Alissa J. O’DonnellUniversity of Cincinnati, Dec 2014M.S. Environmental Engineering

Cincinnati, OH 45219

One Water Ohio ConferenceAugust 26-19, 2014 | Columbus, OH

Conventional Drinking Water Treatments on Strontium

Reduction

Darren A. LytleU.S. Environmental Protection Agency

ORD, NRMRL, WSWRD, TTEBCincinnati, OH 45268

Elemental Properties Naturally occurring alkaline earth metal Behaves very similar to calcium

Manufacturing Making of pyrotechnics, alloys, ceramics, and glass Block x-ray emissions from cathode-ray tubes

Locations Found Widely distributed in the earth’s crust and ocean Majority of strontium compounds dissolve in water

Exposure Drinking water Food

Grains, leafy vegetables, dairy products are the largest contributor to dietary strontium.

Stable Strontium (Sr)

Health Effects(1992 EPA IRIS - Risk Assessment)

Image source: aurorahealthcare.org/yourhealth/healthgate/images/exh4511a.jpg

Limited studies

No indication of tumorigeniceffects

High levels effect infants, children, and adolescents

Substitutes for calcium during bone calcification or displaces calcium from existing calcified matrix

Abnormal skeletal development (rickets)

Exacerbated by inadequate calcium levels

Contaminant Candidate List 3• Sept 2013, AWWA source considered chlorate,

nitrosomines, and stronium most likely to be regulated• Stable Strontium (CAS : 7440-24-6)• Health Reference Level = 4.0 mg/L

Unregulated Contaminant Monitoring Rule 3• Requires systems to conduct four quarters of monitoring

between January 2013 and December 2015• 0.3 µg/L minimum reporting level for strontium

Regulatory Relevance

Occurrence in U.S. Ground Waters(USGS NWIS & EPA STORET)

Distribution in Ground Waters(USGS NWIS & EPA STORET)

Occurrence and Distributionin U.S. Surface Waters(USGS NWIS & EPA STORET)

Current Treatments

Drinking Water To the best of our knowledge, there is no existing

information.

Industrial Wastewater Adsorption Ion exchange Biological treatment

Radioactive Isotope, Strontium-90 Regulated since 1977 Most prevalent radioactive isotope

Sorption Nanofiltration Biological Treatment

Evaluate the removal of strontium from groundwaters in full-scale plants• EPA studies• Lime softening, cation exchange softening, adsorption

media, and iron removal• Point-of-Entry and Point-of-Use treatments

Perform bench-scale studies to evaluate the impact of coagulation and softening on strontium removal• Jar testing• Impact of coagulant, pH, NTU, lime dose, and initial

strontium concentration

Solubility Studies• Impact of pH, DIC, and calcium

Objective

EPA WSWRD Studies

*Gray filled rows with bold font designate raw values above current health guidelines (4ppm)

Full-Scale Treatments

State Raw Finished SrontiumRemoved Treatment Type

OH 36.3 0.04 99.9% Cation Exchange SofteningIL 0.27 0.00 98.9% Cation Exchange SofteningIL 0.34 0.02 92.7% Cation Exchange SofteningIL 0.57 0.06 89.3% Cation Exchange Softening

OH 3.42 0.91 73.5% Lime SofteningIL 0.48 0.32 33.3% Cation Exchange SofteningIL 0.54 0.48 11.3% Granular Media FiltrationIN 10.9 10.4 4.0% ADI G2 Media AdsorptionOH 1.81 1.77 2.4% Sand FiltrationIL 0.62 0.60 2.0% Anthracite over GreensandPlus FiltrationPA 0.25 0.25 1.2% AdEdge GS+ Media FiltrationMI 1.11 1.13 0.0% Granular Media FiltrationIL 0.36 0.53 0.0% AdEdge Bayoxide®E33 Media AdsorptionIL 0.33 0.43 0.0% Anthracite over Gravel Filtration

The Village of Versailles, Ohio(Lime Softening)

9 Wells

1.5 mgd max. capacity

Forced draft aerator

Solid contact clarifier

Lime & Soda Ash addition• Lime: 525-575 mg/L• Soda Ash: 125-145 mg/L• CO2: 344-1032 lbs/day

Four-cell rapid sand filter unitDate Collected

Apr May Jun Jul Aug Sep Oct Nov

Stro

ntiu

m (m

g/L

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Raw AeratedPost ClarifierFinalAverage Raw (3.51)Average Finished (0.94)

Point-of-Entry and Point-of-Use TreatmentsState Raw Finished Srontium

Removed Treatment Type

ID 0.46 0.00 100% Cation Exchange SofteningIA 0.36 0.00 100% Cation Exchange SofteningOH 8.22 0.01 99.9% Cation Exchange SofteningMI 0.92 0.00 99.9% **RO Watts Premier WP-4VMI 0.99 0.00 99.8% **RO Watts Premier M-2400MI 0.85 0.00 99.8% **RO Pall-Kinetico PurefectaIL 0.27 0.00 98.7% Cation Exchange Softening

OH 1.31 0.03 98.0% Cation Exchange SofteningMI 0.96 0.03 96.6% **RO EcoWater Systems ERO-R450EOH 0.84 0.03 96.4% Cation Exchange SofteningOH 3.11 0.12 96.3% Cation Exchange SofteningIL 0.26 0.04 85.8% Reverse Osmosis

OH 9.55 4.36 54.3% Cation Exchange SofteningOH 0.10 0.07 35.4% Reverse OsmosisOH 0.03 0.10 0.00% GFH Media Adsorption*Gray filled rows with bold font designate raw values above current health guidelines (4ppm)** EPA Environmental Technical Verification Program

Jar Testing Conditions: CoagulationType Chemical Addition Dosing Sr Add pH Turbidity Varied Conditions

Surface Alum varied 5 7.7 - 0, 10, 20, 30, 40, 50

Surface FeCl3 varied 5 7.7 - 0, 10, 20, 30, 40, 50

Surface Alum + Strontium optimum varied 7.7 - 1, 2.5, 4, 6, 8, 10

Surface FeCl3 + Strontium optimum varied 7.7 - 1, 2.5, 4, 6, 8, 10

Surface Alum optimum 5 varied - 6.0, 7.0, 8.0, 9.0

Surface FeCl3 optimum 5 varied - 6.0, 7.0, 8.0, 9.0

Surface Alum optimum 5 7.7 varied 25, 50, 75, 100, 125

Surface FeCl3 optimum 5 7.7 varied 25, 50, 75, 100, 125

Raw Alum Ferric ChlorideSurface Water 30mg/L 30 mg/L

Raw Alum Ferric ChlorideSurface Water 30mg/L 30 mg/L

Initial Mixing

After Settling

Alum – 0.2µm Filtration

FeCl3 – 0.2µm Filtration

Coagulation

ChemicalCoagulant Sample Dose

(mg/L)pH

(pH unit)DO

(mg/L)Temp(°C)

Color(PtCo)

Turbidity(NTU)

Strontium(mg/L)

% Strontium Removed

FerricChloride

Initial 0 7.78 9.09 20.0 190 43 4.98 1.75%Final 7.66 9.10 20.0 74 8 4.89Initial 10 7.71 9.10 20.0 211 42 4.72 0.00%Final 7.72 8.96 21.1 5 2 4.76Initial 20 7.75 9.14 20.0 257 43 4.69 2.41%Final 7.73 8.95 21.1 41 5 4.57Initial 30 7.68 9.29 19.9 253 29 4.76 1.05%Final 7.73 9.03 20.7 36 7 4.71Initial 40 7.75 9.13 20.0 325 39 4.67 1.44%Final 7.63 8.94 20.9 31 2 4.60Initial 50 7.77 9.14 20.0 399 41 4.61 2.71%Final 7.65 8.93 20.9 7 1 4.49

ChemicalCoagulant Sample Dose

(mg/L)pH

(pH unit)DO

(mg/L)Temp(°C)

Color(PtCo)

Turbidity(NTU)

Strontium(mg/L)

% Strontium Removed

Alum

Initial 0 6.86 10.26 19.1 113 20 4.98 1.16%Final 7.11 9.50 20.4 66 5 4.93Initial 10 6.91 9.98 19.4 121 22 4.89 0.00%Final 7.07 9.37 20.4 26 2 4.90Initial 20 6.82 9.93 19.5 124 21 4.93 0.60%Final 6.95 9.33 20.5 22 2 4.90Initial 30 7.11 9.63 19.5 132 18 4.78 0.00%Final 7.20 9.31 20.6 42 4 4.82Initial 40 6.58 9.68 19.6 118 22 4.83 0.00%Final 6.76 9.32 20.4 28 2 4.87Initial 50 6.44 9.73 19.4 136 21 4.84 0.00%Final 6.60 9.36 20.2 25 2 4.86

Coagulation

Jar Testing Conditions: Softening

Type Chemical Addition Dosing Sr pH Varied Conditions

Ground Ohio 1Lime + Soda Ash varied - 7.7 0, 25, 50, 75, 100

Ground Ohio 1Lime + Soda Ash varied - 7.7 125, 150, 175, 200, 250

Ground Ohio 1Lime + Soda Ash varied - 7.7 0, 50, 100, 150, 200

Ground Ohio 1Lime + Soda Ash varied - 7.7 250, 300, 350, 400, 450

Ground Ohio 2Lime + Soda Ash + Strontium varied 5 varied 0, 50, 100, 150, 200

Ground Ohio 2Lime + Soda Ash + Strontium varied 5 varied 250, 300, 350, 400, 450

Ground Ohio 2Lime + Soda Ash + Strontium optimum varied varied 1, 2.5, 4, 6, 8, 10

Initial Mixing

Settled

Increase of Lime Dosage --- >

Lime & Soda Ash - 0.2µm Filtration

Softening

SampleSoda Ash

Dose (mg/L)

Lime Dose

(mg/L)

pH(pH unit)

DO(mg/L)

Temp(°C)

Color(PtCo)

Turbidity(NTU)

Calcium(mg/L)

Strontium(mg/L)

Strontium Removed

Initial 45 0 7.74 8.90 22.9 51 15 99.6 3.64 0.56%Final 7.88 8.95 23.9 9 1 97.0 3.62Initial 45 50 7.75 8.77 23.1 276 115 106.4 3.49 11.39%Final 7.88 8.79 23.8 46 16 71.4 3.09Initial 45 100 7.69 8.88 22.9 542 236 135.8 3.51 29.26%Final 7.94 8.93 23.9 37 11 63.8 2.48Initial 45 150 7.70 8.78 23.1 600 394 143.4 3.32 46.31%Final 8.23 8.79 23.8 64 16 45.3 1.78Initial 45 200 7.72 8.87 22.9 600 445 173.7 3.38 44.92%Final 8.16 8.90 24.0 97 31 66.6 1.86Initial 45 250 7.74 8.50 23.5 600 512 228.2 3.70 52.54%Final 7.95 8.67 24.3 7 5 68.9 1.76Initial 45 300 7.73 8.71 23.1 600 635 288.1 3.94 70.13%Final 8.33 8.90 24.1 10 3 53.0 1.18Initial 45 350 7.71 8.49 23.5 600 700 274.0 3.69 75.05%Final 8.61 8.68 24.3 3 2 37.7 0.92Initial 45 400 7.72 8.69 23.1 600 749 292.5 3.41 63.28%Final 8.36 8.84 24.1 11 4 68.5 1.25Initial 45 450 7.65 8.46 23.5 600 951 321.6 3.61 54.28%Final 7.93 8.79 24.3 10 4 101.2 1.65

Softening

pH

7.6 7.8 8.0 8.2 8.4 8.6 8.8 9.0

Cal

cium

(mg/

L)

0

20

40

60

80

100

120

pH

7.6 7.8 8.0 8.2 8.4 8.6 8.8 9.0

Stro

ntiu

m (m

g/L

)

0

1

2

3

4

5

Impact of pH on Calcium Strontium RemovalDuring Lime Softening

Fundamental Precipitation Experiments

TestStrontium

Concentration (mg/L)

CalciumConcentration

(mg/L)

DissolvedInorganicCarbon (mg/L)

pH

1 1.0 0 85 5-11

2 5.5 0 85 5-11

3 10.0 0 85 5-11

4 5.0 110 10 5-12

5 5.0 110 10 5-12

6 1.0 110 85 5-12

7 5.5 110 85 5-12

8 10.0 110 85 5-12

Conclusions Strontium is relatively widely distributed in ground water across

the US

Full-scale data showed that strontium can be effectively reduced by lime softening, cation exchange, POU/POE reverse osmosis

Full-scale data showed that iron removal and adsorption media (arsenic removal) did not effectively reduce strontium

Jar testing showed that strontium is effectively removed during lime/soda ash softening and removal was related to lime dose/pH/calcium

Strontium was not effectively removed during iron removal or coagulation jar testing

Additional jar testing and solubility results are coming

Acknowledgements Maily Pham and Keith Kelty, U.S. EPA

• Conducted analyses for AES and MS

Bill Kaylor, National Council on Aging SEE• Conducted analyses for Alk and Cl-

Water utility operators and staff• Village of Versailles• City of Cincinnati, Miller Treatment Plant• City of Cincinnati, Bolton Treatment Plant

Nicholas Dugan and Jonathan Pressman, U.S. EPA• Collection of water used for bench-scale testing

Christy Muhlen and Dan Williams, U.S. EPA• Ordered supplies needed• Packed and shipped coolers for water samples

Notice:

The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and

managed, or partially funded and collaborated in, the research described herein. It has been subjected to the Agency’s peer and administrative review and has been

approved for external publication. Any opinions expressed in this paper are those of the author (s) and do not

necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred. Any mention of trade names or commercial products does not constitute

endorsement or recommendation for use.