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American Water 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.,

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Presentation on theme: "American Water 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.,"— Presentation transcript:

1 American Water 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

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

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

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

5 American Water Project Location

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

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

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

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

10 American Water GreensandPlus Technology u Selected in previous study u GreensandPlus media u Silica sand u Manganese dioxide coating u Ordinary Manganese Greensand versus GreensandPlus

11 American Water GREENSAND+

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

13 American Water Location Details NJAW Monterey Well Site NJAW Vacant Lot

14 American Water Proposed Site

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

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

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

18 American Water Oxidation and Filtration u Most widely used treatment u Manganese Dioxide (MnO 2 ) or green sand u Oxidizes iron (II) and Manganese u Precipitated and retained by the filter media u Prechlorination oxidizes iron at Monterey Beach

19 American Water Abnormal Water Quality and Filtration u Effectiveness varies with pH and oxidation-reduction potential (E H 2 ) u Monterey, NJ Well u Possibly collodial or complex iron u High pH (above 7.5) –Iron Fe 2+ (dissolved) most likely but not a guarantee

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

21 American Water

22 Bench Scale Test u Prechlorinate to oxidize iron u Filter u Test for removal of Iron u Confirm: Iron form likely Fe 2+

23 American Water Pilot Test u Higher Loading Rates u 5 to 7 gpm/ft 2 u Confirm Iron and Manganese Removal u Prechlorinate u Impact of MnO 2 coated green sands

24 American Water Pilot Study

25 American Water Pilot Study Results u Effluent Iron concentrations u 0.05 mg/L u Effluent Manganese concentrations u 0.02 mg/L u Headloss

26 American Water Pilot Study Results Iron (mg/L) Filter Run Time (Hours) Raw, 5 gpm/sf Raw, 7 gpm/sf Effluent, 5 gpm/sf Effluent, 7 gpm/sf NJDEP Secondary Contaminant Level NJAW Performance Requirement

27 American Water Pilot Study Frequency Effluent Iron Concentration

28 American WaterDesign u GreensandPlus filters u Regular operation u Backwash operation (one filter backwashing) u Benefits of higher loading rate u Recycle 85% backwash flow

29 American WaterRecap u Background u Treatment Alternatives u Oxidation and Filtration u Fe and Water Chemistry u Bench Scale & Pilot Tests u Design Questions?


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