Investigation of the
Effects of Channel Geometry and Surface
Velocity on the Reaeration Rate Coefficient
W. P. ISAACS, Associate Professor
Sanitary Engineering Department
New Mexico State University
University Park, New Mexico
J. A. MAAG, Sanitary Engineer
Shell Oil Company
Bakersfield, California
INTRODUCTION
The discharge of municipal and industrial wastes into rivers and streams presents a problem of major importance in the field of water pollution control. As
industry and population continue to grow, so does the problem of ultimate disposal
of their wastes.
The bio-oxidation of organic waste occurring in a stream receiving organic
wastes utilizes the dissolved oxygen in the water. The primary replacement of
dissolved oxygen in a natural stream occurs through atmospheric reaeration, which
is the replaceme nt of oxygen to the body of a liquid through the water surface exposed to the  atmosphere.    Atmospheric reaeration is defined by the equation
42- = - ICcjD (1)
were D is the DO deficit (the difference between the saturated oxygen level and
the amount of oxygen present in the liquid at any time, t) and K2 is the coefficient of reaeration. This relationship shows that the time rate of change of oxygen deficit is directly proportional to the deficit.
The definition of this proportionality constant, in terms of measurable stream
parameters, therefore, must be accurately forumlated before the pollution control
engineer can determine the safe organic loading of a stream.
REVIEW OF PREVIOUS INVESTIGATIONS
In February 1967, Isaacs (1) made an extensive review of the historical development of the reaeration rate constant, K2. Hence, only a brief review of the
development of the theoretical and practical reaeration rate concepts will be
presented in this report.
Adeney and Becker (2), in 1919, showed that the change in oxygen deficit in
water was a first order kinetic reaction involving the reaeration rate constant.
- 619 -