Abstract: A passive treatment system for removing metals, especially manganese, from mine drainage and other aqueous solutions. The Hybrid Flow Pond (HFP) is an open, pond-like structure utilizing a horizontal or vertical operational flow path through a bed of treatment media together with a vertical flow path for flushing accumulated solids from the bed. The bed preferably contains basic steel slag, limestone, marble, blast furnace slag, other types of slag, organic material, or mixtures thereof. In another aspect of the Hybrid Flow Pond, a tiered piping system divides an interior of the treatment bed into cells. Each cell has its own header and adjustable riser whose output level can be raised or lowered to change the head experienced by each cell.

Abstract: The slag-only Vertical Flow Pond, which we have developed, is a passive treatment component capable of removing large concentrations of metals, especially manganese, from water to extremely low concentrations while neutralizing acidity and producing alkalinity. An improvement to this design is the Hybrid Flow Pond (HFP), which is a passive treatment system component that consists of an open, pond-like structure utilizing a horizontal operational flow path (or a vertical flow path if desired) with a vertical flush flow path. By creating flushing flow paths generally perpendicular to operational flow paths, the development of preferential flow paths that encourage short circuiting can be prevented. Additional head can be generated prior to flushing by adjusting the water level in the pond. Although any treatment media can be used with this system, the use of basic steel slag is particularly useful in the removal of metals, especially manganese from aqueous solutions.