Testing of different substrate materials for sulphate reducing reactive barrier to treat acid mine drainage

The aim of this study was to find cheap, solid substrate material for sulphate reducing bacteria (SRB) to be used in permeable reactive barrier (PRB) and infiltration beds to treat acidic, nickel-, copper- and iron-rich mine drainage. Laboratory experiments were carried out to examine the reactivity and utilisation of different substrate materials. The materials of interest were peat, sawdust, cucumber compost and cellulose. Limestone, phosphorus and nitrogen were added to the mixture to create optimum growth conditions for SRB. Based on a batch tests, cucumber compost was chosen to be examined in larger-scale column tests. Results from the column tests were promising. Nickel (43 mg L-1), copper (24 mg L-1) and iron (95 mg L-1) were precipitated almost completely and the concentration of sulphate was decreased approximately 20 %. pH values increased from 2.7 to 8. Based on laboratory tests results it appears that cucumber compost was suitable substrate material for SRB in PRBs and infiltration beds treating AMD.