WHO IS USING OXYGEN
AERATION?

Below is a partial listing of full-scale mu-
nicipal wastewater treatment plants cur-
rently using or planning to use oxygen

aeration

Size

(Million

Location Gallons/Day)
Detroit, Michigan 300
Middlesex County, N.J. 120
East Bay MUD, Calif. 120
Louisville, Ky. 105
Miami, Fla. SS
Hollywood, Fla. 36
Danville, Va 24
Euclid, Ohio 22
Newtown Creek, N.Y.C. 20
Decatur, Ill. 18
Fayetteville, N.C. 16
Salem, Oregon 16
New Rochelle, N.Y. 14
Fairfax County, Va. 12
Jacksonville, Fla. 10
Speedway, Ind. 10
Morganton, N.C. 8
Deer Park, Texas 6
Baltimore, Md. 3

WHERE CAN | GET MORE INFORMATION?

Contact your consulting engineering firm
or write to:

Technology Transfer
Environmental Protection Agency
Washington, D.C. 20460

+ GPO ; 1973 © - 496-896


A new wastewater treatment process has
been developed which utilizes oxygen-en
riched air or pure gen. This proc
termed oxygen aeration or, more simply,
oxygenation. The potential of oxygen aer-
ation has resulted in an extremely rapid
acceptance by consulting engineers, mu-
nicipalities, and industries. The first full-
scale application of the oxygen aeration
process to the treatment of municipal
wastewater occurred in 1969 under a dem-
onstration contract from the U.S. Environ-
mental Protection Agency’s forerunner,
the Federal Water Pollution Control Ad-
ministration. In this demonstration pro-
ject, a total of 1.25 million gallons per

lay of sewage was treated. Today, jus
three years later, over 35 full-scale muni
cipal wastewater treatment plants which
will utilize the oxygen aeration process
are in various stages of design and con-
struction. The total amount of sewage to
be treated by these plants exceeds 1.5 bil-
lion gallons a day.





WHAT IS OXYGEN AERATION?

One common, or conventional, method
of treating wastewater is the activated
sludge process. This process—as all bio-
logical treatment processes—functions by
contacting wastewater with bacteria able
to break down organic material and there-
by reduce the amount of pollutants in the
wastewater. The bacteria utilized in the
activated sludge process to perform this
operation are contained in the material
settled out of a wastewater stream after
oxygen is introduced into the system.
This mass of settled solids, called activated
sludge, is then mixed with the wastewater
being treated. Introduction of oxygen in-
to the system, and mixing of the activated
sludge with the wastewater both occur in
the same tank, as can be seen from the
accompanying schematic diagram.

Historically, this required oxygen has been
provided by the introduction of atmos-
pheric air into the treatment system.
Oxygen gas, however, possesses certain
characteristics which can make its use, in
lieu of atmospheric air, advantageous. One
of these is the high partial pressure of
pure oxygen. Since air contains only a-
bout 21 percent oxygen, the use of pure
oxygen instead of air in that portion of
the treatment system needing oxygen in-
creases the oxygenation capacity by a fac-
tor of nearly five. As a result, smaller
aeration tanks can be used to treat the
same amount of wastewater. This utiliza-
tion of pure oxygen rather than atmos-
pheric air to provide the oxygen required
in treating sewage is oxygen aeration.

WHAT ARE THE APPLICATIONS
OF OXYGEN AERATION?

Oxygen aeration can be used for the con-
struction of new facilities and for up-
grading the capacity and performance of
existing overloaded secondary treatment
facilities. Several applications include:

1. Upgrading of existing overloaded ac-
tivated sludge plants by conversion
from air aeration to oxygen aeration.

2. Upgrading of existing trickling filter
plants by adding oxygen aeration as
a second stage biological step in the

¢ _ treatment system.

3.New plant construction, both with
and without primary sedimentation.


0, FEED

AGITATORS

2 9 96

AERATION TANK

RECYCLED SLUDGE

FINAL CLARIFIER

SCHEMATIC DIAGRAM OF MULTI-STAGE OXYGENATION SYSTEM

WHAT ARE THE ADVANTAGES
OF OXYGEN AERATION?

Potential benefits, depending on the spe-
cific installation and application, include:
. Improved reliability of treatment per-
formance

Reduced waste sludge production
Increased plant organic loading ca-
pacity

4. Improved resistance to toxic sub-
stances

More effective odor control

Reduced power requirements

Higher dissolved oxygen content in
the treated effluent

wn

aoe

Generally speaking, there is also an eco-
nomic advantage over conventional aera-
tion methods for plants with capacities
greater than 5 million gallons a day. In
the smaller capacity plants, the major ad-
vantages involve greater acceptance of un-
usually strong loads and greater treatment
process reliability.

WHAT'S INVOLVED?

This schematic diagram depicts the equip-
ment involved and operation of a typical
multi-stage oxygenation system. Basic dif-
ferences between this system and a con-
ventional air aeration system are the tank

covers and compressor units.

High purity oxygen (90-100%) enters the
first stage of the system and flows concur-
rently with the wastewater being treated
through the oxygenation basin. Pressure
under the tank covers is essentially atmos-
pheric and sufficient to maintain control
and prevent back mixing from stage to
stage. This allows for efficient oxygen uti-
lization at low power requirements. Mix-
ing within each stage can be accomplished
either with surface aerators or with a sub-
merged rotating sparge system (shown).

The selection of the number of stages and

ACTIVATED SLUDGE WASTEWATER TREATMENT PROCESS

PRETREATMENT

PRIMARY
CLARIFICATION

AERATION

CLARIFICATION

the type of mixing device are variables
that depend on waste characteristics, plant
size, land availability, treatment require-
ments and other similar considerations.

HOW MUCH DOES IT COST?

The chart below depicts representative
total treatment cost ranges for oxygen
aeration activated sludge plants. The costs
shown are for construction of new treat-
ment facilities and include operation,
maintenance and capital amortization
(5%%-25 years) costs for primary treat-
ment, secondary treatment, and sludge
handling and disposal facilities.

TOTAL TREATMENT COSTS.C/1000 GALLONS TREATED

OXYGEN AERATION

40 60
PLANT SIZE.MGD.

DISINFECTION