An Investigation of Effect of Stepped Chutes with End Sill on Aeration Performance

2003 ◽  
Vol 38 (3) ◽  
pp. 527-539 ◽  
Author(s):  
M. Emin Emiroglu ◽  
Ahmet Baylar
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Aquatic Plant ◽  
Hydraulic Structures ◽  
Oxygen Level ◽  
Oxygen Transfer Efficiency ◽  
Aeration Efficiency ◽  
Stepped Chute ◽  
Aeration Performance ◽  
Small Bubbles

Abstract Dissolved oxygen is essential to healthy streams and lakes. The dissolved oxygen level is an indication of how polluted the water is and how well the water can support aquatic plant and animal life. A higher dissolved oxygen level indicates better water quality. There is a significant oxygen transfer associated with most hydraulic structures because the air entrained into the flow is split into small bubbles, which greatly increases the surface area for transfer. Stepped chutes are a particular instance of this, and the aeration efficiency of such structures has not been studied in the laboratory and field. In this paper, the aeration performance of the stepped chutes with and without end sill was investigated in a large laboratory stepped chute. An empirical correlation predicting the oxygen transfer efficiency was developed for stepped chutes. The results indicated that l/h and s/h had a significant effect on the aeration efficiency of stepped chutes.

Aeration Performance of Triangular Notch Weirs at Recirculating System

2001 ◽  
Vol 36 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Ahmet Baylar ◽  
Tamer Bagatur ◽  
Ahmet Tuna
Keyword(s):  
Dissolved Oxygen ◽  
Aquatic Organisms ◽  
The Other ◽  
Hydraulic Structures ◽  
Air Bubbles ◽  
Adequate Supply ◽  
Oxygen Levels ◽  
Aeration Efficiency ◽  
Aeration Performance ◽  
Better Than

Abstract An adequate supply of dissolved oxygen is essential for the survival of aquatic organisms. Hydraulic structures can increase dissolved oxygen levels by creating turbulent conditions, where small air bubbles are carried into the bulk of the flow. Plunging overfall jets from weirs at recirculating systems are a particular instance of this. This paper seeks triangular notch weirs having different weir angle (α) and how they affect the aeration performance. It is demonstrated that the aeration efficiency of a 90° triangular notch weir is generally better than that of the other weirs.

scholarly journals Modelling and Simulation of Flexible Beam as Aerator to Generate Dissolved Oxygen in Water

2015 ◽  
Vol 773-774 ◽  
pp. 188-193
Author(s):  
Badrul Aisham Md Zain ◽  
Muhammad Amir Mat Shah ◽  
Ong Pauline ◽  
Noormaziah bte Jafferi
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Modelling And Simulation ◽  
Transfer Efficiency ◽  
Flexible Beam ◽  
Oxygen Level ◽  
Oxygen Transfer Efficiency ◽  
Beam Motion

This paper presents the simulation of the flexible aerator model as a new concept to generate dissolved oxygen. This method is implementing the flexible beam motion as a medium to circulate water and create wave. This paper is using the simulation to optimize the suitable parameters namely the length of flexible beam and the percentage of immerse in water. The best result of dissolved oxygen level were found during run the flexible beam aerator at 12 V with 0.65m length of flexible beam and immerses 25% in water. The flexible beam was successfully implemented as a new aerator concept where it is able to generate oxygen up to 8.6mg/L with the average Standard Oxygen Transfer Efficiency 1.84 kgO2/kWhr

An experimental study of nozzle diameters, aeration depths and angles on standard aeration efficiency (SAE) in a venturi aerator

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
M.R. Ghomi ◽  
M. Sohrabnejad ◽  
M. R. Ovissipour
Keyword(s):  
Experimental Study ◽  
Oxygen Transfer ◽  
Air Entrainment ◽  
Nozzle Diameter ◽  
Venturi Tube ◽  
Water Pump ◽  
Significant Difference ◽  
Oxygen Transfer Efficiency ◽  
Aeration Efficiency ◽  
Nozzle Size

A 1.1 kW submersible water pump with a venturi air injector was used in this study to examine the effects of three factors including nozzle diameter (14, 17 and 20 mm), aeration depth (20, 40 and 60 cm), and aeration angle (0, 22.5 and 45°) on standard aeration efficiency (SAE). For maximum air entrainment, HT / DT ratio and DT / DN ratio were equal to zero and 2, respectively. Among the first factor experiments, 14 mm nozzle diameter showed the highest SAE value (P<0.05). Although, 60 cm aeration depth and 45° aeration angle had more SAE value among other depths and angles, but there was not a significant difference (P>0.05) in each aeration depths and angles. Only, the determination coefficient for effect of nozzle diameters on SAE value showed a good result (R2= 0.958). The greatest oxygen transfer efficiency in this study has been achieved with using 14 mm nozzle size, 60 cm depth of aeration, and 45° angle of venturi tube in water aeration that was 1.166 kgO2/ kWh. Venturi aerators are very inexpensive in comparison with other aerators and have some other advantages that can be considered as one of the best devices for water aeration.

scholarly journals PERFORMANCE ANALYSIS OF 4-OUTLETS SPRAY AERATOR FOR PROCESSING OF INDIGOFERA LEAVES (Indigofera Tinctoria Linn) BECOMES NATURAL DYE SUBSTANCES

2017 ◽  
Vol 6 (2) ◽  
pp. 76-86
Author(s):  
Ida Bagus Putu Sukadana ◽  
I Made Rajendra ◽  
Ida Ayu Anom Arsani ◽  
I Wayan Suastawa
Keyword(s):  
Oxygen Transfer ◽  
Oxygen Transfer Rate ◽  
Natural Dye ◽  
Operational Characteristic ◽  
Air Velocity ◽  
Bottom Part ◽  
Oxygen Transfer Efficiency ◽  
Aeration Efficiency ◽  
Fermentation Solution ◽  
Sufficient Space

The commonly known natural dye substance processing for traditional clothes, such as batik and tenun (woven cloth) is fermentation. The fermentation process can specifically be continued with extraction to produce indigo paste. The process can be done mechanically, i.e. by stirring process, and chemically. In order to accelerate the production, manual process of aeration can be substituted with jet-spray aerator. The aerator prototype which has been developed is acrylic aerator tube with diameter of 240 mm and thickness of 5 mm. The tube was made 1 m long to provide with a sufficient space for indigo foam. Its bottom part is completed with spiral air hose having five small holes of 0.2, 0.4, and 0.6 mm diameter uniformly located along the height of solution in the tube. The aerator was designed for the 10 litters of fermentation solution of 1 kilogram indigofera leaves. Based on the mass of indigo paste produced, the optimum working condition of the aerator is achieved on 3.8 m/sec air velocity and supply pressure of 2 bar with duration of 60 minutes. The aeration test indicated operational characteristic was quite good, i.e. Oxygen Transfer Rate (OTR) of 3.6 kg/hour, Aeration Efficiency (AE) of 4.8 kg/kWh and factual Oxygen Transfer Efficiency (OTE) of 44%.

Aeration performance of hydrodynamic flow regulators

2013 ◽  
Vol 67 (12) ◽  
pp. 2692-2698 ◽  
Author(s):  
P. Wójtowicz ◽  
M. Szlachta
Keyword(s):  
Oxygen Transfer ◽  
Oxygen Transfer Rate ◽  
Pilot Scale ◽  
Hydrodynamic Flow ◽  
Oxygen Absorption ◽  
Discharge Mode ◽  
Wide Range ◽  
Aeration Efficiency ◽  
Aeration Performance ◽  
Aeration Capacity

Hydrodynamic flow regulators are used in environmental engineering as a replacement for traditional flow throttling devices. They are extremely efficient, reliable and free from the common disadvantages of traditional devices. Recent research by the authors indicated that the atomization of a liquid by hydrodynamic flow regulators accelerates oxygenation and may be used for improving the quality of wastewater and stormwater. To date, an evaluation of the aeration capacity of a hydrodynamic flow regulator at the pilot scale or in a practical situation has not been presented in the literature. This study presents the experimental results of oxygen absorption tests for conventional and modified cylindrical hydrodynamic flow regulators (patent pending). These devices were tested in a closed-circuit experimental setup at the semi-commercial scale. The aeration efficiency of hydrodynamic flow regulators was assessed by means of the overall standard oxygen transfer coefficient (KLa(20), h−1) and standard oxygen transfer rate (SOTR, gO2/h) for a wide range of tested configurations. The effect of flow rate and discharge mode on the aeration capacity of flow regulators was investigated. The values of KLa(20) for cylindrical hydrodynamic flow regulators obtained in the experiments were between 2.62 and 15.57 h−1 while SOTR values ranged from 53 to 316 gO2/h. The modified discharge mode with two active outlets allowed for an increase in aeration efficiency of up to 15% compared to conventional designs.

Detailed off-gas measurements for improved modelling of the aeration performance at the WWTP of Eindhoven

2016 ◽  
Vol 74 (1) ◽  
pp. 203-211 ◽  
Author(s):  
Y. Amerlinck ◽  
G. Bellandi ◽  
A. Amaral ◽  
S. Weijers ◽  
I. Nopens
Keyword(s):  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Saturation Index ◽  
Spatial And Temporal Variability ◽  
System A ◽  
Rate Limiting Step ◽  
Aeration System ◽  
Oxygen Transfer Efficiency ◽  
Gas Measurements ◽  
Aeration Performance

At wastewater treatment plants (WWTPs), the aerobic conversion processes in the bioreactor are driven by the presence of dissolved oxygen (DO). Within these conversion processes, the oxygen transfer is a rate limiting step as well as being the largest energy consumer. Despite this high importance, WWTP models often lack detail on the aeration part. An extensive measurement campaign with off-gas tests was performed at the WWTP of Eindhoven to provide more information on the performance and behaviour of the aeration system. A high spatial and temporal variability in the oxygen transfer efficiency was observed. Applying this gathered system knowledge in the aeration model resulted in an improved prediction of the DO concentrations. Moreover, an important consequence of this was that ammonium predictions could be improved by resetting the ammonium half-saturation index for autotrophs to its default value. This again proves the importance of balancing sub-models with respect to the need for model calibration as well as model predictive power.

PREDICTION OF DISSOLVED OXYGEN ON STEPPED SPILLWAY WITH DIFFERENT CONFIGURATION

2017 ◽  
Vol 79 (4) ◽  
Author(s):  
Very Dermawan ◽  
Djoko Legono ◽  
Denik Sri Krisnayanti
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Froude Number ◽  
Oxygen Transfer ◽  
Air Entrainment ◽  
Stepped Spillway ◽  
Oxygen Level ◽  
Stepped Spillways ◽  
Turbulence Flow ◽  
Bed Slope

The increase of water quality is related to the presence of dissolved oxygen. Even, the oxygen concentration in surface waters is a main indicator of the water quality for human use as well as for the aquatic biota. Air entrainment on stepped spillway is also recognised for its contribution to the oxygen transfer. The oxygen transfer on stepped spillways in skimming flow regime is increased due to earlier self-aeration and slower flow velocities in comparison to smooth spillways. This paper presents the results gained on a physical model by using a variety of different configurations of stepped spillway. The slopes of stepped spillway (θ) used are 30˚ and 45˚, the number of step (N) are 40 and 20, and two types of steps are flat steps and pooled steps. The experiments were conducted for ten Froude number (Fr) run ranging from 1.117 to 9.909. This research aimed to investigate the influence of different configuration in stepped spillway for predicting of dissolved oxygen. The results showed that the dissolved oxygen of the stepped spillway increases with an increase in chute of slope, number of step, and surface roughness on steps. The increases of Froude number as a function of discharge will cause turbulence flow becomes decreases, and the concentration of air bubble in the water will be decreased. The decreased value of turbulence flow will make dissolved oxygen level decrease. In skimming flow condition, the dissolved oxygen level decreases with increasing discharge per unit width especially for steep bed slope. 

scholarly journals AERATION AT OVERFLOW DAMS WITH CURVED SURFACES BY DIFFERENT FLASHBOARD SPILLWAYS

2014 ◽  
Vol 22 (3) ◽  
pp. 226-236 ◽  
Author(s):  
Kejian Chu ◽  
Zulin Hua ◽  
Lijun Ji
Keyword(s):  
Discharge Rate ◽  
Dimensionless Number ◽  
Curved Surfaces ◽  
Empirical Formulas ◽  
Oxygen Transfer Efficiency ◽  
Hydraulic Conditions ◽  
Aeration Efficiency ◽  
Different Types ◽  
Laboratory Investigations ◽  
Aeration Performance

Aeration using overflow dams is an eco-friendly and economical method of improving dissolved oxygen levels in polluted urban streams. Laboratory investigations of aeration performance in smooth spillways, as well as in parallel flashboard and interlaced flashboard spillways with different flashboard intervals, for overflow dams with curved surfaces have been conducted separately. Aeration efficiencies of the different types of spillways, in particular the effects of varying discharge rate, total spillway height, and flashboard interval, have been discussed in detail. The test data illustrate that aeration efficiency in all spillways increases with spillway height and decreases with increasing discharge. Flashboard spillways appear to provide significantly higher aeration efficiency than smooth ones, and aeration efficiency increases with the number of flashboards, but with a continuously declining growth rate. By combining Fds with hd*, a new dimensionless parameter Ψ is created to characterize the comprehensive effects of hydraulic conditions on aeration. Empirical formulas for oxygen-transfer efficiency in smooth, parallel flashboard, and interlaced flashboard spillways have been developed with Ψ and the dimensionless number of flashboards per unit area of spillway N* as independent variables, and the properties of these formulas are discussed.

Oxygen Transfer Measurements and Air Distribution for an Aeration Basin with Fine Bubble Diffusers

1988 ◽  
Vol 20 (4-5) ◽  
pp. 77-84
Author(s):  
Read Warriner
Keyword(s):  
Dissolved Oxygen ◽  
Uniform Distribution ◽  
Oxygen Transfer ◽  
Transfer Efficiency ◽  
Air Distribution ◽  
Dissolved Oxygen Concentration ◽  
Air Supply ◽  
Fine Bubble ◽  
Oxygen Transfer Efficiency ◽  
Longitudinal Pattern

The off-gas method was used to study oxygen transfer efficiency in a long, narrow activated sludge basin. The basin was equipped with square, ceramic, fine pore diffuser plates arranged in a uniform longitudinal pattern at a depth of 4.3 m. Oxygen transfer efficiency, at 20°C and zero dissolved oxygen concentration, during the second and third years following diffuser cleaning, was between 15 and 17%. A uniform distribution of air to the tank was compared with a tapered air supply (more air at the inlet end and less at the outlet). The tapered air supply gave lower dissolved oxygen at the outlet and did not increase overall oxygen transfer. With a 3 to 5-fold variation in air flow, at either the inlet or outlet zone of the basin, the oxygen transfer efficiency, adjusted for zero dissolved oxygen, stayed constant.

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