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In Situ Treatment with hydrogen Peroxide. Bruce Leavitt PE PG, Consulting Hydrogeologist Washington, Pennsylvania. Prepared in conjunction with West Virginia University under a grant from the Office of Surface Mining Applied Science Research Program. Hydrogen Peroxide:
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In Situ Treatment with hydrogen Peroxide Bruce Leavitt PE PG, Consulting Hydrogeologist Washington, Pennsylvania Prepared in conjunction with West Virginia University under a grant from the Office of Surface Mining Applied Science Research Program
Hydrogen Peroxide: • Net alkaline mine drainage • Rapidly oxidize ferrous iron in mine drainage • 2 Fe2+ + H2O2 + 4 OH¯ → 2 Fe(OH)3 • Is used at some AMD treatment facilities. • Freezing point -33 C° (35 % solution) • Density 1.132 (35 % solution)
Date Time pH DO ORP Alk 8/18/2009 10:50 6.55 0.05 -69 116 Peroxide on 8/18/09 11:10 35% @10% metering pump 8/19/2009 8:50 5.93 5.83 250 62 Effect of Peroxide Addition
Bench Tests 10 liter continuously stirred Dilute 35% H202 to 11.67% Monitor pH, ORP, & DO Micro pipette (0.02357 g/dose) Aeration tests with and without peroxide Settling tests
Settling of Peroxide Treated Mine Water 24 hours 50 min. 100 min.
Travel Time Ruthbelle to main discharge 32 hours at 700 to 750 gpm, Coastal Coal dye test. Coastal well to sampling well: 87 minutes first arrival, 212 minutes complete reaction.
Flow in the Mine Entry Mine Discharge 175 gpm. Calculated flow in the test entry 43 gpm. Calculated flow is 24.6% of total flow. Mined area is about 33% of total mined area. Flow unlikely in up dip entry. Possibilities: Non-uniform recharge, Sludge disposal, Flow in up dip entry.
Cost of Treatment 43 gpm @ 33.45 mg/L Ferrous required 6.2 to 6.32 mL/min of 35% H2O2. 146.5 mL / 1000 gal. 600 gal H2O2 = $3,400 $0.22 per 1000 gal treated. $0.0066 per mg/L/1000 gal.
Conclusions In Situ oxidation of ferrous iron using hydrogen peroxide has been demonstrated. The reaction is rapid and proportional to dose. Either pH, ORP, or both may be used to determine the completion of the oxidation process so that over treatment does not occur. Hydrogen Peroxide addition does not affect the amount of carbon dioxide dissolved in the mine water.
Conclusions continued Hydrogen peroxide can be used to determine the volume of flow in an entry. Injection of hydrogen peroxide into a point of concentrated flow was deemed essential. The chemical cost of Hydrogen Peroxide treatment has been calculated to be $0.0066 per mg/l ferrous per 1000 gallons. The estimated capital cost for a single site is $36,000 although this number will vary with site specific conditions.
Recomendations The potential addition of alkalinity to the sludge disposal water in T&T #3 should be investigated. In Situ settlement of iron should be achievable in T&T #2 if the location of the injection well is located further in-by the test location. Pre-aeration may reduce ammonia requirement.