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MODELS FOR OXYGEN TRANSFER: THEIR THEORETICAL BASIS AND IMPLICATIONS FOR INDUSTRIAL WASTEWATER TREATMENT Michael K. Stenstrom, Assistant Professor School of Engineering and Applied Science University of California Los Angeles, California 90024 INTRODUCTION Most models for oxygen transfer are based upon early work by Lewis and Whitman [ 1 ] who showed that absorption of gases could be expressed as a diffusion process across two stagnant films. For the special case of sparingly soluble gases and liquids, such as oxygen in water, the model reduces to a single film transport process. For a complete mixing oxygen absorption reactor, the Lewis and Whitman model can be written as follows: JT = KLa <CS " C> « r where: K. a ■ apparent mass transfer coefficient (T ) Co = apparent saturation dissolved oxygen concentration (mg/l) C = dissolved oxygen concentration (mg/l) In developing Equation 1 and its common integrated form, several assumptions are generally made, including constant transfer coefficient and saturation coefficient with respect to time. It has been shown by later investigators that neither assumption is valid for all cases, including applications commonly found in wastewater treatment. The true mass transfer coefficient, Kj^ varies with the "age" of the liquidgas interface [2,3]. Also the saturation oxygen concentration is not constant and varies with hydrostatic head and gasphase oxygen pressure. This phenomena was noted experimentally as early as 1935 by Ressner and Ribbius [4], The combined effects of the partially valid assumptions, which were used to develop Equation 1, produce discrepancies between predicted oxygen transfer capability and actual process performance. Nevertheless, Equation 1 is widely used for measuring and predicting oxygen transfer and will be used until a more fundamental model can be universally accepted. The problem of determining and predicting oxygen transfer capability for a wastewater treatment process becomes one of estimating meaningful parameters for Equation 1. Often the parameters for Equation 1 are estimated from clean water nonsteady state testing, and are then applied to field applications through appropriate conversion factors. The objective of this paper is to show the shortcomings of the commonly used model, and how these shortcomings affect process performance. The theoretical problems stem from the steady state assumptions which were used to develop Equation 1. The inability to precisely and accurately estimate parameters is one practical result of model imperfections; scaleup problems from test facilities to commercial installations is another. 679
Object Description
Purdue Identification Number  ETRIWC1978074 
Title  Models for oxygen transfer : their theoretical basis and implications for industrial wastewater treatment 
Author  Stenstrom, Michael K. 
Date of Original  1978 
Conference Title  Proceedings of the 33rd Industrial Waste Conference 
Conference Front Matter (copy and paste)  http://earchives.lib.purdue.edu/u?/engext,27312 
Extent of Original  p. 679686 
Collection Title  Engineering Technical Reports Collection, Purdue University 
Repository  Purdue University LIbraries 
Rights Statement  Digital object copyright Purdue University. All rights reserved. 
Language  eng 
Type (DCMI)  text 
Format  JP2 
Date Digitized  20090622 
Capture Device  Fujitsu fi5650C 
Capture Details  ScandAll 21 
Resolution  300 ppi 
Color Depth  8 bit 
Description
Title  page0679 
Collection Title  Engineering Technical Reports Collection, Purdue University 
Repository  Purdue University Libraries 
Rights Statement  Digital copyright Purdue University. All rights reserved. 
Language  eng 
Type (DCMI)  text 
Format  JP2 
Capture Device  Fujitsu fi5650C 
Capture Details  ScandAll 21 
Transcript 
MODELS FOR OXYGEN TRANSFER: THEIR THEORETICAL BASIS
AND IMPLICATIONS FOR INDUSTRIAL WASTEWATER TREATMENT
Michael K. Stenstrom, Assistant Professor
School of Engineering and Applied Science
University of California
Los Angeles, California 90024
INTRODUCTION
Most models for oxygen transfer are based upon early work by Lewis and Whitman
[ 1 ] who showed that absorption of gases could be expressed as a diffusion process
across two stagnant films. For the special case of sparingly soluble gases and liquids,
such as oxygen in water, the model reduces to a single film transport process. For a
complete mixing oxygen absorption reactor, the Lewis and Whitman model can be
written as follows:
JT = KLa 
Resolution  300 ppi 
Color Depth  8 bit 
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