Under the topic of information needs for mine closure and abandonment, the MPERG priorities for funding in 2009 included an investigation of the use of bioremediation as a treatment option for active and abandoned mine drainage. From the 2009 MPERG call for proposals: “The use of various “passive” treatment technologies is being proposed as a possible panacea to provide efficient, cost effective treatment of pit water and metal bearing water discharges. The long term effectiveness of these treatments in a northern environment needs to be investigated.” Passive treatment of some kind has been considered for many years due to its appeal in comparison with mechanical-chemical treatment plants which are now required to operate almost in perpetuity at many closed mine sites. An observation that makes bioremediation so attractive are the many natural analogues observed around mine drainages that naturally attenuate or otherwise reduce metals burden in mine drainage without apparent harm to the host aquatic ecosystem. These include fen-bogs, swamps and other wetland structures which renovate mine drainage; effectively removing and in many cases sequestering contaminants. The original term “wetland treatment” has given way to “passive treatment” and/or “biological treatment” in recent years.
