Selenium Removal from Mine Waters
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Selenium Removal from Mine Waters Raymond J. Lovett, Ph.D. Environmental Chemist ShipShaper, LLP PowerPoint PPT Presentation


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Selenium Removal from Mine Waters Raymond J. Lovett, Ph.D. Environmental Chemist ShipShaper, LLP Morgantown, WV. National Mine Land Reclamation Center, West Virginia University United States Office of Surface Mining Magnum Coal Company Catenary Coal. SUPPORT. [Se] = 13 ug/L

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Selenium Removal from Mine Waters Raymond J. Lovett, Ph.D. Environmental Chemist ShipShaper, LLP

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Selenium Removal from Mine Waters

Raymond J. Lovett, Ph.D.

Environmental Chemist

ShipShaper, LLP

Morgantown, WV


National Mine Land Reclamation Center, West Virginia University

United States Office of Surface Mining

Magnum Coal Company

Catenary Coal

SUPPORT


[Se] = 13 ug/L

[Fe] = 0.15 mg/L

[SO4-2]= 980 mg/L

Alkalinity = 235 mg/L as CaCO3

pH = 7.1

Typical Southern West Virginia Mine Water


Problems

  • Overriding Concern

    • Regulatory limit near 5 ug/L

  • Specific Problems for Treatment

    • Low level of Se

    • Differing chemistries

      • Selenate, SeO4-2, Se(VI)

      • Selenite, SeO3-2, Se(IV)


Selenium Removal Difficulties

  • Different dissolved species

  • No direct precipitation chemistries

  • Reduction of selenate is difficult (slow)

  • Sulfate may interfere


Treatment System Objectives

  • Effluent maximally 5 ug/L Se

  • Low installation cost

  • Low operating cost

  • Passive


Demonstrated Chemistries

  • Adsorption or co-precipitation by Fe(III) hydroxides

  • Biological (bacterial reduction)

  • Reverse osmosis

  • Reduction by Fe(0)


Reduction with Iron Metal

  • SeO4-2 +Fe(0) => Fe(II,III) +Se(0)

  • SeO3-2 +Fe(0) => Fe(II,III) +Se(0)


Selenium Species on Iron


Field TrialCatenary Coal

Test in a real setting

Real, variable input chemistry

Continuous Se Input


Field Trial System


Field Trial System


Catenary Post Trial 1


Catenary Post Trial 2


Catenary Post Trial 3


Catenary Post Trial 4


Catenary Post Trial 5


Reduction with Iron Metal

  • Potential

    • Removal of selenate and selenite

    • Passive

  • Problems

    • Iron Oxides/ Dissolved Fe, Mn

    • Exhaustion

    • Passivation

    • Expense (surface area)


BacterialEstimated Cost

  • Flow = 285 gpm

  • Capital Cost = $7.2 to $10 million

  • O&M = Unknown


Reverse OsmosisEstimated Cost

  • Flow = 200 gpm

  • Capital Costs = $1.2 million

  • O&M = $5.85 million/year


Iron HydroxideEstimated Cost

  • Flow = 200 gpm

  • Capital Cost = $0.69 to 1.03 million

  • O&M = $1.39 million/year


Zerovalent IronEstimated Cost

  • Flow = 250 gpm*

  • Capital costs = $478,000

  • O&M = $150,000 to $300,000

    * Gravity flow, includes surge


Conclusions

  • Iron metal removes selenate and selenite, but currently requires long contact times

  • Manganese and iron generated

  • Temperature sensitive (?)

  • Less expensive than other methods


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