Challenge
The Minnesota Department of Natural Resources (DNR) needed to meet stringent discharge limits for copper and cobalt in their Soudan Mine facility. The facility is a former iron mine that was converted to a state park. Copper and cobalt from surrounding geological formations leach into water and exceed current discharge limits.
Solution
The DNR has been utilizing two Evoqua wastewater ion exchange systems in the mine to treat these concentrated levels. Despite the effective treatment in the mine, additional sources of copper and cobalt contributed to elevated levels of metals in the overall 150 gpm discharge.
In 2009 the DNR implemented wastewater ion exchange in their total mine discharge. Due to the ease and flexibility of upgrading vessels and modifying the media within a wastewater ion exchange system, the DNR now has the capability to treat increased springtime flows up to 300 gpm by installing additional banks of wastewater ion exchange vessels in parallel configurations.
Results
DNR met their discharge limits with a wastewater ion exchange service while eliminating the need for on-site chemicals required by other treatment systems. As the DNR's requirements evolved, and springtime flows needed to be addressed, Evoqua was able to provide treatability studies, engineering recommendations and a system to allow compliance with the mine's discharge permit.