The RCTS replaces the reaction vessels, compressors, diffusers and agitators found in conventional systems. Oxidation and mixing is accomplished by passing acid mine drainage and lime slurry through a containment cell, in which a perforated cylinder rotates. As the cylinder rotates, a thin film of water adheres to the inner and outer surfaces where gas exchange occurs. In addition, water bridges across the perforations for additional gas exchange. The agitation is provided primarily by the impact of the perforations with the water flowing through the containment cell. Air is forced into the water where additional gas transfer can occur. The turbulence that is produced provides efficient lime mixing and dissolution, which results in less lime consumed due to the utilization of the available alkalinity, and less sludge produced as a result of less lime usage.
On the three sites tested the RCTS utilized 31%-51% less lime. Comparisons of sludge settling rates with a conventional system revealed a near threefold increase in settling rates. On a site that required manganese oxidation and removal the RCTS oxidized and precipitated 26 mg/L of manganese to less than 0.08 mg/L at pH 9.75 with less than 2 minutes residence time. In all of the studies the RCTS effectively precipitated metals and increased pH, on sites that compared the RCTS with conventional treatment the RCTS system required substantially less energy, chemical, labor and residence time.