Biological sulfide removal under alkaline and aerobic conditions in a packed recycling reactor

2009 ◽  
Vol 59 (7) ◽  
pp. 1415-1421 ◽  
Author(s):  
A. González-Sánchez ◽  
S. Revah
Keyword(s):  
Oxidation Rate ◽  
Sulfide Oxidation ◽  
Specific Area ◽  
Alkaline Condition ◽  
Lower Growth ◽  
Oxidation Rates ◽  
Sulfide Removal ◽  
Nylon Fiber ◽  
Biofilm Development ◽  
Recycling Reactor

The biological sulfide removal from wastewater caustic streams can be achieved without significant dilution by alkaliphilic microorganisms which usually show lower growth and oxidation rates as compared with acidic and neutral bacteria. To improve volumetric removal rates under alkaline condition (pH 10), an Alkaliphilic Sulfide-oxidizing Bacteria Consortium (ASBC) was studied in a Packed Recycling Reactor (PRR). A commercial Nylon fiber resulted to be a convenient packing support for biofilm development as it has high specific area and similar hydrophobic propertie. The PRR reached a maximum sulfide oxidation rate of 100 mmol L−1 d−1 with efficiency close to 100%, representing an enhancement of 56% from the maximum sulfide oxidation rate reached for a free cell continuous culture. Higher sulfide loading rates induced oxygen limiting conditions reducing the biological activity despite the considerable biofilm attached on the nylon fiber.

Substrate oxidation during exercise in taekwondo athletes: impact of aerobic fitness status

2020 ◽  
Vol 16 (5) ◽  
pp. 371-376
Author(s):  
B. Taati ◽  
H. Rohani
Keyword(s):  
Aerobic Fitness ◽  
Oxidation Rate ◽  
Fat Oxidation ◽  
Potential Effect ◽  
Substrate Oxidation ◽  
Training Experience ◽  
Male Athletes ◽  
Fitness Level ◽  
Oxidation Rates ◽  
Maximal Fat Oxidation

The present study aimed to investigate the potential effect of different aerobic fitness levels on substrate oxidation in trained taekwondo athletes. 57 male athletes (age 21.10±7.79 years; VO2max 50.67±6.67 ml/kg/min) with regular weekly taekwondo training and training experience of at least three years completed a graded exercise test to exhaustion on a treadmill. Maximal fat oxidation (MFO), the exercise intensity related to MFO (Fatmax), and carbohydrate (CHO) oxidation rate were measured using indirect calorimetry methods. The athletes then were divided into a low (<50 ml/kg/min, n=18) and high (>50 ml/kg/min, n=39) VO2max group. The average MFO was higher in the high VO2max group than in the low VO2max group (0.46±0.19 vs 0.28±0.11 g/min; P<0.001). Although Fatmax tended toward higher values in the high VO2max group, no difference was observed between the groups (49.15±15.22 vs 42.42±12.37% of VO2max; P=0.18). It was also shown that the high VO2max group had a lower CHO oxidation rate and a higher fat oxidation rate at given exercise intensities. In conclusion, it seems that MFO and substrate oxidation rates in taekwondo athletes can be influenced by aerobic fitness level such that the athletes with higher VO2max appeared to use more fat as a fuel source for energy supply during a given exercise.

Final products and kinetics of biochemical and chemical sulfide oxidation under microaerobic conditions

2018 ◽  
Vol 78 (9) ◽  
pp. 1916-1924 ◽  
Author(s):  
Lucie Pokorna-Krayzelova ◽  
Dana Vejmelková ◽  
Lara Selan ◽  
Pavel Jenicek ◽  
Eveline I. P. Volcke ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Oxidation Rate ◽  
Elemental Sulfur ◽  
Sulfide Oxidation ◽  
Cost Effective ◽  
Anaerobic Treatment ◽  
Batch Experiments ◽  
Cost Effective Method ◽  
Microaerobic Conditions ◽  
Kinetics Of

Abstract Hydrogen sulfide is a toxic and usually undesirable by-product of the anaerobic treatment of sulfate-containing wastewater. It can be removed through microaeration, a simple and cost-effective method involving the application of oxygen-limiting conditions (i.e., dissolved oxygen below 0.1 mg L−1). However, the exact transformation pathways of sulfide under microaerobic conditions are still unclear. In this paper, batch experiments were performed to study biochemical and chemical sulfide oxidation under microaerobic conditions. The biochemical experiments were conducted using a strain of Sulfuricurvum kujiense. Under microaerobic conditions, the biochemical sulfide oxidation rate (in mg S L−1 d−1) was approximately 2.5 times faster than the chemical sulfide oxidation rate. Elemental sulfur was the major end-product of both biochemical and chemical sulfide oxidation. During biochemical sulfide oxidation elemental sulfur was in the form of white flakes, while during chemical sulfide oxidation elemental sulfur created a white suspension. Moreover, a mathematical model describing biochemical and chemical sulfide oxidation was developed and calibrated by the experimental results.

UK landfill methane emissions: Use of mobile plume measurements and carbon isotopic characterisation to reassess oxidation rates for open and closed sites 

2021 ◽  
Author(s):  
Semra Bakkaloglu ◽  
Dave Lowry ◽  
Rebecca Fisher ◽  
James France ◽  
Euan Nisbet
Keyword(s):  
Methane Oxidation ◽  
Mole Fraction ◽  
Oxidation Rate ◽  
Methane Emissions ◽  
Isotopic Signature ◽  
Oxidation Rates ◽  
Landfill Cover ◽  
Carbon Isotopic ◽  
Landfill Sites ◽  
The Impact

&lt;p&gt;Biological methane oxidation in landfill cover material can be characterised using stable isotopes. Methane oxidation fraction is calculated from the carbon isotopic signature of emitted CH&lt;sub&gt;4&lt;/sub&gt;, with enhanced microbial consumption of methane in the aerobic portion of the landfill cover indicated by a shift to less depleted isotopic values in the residual methane emitted to air. This study was performed at four southwest England landfill sites. Mobile mole fraction measurement at the four sites was coupled with Flexfoil bag sampling of air for high-precision isotope analysis. Gas well samples collected from the pipeline systems and downwind plume air samples were utilized to estimate methane oxidation rate for whole sites. This work was designed to assess the impact on carbon isotopic signature and oxidation rate as UK landfill practice and waste streams have changed in recent years.&lt;/p&gt;&lt;p&gt;The landfill status such as closed and active, seasonal variation, cap stripping and site closure impact on landfill isotopic signature and oxidation rate were evaluated. The isotopic signature of &lt;sup&gt;13&lt;/sup&gt;C-CH&lt;sub&gt;4&lt;/sub&gt; values of emissions varied between -60 and -54&amp;#8240;, with an averaged value of -57 +- 2&amp;#8240; for methane from closed and active landfill sites. Methane emissions from older, closed landfill sites were typically more enriched in &lt;sup&gt;13&lt;/sup&gt;C than emissions from active sites. This study found that the isotopic signature of &lt;sup&gt;13&lt;/sup&gt;C-CH&lt;sub&gt;4&lt;/sub&gt; of fugitive methane did not show a seasonal trend, and there was no plume observed from a partial cap stripping process to assess changes in &lt;sup&gt;13&lt;/sup&gt;C-CH&lt;sub&gt;4&lt;/sub&gt;&amp;#160;&amp;#160;isotopic signatures of emitted methane. Also, the closure of an active landfill cell caused a significant decrease in mole fraction of measured CH&lt;sub&gt;4&lt;/sub&gt;, which was less depleted &lt;sup&gt;13&lt;/sup&gt;C in the emitted plume due to a higher oxidation rate. Methane oxidation, estimated from the isotope fractionation, ranged from 3 to 27%, with mean values of 7% and 15% for active and closed landfills, respectively. These results indicate that the oxidation rate is highly site specific.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Fundamentals of SiC-Based Device Processing

MRS Bulletin ◽  
1997 ◽  
Vol 22 (3) ◽  
pp. 42-49 ◽  
Author(s):  
M.R. Melloch ◽  
J.A. Cooper ◽  
D.J. Larkin
Keyword(s):  
Integrated Circuits ◽  
Metal Oxide ◽  
Oxidation Rate ◽  
Field Effect Transistors ◽  
Metal Oxide Semiconductor ◽  
Processing Technology ◽  
Oxide Semiconductor ◽  
Processing Technologies ◽  
Oxidation Rates ◽  
Polysilicon Gate

Since the commercial availability of SiC substrates in 1990, SiC processing technology has advanced rapidly. There have been demonstrations of monolithic digital and analogue integrated circuits, complementary metal-oxide-semiconductor (CMOS) analog integrated circuits, nonvolatile random-access memories, self-aligned polysilicon-gate metal-oxide-semiconductor field-effect transistors (MOSFETs), and buried-channel polysilicon-gate charge-coupled devices (CCDs). In this article, we review processing technologies for SiC.OxidationA beneficial feature of SiC processing technology is that SiC can be thermally oxidized to form SiO2. When a thermal oxide of thickness x is grown, 0.5x of the SiC surface is consumed, and the excess carbon leaves the sample as CO. Shown in Figure 1 are the oxide thicknesses as a function of time for the Si-face and the C-face of 6H-SiC, and for Si. The oxidation rates are considerably lower for SiC than for Si. The oxidation rate of the C-face of 6H-SiC is considerably greater than that of the Si-face. Hornetz et al. have shown that the reason for the slower oxidation rate of the Si-face is due to a 1-nm Si4C4−xO2 (x < 2) layer that forms between the SiC and the SiO2 during oxidation of the Si-face. When oxidizing the Si-face, the Si atoms oxidize first, which inhibits the oxidation of the underlying C atoms that are 0.063 nm below the Si atoms. When oxidizing the C-face, the C atoms readily oxidize first to form CO, with no formation of the Si4C4−xO2 layer for temperatures above 1000°C.

scholarly journals Comparison of the Postprandial Metabolic Fate of U- 13 C Stearic Acid and U- 13 C Oleic Acid in Postmenopausal Women

2020 ◽  
Vol 40 (12) ◽  
pp. 2953-2964
Author(s):  
Jose Rodríguez-Morató ◽  
Jean Galluccio ◽  
Gregory G. Dolnikowski ◽  
Alice H. Lichtenstein ◽  
Nirupa R. Matthan
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acid ◽  
Postmenopausal Women ◽  
Oxidation Rate ◽  
Ldl Cholesterol ◽  
Area Under The Curve ◽  
Density Lipoprotein ◽  
Plasma Metabolites ◽  
Acid Oxidation ◽  
Oxidation Rates

Objective: Compare the postprandial fatty acid metabolism of isotopically labeled stearate (U- 13 C18:0) and oleate (U- 13 C18:1). Approach and Results: In conjunction with a randomized-controlled crossover trial, 6 hypercholesterolemic postmenopausal women (≥50 years; body mass index: 25.6±3.0 kg/m 2 ; LDL [low-density lipoprotein]-cholesterol ≥110 mg/dL) consumed isocaloric diets enriched in 18:0 or 18:1 (10%–15% E) for 5 weeks each. On day 1 of week 5, following a 12-hour fast, participants receive their experimental diet divided into 13 hourly meals beginning at 8 am . U- 13 C18:0 or U- 13 C18:1 was incorporated into the 1:00 pm meal (1.0 mg/kg body weight). Serial blood and breath samples were collected over 12 hours and fasting samples at 24 and 48 hours. Plasma and lipid subfraction fatty acid profiles were assessed by gas chromatography-flame ionization detector, isotope-enrichment by liquid chromatography time-of-flight mass spectrometry, and fatty acid oxidation rate (expired 13 CO 2 ) by isotope ratio mass spectrometry. Both diets resulted in similar plasma LDL-cholesterol concentrations. Kinetic curves showed that U- 13 C18:0 had a higher plasma area under the curve (66%), lower plasma clearance rate (−46%), and a lower cumulative oxidation rate (−34%) than U- 13 C18:1. Three labeled plasma metabolites of U- 13 C18:0 were detected: 13 C16:0, 13 C16:1, and 13 C18:1. No plasma metabolites of U- 13 C18:1 were detected within the study time-frame. Higher incorporation of 18:0 in cholesteryl ester and triglyceride fractions was observed on the 18:0 compared with the 18:1 diet. Conclusions: The neutrality of 18:0 on plasma LDL-cholesterol concentrations is not attributable to a single factor. Compared with 18:1, 18:0 had higher plasma area under the curve because of lower clearance and oxidation rates, underwent both a direct and a multistage conversion to 18:1, and was preferentially incorporated into cholesteryl esters and triglycerides.

scholarly journals Effect of Oxidation Rate and Fe(II) State on Microbial Nitrate-Dependent Fe(III) Mineral Formation

2005 ◽  
Vol 71 (11) ◽  
pp. 7172-7177 ◽  
Author(s):  
John M. Senko ◽  
Thomas A. Dewers ◽  
Lee R. Krumholz
Keyword(s):  
Oxidation Rate ◽  
Sequence Similarity ◽  
Klebsiella Oxytoca ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
16S Rrna Sequence ◽  
X Ray ◽  
Oxidation Rates ◽  
Reducing Conditions

ABSTRACT A nitrate-dependent Fe(II)-oxidizing bacterium was isolated and used to evaluate whether Fe(II) chemical form or oxidation rate had an effect on the mineralogy of biogenic Fe(III) (hydr)oxides resulting from nitrate-dependent Fe(II) oxidation. The isolate (designated FW33AN) had 99% 16S rRNA sequence similarity to Klebsiella oxytoca. FW33AN produced Fe(III) (hydr)oxides by oxidation of soluble Fe(II) [Fe(II)sol] or FeS under nitrate-reducing conditions. Based on X-ray diffraction (XRD) analysis, Fe(III) (hydr)oxide produced by oxidation of FeS was shown to be amorphous, while oxidation of Fe(II)sol yielded goethite. The rate of Fe(II) oxidation was then manipulated by incubating various cell concentrations of FW33AN with Fe(II)sol and nitrate. Characterization of products revealed that as Fe(II) oxidation rates slowed, a stronger goethite signal was observed by XRD and a larger proportion of Fe(III) was in the crystalline fraction. Since the mineralogy of Fe(III) (hydr)oxides may control the extent of subsequent Fe(III) reduction, the variables we identify here may have an effect on the biogeochemical cycling of Fe in anoxic ecosystems.

Exogenous carbohydrate oxidation from different carbohydrate sources during exercise

1993 ◽  
Vol 75 (5) ◽  
pp. 2168-2172 ◽  
Author(s):  
W. H. Saris ◽  
B. H. Goodpaster ◽  
A. E. Jeukendrup ◽  
F. Brouns ◽  
D. Halliday ◽  
...  
Keyword(s):  
Physical Properties ◽  
Oxidation Rate ◽  
Corn Starch ◽  
Work Output ◽  
Cycling Exercise ◽  
Oxidation Rates ◽  
Maximum Work ◽  
The Mean ◽  
13C Tracer ◽  
Maximum Work Output

The exogenous carbohydrate (CHO) oxidation of naturally enriched [13C]CHO sources with different solubilities was studied during cycling exercise (150 min, 60% maximum work output). Moreover, the effect of adding a 13C tracer with different physical properties than the tracee on exogenous CHO oxidation was investigated. Test solutions (28.5 ml/kg body wt) were water for control of 13C background, 15% soluble partially hydrolyzed corn starch (SOL), 15% insoluble corn starch (In-SOL), and 15% InSOL with [13C6]glucose as tracer. Both the mean and peak exogenous oxidation rates were significantly greater (P < 0.05) in the SOL trial than in the InSOL trial (mean oxidation rate, 0.84 +/- 0.21 and 0.50 +/- 0.15 g/min, respectively; peak oxidation rate, 1.10 +/- 0.18 and 0.81 +/- 0.25 g/min, respectively). The amount of the ingested CHO that was oxidized was significantly higher (P < 0.05) in the SOL trial (126 +/- 31 g) than in the InSOL trial (75 +/- 25 g). When we added an extrinsic tracer ([13C]glucose), the apparent mean and peak oxidation rates of the trial with InSOL and [13C6]glucose were significantly (P < 0.05) higher (0.91 +/- 0.30 and 1.23 +/- 0.41, respectively) than the InSOL values. These results 1) indicate that the addition of the soluble [13C]glucose tracer to an insoluble starch tracee leads to overestimation of the exogenous CHO oxidation rates and 2) suggest that soluble CHO is oxidized at a higher rate during exercise than isocaloric insoluble CHO.

Oxidation rates of orally ingested carbohydrates during prolonged exercise in men

1993 ◽  
Vol 75 (6) ◽  
pp. 2774-2780 ◽  
Author(s):  
A. J. Wagenmakers ◽  
F. Brouns ◽  
W. H. Saris ◽  
D. Halliday
Keyword(s):  
Oxidation Rate ◽  
Prolonged Exercise ◽  
Work Load ◽  
Cycle Ergometer ◽  
Total Carbohydrate ◽  
Warm Up ◽  
Oxidation Rates ◽  
All Solutions ◽  
Glucose Polymer ◽  
S Oxidation

Six male volunteers exercised on a cycle ergometer at 65% of maximal work load for 120 min on six occasions while ingesting water (W) only, four doses of maltodextrin (M) [0.92, 1.85, 2.77, and 3.70 g/kg body wt (4, 8, 12, and 16% M, respectively)], and sucrose (S) [1.85 g/kg body wt (8% S)]. Drinks were given during warm-up (8 ml/kg body wt) and each 15 min during exercise (2 ml/kg body wt). M and S were of high 13C natural abundance. Total carbohydrate (CHO) and fat oxidations were calculated from the nonprotein respiratory exchange ratio. M and S increased total CHO oxidation compared with W; no difference was observed between CHO solutions. Total CHO oxidation decreased continuously with time and more rapidly after W than after M or S. Fat oxidation increased continuously in all treatments. Oxidation rates of ingested CHO were 52 +/- 19, 76 +/- 12, 86 +/- 10, and 91 +/- 9 g/2 h for 4, 8, 12, and 16% M, respectively. The oxidation rate of S was 81 +/- 10 g/2 h (not different from 8% M), which indicated that the glucose polymer had no advantage over S. Oxidation rates of M and S increased to a plateau after 90–120 min of exercise. For all solutions except 4% M, the plateau oxidation rate was close to 1.0 g/min. Differences between 8, 12, and 16% M and 8% S were minimal such that ingestion of 8% M or S may well have had an optimal ergogenic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

ELEMENTAL SULFUR OXIDATION AS INFLUENCED BY PLANT GROWTH AND DEGREE OF DISPERSION WITHIN SOIL

1990 ◽  
Vol 70 (3) ◽  
pp. 499-502 ◽  
Author(s):  
H. H. JANZEN
Keyword(s):  
Plant Growth ◽  
Key Words ◽  
Oxidation Rate ◽  
Elemental Sulfur ◽  
Sulfur Oxidation ◽  
Particle Dispersion ◽  
Controlled Environment ◽  
Oxidation Rates ◽  
S Oxidation ◽  
Elemental Sulfur Oxidation

Controlled environment studies were conducted to characterize the effects of cropping treatment and degree of particle dispersion on S oxidation rate. In two soils (a Chernozem and a Luvisol), S oxidation rates were not greatly affected by cropping treatment (barley, beans, canola, or fallow). In a second experiment, S oxidation was shown to approach maximum rates at a dispersion level of 1000 g soil g−1 S. Key words: Sulfur, placement, rhizosphere, fertilizer, elementals

Comparison of AlGaAs Oxidation in MBE and MOCVD Grown Samples

2001 ◽  
Vol 692 ◽  
Author(s):  
Y. Chen ◽  
A. Roshko ◽  
K. A. Bertness ◽  
D. W. Readey ◽  
A. A. Allerman ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Thermal Oxidation ◽  
Oxidation Rate ◽  
Oxidation Rates ◽  
Growth Method

AbstractSimultaneous wet-thermal oxidation of MBE and MOCVD grown AlxGa1−xAs layers (× = 0.1 to 1.0) showed that the epitaxial growth method does not influence the oxidation rate. Nearly identical oxidation depths were measured for samples grown by both techniques. It was found, however, that the oxidation rate is very sensitive to non-uniformities in the Al concentration in the AlxGa1−xAs layers, and that maintaining consistent and uniform Al concentrations is critical to achieving reproducible oxidation rates. The study also showed that the oxidation rate was not affected by the V/III ratio during growth nor by impurities at concentrations less than or equal to 10 ppm.

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