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Raw Water Quality Not Textbook? Just Pilot! Iron Removal with High pH Raw Water March 27, 2008

Raw Water Quality Not Textbook? Just Pilot! Iron Removal with High pH Raw Water March 27, 2008. Sandy Kutzing, P.E., CDM Eric Hahn, P.E., NJAW. Today’s Presentation. Background Treatment Alternatives Oxidation and Filtration Fe and Water Chemistry Pilot Test Design.

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Raw Water Quality Not Textbook? Just Pilot! Iron Removal with High pH Raw Water March 27, 2008

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  1. Raw Water Quality Not Textbook? Just Pilot!Iron Removal with HighpH Raw Water March 27, 2008 Sandy Kutzing, P.E., CDM Eric Hahn, P.E., NJAW

  2. Today’s Presentation • Background • Treatment Alternatives • Oxidation and Filtration • Fe and Water Chemistry • Pilot Test • Design

  3. New Jersey American Water • Serves more than 2 million people in 180 communities • 623,800 connections • 8,100 miles (12 000 km) of main from 2” to 72” (5 to 183 cm) in size • 170,000 valves, including hydrant branch valves CurrentOperations New Jersey American Water

  4. Background Monterey Beach, NJ • Existing well – PRM • Allocation limit of 900 GPM • SOS is limited on Barrier Island • Location • Large seasonal demand fluctuation

  5. Project Location

  6. Problem / Water Quality • Current Treatment • Sequestration • Customer Issues • Discoloration of laundry • Staining of sink • Taste and Odor

  7. Iron Levels • Iron Requirement • NJDEP Secondary Contaminant – Recommended Upper Limit = 0.3 (mg/L) • With Sequestration Treatment – Recommended Upper Limit = 0.6 (mg/L) • When Upper limit is exceeded, Treatment must be added to reduce levels below 0.3 mg/L

  8. Treatment Alternatives • Evaluated treatment methods • Membranes – eliminated due to space limitations and cost • Biological removal – eliminated due to increase in O&M • Oxidation with filtration – treatment method of choice

  9. Oxidation with Filtration • Basics of treatment process • Oxidation of iron and manganese with the addition of chlorine • Dual media filtration of precipitates • Manganese dioxide coating on sand acts as catalyst for oxidation and reduction of iron and manganese

  10. GreensandPlus Technology • Selected in previous study • GreensandPlus media • Silica sand • Manganese dioxide coating • Ordinary Manganese Greensand versus GreensandPlus

  11. GREENSAND+

  12. Existing Operations Chemical Injection 2. Tank (300K gal) 1. Well Head 3. Booster Station 4. Discharge to Distribution System

  13. Location Details NJAW Monterey Well Site NJAW Vacant Lot

  14. Proposed Site

  15. Proposed Operations Chemical Injection 2. GreensandPlus Filters 3. Tank (300K gal) Prechlorination 1. Well Head 4. Booster Station 5. Discharge to Distribution System

  16. Iron and Water Chemistry • Surface Water Iron • Oxidized form as precipitate • Typically removed by conventional clarification • Groundwater Iron • Deprived of Oxygen • Reduced Form (2+) and in solution

  17. From “Water Treatment Handbook”, Degremont, 1979

  18. Oxidation and Filtration • Most widely used treatment • Manganese Dioxide (MnO2) or green sand • Oxidizes iron (II) and Manganese • Precipitated and retained by the filter media • Prechlorination oxidizes iron at Monterey Beach

  19. Abnormal Water Quality and Filtration • Effectiveness varies with pH and oxidation-reduction potential (EH2) • Monterey, NJ Well • Possibly collodial or complex iron • High pH (above 7.5) • Iron Fe2+ (dissolved) most likely but not a guarantee

  20. Iron: pH and Oxidation-Reduction Potential Potential (Volts) pH

  21. Bench Scale Test • Prechlorinate to oxidize iron • Filter • Test for removal of Iron • Confirm: Iron form likely Fe2+

  22. Pilot Test • Higher Loading Rates • 5 to 7 gpm/ft2 • Confirm Iron and Manganese Removal • Prechlorinate • Impact of MnO2 coated green sands

  23. Pilot Study

  24. Pilot Study Results • Effluent Iron concentrations • 0.05 mg/L • Effluent Manganese concentrations • 0.02 mg/L • Headloss

  25. Raw, 5 gpm/sf Raw, 7 gpm/sf Effluent, 5 gpm/sf NJDEP Secondary Contaminant Level Effluent, 7 gpm/sf NJAW Performance Requirement Pilot Study Results 0.9 0.8 0.7 0.6 0.5 0.4 Iron (mg/L) 0.3 0.2 0.1 0 0 10 20 30 40 50 60 70 Filter Run Time (Hours)

  26. Pilot Study Frequency Effluent Iron Concentration

  27. Design • GreensandPlus filters • Regular operation • Backwash operation (one filter backwashing) • Benefits of higher loading rate • Recycle 85% backwash flow

  28. Recap • Background • Treatment Alternatives • Oxidation and Filtration • Fe and Water Chemistry • Bench Scale & Pilot Tests • Design Questions?

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