ACTIVATED IRON SOLIDS TREATMENT FOR HIGH FLOW ACIDIC MINE DRAINAGE: RESULTS OF PILOT STUDIES

摘要

Historic coal mining in the eastern United States coal regions has created numerous large underground reservoirs of iron-laden acidic mine drainage (AMD) that can discharge at very high volumes (> 50 L/s) and cause aesthetic and water quality degradation to the receiving surface waters. This degradation can all but eliminate aquatic life in receiving waters through the accumulation of iron solids, also known as "yellowboy". Conventional active treatment (e.g., lime) is costly and produces low-density (1-4% solids) and impure sludge. The high treatment cost generally limits its application to regulatory AMD discharges. The size of passive treatment (80 to 800 hectares for high flow discharges) typically limits this approach to lower flow AMD discharges. Activated Iron Solids (AIS) treatment of AMD is a new treatment process that uses heterogeneous ferrous iron oxidation, a catalytic process associated with the surfaces of insoluble ferric hydroxides. In this process, dissolved ferrous iron is adsorbed to the ferric hydroxides where rapid oxidation to ferric iron forms new iron hydroxides.