Fate of metals before and after chemical extraction of incinerated sewage sludge ash

Jiang shan Li, Daniel C.W. Tsang, Qi ming Wang, Le Fang, Qiang Xue, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

29 Citations (Scopus)


This study investigated the changes of the leaching potential and distribution of metals in the chemically extracted ISSA. Batch extraction experiments with different extractants, including inorganic acids, organic acids, and chelating agents, were conducted on the ISSA collected from a local sewage sludge incinerator. The extraction of Zn, Cu, Pb, Ni, Cd, Ba, Cr and As from the ISSA and the corresponding changes of the mobility and speciation were examined. The results showed that the metals in ISSA were naturally stable because large portions of metals were associated with the residual fraction. The inorganic (HNO3and H2SO4) and organic acids (citric acid and oxalic acid) significantly co-dissolved the metals through acid dissolution, but the reduction in the total concentrations did not tally the leaching potential of the residual metals. The increase in the exchangeable fraction due to destabilization by the extractants significantly enhanced the mobility and leachability of the metals in the residual ISSA. Chelating agents (EDTA and EDTMP) only extracted a small quantity of metals and had a marginal effect on the fate of the residual metals, but they significantly reduced the Fe/Mn oxide-bound fraction. In comparison, the bioaccessibility of residual metals were reduced to varying extent. Therefore, the disposal or reuse of chemically extracted ISSA should be carefully evaluated in view of possible increase in mobility of residual metals in the environment.
Original languageEnglish
Pages (from-to)350-359
Number of pages10
Publication statusPublished - 1 Jan 2017


  • Bioaccessibility
  • Chemical extraction
  • Heavy metals
  • Incinerator ash
  • Mobility
  • Sewage sludge

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry


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