Enhanced Stabilization of Cu and Zn in the Sediments by Montmorillonite for the Management of Heavy Metal-Contaminated Municipal Sludge

The adsorption, desorption and species distribution characteristics of Cu and Zn in the sediments with or without montmorillonite spiked were investigated by isothermal adsorption and sequential extraction procedure. The results show that the montmorillonite spiked in the sediments enhanced the adsorption capacity of sediments for Cu and Zn and facilitated the transformation of Cu and Zn from less stable phases to more stable phases, especially advanced the translation of Cu and Zn from exchangeable fraction to the other fractions. Meanwhile, the montmorillonite inserted in the sediments restrained Cu and Zn leached from the sediments. These results imply that the addition of montmorillonite to the sediments facilitated the stability of heavy metals in the sediments and restrained the environmental risk of heavy metals to the aquatic environment to some extent.