Experimental Surface Aeration in the
Chicago River System
J. A. ROEBER, Manager, Waste Treatment R&D
R. J. NOGAJ, Sanitary Engineer, R&D
E. J. CIABATTARI, Director of Engineering
Yeomans Brothers Company
Chicago, Illinois
E. HURWITZ, Consultant
Pollution Control Laboratories, Inc.
Chicago, Illinois
It has been demonstrated that artificial aeration is a feasible method for raising the dissolved oxygen content in oxygen deficient streams. As far back as
1923, the Metropolitan Sanitary District of Greater Chicago studied the possibility
of adding dissolved oxygen to a stream by aerating the water of the main channel
in the District's lock at Lockport (1). Air diffusion through porous media was
used to increase the DO.
Later (1943) air diffusion through porous media was used to raise the DO in
the Flambeau River at Park Falls (2). In 1959, a report published jointly by the
Committee on Water Pollution, State of Wisconsin, and the Sulfite Pulp Manufacturer's Research League, Wisconsin, discussed several applications of vented
turbine aeration in Wisconsin rivers (3).
More recently, the Metropolitan Sanitary District of Greater Chicago in cooperation with Yeomans Brothers Company undertook a study of river aeration by
use of mechanical aerators. It is the purpose of this paper to discuss the performance and results of these tests.
Every river has a definite but limited capacity for natural purification. For
streams whose end use is designated for such purposes as hydroelectric power,
commercial shipping, cooling, and waste assimilation, the limiting factor is their
inability to maintain sufficient DO to prevent anaerobic nuisance conditions at all
points downstream from the waste discharge during critical low flow periods. If
artificial aeration can be used to supplement natural reaeration at low dissolved
oxygen points, the capacity of a stream to assimilate wastes can be greatly increased.
If fixed-position aerators are used, the problem of selecting the locations for
the aeration facilities that will entirely prevent anaerobic conditions in a waterway is very difficult. The variables that affect stream conditions such as flow
rate, the character of the polluting substances, the microorganisms variety and
population, temperature, sludge deposits, and other factors are constantly changing. These changes may shirt the DO sag-curve. Since oxygen absorption is
proportional to the oxygen deficit, such shifts could seriously reduce the transfer
efficiency of the aeration mechanism and the rate of natural reaeration. These
and other considerations indicate that a movable surface aerator would be better
adapted for river aeration purposes.
Under contract with the Metropolitan Sanitary District of Greater Chicago, an
experimental aerator was built and operated for a period of 120 twenty-four-hr
days during 1962 and 1963 in the District waterways.    The experiment was not
- 439 -