Assessment of zero‐valent iron as a permeable reactive barrier for long‐term removal of arsenic compounds from synthetic water

Abstract

Zero‐valent iron (ZVI) has great potential to be used as a remediation material for the removal of a wide range of pollutants from groundwater. The present study assessed the potential of ZVI for arsenic remediation by investigating (i) the removal kinetics of arsenic by ZVI in a batch reactor and (ii) the longevity of ZVI to remove arsenic in a flow‐through column system which mimics the permeable reactive barrier (PRB) technology. Results of the batch experiments showed an effective removal (99.5%) of arsenic compounds from the synthetic water samples. Based on our kinetic study, the arsenic removals are expected to occur in a timescale of less than a few hours in typical PRB treatment conditions using ZVI (e.g. [ZVI] > 20 g/L and [As] < 1 mg/L). The flow‐through columns were continuously operated for 360 days at a flow rate of 2 mL/h. Samples were taken at regular intervals (90, 150, 230 and 360 days) and analysed for total arsenic concentration. The removal rates decreased by (45% in aerobic and 39% in anoxic) after 360 days of operation indicate that the regular replacement of the reactive material would be required for efficient removal of arsenic.

Keywords:

• arsenic adsorption
• groundwater remediation
• oxidation
• permeable reactive barrier
• zero‐valent iron

Acknowledgements

This research was supported by research funds of Chonbuk National University in 2007. The preparation of this manuscript was partly supported by Grant R01‐2006‐000‐10491‐0 from the Basic Research Program of the KOSEF. Seralathan Kamala‐Kannan is grateful to the Chonbuk National University for the Postdoctoral grant (second term of 2007).