WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: 2004AZ42B
Title: Permeable Reactive Biobarriers for the Containment and Remediation of Acid Mine Drainage
Project Type: Research
Focus Categories: Toxic Substances, Groundwater, Treatment
Keywords: Acid Mine Drainage, Ground Water, Heavy Metals, Metalloids, Toxic Substances, Mining, Smelting Sites, Bioremediation, Permeable Reactive Barriers, Biomineralization, Microbial Reduction, Sulfate Reduction
Start Date: 03/01/2004
End Date: 02/28/2005
Federal Funds: $11,678
Non-Federal Matching Funds: $24,270
Congressional District: 07
Arizona has a long history of mining and ore smelting. The uncontrolled release of acid mine drainage (AMD) from abandoned mines and tailing piles threatens the State’s water resources. AMD introduces elevated concentrations of sulfate, ferrous iron and other dissolved metals as well as radionuclides to groundwater and receiving surface water. Metals and metalloids are the most important pollutant category responsible for the impaired or non-attaining streams in Arizona. Metals and radiochemicals are also problematic groundwater pollutants responsible for many wells exceeding drinking water standards. The overwhelming majority of Arizona's mining or tailings impacted sites are no longer in industrial operation. Consequently, cleanup funds are limited, leaving only low-cost extensive treatment or containment as viable options.
This project will examine the potential of permeable reactive biobarriers (PRBs) to prevent the spread of acidity, sulfates, and metals from AMD to surface or groundwater. PRBs are porous biologically-active trenches used to intercept and remediate contaminated plumes. In this project, the activity of sulfate reducing bacteria will be promoted in order to convert sulfate to sulfide, which will subsequently precipitate a wide spectrum of metal and metalloid contaminants as sulfide minerals. The research specifically examines the applicability of utilizing slow-release electron donating substrates to support microbial activity over extended periods of time. Various organic substrates as well as different formulations of zero valent iron (Fe0) will be evaluated as potential long-lived electron donors in batch assays. The most promising slow-release electron donors will be tested in laboratory-scale PRBs for the remediation of AMD laden with a cocktail of heavy metals. The project will result in the development of a concept for the low-cost containment of AMD. Successful application of this technology will benefit rural citizens living in mining-impacted areas by protecting precious water resources, as well as citizens and tourists that enjoy the natural water resources of Arizona for recreational purposes.