scholarly journals EFFECT OF AIRFLOW RATE AND SUBMERGENCE OF DIFFUSERS ON OXYGEN TRANSFER CAPACITY OF DIFFUSED AERATION SYSTEMS

2006 ◽  
Vol 14 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Dr. Kossay K. Al-Ahmady
Keyword(s):  
Oxygen Transfer ◽  
Airflow Rate ◽  
Oxygen Transfer Capacity

scholarly journals The Influence of Optic and Polarographic Dissolved Oxygen Sensors Estimating the Volumetric Oxygen Mass Transfer Coefficient (KLa)

2016 ◽  
Vol 10 (8) ◽  
pp. 142 ◽  
Author(s):  
Gustavo Andrés Baquero-Rodríguez ◽  
Jaime A. Lara-Borrero
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Dissolved Oxygen ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Transfer ◽  
Airflow Rate ◽  
Oxygen Probe ◽  
Aeration System ◽  
Oxygen Measurement

Aeration is usually the most energy intensive part of the wastewater treatment process. Optimizing the aeration system is essential for reducing energy costs. Field tests oriented to estimate parameters related to oxygen transfer are a common approach to compare aeration systems. The aim of this research is to assess the effect of dissolved oxygen probe lag on oxygen transfer parameter estimation. Experimental procedures regarding to process automation and control were applied to quantify dissolved oxygen probe lag. We have measured oxygen transfer in clean water, under a wide range of conditions (airflow rate, diffuser characteristics and diffuser density), with optic and polarographic sensors for dissolved oxygen measurement. The oxygen transfer was measured as per ASCE Standard procedures. Nonparametric statistical tests were used to compare the estimated volumetric mass transfer coefficient KLa with different sensors. According to the results, there is not significant influence of the probe lag (also known as time constant) or probe characteristics on the parameters used to assess oxygen transfer efficiency. This fact has great relevance in common practice of aerobic process for wastewater treatment because dissolved oxygen monitoring is used as an input for decision making related to the energy optimization in the aeration system. Findings from these tests contradict previous studies which claim that lag time in polarographic sensors for the dissolved oxygen measurement can bias estimate KLa.

Study of a Non-Conventional Aeration System

1987 ◽  
Vol 19 (5-6) ◽  
pp. 869-876
Author(s):  
L. Raschid-Sally ◽  
M. Roustan ◽  
H. Roques ◽  
G. M. Faup
Keyword(s):  
Oxygen Transfer ◽  
Peclet Number ◽  
Péclet Number ◽  
Theoretical Approaches ◽  
Aeration System ◽  
Circulation Velocity ◽  
The Mean ◽  
Oxygen Transfer Capacity ◽  
Mean Circulation ◽  
Conventional Systems

A non-conventional aeration system for oxidation ditches using jets has been developed. The principle of this system is based on the separation of the 2 actions: aeration and circulation. It was concluded that the flow of the liquid in the channel can be successfully modelled using various theoretical approaches. The mean circulation velocity VC, the power dissipated P, and the Peclet number Pe are the 3 important parameters governing the circulation. The oxygen transfer capacity of the system has been studied and compares favourably with that of conventional systems. The advantage of such systems over conventional ones has been discussed.

Mass Transfer of Oxygen in Diffused Aeration Systems

1974 ◽  
Vol 1 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Donald S. Mavinic ◽  
Jatinder K. Bewtra
Keyword(s):  
Mass Transfer ◽  
Oxygen Transfer ◽  
Contact Time ◽  
Transfer Rate ◽  
Oxygen Transfer Rate ◽  
Laboratory Data ◽  
Operating Conditions ◽  
Airflow Rate ◽  
Transfer Coefficients ◽  
Water Characteristics

Starting from the fundamental concepts of mass transfer of gases into liquid, a comprehensive mathematical equation, relating the mass oxygen-transfer rate to the various parameters in diffused aeration systems, is developed.The important variables involved are the liquid film coefficient, temperature, waste water characteristics, bubble size, diffuser submergence, airflow rate, and the contact time. The contact time between the air bubbles and the oxygen absorbing liquid can be varied by changing the operating conditions of the aeration system in terms of the direction of air and liquid movement. Investigations on four such combinations are presented.The influence of the above-mentioned variables, individually or in combination, on the mass oxygen-transfer rate and overall oxygen transfer coefficient are discussed. The presentation is supported with laboratory data collected from aeration studies over a period of 3 years. With proper understanding of the influence of operating parameters on mass transfer coefficients, it should be possible to modify the design and operation of aeration basins in order to obtain increased oxygen transfer.

scholarly journals Oxygen Transfer Capacity as a Measure of Water Aeration by Floating Reed Plants: Initial Laboratory Studies

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1270
Author(s):  
Antonio Albuquerque ◽  
Peter Randerson ◽  
Andrzej Białowiec
Keyword(s):  
Oxygen Transfer ◽  
Laboratory Experiments ◽  
Aquatic Plant ◽  
Dry Mass ◽  
Ammonia Nitrogen ◽  
Subsurface Environment ◽  
Floating Vegetation ◽  
Reed Plants ◽  
The Individual ◽  
Oxygen Transfer Capacity

Reed-Phragmites australis (Cav.) Trin. ex Steud, an aquatic plant, commonly used in constructed wetlands for wastewater treatment, supplies oxygen into the subsurface environment. Reed may be used as a ‘green machine’ in the form of a floating vegetation cover with many applications: wastewater lagoons, manure lagoons or sewage sludge lagoons. An important measure of the performance of the plant system is the oxygen transfer capacity (OTC). Accurate prediction of the OTC in relation to reed biomass would be crucial in modelling its influence on organic matter degradation and ammonia–nitrogen oxygenation in such lagoons. Laboratory experiments aiming to determine OTC and its dependence on reed biomass were carried out. Eight plants with a total dry mass ranging from approximately 3 to 7 g were tested. Mean OTC was determined per plant: 0.18 ± 0.21 (g O2·m−3·h−1·plant−1), with respect to leaves-and-stem dry mass (dlsm): 44.91 ± 35.21 (g O2·m−3·h−1·g dlsm−1), and to total dry mass (dtm): 33.25 ± 27.97 (g O2·m−3·h−1·g dtm−1). In relation to the relatively small root dry mass (drm), the OTC value was 136.02 ± 147.19 (g O2·m−3·h−1·g drm−1). Measured OTC values varied widely between the individual plants (variation coefficient 115%), in accordance with their differing size. Oxygenation performance was greatest in the reed plants with larger above ground dry mass (>4 g dlsm), but no influence of the root dry mass on the OTC rate was found.

Analysis of Oxygen Transfer and Dissolved Oxygen Concentration Measurement Tests in a Wastewater Treatment Plant

2014 ◽  
Vol 656 ◽  
pp. 486-494
Author(s):  
Marius Daniel Roman ◽  
Raluca Andreea Felseghi
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Oxygen Transfer ◽  
Treatment Plant ◽  
Dissolved Oxygen Concentration ◽  
Coverage Area ◽  
Type Size ◽  
Oxygen Efficiency ◽  
Oxygen Transfer Capacity ◽  
Tank Geometry

The efficiency of oxygen transfer depends on many factors including the type, size and shape of diffusers and the tank geometry. In this paper, the effect of the depth of water in the tank and the extension of coverage area of diffusers on each of oxygen transfer capacity, efficiency and dissolved oxygen concentration is tested. Experimental procedure is adopted to evaluate the effect of dissolved oxygen concentration. The results of the case study showed that, both the depth of water and the extent of coverage area of diffuser had a significant effect on the tested parameters. The values of oxygen transfer capacity was 76,7 kg O2/h and oxygen efficiency (without agitation): 5,3 kg O2/h, oxygen efficiency (with agitation): 4,2 kg O2/h.

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