Optimizing Nitrification in Aeration Basins with Surface Aerators

1988 ◽  
Vol 20 (4-5) ◽  
pp. 23-28
Author(s):  
W. Maier ◽  
Kh Krauth
Keyword(s):  
Oxygen Content ◽  
Oxygen Concentration ◽  
Detailed Examination ◽  
Ammonia Nitrogen ◽  
Factors Influencing ◽  
Detailed Evaluation ◽  
Low Levels

The detailed evaluation of the data from the daily logbooks of municipal clarification plants led to the finding that the nitrification capability of the plants is in essence dependent on the BOD5- and nitrogen sludge load. The evaluation of the data showed that, above all, aeration units with surface aerators did not operate well in respect to nitrification. Comprehensive investigations of different clarification plants led to the identification of shortages in the oxygen content of the aeration basins as the main reason for these deficiencies. The detailed examination of the results of these investigations shows clearly that in order to maintain low levels of ammonia nitrogen in the effluent, more attention must be paid to the factors influencing the oxygen concentration and distribution.

scholarly journals Investigation of factors influencing oxygen content in Halobacterium salinarum growth medium for improved bacteriorhodopsin production

2019 ◽  
Vol 10 (3) ◽  
pp. 261-268 ◽  
Author(s):  
Shadi Rajab ◽  
Valiollah Babaeipour ◽  
Sirwan Khanchezar ◽  
Ghasem Amoabediny ◽  
Fatemeh Yazdian ◽  
...  
Keyword(s):  
Oxygen Content ◽  
Growth Medium ◽  
Halobacterium Salinarum ◽  
Factors Influencing

Observer Based Oxygen Fraction Estimation for a Dual-Loop EGR Diesel Engine Fueled With Biodiesel Blends

2013 ◽  
Author(s):  
Junfeng Zhao ◽  
Junmin Wang
Keyword(s):  
Oxygen Content ◽  
Oxygen Concentration ◽  
Control Unit ◽  
Intake Manifold ◽  
Engine Model ◽  
Oxygen Fraction ◽  
Emission Effect ◽  
Physical Insight ◽  
Gas Recirculation ◽  
Insight Into

This paper investigates the influence of biodiesel on the effectiveness of exhaust gas recirculation (EGR) in modern Diesel engines equipped with dual-loop EGR systems. Intake manifold oxygen fraction, which is an important factor for both combustion and emissions, is selected as a new reference for evaluating the equivalent EGR level instead of EGR ratio. A Luenberger-like observer for the oxygen fraction is designed based on the dynamic model of the air-path loop with consideration of the existence of oxygen content in the fuel. The convergence of the observer is proved with the assistance of some physical insight into the engine system. The performance of the observer is validated on a high-fidelity engine model built in GT-Power. The results show that when the same amount of fuel is injected, there is an increase in the exhaust oxygen concentration for biodiesel as oxygen content in fuel increases. Then the higher exhaust oxygen concentration leads to an increase in the intake manifold oxygen fraction, since the engine control unit (ECU) commanded EGR valve angles are constant across different fuels. This real-time oxygen fraction estimation approach is potentially useful for mitigating the biodiesel NO x emission effect.

Extrapulmonary factors influencing the ratio of arterial oxygen tension to inspired oxygen concentration in burn patients

1979 ◽  
Vol 7 (11) ◽  
pp. 492-496 ◽  
Author(s):  
J. A. JEEVENDRA MARTYN ◽  
NAOKI AIKAWA ◽  
ROGER S. WILSON ◽  
STANISLAW K. SZYFELBEIN ◽  
JOHN F. BURKE
Keyword(s):  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Arterial Oxygen Tension ◽  
Arterial Oxygen ◽  
Burn Patients ◽  
Factors Influencing ◽  
Inspired Oxygen

scholarly journals Factors Influencing Career Choice of Female Surgical Trainees

2011 ◽  
Vol 93 (3) ◽  
pp. 1-7 ◽  
Author(s):  
U Walsh ◽  
FJ Meyer
Keyword(s):  
Career Choice ◽  
Medical Graduates ◽  
Factors Influencing ◽  
Surgical Trainees ◽  
Low Levels ◽  
Considerable Body

Increasing numbers of female medical graduates and consistently low levels of female entry into some specialities such as surgery continue to spark debate and have prompted a considerable body of research.

scholarly journals Tunnel Fire Dynamics as a Function of Longitudinal Ventilation Air Oxygen Content

2019 ◽  
Vol 11 (1) ◽  
pp. 203 ◽  
Author(s):  
Sanjay Kumar Khattri ◽  
Torgrim Log ◽  
Arjen Kraaijeveld
Keyword(s):  
Oxygen Content ◽  
Oxygen Concentration ◽  
Ambient Air ◽  
Fire Dynamics ◽  
Maximum Heat ◽  
Tunnel Fire ◽  
Longitudinal Ventilation ◽  
Rate Maximum ◽  
Air Ventilation ◽  
Safety Parameters

Longitudinal ambient air ventilation is the most common methodology for maintaining an amicable environment in tunnels during normal operations while providing an evacuation path during tunnel fire emergencies. The present work investigates the influence of forced ventilation air oxygen concentrations on tunnel fire dynamics. Mixing inert gasses such as nitrogen, argon, or carbon dioxide with ambient air changes the ventilation air oxygen concentration. In order to quantify the influence of the oxygen content on the critical tunnel safety parameters, multiple computational fluid dynamics (CFD) simulations were done on a reduced-size tunnel while preserving the system Froude number. Analytical expressions were developed to describe the importance of oxygen content on the tunnel fire dynamics. By employing Froude scaling, the resulting relations were extrapolated to real scale tunnels. For the ambient air ventilation, the extrapolated expressions displayed good agreement with experimental literature data. By adjusting the oxygen concentration, parameters such as maximum tunnel ceiling temperature, fire growth rate, maximum heat flux to the tunnel floor, maximum flux on the tunnel ceiling, and maximum heat release rate can be controlled. This is the case also for oxygen levels where people can survive. This may increase the possibility for evacuation and improve the conditions for firefighting, significantly improving tunnel fire safety.

Factors Influencing Submergence and the Heart Rate in the Frog

1964 ◽  
Vol 41 (2) ◽  
pp. 417-431
Author(s):  
D. R. JONES
Keyword(s):  
Carbon Dioxide ◽  
Heart Rate ◽  
Oxygen Concentration ◽  
Carbon Dioxide Concentration ◽  
Carbon Dioxide Content ◽  
Factors Influencing ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration ◽  
Main Factors ◽  
Critical Carbon Dioxide

1. The ability of the frog to remain submerged declines as the oxygen concentration in the water falls or the carbon dioxide content rises. The critical oxygen concentration appears to be about 5 mg./l. and the critical carbon dioxide concentration 100 mg./l. at temperatures around 10° C. 2. Submergence results in a decrease in heart rate which develops over a period of 15-30 min. but which disappears immediately the animal surfaces and breathes. The bradycardia is accentuated by oxygen lack or carbon dioxide excess. 3. During submergence the heart is influenced by two main factors, the shortage of oxygen and the cessation of breathing movements, both of which contribute to the decrease in rate. The former can still affect rate after vagotomy. The connexion between breathing and heart rate is dependent on the nervous system, though the detailed pathway is not worked out.

Non-Stoichiometry and Complex Defects in the Structure of R-Ba-Cu-O Single Crystals Determined by Neutron Diffraction

1989 ◽  
Vol 169 ◽  
Author(s):  
P. Schweiss ◽  
Ph. Galez ◽  
G. Collin ◽  
F. Marucco
Keyword(s):  
Crystal Structure ◽  
Exact Solution ◽  
Neutron Diffraction ◽  
Single Crystals ◽  
Oxygen Content ◽  
Oxygen Concentration ◽  
Copper Deficiency

AbstractThe crystal structure of several RBa2Cu3-yO6+z (R=Y,Ho) crystals are investigated by neutron diffraction using an exact solution for the twinned orthorhombic samples. For an oxygen concentration >0.35 in the chains, the structure is orthorhombic due to an exclusive occupancy of the 0(4) site. A systematic and variable copper deficiency is observed on the Cu(l) site leading to a correlated defect on the chain oxygen O(4) and on the bridging oxygen O(l). Due to the presence of these defects, a transverse disorder is observed for the highest oxygen content with a residual occupancy of the forbidden O(5) site.

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