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Open AccessArticle

Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

1
College of Energy and Electrical Engineering, Hohai University, Nanjing 210098, China
2
College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
3
School of Hydropower and Information Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
4
Technological Institute of Merida, Technological Avenue, Merida 97118, Mexico
*
Author to whom correspondence should be addressed.
Water 2019, 11(12), 2506; https://doi.org/10.3390/w11122506
Received: 15 October 2019 / Revised: 17 November 2019 / Accepted: 25 November 2019 / Published: 27 November 2019
The oxidation ditch (OD) plays an important role in wastewater treatment plants. With increasing demand and production costs, the energy consumption and sludge deposition occurring in the OD must be diminished to enhance its development. In this paper, a two-phase computational fluid dynamics (CFD) model of water and activated sludge examined the flow field characteristics of an OD, consisting of two side-by-side propellers. The system was studied under five configurations, where the spacing between the propellers was set equal to −0.2, −0.1, 0, 0.1, 0.2 times the length of the OD. The viscosity and settling rate of activated sludge was imported in the numerical simulation through a user defined function (UDF). The optimal scheme of the propeller’s power consumption, velocity distribution, and sludge concentration distribution was obtained. The result shows that sludge concentrations are linked with dead zone velocity but not necessarily with low velocities. Experiments confirmed the validity of the velocity flow field simulated by the two-phase CFD model. Overall, these findings form the basis for the propellers distribution optimization and allow a deeper insight into the flow field of OD systems.
Keywords: oxidation ditch; two-phase CFD; flow field; sludge concentration; submerged propeller oxidation ditch; two-phase CFD; flow field; sludge concentration; submerged propeller
MDPI and ACS Style

Zhang, Y.; Li, C.; Xu, Y.; Tang, Q.; Zheng, Y.; Liu, H.; Fernandez-Rodriguez, E. Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model. Water 2019, 11, 2506.

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