APPLICATION OF A UNIQUE AERATION DEVICE
TO A TEXTILE WASTEWATER
Ken Norcross, Project Engineer
Gerry Shell, President
Gerry Shell Environmental Engineers
Brentwood, Tennessee 37027
INTRODUCTION
One fundamental phenomenon observed in the application of surface aeration is that
the oxygen transfer efficiency increases with increasing power input per unit area or volume. This effect is felt to be the result of synergistic flow patterns and secondary
aeration occurring at the basin walls due to bubble entrainment.    Since motor speed
aerators are normally applied to large lagoons where the power input per unit are is
very low, the oxygen transfer rate observed in small test facilities is not representative.
Any aeration device applied to large surface areas such as lagoons should preferably be
more efficient as the surface area increases per unit of power input. A surface aerator
that would achieve an increase of oxygen transfer efficiency with increasing surface
area would indeed be unique. Most of the aeration devices presently available perform
better in more confined conditions.
This paper presents the results of a series of clean water unsteady state and process
water steady state oxygen transfer tests on a new concept of surface aerators that
demonstrate an increase in oxygen transfer efficiency with increasing liquid surface area.
DESCRIPTION OF AERATOR
The significant operational differences between the aerator tested and the conventional motor speed surface aerators available is the angle at which the issue from the
aerator is discharged and the high pumping rates achieved.    The device evaluated,
rather than allowing the discharge to issue upward to achieve air-water contact, deflects
the discharge horizontally in order to maximize the radial momentum. By better utilization of
the kinetic energy of the liquid pumped, oxygen transfer is achieved through induced surface
reaeration in areas remote from the unit. Figure 1 shows a cutaway view of the aerator evaluated. It is a patented device developed by Sydnor Hydrodynamics, Inc., located in Richmond,
Virginia and identified by the trade name Sydco Oxygenator. Figure 2 shows the typical discharge of the aeration device evaluated and a standard motor speed aerator.
Because of the maximizing of horizontal momentum, it was theorized by the developer that oxygen transfer efficiency of the aerator tested would increase with
increasing surface area. In fact, this anticipated effect was observed during the standard
clean water testing. Because the concept of maximizing momentum was new to the
authors and counter to all published data, it was agreed that additional field testing
was needed. The resulting field testing was used to confirm this new concept in aeration.
AERATION THEORY
The basic expression employed in the evaluation of aeration equipment is the mass
transfer expression:
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