The Rotating Biological Contactor for Biochemical Ferrous Iron Oxidation in the Treatment of Coal Mine Drainage.

摘要

Pilot scale testing of the rotating biological contactor for the oxidation of ferrous iron in acid coal mine drainage has shown the process to be dependable,efficient,and economically comparable to purely chemical methods of iron oxidation. The 0.5meter device consisted of four sets of plastic discs affixed to a centralized shaft. As the discs rotated half immersed in flowing mine water,an average iron-oxidizing bacterial population of 70,000cells per sq cm colonized the disc surfaces without prior bacterial preseeding or nutrient supplementation. Concentration dependent first order kinetics were established during continuous operation from May 1974through March 1975at several hydraulic loadings and disc rotation rates. Hydraulic loadings of 2.7and 5.4gpd/sq ft (0.11and 0.22cu m/day/sq m) at optimum disc rotation resulted in the transformation of an average 240mg/l influent ferrous iron to produce effluents of 2and 5mg/l,respectively. Performance was not impaired when operated at mine water temperatures as low as 8C and the process was shown to recover rapidly when subjected to artificially induced toxicity in the form of a strong disinfectant solution. The process prepared a coal mine drainage containing up to 313mg/l of ferrous iron for limestone neutralization and subsequent solids precipitation at an estimated operating cost of 4cents per thousand gallons (1cent per cu m).