Title: Rheology and oxygen transfer in CFD models for wastewater

Authors: Valerie Guimet, Thomas Honore, Jean-Marc Audic, Zdravka Do-Quang

Addresses: SUEZ ENVIRONMENT – CIRSEE, 38 rue du President Wilson, 78 230 LE PECQ, France. ' EAU & FORCE, 300 rue Paul Vaillant Couturier, 92007 NANTERRE, France. ' SUEZ ENVIRONMENT – CIRSEE, 38 rue du President Wilson, 78 230 LE PECQ, France. ' SUEZ ENVIRONMENT – CIRSEE, 38 rue du President Wilson, 78 230 LE PECQ, France

Abstract: This paper is a contribution to Computational Fluid Dynamics (CFD) modelling enhancement for the wastewater industry, in particular in the sludge behaviour or rheology and oxygen transfer appearing in clarifiers and aerators. Rheology studies the flow property as a function of external constraints, e.g., concentration and shear stress. Following recent studies (Baudu et al., 1999) in the characterisation of activated sludge, a Casson model is used for the floc and water mixing viscosity, in the liquid-solid separation process. Furthermore, a mass transfer/transport equation is added to the previous system to reproduce the phenomena encountered in the aeration process. CFD results are in good agreement with on-site measurements. Heterogeneity zones can be tracked, easily helping plant operation assessment and optimisation through more realistic CFD.

Keywords: wastewater treatment; rheology; oxygen transfer; computational fluid dynamics; CFD; sludge behaviour; modelling; liquid-solid separation; aeration.

DOI: 10.1504/PCFD.2007.013014

Progress in Computational Fluid Dynamics, An International Journal, 2007 Vol.7 No.2/3/4, pp.219 - 229

Published online: 03 Apr 2007 *

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