This work was conducted to evaluate the effects of vermicomposting on the speciation and mobility of
heavy metals (Zn, Pb, Cr, and Cu) in cattle dung (CD) and pig manure (PM) using tessier sequential extraction
method. Results showed that the pH, total organic carbon and C/N ratio were reduced, while the electric
conductivity and humic acid increased after 90 days vermicomposting. Moreover, the addition of
earthworm could accelerate organic stabilization in vermicomposting. The total heavy metals in final vermicompost
from CD and PM were higher than the initial values and the control without worms.
Sequential extraction indicated that vermicomposting decreased the migration and availability of heavy
metals, and the earthworm could reduce the mobile fraction, while increase the stable fraction of heavy
metals. Furthermore, these results indicated that vermicomposting played a positive role in stabilizing
heavy metals in the treatment of animal manure.