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