Synergistic remediation of lead contaminated soil by microbial fuel cell and composite remediation agent

Abstract

Microbial fuel cell (MFC) could uses microorganisms to convert the solid wastes into electrical energy. Lead contaminated soil was remediated in MFC through internal electric field reduction, where Pb(II) was reduced to Pb produced on the cathode. When the composite remediation agents of MgO, Ca(H2PO4)2and montmorillonite were added to the soil, Pb can be solidified and adsorbed in the soil, which reduces the toxicity of lead leaching in the soil and makes Pb exist stably in the soil. After synergistic bioremediation, the Pb concentration was decreased by 374.62 mg/kg, whereas Pb in the acetic acid extractable state was mainly transformed into that in reducible state oxidizable state and residue state. Pb removal efficiency of contaminated soil at pH of 5 was the highest of 22.28% after remediation. The Pb removal efficiency at 10 g/kg Pb was 21.02%. The proportion of acetic acid extracted was decreased by 24.26%∼32.36%, 20.54%∼28.69%, and 34.09∼42.78% at the initial lead concentration of 2.5 g/kg, 5 g/kg and 10 g/kg, respectively. The proportion of extractable acetic acid in 10 g/kg Pb contaminated soil was decreased most, converting to oxidizable state (increased by 18.50%∼22.79%) and residue state (increased by 10.57%∼21.10%). This study provides alternative technology for the remediation of Pb contaminated soil in high concentration.

Keywords

• Microbial fuel cell
• Lead contaminated soil
• Magnesium oxide
• Monocalcium phosphate
• Montmorillonite