Growth of sulfate-reducing bacteria under acidic conditions in an upflow anaerobic bioreactor as a treatment system for acid mine drainage

The aim of this investigation was to develop a system for the remediation o f acid mine drainage using sulphate-reducing bacteria. An upflow porous med ium bioreactor was inoculated with sulphate-reducing bacteria (SRB) and ope rated under acidic conditions. The reactor was operated under continuous fl ow and was shown to be capable of sulfate reduction at pH 4.5, 4.0, 3.5 and 3.25 in a medium containing 16.1 mM sodium lactate. This contrasted previo usly published work which showed that, at pH 3.8, organic acid concentratio ns greater than 5 mM completely inhibited biological sulfate-reduction. At pH 3.25 the reactor removed 38.3% of influent sulfate and raised the pH of the medium to 5.82. The lactate carbon source was exhausted under these con ditions. At pH 3.0, sulfide production was below detectable levels, and sul fate removal fell to 14.4%. However, viable SRB were recovered from the col umn after 21 days of operation at pH 3.0, indicating that SRB are capable o f withstanding pH 3.0 for extended periods. From these results we can concl ude that an SRB process would be a viable method of remediating AMD. (C) 19 98 Elsevier Science Ltd. All rights reserved.