Microbial structure and activity of UASB granules treating different wastewaters

1994 ◽  
Vol 30 (12) ◽  
pp. 87-96 ◽  
Author(s):  
H. H. P. Fang ◽  
H. K. Chui ◽  
Y. Y. Li
Keyword(s):  
Layered Structure ◽  
Soluble Carbohydrates ◽  
Uniform Structure ◽  
Supporting Evidence ◽  
Structural Element ◽  
Methanogenic Activity ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Uasb Granules ◽  
And Diffusion

The microstructure of three types of UASB granules respectively treating sucrose, glutamate and brewery wastewaters in mesophilic conditions were analyzed by light, scanning electron and transmission electron microscopies, along with the specific methanogenic activity (SMA) of the granules. Results showed that the granule's microstructure was dependent on the nature of the substrate. Those degrading soluble carbohydrates exhibited a layered structure, while those degrading glutamate exhibited a rather uniform structure. Such a difference was explained based on the substrate's rates of acidogenesis and diffusion. A model of the typical layered structure was proposed. In addition, the acetoclastic Methanothrix was found as the key structural element in all the granules, suggesting that it plays an important role in granulation. Three types of syntrophic microcolonies were found to be abundant in granules degrading soluble carbohydrates: two were juxtapositioned syntrophic microcolonies, each was composed of hydrogen-producing acetogens and hydrogen-consuming methanogens, while the third was a cluster-type of syntrophic association between two microcolonies. The SMA data using individual VFA as substrate provided supporting evidence to the observations of the bacterial compositions in the granules.

Microstructural analysis of UASB granules treating brewery wastewater

1995 ◽  
Vol 31 (9) ◽  
pp. 129-135 ◽  
Author(s):  
H. H. P. Fang ◽  
H. K. Chui ◽  
Y. Y. Li
Keyword(s):  
Light Microscopy ◽  
Outer Layer ◽  
Microstructural Analysis ◽  
The Other ◽  
Uasb Reactor ◽  
Brewery Wastewater ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Uasb Granules ◽  
Syntrophic Associations

The microstructure of granules from a full-scale UASB reactor treating brewery wastewater was examined using light microscopy as well as the scanning and transmission electron microscopies. The granules typically have a complex, layered structure. The outer layer of the granule was densely packed with various types of bacteria, including cocci, bacilli, Methanosarcina, and Methanothrix. The second layer was composed of a matrix of Methanothrix with two types of microcolony showing evidence of syntrophic associations between hydrogen-producing acetogens and hydrogen-consuming methanogens. The interior of the granule, on the other hand, was predominantly Methanothrix with scattered microcolonies of syntrophic associations, which became sparse and disappeared toward the centre core of the granule.

Structure and methanogenic activity of granules from an ASBR treating dilute wastewater at low temperatures

1997 ◽  
Vol 36 (6-7) ◽  
pp. 149-156 ◽  
Author(s):  
Gouranga C. Banik ◽  
Timothy G. Ellis ◽  
Richard R. Dague
Keyword(s):  
Electron Microscopy ◽  
Low Temperatures ◽  
Significant Variation ◽  
Uniform Structure ◽  
Microbial Structure ◽  
Methanogenic Activity ◽  
Transmission Electron ◽  
Dry Milk ◽  
Specific Methanogenic Activity ◽  
Role Activity

The microstructure of ASBR granules treating synthetic substrate consisting of non-fat-dry-milk at temperatures of 5, 15 and 25°C was analyzed by scanning and transmission electron microscopy. The specific methanogenic activity of the granules was tested at 35°C using acetate and mixtures of acetate and propionate as substrates. Results revealed no significant variation in microbial structure for the different temperature conditions. Granules at 15 and 25°C exhibited uniform structure, predominantly Methanothrix-like microorganisms, while granules at 5°C indicated the existence of a layered structure. This reinforces the hypothesis that layering is largely substrate specific, but also suggests that temperature may have a role. Activity tests revealed that even after long periods of operation at psychrophilic temperatures, mesophilic bacteria are active and have the ability to rapidly degrade acetate and mixtures of acetate and propionate.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

scholarly journals V2O3/C composite fabricated by carboxylic acid-assisted sol–gel synthesis as anode material for lithium-ion batteries

2021 ◽  
Author(s):  
G. S. Zakharova ◽  
E. Thauer ◽  
A. N. Enyashin ◽  
L. F. Deeg ◽  
Q. Zhu ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Lithium Ion Batteries ◽  
Sol Gel ◽  
Carbon Sources ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Battery Electrode ◽  
Sol Gel Synthesis

AbstractThe potential battery electrode material V2O3/C has been prepared using a sol–gel thermolysis technique, employing vanadyl hydroxide as precursor and different organic acids as both chelating agents and carbon sources. Composition and morphology of resultant materials were characterized by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies, physical sorption, and elemental analysis. Stability and electronic properties of model composites with chemically and physically integrated carbon were studied by means of quantum-chemical calculations. All fabricated composites are hierarchically structured and consist of carbon-covered microparticles assembled of polyhedral V2O3 nanograins with intrusions of amorphous carbon at the grain boundaries. Such V2O3/C phase separation is thermodynamically favored while formation of vanadium (oxy)carbides or heavily doped V2O3 is highly unlikely. When used as anode for lithium-ion batteries, the nanocomposite V2O3/C fabricated with citric acid exhibits superior electrochemical performance with an excellent cycle stability and a specific charge capacity of 335 mAh g−1 in cycle 95 at 100 mA g−1. We also find that the used carbon source has only minor effects on the materials’ electrochemical performance.

Physical Simulation of Weldability of Weldox 1300 Steel

2013 ◽  
Vol 762 ◽  
pp. 551-555 ◽  
Author(s):  
Marek Stanislaw Węglowski ◽  
Marian Zeman ◽  
Miroslaw Lomozik
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Physical Simulation ◽  
High Strength ◽  
Parent Material ◽  
Cooling Time ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Transformation Diagrams ◽  
The Impact

In the present study, the investigation of weldability of new ultra-high strength - Weldox 1300 steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on the microstructure and mechanical properties of the heat affected zone (HAZ). In the frame of these investigation the microstructure was studied by the light (LM) and transmission electron microscopies (TEM). It has been shown that the microstructure of the Weldox 1300 steel is composed of tempered martensite, and inside the laths the minor precipitations mainly V(CN) and molybdenum carbide Mo2C were observed. Mechanical properties of parent material were analysed by the tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 - 300 s. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The results show that the impact toughness and hardness decrease with the increase of t8/5 under the condition of a single thermal cycle in simulated HAZ. The continuous cooling transformation diagrams (CCT-W for welding conditions) of Weldox 1300 steel for welding purposes was also elaborated. The steel Weldox 1300 for cooling time in the range of 2,5 - 4 s showed martensite microstructure, for time from 4 s to 60 s mixture of martensite and bainite, and for longer cooling time mixture of ferrite, bainite and martensite. The results indicated that the weldability of Weldox 1300 steel is limited and to avoid the cold cracking the preheating procedure or medium net linear heat input should be used.

scholarly journals Multi-Scale Investigation of Body-Glaze Interface in Ancient Ceramics

Heritage ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 2480-2494 ◽  
Author(s):  
Marie Godet ◽  
Gauthier Roisine ◽  
Emmie Beauvoit ◽  
Daniel Caurant ◽  
Odile Majérus ◽  
...  
Keyword(s):  
Single Crystals ◽  
The Body ◽  
Firing Time ◽  
Body System ◽  
Slow Cooling ◽  
French Renaissance ◽  
Electron Microscopies ◽  
Multi Scale ◽  
Continuous Layer ◽  
Transmission Electron

Bernard Palissy is a French Renaissance ceramist renowned for his masterpieces called Rustiques Figulines on which dozens of glazes of different chemistries (and thus firing behaviors) coexist harmoniously. This study aims at gathering information on the master procedure -never revealed- by investigating the body-glaze interface region (focusing on iron-colored honey transparent glaze-white body system). Optical and electron microscopies including transmission electron microscopy (TEM) are used to characterize the micro and nanostructure of both archaeological and replicas interfaces elaborated in controlled conditions (firing time, cooling rate, addition of Al in the glazing mixture). Both types of interfaces are comparable: a modified paste area from which are growing a relatively continuous layer of interfacial crystals identified as lead feldspars (K,Ca)PbAl2Si2O8 micro-sized single-crystals incorporating mullite 3Al2O3.2SiO2 nano-sized single-crystals. Modification of the firing parameters and removal of Al from the glazing mixture change essentially the interface extension and the micro-crystals morphology. By comparing archaeological and replica interfaces and considering previous studies, we can now state that Palissy was very likely adding clay (Al) in his frit. Moreover, he was probably working with a firing time of more than 1 h followed by slow cooling in the oven.

Dual Beam Focused Ion Beam and Transmission Electron Microscopies of Nanoscale Sectioned Diatom Frustules

2007 ◽  
Vol 13 (S02) ◽  
Author(s):  
T Gutu ◽  
J Wu ◽  
C Jeffreys ◽  
C-H Chang ◽  
G Rorrer ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Electron Microscopies ◽  
Dual Beam ◽  
Transmission Electron

Influence of ethanol on the chain-ordering of carbonised polyaniline

2013 ◽  
Vol 67 (8) ◽  
Author(s):  
Zuzana Morávková ◽  
Miroslava Trchová ◽  
Elena Tomšík ◽  
Jaroslav Stejskal
Keyword(s):  
Molecular Structure ◽  
Pure Water ◽  
Nitrogen Atmosphere ◽  
Ethanol Mixture ◽  
Electron Microscopies ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Pani Salt ◽  
Chain Ordering ◽  
Pani Base

AbstractPolyaniline (PANI) was prepared by the oxidation of aniline hydrochloride with ammonium peroxydisulphate in water or in a water-ethanol mixture. In the presence of ethanol, PANI nanotubes and nanorods were observed. Both products were carbonised in a nitrogen atmosphere at 650°C. Initial and carbonised products were characterised by scanning and transmission electron microscopies, thermogravimetric analysis and wide-angle X-ray scattering. Their molecular structure was studied by UV-VIS, infrared, and Raman spectroscopies. Carbonised sample obtained from the PANI salt prepared in the presence of ethanol exhibits Raman spectrum which corresponds to a more ordered carbon-like material than carbonised samples obtained from the PANI base and the PANI salt prepared in pure water. The influence of ethanol present in the reaction mixture on the molecular and supra-molecular structure of PANI and, consequently, on the enhancement of chainordering of carbonised PANI is discussed.

scholarly journals New Electrospun ZnO:MoO3 Nanostructures: Preparation, Characterization and Photocatalytic Performance

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1476 ◽  
Author(s):  
Petronela Pascariu ◽  
Mihaela Homocianu ◽  
Niculae Olaru ◽  
Anton Airinei ◽  
Octavian Ionescu
Keyword(s):  
Photocatalytic Performance ◽  
Molybdenum Trioxide ◽  
Blue Shift ◽  
Band Gap Energy ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Electron Microscopies ◽  
Reaction Rate Constants ◽  
Transmission Electron ◽  
Electrospinning Method

New molybdenum trioxide-incorporated ZnO materials were prepared through the electrospinning method and then calcination at 500 °C, for 2 h. The obtained electrospun ZnO:MoO3 hybrid materials were characterized by X-ray diffraction, scanning and transmission electron microscopies, ultraviolet (UV)-diffuse reflectance, UV–visible (UV–vis) absorption, and photoluminescence techniques. It was observed that the presence of MoO3 as loading material in pure ZnO matrix induces a small blue shift in the absorption band maxima (from 382 to 371 nm) and the emission peaks are shifted to shorter wavelengths, as compared to pure ZnO. Also, a slight decrease in the optical band gap energy of ZnO:MoO3 was registered after MoO3 incorporation. The photocatalytic performance of pure ZnO and ZnO:MoO3 was assessed in the degradation of rhodamine B (RhB) dye with an initial concentration of 5 mg/L, under visible light irradiation. A doubling of the degradation efficiency of the ZnO:MoO3 sample (3.26% of the atomic molar ratio of Mo/Zn) as compared to pure ZnO was obtained. The values of the reaction rate constants were found to be 0.0480 h−1 for ZnO, and 0.1072 h−1 for ZnO:MoO3, respectively.

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