A study was conducted at a site adjacent to I-65 site near Hobart, IN. The pilot scale study was designed to evaluate the use of a subsurface constructed wetland to treat leachate from the slag-based embankment. The constructed wetland proved to be effective in reducing a number of the leachate constituents that impact surface water quality, including pH, TDS, salinity, and sulfate. The system worked best under low flow conditions and extended retention times between surges of leachate into the wetland. The zero flow restriction of the system was met and resulted in elevated concentrations of salts and metals in the sediments. Treatment of the slag leachate could be enhanced through the use of a flow-through system that utilizes different options: reciprocating flow regime, alternating organic substrate, and process segmentation to utilize both aerobic and anaerobic processes. A better understanding of the speciation of target pollutants also would be beneficial in determining the fate and availability of the compounds. Additional analyses of substrate and precipitation products after treatment in conjunction with the modeling of chemical equilibra would be useful to determine if reaction rates are optimized.

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constructed wetlands, contamination, runoff, slag, heavy metals, sulfate, surface water, environmental impact, phytoremediation, SPR-2780

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Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

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