Land application is becoming the more appropriate option for the final disposal of sewage sludge from wastewater treatment plants.However,the presence of heavy metals such as zinc,copper,chromium,cadmium and lead at levels higher than the recommended levels is always one of the major obstacles to its general use.Reduction of heavy metals in sewage sludge through source control is relatively expensive and impractical.Therefore,removal of heavy metals prior to land application has led to the development of ch...