Modélisation de l' Hydrodynamique et du transfert d'oxygène dans les chenaux d'aération

par Yannick Fayolle

Thèse de doctorat en Epuration des eaux usées

Sous la direction de Alain Héduit.

Soutenue en 2006

à Toulouse, INSA .

  • Titre traduit

    Flow and oxygen modelling in aeration tanks


  • Pas de résumé disponible.


  • Résumé

    The objective of this work was to develop a tool in order to analyse and to model hydrodynamics and oxygen mass transfer in aeration tanks equipped with EDPM fine bubble membrane diffusers and slow speed mixers. This tool will be used to simulate and interpret the impact of design and operating parameters on oxygen transfer in aeration tanks. Measurement methods were firstly developed to determine in situ local parameters that govern hydrodynamics and oxygen mass transfer (horizontal liquid velocity, gas hold-up, bubble size), in clean water on real sites. The bubble size slightly decreases with the horizontal liquid velocity (from 4. 6 to 4. 4 mm for an increase in horizontal liquid velocity from 0 to 0. 42 m. S-1). The obtained enhancement of the oxygen transfer coefficient (+29%) with the horizontal liquid velocity is mainly due to the increase in the global gas hold-up, by neutralization of the spiral flows. The second objective was to develop a computerised tool in order to simulate gas/liquid flows in aeration tanks. This tool, validated on a pilot unit (1 m3) and on a real site (1493 m3), can precisely reproduce the oxygen transfer. Finally, this numerical tool was used to analyze the local oxygen transfer phenomena. The evolution of the instantaneous saturation oxygen concentration CL* and its influence on the determination of the oxygen transfer coefficient were highlighted. An adaptation of the method to determine the oxygen transfer coefficient taking into account this evolution was proposed. The impact of the arrangement of diffuser grids, of the surface air flow rate (air flow divided by the total area covered by the diffuser grids) and of the horizontal liquid velocity on oxygen transfer was globally and locally analyzed.

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La version de soutenance existe sous forme papier

Informations

  • Détails : 1 vol. (265 p.)
  • Notes : Publication autorisée par le jury
  • Annexes : Bibliogr. p. [249-258].

Où se trouve cette thèse ?

  • Bibliothèque : Institut national des sciences appliquées. Bibliothèque centrale.
  • Disponible pour le PEB
  • Cote : 2006/856/FAY

Cette version existe également sous forme de microfiche :

  • Bibliothèque : Université Pierre et Marie Curie. Bibliothèque Universitaire Pierre et Marie Curie. Section Sciences de la Terre Recherche - cartothèque - CADIST.
  • Disponible pour le PEB
  • Cote : 06 ISAT 0035
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