The objectives of this study were to investigate microbial reduction of perchlorate in the presence of zero-valent iron (ZVI) and to demonstrate the potential of this process to treat perchlorate-contaminated water. Perchlorate has been shown to be easily reducible by microorganisms
derived from a wastewater treatment plant in the presence of ZVI. In the batch experiment, the iron-mediated microbial culture completely removed 65 mg/L of perchlorate in 6 days and 16 mg/L of perchlroate was continuously removed from the column reactor over 20 days. The removal rate in the
batch reactor was similar to that observed with hydrogen gas (5%) or acetate (173 mg/L) replacing iron as an electron source. In contrast, perchlorate was not degraded to any significant extent in control reactors containing iron or culture only. These results suggest that zero-valet iron
provided an electron donor(s) for biological perchlorate reduction. Repeated spiking of perchlorate to a batch reactor containing both microorganisms and iron showed that complete perchlorate reduction by the iron-supported culture could be sustained. This study demonstrated the potential
application of zero-valent iron as an electron donor for microbial perchlorate reduction through batch and column experiments. Use of zero-valent iron may eliminate the need to continually supply electron donors such as organic substrates and the explosive hydrogen gas. In contrast to these
electron donors, iron is inexpensive, long lasting, safe to handle, and does not leave significant organic residuals in the treated water.
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