Deborah Roberts has identified microbes responsible for acid-rock drainage at mine sites. — Photo courtesy UBC Okanagan As an environmental concern
Deborah Roberts has identified microbes responsible for acid-rock drainage at mine sites. — Photo courtesy UBC Okanagan
As an environmental concern and a drain on time and costs, mining waste is an issue that mining operations face around the world, said Deborah Roberts, professor of engineering at UBC's Okanagan campus.
Thanks to Roberts' research to isolate micro-organisms contributing to acid-rock drainage, additional studies could lead to managing the issue with antibiotics, similar to the way other bacterial infections are treated.
During the two-year study, researchers identified and isolated three types of sulphur-oxidizing bacteria and two types of iron-oxidizing microbes active at low temperatures that contribute to the rapid production of acid in mining waste.
Roberts examined tailing samples from mining operations in Alberta, focusing on the types of organisms present and how they behaved at different temperatures.
“In a complementary study we are just writing up for publication, we have determined that temperature does affect the growth and acid production rate,” she said. “Lower temperatures slow the rates down, but they are slow but still active at 4 C. They are not active above 35 or 40 C.”
According to Natural Resources Canada, there are currently two primary methods of long-term tailings management—tailings ponds or dry covers.
This study could result in a third method, which would return mining waste to its natural state without ponds or dry covers.
“The treatment option we envision would be to spray the rocks or tailings with a virus that targets the organisms that cause acid production,” said Roberts. “The virus would infect the cells and cause them to break open, releasing new virus to kill more cells.
“Because there is more than one type of organism, we would apply a cocktail of viruses so we can control the growth of multiple organisms.”
The idea for the research occurred to Roberts 15 years ago while she was looking at controlling concrete corrosion, because it is caused by the same organisms.
The current work to control acid mine drainage had been ongoing for about three years.
Roberts said besides isolating the organisms, she has shown that she can grow them in the laboratory. Her bioinformatics study shows there are viruses that attack these organisms present in some environments.
“We are looking for funding to perform the studies that will allow us to isolate the viruses, grow them in large amounts and do a pilot test to determine the efficiency of the application of the virus cocktail for long-term control,” she said.
