Coupling Electrokinetics with Permeable Reactive Barriers of Zero-Valent Iron for Treating a Chromium Contaminated Soil

Abstract

Electrokinetic (EK) remediation coupled with permeable reactive barriers (PRB) of zero-valent iron (ZVI) was applied for treating a Cr contaminated soil. Results show that loading ZVI-PRBs in different locations of soil column strongly affected the EK performance. Transport of Cr in the soil column was resulted from the balance of its electromigration and electroosmosis (EO). With increasing treatment time, the total Cr concentration of the soil column pore-water decreased in all the treatments. The lowest Cr concentration of the pore-water decreased to only 0.03 mg L⁻¹ after a run for 384 h, and a maximum 71.5% of initial soil Cr(VI) was removed when two ZVI-PRBs were loaded at the two ends of the soil column. Additionally, the soil EC values were lower than the original one after the EK-PRB treatments, suggesting that these treatments did not introduce more ions into the soil.

Keywords:

• Chromium
• electrokinetic
• permeable reactive barrier
• soil
• zero-valent iron

ACKNOWLEDGEMENTS

This study was supported by the National Natural Science Foundation of China (20807044) and the State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences.

Notes

∗Soil column labeled as Region I ∼ V from anode to cathode.

Note: “/” shows the location of ZVI-PRB.

Note: “bd” means the content below the detection limit. Mass balance (%) = (Total soil Cr mass after treatments + Total Cr mass in PRB + Total Cr mass of soil pore-water from soil column) × 100/Initial Cr mass in soil.

Note: “/” shows the location of ZVI-PRB.