Academic literature on the topic 'Aeration efficiency'
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Journal articles on the topic "Aeration efficiency"
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Azman, A., M. H. Zawawi, N. H. Hassan, A. Abas, N. A. Razak, A. Z. A. Mazlan, and M. A. Z. Mohd Remy Rozainy. "Effect of Step Height On the Aeration Efficiency of Cascade Aerator System Using Particle Image Velocimetry." MATEC Web of Conferences 217 (2018): 04005. http://dx.doi.org/10.1051/matecconf/201821704005.
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Aeration is an important parameter in water filtration system as it allows the transfer of oxygen to water through turbulence effect which subsequently increases air entrainment in the water. For water treatment application, aeration efficiency is measured to ensure continuous re-oxygenation of the unfiltered water. Aside from aeration, this paper also studies the flow patterns through the use of particle image velocimetry (PIV) setup. Through the use of real scale down physical model laboratory study is performed using PIV to obtain the velocity profile. These velocity profiles will then be used to calculate the aeration efficiency of the water in a cascade aerator system. Based on the findings, the aeration efficiency obtained from the PIV experiment has a maximum value at the lowest point of the cascade aerator system with a value of 0.0139 due to increase in mass flow rate as it moves through the steps with velocity of 0.418 m/s. Therefore, in the design of a cascade aerator system, it is advisable to increase the number of steps since it will increase the aeration efficiency of the system.
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Deng, Feng, and Rui Zhang. "Research on COD Removal and SOUR of Aerobic Granule with Intermittent Aeration in Continuous Flow System." Advanced Materials Research 518-523 (May 2012): 478–84. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.478.
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The impact of intermittent aeration on aerobic granular sludge in a continuous flow reactor was studied. Nine intermittent aeration modes were set up to investigate the change of DO, pH, COD removal efficiency and SOUR. The results showed DO and pH had different change tendencies. The 3-1 mode was the optimal mode under these experiment conditions. In aerating stage, the highest COD removal efficiency could achieve 96.32%. Stopping aeration for one hour, COD removal efficiency could still reach at 90.20%. This operation mode could save about 25% energy consumption theoretically. The comparison of SOUR between continuous aeration and 4-2 mode showed that the intermittent aeration had little effect on granular sludge activity. The theory of stress & damage and unbalanced growth could explain this appearance.
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Lindam, John. "Aeration Efficiency in Oxidation Ditches." Proceedings of the Water Environment Federation 2013, no. 3 (January 1, 2013): 387–400. http://dx.doi.org/10.2175/193864713813503413.
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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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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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Ozkan, Fahri, M. Cihat Tuna, Ahmet Baylar, and Mualla Ozturk. "Optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits." Water Science and Technology 70, no. 5 (July 3, 2014): 871–77. http://dx.doi.org/10.2166/wst.2014.305.
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Oxygen is an important component of water quality and its ability to sustain life. Water aeration is the process of introducing air into a body of water to increase its oxygen saturation. Water aeration can be accomplished in a variety of ways, for instance, closed-conduit aeration. High-speed flow in a closed conduit involves air-water mixture flow. The air flow results from the subatmospheric pressure downstream of the gate. The air entrained by the high-speed flow is supplied by the air vent. The air entrained into the flow in the form of a large number of bubbles accelerates oxygen transfer and hence also increases aeration efficiency. In the present work, the optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits was studied experimentally. Results showed that aeration efficiency increased with the air-demand ratio to a certain point and then aeration efficiency did not change with a further increase of the air-demand ratio. Thus, there was an optimum value for the air-demand ratio, depending on the Froude number, which provides maximum aeration efficiency. Furthermore, a design formula for aeration efficiency was presented relating aeration efficiency to the air-demand ratio and Froude number.
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Sukadana, Ida Bagus Putu, I. Made Rajendra, Ida Ayu Anom Arsani, and I. Wayan Suastawa. "PERFORMANCE ANALYSIS OF 4-OUTLETS SPRAY AERATOR FOR PROCESSING OF INDIGOFERA LEAVES (Indigofera Tinctoria Linn) BECOMES NATURAL DYE SUBSTANCES." Jurnal Bahan Alam Terbarukan 6, no. 2 (October 24, 2017): 76–86. http://dx.doi.org/10.15294/jbat.v6i2.8045.
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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%.
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Kasakura, Tadao, Yoshiho Tomita, Kiwamu Matsubara, and Atsushi Kubo. "A Basic Study of the Efficiency of Spiral Flow Aeration." Water Science and Technology 23, no. 10-12 (May 1, 1991): 1951–60. http://dx.doi.org/10.2166/wst.1991.0651.
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The oxygen transfer efficiency of spiral flow aeration is affected by many factors, for example, the shape of aeration tank, the type of diffuser, the air flow rate and so on. The authors tried to determine the relationship between these factors and the efficiency of aeration. We found these factors were restricted by some independent variables, so we analyzed quantitatively the relationship between these variables and the efficiency of aeration based on data from the full scale experiments on spiral flow aeration using porous ceramic diffusers. Regression equations show that the efficiency of the spiral flow aeration would be higher with a reduction of the air feed rate per tank volume and an increase of the total bubbling area of the diffusers. Other variables would not so greatly affect efficiency.
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E. Khalaf, Anfal, and Mohammed A. Rashid. "PERFORMANCE EVALUATION OF LOCALLY FABRICATED MECHANICAL SURFACE AERATOR." Journal of Engineering and Sustainable Development 25, Special (September 20, 2021): 3–213. http://dx.doi.org/10.31272/jeasd.conf.2.3.21.
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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.
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Cihat Tuna, M., Fahri Ozkan, and Ahmet Baylar. "Experimental investigations of aeration efficiency in high-head gated circular conduits." Water Science and Technology 69, no. 6 (January 20, 2014): 1275–81. http://dx.doi.org/10.2166/wst.2014.021.
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The primary purpose of water aeration is to increase the oxygen saturation of the water. This can be achieved by using hydraulic structures because of substantial air bubble entrainment at these structures. Closed conduit aeration is a particular instance of this. While there has been a great deal of research on air-demand ratio within closed conduit, very little research has specifically addressed aeration efficiency of closed conduit. In the present work an experimental study was conducted to investigate the aeration efficiency of high-head gated circular conduits. Results showed that high-head gated circular conduits were effective for oxygen transfer. The effects of Froude number and ratio of the water cross-sectional flow area to the conduit cross-sectional area on aeration efficiency were particularly significant, whereas the effect of conduit length was only moderate. Further, a design formula for the aeration efficiency was presented relating the aeration efficiency to ratio of water cross-sectional flow area to conduit cross-sectional area and Froude number. The obtained results will be useful in future modeling processes and aid the practicing engineer in predicting aeration efficiency for design purposes.
Dissertations / Theses on the topic "Aeration efficiency"
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SINGH, KANCHAN. "STUDY OF AERATION EFFICIENCY OVER THE PIANO KEY WEIRS." Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18799.
Full textAbstract:
Aeration is the process of increasing the dissolved oxygen content of water, which is an
important water quality parameter for the survival of flora and fauna on this planet. The
dissolved oxygen level can be increased using hydraulic structures or by installing mechanical
aerators. Hydraulic structures proved to be an economical and efficient way of enhancing the
aeration process, thereby increasing the dissolved oxygen in the water stream. It develops large
amounts of air bubbles; as a result, contact surface area increases, and hence the water-air -mass
transfer accelerates. Weirs are having the highest aeration efficiency among all hydraulic
structures. Various researchers study the aeration process involved in weirs and various
experiments have been done to study the parameters involved. As literature said that the
aeration efficiency of the different hydraulic structures depends on their geometry. According
to past studies, the researchers have stated that the hydraulic structures help enhance the
dissolved oxygen of the water body. Rivers clean themselves naturally after movement over a
certain distance by the process of aeration. It is also known as the self-cleaning nature of rivers.
Weirs also follow the same process for cleaning as well as maintaining the various water quality
parameters. They function in the same manner as rivers naturally perform the self-cleansing
process for its purification. In the self-cleansing process, the river clears itself and maintains
various water quality parameters. In order to enhance the DO content of the water body (river,
dams, and reservoirs), an experimental study was conducted in Fluid Mechanics and Hydraulic
Laboratory at the Delhi Technological University. The primary goal of this research was to
increase the DO content of the water body through aeration. The author conducted an
experimental study over three different types (Type-A, Type-B, and Type-C) of Piano Key Wier
models and compared them to achieve this goal. The present study's findings conclude that the
aeration of the free-flowing water can be enhanced by constructing hydraulic structures across
the stream or river.
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Sundberg, Cecilia. "Improving compost process efficiency by controlling aeration, temperature and pH /." Uppsala : Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005103.pdf.
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Odize, Victory Oghenerabome. "Diffuser Fouling Mitigation, Wastewater Characteristics And Treatment Technology impact on Aeration Efficiency." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82852.
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Achieving energy neutrality has shifted focus towards aeration systems optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. The activated sludge wastewater treatment process is dependent on aeration efficiency which supplies the oxygen needed in the treatment process. The process is a complex heterogeneous mixture of microorganisms, bacteria, particles, colloids, natural organic matter, polymers and cations with varying densities, shapes and sizes. These activated sludge parameters have different impacts on aeration efficiency defined by the OTE, % and alpha.
Oxygen transfer efficiency (OTE) is the mass of oxygen transferred into the liquid from the mass of air or oxygen supplied, and is expressed as a percentage (%). OTE is the actual operating efficiency of an aeration system. The alpha Factor (α) is the ratio of standard oxygen transfer efficiency at process conditions (αSOTE) to standard oxygen transfer efficiency of clean water (SOTE). It is also referred to as the ratio of process water volumetric mass transfer coefficient to clean water volumetric mass transfer coefficient. The alpha factor accounts for wastewater contaminants (i.e. soap and detergent) which have an adverse effect on oxygen transfer efficiency. Understanding their different impacts and how different treatment technologies affect aeration efficiency will help to optimize and improve aeration efficiency so as to reduce plant operating costs.
A pilot scale study of fine pore diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha measurement were performed at Blue Plains, Washington DC. In the study a mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2) to mitigate fouling, while two diffusers were kept as a control with no reverse flexing. A 45 % increase in DWP of the control diffuser after 17 month of operation was observed, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show any significant increase in DWP, and in comparison to the control diffuser prevented a 35 % increase in DWP. Hence, the RF fouling mitigation technique potentially saved blower energy consumption by reducing the pressure burden on the air blower and the blower energy requirement. However, no significant impact of the RF fouling mitigation treatment technique in preventing a decrease in alpha-fouling (𝝰F) of the fine pore diffusers over time of operation was observed. This was because either the RF treatment method maintained wide pore openings after cleaning over time, or a dominant effect of other wastewater characteristics such as the surfactant concentration or particulate COD could have interfered with OTE.
Further studies on the impact of wastewater characteristics (i.e., surfactants and particulate COD) and operating conditions on OTE and alpha were carried out in another series of pilot and batch scale tests. In this study, the influence of different wastewater matrices (treatment phases) on oxygen transfer efficiency (OTE) and alpha using full-scale studies at the Blue Plains Treatment Plant was investigated. A strong relationship between the wastewater matrices with oxygen transfer characteristics was established, and as expected increased alphas were observed for the cleanest wastewater matrices (i.e., with highest effluent quality). There was a 46 % increase in alpha as the total COD and surfactant concentrations decreased from 303 to 24 mgCOD/L and 12 to 0.3 mg/L measured as sodium dodecyl sulphate (SDS) in the nitrification/denitrification effluent with respect to the raw influent. The alpha improvement with respect to the decrease in COD and surfactant concentration suggested the impact of one or more of the wastewater characteristics on OTE and alpha.
Batch testing conducted to characterize the mechanistic impact of the wastewater contaminants present in the different wastewater matrices found that the major contaminants influencing OTE and alpha were surfactants and particulate/colloidal material. The volumetric mass transfer coefficient (kLa) measurements from the test also identified surfactant and colloidal COD as the major wastewater contaminants present in the influent and chemically enhanced primary treatment (CEPT) effluent wastewaters impacting OTE and alpha. Soluble COD was observed to potentially improve OTE and alpha due to its contribution in enhancing the oxygen uptake rate (OUR). Although the indirect positive impact of OUR on alpha observed in this study contradicts some other studies, it shows the need for further investigation of OUR impacts on oxygen transfer. Importantly, the mechanistic characterization and quantitative correlation between wastewater contaminants and aeration efficiency found in this study will help to minimize overdesign with respect to aeration system specification, energy wastage, and hence the cost of operation. This study therefore shows new tools as well as the identification of critical factors impacting OTE and alpha in addition to diffuser fouling.
Gas transfer depression caused by surfactants when they accumulate at the gas-liquid interface during the activated sludge wastewater treatment process reduces oxygen mass transfer rates, OTE and alpha which increases energy cost. In order to address the adverse effect of surfactants on OTE and alpha, another study was designed to evaluate 4 different wastewater secondary treatment strategies/technologies that enhances surfactant removal through enhanced biosorption and biodegradation, and to also determine their effect on oxygen transfer and alpha. A series of pilot and batch scale tests were conducted to compare and correlate surfactant removal efficiency and alpha for a) conventional high-rate activated sludge (HRAS), b) optimized HRAS with contactor-stabilization technology (HRAS-CS), c) optimized HRAS bioaugmented (Bioaug) with nitrification sludge (Nit S) and d) optimized bioaugmented HRAS with an anaerobic selector phase technology (An-S) reactor system configuration. The treatment technologies showed surfactant percentage removals of 37, 45, 61 and 87 %, and alphas of 0.37 ±0.01, 0.42 ±0.02, 0.44 ±0.01 and 0.60 ±0.02 for conventional HRAS, HRAS-CS, Bioaug and the An-S reactor system configuration, respectively. The optimized bioaugmented anaerobic selector phase technology showed the highest increased surfactant removal (135 %) through enhanced surfactant biosorption and biodegradation under anaerobic conditions, which also complemented the highest increased alpha (62 %) achieved when compared to the conventional HRAS. This study showed that the optimized bioaugmented anaerobic selector phase reactor system configuration is a promising technology or strategy to minimize the surfactant effects on alpha during the secondary aeration treatment stagePh. D.
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Fredericks, Dana Kathleen. "Optimization of intermittent aeration for increased nitrogen removal efficiency and improved settling." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50427.
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Nitrogen, when present in excess, can cause eutrophication in waterways, which may result in hypoxia and the desertion or death of aquatic life. As nitrogen continues to pollute our water, wastewater discharge limits are becoming more stringent with effluent limits based on preserving receiving waters.
This project took place at the Hampton Roads Sanitation District's, Chesapeake-Elizabeth Wastewater Treatment Plant; a High-Rate Activated Sludge (HRAS) plant with no primary clarifiers operating at an SRT of 1.5" 2 days without biological nitrogen removal (BNR). BNR is considered more cost-effective than comparable chemical and physical processes, but it requires considerable resources to meet increasingly strict discharge limits. As these limits decrease, the resource requirement increases, making them no longer cost-effective. By 2021 HRSD anticipates the plant will be included in a bubble permit, resulting in a total nitrogen (TN) effluent target of approximately 5-8 mg/L. Conventional BNR plants remove carbon and nitrogen simultaneously, which requires both increased volume (capital costs) and aeration energy demand (operating costs). As an alternative, HRSD is pilot testing an A/B process; a two-sludge system comprised of a carbon removal stage followed by a nitrogen removal stage. The very high rate, low dissolved oxygen (DO) A-stage could reduce the organic load, allowing the B-stage to perform BNR within the existing reactor volume and eliminating the need for primary clarifiers. However, improper control of the carbon removal system can lead to carbon and alkalinity deficiencies, which results in poor nitrogen removal. This is mediated by employing a short-cut nitrogen removal technology.
A novel aeration strategy based on set-points for reactor ammonia, nitrite and nitrate concentrations with the aim of maintaining equal effluent ammonia and nitrate + nitrite (NOx) concentrations was successfully employed. The goal was to inhibit nitrite-oxidizing bacteria (NOB) so the nitrification process stopped at nitrite. This helps promote an effluent with equal parts ammonia and nitrite, which is amenable to anammox polishing to achieve low effluent nitrogen concentrations. NOB suppression has been successfully applied in sidestream anaerobic digestion waste streams because NOB out-selection is favored in warm, nitrogen-rich conditions. However, the cold, dilute conditions of continuous mainstream processes are not favorable to NOB out-selection. The mechanisms employed to achieve sidestream NOB out-selection are not reasonable for mainstream applications. This study employed operational and process control strategies to aggressively out-select NOB based on optimizing the chemical oxygen demand (COD) input, imposing transient anoxia, aggressive solids retention time (SRT) operation approaching ammonia oxidizing bacteria (AOB) washout, and a dissolved oxygen concentration (DO) of 1.5 mg O2/L during aeration. This pilot-scale study demonstrated that when run aggressively, the proposed online aeration control is able to out-select NOB in mainstream conditions and provide relatively high nitrogen removal without supplemental carbon and alkalinity at a low hydraulic retention time (HRT). Successful full-scale implementation would promote improved water quality that is economically sustainable.
The ability of two different process configurations (full intermittent aeration and Modified Ludzak-Ettinger [MLE]) to achieve high nitrite accumulation and nitrogen removal efficiencies in four equal volume tanks in series followed by a cone-bottom clarifier in a pilot scale biological nitrogen removal (BNR) process (V=0.61 m3) was evaluated. All four biological reactors were equipped with a variable speed mixer, a 17.7 cm membrane disc diffuser, and a Hach LDO probe. Aeration capacity in all four tanks allowed the system to be operated with or without a defined anoxic zone. Both processes utilized a novel aeration strategy based on set-points for reactor ammonia, nitrite and nitrate concentrations with the aim of maintaining equal effluent ammonia and NOx concentrations. The B-stage had a variable HRT (2-7 hours) and a variable influent flow rate. When operating in the MLE configuration, an internal mixed liquor recycle (IMLR) line returned nitrified mixed liquor from the last aerobic reactor to the anoxic reactor using a peristaltic pump at a rate between 200-450% of the influent flow. When IMLR was used the first tank was not aerated. RAS from the clarifier was returned to the anoxic zone at 100% of the influent flow. SRT was controlled by wasting solids from the last aerobic tank. The wasting was automated to maintain desired SRT.
The nitrite accumulation ratio (NAR), NO2- -N/(NO2- -N+ NO3- -N), was best under full intermittent aeration, achieving 0.43+0.10 at a 3 hour HRT and influent carbon to ammonia ratio (COD/NH4+-N) of 7.9+1.4. As an MLE, the NAR decreased with increasing internal mixed liquor return (IMLR); at IMLR of 200%, 325% and 450%, the NAR was 0.20+0.04, 0.17+0 and 0.14+0.03, respectively. The MLE did, however, improve the overall TIN removal efficiency compared to operation where all reactors were intermittently aerated. The TIN removal efficiency was best under MLE operation, increasing as the IMLR and influent COD/NH4+-N increased. When the IMLR was 200%, 325% and 450%, the TIN removal efficiencies were 76.4+4.0%, 80.2+0% and 86.3+5.0%, respectively, which corresponded to an influent COD/NH4+-N and HRT of 9.2+0.8 and 4 hr, 9.8+0.4 and 6 hr, and 10.3+1.2 and 6 hr, respectively.
In addition to process operation, key issues of filamentous bulking were assessed. Concrete solutions to this continual issue are not available as the unique features of each plants influent and process dynamics prohibit the formulation of a universal solution. Filaments observed throughout this study included Type 0041, Type 0675, Type 0803, Nocardia, Thiothrix I and Thiothrix II. Type 0041 and Type 067 were observed throughout the study and are typical of BNR systems; they arguably do not contribute to settling issues. Type 0803 filaments are linked to low F/M, high SRT systems. It was present at the start of the experiment and then no longer detected. Nocardia made a brief appearance on day 72 causing temporary foaming issues. This was fixed by vacuuming the surface of the clarifier daily and may be attributed to the high surface area to volume ratio present in pilot-scale systems. Thiothrix I and Thiothrix II were observed after day 93, however, never as the dominant species. Thiothrix related bulking was observed in the A-stage (Miller et al, 2012), which was attributed to high sulfide and organic acids in the influent raw wastewater during high temperature periods and carryover of sulfide and Thiothrix from the over-sized A-stage clarifier. The goals of this evaluation were to identify favorable parameters of common filaments and establish their impacts on the system. Typically an SVI of 150 mL/g indicates good settling. Overall the study experienced good settling (128.3+36.3 mL/g), indicating that operating under different influent substrate concentrations and process configurations did not result in poor settling.Master of Science
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McCann, Brian Patrick. "The efficiency of aeration and COD removal of a modified rotating biological contractor." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333844.
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Kowsari, Assieh. "Analysis of design factors influencing the oxygen transfer efficiency of a Speece Cone hypolimnetic aerator." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/4168.
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The objective of this research was to characterize the performance of a
downflow bubblecontact (DBCA) hypolimnetic aerator —
Speece Cone-. The effect of two key design
factors, inlet water velocity and the ratio of gas flow rate to water flow rate on four
standard units of measure was examined: (a) the Oxygen Transfer Coefficient, KLa,
corrected to 20°C, KLa₂₀ (hr-¹), (b) the Standard Oxygen Transfer Rate, SOTR (g0₂.hr-¹)
(c) the Standard Aeration Efficiency, SAE (gO₂kWhr-¹), and (d) the Standard Oxygen
Transfer Efficiency, SOTE (%). Two sources of oxygen, Pressure Swing Adsorption
(PSA) oxygen (87% purity) and air, were compared.
KLa₂₀, SOTR, and SAE increased with an increase in the ratio of gas flow rate to water
flow rate for both air and oxygen, over a range of 0.5% to 5.0%; while SAE deceased. An
increase in inlet water velocity resulted in a decrease in KLa, corrected to 20°C, SOTR,
and SAE, but an increase in the SOTE. Treatments on air showed similar, but much less
dramatic effect of the gas flow rate to water flow rate ratio and water inlet velocity on
KLa₂₀, SOTE, SAE, and SOTE, when compared to treatments on PSA oxygen.
The best performance was achieved with an inlet water velocity of 6.9-7.6 ms-¹ and
oxygen flow rate to water flow rate ratio of about 2.5%. At this combination, the SOTE
was about 66-72%.
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Alsys, Aivaras. "Mechaninių ir pneumatinių aeratorių efektyvumo analizė." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080930_090621-65016.
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Baigiamajame magistro darbe nagrinėjamos pneumatinių bei mechaninių aeravimo sistemų problemos, jų konstrukcijos. Taip pat išnagrinėti veiksniai įtakojantys aeratorių efektyvumą. Išnagrinėjus konstrukcijas pasirinkti 3 aeratoriai su kuriais atlikti eksperimentai bei įvertintas jų efektyvumas. Darbą sudaro 8 dalys: įvadas, tyrimo objektas ir problemos aprašymas, tiriamųjų aeravimo sistemų apžvalga bei konstrukcijų analizė, mechaninių ir pneumatinių aeravimo sistemų efektyvumo analizė, tyrimo metodika bei eksperimentinis stendas, tyrimo rezultatai, išvados, literatūros sąrašas.The following masters work consists of the analyse of the pneumatic and mechanical aeration systems, these problems and construction. Also explored factors who does influence for the efficiency of the aerators. When the constructions were explored, 3 aerators were selected, the experiments was made and valuated the efficiency. There are 8 chapters: introduction, the object of the analys and description of the problem, review of the explored aeration systems and analys of the constructions, efficiency analysis of mechanical and pneumatic aeration systems, methodology of the analysis and case of the experiment, results of the analysis, conclusions and suggestions, the list of the literature.
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Khayi, Noureddine. "Deammonification efficiency in combined UASB and IFAS system for mainstream WWT." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210809.
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The study is about Nitrogen removal from the low concentrated mainstream wastewater after Upflow Anaerobic Sludge Blanket reactor process (UASB) by single-stage Partial Nitritation/Anammox process in a pilot scale reactor at Hammarby Sjöstad in Stockholm. A mixture of various concentrations of dissolved oxygen and different aeration methods have been tested in the pilot scale reactor in five months divided into five periods where the temperature was set at 15° C throughout the study. The best result was in period 4, the average nitrogen removal efficiency was 52% varying between 40 and 60 % with aeration method of the ratio R = 1/3 (R = 20 minutes with aeration to 40 minutes without aeration) and a dissolved oxygen concentration of 1.3 mg/L. Partial nitritation/Anammox is considered more environmentally friendly due to reduced energy requirements for aeration, no need for an external carbon source. The process also allows for a more cost-effective nitrogen removal from wastewater.Vatten är nödvändigt för existensen av allt liv på jorden och spelar en avgörande roll i alla mänskliga aktiviteter. Antropogena aktiviteter förorenar denna viktiga resurs och medför stor risk för människors och djurs hälsa samt växter. Kvävebelastning från jordbruket och avloppsvatten i mark- eller vattenmiljön har resulterat till övergödning, vilket är ett miljö- och ekonomiskt problem på grund av en obalans mellan ekosystemtillförseln och den naturliga näringsförbrukningen. I denna studie behandlades avloppsvatten i en pilotskala reaktor med en integrerad fastfilm aktiverat slam (IFAS) som drivs med ett enstegs partial nitritation/Anammox-process. Kväverening från den lågkoncentrerade huvudström avloppsvatten efter Uppflöde Anaerob Slam Blankett reaktor process (UASB) undersöktes. En blandning av olika koncentrationer av upplöst syre och olika luftningsmetoder har testats i pilotskala reaktorn i fem månader uppdelad i fem perioder där temperaturen sattes vid 15° C under hela studien. De bästa resultaten i kväve reningseffektivitet var 52 % i genomsnitt i period 4 varierande mellan 40 och 60 %, luftningsmetod med ett förhållande av R = 1/3 (R = 20 minuter med luftning till 40 minuter utan luftning) och ett upplöst syre Koncentration av 1,3 mg/l. Jämförelsen tog hänsyn till alla former av utsläpp av kväve- och energikostnader för luftning. Under de senaste decennierna har vattenbehandlingsprocesserna haft många positiva utvecklingar, vilket har lett till en kvalitetsförbättring av vatten samtidigt som kostnaden för kväveavlägsnande från avloppsvatten har minskat. För närvarande flyttar kvävereningsteknik från konventionell nitrifikations/denitrifikationsprocessen till partiell nitritation/Anammox (PN/A) -processen kallad deammonification. Det verkar som om den största svårigheten är att upprätthålla en stabil ackumulation av nitrit medan man försöker delvis med nitritation av ammonium. Partiell nitritation/Anammox (PN/A) anses vara mer kostnadseffektivt avlägsnande av kväve från avloppsvatten, mer miljövänligt än konventionella nitrifikations-denitrifikationsprocesser på grund av minskat energibehov för luftning och inget behov av en yttre källa av kol.
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Silva, Henrique Joaquim Lopes da Silva e. "Optimization of air micro-bubble bioreactor for the winery wastewater treatment under oxygen-limited conditions." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5308.
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Mestrado em Tecnologias do Ambiente - Tecnologias Ambientais - Instituto Superior de AgronomiaThe energy consumption of wastewater treatment processes had become an important tool parameter for designers and engineers in the wastewater treatment industry, and efforts to improve the energy efficiency of the equipments represent a great challenge. The present study proposes the use of the Air Micro-Bubble Bioreactor (AMBB), with a working volume of 14 dm3 and a hydraulic retention time of 14 days, operating in continuous mode to treat winery wastewater from second racking period, for seven different runs, during 167 days. The organic loads fluctuations, usual in the winemaking industry, and the aeration time rate (ATR), both related to energy costs, were the studied variables. The chemical oxygen demand (COD) was selected as a key parameter to monitor the AMBB performance. The total polyphenol compounds were also followed. The effect of the organic loading rate OLR was assessed by adjusting feed substrate concentration between 0.16-0.44 kg COD m-3 d-1. The ATR varied between 1, 5 and 15 min h-1. Each run was operated until steady state was reached with respect to COD concentration. All runs showed a positive answer for COD removal, having a minimum efficiency of 70%. Also the COD removal efficiency showed to be not dependent on the applied OLR and the decrease in the ATR to 5 min h-1 was accompanied by a nearly three-fold reduction in energy consumption without relevant changing on the final COD removal efficiency (93-96%). However, the total polyphenol compounds removal was highly affected by decreasing the ATR from 15 to 1 min h-1, leading to a decrease in the total polyphenols removal efficiency from 94% to 4%. In the present study, we report for the first time the impact of oxygen-limited conditions in the AMBB performance with emphasis on the efficiency energy use. The polyphenols as a performance indicator, the energy costs of treated wastewater and COD removal efficiency achieved in pilot scale show the technical feasibility of the process, giving a sustainable solution for this important sector of activity.
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Niklasson, Isabell. "Energieffektivisering av aerob reningsprocess : Tillsats av biprodukter i skogsindustriellt avloppsvatten." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-28445.
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In the production of pulp, paper and cardboard, a large amount of water is used daily. The water has to be purified in the internal purifying plant before it reaches the receiving body of water. In the biological purifying stage at the Stora Enso Skoghall mill, an aerated basin is used where the microorganisms, using oxygen, oxidize the organic material to carbon dioxide. The air is pumped from the bottom of the basin and the oxygen can then be transported from the air bubbles to the water through diffusion. The problem with aeration of waste water from the forest industry is that wood residues, such as fatty acids, are making the transport of oxygen in water more difficult. Previous studies show that adding salt improves aeration and the use of energy during the aeration process decreases. In many of the Swedish forest industries the electric power required for the aeration process is responsible for more than 50% of the total use of energy. The aim of this report is to study the aeration of waste water from a forest industry in order to make the aeration in the biological purification stage more energy efficient. The experimental part includes aeration experiments and measurement of surface tension when adding salt in clean and untreated process water. All experiments have been carried out in lab-scale at Karlstad University. The salts used during the study were sodium chloride, lime sludge and also precipitator dust, of which the two latter are by-products of pulping. The project has reached its goal, to compare and measure the speed of aeration when adding different salts to waste water from the forest industry in order to make the purification process more efficient. This study shows that adding by-products may increase the speed of the aeration of waste water from the forest industry and decrease the use of energy during the aerobic treatment process. Adding precipitator dust to the fabrication water increases the speed of the aeration by 60%. The standard oxygen transfer rate (SOTR) decreased from 314tonnes O2/d to 118tonnes O2/d. The energy demand during the aeration process decreased by 100 MWh per day.Vid framställning av massa, papper och kartong används dagligen stora mängder vatten som måste renas vid det interna reningsverket innan det når recipienten. En av industrierna är Stora Enso, Skogshalls bruk. I det biologiska reningessteget vid Skoghalls bruk används en luftad damm där mikroorganismer med hjälp av syre oxiderar det organiska materialet till koldioxid. Luft pumpas in från botten av dammen och syret kan transporteras från luftbubblorna till vattnet genom diffusion. Problemet vid syresättning av skogsindustriellt avloppsvattnet är att vedrester som exempelvis fettsyror följer med avloppsvattnet och försvårar syretransporten. Tidigare studier visar att vid tillsats av salt förbättras syresättningen och att energianvändningen vid luftningsprocessen minskar. De salter som valts i den här undersökningen är natriumklorid samt mesa och elfilteraska. Varav det två sista är biprodukter från massaframställningen. I många av Sveriges skogsindustrier står elen till luftningsprocessen för mer än 50 % av den totala energianvändningen. Det här arbetet syftar till att undersöka syresättningen av ett skogsindustriellt avloppsvatten med avsikt att energieffektivisera luftningen i det biologiska reningssteget. Den experimentella delen omfattar syresättningsförsök samt mätning av ytspänning vid tillsats av salt i både rent vatten och obehandlat processvatten. Samtliga försök har utförts i labbskala vid Karlstads universitet. Det här arbetet har uppnått sitt mål med att jämföra och mäta hastigheten av syresättning vid tillsats av olika salter i skogsindustriellt avloppsvatten med avsikt att energieffektivisera reningsprocessen. Resultatet tyder på att tillsats av biprodukter kan öka hastigheten vid syresättning av skogsindustriellt avloppsvatten och därmed minska energianvändningen vid den aeroba reningsprocessen. Vid tillsats av elfilteraska i processvattnet ökar hastigheten av syresättningen med 60 %. Det verkliga syrebehovet i dammen, SOTR sjönk från 314 ton O2/dygn till 118 ton O2/dygn. Energibehovet vid luftningsprocessen minskade med 100 MWh/dygn.
Books on the topic "Aeration efficiency"
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Larson, Lory. A digital control system for optimal oxygen transfer efficiency: PIER final project report. Los Angeles, CA: California Energy Commission, 2010.
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Shaw, Andrew, and Diego Rosso. Framework for Energy Neutral Treatment for the 21st Century Through Energy Efficient Aeration. IWA Publishing, 2015.
Find full textBook chapters on the topic "Aeration efficiency"
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Hu, Baowei, Chundi Yang, and Wen Cheng. "Study on Efficiency of Aeration Type in Biological Aeration Filter on the Sewage Disposal." In Advances in Water Resources and Hydraulic Engineering, 614–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89465-0_106.
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Verma, Aayushi, Subodh Ranjan, Umesh Ghanekar, and N. K. Tiwari. "Soft Computing Techniques for Predicting Aeration Efficiency of Gabion Stepped Weir." In Lecture Notes on Multidisciplinary Industrial Engineering, 117–22. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73495-4_8.
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Jaiswal, Akash, and Arun Goel. "Evaluation of Aeration Efficiency of Triangular Weirs by Using Gaussian Process and M5P Approaches." In Advanced Engineering Optimization Through Intelligent Techniques, 749–56. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8196-6_66.
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Sangeeta, Subodh Ranjan, and N. K. Tiwari. "Aeration Efficiency Evaluation of Modified Small Parshall Flume Using M5P and Adaptive Neuro-Fuzzy Inference System." In Lecture Notes in Civil Engineering, 243–52. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-6717-5_24.
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Bellandi, G., C. Caretti, S. Caffaz, I. Nopens, and R. Gori. "Multi-point Monitoring of Nitrous Oxide Emissions and Aeration Efficiency in a Full-Scale Conventional Activated Sludge Tank." In Lecture Notes in Civil Engineering, 398–403. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-58421-8_63.
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"Evaluating Aeration System Efficiency." In The Mechanics and Physics of Modern Grain Aeration Management, 585–608. CRC Press, 2001. http://dx.doi.org/10.1201/9781420040333-18.
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Navarro, Shlomo, and Ronald Noyes. "Evaluating Aeration System Efficiency." In The Mechanics and Physics of Modern Grain Aeration Management. CRC Press, 2001. http://dx.doi.org/10.1201/9781420040333.ch10.
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Thomas, V. K., B. Chambers, and W. Dunn. "OPTIMISATION OF AERATION EFFICIENCY: A DESIGN PROCEDURE FOR SECONDARY TREATMENT USING A HYBRID AERATION SYSTEM." In Water Pollution Research and Control Brighton, 1403–19. Elsevier, 1988. http://dx.doi.org/10.1016/b978-1-4832-8439-2.50135-8.
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Bunea, Florentina, and Gabriel Dan Ciocan. "Experimental Study of Standard Aeration Efficiency in a Bubble Column." In Desalination and Water Treatment. InTech, 2018. http://dx.doi.org/10.5772/intechopen.76696.
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"Improving the efficiency of bubble plumes for artificial aeration, mixing, and destratification." In Frontiers of Science and Technology, 48–60. De Gruyter, 2017. http://dx.doi.org/10.1515/9783110537680-004.
Full textConference papers on the topic "Aeration efficiency"
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Amano, R. S., Ammar Alkhalidi, Patrick Bryar, and Wayel Alwayel. "Water Aeration in Wastewater Treatment." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71524.
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The primary objective of this paper is to examine ways to increase the efficiency of water aeration process. This objective was completed through the use of a propeller and fan blade designs. Both Standard oxygen transfer efficiency (SOTE) and power reclamation were analyzed. Results of SOTE analysis indicated a decrease in efficiency, when compared to the standard model air diffuser. While the propeller design was able to successfully breakup the forming bubble column, the system reduced the circulatory currents that create mixing within the experimental tank. Results indicate a small SOTE drop, throughout the system. Power reclamation was able to yield, at a peak depth of 25cm (10 in) below the top water surface, 0.8W, with input energy of approximately 45 W resulting in reclamation of 1.8% of the power put into the system. This data was retrieved at a volumetric flow rate of 9.4 × 10−4 m3/s (2 CFM) with a pressure of 55kPa (8psi).
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Vaideliene, Adele. "Mathematical Modeling of Aeration Process in the Air-Water Interface." In 2020 7th International Conference on Energy Efficiency and Agricultural Engineering (EE&AE). IEEE, 2020. http://dx.doi.org/10.1109/eeae49144.2020.9278993.
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Gullapalli, Sravani, Paul Michael, Jennifer Kensler, Mercy Cheekolu, Robert Ian Taylor, and Enrique Lizarraga-Garcia. "An Investigation of Hydraulic Fluid Composition and Aeration in an Axial Piston Pump." In ASME/BATH 2017 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fpmc2017-4259.
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Manufacturers of fluid power equipment have decreased the size of hydraulic fluid reservoirs in response to economic, environmental and performance requirements. Residence times as brief as 30 seconds in mobile equipment are not unusual. Shorter fluid residence times dictate use of hydraulic fluids with improved air release characteristics. In this investigation, hydraulic fluids of the same ISO viscosity grade but varying base oil and additive composition were evaluated in a dynamometer fitted with a reservoir that incorporated an aerator at the inlet, and a mass flow meter at the outlet. The effects of aeration on piston pump efficiency and air borne noise generation were evaluated. Fluids of the same ISO viscosity grade exhibited significantly different air release rates and as a result sustained different volume fractions of entrained air. Hydraulic oils that entrained a greater volume of air demonstrated lower volumetric efficiencies and higher sound levels. Aerated fluids of the identical viscosity grade differed in volumetric efficiency by as much as 8% and perceived sound level by as much as 50%. Models for the effect of aeration on pump performance are presented.
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Ippoliti, Laurent, Johan Steimes, and Patrick Hendrick. "Investigation on an Oil Aeration Measurement Technique for the Study of Pump Performance in an Aircraft Engine Lubrication System." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43117.
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Previous studies on feed pump performance conducted on the ULB-ATM lubrication system test bench showed the dependence of cavitation and volumetric efficiency with inlet pressure, rotational speed and aeration. This paper presents a technique of aeration measurement applied on the test bench. After a description of the device and a theoretical review of the aeration, the paper shows that the method has been tested with success. The paper illustrates it with a series of tests showing the level of aeration obtained in different operating conditions and a comparison with a pump characteristic measured on the bench.
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Liu, Sibo. "Design of high efficiency and energy saving aeration device for aquaculture." In 11TH ASIAN CONFERENCE ON CHEMICAL SENSORS: (ACCS2015). Author(s), 2017. http://dx.doi.org/10.1063/1.4977278.
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Al Ba'ba'a, Hasan B., Michael A. Prada, Christopher D. Olson, Ammar A. T. Alkhalidi, Ryoichi S. Amano, and Jin Li. "An Experimental Study of Reducing Back Pressure of Fine Air Diffuser Used in Wastewater Plants." In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21203.
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Aeration is the process at which air is added to water, an essential stage in wastewater treatment plants, since most of organic compounds are being treated through such an aeration process. This process also helps aerobic bacteria to survive from oxygenation to proliferate and digest organic materials. However, aeration consumes around 60% of the total cost of remediation. Therefore, any improvement in aeration efficiency (AE) will save a considerable amount of energy consumption. One way of reducing the power required is to decrease the back pressure of the air diffuser itself. In this study, a new material for manufacturing of fine air diffuser is presented. Polypropylene (PP) membrane, which is the new material chosen, shows lower back pressure values in comparison with Silver Series 2 (SS2) membrane at relatively low flow rates. The main reason behind choosing Polypropylene (PP) is that it has lower material resistance than SS2 with maintaining the capability of operation at the same pressure ranges in the aeration process. Despite the fact that SS2 has better oxygen transfer efficiency (OTE), PP membranes have significantly lower back pressure at relatively low flow rates which resulted in higher AE. In addition, contact angle measurements were done for PP and compared with previous measurements for the contact angle of SS2.
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Changzi Guo, Dan Wang, Fei Cheng, and Xuemei Chen. "Study on nitrogen removal efficiency of different aeration modes in oxidation ditch." In 2011 International Conference on Multimedia Technology (ICMT). IEEE, 2011. http://dx.doi.org/10.1109/icmt.2011.6002972.
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Albrektienė, Ramunė, and Mindaugas Rimeika. "Efficiency of Removal of Iron, Manganese, Ammonium and Organic Matter from Groundwater." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.067.
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The acceptable concentrations in groundwater are usually in excess of iron, ammonium and manganese. These compounds are inefficiently removed by means of ordinary technologies of ammonium ions, iron and manganese compounds removal from groundwater (water aeration and filtration through granular filter fillings) where groundwater contains high concentrations of organic compounds. Increased concentrations of organic compounds in groundwater occur in well fields where exploited aquifers have contact with surface water wells and are supplemented with water from open water bodies. Such well field is located in the town of Nida (Lithuania). The norms permitted by Council directive 98/83/EC on the quality of water intended for human consumption are exceeded by iron, ammonium, manganese and organic compounds in this well field. The present study examines the efficiency of drinking water treatment technology of three-stage filtration with aeration and insertion of coagulant (polyaluminum chloride) where ammonium ions, iron, manganese and organic compounds are removed from groundwater in an integral manner. Three fillings were used for filtration: quartz sand, zeolite and quartz sand with oxidizing bacteria. The drinking water treatment technology examined removes ammonium ions, iron, manganese and organic compounds from groundwater in an integral manner until the requirements of the norms of directive 98/83/EC are achieved.
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Amano, R. S., Ammar Alkhalidi, and Patrick Bryar. "Design of a Deflector for Water Aeration in Wastewater Treatment." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86943.
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The aeration phase within wastewater treatment is the most power consuming step required in the treatment of waste water. After the energy crisis in 1970s increasing attention has been paid for this step to reduce the energy cost [1]. Higher standard oxygen transfer efficiency (SOTE) reduces the amount of air required to aerate wastewater which reduce the air blower power consumption. In this study SOTE was investigated for the case of adding a bubble deflector, i.e. an external geometry that directs the bubbles toward the less oxygenated water, which improves the efficiency and eliminates the effect of dead zones in a rectangular water tank.
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Miletta, Bryan A., R. S. Amano, Ammar A. T. Alkhalidi, and Jin Li. "Study of Air Bubble Formation for Wastewater Treatment." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-47065.
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Aeration, a unit process in which air and water are brought into intimate contact, is an extremely important step in the process of wastewater treatment. The two most common systems of aeration are subsurface and mechanical. A mechanical system agitates the wastewater by various means (e.g. paddles, blades, or propellers) to introduce air from the atmosphere. Subsurface aeration is the release of air, in the form of bubbles, within the tank of wastewater to supply the microorganisms with the required amount of oxygen they need to metabolize and break down the organic material suspended in the wastewater. The bubbles of Air are released from the bottom of the wastewater tank through diffusers. These diffusers have a surface membrane, usually made of punched rubber, to create the fine bubbles with high oxygen transfer efficiency from supplied air to the diffusers. Since the energy crisis in the early 1970’s, there has been increased interest in these systems due to its high oxygen transfer efficiency. This paper covers experimentation of different air diffuser membranes, varying in material, used in the aeration process of wastewater treatment. Rubber, EPDM rubber (ethylene-propylene-diene Monomer) and PTFE Polytetrafluoroethylene membranes coated membranes were tested. Experimental results showed that the rubber membrane produced the smallest bubble size against expectation. This could be a result of the coating being on the top surface only and the bubble starts from inside the punch.