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r	United States Environmental Protection Agency
^	~r0	September 2012
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%	^ Alternative Disinfection Methods Fact Sheet:
% ^s° Peracetic Acid
^ pro^
DESCRIPTION
Disinfection is considered to be the primary
mechanism for the inactivation/destruction of
pathogenic organisms to prevent the spread of
waterborne diseases to downstream users and
the environment. It is important that
wastewater be adequately treated prior to
disinfection in order for any disinfectant to be
effective. Table 1 lists some common
microorganisms found in domestic wastewater
and the diseases associated with them.
Table 1: Infection Agents Potentially Present In
Untreated Domestic Wastewater
ORGANISM
RELATED
DISEASE
Bacteria:
Escherchia coli
Gastroenteritis
(enterotoxigenic)
Leptospira (spp.)
Leptospirosis
Salmonella
(2,100 serotypes)
Salmonellosis
Salmonella typhi
Typhoid fever
Shigella (4Spp.)
Shigelloisis
(bacillary dysentery)
Vibrio Cholerae
Cholera
Protozoa:
Balantidium
Coili
Balantidiasi
Cryptosporidium
(Parvum)
Cryptosporidiosis
Entamoeba
histolytica
Amebiasis
(amoebic dysentery)
Table 1: Continued
Giardia Lamblia
Giardiasis
Helminthes:
Ascaris
lumbricoides
Ascariasis
T. Solium
Taeniasis
Trichiura trichiura
Taeniasis
Viruses:
Enteroviruses (72
types) e.g. Polio,
Echo, Coxsackie
Gastroenteritis, heart
abnormalities,
meningitis
Hepatitis A
Infectious Hepatitis
Norwalk Virus
Gastroenteritis
Rotavirus
Gastroenteritis
Source: Adapated from Crites and Tchobanoglous,1998
The effectiveness of a Peracetic Acid (PAA)
disinfection system depends on the characteristics
of the wastewater, the concentration of PAA, the
amount of time the microorganisms are exposed to
the PAA, and the reactor configuration. For any
one treatment plant, disinfection success is directly
related to the concentration of colloidal and
particulate constituents in the wastewater. PAA is a
strong oxidant and virucide.
The mechanisms of disinfection using PAA
include:
• Direct oxidation/destruction of the cell
wall with leakage of cellular constituents
outside of the cell.

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Choosing a suitable disinfectant for a treatment
facility is dependent on the following criteria:
•	Ability to penetrate and destroy infectious
agents under normal operating conditions.
•	Absence of toxic residuals and mutagenic or
Carcinogenic compounds after disinfection.
•	Safe and easy handling, storage, and
shipping.
When PAA decomposes in water, the free radicals
hydrogen peroxyl (HO2) and hydroxyl (OH) that are
formed have great oxidizing capacity and play an
active role in the disinfection process. It is
generally believed that the bacteria are destroyed
because of protoplasmic oxidation resulting in cell
wall disintegration (cell lysis). The effectiveness of
disinfection depends on the susceptibility of the
target organisms, the contact time, and the
concentration of the PAA.
APPLICABILITY
To reach high levels of disinfection of
wastewaters, the concern about the formation of
halogenated disinfection byproducts (DBPs) has
become more and more of an issue. The need for an
economical and relatively simple retrofit to an
Table 2: Residual PAA and Related Fecal
Coliform Counts in the Contact Basins
existing wastewater treatment facility has become
apparent. The use of peroxygen chemical
compounds has been practiced for years in
Europe, but in the last several years water
treatment companies have been considering the
use of peracetic acid (PAA) as an alternative to
halogenated disinfection chemicals (such as
chlorine based products).
Peracetic acid is an equilibrium mixture of acetic
acid and hydrogen peroxide and water CH3COOH
+ H202~ CH3COOOH + H20. Commercially
available PAA has a stabilizer to increase its
storage life. The problem is to demonstrate that
the use of PAA is: An effective disinfection
compound that does not generate harmful DBPs; A
more rapid acting disinfectant than chlorine based
disinfectants; That PAA can be economically
retrofitted and/or work in series with an existing
disinfection system; That PAA dissipates rapidly
and does not generate harmful disinfectant
byproducts even if overdosed.
RESULTS
Some of the results of the actual study using PAA
as a disinfectant are shown in Table 2.
Simple Point
Average PAA Residual
Fecal Coliform

(ppm)
(cfu 100ml)
Secondary Effluent
not applicable
4S:000
1
0,9
13,680
2a
0.6
4,040
2b
0.5
3.620
3a
0.3
2:600
31)
r 1
O
2340
4a
0.1
1,800
4b
0.1
1.480
5
0
580

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Outfall to River
Sampling Point 1
Shows Direction of Effluent Flow
Figure 1: Disinfection Schematic
The results of these tests indicate that PAA is a fast
acting disinfectant. As shown in Table 3, the
initial fecal coliform counts were reduced 10 fold
within the first 8-10 minutes estimated residence
time after contact with the product (sample points
2a and 2b). Additionally, all PAA was consumed
prior to discharge (sample point 5), demonstrating
the lack of persistence of the PAA.
Table 3: Residual PAA in contact tanks and
river outfall at a 5 ppm dose rate

Simple Point
Average PAA Residual

(ppm)
I
n-a
2a
126
2b
1.21
3a

3b

4a

4b

5

Outfall at River
.42

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During the 5 ppm dose test, the flow rate of the
"3
effluent increased to 5678 m / day which
decreased the residence time to one hour. The PAA
dose rate was verified to give a dose rate of 5 ppm;
however, the highest number recorded during this
test was 1.26 ppm. A sample at the mixer could
not be obtained. The PAA decomposed rapidly
with 0.42 ppm detected at the outfall. The purpose
of the 5 ppm test was for river water testing;
therefore no intermediate samples were taken. The
final test was a repeat of the 1 ppm test that was
performed in 2002. The results of this 1 ppm dose
are shown in the Table 4 below:
Table 4: Residual PAA in contact tanks and river
outfall at a 1 ppm dose rate
Sample Point
Average PAA Residual

(ppm I
1
n a
2a
0.8
2b
0.9
3a
0.3
3b
0^.4
4a
0.25
4b
0.25
5
0
Outfall at River
0^
During the 1 ppm dose study, the flow rate of the
effluent varied from 2271 to 4542 m3/day. This
gave a residence time of between 67 and 133
minutes. All of the PAA was consumed before the
wastewater reached the Huron River. These results
are similar to the ones from the same test performed
in 2002.
CASE STUDY: Frankfort, KY
The Frankfort, KY wastewater treatment plant
evaluated PAA for use as a temporary disinfectant
during an upgrade of their existing wastewater
disinfection system (ozone). In 1980 the Frankfort
wastewater treatment plant converted from
chlorine gas to ozone for disinfection.
The plant was then upgraded from a 6.6 MGD
plant to its current capacity of 9.9 MGD. In 2005
the decision was made to build a new higher
capacity ozone generator in response to the higher
capacity of the plant. Replacing the ozone
generator necessitated a temporary disinfection
technology during the 6 months between shut-
down of the old generator and start-up of the new
one.
After evaluating several disinfection technologies,
including sodium hypochlorite and sodium
bisulfite, the city went out to bid for a disinfection
technology and PAA was chosen. This was the
first commercial use of PAA for wastewater
disinfection in the United States.
•	The wastewater traveled through a static
mixer and a disinfection chamber with a 26
minute contact time at permit flow. (See
Figure 1).
•	The target dose rate was automatically held
constant based on the final effluent flow.
•	Peracetic acid residuals at the discharge point
were determined via a Chemetrics K-7905
test kit by Frankfort laboratory personnel.
•	Bacterial analyses were performed daily by
Frankfort laboratory personnel via the
filtration method.
•	BOD and pH analyses were taken daily by
Frankfort laboratory personnel.
RESULTS OF THE CASE STUDY
•	Within design flow conditions PAA 12%
peracetic acid solution was effective at
controlling fecal coliforms and E. coli. at a
target dose of 0.7 ppm

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•	Effluent treated with PAA passed acute
toxicity tests for Ceriodaphnia dubia.
•	Treatments costs with PAA were
competitive to disinfection with sodium
hypochlorite and sodium bisulfite.
•	Residual PAA in the wastewater at
discharge was less than 1 ppm thereby
eliminating the need of a neutralization
step.
•	No measurable effect was observed by
Frankfort laboratory personnel on pH and
BOD by the use of PAA for disinfection.
Kitis, M., 2004. Disinfection of wastewater with
Peracetic acid: a review. Environ. Int. 30, 47-55.
Metcalf & Eddy, Inc. 1991. Wastewater
Engineering: Treatment, Disposal and Reuse. 3d
ed. The McGraw-Hill Companies. New York,
New York.
US EPA, 1999. Combined sewer overflow
technology fact sheet. Chlorine disinfection. EPA
832-F-99-034. Office of Water, Washington, DC.
COSTS
Peracetic acid is applied to the wastewater process
from a bulk or intermediate storage vessel directly
into the wastewater. Typically a pump is used to
transfer the PAA from the storage vessel into the
secondary effluent. Good dispersion/mixing can
improve the effectiveness of the amount of PAA
added. The injection rate is controlled by
proportional flow control from a 4-20 mA signal
sent from the wastewater utility effluent flow
measurement. Most systems in the USA receive
PAA in containers not larger than 300 gallon one-
way disposable totes. The single most expensive
item (for tote systems) is a flow paced pump skid
that cost less than $50,000 for a 50 MGD facility at
4 ppm PAA.
REFFERENCES
Gehr, R., Wagner, M., Veerasubramanian, P.,
Payment, P., Disinfection efficiency of Peracetic
acid, UV and ozone after enhanced primary
treatment of municipal wastewater. Water Res. 37,
4573-4586.
Some of the information presented in this fact
sheet was provided by the manufacture or
vendor and could not be verified by EPA. The
mention of trade names, specific vendors, or
products does not represent an actual or
presumed endorsement, preference, or
acceptance by the U.S. EPA or Federal
Government. Stated results, conclusions, usage,
or practices do not necessarily represent the
views or policies of the U.S. EPA.
US Environmental protection Agency
Office of Wastewater Management
EPA 832-F-12-030

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