Applying fine bubble aeration to small aeration tanks

2001 ◽  
Vol 44 (2-3) ◽  
pp. 203-210 ◽  
Author(s):  
Ph. Duchène; ◽  
E. Cotteux ◽  
S. Capela
Keyword(s):  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Open Channels ◽  
Aeration System ◽  
Fine Bubble ◽  
Aeration Efficiency ◽  
Practical Guidelines ◽  
High Investment ◽  
Cylindrical Tanks ◽  
Grid Layout

Because the aeration system in an activated sludge plant typically represents a large part of the total energy requirements, designers and operators need accurate oxygen transfer information to make the aeration system as energy efficient as possible. This paper presents clean water tests performed at 38 wastewater treatment plants. The Specific Aeration Efficiency results (SAE, kgO2/kWh) are reported for: (1) large open channels (volume higher than 1000 m3), (2) small open channels, (3) total floor coverage cylindrical tanks, and (4) cylindrical tanks with a grid arrangement. Some practical guidelines can be drawn, some of them being: (1) high SAE can be achieved at small aeration tanks (<1000m3), applying cylindrical tanks with a total floor coverage arrangement of diffusers, volumetric blowers, and moderate air flow rates per diffuser area; (2) the high investment cost of this configuration can be justified with respect to a grid layout characterized by spiral liquid circulation which affects the oxygen transfer; (3) small open channels can meet sufficient SAE values but fail to meet in this range of tank volumes those of total floor coverage cylindrical tanks.

Oxygen transfer and aeration efficiency - influence of diffuser submergence, diffuser density, and blower type

1998 ◽  
Vol 38 (3) ◽  
pp. 1-6 ◽  
Author(s):  
Martin R. Wagner ◽  
H. Johannes Pöpel
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Flow Rate ◽  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Air Flow ◽  
Oxygen Absorption ◽  
Air Flow Rate ◽  
Fine Bubble ◽  
Aeration Efficiency

The main factors of fine bubble aeration systems in uniform arrangement in clean water are the air flow rate, the depth of submergence of the diffusers, and the diffuser density. While the influence of the air flow rate on the oxygen transfer parameters is known, knowledge of the influence of the depth of submergence and the diffuser density on the specific oxygen transfer efficiency SOTE [%/m] and on the specific oxygen absorption SOA [g/m3·m at STP] is very limited. Both parameters are of great importance in dimensioning fine bubble aeration systems. Therefore, a literature review was conducted to show the influence of the diffuser submergence and density and the type of blower on oxygen transfer and aeration efficiency. The main review results are, that higher values of specific oxygen absorption can be obtained at higher diffuser density; secondly, the volumetric oxygen transfer rate VOTR [g/m3·h] is higher with increasing depth of submergence at the same air flow rate. Also it can be stated that with greater depth of submergence the specific oxygen absorption [g/m3·m at STP] is reduced. Dependent on the air flow rate and the pressure head, the energy consumption [Wh/m3·m at STP] of the blowers used in wastewater treatment plants is different. For example, the energy consumption varies from 4.3 [Wh/m3·m at STP] (positive displacement blower) to 3.0 [Wh/m3·m at STP] (turbo-compressors) at a pressure of 10 m and an air flow rate of 5,000 m3/h at STP. From the results of the literature review the following conclusions can be drawn: (1) High specific oxygen absorption values (SOA) [g/m3·m at STP] can be achieved applying shallow tanks, high diffuser densities and low specific air flow rates; (2) High aeration efficiencies (AE) [kg/kWh] can be obtained by applying high volumetric oxygen transfer rates and adequate selection of the blowers used at the wastewater treatment plants.

Non-Conventional Technologies for the Manufacturing Systems Use in Biological Wastewater Treatment Process

2015 ◽  
Vol 809-810 ◽  
pp. 1573-1578
Author(s):  
Casen Panaitescu ◽  
Monica Emanuela Stoica ◽  
Ciner Fehiman
Keyword(s):  
Wastewater Treatment ◽  
Oxygen Transfer ◽  
Manufacturing Systems ◽  
Wastewater Treatment Plants ◽  
Design Parameters ◽  
Biological Wastewater Treatment ◽  
Wastewater Treatment Process ◽  
Aeration System ◽  
Treatment Technologies ◽  
And Performance

Manufacture of wastewater treatment technologies is an important issue due to the complexity of design parameters and performance. Biological wastewater treatment is a process in which the intensity of oxygen transfer into water is an issue that has been extensively studied but yet insufficiently resolved. The present paper aims to describe an aeration system developed by the author in the laboratory by means of non-conventional technologies, and subsequently implemented in refinery wastewater treatment plants. The aeration system takes the form of modules, which are equipped with a new type of membrane. The analysis of the system performance revealed that oxygen transfer was 62%, specific adsorption of oxygen was 37 % and the specific oxygen transfer was 7%/m. The advantages of this new system are as follows: compared to existing technologies there is a higher rate of oxygen transfer into water; longer life; there are no dead zones in the basin as a result of their location; possibility of operating on separate sections.

scholarly journals Improving aeration systems in saline water (part II): effect of different salts and diffuser type on oxygen transfer of fine-bubble aeration systems

2021 ◽  
Author(s):  
J. Behnisch ◽  
M. Schwarz ◽  
J. Trippel ◽  
M. Engelhart ◽  
M. Wagner
Keyword(s):  
Oxygen Transfer ◽  
Large Scale ◽  
Saline Water ◽  
Tap Water ◽  
Pilot Scale ◽  
Mixed Salt ◽  
Water Oxygen ◽  
Aeration System ◽  
Fine Bubble ◽  
Scale Test

Abstract The objective of the present study is to investigate the different effects on the oxygen transfer of fine-bubble aeration systems in saline water. Compared to tap water, oxygen transfer increases due to the inhibition of bubble coalescence. In Part I of the present study, we investigated in lab-scale experiments the effect of design of diffuser membrane. The objective of Part II is the assessment of effects of different salts, diffuser type and diffuser density. We measured the concentration of various salts (MgCl2; CaCl2; Na2SO4; NaCl; KCl) above which coalescence is fully inhibited and oxygen transfer reaches its maximum (referred to as the critical coalescence concentration; CCC). For this purpose, we developed a new analytical approach, which enables to investigate the coalescence behaviour of any aeration system and (mixed) salt solution quickly and easily by evaluating the results of oxygen transfer tests. To investigate the transferability to large scale and the effect of diffuser type and density, we repeated lab-scale experiments in a 17,100 L pilot scale test tank and carried out additional tests with tube and plate diffusers at different diffuser densities. The results show, that despite the higher pressure drop, diffusers with dense slit density and smaller slits are to be recommended in order to improve efficiency of aeration systems in saline water.

scholarly journals Reverse flexing as a physical/mechanical treatment to mitigate fouling of fine bubble diffusers

2017 ◽  
Vol 76 (7) ◽  
pp. 1595-1602
Author(s):  
Victory O. Odize ◽  
John Novak ◽  
Haydee De Clippeleir ◽  
Ahmed Al-Omari ◽  
Joshua D. Smeraldi ◽  
...  
Keyword(s):  
Wastewater Treatment Plants ◽  
Energy Requirement ◽  
System Optimization ◽  
High Energy ◽  
High Rate ◽  
Washington Dc ◽  
System A ◽  
Aeration System ◽  
Fine Bubble ◽  
Bubble Diffusers

Achieving energy neutrality has shifted focus towards aeration system optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. A study on fine bubble diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha was carried out in Blue Plains, Washington, DC. Four polyurethane fine bubble diffusers were installed in a pilot reactor column fed with high rate activated sludge from a full scale system. A mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2), while two diffusers were kept as a control (i.e., no reverse flexing). There was a 45% increase in DWP of the control diffuser after 17 months of operation, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show significant increase in DWP, and in comparison to the control diffuser prevented about 35% increase in DWP. Hence, reverse flexing potentially saves blower energy, by reducing the pressure burden on the air blower which increases blower energy requirement. However, no significant impact of the RF treatment in preventing a decrease in alpha-fouling (αF) of the fine pore diffusers, over time in operation was observed.

Aeration of large-scale municipal wastewater treatment plants: state of the art

2008 ◽  
Vol 57 (7) ◽  
pp. 973-978 ◽  
Author(s):  
Diego Rosso ◽  
Lory E. Larson ◽  
Michael K. Stenstrom
Keyword(s):  
Wastewater Treatment ◽  
Beneficial Effect ◽  
Oxygen Transfer ◽  
Large Scale ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Biomass Concentration ◽  
Municipal Wastewater Treatment ◽  
Unit Energy ◽  
Aeration Efficiency

Aeration is the most energy-intensive operation in wastewater treatment, amounting to 45–75% of plant energy costs. Fine-pore diffusers are today almost ubiquitous in municipal wastewater aeration, due to their advantageous aeration efficiency (mass of oxygen transferred per unit energy required). Nevertheless, older municipal treatment facilities and many industrial treatment plants are still equipped with coarse-bubble or surface aerators. Fine-pore diffusers are subject to two major disadvantages: a) fouling, if not cleaned periodically; b) decrease in oxygen transfer efficiency caused by dissolved surfactants. Coarse-bubble and surface aerators are typically not subject to the traditional problems affecting fine-pore diffusers. Nonetheless, they achieve oxygen transfer at the expense of increased energy intensity. The increased biomass concentration associated with high mean cell retention time (MCRT) operations has a beneficial effect on aeration. Nutrient-removing selectors are able to further increase aeration efficiency, as they sorb and utilize the readily available substrate which otherwise would accumulate at bubble surfaces and dramatically decrease aeration efficiency. We summarise here our 30-year long experience in aeration research, and results obtained with clean- and process-water tests are used to show the beneficial effects of high MCRT operations, the beneficial effect of selectors, and the decline of aeration efficiency due to dissolved surfactants.

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.

scholarly journals Performance of Closed Loop Venturi Aspirated Aeration System: Experimental Study and Numerical Analysis with Discrete Bubble Model

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1637
Author(s):  
Roohany Mahmud ◽  
Mustafa Erguvan ◽  
David W. MacPhee
Keyword(s):  
Experimental Study ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Oxygen Transfer Rate ◽  
Ideal Gas ◽  
Bulk Fluid ◽  
Aeration System ◽  
Aeration Efficiency ◽  
Low Efficiency ◽  
Aeration Process

In wastewater treatment plants, aeration plays a significant role as it encourages aerobic respiration of microbes, which are necessary to break down carbonaceous matter in the waste stream. This process can account for the majority of energy use in wastewater treatment plants. The aeration process is also necessary in odor control in lagoons and in the aquaculture industry. Generally, the aeration process is accomplished with compressors or blowers which can be of low efficiency due to ideal gas laws. This study introduces the idea of increasing aeration efficiency by looping water from a reservoir through a piping network which includes a venturi aspirator at its inlet. For this purpose, an experimental study has been conducted in a laboratory setup with a pump which pulls water from a tank, passes it through a Venturi aspirator and a helical piping network intended to increase bubble residence time, before depositing it back into the bulk fluid tank. This same process is modeled computationally, using a discrete bubble method (DBM), with good agreement with experiments. The overall purpose here is to determine the optimal configurations for standard aeration efficiency (SAE) and the standard oxygen transfer rate (SOTR). A parametric study has been implemented using the DBM based on different hydraulic and flow parameters. The model is also used to predict the SAE of a hypothetical aeration system. Results indicate that it is possible to achieve SAE values in the range of surface aerators or submersed jet aerators using the proposed aeration system with less complex components, thereby decreasing overall costs.

scholarly journals THE INFLUENCE OF AERATOR MOUNTING AND WASTEWATER TREATMENT PLANT DESIGN ON THE PERFORMANCE OF AERATION SYSTEMS

2010 ◽  
Vol 2 (5) ◽  
pp. 97-102
Author(s):  
Ala Sokolova ◽  
Mindaugas Rimeika
Keyword(s):  
Wastewater Treatment ◽  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Oxygen Transfer Rate ◽  
Treatment Plant ◽  
Aeration Tank ◽  
Plant Design ◽  
Operational Parameters ◽  
Aeration System ◽  
The Impact

The paper analyzes the impact of the way of mounting a tube diffuser, the design of an aeration tank and the presence of a fixed carrier on the operational parameters of aeration systems used in small wastewater treatment plants. It was found out that the vertically mounted tube diffuser decreased standard oxygen transfer rate (SOTR) of the aeration system by approximately 20% and standard oxygen transfer efficiency (SOTE) by 25% comparing to the horizontally mounted tube diffuser. It was also defined that the design of the aeration tank might have an impact on the operation parameters of the aeration system: when the centre shell used to protect a diffuser was dismantled from a test tank, SOTR and SOTE increased by approximately 20%. It was also established that the presence of the fixed carrier in the aeration tank did not have an impact on the performance of aeration systems. Finally, research was carried out to compare the operational parameters of two diffusers of different types offered on the market and used in small wastewater treatment plants. It was found out that the performance different type diffusers might vary considerably.

scholarly journals The Changing and Distribution Laws of Oxygen Transfer Efficiency in the Full-Scale IFAS Process

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1933
Author(s):  
Xuyang Liu ◽  
Xuejun Bi ◽  
Qing Huang ◽  
Xiaodong Wang ◽  
Ruihuan Gu ◽  
...  
Keyword(s):  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Plug Flow ◽  
Full Scale ◽  
Transfer Efficiency ◽  
Factors Affecting ◽  
Fine Bubble ◽  
Oxygen Transfer Efficiency ◽  
Distribution Laws ◽  
Two Sides

The integrated fixed-film activated sludge (IFAS) process has been widely used in the upgrading of wastewater treatment plants (WWTPs). The oxygen transfer efficiency (αOTE) is of great significance to the design and operation of the IFAS process. The carrier filling ratio (CFR) and aeration type are two critical factors affecting αOTE and standard oxygen transfer efficiency (αSOTE). However, the distribution and changing laws of αOTE and αSOTE in the full-scale IFAS process areunclear. To optimize the operation of a WWTP and to improve the αOTE of the aeration systems, several off-gas tests were conducted under different aeration types and different CFRs. The results show that for the aerobic tank investigated (the ratio of length and width was 8:1), the αOTE and the αSOTE of the middle of the aeration systems were higher than those of the other two sides. However, the reason for the low αOTE at the beginning and the end of the tank may be different. Coarse-bubble aeration systems had a lower αOTE and almost the same oxygenation capacity (αSOTE) as the fine-bubble aeration systems under constant CFR (43%). The average αSOTE (18.7–28.9%) of the hybrid aeration systems increased with increasing CFR (7.7–57.7%), and different locations exhibited different degrees of change. The results reveal the distribution and changing law of the αOTE of aeration systems in the IFAS process, and attention should be paid to the improvement of the OTE of the plug-flow IFAS process.

Sign in / Sign up

Export Citation Format

Share Document