SULPHATES REMOVAL FROM ACID MINE DRAINAGE

Acid mine drainage (AMD), the highly acidic, dissolved metals and sulphates containing wastewater is a persistent environmental problem related to many active and abandoned mine sites. It is formed by geo-chemical reactions that occur when sulphidebearing minerals are exposed to oxidizing conditions and water. Untreated AMD pollutes receiving streams and subsurface waters by toxic metals and sulphates and causes destruction of the environment. Various treatment techniques of AMD have been developed during the recent time to reach neutralization of the waters and elimination of dissolved metals and sulphates. Our work is focused on the biological removal of sulphates from AMD by way of anaerobic reduction to sulphide using sulphate-reducing bacteria (SRB). For cultivation of SRB various growth substrates were used - sodium lactate, ethanol, sweet whey and acid whey. The experiments were performed using real water collected from the site of the AMD outflow at the shaft Pech that receives the mass of waters draining the enclosed and flooded Smolnik sulphidic deposit. Before the process majority of metals (Fe, Al, Mn, Zn, Cu) have been eliminated from AMD by selective sequential precipitation. The sulphates removal with efficiency 83 %, 58 %, 43 % and 11 % from pre-treated AMD has been achieved depend on the growth substrates used for cultivation of SRB.