One-stage deammonification: nitrogen elimination at low costs

2001 ◽  
Vol 1 (1) ◽  
pp. 71-80 ◽  
Author(s):  
C.F. Seyfried ◽  
A. Hippen ◽  
C. Helmer ◽  
S. Kunst ◽  
K-H Rosenwinkel
Keyword(s):  
Direct Conversion ◽  
High Nitrogen ◽  
Industrial Plants ◽  
Nitrogen Loads ◽  
Operation Results ◽  
Micro Organisms ◽  
Biological Nitrogen ◽  
Nitrogen Elimination ◽  
Nitrogen Contents ◽  
Elementary Nitrogen

Biological nitrogen elimination used to purify wastewater with high nitrogen contents can become a major cost factor, in particular when the wastewater in question contains only little amounts of biologically degradable carbon compounds. The use of new biological conversion methods and the application of compact operation technology, however, does allow us to save operation and investment costs. Currently, the focus of scientific interest is on deammonification, that is the direct conversion of ammonia into elementary nitrogen by autotrophic micro-organisms, because in contrast to conventional nitrification/denitrification this method requires considerably smaller amounts not only of carbon, but also of oxygen. Moreover, the use of compact biofilm technology makes it possible to considerably reduce the reaction tank volume. In the following we will present the operation results of both industrial plants and laboratory-scale units for the treatment of wastewater with high nitrogen loads, results which unequivocally show the favourable cost-effectiveness of the mentioned method combination and thus the economic viability inherent in the purposeful industrial utilisation of this technology.

Six years' practical experience with aerobic/anoxic deammonification in biofilm systems

2001 ◽  
Vol 44 (2-3) ◽  
pp. 39-48 ◽  
Author(s):  
A. Hippen ◽  
C. Helmer ◽  
S. Kunst ◽  
K.-H. Rosenwinkel ◽  
C. F. Seyfried
Keyword(s):  
Practical Experience ◽  
Pilot Scale ◽  
High Nitrogen ◽  
Industrial Plants ◽  
Carbon Demand ◽  
Operation Stability ◽  
Operation Results ◽  
Micro Organisms ◽  
Nitrogen Elimination ◽  
Nitrogen Contents

Nitrogen elimination through autotrophic micro-organisms is currently in the focus of research projects on the treatment of wastewater with high nitrogen contents, for instance to be able to develop and fix dimensioning parameters for purposeful application. In fact, several industrial plants have already shown for some years that the steady operation of nitrogen elimination without carbon demand is possible. Due to the low growth rates of the participating micro-organisms, these processes can be found in particular in biofilm systems, which also allow for the simultaneous running of the two basic processes. In the following, we will discuss on the basis of the operation results of industrial and pilot-scale plants the operation stability of the aerobic/anoxic deammonification, and explain which experiences are available in particular for conversion in biofilm systems.

Characteristics of Dynamic Recrystallization during Hot Deformation for High Nitrogen Stainless Steels

2012 ◽  
Vol 715-716 ◽  
pp. 115-121
Author(s):  
Hai Wen Luo ◽  
Xu Dong Fang ◽  
Rui Zhen Wang ◽  
Zhan Yin Diao
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Strain Rates ◽  
Peak Strain ◽  
High Nitrogen ◽  
Flow Curves ◽  
Grain Sizes ◽  
Nitrogen Contents ◽  
High Nitrogen Stainless Steel

Dynamic recrystallization was studied for the stainless steels with nitrogen contents of 0.56% to 1.08% during hot deformation at temperatures of 900~1200 with strain rates ranging from 0.003 to 42 s-1. It was found that flow stress could increase remarkably with increasing nitrogen content. Flow curves during the deformation by 0.1~42/s at temperatures of 900~1200°C show a single peak, indicating the occurrence of dynamic recrystallization during deformation. The peak strain seems to decrease with increasing N content, suggesting that higher content of N facilitates dynamic recrystallization. The quenched microstructures were analyzed by optical microscopy, EBSD and TEM. The recrystallized grain sizes on the quenched specimens were measured and its dependence on temperature and strain rate was analyzed. At high temperature, continuously dynamically recrystallized microstructures were observed; whilst at low temperature, necklace-like partially recrystallized microstructures were found. Key words: High nitrogen stainless steel; dynamic recrystallization; stress-strain curves

La corrosion par piqûres d'aciers inoxydables austéno-ferritiques dans l'eau de mer synthétique

1996 ◽  
Vol 84 ◽  
pp. 23-30
Author(s):  
I. Trigui ◽  
H. Sidhom ◽  
C. Braham ◽  
J. Lédion
Keyword(s):  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Sea Water ◽  
Phase Behaviour ◽  
High Nitrogen ◽  
Electrochemical Tests ◽  
Analysis Techniques ◽  
Pitting Corrosion Resistance ◽  
Nitrogen Contents ◽  
Image Analysis Techniques

Duplex stainless steels crevice and pitting corrosion resistance in synthetic sea water is studied. Conventional electrochemical tests and image analysis techniques are used. Three commercial steels are examined. The forged material has the best behaviour, whereas cast materials, in spite of their high nitrogen contents, have a lower corrosion resistance. Micrographic studies show a good correlation between pittings distribution and inclusions distribution and reveal that gamma phase behaviour is more affected by inclusions. The metallurgic purity of products seems to be the most important parameter in this type of corrosion. Consequently, the PREN index is questionable in pitting corrosion grading of these steels because it does not take into acount the inclusions effect.

Tensile Fracture of the Welded Joints of Austenitic High-Nitrogen 05Kh22AG16N8M Steel with Various Nitrogen Contents

2021 ◽  
Vol 2021 (10) ◽  
pp. 1299-1303
Author(s):  
V. M. Blinov ◽  
E. I. Lukin ◽  
E. V. Blinov ◽  
M. A. Samoilova
Keyword(s):  
Welded Joints ◽  
Tensile Fracture ◽  
High Nitrogen ◽  
Nitrogen Contents

Effect of Heat Treatment on TiNx Film Structure

2005 ◽  
Vol 480-481 ◽  
pp. 187-192
Author(s):  
S. Zerkout ◽  
M. Benkahoul ◽  
H. Sahraoui ◽  
S. Achour ◽  
A. Mosser
Keyword(s):  
Heat Treatment ◽  
Nitrogen Content ◽  
Thermal Instability ◽  
Lattice Parameter ◽  
Film Structure ◽  
High Nitrogen Content ◽  
High Nitrogen ◽  
Tin Films ◽  
Film Instability ◽  
Nitrogen Contents

TiN films with different nitrogen contents were deposited on glass and Si (100) substrates by d. c. magnetron reactive sputtering. The structure of the films was determined by Xray diffraction. It was found that heat treatment at 773 decreased the lattice parameter. A considerable thermal instability of over-stoichiometric films was observed after annealing films in air. This instability enhanced with increasing nitrogen content and is characterized by an abundant appearance of clear and dark disks in Scanning Electron Microscopy (SEM). Also, it was shown that the film instability does not come from an interfacial reaction but was observed when the TiNx layers present a (200) preferred orientation together with high nitrogen content.

Biological and ecological aspects of nitrogen fixation by free-living micro-organisms

1969 ◽  
Vol 172 (1029) ◽  
pp. 367-388 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Soil Fertility ◽  
Biological Nitrogen Fixation ◽  
Higher Plants ◽  
Symbiotic Association ◽  
Free Living ◽  
Blue Green Algae ◽  
Ecological Aspects ◽  
Micro Organisms ◽  
Biological Nitrogen

Biological nitrogen fixation is a characteristic of certain micro-organisms, which may be free-living or occur in symbiotic association with higher plants. The purpose of this paper is to summarize some of the biological and ecological aspects of nitrogen-fixation by free-living forms. Biochemical aspects have been reviewed in other contributions to this discussion by Drs Wilson, Burris, and Cox & Fay. Nitrogen fixation by heterotrophic micro-organisms has been considered by Jensen (1965); nitrogen fixation by blue-green algae by Fogg & Stewart (1965), and by Stewart (1966, 1969), while Moore (1966) has evaluated the contribution of nitrogen-fixing micro-organisms to soil fertility.

?-TaN as a Reference Material for the Determination of High Nitrogen Contents

2004 ◽  
Vol 146 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Wolfgang Gruner ◽  
Birgit Wollein ◽  
Walter Lengauer
Keyword(s):  
Reference Material ◽  
High Nitrogen ◽  
Nitrogen Contents

Use of the15N natural abundance technique for the quantification of the contribution of N2 fixation to sugar cane and other grasses

2001 ◽  
Vol 28 (9) ◽  
pp. 889 ◽  
Author(s):  
Robert M. Boddey ◽  
José Carlos Polidoro ◽  
Alexander S. Resende ◽  
Bruno J. R. Alves ◽  
Segundo Urquiaga
Keyword(s):  
Nitrogen Fixation ◽  
Sugar Cane ◽  
Sampling Strategy ◽  
Natural Abundance ◽  
Isotopic Abundance ◽  
Natural Ecosystems ◽  
Reference Plants ◽  
Micro Organisms ◽  
Biological Nitrogen ◽  
15N Abundance

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000 The use of the 15N natural abundance technique to quantify contribution of biological nitrogen fixation (BNF) to any plant is based on the observation that N derived from soil is generally slightly different [usually higher in 15N abundance (δ15N‰)] than that of the air. Plants or micro-organisms growing solely on BNF generally accumulate N with 15N isotopic abundance lower than that of the air (i.e. δ15N‰ is negative), while plants obtaining all N from the soil generally show a positive δ15N‰ signal. The technique is applied by estimating the 15N abundance of the putative ‘N2-fixing’ crop and analysing the 15N abundance of neighbouring non-N2-fixing reference plants. However, often there are such large variations in the N derived from the soil by different non-N2-fixing plants that in natural ecosystems it is often impossible to even distinguish plants that are benefiting form BNF, let alone quantity this contribution. The reasons why soil derived N can vary so widely, especially in natural ecosystems, are briefly discussed and a sampling strategy is described to assess possible BNF inputs to sugar cane plants in commercial plantations in Brazil. The results suggest that in nine of the 11 sites studied, BNF inputs were significant ranging from 25 to 60% of N assimilated.

Mesoporous nitrogen-doped carbons with high nitrogen contents and ultrahigh surface areas: synthesis and applications in catalysis

2016 ◽  
Vol 18 (7) ◽  
pp. 1976-1982 ◽  
Author(s):  
Zhishuang Ma ◽  
Hongye Zhang ◽  
Zhenzhen Yang ◽  
Guipeng Ji ◽  
Bo Yu ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Aqueous Phase ◽  
High Efficiency ◽  
High Nitrogen Content ◽  
High Nitrogen ◽  
Nitrogen Doped ◽  
Surface Areas ◽  
Nitrogen Contents

Mesoporous nitrogen-doped carbons with high nitrogen content and ultrahigh surface areas were prepared, which showed high efficiency for oxidation of alkanes in aqueous phase.

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