Comparative Study on Physical and Chemical Characteristics of Sludge Vermicomposted by Eisenia Fetida

Prior to vermicompost application to the soils, there is a need to determine the heavy metal concentrations in the final vermicomposts. This study was designed to evaluate the effects of earthworm activity on heavy metals in sewage sludge. Com-pared with before vermicomposting by Eisenia fetida, the results are as follows: (1) water content, the pH value and organic matter content decreased, (2) total nitrogen content increased, total phosphorus content, total potassium content decreased, (3) available nitrogen concentration, available phosphorus content increased and, (4) the total content of five metals (Cu, Ni, Cd, Pb and Zn) decreased, and the bioaccumulation factor (BAF) shows that vermicomposting can efficiently remove heavy metals. Therefore, it can be concluded that the soil use of sludge of the Wastewater Treatment Plant in Huaibei is feasible.