Evaluation of oxygen transfer parameters of fine-bubble aeration system in plug flow aeration tank of wastewater treatment plant

Zhou, Xin; Wu, Yuanyuan; Shi, Hanchang; Song, Yanqing

doi:10.1016/s1001-0742(12)60062-x

Cited by 22 publications

(14 citation statements)

References 10 publications

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“…Most investigations in bubble columns have been performed for aqueous systems. Based on a large number of studies on oxygen transfer in clean water, the American Society of Civil Engineers (ASCE) standard was established to measure the oxygenation capacity of aeration devices in clean water [6]. The impacts of physical variables such as temperature, reactor geometry, pressure, surface tension, mixing, and viscosity on oxygen transfer in clean water are well documented and understood.…”

Section: Introductionmentioning

confidence: 99%

Impact of Cellulose and Surfactants on Mass Transfer of Bubble Columns

et al. 2019

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The effects of cellulose, surfactants, and their combination on the hydrodynamic behavior and the liquid‐side mass transfer coefficient of a bubble column were evaluated. For that purpose, different aqueous solutions containing surfactants (sodium dodecyl sulfate) and cellulose (microcrystalline cellulose, MCC) were investigated. The interfacial areas were calculated from the bubble diameters, the bubble frequencies, and the terminal bubble rising velocities. The liquid‐side mass transfer coefficients were determined from the volumetric mass transfer coefficients measured by the dynamic method. In the concentration range under test, the experimental results proved that the addition of MCC to the studied liquid phases did not affect the mass transfer coefficient.

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Section: Introductionmentioning

confidence: 99%

Impact of Cellulose and Surfactants on Mass Transfer of Bubble Columns

et al. 2019

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“…The parameter estimation, based on an assumed power function (Zhou et al, 2012), has determined that it is a power function of Q 0:82 a ; therefore K L a/Q 0:82 a ¼ 0.4515(1/C Ã ' ), as shown in the graph. As will be seen later, using the same power exponent for tanks other than the baseline is only an approximation, as R 2 ¼ 0.9859 is not as good as when the baseline values are used.…”

Section: Example Calculationmentioning

confidence: 98%

“…The exponent is 0.82. The value obtained from the slope is 44.35 3 10 À3 (1/min) for all the gas rates normalized to give the best fit, bearing in mind that K L a 0 is assumed to be related to the gas flowrate by a power curve with an exponent value (Stenstrom et al, 2006;Zhou et al, 2012). The slope of the curve is defined as the standard specific baseline.…”

Section: Example Calculationmentioning

confidence: 99%

Development of a Model to Determine the Baseline Mass Transfer Coefficient in Bioreactors (Aeration Tanks)

Lee¹

2018

Water Environment Research

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Over 60 percent of all wastewater treatmentplants in the developed countries use the activated sludgeprocess as secondary treatment system. About 50 to 85 percentof the total energy consumed in a biological wastewatertreatment plant is in aeration. The activated sludge process, themost common process, is performed in large aeration basins toprovide air for microorganisms, through biodegradation, toremove nutrients and pollutants. Very often excess factor ofsafety used in design for the air supply to meet sustained peakorganic loading and to avoid endogenous situations may lead tounsatisfactory treatment performance and even plant failure.The current improper sizing of the aeration system is primarilydue to the inability to estimate the mass transfer coefficient(KLa) correctly for different tank depths, among other things,leading to improper blower design and to inappropriateoperation. In general, the efficiency of porous fine-bubblediffuser systems varies from 10 to 30 percent or more, dependingon tank depth. The term (KLa) has been used in the ASCEstandard (ASCE/EWRI 2-06) to define the apparent volumetricmass transfer coefficient in a non-steady clean water test in anaeration tank. This parameter is a function of tank depth, due tothe degree of oxygen gas depletion for each depth. The objectiveof this paper is to introduce a baseline oxygen mass transfercoefficient (KLa0), a hypothetical parameter defined as theoxygen transfer rate coefficient at zero depth, and to developnew models relating KLa to the baseline KLa0 as a function oftemperature, system characteristics (e.g., the gas flow rate, thediffuser depth Zd), and the oxygen solubility (Cs). Results of thisstudy on data extracted from the literature indicate that auniform value of KLa0 that is independent of tank depth can beobtained experimentally. Using the baseline, a family of ratingcurves for KLa20 (the standardized KLa at 20 8C) can thus beconstructed for various gas flow rates applied to various tankdepths. The new model relating KLa to the baseline KLa0 is anexponential function, and (KLa0)T is found to be inverselyproportional to the oxygen solubility (Cs)T in water to a highdegree of correlation. Using a pre-determined baseline KLa0, thenew model predicts oxygen transfer coefficients KLa20 for anytank depths to within 1~3% error compared to observedmeasurements and similarly for the standard oxygen transferefficiency (SOTE%). Therefore, the discovery of a standardbaseline (KLa0)20 determined from shop tests is important forpredicting the KLa20 value for any other aeration tank depth andgas flowrate, and this finding can be utilized in the developmentof energy optimization strategies for wastewater treatmentplants. This work may also improve the accuracy of aerationmodels used for aeration system evaluations. Water Environ.Res., 90 (2018).

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“…Thus, this method is the easiest to recommend because it frees users from dealing with aeration tank power levels, does not rely on constant oxygen uptake, and avoids hazardous chemical use. Moreover, the off-gas method is a low-cost WWTP/WRRF monitoring option that provides results with low variability at approximately 10% (Capela et al, 2004;Mueller and Boyle, 1988;Zhou et al, 2013). The Obscure a-Factor.…”

Section: Parameter Estimation For Oxygen Transfer Efficiencymentioning

confidence: 99%

A Critical Review of the Factors Affecting Modeling Oxygen Transfer by Fine‐Pore Diffusers in Activated Sludge

Baquero-Rodríguez

Lara-Borrero

Nolasco

et al. 2018

Water Environment Research

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In this review, the factors affecting the transfer of oxygen in activated sludge processes using fine-pore diffusers for water resource recovery are critically discussed. In water resource recovery facilities, the energy required for aeration constitutes 50% to 80% of the total energy consumed by the plant. This critical review highlights the use of fine-pore diffuser aeration and emphasizes the significance of accounting for the following factors: diffuser aging and fouling, diffuser layout, diffuser type, selector benefits, local environmental conditions (temperature and atmospheric pressure), influent wastewater variability, dissolved oxygen control systems, and airflow rates. In our review, we were unable to find mathematical models that could be used to develop dynamic α-factor predictions and diffuser fouling predictions. Although the development of a model that considers all the factors that affect oxygen transfer efficiency (OTE) in activated sludge systems would be extremely valuable, the creation of such a model is outside the scope of this review.

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Evaluation of oxygen transfer parameters of fine-bubble aeration system in plug flow aeration tank of wastewater treatment plant

Cited by 22 publications

References 10 publications

Impact of Cellulose and Surfactants on Mass Transfer of Bubble Columns

Impact of Cellulose and Surfactants on Mass Transfer of Bubble Columns

Development of a Model to Determine the Baseline Mass Transfer Coefficient in Bioreactors (Aeration Tanks)

A Critical Review of the Factors Affecting Modeling Oxygen Transfer by Fine‐Pore Diffusers in Activated Sludge

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