effective use of peracetic acid to reduce effluent disinfection byproduct in water resource recovery...
TRANSCRIPT
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!