Use of Ozone to Remediate Manganese From Coal Mine Drainage Waters

Manganese is an aesthetically undesirable metallic element that is difficult to remove from mine drainage that has acidic to neutral pH. In spite of the thermodynamic prediction that oxygen in the atmosphere or in solution should oxidize dissolved manganese (Mn 2+ ) to an oxide or a hydroxide, this does not happen in acidic aqueous solutions. The capability of ozone to oxidize and precipitate manganese as an oxide was proven in bench-scale experiments at U.S. Geological Survey (USGS) labs, and the process was granted U.S. patent no. 6,485,696. Ozone (O3) oxidizes Mn 2+ to MnO2 (Mn 4+ ) as follows: 3Mn 2+ + O3 + 3H2O = 3MnO2 + 6H + (1)