Performance and bacterial community shifts during bioremediation of acid mine drainage from two Portuguese mines

The performance of two up-flow anaerobic packed bed systems (UAPB) to treat acid mine drainage (AMD) from the Portuguese mines São Domingos and Tinoca was investigated. The response of bacterial populations to influent characteristics was also analysed by temperature gradient gel electrophoresis (TGGE). Effective neutralisation (pH raised from 2.8 to 6.5) and removal of metals (>99%) and sulphate (>72%) were observed independently of the AMD source. TGGE fingerprinting and phylogenetic analysis of 16S rRNA gene revealed that the structure of the bacterial consortia developed in each bioreactor was different. The main bacterial groups involved in the treatment of AMD from Tinoca mine were Desulfovibrio sp., Clostridium sp., Desulfitobacterium sp. and members of Bacteroidales order. These bacterial groups were also present in the community developed in the UAPB fed with AMD from São Domingos mine but an unidentified bacterium and bacteria affiliated to Citrobacter and Cronobacter genera were detected only in this last system. The results of present study showed that the AMD source fed to the system was determinant for the establishment of different bacterial populations. Furthermore, the potential of the bioremediation systems for the production of water for irrigation purposes was demonstrated.

► The performance of a bioremediation system to treat real acid mine drainage (AMD) was investigated. ► The production of water for irrigation purposes from AMD was demonstrated. ► The temporal evolution of the bacterial population during bioremediation was studied. ► The results showed that the AMD source was determinant for the establishment of different bacterial populations.