PERFORMANCE EVALUATION OF LOCALLY FABRICATED MECHANICAL SURFACE AERATOR

Experimental analysis for a fabricated Low-Speed surface aerator that can be used in wastewater and water treatment is presented in this research. The designed impeller configuration was tested to determine its power consumption, standard oxygen transfer rate (SOTR), and standard aeration efficiency (SAE). Impeller oxygen transfer and power consumption in a scaled laboratory tank were measured during aeration phase. The impeller was consisting of 8 inclines flat blades with an angle of 45° from center of the disc, was operated at 3 different immersion depths and 5 different rotational speeds for examining the impact of such factors on impeller efficiency. The results recorded that the best standard aeration efficiency for this configuration is (0.206 Kg. O2/KW.hr) at 120rpm and 7cm depth of the submersion, i.e. submersion depth to impeller diameter (h/D) ratio equals 0.175. Submergence depth increase beyond this limit would result in SAE decrease and definitely result into more power consumption.

Download Full-text

Design of aeration systems in activated sludge plants at different wastewater temperatures

Water Practice & Technology ◽

10.2166/wpt.2012.010 ◽

2012 ◽

Vol 7 (1) ◽

Author(s):

T. Guenkel ◽

M. Wagner

Keyword(s):

Oxygen Uptake ◽

Activated Sludge ◽

Uptake Rate ◽

Oxygen Transfer ◽

Transfer Rate ◽

Oxygen Uptake Rate ◽

Oxygen Transfer Rate ◽

Decisive Factor ◽

Volume Increase ◽

The Impact

The standard oxygen transfer rate (SOTR) is the decisive factor in the dimensioning of activated sludge plants. It depends on the required oxygen uptake rate (OUR) by microorganisms. The dependencies of the SOTR and OUR on the wastewater temperature (range 5–30 °C) are discussed. It is shown that the absolute values of the SOTR depend only slightly on the wastewater temperature, while the specific values, in relation to the aerated tank volume, increase considerably as a function of the wastewater temperature. Within this context, the decisive dimensioning temperature is discussed. In addition, two design approaches for determining the SOTR, temperature-dependant and temperature-independent, are presented and compared, showing the impact of the water dependency. Finally, the sensitivity of the decisive factors for determining the SOTR is discussed, particularly addressing the influence of the α-value.

Download Full-text

Two-fluids RANS predictions of gas cavities, power consumption, mixing time and oxygen transfer rate in an aerated fermenter scale-down stirred with multiple impellers

Biochemical Engineering Journal ◽

10.1016/j.bej.2020.107867 ◽

2020 ◽

pp. 107867

Author(s):

Francesco Maluta ◽

Alessandro Paglianti ◽

Giuseppina Montante

Keyword(s):

Power Consumption ◽

Oxygen Transfer ◽

Transfer Rate ◽

Mixing Time ◽

Oxygen Transfer Rate ◽

Two Fluids ◽

Scale Down

Download Full-text

Evolution of the specific power consumption and oxygen transfer rate in alginate-producing cultures of Azotobacter vinelandii conducted in shake flasks

Biochemical Engineering Journal ◽

10.1016/j.bej.2007.02.019 ◽

2007 ◽

Vol 36 (2) ◽

pp. 73-80 ◽

Cited By ~ 36

Author(s):

Carlos Peña ◽

Cyril P. Peter ◽

Jochen Büchs ◽

Enrique Galindo

Keyword(s):

Power Consumption ◽

Oxygen Transfer ◽

Transfer Rate ◽

Azotobacter Vinelandii ◽

Oxygen Transfer Rate ◽

Specific Power ◽

Specific Power Consumption ◽

Shake Flasks

Download Full-text

DISTRIBUTION OF OXYGEN TRANSFER RATE IN STIRRED BIOREACTORS WITH SIMULATED BROTHS

Environmental Engineering and Management Journal ◽

10.30638/eemj.2008.034 ◽

2008 ◽

Vol 7 (3) ◽

pp. 199-211 ◽

Cited By ~ 1

Author(s):

Dan Cascaval ◽

Anca-Irina Galaction ◽

Stefanica Camarut ◽

Radu Z. Tudose

Keyword(s):

Oxygen Transfer ◽

Transfer Rate ◽

Oxygen Transfer Rate ◽

Stirred Bioreactors

Download Full-text

Estimation of oxygen transfer rate in sequencing batch reactor

Water Science & Technology ◽

10.2166/wst.1996.0458 ◽

1996 ◽

Vol 34 (3-4) ◽

pp. 413-420

Author(s):

Y. C. Liao ◽

D. J. Lee

Keyword(s):

Dissolved Oxygen ◽

Oxygen Transfer ◽

Transfer Rate ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Oxygen Transfer Rate ◽

Intermittent Aeration ◽

Transient Effects ◽

Operational Parameters ◽

Transient Model

Transient model of oxygen transfer rate in a sequencing batch reactor is derived and solved numerically. The dissolved oxygen response under several conditions is analyzed. Effects of operational parameters and liquid bath height are studied. When with short, intermittent aeration periods, the transient effects on oxygen transfer rate may be substantial and should be taken into considerations. An example considering bioreaction is also given.

Download Full-text

Two-Phase Flow Mass Transfer Analysis of Airlift Pump for Aquaculture Applications

Fluids ◽

10.3390/fluids6060226 ◽

2021 ◽

Vol 6 (6) ◽

pp. 226

Author(s):

Rashal Abed ◽

Mohamed M. Hussein ◽

Wael H. Ahmed ◽

Sherif Abdou

Keyword(s):

Mass Transfer ◽

Oxygen Transfer ◽

Transfer Rate ◽

Two Phase Flow ◽

Oxygen Transfer Rate ◽

Flow Patterns ◽

Oxygen Mass Transfer ◽

Phase Flow ◽

Two Phase ◽

Airlift Pump

Airlift pumps can be used in the aquaculture industry to provide aeration while concurrently moving water utilizing the dynamics of two-phase flow in the pump riser. The oxygen mass transfer that occurs from the injected compressed air to the water in the aquaculture systems can be experimentally investigated to determine the pump aeration capabilities. The objective of this study is to evaluate the effects of various airflow rates as well as the injection methods on the oxygen transfer rate within a dual injector airlift pump system. Experiments were conducted using an airlift pump connected to a vertical pump riser within a recirculating system. Both two-phase flow patterns and the void fraction measurements were used to evaluate the dissolved oxygen mass transfer mechanism through the airlift pump. A dissolved oxygen (DO) sensor was used to determine the DO levels within the airlift pumping system at different operating conditions required by the pump. Flow visualization imaging and particle image velocimetry (PIV) measurements were performed in order to better understand the effects of the two-phase flow patterns on the aeration performance. It was found that the radial injection method reached the saturation point faster at lower airflow rates, whereas the axial method performed better as the airflow rates were increased. The standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) were calculated and were found to strongly depend on the injection method as well as the two-phase flow patterns in the pump riser.

Download Full-text

Oxygen Supply Method Using Gas-Permeable Film for Wastewater Treatment

Water Science & Technology ◽

10.2166/wst.1993.0169 ◽

1993 ◽

Vol 28 (7) ◽

pp. 243-250 ◽

Cited By ~ 17

Author(s):

Y. Suzuki ◽

S. Miyahara ◽

K. Takeishi

Keyword(s):

Wastewater Treatment ◽

Energy Consumption ◽

Oxygen Transfer ◽

Transfer Rate ◽

Oxygen Supply ◽

Oxygen Transfer Rate ◽

High Energy ◽

High Rate ◽

N Removal ◽

High Energy Consumption

Gas-permeable film can separate air and water, and at the same time, let oxygen diffuse from the air to the water through the film. An oxygen supply method using this film was investigated for the purpose of reducing energy consumption for wastewater treatment. The oxygen transfer rate was measured for the cases with or without biofilm, which proved the high rate of oxygen transfer in the case with nitrifying biofilm which performed nitrification. When the Gas-permeable film with nitrifying biofilm was applied to the treatment of wastewater, denitrifying biofilm formed on the nitrifying biofilm, and simultaneous nitrification and denitrification occurred, resulting in the high rate of organic matter and T-N removal (7 gTOC/m2/d and 4 gT-N/m2/d, respectively). However, periodic sloughing of the denitrifying biofilm was needed to keep the oxygen transfer rate high. Energy consumption of the process using the film in the form of tubes was estimated to be less than 40% of that of the activated sludge process.

Download Full-text

Flow Mixing Enhancement from Balloon Pulsations in an Intravenous Oxygenator

Journal of Biomechanical Engineering ◽

10.1115/1.1894260 ◽

2004 ◽

Vol 127 (3) ◽

pp. 400-415 ◽

Cited By ~ 3

Author(s):

Amador M. Guzmán ◽

Rodrigo A. Escobar ◽

Cristina H. Amon

Keyword(s):

Numerical Simulations ◽

Oxygen Transfer ◽

Fiber Bundle ◽

Transfer Rate ◽

Oxygen Transfer Rate ◽

Three Dimensional ◽

Time Dependent ◽

Fiber Placement ◽

Flow Mixing ◽

Dependent Flow

Computational investigations of flow mixing and oxygen transfer characteristics in an intravenous membrane oxygenator (IMO) are performed by direct numerical simulations of the conservation of mass, momentum, and species equations. Three-dimensional computational models are developed to investigate flow-mixing and oxygen-transfer characteristics for stationary and pulsating balloons, using the spectral element method. For a stationary balloon, the effect of the fiber placement within the fiber bundle and the number of fiber rings is investigated. In a pulsating balloon, the flow mixing characteristics are determined and the oxygen transfer rate is evaluated. For a stationary balloon, numerical simulations show two well-defined flow patterns that depend on the region of the IMO device. Successive increases of the Reynolds number raise the longitudinal velocity without creating secondary flow. This characteristic is not affected by staggered or non-staggered fiber placement within the fiber bundle. For a pulsating balloon, the flow mixing is enhanced by generating a three-dimensional time-dependent flow characterized by oscillatory radial, pulsatile longitudinal, and both oscillatory and random tangential velocities. This three-dimensional flow increases the flow mixing due to an active time-dependent secondary flow, particularly around the fibers. Analytical models show the fiber bundle placement effect on the pressure gradient and flow pattern. The oxygen transport from the fiber surface to the mean flow is due to a dominant radial diffusion mechanism, for the stationary balloon. The oxygen transfer rate reaches an asymptotic behavior at relatively low Reynolds numbers. For a pulsating balloon, the time-dependent oxygen-concentration field resembles the oscillatory and wavy nature of the time-dependent flow. Sherwood number evaluations demonstrate that balloon pulsations enhance the oxygen transfer rate, even for smaller flow rates.

Download Full-text