Effective Use Of Peracetic Acid to Reduce Effluent Disinfection Byproduct in Water Resource Recovery FacilitiesIsaiah Shapiro, EITDimitri Katehis PhD, PEDave Hagan, PE

Outline

• Background and Problem

Identification

• Evaluation Approach

• Bench and Pilot Scale Testing

• Conclusion

Outline

• Background and Problem

Identification

• Evaluation Approach

• Bench and Pilot Scale Testing

• Conclusion

City of Largo

• Located in Pinellas County• 4th largest City in Tampa

Bay• Serves about 75,000

residents

WASTEWATER RECLAMATION FACILITY• Advance Wastewater Treatment Plant (AWTP)

– BOD:TSS:TN:TP = 5:5:3:1

• Influent Flow– Permitted: 18 MGD– Current: 12.5 MGD

• Effluent Discharge– Reuse: 50%– Surface Water Discharge: 50%

Headworks Primary Clarifiers A2O Process Secondary

Clarifiers

ABW FiltersDeep Bed Filters

Disinfection & DechlorinationReuse or SWD

Expanded Environmental Stewardship Goals

• Florida Department of Environmental Protection (FDEP)

• More stringent regulation of disinfection byproducts (DBPs) in the surface water discharge– bromo-dichloro-methane (BDCM)

• Existing Disinfection System– Chlorination with gaseous chlorine– Dechlorination with sulfur dioxide

Effluent BCDM Limits

Outline

• Background and Problem

Identification

• Evaluation Approach

• Bench and Pilot Scale Testing

• Conclusion

Evaluation Objective

• Reduce the effluent BDCM discharged to surface waters–Annual Average BCDM Limit• Interim: 30 μg/L• Final: 22 μg/L

• Provide an efficient and effective means of disinfection

Why not just UV?

• High Concentration of Dissolved Organics

• Very low UVT (38%)

• Low UVT mostly on wet weather flows

• Typical design UVT: 55-65%

• Double the cost ($$$)

Evaluation Approach

• Alternative Approaches:– Reduce Precursor (i.e. Dissolved

Organics)– Replace Gaseous Chlorine– Remove BCDM after it forms

• Treatment Configurations:– Full Flow Treatment– Split Flow Treatment

Split Flow Treatment

Many Options

Chlorine

Full Flow

Remove Precursor

Ozone

GAC/PAC

MIEX

Replace Chlorine

Ozone

PAA

Improve UVT

Ozone/UV

PAA/UV

GAC/PAC/UV

Ferrate/UV

MIEX//UV

Remove DBPs GAC/PAC

Aeration

OtherSplit Flow Same

• 31 Alternatives Evaluated

Outline

• Background and Problem

Identification

• Evaluation Approach

• Bench and Pilot Scale Testing

• Conclusion

Preliminary Evaluation

Technology Disinfection Precursor Removal

BDCM Removal

Bench Scale Testing

Ozone

Hydrogen Peroxide

MIEX

PAC/GAC

Ferrate

PAA

Desktop Studies

Coagulation

Aeration

Viable Alternatives

Configuration Alternatives

Full Flow Treatment (FT) Ozone

Split Flow Treatment (ST)

Ozone + NaOCl

PAA + NaOCl

UV (48% UVT) + NaOCl

Non-Cost Criteria Analysis

Viable Alternatives - Costs

5% Interest, 20 Years

Configuration Alternatives PW - 20% Present Worth PW + 35%

Full Flow Treatment (FT) Ozone $14.9M $16.7M $19.8M

Split Flow Treatment (ST)

Ozone + NaOCl $12.7M $14.2M $16.8M

PAA + NaOCl $11.7M $12.2M $13.1M

UV (48% UVT) + NaOCl $14.7M $16.1M $18.5M

Pilot Testing – UV and Ozone

• BCDM Reduction– Ozone was not able to

reduce BCDM below 22 μg/L• Dose up to 7 mg/L

• Precursor Removal:– Increase the filter

effluent UVT from 45% to 55%• Dose up to 10 mg/L

Advanced Oxidation Unit

Pilot Testing – UV and Ozone

• UVT Response to Applied Ozone Dose

PAA Pilot Testing

18,000-gallon Baffled Contact Tank

• Solvay Proxitane® WW-12 PAAComponent Concentration (% by wt)Peracetic Acid 12Hydrogen Peroxide 18.5Acetic Acid 15

PAA Pilot Testing

• Theoretical Detention Times– 15 min, 30 min & 45 min

• Dye Testing– Hydraulic Short Circuiting

• Actual Detention Times– 2 min, 4 min & 7 min

• Dosage Range:– 1.0 to 4.0 mg/L

PAA Pilot Testing

DatePAA

Dose, mg/L

DT, min. Inf./Eff. BDCMμg/L

TTHMμg/L

T HAAμg/L

Bromateμg/L

26-Jul 3.5 4 Influent 4.1 20 4.6 5.0 U

26-Jul 3.5 4 Effluent 3.9 19 7.3 5.0 U

27-Jul 3.0 7 Influent 4.8 20 3.9 5.0 U

27-Jul 3.0 7 Effluent 4.2 18 6.8 5.0 U

• Results

Follow Up Bench Scale Testing

Refining dose:• 2.5 mg/L to 3.5 mg/L• Actual contact time of 15 min to 30 min

Blend Sample

s

BDCM & Residual

PAA or Cl2

Sample Add Hypo Dose

Wait 15 min

BDCM & Residual Chlorine

Sample Add PAA Dose

Wait 15 min

BDCM & Residual

PAA

What happens when NaOCl and PAA mix?

Solution No. Sample Dose (mg/L) 15-min. Residual (mg/L) BDCM (µg/L)

- Filtered effluent 0 0 1.9

1 Filtered effluent 2.5 PAA 1.0 PAA 1.6

2 Filtered effluent 3.5 PAA 1.3 PAA 1.6

3 Filtered effluent 12 -Cl2 2.2 Cl2 14

4 Filtered effluent 9 - Cl2 1.3 Cl2 15

1 & 3 Blend NA 0.02 7.7

1 & 4 Blend NA 0.01 6.7

2 & 3 Blend NA 0.01 7.1

2 & 4 Blend NA 0.02 6.8

Results of Pilot Testing

• Peracetic Acid (PAA)– Effective dosages

• 3.0 mg/l @ 30 min• 3.5 mg/L @ 15 min

– Effective reduction of DBPs– No increase of toxicity (WET Testing)– Minor to no impact on BOD, Turbidity,

Conductivity or pH– Increases the DO of the effluent (1 to 5 mg/L)– Little need for quenching of PAA residual when

mixed with chlorine residual

Outline

• Background and Problem

Identification

• Evaluation Approach

• Bench and Pilot Scale Testing

• Conclusion

Conclusion

• PAA can be a cost-effective high level disinfection alternative to reduce disinfection by-products

• Split treatment option provides:–Reliability–Flexibility–Cost Control

Where are we today?

• Operations Permit Modification (2014)• Final Design (2014)• Award May 2015 ($13.7 M)

Acknowledgements

• Freddy Betancourt, PE, LEED AP, ENV SP – Greeley and Hansen

• David Hagan, PE – Greeley and Hansen• Leland Dicus, PE – City of Largo• Chuck Mura, PE – City of Largo• Our partners at CDM Smith

Special Thanks!• Bob Freeborn, Peragreen Solutions• John Maziuk, Solvay Chemicals

Thank You!