26    EVALUATION OF OXYGEN TRANSFER PARAMETERS FOR
INDUSTRIAL WASTEWATERS
Robert C. Backman, Graduate Student
James C. O'Shaughnessy, Associate Professor
Department of Civil Engineering
Northeastern University
Boston, Massachusetts 02115
Fredrick J. Siino, Technical Process Engineer
Mass Transfer Systems, Inc.
Fall River, Massachusetts 02721
INTRODUCTION
The use of aeration devices to transfer oxygen and completely mix activated sludge is an energy
intensive process. Due to the never ending increase in electricity costs, the need for cost effective
design of aeration equipment is a necessity. Most aeration system performance evaluations have been
reported utilizing clean water oxygenation tests. The purpose of this study is to evaluate dirty oxygen
transfer parameters for both jet and fine bubble dome aeration systems for a variety of industrial
wastewaters.
Specifically, clean and dirty water non-steady state oxygenation tests were conducted using the fore
mentioned aeration systems in tanks with similar geometric configurations. Specific objectives of this
study were:
1) Determine alpha and beta factors for the following wastewaters:
a) Dairy
b) Brewery
c) Textile
d) Soft drink
e) Municipal
0 Clean water with surfactants.
2) Evaluation of oxygen transfer parameters for the previous listed wastewaters using two
different aeration systems under similar operating conditions (same clean water KLa
values) and relate impurity levels to alpha.
3) From this study provide insight into the next appropriate step to further define the
effectiveness of oxygen transfer for both jet and fine bubble dome aeration systems for
industrial wastewaters.
BACKGROUND
The oxygen transfer mechanism in wastewater treatment is usually described by the two-film theory
of mass transfer of oxygen from the gas phase to the liquid phase. The basic equation which describes
the oxygen transfer process is:
- = KLa(C - C) (1)
dt
where,
(dc)/(dt) = rate of oxygen transfer
KLa = overall oxygen transfer coefficient
C* = dissolved oxygen saturation concentration
C = dissolved oxygen concentration at time, t
234