Bioremediation of an industrial acid mine water by metal-tolerant sulphate-reducing bacteria

The microbiological diversity associated with mining environments is a very well proven fact. One of the communities appearing in these environments is that formed by anaerobic sulphate-reducing bacteria (SRB) which can be used for the decontamination of acid mine drainage waters. In this work, the potential of a mixed population of SRB, isolated from the bottom of a pyritic tailing pond situated in the Spanish pyritic Belt, has been investigated with the main objective of treating the effluent generated in the same disposal site. The efficiency of the system is based on the presence of an important amount of reducing agents contained in the acid mine drainage received in the pond. Results showed that this option is effective for the precipitation of the dissolved metals (copper and iron), for the reduction and removal of sulphates and even for the alkalising of the waters. SRB were able to remove up to 9,000 ppm of sulphate ion efficiently, to grow in the presence of up to 100 ppm of copper and 30 ppm of iron, and alkalise the medium, provided that this was not extremely acidic (pH>4). Finally, according to the results obtained, the possibility of applying this method to the treatment of a real effluent is discussed.