First steps in assessing microbial involvement in the geochemical evolution of uranium mine tailings : evaluation of iron reduction potential, biofilm formation and community heterogeneity

The  high  pH  (~10)  and  elevated  concentration  of  metals  and  oxyanions  such  as  As,  Fe,  Ni,  Mo  and  Se  in  the  Deilmann  tailings  management  facility  (DTMF)  presents  a  highly  selective  environment  for  microorganisms.  The  objective  of  this  study  was  to  assess  the  potential  for  metal  and  ion  solubilization  by  the  indigenous  mixed  microbial  community  in  both  optimum  (high  carbon)  and  in-situ (low  carbon  alkaline  environment)  conditions  in  terms of bulk pH and redox potential in order to satisfy the requirement for calculating long term stability. A flow-cell system was developed in order to monitor the extent of microbial metal   reduction   as   well   as   determine   biofilm   formation   by   tailings-isolated   mixed   communities.  The  microbial  consortium  isolated  from  the  DTMF  has  shown  the  ability  to  reduce ferric iron for energy conservation under both carbon conditions.