1. Effective Use Of Peracetic Acid to Reduce Effluent Disinfection Byproduct in Water Resource Recovery Facilities Isaiah Shapiro, EIT Dimitri Katehis PhD, PE Dave Hagan, PE

2. Outline Background and Problem Identification Evaluation Approach Bench and Pilot Scale Testing Conclusion

3. Outline Background and Problem Identification Evaluation Approach Bench and Pilot Scale Testing Conclusion

4. City of Largo Located in Pinellas County 4 th largest City in Tampa Bay Serves about 75,000 residents

5. 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 Filters Deep Bed Filters Disinfection & Dechlorination Reuse or SWD

6. 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

7. Effluent BCDM Limits

8. Outline Background and Problem Identification Evaluation Approach Bench and Pilot Scale Testing Conclusion

9. 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

10. 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 ($$$)

11. 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

12. Split Flow Treatment

13. Many Options ChlorineFull Flow Remove Precursor OzoneGAC/PACMIEX Replace Chlorine OzonePAAImprove UVTOzone/UVPAA/UVGAC/PAC/UVFerrate/UVMIEX//UVRemove DBPsGAC/PACAerationOther Split Flow Same 31 Alternatives Evaluated

14. Outline Background and Problem Identification Evaluation Approach Bench and Pilot Scale Testing Conclusion

15. Preliminary Evaluation Technology Disinfection Precursor Removal BDCM Removal Bench Scale Testing Ozone Hydrogen Peroxide MIEX PAC/GAC Ferrate PAA Desktop Studies Coagulation Aeration

16. Viable Alternatives ConfigurationAlternatives Full Flow Treatment (FT)Ozone Split Flow Treatment (ST) Ozone + NaOCl PAA + NaOCl UV (48% UVT) + NaOCl

17. Non-Cost Criteria Analysis

18. Viable Alternatives - Costs 5% Interest, 20 Years ConfigurationAlternativesPW - 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

19. 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

20. Pilot Testing – UV and Ozone UVT Response to Applied Ozone Dose

21. PAA Pilot Testing 18,000-gallon Baffled Contact Tank Solvay Proxitane® WW-12 PAA ComponentConcentration (% by wt) Peracetic Acid12 Hydrogen Peroxide18.5 Acetic Acid15

22. 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

23. PAA Pilot Testing Date PAA Dose, mg/L DT, min.Inf./Eff. BDCM μg/L TTHM μg/L T HAA μg/L Bromate μg/L 26-Jul3.54Influent4.1204.65.0U 26-Jul3.54Effluent3.9197.35.0U 27-Jul3.07Influent4.8203.95.0U 27-Jul3.07Effluent4.2186.85.0U Results

24. 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 Samples 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

25. What happens when NaOCl and PAA mix? Solution No.SampleDose (mg/L) 15-min. Residual (mg/L) BDCM (µg/L) -Filtered effluent001.9 1Filtered effluent2.5 PAA1.0 PAA1.6 2Filtered effluent3.5 PAA1.3 PAA1.6 3Filtered effluent12 -Cl22.2 Cl214 4Filtered effluent9 - Cl21.3 Cl215 1 & 3BlendNA0.027.7 1 & 4BlendNA0.016.7 2 & 3BlendNA0.017.1 2 & 4BlendNA0.026.8

26. 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

27. Outline Background and Problem Identification Evaluation Approach Bench and Pilot Scale Testing Conclusion

28. PAA can be a cost-effective high level disinfection alternative to reduce disinfection by-products Split treatment option provides: –Reliability –Flexibility –Cost Control

29. Where are we today? Operations Permit Modification (2014) Final Design (2014) Award May 2015 ($13.7 M)

30. 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

31. Thank You!