Journal articles: 'Surface Aerators'

1

Deshmukh, N. A., and J. B. Joshi. "Surface Aerators." Chemical Engineering Research and Design 84, no. 11 (November 2006): 977–92. http://dx.doi.org/10.1205/cherd05066.

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2

Janssen, P. M. J., K. Meinema-Linders, and R. P. Niermans. "Surface aeration and a small footprint can be combined." Water Science and Technology 46, no. 4-5 (August 1, 2002): 309–16. http://dx.doi.org/10.2166/wst.2002.0613.

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In densely populated areas new WWTPs will need to be designed on a relatively small area. This paper describes a deep Carrousel© (oxidation ditch) concept resulting in a “small footprint” for the aeration basin combined with an efficient and flexible oxygen input. To enable surface aeration in a deep Carrousel system, the basin was provided with so-called draft tubes, vertical cylinders located underneath aerators, almost extending down to the bottom. A draft tube enables the aerator to draw sludge/water mixture from the bottom of the tank, thereby ensuring proper oxygenation of the tank contents over the entire tank depth. The results of pilot-scale tests for verification of the performance of an aerator equipped with a draft tube are presented. The full scale WWTP Leidsche Rijn, a compact “wrapped-around” Carrousel-3000 system where the draft tube technology is applied in a 7.5 metre deep basin, is described. Before the plant was put into operation a verification test for the aeration efficiency with clean water was carried out. The test showed that the draft tubes have no negative impact on the aeration efficiency of the surface aerators and justified the chosen design concept.

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MKRTCHYAN, Tariel Mher, and Evgenia N. SERPOKRILOV. "JUSTIFICATION OF DESIGN OF THE SELF-ROTATING AERATOR FOR GRAVITY NETWORK OF SEWERAGE." Urban construction and architecture 3, no. 4S (December 15, 2013): 51–52. http://dx.doi.org/10.17673/vestnik.2013.s4.15.

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А new aerators model has been design for urban wastewater networks. Aerator sets in manhole and rotates by wastewaters hydraulic pressure and friction force on the disc surface. As a result it is introduce a self-rotate system that follows by wastewaters aeration.

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Hao, Aimin, Sohei Kobayashi, Dong Xia, Qi Mi, Ning Yan, Mengyao Su, Aishou Lin, Min Zhao, and Yasushi Iseri. "Controlling Eutrophication via Surface Aerators in Irregular-Shaped Urban Ponds." Water 13, no. 23 (November 26, 2021): 3360. http://dx.doi.org/10.3390/w13233360.

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Surface aerators have often been introduced in urban ponds for esthetics, but their roles in remediating water quality are less understood. Effects of surface aerators on controlling eutrophication were examined in two urban ponds, in which anaerobic odors and cyanobacterial blooms had occurred and several aerators had been installed. In one of the ponds, a dramatic improvement in dissolved oxygen (DO) (from 1.8 to 8.1 mg L−1) and total phosphorus (TP) (from 1.6 to 0.4 mg L−1) was evident based on the comparison before and after the aeration. Although cyano-bloom did not occur, phytoplankton was dominated by cyanobacteria Microcystis species in both periods. Chlorophyll a (Chl-a) increased (from 29 to 51 μg L−1) and water transparency decreased (from 81 to 27 cm) after the aeration. In the other pond with an irregular shape, water quality was monitored two years after the installation to examine seasonal variation in trophic state and its spatial variation associated with aerator distribution. The water was mixed vertically well for the whole pond, as indicated by small surface-to-bottom differences in temperature. DO decreased in summer after rainfall but was always >5.7 mg L−1. Total nitrogen (TN) and TP were 0.8–2.3 and 0.03–0.07 mg L−1, respectively, and no cyano-blooms were observed across sites throughout the year. Phytoplankton was dominated by green algae and diatom species, which may be favored by the lower phosphorus level of the pond. Chl-a was higher and transparency was lower in the north side, which had more aerators and less shade from trees and buildings. These results suggest that surface aerators increased DO by vertical and horizontal mixing of water, reduced phosphorus release from sediment, and prevented cyano-bloom occurrence, but they did not improve Chl-a level and transparency. Rather, aeration can promote algal growth, and thus, additional purifying measures such as filtration and contact oxidation are required to further improve the trophic state of these ponds.

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Kells, James A., and C. D. Smith. "Reduction of cavitation on spillways by induced air entrainment." Canadian Journal of Civil Engineering 18, no. 3 (June 1, 1991): 358–77. http://dx.doi.org/10.1139/l91-047.

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Spillways for medium and high head dams may be exposed to high velocity flows and the associated destructive phenomenon of cavitation. Cavitation may occur at rough spots in the surface of the chute or tunnel, at local discontinuities in the finished surface such as construction joints, and at locations along critical flow profiles having significant deviations from design specifications. This paper addresses, on the basis of a review of the literature, a method for preventing or reducing cavitation damage on spillways through the use of spillway aerators. While the ability of induced or forced aeration to reduce or eliminate cavitation has been known for many years, it is only in relatively recent times that the aeration mechanism has been used to this advantage on spillways subject to high velocity flow. The recent application of aerators to spillway design is related, in part, to the trend toward higher head dams and larger design unit discharge rates. Design considerations and criteria for spillway aerators are presented in the paper, and the use of physical hydraulic models to make determinations of aerator performance is discussed. The intent of the paper is to provide a document with sufficient detail and scope to be useful as a first resource for spillway design practitioners. Key words: aerator design, air entrainment, cavitation, design criteria, high dam, model – prototype comparison, physical hydraulic model, spillway, spillway aeration.

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6

Xing, Pu, Ai Min Zhang, and Zhi Xiong Deng. "The Fluid-Structure Interaction Analysis of the Inverted Umbrella Aerator Curved Blade." Applied Mechanics and Materials 705 (December 2014): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amm.705.101.

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The blades are important components of the inverted umbrella aerators. In this paper, the inverted umbrella aerator blade with curved surface, which was arranged according to the variable helix angle of logarithmic spiral line, was designed and simulated. Through the simulation and calculation of the flow field of oxidation ditch that pushed by the blade, based on the fluid-structure interaction analysis, the reliability of the impeller blades has been studied. All the results showing that the new type inverted umbrella surface aerator blade is reliable.

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Rao, Achanta Ramakrishna, and Bimlesh Kumar. "Resistance Characteristics of Surface Aerators." Journal of Hydraulic Engineering 135, no. 1 (January 2009): 38–44. http://dx.doi.org/10.1061/(asce)0733-9429(2009)135:1(38).

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8

Rao, Achanta Ramakrishna, Ajey Kumar Patel, and Bimlesh Kumar. "Power characteristics of surface aerators." Journal of Chemical Technology & Biotechnology 85, no. 6 (March 3, 2010): 805–13. http://dx.doi.org/10.1002/jctb.2364.

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9

Qiu, Yong, Chi Zhang, Bing Li, Ji Li, Xiaoyuan Zhang, Yanchen Liu, Peng Liang, and Xia Huang. "Optimal Surface Aeration Control in Full-Scale Oxidation Ditches through Energy Consumption Analysis." Water 10, no. 7 (July 16, 2018): 945. http://dx.doi.org/10.3390/w10070945.

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Oxidation ditches are popularly used in rural areas and decentralized treatment facilities where energy deficiency is of concern. Aeration control technologies are well established for diffusion systems in order to improve energy efficiency, but there are still challenges in their application in oxidation ditches because surface aerators have unique characteristics with respect to oxygen transfer and energy consumption. In this paper, an integral energy model was proposed to include the energy, aeration, and fluidic effects of surface aerators, by which the energy for aeration of each aerator can be estimated using online data. Two types of rotating disks with different diameters (1800 mm and 1400 mm) were monitored in situ to estimate the model parameters. Furthermore, a feedforward–feedback loop control strategy was proposed using the concept of energy analysis and optimization. The simplified control system was implemented in a full-scale Orbal oxidation ditch, achieving an approximately 10% saving in full-process energy consumption. The cost–benefit analysis and carbon emission assessment confirmed the economic feasibility and environmental contribution of the control system. The energy model can help process designers and operators to better understand and optimally control the aeration process in oxidation ditches.

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10

Cancino, Beatriz, Pedro Roth, and Manfred Reuß. "Design of high efficiency surface aerators." Aquacultural Engineering 31, no. 1-2 (August 2004): 83–98. http://dx.doi.org/10.1016/j.aquaeng.2004.03.002.

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Cancino, Beatriz. "Design of high efficiency surface aerators." Aquacultural Engineering 31, no. 1-2 (August 2004): 99–115. http://dx.doi.org/10.1016/j.aquaeng.2004.03.003.

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Cancino, Beatriz. "Design of high efficiency surface aerators." Aquacultural Engineering 31, no. 1-2 (August 2004): 117–21. http://dx.doi.org/10.1016/j.aquaeng.2004.03.004.

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13

Rao, Achanta Ramakrishna, and Bimlesh Kumar. "Neural Modeling of Square Surface Aerators." Journal of Environmental Engineering 133, no. 4 (April 2007): 411–18. http://dx.doi.org/10.1061/(asce)0733-9372(2007)133:4(411).

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14

Deka, Kuldeep, Dipika Bordoloi, Amar J. Khound, Manas J. Bharali, and Racktackshree Chelleng. "A Review on Aeration Process and Different Types of Aerators Used in Various Aquaculture Systems." International Journal of Current Microbiology and Applied Sciences 11, no. 6 (June 10, 2022): 353–58. http://dx.doi.org/10.20546/ijcmas.2022.1106.039.

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In any aquaculture plant maintaining dissolve oxygen (DO) level is essential for the better health and survival of the living organisms present in the water body specially fish. DO level can be maintained by aeration process. The general idea behind aeration is to bring the water into intimate contact with the air. Either the water may be discharged into free air or the air may be forced into water. Aeration process also removes light volatile organic compounds, dissolve gases and fix odor, taste etc. in case of drinking water. Some common Apparatus used includes: low cascades, multiple jet fountains throwing water to considerable heights, spray nozzles discharging above the surface of a reservoir, superimposed trays or shelves, submerged perforated pipes, and porous tubes and plates.There are two ways, standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) of describing aerator performance. In selection of aerators for aeration in fish culture tank, durability and good standard aeration efficiency (SAE) value is too important moreover in case of aerators high standard oxygen transfer rate (SOTR) is important for the better growth of aquatic animals present in water. This article gives a review of different types of aerators used in aeration process based on various basis.

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15

Xu, Yi Min, Hong Xuan Yang, Wei Zhao, and Chun Ying Shen. "Study on the Air Pressure and the Backwater in the Cavity of Aerator on the Chute with an Anti-Arc Section." Advanced Materials Research 446-449 (January 2012): 2740–44. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2740.

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Aeration facility is widely used to reduce cavitation erosion of discharge works caused by high speed flows and it has proved to be an economical, effective and successful measure. For a flow chute with complex boundary conditions, the air pressure and backwater in an aerator cavity are important factors that influence the flow aeration, and there are numerous and complex hydraulic factors to affect them. By the jet trajectory equation and a series of experimental tests, the air pressure and backwater in different aerator cavities are investigated. How these factors such as the size and style of aerator, the arc radius of the chute and flow discharge to influence the air pressure and backwater in an aerator cavity are revealed. These results can be referenced in designing aerators on the chute with a concave surface.

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16

Rosso, D., L. E. Larson, and M. K. Stenstrom. "Surfactant effects on alpha factors in full-scale wastewater aeration systems." Water Science and Technology 54, no. 10 (November 1, 2006): 143–53. http://dx.doi.org/10.2166/wst.2006.768.

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Aeration is an essential process in the majority of wastewater treatment processes, and accounts for the largest fraction of plant energy costs. Aeration systems can achieve wastewater oxygenation by shearing the surface (surface aerators) or releasing bubbles at the bottom of the tank (coarse- or fine-bubble aerators). Surfactants accumulate on gas–liquid interfaces and reduce mass transfer rates. This reduction in general is larger for fine-bubble aerators. This study was conducted to evaluate mass transfer effects on the characterization and specification of aeration systems in clean and process water conditions. Tests at different interfacial turbulence regimes were analysed, showing higher gas transfer depression for lower turbulence regimes. Higher turbulence regimes can offset contamination effects, at the expense of operating efficiency. This phenomenon is characteristic of surface aerators and coarse bubble diffusers and is here discussed. The results explain the variability of α factors measured at small scale, due to uncontrolled energy density. Results are also reported in dimensionless empirical correlations that describe mass transfer as a function of physiochemical and geometrical characteristics of the aeration process.

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17

Kumar, Bimlesh, Neelam Verma, and Achanta Ramakrishna Rao. "METHODOLOGY TO CONSERVE ENERGY IN SURFACE AERATORS." Environmental Engineering and Management Journal 7, no. 2 (2008): 137–41. http://dx.doi.org/10.30638/eemj.2008.023.

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18

McWhirter, John R., Jia-Ming Chern, and Joesph C. Hutter. "Oxygen Mass Transfer Fundamentals of Surface Aerators." Industrial & Engineering Chemistry Research 34, no. 8 (August 1995): 2644–54. http://dx.doi.org/10.1021/ie00047a013.

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19

Lee, B. K., S. W. Sung, H. D. Chun, and J. K. Koo. "Automatic control for DO and pH in the activated sludge process in a coke wastewater treatment plant." Water Science and Technology 37, no. 12 (June 1, 1998): 141–48. http://dx.doi.org/10.2166/wst.1998.0524.

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The objective of this study is to develop an automatic control system for dissolved oxygen (DO) and pH of the activated sludge process in a coke wastewater treatment plant. A discrete type autotuned proportional-integral (PI) controller using an auto-regressive exogenous (ARX) model as a process model was developed to maintain the DO concentration in aerators by controlling the speed of surface aerators. Also a nonlinear pH controller using the titration curve was used to control the pH of influent wastewater. This control system was tested in a pilot scale plant. During this pilot plant experiment, there was small deviation of pH and the electric power consumption of surface aerators was reduced up to 70% with respect to the full operation when the DO set point was 2 mg/l. For real plant operation with this system, the discrete PI controller showed good tracking for set point change. The electricity saving was more than 40% of the electricity consumption when considering surface aerators. As a result of maintaining the DO constantly at the set point by the automatic control system, the fluctuation of effluent quality was decreased and overall improvement of the effluent water quality was achieved.

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20

Wei, Wenli, Yu Bai, and Yuling Liu. "Optimization of submerged depth of surface aerators for a carrousel oxidation ditch based on large eddy simulation with Smagorinsky model." Water Science and Technology 73, no. 7 (December 23, 2015): 1608–18. http://dx.doi.org/10.2166/wst.2015.638.

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This paper is concerned with the simulation and experimental study of hydraulic characteristics in a pilot Carrousel oxidation ditch for the optimization of submerged depth ratio of surface aerators. The simulation was based on the large eddy simulation with the Smagorinsky model, and the velocity was monitored in the ditches with an acoustic Doppler velocimeter method. Comparisons of the simulated velocities and experimental ones show a good agreement, which validates that the accuracy of this simulation is good. The best submerged depth ratio of 2/3 for surface aerators was obtained according to the analysis of the flow field structure, the ratio of gas and liquid in the bottom layer of a ditch, the average velocity of mixture and the flow region with a velocity easily causing sludge deposition under the four operation conditions with submerged depth ratios of 1/3, 1/2, 2/3 and 3/4 for surface aerators. The research result can provide a reference for the design of Carrousel oxidation ditches.

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21

Frey, W. "A Comparison of Different Aeration Systems." Water Science and Technology 25, no. 4-5 (February 1, 1992): 143–49. http://dx.doi.org/10.2166/wst.1992.0489.

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Aeration tests have been performed under operation conditions and in clean water in order to obtain information on the economy of different aeration systems. The results of investigations using jet aerators membrane diffusers and surface aerators are reported. The aeration tanks used for the tests were tanks with circulating mixed liquor. Typical α-values are reported for different systems tested and operational experiences are also included.

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22

Boyd, Claude E., and Harry V. Daniels. "Performance of Surface Aerators in Saline Pond Waters." Progressive Fish-Culturist 49, no. 4 (October 1987): 306–8. http://dx.doi.org/10.1577/1548-8640(1987)49<306:posais>2.0.co;2.

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23

Maier, W., and Kh Krauth. "Optimizing Nitrification in Aeration Basins with Surface Aerators." Water Science and Technology 20, no. 4-5 (April 1, 1988): 23–28. http://dx.doi.org/10.2166/wst.1988.0151.

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The detailed evaluation of the data from the daily logbooks of municipal clarification plants led to the finding that the nitrification capability of the plants is in essence dependent on the BOD5- and nitrogen sludge load. The evaluation of the data showed that, above all, aeration units with surface aerators did not operate well in respect to nitrification. Comprehensive investigations of different clarification plants led to the identification of shortages in the oxygen content of the aeration basins as the main reason for these deficiencies. The detailed examination of the results of these investigations shows clearly that in order to maintain low levels of ammonia nitrogen in the effluent, more attention must be paid to the factors influencing the oxygen concentration and distribution.

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24

Ognean, T. "Aspects concerning scale-up criteria for surface aerators." Water Research 27, no. 3 (March 1993): 477–84. http://dx.doi.org/10.1016/0043-1354(93)90048-m.

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25

Li, Xiangyang, Gengzhi Yu, Chao Yang, and Zai-Sha Mao. "Experimental Study on Surface Aerators Stirred by Triple Impellers." Industrial & Engineering Chemistry Research 48, no. 18 (September 16, 2009): 8752–56. http://dx.doi.org/10.1021/ie900623m.

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26

Rao, A. R., and B. Kumar. "Rectangular tank surface aerators: scale up criteria and energy conservation." International Journal of Environmental Science & Technology 3, no. 4 (September 2006): 425–33. http://dx.doi.org/10.1007/bf03325952.

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27

Patil, Swapnil S., Niteen A. Deshmukh, and Jyeshtharaj B. Joshi. "Mass-Transfer Characteristics of Surface Aerators and Gas-Inducing Impellers." Industrial & Engineering Chemistry Research 43, no. 11 (May 2004): 2765–74. http://dx.doi.org/10.1021/ie030428h.

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28

Rao, Achanta Ramakrishna, and Bimlesh Kumar. "The use of circular surface aerators in wastewater treatment tanks." Journal of Chemical Technology & Biotechnology 82, no. 1 (2006): 101–7. http://dx.doi.org/10.1002/jctb.1643.

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29

Demir, Ibrahim, Ismail Koyuncu, Serkan Guclu, Senol Yildiz, Vahit Balahorli, Suphi Caglar, Turker Turken, Mehmet E. Pasaoglu, Recep Kaya, and Reyhan Sengur-Tasdemir. "An Autopsy of Nanofiltration Membrane Used for Landfill Leachate Treatment." Scientific World Journal 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/850530.

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Komurcuoda leachate treatment plant, Istanbul, which consists of membrane bioreactor (MBR) and nanofiltration (NF) system, faced rapid flux decline in membranes after 3-year successful operation. To compensate rapid flux decline in membranes, the fouled membranes were renewed but replacement of the membranes did not solve the problem. To find the reasons and make a comprehensive analysis, membrane autopsy was performed. Visual and physical inspection of the modules and some instrumental analysis were conducted for membrane autopsy. Membranes were found severely fouled with organic and inorganic foulants. Main foulant was iron which was deposited on surface. The main reason was found to be the changing of aerator type of MBR. When surface aerators were exchanged with bottom diffusers which led to increasing of dissolved oxygen (DO) level of the basin, iron particles were oxidized and they converted into particulate insoluble form. It was thought that probably this insoluble form of the iron particles was the main cause of decreased membrane performance. After the diagnosis, a new pretreatment alternative including a new iron antiscalant was suggested and system performance has been recovered.

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Motta, Enrique J. "CHEMICAL ANALYSIS OF CO2REMOVAL IN TRAY AERATORS." Journal of the American Water Resources Association 31, no. 2 (April 1995): 207–16. http://dx.doi.org/10.1111/j.1752-1688.1995.tb03374.x.

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31

Rao, Achanta Ramakrishna, Bimlesh Kumar, and Ajey Kumar Patel. "Relative Performance of Different Shaped Surface Aeration Tanks." Water Quality Research Journal 42, no. 1 (February 1, 2007): 26–40. http://dx.doi.org/10.2166/wqrj.2007.005.

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Abstract Surface aeration experiments were conducted in tanks of length to width ratio (L/W) 1.0, 1.5 and 2 as well as circular tanks to study their relative performance on oxygen transfer and energy consumption while re-aerating deoxygenated water. An identical geometric similarity of various linear dimensions of aerators, rotor blades and rotor diameter was maintained for all sizes and shapes of aeration tanks tested. The power consumed per unit volume concept to simulate the oxygen transfer coefficient k was found to be valid for all three shapes of aerators. Simulation equations to predict the oxygen transfer coefficient k for any given dynamic parameter governing the theoretical power per unit volume, X, were developed for rectangular tanks of L/W ratios equal to 1.5 and 2. Results were compared with simulation equations (correlating k and X) for square and circular tanks. A simulation criterion correlating the oxygen transfer coefficient k with actual and effective power consumption per unit volume for three shapes of tanks was developed. Energy consumption per unit volume of water was also analyzed. Examples illustrating the application of results are presented. It has been found that the circular tanks are the most energy efficient, i.e., they produce maximum k for a given effective/actual input energy, followed by square tanks, rectangular tanks of L/W = 1.5 and rectangular tanks of L/W = 2. This suggests that the circular tank performs better as far as power requirements are concerned and hence provide better economy.

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Rosso, Diego, Lory E. Larson, and Michael K. Stenstrom. "Aeration of large-scale municipal wastewater treatment plants: state of the art." Water Science and Technology 57, no. 7 (April 1, 2008): 973–78. http://dx.doi.org/10.2166/wst.2008.218.

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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.

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Rao, A. R. K., and B. Kumar. "Scaling Up of the Geometrically Similar Unbaffled Circular Tank Surface Aerators." Chemical Engineering & Technology 31, no. 2 (February 2008): 287–93. http://dx.doi.org/10.1002/ceat.200700300.

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Da, Jinrong, Junxing Wang, Zongshi Dong, and Shuaiqun Du. "Hydraulic Characteristics of Lateral Deflectors with Different Geometries in Gentle-Slope Free-Surface Tunnels." Water 14, no. 17 (August 30, 2022): 2689. http://dx.doi.org/10.3390/w14172689.

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The gentle-slope tunnel has been adopted in many high dams, and aerators are usually required for high operating heads. For such tunnels, the lateral deflector is superior to the traditional bottom aerator, which loses its efficiency due to cavity blockage and fails to aerate the sidewalls. However, unfavorable flow patterns such as water-wings and shock waves are induced by the lateral deflectors. To address this problem, two novel lateral deflectors are proposed, and their hydraulic characteristics are comparatively investigated together with the triangular deflector by means of model test and numerical simulation. The triangular deflector was revealed to form a wide cavity that allows for the free rise up of the water-wings inside the cavity, leading to the development of a buddle-type shock wave, whereas the two-arc deflector yields a jet with a fluctuating surface, which induces water-wings and further develops into diamond-type shock waves. In contrast, the cavity formed behind the two-arc deflector with a straight downstream guiding line is stabler and shorter, thereby restricting the development of the rising flow and preventing the formation of water-wings and shock waves. Moreover, the two-arc deflector with a straight guiding line exhibits higher energy dissipation capacities and thus is recommended in practical engineering design.

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Rao, Achanta Ramakrishna, B. V. Bharathi Laxmi, and K. Subba Narasiah. "Simulation of Oxygen Transfer Rates in Circular Aeration Tanks." Water Quality Research Journal 39, no. 3 (August 1, 2004): 237–44. http://dx.doi.org/10.2166/wqrj.2004.033.

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Abstract Experiments were conducted to study the performance of circular and square tank surface aerators on the oxygen transfer coefficient and to a limited extent on power requirements. All the tanks are geometrically similar except for their shapes. They consist of a rotor of diameter, D, fixed with six flat blades rotating with a speed, N, in pure waters of viscosity, υ, at room temperature. A simulation equation to predict the oxygen transfer coefficient, k = KLa20(υ/g2)1/3 for any given dynamic parameter governing the theoretical power per unit volume, X = N3D2/(g4/3υ1/3) was developed for circular tank aerators. The data on square tank aerators support another such simulation equation developed earlier for square tanks. A comparison of results, while re-aerating the same volume of water in both the shapes of tanks, leads to the interesting conclusion that for a given rotor speed the oxygen transfer rate is substantially more in square tanks than in circular tanks; whereas for a given effective input power to the rotor the oxygen transfer rate is more in circular tanks than in square tanks. This suggests that square tanks are preferred to circular tanks to raise the oxygen concentrations at a faster rate, whereas the circular tanks are advantageous as far as power requirements are concerned.

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36

Lewis, William P., and Daniel W. Gay. "New Surface Aerators Reduced Yuba City's Oxygen Dissolution Power Draw by 33%." Proceedings of the Water Environment Federation 2003, no. 9 (January 1, 2003): 392–401. http://dx.doi.org/10.2175/193864703784639642.

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37

Chern, Jia-Ming, and Shun-Ren Chou. "Volatile Organic Compound Emission Rates from Mechanical Surface Aerators: Mass-Transfer Modeling." Industrial & Engineering Chemistry Research 38, no. 8 (August 1999): 3176–85. http://dx.doi.org/10.1021/ie990073v.

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38

Barnard, James L., and P. G. J. Meiring. "Dissolved Oxygen Control in the Activated Sludge Process." Water Science and Technology 20, no. 4-5 (April 1, 1988): 93–100. http://dx.doi.org/10.2166/wst.1988.0157.

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The increased cost of energy and the need for biological removal of plant nutrients resulted in a renewed interest in dissolved oxygen control in the activated sludge process. Back-up systems are required to prevent overaeration during the night which may be detrimental to the nutrient removal process. Full-scale experience with both fine bubble and surface aerators are described.

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39

Heduit, A., Ph Duchene, and L. Sintes. "Optimization of Nitrogen Removal in Small Activated Sludge Plants." Water Science and Technology 22, no. 3-4 (March 1, 1990): 123–30. http://dx.doi.org/10.2166/wst.1990.0192.

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In France, many small sewage treatment plants are of the activated sludge/extended aeration type and, generally, only receive a part of their nominal organic load. They are mostly equipped with surface aerators whose Standard wire Aeration Efficiency is in the range 1.3-1.9 kg 02 kwh−1. Consequently the sludge age and the supply of oxygen are sufficient to obtain a large elimination of nitrogen from domestic waste water even when the sludge temperature is low. However the concern is with the optimizing of the nitrogen treatment by the nitrification of ammonia in the aeration basin whilst avoiding any parasitic denitrification in the clarifier. Amongst other investigations, 4 small domestic wastewater treatment plants were studied over several months. A number of adjustment modifications were imposed on them in order to optimize the elimination of nitrogen : The final concentrations to be reached were : N-NH4− lower than 5 mg.l−1 and N-NO3− lower than 3 mg.l−1. The daily operating time of the aerators depends on the received load, the sludge concentration and the oxygenation capacity. When the works are under-loaded, the non-operational periods of the aerators should be as long as 1 1/2 and 2 hours in order to achieve the nitrates reduction. When the load is higher, the time required to attain anoxia after the shutdown of the aerators is shorter and the length of the non-operational periods can be reduced. These field experiments have allowed an evaluation of the tolerances around an optimum adjustment of the aeration operation : a reduction of 5 to 10 % of the daily aeration time may bring about an increase in the residual concentration of Kjeldahl nitrogen which reaches 10 rag.1−1. Conversely, sludge losses may take place in the clarifiers if the daily aeration time is increased by 5 to 10 % in the case of completely mixed basins equipped with slow vertical shaft aerators, and more than 15 % in the case of oxidation ditches (better denitrification probably due to the continuation of the current after stopping the rotors). The sludge concentration should be kept within fairly tight limits (± 0.5 g.1−1). It is however essential to rectify the aeration adjustments during the seasons : a rise in the sludge temperature of 10°C generates an increase in the total oxygen demand by 3 to 5 %. The particular case of plants with anoxic zone ahead is finally discussed.

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Sharma, Anurag, Thiyam Tamphasana Devi, and Bimlesh Kumar. "Turbulence in continuous flow surface aeration systems." Water Science and Technology 75, no. 5 (December 23, 2016): 1148–57. http://dx.doi.org/10.2166/wst.2016.607.

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Turbulence characteristics in an optimal continuous surface aeration system were investigated in this study. The experimental system consists of a rectangular tank, where flow is driven by equally spaced aerators placed on the liquid surface. The mass-transfer coefficient and turbulent parameters at the tank's inlet and outlet were measured to enable analysis of their interdependent relationships. The turbulence parameters are linked closely to the system's mass-transfer process. Turbulent bursting analysis has shown that ejection and sweep events govern the hydrodynamics of the systems. Turbulent intensity increases with increasing speed of rotation, and consequently the mass-transfer coefficient also increases. The universal probability distribution functions of the velocity fluctuations in continuous flow surface aeration systems follow the Gram-Charlier series, based on exponential distribution, and the theoretical and experimental curves match.

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Suescun, J., and E. Ayesa. "Practical identification of the dissolved oxygen dynamic in activated sludge plants." Water Science and Technology 45, no. 4-5 (February 1, 2002): 397–404. http://dx.doi.org/10.2166/wst.2002.0634.

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This paper presents the application to a full-scale waste water treatment plant (WWTP) of a practical methodology to identify the oxygen supply and consumption terms, which regulate the dynamic behaviour of the dissolved oxygen concentration (SO) in activated sludge reactors. This methodology is based on a periodic adjustment of the selected model for oxygen mass-transfer coefficient (KLa) and a continuous estimation of the oxygen uptake rate (rO), maintaining constant the adjusted KLa model, in order to uncouple the effects that the consumption and supply terms have on the SO concentration. The adjustment phase of the KLa model is based on typified excitations of the system through the aeration system of the plant, which allow the estimation of KLa for different values of the aeration intensity parameter, for instance, air flow rate in air diffusion systems, revolution speed in surface aerators, etc. Once the KLa model is adjusted, it is possible to evaluate the KLa value in process conditions at any time. The continuous estimation of rO is carried out starting from the oxygen mass balance in the activatedsludge reactor. This practical methodology has been successfully verified in the Badiolegi WWTP in Azpeitia (Spain), which biological process consists of a double stage AB process, with two different aeration systems: fine pore air diffusers in the A-stage and surface aerators in the B-stage.

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Parker, Wayne J., Hugh D. Monteith, John P. Bell, and Henryk Melcer. "A field scale evaluation of the airstripping of volatile organic compounds by surface aerators." Water Environment Research 68, no. 7 (November 1996): 1132–39. http://dx.doi.org/10.2175/106143096x128531.

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Moulick, Sanjib. "Discussion of “Resistance Characteristics of Surface Aerators” by Achanta Ramakrishna Rao and Bimlesh Kumar." Journal of Hydraulic Engineering 136, no. 3 (March 2010): 193. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000115.

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Rao, Achanta Ramakrishna, and Bimlesh Kumar. "Closure to “Resistance Characteristics of Surface Aerators” by Achanta Ramakrishna Rao and Bimlesh Kumar." Journal of Hydraulic Engineering 136, no. 3 (March 2010): 193. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000166.

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Fan, Long, Nong Xu, Zhiqiang Wang, and Hanchang Shi. "PDA experiments and CFD simulation of a lab-scale oxidation ditch with surface aerators." Chemical Engineering Research and Design 88, no. 1 (January 2010): 23–33. http://dx.doi.org/10.1016/j.cherd.2009.07.013.

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Mkrtchyan, Tariel Mgerovich, and Garegin Galikovich Petrosyan. "STATUS AND PROSPECTS OF WASTEWATER SYSTEMS RENOVATION IN THE REPUBLIC OF ARMENIA." Urban construction and architecture 4, no. 1 (March 15, 2014): 62–66. http://dx.doi.org/10.17673/vestnik.2014.01.11.

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Information about the main directions of wastewater systems renovation in the Republic of Armenia is presented. The apparatus for receiving of surface flow in sewage system is proposed. This mechanism provides an opportunity to roll back the following monitored indexes: organic material concentration, dissolved oxygen, oxidationreduction potential, oxygen uptake rate by active sludge. The research points at adequate security of biomass by oxygen in the process of aeration and at practicability of use of ceramic aerators from armenian tuff for the first stage of wastewater systems renovation.

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Ognean, T. "A New Dimensionless Criterion for the Oxygen Transfer Efficiency in Both Surface and Subsurface Aeration Systems." Water Science and Technology 26, no. 9-11 (November 1, 1992): 2531–34. http://dx.doi.org/10.2166/wst.1992.0780.

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The effect of power consumption on oxygen transfer efficiency has been evaluated in both surface and subsurface aeration systems. For this purpose a new dimensionless number To, named “efficiency criterion”, has been proposed.Using this number, the efficiency of different aeration systems could be compared.The comparison has been achieved by taking into consideration the data furnished by full-scale experimental models.The results have proved that of two aerators with identical diameters and the same rotational velocity reaching the maximum To, the one with a higher power consumption had a higher efficiency.The results regarding the subsurface aeration systems show that the efficiency of aeration equipment can be continuously increased if the bubbles' diameters are decreased.

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Cosby, Gary M., and Daniel W. Gay. "CLEAN WATER TESTING OF INNOVATIVE SURFACE AERATORS PROMISES SIGNIFICANT SAVINGS FOR CHATTANOOGA'S MOCCASIN BEND WWTP." Proceedings of the Water Environment Federation 2003, no. 5 (January 1, 2003): 272–81. http://dx.doi.org/10.2175/193864703784607124.

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Mæhlum, T. "Treatment of landfill leachate in on-site lagoons and constructed wetlands." Water Science and Technology 32, no. 3 (August 1, 1995): 129–35. http://dx.doi.org/10.2166/wst.1995.0134.

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On-site “high-tech” leachate treatment systems are often avoided due to large construction and operation costs. Alternative integrated methods need to be examined. This paper describes a biological treatment system, capturing leachate from a municipal sanitary waste (MSW) landfill on-site. The area has a typical cool temperate continental climate. The treatment system is built in a ravine and has been operating since July 1993. The average flow is estimated to be 120 m3 d−1. The low-strength leachate is first treated in a 400 m3 anaerobic pond. Stage 2 is a 4000 m3 aerated lagoon with 3 AIRE-O2 aspirator propeller aerators/mixers. Oxidation of organic matter, NH4-N and Fe take place in this lagoon. Stage 3 is two parallel constructed wetlands (CWs) with horizontal subsurface flow, each with an area of 400 m2. The filters consist of (i) washed gravel and (ii) Light Expanded Clay Aggregates, LECA (size range 10-20 mm). The CWs were planted with Phragmites australis and Typha latifólia. Stage 4 is a 2000 m2 free water surface CW, planted with Scirpus and Typha. The integrated system has no moving parts, except for the aerators. The overall removal of organic matter, N, P, Fe and pathogenes is promising (70-95%). The paper presents combinations with the use of conventional and natural systems in MSW landfill leachate treatment.

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Kaul, S. N., T. Nandy, and L. Szpyrkowicz. "Scale-Up Formulations for Radial and Pitch Blade Surface Aerators for Oxygenation Capacity and Power Requirements." International Journal of Environmental Studies 59, no. 2 (January 2002): 255–65. http://dx.doi.org/10.1080/00207230210920.

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Journal articles on the topic 'Surface Aerators'

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