Electrokinetic-enhanced remediation of actual arsenic-contaminated soils with approaching cathode and Fe0 permeable reactive barrier
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The aim of this study was to investigate the remediation efficiency of actual arsenic-contaminated soils by electrokinetic (EK)-enhanced remediation with approaching cathode and Fe0 permeable reactive barrier (PRB).
Materials and methods
Experiments were conducted in a lab-made apparatus consisting of the anode reservoir, the soil specimen chamber, and the cathode reservoir.
Results and discussion
In this study, the enhanced combination methods (approaching cathode and Fe0-PRB) were assisted for EK remediation of actual arsenic-contaminated soils under a voltage gradient of 1 V/cm and a treatment period of 96 h. Experimental results showed that arsenic accumulated in the anode sections (I, II) of the soil by employing EK alone with an arsenic removal rate of less than 5%. In contrast, EK-enhanced remediation with either approaching cathode (EK/AC) or Fe0-PRB (EK/PRB) reduced the arsenic concentrations in both central and anode sections of the soil and afforded the removal rates of 20% in both cases. However, EK-enhanced remediation with the combination of approaching cathode and Fe0-PRB (EK/PRB/AC) reached the removal efficiency of 45% without arsenic accumulation in any soil sections. This phenomenon is mainly caused by the approaching cathode that creates an alkaline environment to promote the migration of arsenic, as well as PRB filled with Fe0 that achieves the adsorption and immobilization of arsenic.
The highest remediation efficiency was achieved in the EK/PRB/AC test, which was attributed to the fact that the combination of this two methods solved the problem of arsenic accumulation in treated soil and ensured a more thorough arsenic removal. Furthermore, enhanced remediation efficiency does not elevate the costs.
KeywordsApproaching cathode Arsenic-contaminated soil Electrokinetic remediation Permeable reactive barriers Zero-valent iron
This work was financially supported by the National Key R&D Program of China (No. 2018YFD0800700), Natural Science Foundation of Guangdong Province (No. 2015A030308008), Guangdong Province Science and Technology Planning Project (No. 2018A050506046), 2019 Science and Technology innovation and popularizing, 2017 innovation team of Guangdong regular college (No. 2017GKCXTD004), Shaoguan City Science and Technology Special Project (No. 2017sgtyfz102), and Foshan City Science and Technology Innovation Project (No. 2017AB003952, No. 2017AG10072, No. 2016AG100522, No. 2016AG100482).
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