Characterization and performance of local organic materials for passive treatment systems of mine drainage in Yukon

Passive treatment systems (PTS) present a potential low-cost solution to treating mine-impacted waters (MIW) and impeding release of contaminants, such as metals and sulphate, into receiving waters in remote mine sites in Yukon. Nevertheless, the traditional carbon substrates used to maintain efficient functioning of these systems (i.e., molasses) are not readily available and can be expensive in remote locations. Moreover, the extensive periods of cold temperatures experienced in Yukon may impede the biological functioning of PTS. The goal of this study is to characterize a selection of local organic materials that may be used as complex carbon substrates for PTS and evaluate their potential performance as carbon substrates in the Yukon environment. In the first part of the study, the physiochemical properties of six local complex carbon substrates: willow leaves (Salix sp.), sedges (Carex sp.), peat, peat moss (Sphagnum), poplar (Populus sp.), wood chips, and spruce (Picea sp.) wood chips were characterized. In the second part, bench-scale bioreactors containing organic substrates, were used to evaluate carbon substrate degradation and the performance of bioreactors for sulphate and metal reduction from synthetic mine water at low temperatures for approximately five months.