Aluminum drinking water treatment residuals (Al-WTRs) as an entrapping zone for lead in soil by electrokinetic remediation

The usefulness of the combined electrokinetic (EK) remediation with aluminum drinking water treatment residuals (Al-WTRs) as an entrapping zone (EZ) for removal of lead ion from artificially contaminated soil was demonstrated. Laboratory experiments were performed with variable conditions including (i) type of Al-WTRs materials and the application of Al-WTRs as an EZ system during the EK processing, (ii) pH and (iii) position of EZ in the soil cell. The potential of aluminum leachability from Al-WTRs as the result of EK process was also discussed. The results show that the lead ions in the contaminated soil were transferred into the EZ by EK process and immobilized by adsorption sites on polymeric aluminum residual in the Al-WTRs. These residual compounds contained lead, which were not dissolved by diluted organic acid (0.1 M acetate buffer), were retained in the EZ and accumulated there. After 72 h of the electrokinetic process, the total amount of lead in the EZ was much higher than the initial lead concentration in the contaminated soil.

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► Combined electrokinetic (EK) remediation with aluminum drinking water treatment residuals (Al-WTRs) as an entrapping zone (EZ) for removal of lead ion from kaolinite clay soil.
► Lead ions in the contaminated kaolinite clay were transferred into the EZ by EK process and immobilized by the adsorption sites on the Al-WTRs.
► A relatively high lead ions entrapping in EK/EZ system was achieved by using Miyamachi sludge as than that by Nishino sludge.
► Installed Al-WTRs materials in the EK/EZ system was safe under the base condition, e.g. near the cathode side, where the leaching aluminum concentration was ca. 0.02 mg/g.