Acid mine drainage is accelerated and perpetuated by acidophilic bacteria such as Thiobacillus which derives energy from the oxidation of inorganic compounds. But nature always seeks balance and provides the means to correct the problem.

Bacteria such as Desulfovibrio are sulfate reducers which reverse the effects of the acidophiles. They oxidize organic materials by using the sulfate ion as an electron acceptor. This produces sulphide (S-) which reacts with metal ions, immobilizing both the sulphur and metals as metal sulphides.

Sulfate reducing bacteria (SRB) are ubiquitous in the environment. They thrive in the midst of rich deposits of organic carbon and in the absence of oxygen. For example, sediments at the bottom of water bodies are ideal habitats for SRB, as are wet, humus-rich soils. Unfortunately, such habitats are scarce on mine sites where soils are pushed aside by heavy equipment or buried by waste rock.

To build these organic sediments in mine site ditches and erosion gullies, they are damned to slow the escape of contaminated water. Organic matter is added to the resulting ponds to begin the formation of organic, anaerobic sediments. In some cases other treatment ponds are added upstream to oxidize reduced iron leaching from tailings deposits. The treatment ponds are then covered with living, floating covers (see FLOATING CATTAIL COVERS) to a) provide organic carbon to developing sediments, b) reduce oxygen content of overlying water to promote anaerobic conditions underneath, c) reduce mixing and turbulence to promote stratification within the water column.

ARUM was developed with the assistance of the Canadian MEND program. Technical reports are available at MEND and Laurentian library.

For more information refer to our publications and reports below.

For a PDF, please send an email to: margarete.kalin@utoronto.ca

J15 Kalin, M., A. Fyson and W.N. Wheeler, The chemistry of conventional and alternative treatment systems for the neutralization of Acid Mine Drainage, Science of the Total Environment, DOI:10.1016/j.scitotenv.2005.11.015

J8 Kalin, M. and W.L. Caetano Chaves, Acid Reduction Using Microbiology:  Treating AMD Effluent Emerging from An Abandoned Mine Portal, Hydrometallurgy, 2003, (71:1-2) pp. 217-255.

C87 Kalin, M., A. Fyson and M.P. Smith, Maintenance-Free Microbial Treatment of AMD: Four Years of Performance.  Proceedings of the Sudbury ’99 Mining and the Environmental II Conference, Sudbury, Ontario, September 13-15, 1999, pp. 1153-1161.

C68 Kalin, M., A. Fyson and M.P. Smith, Microbially-Mediated Metal Removal from Acid Mine Drainage. Proceedings of the Mining and Environment Conference, Sudbury, Ontario, May 28-June 1, 1995, pp. 459-466, Vol. II.