Pb. The measurements of PM2.5-bound TMs before and during the 2015 Spring Festival held in Northeast China were compared. Results showed that pollution due to PM2.5-bound TMs in outdoor and indoor environments was higher before than during the Spring Festival. Cu (in three indoor environments) and Zn (in an outdoor environment) showed the highest concentrations among the ten TMs that were measured. Hg showed the lowest concentrations in all the environments analyzed. The concentrations of PM2.5-bound TMs declined among four indoor environments in the following order: the atrium, the students' office (sampled just nine days before the Spring Festival), the laboratory, and an empty room. The potential carcinogenic and non-carcinogenic health risks derived from PM2.5-bound TMs were within safe limits for graduate and undergraduate students, according to the standards established by the United States Environmental Protection Agency (USEPA).


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental , Material Particulado/análise , Medição de Risco , Estações do Ano , China , Humanos , Tamanho da Partícula , Universidades
18.
Sci Rep ; 6: 34135, 2016 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-27694968

RESUMO

This paper aimed to investigate the influences of operational parameters and aqueous chemical conditions on transport behaviors of cerium oxides nanoparticles (CeO2-NPs) in saturated silica media. Results indicated that increasing rates of attachment efficiency (α) were related with cationic types, and critical deposition concentration (CDC) for divalent cation (Ca2+ and Mg2+) were more than 31-fold of that for monovalent cation (Na+ and K+). Increase or reduction of electrolyte pH could both promote the mobility of CeO2-NPs in glass beads, while influence was more evident at alkaline conditions. α increased linearly with NPs concentrations, while decreased linearly with flow velocity in the column, and effects were related with electrolyte contents. Presence of surfactants could sharply decreased α, and SDS was more effective to facilitate CeO2-NPs transport than Triton X-100. With DOMs concentrations increasing, α firstly kept constant, then sharply declined, and finally reduced very slowly. The influence of DOMs on NPs deposition was in order of SA > HA > TA > BSA. Overall, this study revealed that aqueous chemical conditions was crucial to NPs transport in porous media, and would provide significant information for our understanding on the fate and transport of nanoparticles in natural environment.

20.
Sci Total Environ ; 569-570: 234-243, 2016 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-27343942

RESUMO

The widespread utilization of silver nanoparticles (AgNPs) in industrial and commercial products inevitably raises the release into wastewater that might cause potential negative impacts on sewage treatment system. In this paper, long-term exposure experiments at four levels were conducted to determine whether AgNPs caused adverse impacts on nutrient removals in sequencing batch reactors (SBRs) and changes of microbial community structure. Compared with the control reactor (without AgNPs), carbon, nitrogen and phosphorus removal in presence of 0.1mg/L AgNPs was no difference. However, presence of 1.0 and 10mg/L AgNPs decreased the average removal efficiencies of COD from 95.4% to 85.2% and 68.3%, ammonia nitrogen from 98.8% to 71.2% and 49%, SOP from 97.6% to 75.5% and 54.1%, respectively. It was found that AgNPs could accumulate in sludge with the distribution coefficients of 39.2-114L/g, inhibit the protein and polysaccharide production in EPS, reduce the SOUR of sludge, and greatly increase LDH release from microbial cells. The illumina high-throughput sequencing results indicated that AgNPs concentration changed the structures of bacterial communities, associating with the effects of AgNPs on reactor performance. Sequence analyses showed that Proteobacteria, Bacteroidetes and Acidobacteria were the dominant phyla. It was notable that AgNPs addition reduced the contents of several nitrifying bacteria at genera level in sludge, leading to the lower removal of nitrogen.


Assuntos
Nanopartículas Metálicas , Microbiota , Prata/metabolismo , Eliminação de Resíduos Líquidos , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos/microbiologia , Nitrogênio/metabolismo , Fósforo/metabolismo , Esgotos/análise , Prata/farmacologia , Fatores de Tempo
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