Arsenic had leached into the lake from tailings at the abandoned Long Lake Gold Mine. It operated intermittently until 1937. It produced approximately 200,000 metric tons of tailings which is discharged directly to the environment without containment.
University of Waterloo researchers have shown that a passive form of remediation that uses common waste materials can remove virtually all of the arsenic from samples of the lake water. The study has been published in the Journal of Hazardous Materials.
Scientists found mixing wood chips, leaf mulch and iron filings with limestone makes conditions that encourage bacteria to grow. The bacteria pull the arsenic from the water by turning it to a solid form which is trapped within the waste material filter.
There are little ongoing operational requirements. Lower costs are also associated with monitoring the process. Scientists used a variety of different techniques. Like water chemistry, next-generation genomic sequencing and synchrotron studies.
They wanted to determine what reactions happens when they pumped contaminated lake water through acrylic columns which was packed with the reactive material. They tested the samples of water which passed through the mixture. Scientists found out the arsenic concentration had decreased significantly.
Scientists used the SXRMB beamline at the Canadian Light Source at the University of Saskatchewan. They examined core samples of the waste material. Then they confirmed it had trapped virtually all of the arsenic as a mixture of arsenic sulfides and arsenic bound to iron minerals. Scientists have access to the CLS beamline. They enabled them to generate useful results from the study.
This approach for capturing contaminants from groundwater before they reach surface water has been applied in other projects of cleanup. This study shows the method is effective when used with low pH, arsenic-heavy water. Scientists developed and patented the use of organic carbon and zero valent iron for remediation. It happened in the late 1980s and early 1990s. Scientists used the two types of waste materials separately and discovered the advantages of combining the two.