Wetland Sediment Pb Reduction and Immobilization Study
ARS is currently conducting a bench-scale treatability study to evaluate the potential of using our FEROXSM process to reduce lead found in the wetland sediments at a high-profile federal site in New Jersey. Elevated lead concentrations have been detected across several transects of the wetlands with levels as high as 20,000 mg/kg historically. While the larger part of lead present in soils and sediments consists of insoluble species, the mobility of the lead in soluble forms, particularly Pb (II), poses the greatest environmental concern.
Several published studies have demonstrated the ability of the ZVI to reduce the oxidative state of dissolved Pb, thereby precipitating and preventing its migration and availability to down-gradient or down-stream receptors.
The 60-day treatability study created three sets of batch reactors using actual site sediments and water, with each set containing different dosages of ARS’ proprietary FEROXSM powder varying from 0% (control) to 4% and 15% of the sediment mass within the reactors. The reactors were analyzed for soluble lead and leachable lead on specific days after the initiation of the study. Soluble lead was based on the analysis of the dissolved phase lead in the decanted water while leachable lead was obtained by performing an extensive extraction procedure on the sediment solids. Results of the study to-date show highly encouraging results. Rapid reduction of leachable and soluble portions of the lead within the first two weeks of the start of the study. Halfway through the study, the leachable lead concentrations in both sets of reactors containing different dosages of iron have been reduced to below detection levels. Upon the completion of the study, ARS will produce a summary report for submission to the authorizing agency.
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