Characterization of platinum alloy used in ammonia oxidation. Morphology and microstructure of Pt–Pd–Rh–Ru gauzes after the oxidation of NH3 with air at 1133 K

2021 ◽  
pp. 125138
Author(s):  
Aleksei N. Salanov ◽  
Alexandra N. Serkova ◽  
Natalya M. Chesnokova ◽  
Lyubov A. Isupova ◽  
Valentin N. Parmon
Keyword(s):  
Ammonia Oxidation ◽  
Platinum Alloy

Characterization of catalyst and catchment gauzes used in medium- and low-pressure ammonia oxidation plants

1992 ◽  
Vol 27 (3) ◽  
pp. 685-691 ◽  
Author(s):  
J. L. G. Fierro ◽  
J. M. Palacios ◽  
F. Tomas
Keyword(s):  
Ammonia Oxidation ◽  
Low Pressure

scholarly journals Ecophysiological Characterization of Ammonia-Oxidizing Archaea and Bacteria from Freshwater

2012 ◽  
Vol 78 (16) ◽  
pp. 5773-5780 ◽  
Author(s):  
Elizabeth French ◽  
Jessica A. Kozlowski ◽  
Maitreyee Mukherjee ◽  
George Bullerjahn ◽  
Annette Bollmann
Keyword(s):  
Growth Rates ◽  
Ammonia Oxidation ◽  
Light Exposure ◽  
Enrichment Culture ◽  
Ammonia Oxidizing Bacteria ◽  
Content Type ◽  
Ammonia Oxidizing Archaea ◽  
Group I ◽  
Nitrosomonas Oligotropha

ABSTRACTAerobic biological ammonia oxidation is carried out by two groups of microorganisms, ammonia-oxidizing bacteria (AOB) and the recently discovered ammonia-oxidizing archaea (AOA). Here we present a study using cultivation-based methods to investigate the differences in growth of three AOA cultures and one AOB culture enriched from freshwater environments. The strain in the enriched AOA culture belong to thaumarchaeal group I.1a, with the strain in one enrichment culture having the highest identity with “CandidatusNitrosoarchaeum koreensis” and the strains in the other two representing a new genus of AOA. The AOB strain in the enrichment culture was also obtained from freshwater and had the highest identity to AOB from theNitrosomonas oligotrophagroup (Nitrosomonascluster 6a). We investigated the influence of ammonium, oxygen, pH, and light on the growth of AOA and AOB. The growth rates of the AOB increased with increasing ammonium concentrations, while the growth rates of the AOA decreased slightly. Increasing oxygen concentrations led to an increase in the growth rate of the AOB, while the growth rates of AOA were almost oxygen insensitive. Light exposure (white and blue wavelengths) inhibited the growth of AOA completely, and the AOA did not recover when transferred to the dark. AOB were also inhibited by blue light; however, growth recovered immediately after transfer to the dark. Our results show that the tested AOB have a competitive advantage over the tested AOA under most conditions investigated. Further experiments will elucidate the niches of AOA and AOB in more detail.

Ammonia removal in the catalytic wet air oxygen process of landfill leachates with Co/Bi catalyst

2006 ◽  
Vol 54 (8) ◽  
pp. 147-154 ◽  
Author(s):  
Y. Li ◽  
L. Liu ◽  
G.H. Huang ◽  
L. Zhu
Keyword(s):  
Ammonia Oxidation ◽  
Molecular Nitrogen ◽  
Ammonia Removal ◽  
Air Oxidation ◽  
X Ray Diffraction ◽  
Landfill Leachates ◽  
System Temperature ◽  
Oxygen Process ◽  
Oxidation Of Ammonia

Oxidation of ammonia in landfill leachates in the catalytic wet air oxidation (CWAO) process was investigated with Co/Bi catalyst. The characterization of the Co/Bi catalyst was carried out by the X-ray diffraction technique. Studies of ammonia removal from the landfill leachates by CWAO showed that Co/Bi catalyst exhibited higher activities for both total organic carbon (TOC) and ammonia with removal levels of 99% for TOC and 98% for ammonia, respectively. Results also indicated that large amounts of ammonia were produced during the elimination of nitrogenous organic compounds in the CWAO process and the further oxidation of ammonia gave off essentially N2 under 240 °C. When the system temperature reached above 240 °C, ammonia oxidation rate was much higher with nitrate dominating in the effluent; a very small amount of nitrite was observed in the reaction process, it possibly acts as the intermediate of nitrate ion and molecular nitrogen formation, showing that the system temperature had significant effects on the ammonia oxidation and reaction selectivity towards the production of molecular nitrogen or nitrate.

Characterization of amoA and hao Genes Responsible for Ammonia Oxidation Reaction in CANON System

2011 ◽  
Vol 183-185 ◽  
pp. 1014-1019
Author(s):  
Hai Yan Zou ◽  
Jun Li Huang ◽  
Fang Fang ◽  
Jin Song Guo
Keyword(s):  
Nitrogen Removal ◽  
Oxidation Reaction ◽  
High Efficiency ◽  
Ammonia Oxidation ◽  
Residual Activity ◽  
Maximum Activity ◽  
Ammonia Oxidizing Bacteria ◽  
Hydroxylamine Oxidoreductase ◽  
Optimum Ph

In this research the genes (amoA and hao) for ammonia monooxygenase (AMO) and hydroxylamine oxidoreductase (HAO) responsible for ammonia oxidation reaction in completely autotrophic nitrogen removal over nitrite process were cloned and sequenced, and the recombinant protein of AMO and HAO was expressed and characterized. The optimum temperature for AMO activity was 55 °C and more than 40% of the maximum activity was retained from 15-50 °C. The optimum pH for the enzyme was found to be pH 11.0. The highest activity for HAO was observed at 45 °C. More than 50% of the maximum activity was retained even at 55 °C. The dependence of HAO on pH was strong and only average 15% of residual activity left at pH ranging from 3.0-9.0. Study on the molecular and biochemistry properties of recombinant AMO and HAO will benefit for the manipulation of ammonia-oxidizing bacteria to achieve the goal of high efficiency of nitrogen removal.

In-situ characterization of microbial community in an A/O submerged membrane bioreactor with nitrogen removal

2004 ◽  
Vol 50 (8) ◽  
pp. 41-48 ◽  
Author(s):  
A. Sofia ◽  
W.-T. Liu ◽  
S.L. Ong ◽  
W.J. Ng
Keyword(s):  
Bacterial Community ◽  
Nitrogen Removal ◽  
Membrane Bioreactor ◽  
Ammonia Oxidation ◽  
Paracoccus Denitrificans ◽  
Pseudomonas Stutzeri ◽  
Laboratory Scale ◽  
Negative Results

The bacterial community involved in removing nitrogen from sewage and their preferred DO environment within an anoxic/oxic membrane bioreactor (A/O MBR) was investigated. A continuously operated laboratory-scale A/O MBR was maintained for 360 d. At a sludge age of 150 d and a C/N ratio of 3.5, the system was capable of removing 88% of the influent nitrogen from raw wastewater through typical nitrogen removal transformations (i.e. aerobic ammonia oxidation and anoxic nitrate reduction). Characterization of the A/O MBR bacterial community was carried out using fluorescence in situ hybridization (FISH) techniques. FISH results further showed that Nitrosospira spp. and Nitrospira spp. were the predominant groups of ammonia and nitrite oxidizing group, respectively. They constituted up to 11% and 6% of eubacteria at DO below 0.05 mg/l (low DO), respectively, and about 14% and 9% of eubacteria at DO between 2–5 mg/l (sufficient DO), respectively, indicating preference of nitrifiers for a higher DO environment. Generally low counts of the genus Paracoccus were detected while negative results were observed for Paracoccus denitrificans, Alcaligenes spp, and Pseudomonas stutzeri under the low and sufficient DO environments. The overall results indicate that Nitrosospira spp., Nitrospira spp. and members of Paracoccus spp. can be metabolically functional in nitrogen removal in the laboratory-scale A/O MBR system.

Physiological and Molecular Biological Characterization of Ammonia Oxidation of the Heterotrophic Nitrifier Pseudomonas putida

1998 ◽  
Vol 37 (4) ◽  
pp. 281-288 ◽  
Author(s):  
Michael Daum ◽  
Wolfgang Zimmer ◽  
Hans Papen ◽  
Karin Kloos ◽  
Kerstin Nawrath ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Ammonia Oxidation ◽  
Biological Characterization
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