Computational fluid dynamics simulation of two-phase flow and dissolved oxygen in a wastewater treatment oxidation ditch

Matko, T.; Chew, Y.M. John; Wenk, Jannis; Chang, Jian; Hofman, Jan

doi:10.1016/j.psep.2020.08.017

Cited by 31 publications

(13 citation statements)

References 46 publications

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“…Changes in influent flow and sludge load disturbances can cause dissolved oxygen concentrations to fluctuate. Low dissolved oxygen concentration can cause aerobic bacteria in the aeration basin to react insufficiently, which in turn reduces their activity when microorganisms in the aeration basin are performing biochemical reactions [3][4][5]. The slower rate of aerobic bacteria growth results in longer wastewater treatment times and poorer effluent quality.…”

Section: Short Research Articlementioning

confidence: 99%

Design of Fuzzy Control System for Dissolved Oxygen Concentration in Aeration Tank

2022

JERR

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The effluent quality of the wastewater treatment is significantly influenced by the amount of dissolved oxygen in the wastewater aeration tank. In this paper, we design a fuzzy control system to regulate the concentration of dissolved oxygen in the aeration tank based on the fact that the control process of dissolved oxygen concentration in actual engineering is characterized by nonlinearity, large fluctuation, and severe hysteresis. The dissolved oxygen concentration is real-time controlled by the control system using the dissolved oxygen concentration as the controlled variable and the aeration of the blower as the manipulated variable. The simulation of the fuzzy control system using MATLAB software demonstrates that the response of the control system to the level of dissolved oxygen in the aeration tank is accelerated, and the outcome has strong robustness and good stability. With this design, the aeration tank's energy loss is decreased while the efficacy of the wastewater treatment is maintained.

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Section: Short Research Articlementioning

confidence: 99%

Design of Fuzzy Control System for Dissolved Oxygen Concentration in Aeration Tank

2022

JERR

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“…That results in heterogeneous distribution of the flow velocity in the SAT characterized by an intensive movement along the axial direction and more important radial velocities at the surface aerator region. The interactions of these effects with the swirl motion generated by the rotation of the surface aerator increase turbulence in the SAT and accelerate the exchange of water between the interface layer, which is supersaturated with oxygen, and the shallow layers, leading to a higher oxygen transfer rate and better flow homogenization and dissolved oxygen distribution in the SAT [22].…”

Section: Influence Of Surface Aerator Speedmentioning

confidence: 99%

Numerical Investigation of Hydrodynamic in a Full-Scale Surface Aeration Tank

Bekrentchir¹,

Mahdi²,

Dellal³

et al. 2022

IJHT

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This study presents a computational fluid dynamics (CFD) model of a full-scale surface aeration tank (SAT) equipped with a low speed surface aerator, model Landy-7. The multiple reference frames (MRF) approach coupled with the volume of fluid (VOF) model and k-ε turbulence model is applied to predict the turbulent flow induced by the surface aerator and the free surface motion. Simulations are performed for different rotational speeds and the predicted results in terms of steady-state power consumption are compared with literature data. After validation, the CFD model is used to study in detail the flow behavior in the SAT and then to optimize the submergence depth ratio of the surface aerator. Two different flow cases are observed depending on the aerator rotation speed. For low rotational speeds, the Landy-7 aerator acts as a surface aerator affecting mainly the water near the surface and has little effect on the shallow layers and the air-water interface is identified as the optimal position for the surface aerator. For aerator rotation speeds above 24 rpm, this effect persists longer in the SAT, even for large submersion depth ratios, which means that the Landy-7 aerator acts as an agitator as well as a surface aerator.

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“…To determine K 3 is important, and significant errors in the K 2 estimate are produced when a DO sink in the WSS is not considered. A few studies have investigated the presence of DO sinks, but they only take into account the chemical and biological sinks, disregarding the physical effects of the experimental setup (e.g., Matko et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of dissolved oxygen sinks in water-stirring setups used in reaeration experiments

Ferreira

Luz

Silveira

et al. 2022

Water Science and Technology

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Dissolved oxygen (DO) is an essential parameter of water quality, and the surface reaeration process (K2) is the main source of DO in aquatic ecosystems. On a laboratory scale, reaeration measurements are performed using water-stirring setups (WSSs), but possible physical DO sinks are not considered in the WSSs. This paper aimed to assess the presence of physical DO sinks in WSSs. The experiments were carried out in four WSSs: circular hydraulic channel (CHC); straight hydraulic channel (SHC); turbine-stirred tank (TST); and oscillating grid tank (OGT). The physical DO sink was estimated by inserting a first-order term (K3, day−1) in the classic equation of DO balance. All WSSs presented physical DO sinks during the reaeration experiments: SHC (mean K3 = 4.58 day−1) > TST (mean K3 = 1.30 day−1) > CHC (mean K3 = 1.12 day−1) > OGT (mean K3 = 0.13 day−1). Physical DO sinks were originated from low-pressure zones located in WSSs, which was confirmed by the negative correlation (r = −0.78) between K3 and the static pressure in the suction pipeline of the SHC. This study presented additional information about identifying, and quantifying, physical DO sinks in WSSs, which are essential to produce a correct estimation of the K2.

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Computational fluid dynamics simulation of two-phase flow and dissolved oxygen in a wastewater treatment oxidation ditch

Cited by 31 publications

References 46 publications

Design of Fuzzy Control System for Dissolved Oxygen Concentration in Aeration Tank

Design of Fuzzy Control System for Dissolved Oxygen Concentration in Aeration Tank

Numerical Investigation of Hydrodynamic in a Full-Scale Surface Aeration Tank

Evaluation of dissolved oxygen sinks in water-stirring setups used in reaeration experiments

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