Is Oxygen Injection the Solution for Your Collection System Odors and Corrosion?

Transcription

1 Is Oxygen Injection the Solution for Your Collection System Odors and Corrosion? An Investigation into Current Applications and Industry Trends of Oxygen Injection for a Central Texas Municipality. Melissa K. Woo, PE Chelsea Solomon, PE August 6, 2015

2 Outline Background Odor Quantification Technology Screening Oxygen Injection Systems Considered Alternatives Evaluation and Design Considerations 2

3 Background

4 4 City of Georgetown

5 5 Sun City - Collection System

6 Sun City Collection System Odor Control Study Sun City Lift Station Year Average (mgd) Peak (mgd) Odor Issues Force main discharge Sinuso Dr. & Luna Trail Gravity line manholes Georgetown Airport Corrosion Impacts Gravity line manholes Existing Odor Control Chemical injection Calcium nitrate Cost concerns (Capacity)

7 Odor Quantification

8 Sampling Program Jan 7 Jan 15, 2015 Vapor Phase Analysis Hydrogen Sulfide (H 2 S) Week long monitoring Liquid Phase Analysis Dissolved Sulfide Biological Oxygen Demand (BOD) Temperature and ph Nitrate Addition One day at typical dose, 100 gpd OdaLog H 2 S Data Logger LaMotte Sulfide Test Kit 8

9 Sampling Locations Sun City Lift Station 9

10 Sampling Locations (cont.) Sinuso Dr. & Luna Trail Intersection 10

11 Sampling Locations (cont.) Georgetown Municipal Airport 11

12 Liquid Phase Analysis - Sampling Results Location Average ph Average Temp ( o F) BOD (mg/l) Sun City Lift Station Sinuso & Luna Manhole Georgetown Airport Manhole

13 Liquid Phase Analysis - Sampling Results Location Dissolved Sulfide Without Nitrate (mg/l) Dissolved Sulfide With Nitrate (mg/l) Average Peak Average Peak Sun City Lift Station <0.2 <0.2 <0.2 <0.2 Sinuso & Luna Manhole Georgetown Airport Manhole <0.2 <0.2 13

14 Vapor Phase Analysis - Sampling Results Location H 2 S Without Nitrate (ppm) H 2 S With Nitrate (ppm) Average Peak Average Peak Sun City Lift Station Sinuso & Luna Manhole Georgetown Airport Manhole Odor Control Target Sources Sinuso & Luna manhole Georgetown Airport 14

15 H2S (PPM) OdaLog H 2 S Results 400 Sun City Lift Station S&L Intersection Georgetown Airport /7/2015 1/8/2015 1/9/2015 1/10/2015 1/11/2015 1/12/2015 1/13/2015 1/14/2015 1/15/

16 Technology Screening

17 Technology Options Considered Technology Type Vapor Phase Treatment Liquid Phase Treatment - Chemical Liquid Phase Treatment - Oxygen Application Sinuso & Luna manhole Airport manhole(s) Lift station, for downstream control Lift station, for downstream control 17

18 Vapor Phase Treatment Technology Approach Treats odorous exhausts at source with hydroxyl radical fog system Oxidizes odorous compounds in air space instantly Advantages Proven, effective system technology at source location Beneficial annual and life cycle costs Disadvantage Limited application for collection system with multiple sources Hydroxyl Radical Fog System (Vapex) 18

19 19 Hydroxyl Radical Fog System - Vapex

20 Liquid Phase Treatment Technology - Chemical Approach Inject chemicals to prevent sulfide production Advantages Proven system technology Provides downstream control Low capital cost Disadvantages High annual and life cycle costs Requires chemical handling 20

21 Existing Odor Control System - Chemical Bioxide Calcium Nitrate Prevents biological sulfide formation Microbes prefer nitrate over sulfate for oxygen source Current System Dose approximately 100 gpd Sampling results Results suggest this dosage does not provide sufficient control Current cost: $2.22/gallon > $80,000 annually 21

22 Liquid Phase Treatment - Oxygen Injection Approach Inject oxygen to prevent sulfide production Advantages Proven technology Provides downstream control Beneficial annual and life cycle costs Disadvantages New systems Proprietary systems Requires oxygen generation 22

23 Oxygen Injection Technology Aerobic Conditions Prevent biological sulfide formation Development Strategy is not new Technological advances Increased efficiency Increased cost effectiveness Technology Pure oxygen injection Injection into force main; or Injection into sidestream flow Utilizes pressure head in force main to supersaturate oxygen into wastewater 23

24 Selected Technologies for Alternatives Evaluation Vapor Phase Treatment Liquid Phase Treatment Chemical Injection Liquid Phase Treatment Oxygen Injection 24

25 Oxygen Injection Systems Considered

26 Anue Ozone/Oxygen Injection Process Force main injection Ozone oxidation of odors Site control Oxygen aerobic conditions Downstream control Oxygen System Equipment Climate controlled building Air compressor and storage Oxygen generator and storage Oxygen booster pump Injection Vault Gas infusers 26

27 Anue Oxygen Injection Air Storage O 2 Storage Ambient Air O 2 Gas Air Compressor O 2 Generator Booster Pump Gas infusers Force Main 27

28 ECO 2 Oxygen Injection Process Sidestream flow pumped through oxygenation cone Super saturation mg/l Oxygenated sidestream blended back into force main System Equipment Sidestream pump Stainless steel oxygenation cone Oxygen source Oxygen generator Delivered liquid oxygen (LOX) 28

29 ECO 2 Oxygen Injection (cont.) Oxygen Supply ECO 2 SuperOxygenation Cone Booster Pump Lift Station Influent System Discharge Wet Well System Intake 29

30 BlueInGreen Oxygen Injection Process Sidestream flow pumped through oxygen transfer reactor Oxygenated sidestream blended back into force main System Equipment Skid-mounted system Sidestream pump Cylindrical oxygen transfer reactor Oxygen generator 30

31 Alternatives Evaluation and Design Considerations

32 Alternatives Alternative 1: Anue Oxygen Injection Alternative 2A: ECO 2 Oxygen Injection with Oxygen Generator Alternative 2B: ECO 2 Oxygen Injection with Delivered LOX Alternative 3: BlueinGreen Turnkey Oxygen Injection Alternative 4: Bioxide Chemical Injection: Improved Baseline: Bioxide Chemical Injection: Current 32

33 Oxygen Injection Technology Performance Criteria at Force Main Discharge Parameter Value Basis for Selection Wastewater Dissolved Sulfide Wastewater Dissolved Oxygen 0.5 mg/l 5.0 mg/l Typically lowest achievable sulfide level Lower concentrations can be cost prohibitive Ensure aerobic conditions at force main discharge Provide excess oxygen at force main discharge to carry downstream through airport 33

34 Oxygen Injection System Sizing Starting and target sulfide concentration Target oxygen concentration Microbial oxygen uptake rate Detention time in force main Flow rate Available system pressure 34

35 Alternatives Comparison Parameter Anue Oxygen Injection ECO 2 Oxygen Injection BlueInGreen Oxygen Injection Meets control objectives Yes Yes Yes Nitrate Injection Improved Dose Most Likely Nitrate Injection - Baseline No Procurement Purchase; or Leaseto-Own Purchase; or Leaseto-Own Purchase; or Lease-to- Own Lease Lease Pilot Available Yes (limited capacity) No Yes N/A N/A Note: Manufacturer information based on correspondence with manufacturers/representatives for this project; information subject to change. 35

36 Alternatives Comparison Parameter Oxygen Transfer Efficiency (Reported) Anue Oxygen Injection < 90% (depends on available pressure) ECO 2 Oxygen Injection BlueInGreen Oxygen Injection > 90% > 90% Oxygen Injection Location Force main Sidestream Sidestream Oxygen Dosage Control No. of Odor/ Corrosion Installations Years of Experience in Odor/ Corrosion Control Simple (manual) Complex (automatic: based on flow) Complex (automatic: based on flow, DO, or ORP) > 25 (one in TX) > 20 (two in TX) < 5 > 5 > 10 < 5 Note: Manufacturer information based on correspondence with manufacturers/representatives for this project; information subject to change. 36

37 Oxygen Injection Systems - Cost Considerations Capital Costs Oxygen injection equipment Buildings and vaults (if required) Oxygen generator and enclosures (if required) Sidestream piping and valves (if required) Gas piping and valves Civil improvements (roads, piping) Instrumentation and controls Electrical Site-specific permitting (if required) Annual Costs Electricity Operation and maintenance Liquid oxygen (if required) 37

38 Alternatives Preliminary Cost Assessment Parameter Capital Cost* Annual Cost 15-Yr Life Cycle Cost Oxygen Injection Systems with O 2 Generator $1.1 to $1.2M $11 to $16k $1.3 - $1.4M Oxygen Injection System with LOX $1.0M $20k $1.2 Nitrate Injection Improved Dose $0 > $120 $1.6M Nitrate Injection - Baseline $0 > $80 $1.0M *Includes construction, fees, and contingency costs 38

39 Evaluation Considerations Manufacturer Experience Newer technology Wastewater experience Repeat customers Proven System Effectiveness Oxygen transfer efficiency Installations, incl. in TX Effectiveness downstream of force main Sustainability Truckloads (chemical, bulk oxygen) vs. electricity consumption (oxygen generation) 39

40 Evaluation Considerations (cont.) Corrosion Reduction Oxygen vs. nitrate Future Use Transferability of system Transfer of capital Downstream Impact on Treatment Plant BOD reduction May impact Biological Nutrient Removal processes Supplemental carbon may be needed 40

41 Conclusion Report Recommendations Oxygen injection system Lower life cycle cost Ability to meet control objectives Current Project Status The City is reviewing report and recommendations 41

42 Closing Thoughts Oxygen Injection Viable alternative to vapor phase treatment and chemical injection Beneficial life cycle costs Evaluation and Design Considerations Define performance criteria Consider cost benefits, manufacturer experience, proven effectiveness, corrosion benefits, future use, downstream impacts, and sustainability 42

43 43 Questions?

44 Image References System photos courtesy of Anue, BlueinGreen, ECO 2, and Vapex Other photos: Georgetown_Texas.html