Importance of catchment vegetation and design to long-term rehabilitation of acidic pit lakes

Document Type

Conference Proceeding


International Mine Water Association


Faculty of Health, Engineering and Science


School of Natural Sciences / Centre for Ecosystem Management




This article was originally published as: Lund, M. A., Van Etten, E. J., & Mccullough, C. D. (2013). Importance of catchment vegetation and design to long-term rehabilitation of acidic pit lakes. In Reliable mine water technology: Proceedings of the International Mine Water Association Annual Conference 2013, August 6-9, 2013, Golden, Colorado, USA (pp. 1029-1034). Golden, USA: International Mine Water Association. Original article available here


Acidic pit lakes may form in open cut mine voids that extend below the groundwater table and fill from surface and groundwater in-flows at the cessation of mining. Pit lake water quality may often be affected by acid mine drainage (AMD). Among the many remediation technologies available, sulphate reducing bacteria (SRB) based bioremediation using organic wastes appears to have significant potential towards ameliorating AMD effects of elevated acidity, metal and sulphate concentrations. A microcosm experiment was carried out under controlled conditions to assess the effect of different substrate concentrations of sewage sludge on AMD bioremediation efficiency. Experimental microcosms were made of 300 mm long and 100 mm wide acrylic cores, with a total volume of 1.8 L. Four different concentrations of sewage sludge (ranging 30–120 g/L) were tested. As the sewage sludge concentration increased the bioremediation efficiency also increased reflecting the higher organic carbon concentrations. Sewage sludge contributed alkaline materials that directly neutralised the AMD in proportion to the quantity added and therefore plays a primary role in stimulating SRB bioremediation. The lowest concentration of sewage sludge (30 g/L) tested proved to be inadequate for effective SRB bioremediation. However, there were no measurable beneficial effects on SRB bioremediation efficiency when sewage sludge was added at concentration >60 g/L