Aeration of water with oxygen microbubbles and its purging effect

2017 ◽  
Vol 825 ◽  
pp. 16-28 ◽  
Author(s):  
Tatsuya Yamashita ◽  
Keita Ando
Keyword(s):  
Dissolved Oxygen ◽  
Tap Water ◽  
Gas Bubbles ◽  
Circulation System ◽  
Dissolved Gases ◽  
Binary Diffusion ◽  
Nitrogen Gas ◽  
Dissolved Nitrogen ◽  
Supplemental Experiment ◽  
Glass Surfaces

In this paper, we apply aeration with oxygen microbubbles to tap water; the intent is to quantitatively evaluate whether nitrogen gas originally dissolved in the water under the atmosphere is purged by the aeration with oxygen microbubbles. Oxygen microbubbles are continuously injected into the circulation system of tap water open to the atmosphere. While the concentration of dissolved oxygen (DO) can be detected by a commercial DO meter, that of dissolved nitrogen (DN) is unavailable. To detect the DN level, we observe the growth of millimetre-sized gas bubbles nucleated at glass surfaces in contact with the aerated water and compare it with the multi-species theory of Epstein and Plesset where the (unknown) DN concentration is treated as a fitting parameter. In the theory, we solve binary diffusion of each gas species (oxygen or nitrogen) in the water independently, under the assumption that the dissolved gases are sufficiently dilute. Comparisons between the experiment and the theory suggest that the DN in the water is effectively purged by the oxygen aeration. The supplemental experiment of aeration with nitrogen microbubbles is also documented to show that the DO can be effectively purged as well.

Supersaturation of Nitrogen in Water During Passage Through Hydroelectric Turbines at Mactaquac Dam

1973 ◽  
Vol 30 (9) ◽  
pp. 1392-1394 ◽  
Author(s):  
J. Rod Macdonald ◽  
R. A. Hyatt
Keyword(s):  
Dissolved Oxygen ◽  
New Brunswick ◽  
Salmo Salar ◽  
Hydroelectric Station ◽  
Gas Bubbles ◽  
Anguilla Rostrata ◽  
Fish Kills ◽  
Nitrogen Gas ◽  
Dissolved Nitrogen ◽  
Generating System

Two fish kills occurred at the Saint John River, New Brunswick, below the Mactaquac Hydroelectric Station in the summer of 1968. Gas bubbles, commonly associated with nitrogen supersaturation, were observed on dead and dying salmon (Salmo salar) and eels (Anguilla rostrata). Tests showed that the concentrations of dissolved oxygen and nitrogen gases were substantially increased when water passed through the turbine generating system at low generating levels. Concentrations of dissolved nitrogen gas increased by as much as 20% above atmospheric equilibrium.

Degasification of mixed liquor improves settling and biological nutrient removal

2010 ◽  
Vol 5 (1) ◽  
Author(s):  
M. Maciejewski ◽  
J. A. Oleszkiewicz ◽  
A. Golcz ◽  
A. Nazar
Keyword(s):  
Nutrient Removal ◽  
Gas Bubbles ◽  
Biological Nutrient Removal ◽  
Surface Loading ◽  
Nitrogen Gas ◽  
Mixed Liquor ◽  
Loading Rates ◽  
Dissolved Nitrogen ◽  
Solids Separation ◽  
Sludge Settling

Degasification of mixed liquor by subjecting it to vacuum is a physical process used in biological nutrient removal (BNR) to improve settleability and allow for achieving higher mixed liquor suspended solids (MLSS). Vacuum degassing installation is located between the last cell of the bioreactor and secondary clarifiers. In this process two operations are performed: gas bubbles contained in mixed liquor leaving the bioreactor are removed and concentration of gasses (mainly nitrogen gas) dissolved in the liquid is reduced. Lack of gas bubbles and concentration of dissolved nitrogen gas below saturation in mixed liquor significantly improved sludge settling in secondary clarifiers and eliminated floating scum formation. Presented settleability tests of degasified MLSS and return activated sludge (RAS) from various BNR facilities showed continued settling and/or thickening for over 3 h at room temperature, without exhibiting any solids separation. Settleability tests of biomass that was not degasified typically led to flotation of portion of the sludge after about 1.5 h. Plants equipped with vacuum degasification consistently operate at larger than typically recommended final clarifier sludge surface loading rates. Rates as high as 180-220 kg TSS/m2d and deep sludge blankets have been employed. Such plants were shown to maintain operational levels of MLSS at 4500 to 6000 mg/L and higher.

scholarly journals Non-obvious Problems in Clark Electrode Application at Elevated Temperature and Ways of Their Elimination

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
M. V. Miniaev ◽  
M. B. Belyakova ◽  
N. V. Kostiuk ◽  
D. V. Leshchenko ◽  
T. A. Fedotova
Keyword(s):  
Gas Phase ◽  
Oxygen Sensor ◽  
Gas Bubbles ◽  
Oxygen Sensors ◽  
Measuring System ◽  
Dissolved Gases ◽  
Spontaneous Release ◽  
Complete Exclusion ◽  
Typical Temperature ◽  
Clark Electrode

Well-known cause of frequent failures of closed oxygen sensors is the appearance of gas bubbles in the electrolyte. The problem is traditionally associated with insufficient sealing of the sensor that is not always true. Study of a typical temperature regime of measurement system based on Clark sensor showed that spontaneous release of the gas phase is a natural effect caused by periodic warming of the sensor to a temperature of the test liquid. The warming of the sensor together with the incubation medium causes oversaturation of electrolyte by dissolved gases and the allocation of gas bubbles. The lower rate of sensor heating in comparison with the medium reduces but does not eliminate the manifestation of this effect. It is experimentally established, that with each cycle of heating of measuring system up to 37°C followed by cooling the volume of gas phase in the electrolyte (KCl; 60 g/L; 400 μL) increased by 0.6 μL approximately. Thus, during just several cycles it can dramatically degrade the characteristics of the sensor. A method was developed in which the oxygen sensor is heated in contact with the liquid, (depleted of dissolved gases), allowing complete exclusion of the above-mentioned effect.

RBS and PIXE Analysis of Alteration Layers on Waste Glass in a Leaching Test Under Reducing Condition

1993 ◽  
Vol 333 ◽  
Author(s):  
Kaoru Sasakawa ◽  
Tsuyoshi Imakita ◽  
Ryutaro Wada ◽  
Fumio Matsuda
Keyword(s):  
Carbon Steel ◽  
Corrosion Test ◽  
Waste Glass ◽  
Emission Spectrometry ◽  
Leaching Test ◽  
Nitrogen Gas ◽  
Pixe Analysis ◽  
X Ray ◽  
Glass Surfaces ◽  
Reducing Condition

ABSTRACTA corrosion test of model waste glass was carried out with and without a carbon steel under reducing condition in a glove box purged with nitrogen gas, and then the characteristics of alteration layers of the glass were examined.On the glass surfaces corroded under reducing condition with carbon steel, a thick precipitated layer was observed by Scanning Electron Microscopy (SEM). In this layer concentrated iron was observed by Particle Induced X-ray Emission Spectrometry (PIXE) and Rutherford Backseattering Spectrometry (RBS). Such a thick precipitated layer was not observed on the corroded glass under oxidizing conditions with and without carbon steel and reducing condition without carbon steel.

scholarly journals The effect of the size of particles on mineralization of Oxycaryum cubense (Poepp. & Kunth) Lye

2006 ◽  
Vol 66 (2b) ◽  
pp. 641-650 ◽  
Author(s):  
I. Bianchini Jr. ◽  
M. B. Cunha-Santino
Keyword(s):  
Dissolved Oxygen ◽  
Aquatic Macrophyte ◽  
Tap Water ◽  
Oxbow Lake ◽  
Order Kinetic ◽  
Dissolved Ions ◽  
Order Kinetic Model ◽  
Mineralization Processes ◽  
Size Of Particles ◽  
Fragmentation Processes

Assays were carried out to evaluate effects of detritus size on the mineralization of an aquatic macrophyte, the Oxycaryum cubense. Samples of plant and water were collected from an oxbow lake, the Infernão lagoon (21° 35' S and 47° 51' W) located at Mogi Guaçu river floodplain. The plants were taken to the laboratory, washed under tap water, dried (50 °C) and fractioned into six groups according to their size, viz. 100, 10, 1.13, 0.78, 0.61 and 0.25 mm. Decomposition chambers were prepared by adding 1.0 g of plant fragments to 4.1 L of water lagoon. In sequence, the incubations were aerated and the concentrations of dissolved oxygen, the pH, the electric conductivity and the temperature were monitored for 120 days. The occurrence of anaerobic processes was avoided by reoxygenating the solutions. The experimental results were fitted to a first order kinetic model and the consumption of dissolved oxygen from mineralization processes was obtained. The physical process of fragmentation of O. cubense detritus is unlikely to promote the consumption of higher quantities of dissolved oxygen in mineralization processes meaning that fragmentation should not interfere in the balance of DO in this aquatic system, however fragmentation processes favored the acidification and increased the liberation of dissolved ions from the Infernão lagoon.

scholarly journals Removal of Dissolved Oxygen in Sudachi Juice by Nitrogen Gas Pressurization

2005 ◽  
Vol 52 (4) ◽  
pp. 178-182 ◽  
Author(s):  
Yoshihisa Muramoto ◽  
Katsuhiro Tamura ◽  
Takanori Taniwaki ◽  
Shingo Takai ◽  
Yoshihisa Suzuki
Keyword(s):  
Dissolved Oxygen ◽  
Nitrogen Gas

scholarly journals Experimental researches on vegetable assimilation and respiration. VIII.―A new method for estimating the gaseous exchanges of submerged plants

1911 ◽  
Vol 83 (565) ◽  
pp. 374-388 ◽  
Keyword(s):  
Gas Bubbles ◽  
New Method ◽  
Dissolved Gases ◽  
Submerged Plants ◽  
Surrounding Water ◽  
Wide Range ◽  
Satisfactory Method ◽  
Experimental Researches ◽  
Very High

The method in universal use for evaluating assimilation in submerged plants consists in counting or measuring the evolution of bubbles of gas. This method gives satisfactory results in medium conditions, but fails at both extremes of the conditions—light, temperature, and CO 2 -supply—which chiefly control the magnitude of assimilation. Critical work over a wide range of conditions is therefore impossible with it. A really satisfactory method must take account of the- alteration of the dissolved gases as well as of those that are liberated as gas-bubbles; because, when assimilation is slight, the oxygen formed may all dissolve in the water and no bubbles appear. When temperature is high the bubbles consist partly of other gases physically liberated from the water, and when the CO 2 -content of the surrounding water is very high the bubbles escaping will consist chiefly of this gas.

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