"September 1971." Cover title. Includes bibliographical references (pages 77-78).

The purpose of the study was to determine if the abilities of certain bacteria to oxidize ferrous iron or to convert sulfate to hydrogen sulfide could be applied to the neutralization and subsequent removal of iron from difficult-to-treat mine drainage waters. If one or both of these concepts could be successfully utilized, the expense of adequately treating these types of problem waters might be significantly reduced. Laboratory studies demonstrated that both pure cultures and fresh field cultures of acidophilic iron bacteria could readily oxidize ferrous iron in both synthetic and natural acid mine drainage waters. Approximate requirements of oxygen, carbon dioxide, nitrogen and phosphorus by the iron bacteria were established. Limestone neutralizations of partially oxidized acid mine waters were conducted. Although sulfate-reducing bacteria were isolated, attempts to grow the cultures or produce hydrogen sulfide at pH values below 5.5 were unsuccessful.