Natural system for combined treatment of mine tailings and industrials landfill leachates

摘要

Water in Camp Branch, next to U.S. Steel's abandoned Edgewater Mine tailings pile, has a low pH and contains high sulfate, iron, manganese and zinc concentrations. Part of the water originates from precipitation, surface and groundwater flowing through the Edgewater Mine tailing pile and part from the nonpoint source discharge of leachate from U.S. Steel's Exum materials storage and disposal facility. U.S. Steel retained CH2M Hill to develop this concept and design a demonstration wetland treatment system. A passive, low-cost, low maintenance system was designed and installed that uses a trench to collect the two nonpoint sources. The system has an engineered anoxic trench that increases pH by contacting the wastewater with high calcium limestone, precipitates metal hydroxides in a sedimentation pond without chemical addition, and uses both constructed and natural wetlands to remove sulfate, total dissolved solids and heavy metals from the water. Primary results indicate higher than design influent Ph and iron levels. Removal of iron and manganese has been limited because of lack of oxygen in the sedimentations and subsequent ponds.