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

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 4 th 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 Filters Deep Bed Filters Disinfection & Dechlorination Reuse 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: % 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 ChlorineFull Flow Remove Precursor OzoneGAC/PACMIEX Replace Chlorine OzonePAAImprove UVTOzone/UVPAA/UVGAC/PAC/UVFerrate/UVMIEX//UVRemove DBPsGAC/PACAerationOther Split 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 ConfigurationAlternatives 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 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

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 PAA ComponentConcentration (% by wt) Peracetic Acid12 Hydrogen Peroxide18.5 Acetic Acid15

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 Date PAA Dose, mg/L DT, min.Inf./Eff. BDCM μg/L TTHM μg/L T HAA μg/L Bromate μg/L 26-Jul3.54Influent U 26-Jul3.54Effluent U 27-Jul3.07Influent U 27-Jul3.07Effluent 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 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

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

Results of Pilot Testing Peracetic Acid (PAA) –Effective dosages min 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

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!