Overview of the sulfate-reducing bacteria demonstration project under the mine waste technology program

摘要

This paper presents results from pilot-scale and field testing of an innovative technology that uses sulfate-reducing bacteria (SRB) to treat and control acid mine drainage (AMD). Sulfate-reducing bacteria, a common group of anaerobic bacteria,produce hydrogen sulfide and bicarbonate when supplied with sources of carbon and sulfate. Hydrogen sulfide reacts with metal ions in AMD, precipitating them as metal sulfides. The bicarbonate produced serves to help neutralize the drainage. Pilot-scalemetal-removal efficiencies reached 99% for zinc, 99% for aluminum, 96% for manganese, 98% for cadmium and 96% for copper. However, the iron and arsenic removals were not as effective as the aforementioned metals. This was largely attributed to high levels of iron and arsenic that contaminating the organic substrate. There was evidence that both adsorption and sulfate reduction were occurring within the reactors. The SRB field demonstration involved using the flooded subsurface mine workings of theLilly/Orphan Boy Mine near Elliston, MT, as an "in situ biological reactor. "In the mine, high removal efficiencies were observed for aluminum, cadmium, copper and zinc (70% to near 100%) during the four years of monitoring. However for reasons similar to the pilot scale testing, low removal efficiencies were observed for arsenic and iron. Sulfate reduction was evident by measured decreases in sulfate and the detection of soluble sulfide within the mine water.