The Application and Measurement of Peracetic Acid for Wastewater Disinfection

Transcription

1 The Application and Measurement of Peracetic Acid for Wastewater Disinfection 2016 Good Laboratory Practices Conference Joanne Carpenter, CHEMetrics, Inc. Philip Block, Ph.D, PeroxyChem

2 Audience Survey Any audience members using PAA disinfection at their plants? Any audience members working at plants that have plans to study PAA disinfection?

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4 PAA Buzz

5 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

6 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 (H 2 O 2 ) 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

7 PAA Cons Requires local DEQ approval Does not maintain a residual Buried piping is not recommended to facilitate repairs if a leak should develop

8 PAA Electrochemical Oxidation Potential Ranking

9 PAA Applications Widely used in Europe for wastewater disinfection Tertiary disinfectant Combined Sewer Overflow (CSO) disinfectant In conjunction with UV disinfection Lagoon disinfectant

10 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

11 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 vol. 82, no. 4

12 PAA Chemical Properties Commercially available as an equilibrium mixture of: Peracetic acid 12-15% Hydrogen peroxide % Inert ingredients acetic acid ~18% water ~51% CH 3 CO 2 H + H 2 O 2 CH 3 CO 3 H + H 2 O Acetic Acid Hydrogen Peroxide PAA Water PAA, Peroxyacetic Acid, Ethaneperoxoic acid, Peroxide of Acetic Acid

13 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

14 PAA Vendors PeroxyChem, VigorOx WWT II Solvay, Proxitane EnviroTech, BioSide EcoLab (no products labeled for wastewater disinfection)

15 Source:

16 CDM Smith CH2M Hill MWH Global

17 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.

18 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.

19 VigorOx WWTII CDM Smith/PeroxyChem Evaluation of impact of water quality on PAA demand with time ph Suspended solids Organic matter Temperature

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21 M.C. Stiles wastewater treatment plant, Memphis, TN coarse and fine bar screening Disinfection Contact Tanks Final Clarifiers Final Clarifiers Contact Stabilization Tanks Screening & Grit Chambers contact stabilization process secondary clarification no current disinfection (contact channel is in place) discharge to river

22 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

23 large variation in water quality very low % UVT Daily Performance Data Parameter Minimum observed Average or mean 1 Maximum observed Daily Flow 2 (MGD) BOD 3 (mg/l) TSS 3 (mg/l) ph 4 (s.u.) E. coli 5 (cfu/100ml) 1.3 x 10 4 (4.4 x 10 5 as 1.1 x x 10 5 geomean) Apparent color 6 (PtCo units) True color 6 (PtCo units) Apparent UVT 6 (%) Filtered UVT 6 (%) Historical effluent water quality characteristics

24 Full scale 6 month 5 phase dose control demonstration trial Disinfection contact tank was split one side served as a control (no PAA treatment) BFM E Coli Effluent PAA Probe 3 PAA treated side PAA Probe 2 E Coli Mid PAA Probe 1 PAA Dose point Effluent E Coli Influent Color UVT ph / temp COD Influent Untreated side

25 Phase 1 Conducted over 2 week period PAA flow paced Continuous monitoring using on-line analyzers Color ORP % 254 nm ph Temperature COD Grab Samples - E. Coli counts and COD (used to calibrate COD sensor) PAA influent and effluent Each parameter was correlated with PAA demand Dosing algorithm was developed for each parameter

26 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

27 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

28 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

29 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 ppm Influent E. coli concentrations > 1.2 x 10 6 cfu/100 ml measured Daily sampling

30 Phase 5 Results All samples measured < daily maximum (487 cfu/100 ml) One sample exceeded monthly geometric mean 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

31 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

32 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?

33 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).

34 PAA Measurement Techniques 1. In-situ probes (ppm to %) 2. Ceric Sulfate/Iodometric (dual) titration (%) 3. DPD colorimetric method (ppm) (EPA Method or Standard Methods 4500 Cl2)

35 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

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37 Dual Titration 1. Both H 2 O 2 and PAA are measured by two different titrants. 1. First H 2 O 2 titrated with ceric sulfate 2. Ferroin used as the indicator 3. Endpoint color transition is salmon to blue H 2 O Ce(SO 4 ) 2 Ce 2 (SO 4 ) 3 +H 2 SO 4 + O 2 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

38 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.

39 DPD, continued

40 Elimination of PAA Interference State regulators may be interested in monitoring H 2 O 2 levels in final effluent Although H 2 O 2 does not interfere with the measurement of PAA, PAA will interfere in the measurement of hydrogen peroxide. CHEMetrics H 2 O 2 test kits utilize the ferric thiocyanate method whereby H 2 O 2 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.

41 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