scholarly journals Improvement of Oxygen Transfer Efficiency in Diffused Aeration Systems Using Liquid-Film-Forming Apparatus

10.5772/22908 ◽  
2011 ◽  
Author(s):  
Tsuyoshi Imai ◽  
Hua Zhu
Keyword(s):  
Liquid Film ◽  
Oxygen Transfer ◽  
Transfer Efficiency ◽  
Film Forming ◽  
Oxygen Transfer Efficiency

Enhancement of Oxygen Transfer Efficiency in Diffused Aeration Systems using Liquid-Film-Forming Apparatus

2007 ◽  
Vol 28 (5) ◽  
pp. 511-519 ◽  
Author(s):  
H. Zhu ◽  
T. Imai ◽  
K. Tani ◽  
M. Ukita ◽  
M. Sekine ◽  
...  
Keyword(s):  
Liquid Film ◽  
Oxygen Transfer ◽  
Transfer Efficiency ◽  
Film Forming ◽  
Oxygen Transfer Efficiency

Improvement of oxygen transfer efficiency in aerated ponds using liquid-film-assisted approach

2007 ◽  
Vol 55 (11) ◽  
pp. 183-191 ◽  
Author(s):  
H. Zhu ◽  
T. Imai ◽  
K. Tani ◽  
M. Ukita ◽  
M. Sekine ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Transfer ◽  
Structural Parameters ◽  
Volumetric Mass Transfer Coefficient ◽  
Aeration System ◽  
Film Forming ◽  
Oxygen Transfer Efficiency

In aerated ponds, oxygen is generally supplied through either diffused or mechanical aeration means. Surface transfer and bubble transfer both contribute significantly to oxygen transfer in a diffused aeration system. In the present study, a liquid-film-forming apparatus (LFFA) is successfully developed on a laboratory scale to improve considerably the surface transfer via the unique liquid film transfer technique. The experimental results show that the volumetric mass transfer coefficient for LFFA alone is found to be as much as 5.3 times higher than that for water surface and that the total volumetric mass transfer coefficient for the liquid film aeration system increases by 37% in comparison with a conventional aeration system. Additionally, by tuning finely the structural parameters of the LFFA, it can also lead to high dissolved oxygen (DO) water with the DO percent saturation greater than 90%. More importantly, this result is accomplished by simply offering a single-pass aeration at a depth as shallow as 26 cm. As a result, the objective of economical energy consumption in aerated ponds can be realized by lowering the aeration depth without sacrificing the aeration efficiency. It is noteworthy that the data presented in this study are acquired either numerically or experimentally.

The Effect of Nozzle Type on Air Entrainment by Plunging Water Jets

2002 ◽  
Vol 37 (3) ◽  
pp. 599-612 ◽  
Author(s):  
Tamer Bagatur ◽  
Ahmet Baylar ◽  
Nusret Sekerdag
Keyword(s):  
Penetration Depth ◽  
Oxygen Transfer ◽  
Free Water ◽  
Air Entrainment ◽  
Water Jet ◽  
Transfer Efficiency ◽  
Entrainment Rate ◽  
Water Jets ◽  
Air Entrainment Rate ◽  
Oxygen Transfer Efficiency

Abstract In this study, for the plunging water jet aeration system using various inclined nozzle types, bubble penetration depth, air entrainment rate, water jet expansion, effect of water jet circumference at impact point, oxygen transfer coefficient and oxygen transfer efficiency which changed depending on the water jet velocity, were researched in an air-water system. Numerous studies were conducted with circular nozzles. The present study describes new experiments performed with different nozzle types. Three types of nozzles were examined, i.e., those with circular, ellipse and rectangle duct with rounded ends. Experimental results showed that water jets produced with ellipse and rectangle duct with rounded ends nozzles have very different flow characteristics, entrainment patterns on free water jet surface, and submerged water jet region within the receiving tank. Higher air entrainment rate and oxygen transfer efficiency was observed in the rectangle duct with rounded ends nozzle due to water jet expansion. Bubble penetration depth, however, is lower for the rectangle duct with rounded ends nozzle than for the other nozzles. The ellipse nozzle provided the highest bubble penetration depth. These results showed that it is appropriate to use ellipse nozzle in aeration of deep pool and rectangle duct with rounded ends nozzle in the applications where high bubble concentration is desirable.

Oxygen Transfer Efficiency Measurements Using Off-Gas Techniques

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1295-1300 ◽  
Author(s):  
W. C. Boyle ◽  
B. G. Hellstrom ◽  
L. Ewing
Keyword(s):  
Oxygen Uptake ◽  
Uptake Rate ◽  
Oxygen Transfer ◽  
Oxygen Uptake Rate ◽  
Transfer Efficiency ◽  
Theoretical Development ◽  
Process Conditions ◽  
Uptake Rates ◽  
Oxygen Transfer Efficiency ◽  
On Line

The off-gas technique for measuring oxygen transfer efficiency in aeration tanks under process conditions was proposed as an accurate technique for calibrating or verifying on-line methods used to estimate oxygen uptake rates. The theoretical development of the off-gas technique was presented. Application of this technique in verifying or calibrating existing on-line methods for estimating oxygen uptake rate was presented. Direct application as an on-line method for estimating oxygen uptake rate was also discussed.

Experience with Ceramic Plate Diffusers in Large Activated Sludge Plants

1992 ◽  
Vol 25 (4-5) ◽  
pp. 127-134
Author(s):  
R. Warriner ◽  
T. C. Rooney
Keyword(s):  
Activated Sludge ◽  
Oxygen Transfer ◽  
Cost Effective ◽  
Transfer Efficiency ◽  
Ceramic Plate ◽  
Flat Plates ◽  
Higher Power ◽  
Oxygen Transfer Efficiency ◽  
Basin Floor ◽  
The Difference

Fine pore aeration systems were evaluated in a U.S.EPA sponsored study of oxygen transfer efficiency in 26 activated sludge plants. Two plants in the study, those of the Milwaukee Metropolitan Sewerage District, had aeration systems composed of flat plates grouted into containers placed flush with the basin floor. The remaining plants in the study had aeration systems utilizing various disk, dome, and tube devices that are now in far more widespread use than the flat plates. The District's aeration basins gave better oxygen transfer efficiency than the other ceramic diffuser systems studied. The difference may have been the result of the high tank area to diffuser area ratio and the low air flux rates associated with the plate systems. At one MMSD plant there were also four basins with recently installed ceramic disk diffuser systems. This provided an opportunity for side-by-side comparisons between the disks and the flat plates in containers. An analysis of diffuser system first costs and energy costs indicated that the ceramic plate system could be cost effective at higher power costs, but not at the prices presently paid by the District for power.

Study of Air Bubble Formation for Wastewater Treatment

2011 ◽  
Author(s):  
Bryan A. Miletta ◽  
R. S. Amano ◽  
Ammar A. T. Alkhalidi ◽  
Jin Li
Keyword(s):  
Wastewater Treatment ◽  
Oxygen Transfer ◽  
Surface Membrane ◽  
Bubble Formation ◽  
High Oxygen ◽  
Transfer Efficiency ◽  
Intimate Contact ◽  
Rubber Membrane ◽  
Unit Process ◽  
Oxygen Transfer Efficiency

Aeration, a unit process in which air and water are brought into intimate contact, is an extremely important step in the process of wastewater treatment. The two most common systems of aeration are subsurface and mechanical. A mechanical system agitates the wastewater by various means (e.g. paddles, blades, or propellers) to introduce air from the atmosphere. Subsurface aeration is the release of air, in the form of bubbles, within the tank of wastewater to supply the microorganisms with the required amount of oxygen they need to metabolize and break down the organic material suspended in the wastewater. The bubbles of Air are released from the bottom of the wastewater tank through diffusers. These diffusers have a surface membrane, usually made of punched rubber, to create the fine bubbles with high oxygen transfer efficiency from supplied air to the diffusers. Since the energy crisis in the early 1970’s, there has been increased interest in these systems due to its high oxygen transfer efficiency. This paper covers experimentation of different air diffuser membranes, varying in material, used in the aeration process of wastewater treatment. Rubber, EPDM rubber (ethylene-propylene-diene Monomer) and PTFE Polytetrafluoroethylene membranes coated membranes were tested. Experimental results showed that the rubber membrane produced the smallest bubble size against expectation. This could be a result of the coating being on the top surface only and the bubble starts from inside the punch.

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