Treatment of Dissolved Perchlorate, Nitrate, and Sulfate Using Zero-Valent Iron and Organic Carbon
- YingYing Liu,
- Carol J. Ptacek * and
- David W. Blowes
Waters containing ClO4− and dissolved NO3−, derived from detonated explosives and solid propellants, often also contain elevated concentrations of other dissolved constituents, including SO42−. Four column experiments, containing mixtures of silica sand, zero-valent Fe (ZVI) and organic C (OC) were conducted to evaluate the potential for simultaneous removal of NO3−, SO42− and ClO4−. Initially, the flow rate was maintained at 0.5 pore volumes (PV) d−1 and then decreased to 0.1 PV d−1 after 100 PV of flow. Nitrate concentrations decreased from 10.8 mg L−1 (NO3–N) to trace levels through NO3− reduction to NH4+ using ZVI alone and through denitrification using OC. Observations from the mixture of ZVI and OC suggest a combination of NO3− reduction and denitrification. Up to 71% of input SO42− (24.5 ± 3.5 mg L−1) was removed in the column containing OC, and >99.7% of the input ClO4− (857 ± 63 μg L−1) was removed by the OC- and (ZVI + OC)-containing columns as the flow rate was maintained at 0.1 PV d−1. Nitrate and ClO4− removal followed first-order and zero-order rates, respectively. Nitrate >2 mg L−1 (NO3–N) inhibited ClO4− removal in the OC-containing column but not in the (ZVI + OC)-containing column. Sulfate did not inhibit ClO4− degradation within any of the columns.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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