Removal of heavy metals from sewage sludge with a combination of bioleaching and electrokinetic remediation technology

The combination of bioleaching and electrokinetic remediation has been proved to be an effective method to remove heavy metals from municipal sewage sludge. The results showed that using electrokinetic remediation for six days after bioleaching for four days, the contents of Cu and Zn in sewage sludge decreased from 296.4 mg kg(-1) and 3756.2 mg kg(-1) to 63.4 mg kg(-1) and 33.3 mg kg(-1), respectively, which could meet the Chinese standard for land application of the heavy metals in sewage sludge. During the bioleaching process, both the organic sulfide fraction of Cu and the carbonate-bound and organic sulfide fractions of Zn transformed to soluble and ionic fractions which could easily migrate to the electrode zone and then accumulate there. Finally, the soluble and ionic fractions of these heavy metals could be disposed of or recycled expediently at the end of electrokinetic remediation. (C) 2010 Elsevier B.V. All rights reserved.