Water Science & Technology: Water Supply Vol 1 No 2 pp 123–130 © IWA Publishing 2001
Ozone mass transfer in water treatment: hydrodynamics and mass transfer
modeling of ozone bubble columns
MG El-Din* and DW Smith**
*
Department Civil and Environmental Engineering, University of Alberta,
Edmonton, Alberta, Canada T6G 2M8
**
Department Civil and Environmental Engineering, University of Alberta,
Edmonton, Alberta, Canada T6G 2M8
ABSTRACT
Most of the mathematical models that are employed to model the performance
of bubble columns are based on the assumption that either plug flow or
complete mixing conditions prevail in the liquid phase. Although due to the
liquid-phase axial dispersion, the actual flow pattern in bubble columns
is usually closer to being mixed flow rather than plug flow, but still
not completely mixed flow. Therefore, the back flow cell model (BFCM), that
hypothesises both back flow and exchange flow to characterise the
liquid-phase axial dispersion, is presented as an alternative approach
to describe the hydrodynamics and mass transfer of ozone bubble columns.
BFCM is easy to formulate and solve. It is an accurate and reliable design
model. Transient BFCM consists of NBFCM ordinary-first-order differential
equations in which NBFCM unknowns (Yj) are to be
determined. That set of equations was solved numerically as NBFCM
linear algebraic equations. Steady-state BFCM consists of
3  NBFCM non-linear algebraic equations in which 3 NBFCM unknowns (qG,j, Xj, and
Yj) are to be determined. Those non-linear algebraic equations
were solved numerically using Newton–Raphson technique.
Steady-state BFCM was initially tested using the pilot-scale experimental
data of Zhou. BFCM provided excellent predictions of the dissolved ozone
profiles under different operating conditions for both counter and
co-current flow modes.
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