oEPA
United States
Environmental Protection
Agency
EPA/600/R-21/000 | October 2021 | www.epa.gov/research
Dual-Disinfection of
Wastewater Effluent with
Combined Peracetic Acid (PAA)
and Sodium Hypochlorite
Treatment:
A FULL-SCALE PILOT STUDY AT MILL
CREEK PLANT
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Dual-Disinfection of Wastewater Effluent with Combined
Peracetic Acid (PAA) and Sodium Hypochlorite Treatment:
A Full-Scale Pilot Study at Mill Creek Plant
by
Dr. Vasudevan Namboodiri
U.S. Environmental Protection Agency
Office of Research and Development
Center for Environmental Solutions and Emergency Response
Cincinnati, Ohio 45268
and
Dr. Achal Garg
Metropolitan Sewer District of Greater Cincinnati MSD
Cincinnati, Ohio
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Disclaimer
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development,
partially funded and managed the research described herein. APTIM Federal Services LLC supported
part of the analytical work under EPA Contract No. EP-C-15-010 as a subcontractor to Pegasus
Technical Services, Inc. This report has been subjected to the Agency's peer and administrative review
and has been approved for external publication. Any opinions expressed in this report are those of the
author(s) and do not necessarily reflect the views of the Agency; therefore, no official endorsement
should be inferred. Any mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Questions concerning this document, or its application, should be addressed to:
Vasudevan Namboodiri, Ph.D.
U.S. Environmental Protection Agency
26 W. Martin Luther King Dr.
Cincinnati, OH 45268, USA
Email: Namboodiri.Vasudevan@epa.gov
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Acknowledgements
The U.S. Environmental Protection Agency acknowledges the contributions of the following
individuals to this study and report:
Bruce Smith (Metropolitan Sewer District of Greater Cincinnati MSDGC, Cincinnati, Ohio)
Mohini Nemade, Sanaiya Islam, Lauren Questell, and Hannah Caroscio (MSDGC student
contractors)
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. To meet this mandate, EPA's research program is
providing data and technical support for solving environmental problems today and building a science
knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect
our health, and prevent or reduce environmental risks in the future.
The EPA's Center for Environmental Solutions and Emergency Response (CESER) within the Office of
Research and Development conducts applied, stakeholder-driven research and provides responsive
technical support to help solve the nation's environmental challenges. The Center's research focuses on
innovative approaches to address environmental challenges associated with the built environment. We
develop technologies and decision-support tools to help safeguard public water systems and
groundwater, guide sustainable materials management, remediate sites from traditional contamination
sources and emerging environmental stressors, and address potential threats from terrorism and natural
disasters. CESER collaborates with both public and private sector partners to foster technologies that
improve the effectiveness and reduce the cost of compliance, while anticipating emerging problems. We
provide technical support to EPA regions and programs, states, tribal nations, and federal partners, and
serve as the interagency liaison for EPA in homeland security research and technology. The Center is a
leader in providing scientific solutions to protect human health and the environment.
This study report describes development of a practical dual-disinfection approach for municipal
wastewater disinfection. This report summarizes the results from a wastewater treatment field study that
was conducted at the Metropolitan Sewer District of Greater Cincinnati's Mill Creek Facility.
Gregory Sayles, PhD.
Director, Center for Environmental Solutions and Emergency Response
EPA's Office of Research and Development
Cincinnati, Ohio
iv
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Table of Contents
Disclaimer mv
Acknowledgements iii
Foreword iv
List of Figures vi
Abbreviations vii
Executive Summary viii
1. Introduction 1
2. Methodology 3
2.1. Treatment Set-up 3
2.2. Experimental Design 6
2.3. Analytical Methods 6
3. Results and Discussion 7
3.1. Treatments with PAA Alone 7
3.1.1 PAA dose of 0.7mg/L 8
3.1.2 PAA dose of 1 mg/L 9
3.1.3 PAA dose of 1.1 mg/L 10
3.2 Dual Disinfection Treatment 11
3.3 Total Residual Oxidants (TRO) 13
4. Conclusions 14
5. References 15
Appendices 17
Appendix D - Quality Assurance/Quality Control (QA/QC) Measures 18
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List of Figures
Figure 2.1 - Simplified Mill Creek liquid treatment process 5
Figure 3.1 - Treatment of secondary effluent with PAA doses ranging from 0.5mg/L to 0.65mg/L..8
Figure 3.2 - Treatment of secondary effluent with 0.7mg/L PAA 9
Figure 3.3 - Treatment of secondary effluent with 1 mg/L PAA 10
Figure 3.4- Treatment of secondary effluent with 1.1 mg/L PAA 11
Figure 3.5 - Dual disinfection with 0.7 mg/L PAA + 0.4 mg/L NaOCl 12
Figure 3.6 - Geometric mean comparison of different treatment schemes 13
Figure 3.7 - Intermediate and delayed oxidant residual data 14
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Abbreviations
CFU
colony-forming unit
MSDGC
Metropolitan Sewer District of Greater Cincinnati
MCTP
Mill Creek Treatment Plant
MGD
million gallons per day
NaOCl
sodium hypochlorite
NPDES
National Pollutant Discharge Elimination System
OEPA
Ohio Environmental Protection Agency
ORD
Office of Research and Development
PAA
peracetic acid
TRO
total residual oxidants
EPA
United States Environmental Protection Agency
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Executive Summary
Peracetic acid (PAA) in combination with chlorination was shown to provide effective bacterial
reduction in secondary effluent during field study research conducted at the Mill Creek Treatment Plant
of the Metropolitan Sewer District of Greater Cincinnati, located in Cincinnati, Ohio. This study
compared PAA with sodium hypochlorite (NaOCl) chlorination and their combinations for the
disinfection of Escherichia coli in the treatment plant's wastewater.
Key findings:
~ This full-scale field study evaluated the effectiveness of PAA and NaOCl treatment for
secondary effluent disinfection. The treatment data is then compared with sequential dual disinfection
treatment using PAA followed by NaOCl. This treatment study showed that the PAA and chlorine
combination is very effective for municipal wastewater disinfection. A major advantage of dual
disinfection is the low residual oxidant content, better treatment efficiency, and low environmental
impact compared to separate individual treatments.
~ The field studies showed that the dual disinfection using PAA followed by chlorination provided
better disinfection compared to individual disinfection steps. The disinfection mechanism is different for
PAA and chlorination. For example, PAA is less effective in water with high oxygen demand where
chlorine will be helpful to achieve the treatment goals.
~ The sequential dual disinfection treatment using PAA followed by NaOCl has the potential to
lower chlorine usage, which reduces chlorinated disinfection byproducts in the discharge and avoids the
need for expensive dechlorination steps.
~ The author's recent studies showed that the PAA addition to the existing municipal wastewater
treatment train required very low capital investment. Economic savings can be expected from the
reduction of capital and operational expenses needed for dechlorination and chlorination storage needs
and consumption, respectively. In addition, PAA can be used to support facilities that use chlorination to
achieve better compliance.
viii
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i. Iini" hi, 11, -i,
In 2018, while renewing the National Pollutant Discharge Elimination System (NPDES) permit for
Metropolitan Sewer District of Greater Cincinnati's (MSDGC) Mill Creek Treatment Plant (MCTP), the
Ohio Environmental Protection Agency (OEPA) made key changes to the permit. Those changes
included replacing fecal coliforms with Escherichia coli as the monitoring biomarker for secondary
effluent disinfection during the recreational season (May 1- October 31). In addition, the weekly and
monthly geometric mean of E. coli limits were set to 240 colony-forming units (CFU)/100mL and 126
CFU/lOOmL. By contrast, in the old permit, the weekly and monthly fecal coliform limits were 400
CFU/lOOmL and 200 CFU/lOOmL, respectively. The total maximum oxidant residual (0.33 mg/L)
remained unchanged in the new permit. These changes in the permit prompted MSDGC to reevaluate its
capabilities and assess challenges in meeting new permit requirements. A review of the E. coli data
collected during the fall of 2018 at MCTP revealed that under current treatment conditions, MSDGC
would consistently fail to meet the revised permit's weekly and monthly E. coli limits. One solution was
to increase chlorination and dechlorinate after treatment to keep the total oxidant level below 0.33mg/L.
The dechlorination step would need new contact tanks and sodium bisulphate addition (which could
cause sodium pollution). The construction of new tanks would require large capital investments (20-30
million dollars). This prompted MSDGC to collaborate with ORD for developing cost-effective
alternative disinfection methods (Jacangelo, 2019; Acher, 1997; Lazarova, 1998 and 1999), including
the use of peracetic acid (PAA).
PAA is a chemical oxidizer that can be used as an alternative disinfectant for wastewater. The chemical
formula for PAA is CH3COOOH - essentially acetic acid with an extra oxygen molecule. Peracetic acid
is used in parts of Europe as a replacement for chlorine disinfection in wastewater, and it is currently
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used in North America in the food processing industry as a disinfectant for hard surfaces that have been
in contact with fruits, vegetables, meats, and eggs (Basu and Gatchene, 2009). Recently, PAA has been
evaluated as a replacement for chlorine to disinfect secondary effluent from wastewater treatment plants
(Jacangelo, 2019). PAA is commercially available as an aqueous quaternary equilibrium mixture of
acetic acid, hydrogen peroxide (H2O2), PAA, and water:
CH3COOH + H2O2 <-> CH3CO3H + H20
PAA is usually produced at concentrations of 5% -15%. Kitis (2004) reviewed the use of PAA as a
disinfectant for wastewater effluents since the 1980s and reported it to be an efficient bactericidal,
virucidal, fungicidal and sporicidal chemical. Typical PAA treatment concentrations for secondary
effluent are 0.50-2.0 mg/L, and enhanced primary effluent typically requires a PAA concentration of 5-
10 mg/L. PAA contact times are typically 10-30 minutes with most of the reaction occurring within the
first 10 minutes (Dancey, 2008). Peragreen Solutions and Solvay Chemicals have treated between 5 and
8 MGD of secondary effluent with PAA dosages not exceeding 1.5 mg/L at the wastewater treatment
plant in the City of Steubenville, Ohio (Maziuk et al., 2013). The disinfection action of PAA occurs
through mechanisms such as the release of nascent oxygen, which could oxidize essential enzymes for
cellular metabolism, disrupt cell membranes and transport mechanisms, and denature proteins in spores
(Kitis, 2004). A major advantage of PAA as a disinfectant is that it is not known to produce any harmful
disinfection byproducts (Liberti and Notarnicola, 1999; Namboodiri et al., 2016). Some limitations of
using PAA as a disinfectant include lower disinfection efficiency against some viruses and parasitic
oocysts as well as potential for regrowth of microbes since residual PAA contributes to organic carbon
as a food source in the effluent (Kitis, 2004; Crebelli, 2005).
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The author's previous bench, pilot, and field studies evaluated the effectiveness of PAA for treating
combined sewer overflow (CSO) and dual disinfection by combining PAA/ultraviolet (UV) and
PAA/chlorination for secondary effluent (Namboodiri et al., 2016 and 2020; Garg et al., 2017 and 2019).
The current full-scale pilot study was based on data collected from several bench-scale studies
conducted in the MSDGC laboratory with PAA and NaOCl. These laboratory studies indicated PAA
alone was a better disinfectant than NaOCl and could meet permit limits for both E. coli and total
residual oxidants (TRO). A third, potential dual disinfection treatment method, pre-treatment of
secondary effluent with NaOCl followed by PAA, was evaluated in the laboratory but was found to be
no more effective than NaOCl treatment alone at reducing E. coli numbers. Hence, this combination of
NaOCl followed by PAA treatment was not evaluated in the field pilot study. Objectives of this full-
scale plant-level pilot study were: 1) to determine if dual disinfection using PAA followed by NaOCl
was better than individual PAA or NaOCl treatments in reducing E. coli concentrations, and 2) to find
an optimal PAA followed by NaOCl dose combination in dual disinfection treatment to satisfy new
permit limits for E. coli and total oxidant residuals during the recreational season.
I' I' '111 ".!¦ >l>
This section describes the treatment set-up, experimental, and analytical methods.
I III -i ii||
This full-scale pilot study was conducted at MCTP from May to August 2019. During pilot study hours,
the primary MCTP disinfection system (i.e., NaOCl) was shut off, while at the same time the PAA
injection pump was activated to treat secondary effluent. At the conclusion of each day's testing, the
primary NaOCl disinfection system was turned on prior to shutting off the PAA injection pump. This
always ensured uninterrupted disinfection of secondary effluent.
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The location for injecting NaOCl to disinfect secondary effluent during normal operation is designated
as Location A in Figure 2.1. For the pilot study, however, Location A was selected to inject PAA using a
separate Model M-6 chemical feed pump (Blue-White Industries, Ltd, Huntington Beach, California).
Totes of PAA (PeroxyChem, Philadelphia, Pennsylvania) containing approximately 250 gallons of 15%
PAA were stored near the injection site under a tent to provide protection from the weather. For dual
disinfection tests, the NaOCl injection site was moved to Location B (Figure 2.1), with the Sampling
Station at Location C.
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M
BarRac
nne\ik
NaOCI Injection Point B
"Location B"
r\
PAA Totes
PAA Injection Point A
"Location A"
Figure 2.1. Simplified Mill Creek liquid treatment process. Treatment locations for injecting PAA ("A"), NaOCI ("B"), and
sampling station ("C").
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erimental Design
Secondary effluent was treated with the PAA alone, NaOCl alone, or various combinations of PAA
followed by NaOCl (dual disinfection).
The following strategies were applied to achieve the desired treatments:
PAA only treatment. The plant's NaOCl (chlorine source) pump at Location A (Figure 2.1) was turned
off and the PAA pump was turned on at this location. The pumping rate was set manually based on the
flow rate of the secondary effluent. The post-treatment samples were collected at the Sampling Station
(Location C) and kept for the time the flow reaches the discharge point. The holding time before
quenching was calculated using NPDES permit approved flow rate discharge chart. The samples were
then analyzed for residual oxidant content and microbiological analysis.
PAA followed by NaOCl Sequential Treatment (Dual Disinfection). Secondary effluent was treated first
with PAA followed by NaOCl. With the plant's primary NaOCl dosing pump shut off, the PAA dosing
pump was turned on at Location A. The NaOCl pump at Location B was turned on at the same time to
inject the desired dose of NaOCl. It took between two to five minutes for PAA-treated secondary
effluent from Location A to reach Location B where NaOCl was injected. The dual disinfection post-
treatment samples were collected at the Sampling Station (Location C) for residual oxidant and
microbiological analysis.
ical Methods
E. coli results were obtained using two analytical methods. For benchtop studies, the IDEXX Colilert®-
18 method was used (IDEXX Laboratories, Inc., Westbrook, Maine) (Appendix A). For field studies, the
membrane filtration method was applied (Standard Methods, method number 9222). Chlorine in samples
was measured using total chlorine analysis by HACH® Method 8167 N, N-diethyl-p-phenylene-diamine
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(DPD) colorimetric method (Hach, Loveland, Colorado) (Appendix B). Oxidant residuals were
measured as TRO after PAA or dual disinfection combination treatments; samples were analyzed using
an amperometric titrator. Analysis of PAA was carried out using PAA Vacu-Vials® ampoules and the I-
2020 PAA single analyte meter (CHEMetrics, Midland, Virginia) (Appendix C).
Two sets of TRO data were collected during the study: intermediate and delayed. Intermediate TRO
values represented the total oxidant levels in the secondary effluent three to five minutes (dependent on
flow rate) after adding PAA at Location A. Delayed residual measurements were made after a
predetermined holding period based upon the plant's flow rate. This predetermined delay represented the
time it took treated secondary effluent to reach the outfall at the Ohio River. After holding the samples
for the calculated delay time, one part of the sample was quenched for bacteriological analysis and the
second part was used for TRO measurements. Samples for all analytes were collected at the Sampling
Station (Location C).
I ¦ M111 • . I im I <1 ¦' 'I i
This report only presents the details of the field study results. The secondary effluent treatment
efficiency of PAA alone and with dual disinfection combinations was determined by measuring
(Standard Methods, method number 9222) the reduction of E. coli after treatment. Treatment doses for
PAA ranged from 0.5 mg/L to 1.2 mg/L. While multiple dual disinfection combinations were evaluated,
only one combination is detailed in this report.
I II ii ni merits wMli II II< ne
Although E. coli concentrations were significantly reduced with PAA doses between 0.5 mg/L and 0.65
mg/L, none of the 11 samples analyzed satisfied the permit limit of 126 CFU/100 mL (Figure 3.1). The
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lowest number of E. call observed after disinfection with doses between 0.5 mg/L and 0.65 mg/L was
160 CFU/100 mL. The geometric mean of these 11 samples was 889 CFU/100 mL (Figure 3.1).
5000
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Sample Collection Day
Figure 3,1 Treatment of secondary effluent with PAA doses ranging from 0.5mg/L to 0.65 mg/L. None
of the samples satisfied permit limit. The treatment achieved a geometric mean of 889 CFU/lOOmL.
3.1.1 PAA dose of 0.7mg/L
The lowest PAA dose to reduce E. coll below the new permit limit was found to be 0.7 mg/L. Of the ten
samples treated with this PAA dosage, four were between 40 CFU /100 mL and 110 CFLJ /100 mL. The
remaining six had a range of 140 CFU/100 mL to 300 CFU/100 mL. The geometric mean of these ten
samples was 123 CFU /100 mL, just below the new permit limit of 126 CFU/100 mL (Figure 3.2).
Earlier benchtop studies demonstrated a similar dose response and indicated that a minimum dose of 0.7
mg/L PAA would be required to meet new permit limits for li coli.
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Sample Collection Day
Figure 3.2. Treatment of secondary effluent with 0.7mg/L PAA. Of the ten samples
analyzed, four were below the permit limit. This treatment achieved a geometric mean of
123 colony forming units (CFU)/100 mL, just below the permit limit.
3.1.2 PAA dose of 1 mg/L
When secondary effluent was treated with 1 mg/L PAA, the average number of E. coli was reduced to
61 CFU/100 mL (Figure 3.3). Two samples in the 1 mg/L PAA treatment group exceeded the new
permit limit of 126 CFU/100 mL. These two samples (with 180 CFU/100 mL and 240 CFU /100 mL)
were collected during rain events with very high plant flow; normal plant flow ranges between 80 MGD
and 120 MGD. The flow rate was 200 MGD and 225 MGD during the first and second rain events,
respectively. At these high flow rates, the contact time for PAA was reduced to 14-15 minutes from an
average of 45 minutes during normal plant flow conditions. The reduced contact time was insufficient to
bring the E. coli concentrations below the revised permit limit. The nine remaining samples were
collected under normal flow conditions, and 1 mg/L PAA reduced the E. coli concentration to a
geometric mean of 61 CFU /100 mL.
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300
250
200
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3 100
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Sample Collection Day
Figure 3.3. Treatment of secondary effluent with 1 mg/L PAA. Of the 11 samples analyzed, 8
samples were below the permit limit, one just at the limit (130 CFU/100 mL) and two above the
limit. Both samples were collected when the flow in the plant was over 200 MGD during wet
weather.
240
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180
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3.1.3 PAA dose of 1.1 mg/L
The most effective PAA dosage was found to be 1.1 mg/L (Figure 3.4). All seven samples, under normal
flow rates, in this treatment group were between 40 CFU/100 mL and 90 CFU/100 mL E. coli with a
geometric mean of 60 CFU /100 mL.
10
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100
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Sample Collection Day
Figure 3.4. Treatment of secondary effluent with 1.1 mg/L PAA. All seven samples were
found to be less than the new permit limit of 126 CFU/100 mL with a geometric mean of 60
CFU/lOOmL.
3.2 Dual Disinfection Treatment
Bench scale studies showed combining PAA followed by NaOCl (dual disinfection) enhanced E. coli
kills. These pilot study findings confirmed the results of laboratory studies. It is noteworthy that dual
disinfection was most effective when NaOCl was added three to four minutes after PAA.
The combination of 0.7 mg/L PAA followed by 0.4 mg/L NaOCl was found to be the optimal dose to
meet the new permit limit for E. coli. This combination achieved a geometric mean of 29 CFU/100 mL
of E. coli (Figure 3.5). In comparison, 1.1 mg/L PAA alone achieved a geometric mean of 61 CFU /100
mL E. coli (Figure 3.4). This finding has significant implications for achieving higher treatment
efficiency at lower cost. Although both treatment regimens (i.e., 1.1 mg/L PAA or 0.7 mg/L PAA + 0.4
11
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mg/L NaOCl) used equal amounts of total oxidants (1.1 mg/L), the dual disinfection treatment was more
effective. In the dual disinfection strategy, only 0.7 mg/L PAA was used compared with 1.1 mg/L PAA
in the PAA-only treatment or about 38% less PAA. This reduction in the requirement for PAA can have
a significant impact on the total cost of treatment. The use of dual disinfection did not increase the final
total oxidant residuals, which remained at 0.2 mg/L or less.
140
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126 CFU/100 mL
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70
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30 Mean 29
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12
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Sample Collection Day
Figure 3.5. Dual disinfection with 0.7 mg/L PAA + 0.4 mg/L NaOCl. Sequential treatment
with PAA and NaOCl had significant impact on E. coli kill rates. All 10 samples were below new
permit limit with a geometric mean of 29.
Figure 3.6 presents a graphical comparison of geometric means from three of the different treatment
schemes. The blue bar is the lowest dose of PAA alone to reduce E. coli below the new permit limit (0.7
mg/L). The orange bar is the most effective PAA alone dosage (1.1 mg/L). Finally, the grey bar is the
optimal dual disinfection combination of 0.7 mg/L PAA followed by 0.4 mg/L NaOCl.
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Figure 3.6. Comparing geometric means of different treatment schemes. Benchmark
PAA concentrations compared with dual disinfection.
3.3 Total Residual Oxidants (TRO)
After collection at the sampling station (Location C, Figure 2.1), samples were analyzed for intermediate
and delayed residuals. Intermediate residual measurements were made immediately. These TRO values
represented the total oxidant levels in secondary effluent three to five minutes (dependent on flow rate)
after adding PAA at Location A. Delayed residual measurements were made after a predetermined
holding period based upon the plant's flow rate. This represented the time it took for treated secondary
effluent to reach the outfall at the Ohio River, and the TRO levels being discharged therein.
Three delayed TRO samples, all from PAA only treatments, failed to meet the new permit's residual
oxidant limit of 0.33 mg/L (Figure 3.7). Those three samples were collected during high flow conditions
(between 200 MGD and 265 MGD), which resulted in delay times of 12-14 minutes. Normal plant flow
is 80-120 MGD with an average delay time of 45 minutes. All TRO sample data from dual disinfection
treatment (0.7 mg/L PAA + 0.4 mg/L NaOCl) was found to comply with the new permit's oxidant
residual limit.
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• Intermediate • Delayed
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Figure 3.7. Intermediate and delayed oxidant residual data. Only three delayed TRO
measurements failed to meet the new permit limit of 0.33 mg/L.
4. Conclusions
This full-scale pilot study evaluated the effectiveness of individual PAA and NaOCl treatments for
secondary effluent disinfection and compared them to sequential dual disinfection using PAA followed
by NaOCl. The study optimized PAA and NaOCl dose combination to satisfy new OEPA permit limits
for E. coli and total oxidant residuals during the recreational season.
• Dual disinfection with PAA followed by sodium hypochlorite is significantly more effective
than individual PAA or sodium hypochlorite treatments.
• Treatment with 0.7 mg/L PAA followed by addition of 0.4 mg/L NaOCl three to four
minutes later was found to be the optimal dose combination.
• The above dual disinfection combination achieved a post-treatment geometric mean E. coli
concentration of 29 CFU/lOOmL with total oxidant residuals <0.2 mg/L.
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• The sequential disinfection using PAA followed by NaOCl treatment satisfied both E. coli
and residual oxidant NPDES permit limits for the MCTP. Therefore, PAA can be used to
support facilities that use chlorination to achieve better disinfection compliance.
!:>. I • 'li.v
Acher, A., Fischer, E., Turnheim, R., and Manor, Y. 1997. Ecologically friendly wastewater disinfection
techniques. Water Research 31 (6), 1398-1404.
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Dancey, K. 2008. Peracetic Acid: A New Disinfection Approach. Presented at PNCWA [Pacific
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Kitis, M. 2004. Disinfection of wastewater with peracetic acid: A review. Environment International 30
(1), 47-55.
Lazarova, V., Savoye, P., Janex, M. L., Blatchley III, E. R., and Pommepuy, M. 1999. Advanced
wastewater disinfection technologies: State of the art and perspectives. Water Science and Technology
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wastewater disinfection technologies: Short- and long-term efficiency. Water Science and Technology
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Garg, A., Namboodiri, V. and Au K-K. 2017. Disinfection Pilot Trial for Little Miami WWTP.
EPA report, EPA/600/R-17/170.
Namboodiri, V., Murray, D., Alvarez, F. and Cypcar, C. 2020. A Pilot Study of On-site Generated
Peracetic acid and its Application for Municipal Wastewater Disinfection. EPA report, EPA/600/R-
20/135
Crebelli, R., Conti, L., Monarca, S., Feretti, D., Zerbini, I., Zani, C., Veschetti, E., Cutilli, D.,
and Ottaviani, M. 2005. Genotoxicity of the disinfection by-products resulting from peracetic acid- or
hypochlorite-disinfected sewage wastewater. Water Research, 39(6): 1105-13.
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Appendices
Table A-l. ATPTIM and EPA's Testing and Evaluation (T&E) Facility's Standard Operating Procedures
(SOPs)
APPENDIX A
APTIM T&E SOP 310 ("Total Coliform and
E. coli Analysis Using IDEXX Colilert® 18
Method")
J
\
o
PDF
T&E SOP 310
TotalColiform & Ecoli
APPENDIX B
APTIM T&E SOP 504 (FREE CHLORINE &
TOTAL CHLORINE ANALYSIS, "Free
Chlorine Analysis by HACH® Method 8021
And Total Chlorine Analysis by HACH®:
Method 8167 N.N-diethyl-p-phenylene-
diamine (DPD) Colorimetric Method; 0.02 to
2.00 mg/L C12 ")
'j?
PW
T&E SOP 504 Free
Chlorine And Total Ch
APPENDIX C
APTIM T&E SOP 511 (PERACETIC ACID
BY CHEMETRICS, "Peracetic Acid (PAA)
by CHEMetrics® DPD Method")
\
POf
T&E SOP 511
Peracetic Acid By CHE
T&E, EPA's Testing and Evaluation Facility, Cincinnati, Ohio; SOP, standard operating procedure
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Appendix D - Quality Assurance/Quality Control
(QA/QC) Measures
D.l Introduction
An important aspect of technology testing is the quality assurance/quality control (QA/QC) procedures
and requirements developed. Careful adherence to the procedures detailed in the quality assurance
project plan (QAPP) enables researchers to evaluate the performance of dual disinfection treatment
using peracetic acid (PAA) followed by NaOCl to disinfect secondary wastewater and present the data
in this report. The primary measures of evaluation for data quality were representativeness, accuracy,
and precision.
D.2 Analytical Procedures
The Metropolitan Sewer District of Greater Cincinnati (MSDGC) staff conducted the full-scale field
study that was created specifically for these evaluations and performed any sample analyses on site that
needed to be made immediately. APTIM staff conducted the E. coli analyses following Aptim T&E
standard operating procedure (SOP) 310 "Total Coliform and E. coli Analysis Using IDEXX
Colilert®18 Method" (Appendix A). Analytical methods for the laboratory analyses are presented in
Table D-l.
D.3 Sample Handling
Samples were collected by MSDGC and were labeled with unique sample names in the format specified
in the EPA-approved QAPPs. Samples were transferred by MSDGC from the study location to APTIM
at EPA's Test and Evaluation (T&E) Facility in Cincinnati, Ohio, for E. coli analyses within 6 hours of
sample collection in hard-sided coolers with ice. All samples were analyzed within the sample holding
time specified in the QAPP.
D.4 Sample QA/QC
The calibration of analytical instruments and the analyses of parameters complied with the QA/QC
provisions of the EPA-approved QAPP used in this evaluation. Sample volumes, preservation, and
holding times are shown in Table D-2. Laboratory QA/QC checks for the chemical and microbiological
analyses are shown in Table D-3.
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The APTIM QA/QC requirements specified in the referenced T&E SOP (Table A-l, following the
Appendices heading, above) were compliant with those stated in the EPA-approved QAPPs for each
respective parameter. The SOPs implemented at the T&E Facility for the chemical and microbiological
analyses conducted for this evaluation are provided as attachments in the EPA-approved QAPP.
Table D-l. Measurements and Analytical Methods
Measurement
Analytical Method/ SOP
PAA
Chemetrics, Inc. K-7913
Total Chlorine
Total Chlorine Analysis by HACH®
Method 8167 DPD Colorimetric Method
E. coli
APTIM SOP 310 and Standard Methods
#9222
Total Residual Oxidants
Hach Amperometric titrator Model AT 1000
Temperature
Thermometer
Flow rate
Non-Contact LaserFlow® Velocity Sensor
DPD = N,N-diethyl-p-phenylene-diamine, SOP = standard operating procedure
Table D-2. Sample Volumes, Preservation, and Holding Times
Measurement
Sample
Container
Volume of
sample
Preservation
Holding Time
PAA
Glass beaker
100 mL
None
None. Analyze
immediately
after sampling.
Total Chlorine
Glass beaker
100 mL
None
None. Analyze
immediately
after sampling.
E. coli
Plastic
100 mL
Sodium thiosulfate, 4°C
24 hours
Total Residual
Oxidants
Glass beaker
100 mL
None
None. Analyze
immediately
after sampling.
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Measurement
Sample
Container
Volume of
sample
Preservation
Holding Time
Temperature
Glass beaker
50 mL
None
None. Analyze
immediately
after sampling.
D.5 Documentation
Laboratory activities were documented using standardized datasheets, logbooks, and laboratory
notebooks. Laboratory data reports were entered into Microsoft™ Excel® spreadsheets. These
spreadsheets were used to calculate the mean, standard deviation, and ranges, as applicable.
D.6 Data Review
Calculations performed on a computer were checked initially by the analyst for gross error and
miscalculation. The calculations and data entered into computer spreadsheets were checked by a peer
reviewer for accuracy by printing out the calculation or data spreadsheet and checking the calculation by
hand or comparing each entry of data with the original.
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Table D-3. QA/QC Checks
Measurement
QA/QC
Check
Frequency
Acceptance
Criteria
Corrective Action
PAA
Check
Standard
(2.5 mg/L)
Before analysis, after
every 10 samples, and at
the end of batch analysis
±10% of
acceptance criteria
Discard data point, repeat
experiment if insufficient data
points
Duplicate
Once per batch of 10
RPDa<30%
Repeat analysis on the same
sample; if sample volume does not
allow, choose another sample and
document accordingly
Total Chlorine
Check
Standard
(2.5 mg/L)
Before analysis, after
every 10 samples, and at
the end of batch analysis
±10% of
acceptance criteria
Discard data point, repeat
experiment if insufficient data
points
Duplicate
Once per batch of 10
RPDa<30%
Repeat analysis on the same
sample; if sample volume does not
allow, choose another sample and
document accordingly
E. coli
Lab blank
Once per counting
session
0 MPNb/tray
Investigate lab technique
Reanalyze blank
Positive
control
Once per counting
session
±10 fold of the
spiking suspension
Investigate lab technique
Re-analyze the spiking suspension
and change it if necessary
Negative
control
Once per counting
session
0 MPN/tray
Investigate lab technique
Reanalyze buffer and change it if
necessary
Total Residual
Oxidants
Check
Standard
(2.5 mg/L)
Before analysis, after
every 10 samples, and at
the end of batch analysis
±10% of
acceptance criteria
Discard data point, repeat
experiment if insufficient data
points
Duplicate
Once per batch of 10
RPDa<30%
Repeat analysis on the same
sample; if sample volume does not
allow, choose another sample and
document accordingly
Temperature
Calibration
verification
Beginning of project
±1°C
Verify accuracy against NIST or
NIST-traceable thermometer
Flow Rate
Calibration
verification
Beginning of project
Full-scale factory-
calibrated accuracy
of±l%
Initially at the factory; checked by
measuring volume and time prior
to testing
a: Relative Percent Difference (RPD)
b: Most Probable Number (MPN)
D.7 Data Quality Indicators
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The quality of data generated for this system performance evaluation is established through three
indicators of data quality: representativeness, accuracy, and precision.
D. 7.1 Representativeness
Representativeness is a qualitative term that expresses "the degree to which data accurately and
precisely represent a characteristic of a population, parameter variations at a sampling point, a process
condition, or an environmental condition." Representativeness was ensured by consistent execution of
the test protocol for each challenge, including timing of sample collection, sampling procedures, and
sample preservation. Representativeness was ensured by following standard operating procedures and
published methods to provide reproducible results and represents the most accurate and precise
measurement the analytical method is capable of achieving.
D. 7.2 Accuracy
Accuracy was quantified as the percent recovery of the parameter in a sample of known quantity.
Accuracy was measured through use of certified standards during calibration of an instrument.
The following equation was used to calculate percent recovery:
Percent Recovery = 100 x [(Xkn own — Xmeasured)/Xknown]
Where:
Xknown — known concentration of the measured parameter
Xmeasured = measured concentration of parameter
The EPA-approved QAPP specifies the frequency of calibration checks as well as the accuracy
acceptance criteria for the chemical analyses. Calibration and calibration check requirements specified
in the QAPP were achieved for all analyses.
D. 7.3 Precision
Precision refers to the degree of mutual agreement among individual measurements and provides an
estimate of random error. At least one out of every ten samples for THMs, HAAs, sodium, pH, PAA,
chlorine, and solids were analyzed in duplicate as part of the analysis batch. Precision of duplicate
analyses was measured using the following equation to calculate RPD:
RPD =
*1
"*2
*1
+ S2
200
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Where:
51 = sample analysis result; and
52 = sample duplicate analysis result.
Because the microbiological analyses (E. coli, fecal coliform, and Enterococci) are measured on a
logarithmic scale, typical RPD calculations might result in higher than the expected RPD values. For
this reason, the RPD was calculated after transforming the concentrations with a common logarithm
(base 10):
RPD =
log S1 - log S2
log Sx + log S2
x 200
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