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The Application and Measurement of PeraceticAcid for Wastewater Disinfection2016 Good Laboratory Practices Conference
Joanne Carpenter, CHEMetrics, Inc.
Philip Block, Ph.D, PeroxyChem
Audience Survey
• Any audience members using PAA
disinfection at their plants?
• Any audience members working at
plants that have plans to study PAA
disinfection?
PAA Buzz
• PAA Benefits/Cons
• PAA Chemical/Physical Properties
• PAA Applications
• PAA Vendors
• Consulting Firms involved with PAA wastewater contracts
• Regulatory Status
• Stiles WWTP Case Study
• WERF Research Grant/ Design and Implementation of Peracetic Acid for Municipal Water and Wastewater Related Processes (LIFT14T16)
• Methods of Measurement
PAA Benefits Relative to Chlorine
• Replaces chlorine disinfection
• Broad spectrum of antimicrobial activity, (effective bactericide, fungicide, and sporicide)
• Fast disinfection kinetics
• Lower aquatic toxicity profile
• Decomposes to hydrogen peroxide (H2O2) and acetic acid which subsequently breaks down to oxygen and water
• Lack of disinfection by-product, (DBPs) formation
• Oxidant demand typically lower than chlorine
• Does not persist in environment so quenching is not required
• Minimal pH dependence
• Long shelf-life
• Requires local DEQ approval
• Does not maintain a residual
• Buried piping is not recommended to facilitate repairs if a
leak should develop
PAA Cons
PAA Electrochemical Oxidation
Potential Ranking
PAA Applications
• Widely used in Europe for wastewater disinfection
• Tertiary disinfectant
•Combined Sewer Overflow (CSO) disinfectant
• In conjunction with UV disinfection
• Lagoon disinfectant
PAA Applications, cont’d
• Used as disinfectant in food processing, beverage,
medical, pharmaceutical, textile and pulp and
paper
• Liquid sanitizer for surface disinfection in
clinical/medical facilities
PAA Disinfection Mode of Action
• Denatures bacterial, viral, yeast and spore proteins
• Disrupts cell wall permeability
• Oxidizes sulfhydryl and sulfur bonds in proteins, enzymes
and other metabolites
• Efficacy dependent on usage rate and contact time
• Synergistic effect of PAA and H2O2 on deactivation of
endospores – Mark J. Leggett et al., Applied and Environmental Microbiology, Feb.
2016 vol. 82, no. 4
PAA Chemical Properties
• Commercially available as an equilibrium mixture of:• Peracetic acid 12-15%
• Hydrogen peroxide 18.5 – 23%
• Inert ingredients • acetic acid ~18% • water ~51%
• CH3CO2H + H2O2 ⇌ CH3CO3H + H2O
Acetic Acid Hydrogen Peroxide PAA Water
• PAA, Peroxyacetic Acid, Ethaneperoxoic acid, Peroxide of Acetic Acid
Physical Properties of a 15% by wt. Solution
• Clear, colorless liquid
• Pungent, stinging, acetic acid odor
• pH < 1
• Completely soluble in water
• Density, 1.15 g/mL at 20°C
• Freezing point, -56°F (-49°C)
• Boiling point, 226°F (108°C)
• Flash point, 154°F (68°C) closed cup
• Strong oxidizer
PAA Vendors
• PeroxyChem, VigorOx WWT II
• Solvay, Proxitane
• EnviroTech, BioSide
• EcoLab (no products labeled for wastewater disinfection)
Source:
• CDM Smith
• CH2M Hill
• MWH Global
• EPA Office of Pesticide Programs has approved 4 PAA
products for use as a wastewater disinfectant. The product
label includes target application and residual concentration
ranges.
• State regulatory agencies have to figure out key PAA
disinfection monitoring parameters for permits.
• EPA Office of Wastewater has not published/approved
method of analysis for PAA.
1. NW Langley WWTP, Metro Vancouver, British Columbia
2. St. Augustine WWTP, St. Augustine, FL
3. Largo FL
4. City of Steubenville WWTP, Steubenville, OH
5. Mayport Naval Facility, Jacksonville, FL
6. Whitehouse WWTP, Whitehouse, TN
7. Flagler Beach WWTP, Flagler Beach, FL
8. Three Rivers Regional WWTP, Longview, WA
9. Tri Cities WWTP, Clackamas, OR
10. M.C. Stiles WWTP, Memphis, TN
11. Gulf Coast Water, Houston, TX
12. Bolling Green, KY
13. Tullahoma, KY
14. Hoboken NJ
15. And more.
• VigorOx WWTII
• CDM Smith/PeroxyChem
• Evaluation of impact of water quality on PAA demand with
time
• pH
• Suspended solids
• Organic matter
• Temperature
• M.C. Stiles wastewater treatment plant, Memphis, TN
Disinfection Contact Tanks
Screening
& Grit Chambers
Final Clarifiers
Contact –Stabilization
Tanks
Final Clarifiers
coarse and fine bar
screening
contact –
stabilization process
secondary
clarification
no current
disinfection (contact
channel is in place)
discharge to river
• Combined municipal and industrial components
• Industrial wastewater is highly variable, across many
industries
• Non-biodegradable molecules that add to oxidant demand
• Very low % UVT
• Time-dependent change in water quality
Variability in wastewater color in effluent
Parameter
Daily Performance Data
Minimum observed
Average or mean1
Maximum observed
Daily Flow2 (MGD) 58 94 232
BOD3 (mg/L) 5 34 144
TSS3 (mg/L) 1 22 103
pH4 (s.u.) 6.5 7.2 8.1
E. coli5 (cfu/100mL) 1.3 x 104
6.0 x 105
(4.4 x 105 as geomean)
1.1 x 107
Apparent color6
(PtCo units)29 749 2084
True color6
(PtCo units)24 619 2000
Apparent UVT6 (%) 0 9.3 36
Filtered UVT6 (%) 0.6 16 71.9
• large variation in water quality
• very low % UVT
Historical effluent water quality characteristics
PAA treated side
Untreated side
PAA
Probe 1
PAA
Probe 2
PAA Probe 3
Effluent Influent
BFM
E Coli
Influent
E Coli
Effluent
E Coli
Mid
Color
UVT
pH / temp
COD
PAA
Dose
point
• Full scale 6 month 5 phase dose control demonstration
trial
• Disinfection contact tank was split – one side served as
a control (no PAA treatment)
Phase 1 • Conducted over 2 week period
• PAA flow paced
• Continuous monitoring using on-line analyzers
• Color
• ORP
• % T @ 254 nm
• pH
• Temperature
• COD
• Grab Samples - E. Coli counts and COD (used to calibrate COD sensor)
• PAA monitoring @ influent and effluent
• Each parameter was correlated with PAA demand
• Dosing algorithm was developed for each parameter
Phase 2
• Dose control algorithm based on color was utilized
• Disinfection performance over wide range of effluent color
and flow rates was evaluated
• Conducted over 2 week period
Phase 3
• Dose control algorithm based on COD was utilized
• Disinfection performance over wide range of effluent COD
and flow rates was evaluated
• Conducted over 2 week period
• At conclusion of Phase 3, an algorithm was selected for
further study based on the best disinfection performance
Phase 4
• Dose control algorithm based on color was chosen
• Algorithm adjusted to maximize disinfection performance
while minimizing PAA dose.
• Conducted over month long period
Phase 5
• Refined dose control algorithm developed during Phase 4
was validated over month long period.
• Meet permit limits for E. coli, (monthly geometric mean < 126
cfu/100 mL)
• Flow ranged from 75 to 130 MGD
• PAA dose concentration ranged from 12 – 16 ppm
• Influent E. coli concentrations > 1.2 x 106 cfu/100 mL measured
• Daily sampling
Phase 5 Results
• All samples measured < daily maximum (487 cfu/100 mL)
• One sample exceeded monthly geometric mean limit @ 204
cfu/100 mL
• Geometric mean for all data collected over 30 day period
was 4 cfu/100 mL
• Excellent disinfection control was maintained during periods
of high color and high influent E.coli concentrations
Phase 5 Results, cont’d
• Trial successfully demonstrated a dose pacing plus feed
forward algorithm can provide continuous disinfection while
minimizing PAA chemical costs.
• Allowed engineers opportunity to learn important factors for
final design of the permanent full-scale PAA disinfection
system
• What is the effectiveness of PAA on various wastewater effluents related to the inactivation of E. coli and viruses?
• What impacts does PAA have on pH, cBOD, COD, TOC, DO, and solids?
• Does the temperature of the wastewater effluent influence the effectiveness of PAA?
• What are the effects of PAA on freshwater aquatic life?
• What other uses can PAA have in wastewater treatment (i.e., controlling algae, filamentous organisms)?
• What are PAA’s effectiveness and storage considerations during wet weather conditions?
• Is PAA a viable “backup” alternative to disinfection methods currently in place at facilities?
Why measure PAA?
1. Critical for the proper dosing of PAA to meet target
microbial reduction targets.
2. Monitoring is necessary to ensure regulatory water quality
limits are being maintained, (typically around 1 ppm).
PAA Measurement Techniques
1. In-situ probes (ppm to %)
2. Ceric Sulfate/Iodometric (dual) titration (%)
3. DPD colorimetric method (ppm)
(EPA Method 330.5 or Standard Methods 4500 Cl2)
• In-situ probes/Prominent Dulcotest CTE
• Real time continuous measurements
• Uses a membrane capped amperometric two electrode sensor
• Platinum working electrode
• Silver halide coated reference electrode
• Sample diffuses through the membrane → potential difference
1. Must be calibrated against another reference measurement on
periodic basis
Dual Titration
1. Both H2O2 and PAA are measured by two different titrants.
1. First H2O2 titrated with ceric sulfate
2. Ferroin used as the indicator
3. Endpoint color transition is salmon to blue
H2O2 + 2 Ce(SO4)2 → Ce2(SO4)3 +H2SO4 + O2
4. Excess of potassium iodide added to sample
5. PAA liberates iodine
6. Iodine is titrated against sodium thiosulfate
7. Starch used as the indicator
8. Endpoint color is the absence of purple
2 KI + H2SO4 → 2 HI + K2SO4 CH3 C O OOH CH3 C O OH + 2HI I + H2O
• DPD (N, N-diethyl-p-phenylenediamine) and potassium iodide
• Same colorimetric method used to measure total chlorine
• PAA is treated with an excess of potassium iodide and oxidizes it to
iodine.
• Iodine subsequently oxidizes DPD to a pink color in direct proportion
to the [PAA].
• Visual and instrumental PAA test kits are available.
• Pre-calibrated photometers are available.
• A blank measurement using a sample w/o PAA treatment will help
to reduce impact from wastewater background color, turbidity or
other constituents.
DPD, continued
Elimination of PAA Interference
• State regulators may be interested in monitoring H2O2 levels in final
effluent
• Although H2O2 does not interfere with the measurement of PAA, PAA
will interfere in the measurement of hydrogen peroxide.
• CHEMetrics H2O2 test kits utilize the ferric thiocyanate method
whereby H2O2 oxidizes ferrous iron to ferric iron which then forms an
orange color complex with the thiocyanate ion.
• By pre-treating the sample with a solution of potassium iodide the
PAA interference is neutralized. Iodine does not interfere with the
method.
• PAA disinfection has several advantages over chlorine
disinfection
• Full scale installations are in place across the US and
Canada
• State regulatory environmental agencies are seeking
guidance from EPA
• A new WERF research proposal to study various aspects
of PAA disinfection will be awarded this year
• Routine PAA monitoring can be accomplished easily and
quickly