Selenium Removal from Mine Waters
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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

Morgantown, WV


Support

National Mine Land Reclamation Center, West Virginia University

United States Office of Surface Mining

Magnum Coal Company

Catenary Coal

SUPPORT


Typical southern west virginia mine water

[Se] = 13 ug/L University

[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
Problems University

  • 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
Selenium Removal Difficulties University

  • Different dissolved species

  • No direct precipitation chemistries

  • Reduction of selenate is difficult (slow)

  • Sulfate may interfere


Treatment system objectives
Treatment System Objectives University

  • Effluent maximally 5 ug/L Se

  • Low installation cost

  • Low operating cost

  • Passive


Demonstrated chemistries
Demonstrated Chemistries University

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

  • Biological (bacterial reduction)

  • Reverse osmosis

  • Reduction by Fe(0)


Reduction with iron metal
Reduction with Iron Metal University

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

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



Field trial catenary coal
Field Trial UniversityCatenary Coal

Test in a real setting

Real, variable input chemistry

Continuous Se Input


Field trial system
Field Trial System University


Field trial system1
Field Trial System University


Catenary post trial 1
Catenary University Post Trial 1


Catenary post trial 2
Catenary University Post Trial 2


Catenary post trial 3
Catenary University Post Trial 3


Catenary post trial 4
Catenary University Post Trial 4


Catenary post trial 5
Catenary University Post Trial 5


Reduction with iron metal1
Reduction with Iron Metal University

  • Potential

    • Removal of selenate and selenite

    • Passive

  • Problems

    • Iron Oxides/ Dissolved Fe, Mn

    • Exhaustion

    • Passivation

    • Expense (surface area)


Bacterial estimated cost
Bacterial UniversityEstimated Cost

  • Flow = 285 gpm

  • Capital Cost = $7.2 to $10 million

  • O&M = Unknown


Reverse osmosis estimated cost
Reverse Osmosis UniversityEstimated Cost

  • Flow = 200 gpm

  • Capital Costs = $1.2 million

  • O&M = $5.85 million/year


Iron hydroxide estimated cost
Iron Hydroxide UniversityEstimated Cost

  • Flow = 200 gpm

  • Capital Cost = $0.69 to 1.03 million

  • O&M = $1.39 million/year


Zerovalent iron estimated cost
Zerovalent Iron UniversityEstimated Cost

  • Flow = 250 gpm*

  • Capital costs = $478,000

  • O&M = $150,000 to $300,000

    * Gravity flow, includes surge


Conclusions
Conclusions University

  • 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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