Impact of bubble and free surface oxygen transfer on diffused aeration systems

Connie D. DeMoyer, Erica L. Schierholz, John S Gulliver, Steven C. Wilhelms

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


The primary location of oxygen transfer in a diffused aeration system is examined by separately determining the surface air-water and bubble-water mass transfer coefficients. The mass transfer model developed to determine the mass transfer coefficients advances the McWhirter and Hutter (A.I.Ch.E. J. 35(9) (1989) 1527) model by tracking oxygen and nitrogen transfer into and out of the bubbles as they rise to the water surface. The resulting vertical profiles of the liquid-phase equilibrium concentration inside the bubble and the gas-phase oxygen composition give insight into how the bubble-water concentration gradient changes over depth. The surface mass transfer coefficient, kLsas, is 59-85% of the bubble mass transfer coefficient, kLab, and the driving concentration difference is smaller for surface transfer. Surface transfer and bubble transfer both contribute significantly to oxygen transfer; however, bubble transfer is the primary mode of oxygen transfer for this system at the air flow rates used. Further experiments demonstrate that most of the surface transfer occurs above the bubble plume.

Original languageEnglish (US)
Pages (from-to)1890-1904
Number of pages15
JournalWater Research
Issue number8
StatePublished - Apr 2003


  • Aerator
  • Bubble transfer
  • Lake aeration
  • Submerged diffuser
  • Surface transfer
  • Transfer coefficient


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