Zero-Valent Iron treatment of DNAPL
ARS recently completed a project in which treatability studies were performed using groundwater containing a TCE concentration of 362,000 µg/l and soil containing a TCE concentration of 290,400 µg/kg. A 52-day laboratory test was created to evaluate the effectiveness of FEROXSM powder to treat the high levels of high contaminant. Following the 52 days of treatment, 99% reduction of TCE in the batch reactors was observed. The results showed that the reduction of TCE approximates a first-order kinetic rate at the tested iron-to-TCE ratios. The study also demonstrated the dependence of reaction kinetics on iron dosage. Accordingly, higher dosages of FEROXSM resulted in a more rapid rate of TCE reduction. In addition, the higher iron dosages were more effective at controlling the accumulation of daughter products (ie. cis-1, 2-DCE) associated with the reduction of TCE. In summary, the data from this test confirmed FEROXSM successfully treats DNAPL-level concentrations of organic chemicals.
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