As the exploration and production phases of gold mining operations in the Yukon Territory increase, there is substantial emphasis being placed on the development of remediation technologies to treat mine-impacted water (MIW) during closure and post-closure phases. The mining industry, as well as environmental protection agencies, specific departments within the government and First Nations, have been interested in the research and development of remediation methods to treat heavy metals such as selenium (Se), as well as metalloids such as antimony (Sb), and arsenic (As),all of which are commonly found in wastewaters of Yukon mines. Of particular interest to all stakeholders, is the development of passive or semi passive treatment technologies and bioremediation techniques, which make use of bacteria endemic to the Yukon Territory for the purpose of removing harmful concentrations of these contaminants. In addition to focusing on bioremediation, an emphasis on passive adaptations to these techniques has been highly sought after for its promise of reduced human intervention, and as a result, reduced costs.
Four pilot-scale bioreactors (BRs) were installed in August 2019, at the Eagle Gold mine. The BRs were installed in duplicates; two were installed in the YukonU Research Centre (YRC) shed, and two were installed outside of the shed, to evaluate the impact of freeze and thaw seasonal cycles on the bacterial population. The two BRs within the shed were heated to maintain a minimum temperature of 5°C all year. The two BRs located outside of the shed, went through the natural freeze and thaw processes throughout the seasons. This set up, more specifically the bacterial population contrast measured in the BRs located outside the shed versus within the shed, will help indicate the physiological adaptation of the community to freeze and thaw cycles on site.