ABSTRACT
The importance of microorganisms as catalysts of inorganic chemical reactions has been recognized in commercial metal recovery and soil mineral transformations. More recently, the importance of microbially mediated reactions with respect to environmental concerns has been documented. These reactions are presented with their relevance to the generation, prevention, and abatement of acidic drainage. Bacterial sulfide mineral oxidation is the principal cause of sulfuric acid generation in base metal tailings, coal spoils, and quarry effluents. In biological mineral oxidations, the mineral is the oxidizable substrate, oxygen is generally the oxidant, and an enzyme system of microorganisms is the promoter. The three components of acid generation reactions are the mineral substrate, the oxidant, and the biological catalyst. Of chemical, physical, and biological abatement options, only those with a substantial biological component offer freedom from perpetual maintenance. Permanence depends on self-regenerative properties of biological systems that are integral functions of metabolism and interactions of all the components of these systems.
