Development of Mathematical Model for Overall Oxygen Transfer Coefficient of an Aerator and Comparison with CFD Modeling

The value of overall oxygen transfer Coefficient (KLa), which is the best measure of oxygen transfer in water through aeration, is obtained by a simple approach, which sufficiently explains the utility of the method to eliminate the discrepancies due to inaccurate assumption of saturation dissolved oxygen concentration. The rate of oxygen transfer depends on number of factors like intensity of turbulence, which in turns depends on the speed of rotation, size, and number of blades, diameter and immersion depth of the rotor, and size and shape of aeration tank, as well as on physical, chemical, and biological characteristic of water. An attempt is made in this paper to correlate the overall oxygen transfer Coefficient (KLa), as an independent parameter with other influencing parameters mentioned above. It has been estimated that the simulation equation developed predicts the values of KLa and power with an average standard error of estimation of 0.0164 and 7.66 respectively and with R2 values of 0.979 and 0.989 respectively, when compared with experimentally determined values. The comparison of this model is done with the model generated using Computational fluid dynamics (CFD) and both the models were found to be in good agreement with each other.

Authors:

• Shashank.B. Thakre
• L.B. Bhuyar
• Samir.J. Deshmukh

Keywords:

• CFD Model
• Overall oxygen transfer coefficient
• Power
• Mathematical Model
• Validation.

References:

[1] Metcalf and Eddy Inc. "Waste water Engineering; Treatment disposal
and reuse". Tata McGraw Hill. New Delhi, India. American Public
Health Association. 2001
[2] Rao, A. R.. "Predication of reaeration rate in square, stirres tanks." J.
Environ. Engg. 133(4), 411 - 418. 1999
[3] Moulick, S. Mal, B.C. Bandyopadhyay, S. "Design characteristics of
single hub paddle aerator." J. Environ. Engg. 131(8), 1147-1154. 2005.
[4] Cancino, B. "Design of high efficiency surface aerators part2. Rating of
surface aerator rotors". Aquacultural Eng. Elsevier., 31, 99-115. 2004.
[5] Rajput ,R.K (2002). "Fluid Mechanics and Hydraulic Machines". S.
Chand & [6]Company LTD, New Delhi. ISBN: 81 - 219 - 1666 - 6.
[6] Gancarski, P. (2007). "CFD modeling of an oxidation ditch." wat. Res.
Tech. Cranfield University, France.