Abstract
The efficacy of passive treatment systems for remediating acid rock drainage can be limited by the seasonal flux of discharge and metal concentrations that may not have been considered during treatment design. A review of passive treatment options for acid rock drainage indicates reduced efficacy due to seasonal periods of increased drainage and metal concentrations that lead to mineral precipitation, surface passivation, and flow bypass. In select cases, passive treatment systems prematurely failed due to seasonal flux or experienced substantially reduced treatment efficacy and life of the system. Complimentary systems are needed to minimise impacts from seasonal flux of drainage and metal concentrations to improve treatment efficacy and preserve the life of a multi-component system or a downstream primary system. Multi-component systems are possible with integration of existing treatment systems and design of new treatment options to tailor treatment to site specifications.