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ECONOX™
ECONOX™
Surface and deep shaft coal mining operations must meet EPA standards for the amount of acid, iron, and manganese in drainage waters. ECONOX™ is very effective for removing iron and manganese from acid rock drainage to meet discharge requirements.
- Insure metal discharge limits are routinely met
- Fast and efficient reactions
- Safe and easy to handle
- Do not form chlorinated organics which can find their way into drinking water
MANGANESE REMOVAL
Permanganate is a powerful oxidant that quickly reacts with soluble manganese to remove it in the form of insoluble manganese dioxide.
3Mn2+ + 2 MnO4
5 MnO2
It may seem a paradox that one manganese compound, permanganate, would be used successfully to produce a treated water that is free of manganese contamination. It is the oxidation potency of permanganate that established its use to remove manganese from water and wastewater. Permanganate treatment of manganese is commonly practiced in the water treatment industry, world-wide.
PERMANGANATE EVALUATIONS
Evaluating permanganate for the treatment of acid rock drainage requires the following steps:
Begin by collecting one or two gallons of the acid rock drainage that must be treated. Exercise care, since this wastewater is acidic! Using
a lime solution, adjust the pH of the sample to 8.0. If lime is not available, any alkaline compound can be used to raise the pH. If chemical additions for pH control are already being made at the mine site, a sample of this pre-treated water can be used for the permanganate test.
A pH adjustment to near 8.0 is important because:
It raises the drainage pH to within EPA guidelines (pH between 6-9)
The iron precipitates in the wastewater as Fe(OH)3 - It reduces the CAIROX® demand by removing some of the manganese, thus saving money.
pH ADJUSTMENT
- Prepare an alkaline solution in water. Lime is often used as a 1 gram/liter solution.
- Measure the pH of the sample using an appropriate device e.g., a pH meter, litmus paper, etc.
- Titrate the sample using the prepared alkaline solution until the pH is 8.0.
ANALYZE SAMPLE FOR DISSOLVED IRON AND MANGANESE
- The sample is analyzed for dissolved iron and manganese.
- Allow the solids in the jar to settle and filter some of the sample through 0.22 micron filter paper.
- Determine the amount of dissolved iron and manganese in the filtered solution by standard test procedures.*
- It is possible that with pH adjustment alone the sample may be within EPA standards. If not, the remaining iron and manganese can be removed by treating the sample with CAIROX® potassium permanganate or ECONOX™ liquid permanganate.
*The procedures can be found in the most recent edition of Standard Methods, for the Examination of Water and Wastewater, Part 3000 prepared and published jointly by the APHA, AWWA, and WPCF, New York.
ECONOMICS
To determine the theoretical cost of successful treatment, proceed in the following manner:
Assume a dose of 20 mg/L resulted in satisfactory removal of iron or manganese. This dose is equivalent to 20 x 8.34 lbs, or 166.8 lbs of CAIROX® per million gallons of water to be treated.
Using the appropriate cost of CAIROX®, multiply 166.8 pounds times $/lb of CAIROX® to obtain the cost of treating one million gallons.
To determine actual costs, a plant trial may be required.
ECONOX™ liquid permanganate is a highly concentrated (20%) liquid permanganate that is easy to handle, feed, and is more effective at lower temperatures (-12 °C). The cost of treatment for the above example is 20 ppm x 37.5 lbs or 748 pounds of ECONOX™ x $/lb of ECONOX™ liquid permanganate.
