Bacterial Oxidation of Coal

The problem of stream pollution caused by acid mine drainage has prompted several studies (Leathen, 1952 Leathen et al., 1953a,b Braley, 1954 Temple and Koehler, 1954 Ashmead, 1955 Moulton, 1957 Beck, 1960 Brant and Moulton, 1960 Hoffman et al., 1981 Atkins and 

Pooley, 1982 Atkins and Singh, 1982 Wang et al 2007). These investigators agree that the ultimate source of the sulfuric acid and iron pollutants is the pyritic material associated with coal and coal-bearing strata. 

Oxidation of these iron disulfides results in the production of ferrous sulfate and sulfuric add. Subsequent oxidation of ferrous sulfate yields additional sulfuric add and hydrated oxides of iron. The latter forms the unsightly yellow-to-red muds characteristic of streams receiving acid mine drainage. 

Iron-oxidizing and sulfur-oxidizing chemoautotrophs have been isolated repeatedly from add waters, both in United States (Colmer and Hinkle, 1947 Leathen and Madison, 1949 Colmer et al., 1950 Bryner et al., 1954 Brant and Moulton, 1960) and in Europe (Ashmead, 1955 KuUerud and Yoder, 1959 Zarubina et al., 1959), and have been shown to accelerate the rate of oxidation of pyrite and other sulfide minerals. These workers measured pyrite oxidation by titrating for increased acidity, or by determining the release of soluble iron or sulfate S from the insoluble minerals. 

The use of iron-oxidizing autotrophs in the removal of pyrite from coal (Ashmead, 1955 Zarubina et al., 1959) and in the secondary recovery of copper and molybdenum from their sulfide minerals has already been reported (Bryner et al., 1954 Bryner and Anderson, 1957 Bryner and 

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