The field is located at the site. Credit: Jeff Bain
The Long Lake Gold Mine, which ceased operations in 1937, produced 200,000 metric tons of tailings, which were discharged directly to the environment without containment.
A team of researchers from the University of Waterloo have shown that a passive form of remediation that uses common waste materials can remove most of the arsenic from samples of the lake water. The Journal of Hazardous Materials has their results.
The scientists found that mixing wood chips, leaf mulch, and iron filings with limestone creates conditions that encouragebacteria to grow. The arsenic is pulled from the water by converting it to a solid form that is trapped within the waste material filter.
The lead author of the study was a student at the University of Waterloo. She said that passive treatment is cost-effective. She stated that active treatment involves pumping water out of the ground, then putting it back in. Monitoring the process costs less and there are fewer ongoing requirements.
Carol Ptacek is a member of the research team and co-supervisor on Angai's thesis. Ptacek said that it helps mitigate or reduce the greenhouse gas emissions associated with active treatment systems.
The researchers used a variety of different techniques to determine what happened when they pumped contaminated lake water through columns of reactive material. They found that the arsenic concentration had decreased when they tested samples of water that had passed through the mixture.
The team used the SXRMB beamline at the Canadian Light Source to examine the core samples of the waste material and found that almost all of the arsenic was trapped in a mixture of arsenic sulfides and arsenic bound to iron minerals. Ptacek says that they were able to generate useful results from the study because they had access to the CLS beamline. Ptacek says that the characterization of the reaction product was provided by the synchrotron.
This is the first study to show that the method is effective when used with low pH, arsenic heavy water. Ptacek and David Blowes were graduate students at the University of Waterloo in the late 1980s and early 1990s when they developed and patented the use of organic carbon and zero valent iron for remediation. They discovered the advantages of combining the two waste materials after initially using them separately.
Blowes said thatJoanne's work shows that it's possible to treat water. We'll push these types of systems further into more extreme conditions than we have in the past. This opens up the door to treat a lot of lower-pH water and higher concentrations than we've considered before.
Blowes said that the new approach could be applied to the ongoing efforts at the site.
The removal of arsenic and metals from the ground using zero-valent iron and organic carbon was studied in a laboratory column experiment. There is an article titled "Jhazmat 2021."
The Journal of Hazardous Materials has information.
A new method uses waste to clean arsenic from a lake that has been polluted by a gold mine.
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