Nitrate Reduction by in-situ Bio-Denitrification in Groundwater

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1493-1502 ◽  
Author(s):  
M. F. Dahab ◽  
P. Y. Lee
Keyword(s):  
Nitrate Concentration ◽  
Preliminary Investigation ◽  
Nitrate Removal ◽  
Biological Factors ◽  
High Carbon ◽  
Aquifer System ◽  
High Carbon Concentration ◽  
High Head ◽  
Potential Interactions

This paper reports the results of a preliminary investigation designed to assess the potential of using in-situ bio-denitrification to reduce nitrate concentration in contaminated groundwater. The main objectives were to identify problems that may be expected to arise in in-situ groundwater denitrification; study chemical, physical and biological factors controlling subsurface bio-denitrification; and evaluate the effects of biological reactions on the resulting groundwater quality. Results confirm the technical feasibility of using in-situ nitrate removal. The relative stability of denitrification performance was observed at high carbon concentration (C:N=1.5), providing a maximum nitrate removal efficiency of 80%. The proliferation of biomass profoundly affected the potential interactions of contaminants and microorganism in subsurface region. Relatively high solids accumulation in the vicinity of the wells and their nearby aquifer matrix caused severe clogging problems and created high head-loss in the aquifer system.

In situ Biological Groundwater Denitrification: Concepts and Preliminary Field Tests

1988 ◽  
Vol 20 (3) ◽  
pp. 197-209 ◽  
Author(s):  
A. Mercado ◽  
M. Libhaber ◽  
M. I. M. Soares
Keyword(s):  
Nitrate Concentration ◽  
Nitrate Removal ◽  
Small Diameter ◽  
Field Tests ◽  
Economic Feasibility ◽  
Injection Well ◽  
Nitrate Content ◽  
Injection Wells ◽  
Protection Measures

High nitrate concentration presents the main groundwater quality problem of the Israeli coastal aquifer which supplies 25% of the total water consumption of the country. In about 50% of the coastal wells nitrate concentration exceeds 45 mg/l and in 18% of the wells nitrate concentration is above the maximum permissible concentration of the new Israeli standard - 70 mg/l. Although several protection measures, mainly administrative, were introduced, their impact would be pronounced only after 1-3 decades, thus nitrate removal technologies should be introduced as a mid-term solution. Pilot plant experiments were conducted in order to develop, demonstrate and compare various in-situ schemes for nitrate removal from groundwater by biological denitrification. Activities were focused towards two schemes: (i) Denitrification in a dual purpose (recharge-pumping) well and (ii) Substrate injection through a battery of small diameter wells surrounding a central production well (the “Daisy” system). Experiments related to the first scheme indicate that, though nitrate content can be reduced almost to zero, its economic feasibility seems to be unfavorable because of operational difficulties and the apparent requirements for costly supplementary treatment. Experiments related to the “Daisy” scheme demonstrated a nitrate removal efficiency of approximately 10%. Considering the fact that only one injection well of the three drilled functioned properly, the above mentioned nitrate removal represents the efficiency of a single injection well. It is anticipated that further experiments with the “Daisy” system consisting of 5-6 injection wells would result in a significant nitrate reduction.

Microstructure and Wear Behavior of High-Carbon Concentration CrCoNi Multi-principal Element Alloys

2021 ◽  
Author(s):  
Gustavo Bertoli ◽  
Guilherme Y. Koga ◽  
Fernanda C. Puosso ◽  
Amy J. Clarke ◽  
Claudio S. Kiminami ◽  
...  
Keyword(s):  
Carbon Concentration ◽  
Wear Behavior ◽  
High Carbon ◽  
Principal Element ◽  
High Carbon Concentration

Effects of Carbon Concentration Upon Oxygen Precipitation in Cz Si

1987 ◽  
Vol 104 ◽  
Author(s):  
S. Hahn ◽  
M. Arst ◽  
K. N. Ritz ◽  
S. Shatas ◽  
H. J. Stein ◽  
...  
Keyword(s):  
Carbon Content ◽  
Carbon Concentration ◽  
High Carbon ◽  
High Carbon Content ◽  
Oxygen Precipitation ◽  
Oxygen Precipitate ◽  
High Carbon Concentration ◽  
Precipitation Characteristics ◽  
C Complex ◽  
Oxide Precipitate

ABSTRACTEffects of high carbon concentration upon oxygen precipitate formation in Cz silicon have been investigated by combining various furnace and rapid thermal annneals. Even though oxide precipitate density increases with increasing carbon levels, Cs, synchrotron radiation section topographs of processed high carbon content wafers (Cs ∼ 4ppma) exhibit Pendellosung fringes, indicating a strain free bulk state. Our optical microscopic data have also shown very few defect etch features inside the bulk. A model based upon a direct coupling of both SiO2 and Si-C complex formation reactions is used to explain rather unique oxygen precipitation characteristics in the high carbon content Cz Si materials.

Experimental study on tensile deformation process of graphitized high carbon steel sheet

2021 ◽  
Vol 4 ◽  
pp. 74-80
Author(s):  
Zhang Yong Jun ◽  
◽  
Li Xin Peng ◽  
Wang Jiu Hua ◽  
Han Jing Tao ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Carbon Steel ◽  
Steel Sheet ◽  
Tensile Deformation ◽  
High Carbon Steel ◽  
Ferrite Matrix ◽  
High Carbon ◽  
Graphite Inclusion ◽  
Carbon Steel Sheet

As the object for the study, graphitized high-carbon steel sheet with a carbon content of 0.66 % was used, the tensile test of this sheet using a universal testing (breaking) machine was performed; as well as in-situ observation of the microstructure in the process of tensile deformation of this sheet using in-situ technology of scanning electron microscopy (SEM) was made. The test results show that the main mechanical properties in different directions of tested graphitized high-carbon steel sheet are relatively the same, that is, for a tensile sample of different directions, the ratio of the yield strength σ0,2 to the tensile strength σв is approximately 0.73; the strain hardening index n is approximately 0.24; the plastic deformation coefficient r is approximately 0.83. This indicates that this sheet did not exhibit significant anisotropy. In the process of tensile, deformation of the specimen is mainly developed from local plastic deformation of the graphite inclusions to the total deformation in the deformation zone of the sample; with the increase of displacement, micro-gap between the graphite inclusion and ferrite grain along the direction of the axis of tensile gradually formed and propagated along the direction perpendicular to the axis of tensile; number of slip lines in the ferrite matrix gradually increased, and the distance between them gradually decreases; when the sample breaks, in the fracture large dimple with the core of graphite inclusion and small dimples in the ferrite appears. And the ferrite matrix near the fracture is covered with slip lines, this shows that the ferritic matrix underwent severe plastic deformation before breaking.

scholarly journals Performance of a triple-GEM demonstrator in pp collisions at the CMS detector

2021 ◽  
Vol 16 (11) ◽  
pp. P11014
Author(s):  
M. Abbas ◽  
M. Abbrescia ◽  
H. Abdalla ◽  
A. Abdelalim ◽  
S. AbuZeid ◽  
...  
Keyword(s):  
Hadron Collider ◽  
Preliminary Investigation ◽  
Operational Experience ◽  
Detector Performance ◽  
Proton Proton ◽  
Background Rate ◽  
Electron Multiplier ◽  
Gem Detector ◽  
Gem Detectors

Abstract After the Phase-2 high-luminosity upgrade to the Large Hadron Collider (LHC), the collision rate and therefore the background rate will significantly increase, particularly in the high η region. To improve both the tracking and triggering of muons, the Compact Muon Solenoid (CMS) Collaboration plans to install triple-layer Gas Electron Multiplier (GEM) detectors in the CMS muon endcaps. Demonstrator GEM detectors were installed in CMS during 2017 to gain operational experience and perform a preliminary investigation of detector performance. We present the results of triple-GEM detector performance studies performed in situ during normal CMS and LHC operations in 2018. The distribution of cluster size and the efficiency to reconstruct high pT muons in proton-proton collisions are presented as well as the measurement of the environmental background rate to produce hits in the GEM detector.

Comparison of denitrification performances using PLA/starch with different mass ratios as carbon source

2015 ◽  
Vol 71 (7) ◽  
pp. 1019-1025 ◽  
Author(s):  
Chuanfu Wu ◽  
Danqi Tang ◽  
Qunhui Wang ◽  
Juan Wang ◽  
Jianguo Liu ◽  
...  
Keyword(s):  
Carbon Source ◽  
Groundwater Remediation ◽  
Nitrate Concentration ◽  
Starch Content ◽  
Nitrate Removal ◽  
Carbon Sources ◽  
National Standard ◽  
Biofilm Carrier ◽  
Carbon Release ◽  
Biological Nitrate Removal

A suitable carbon source is significant for biological nitrate removal from groundwater. In this study, slow-release carbon sources containing polylactic acid (PLA) and starch at 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 ratios were prepared using a blending and fusing technique. The PLA/starch blend was then used as a solid carbon source for biological nitrate removal. The carbon release rate of PLA/starch was found to increase with increased starch content in leaching experiments. PLA/starch at 5:5 mass ratio was found to have the highest denitrification performance and organic carbon consumption efficiency in semi-continuous denitrification experiments, and was also revealed to support complete denitrification at 50 mg-N/L influent nitrate concentration in continuous experiments. The effluent nitrate concentration was <2 mg NO3–-N/L, which met the national standard (GB 14848-93) for groundwater. Scanning electron microscopy results further showed that the surface roughness of PLA/starch increased with prolonged experimental time, which may be conducive to microorganism attachment. Therefore, PLA/starch was a suitable carbon source and biofilm carrier for groundwater remediation.

scholarly journals A Study on the Mechanism and Kinetic of Nitrate Reduction by the nZVI-g-C3N4/TiO2  Composite Under the Simulated Sunlight

2021 ◽  
Author(s):  
Linyu Wei ◽  
Jing Tian ◽  
Qing Wang ◽  
Yuanyuan Liu ◽  
Yi Yu ◽  
...  
Keyword(s):  
Nitrate Reduction ◽  
Reduction Method ◽  
Nitrate Removal ◽  
Simulated Sunlight ◽  
Photoelectric Properties ◽  
Phase Reduction ◽  
Reduction Efficiency ◽  
Initial Ph ◽  
Lamp System

Abstract g-C3N4/TiO2 composite has excellent photoelectric properties and is considered as a good carrier of nanoparticles. A novel composite of nZVI-g-C3N4/TiO2 was successfully synthesized through in-situ growth nZVI on the surface of g-C3N4/TiO2 with liquid phase reduction method. The composite was characterized by TEM, XRD, EDS and evaluated its nitrate removal efficiency. The effects of composite dosage, solution initial pH and HCOOH concentration on nitrate reduction were investigated. The results showed that nitrate was rapidly reduced by nZVI-g-C3N4/TiO2 composite. The dosage of 4 g/L nZVI-g-C3N4/TiO2 composite and 3.0 mM of HCOOH concentration was more suitable for nitrate reduction. Solution initial pH had little impact on the nitrate reduction efficiency, but affected the proportion of the nitrate reduction products. The mechanism of nitrate reduction in the nZVI-gC3N4/TiO2/HCOOH-Xe-lamp system was proposed. The nZVI-gC3N4/TiO2 composite could be considered as a viable and promising technology for water pollution remediation.

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