Reducing the heavy metal content of sewage sludge by advanced sludge treatment methods

R Dewil, Jan Baeyens, E Neyens

Research output: Contribution to journalArticle

31 Citations (Scopus)


Waste-activated sludge (WAS) processes are key technologies to treat wastewater: their effluents can meet stringent discharge standards, thus ensuring a minimum residual impact on the aquatic environment. The presence of heavy metals in the excess sludge poses, however, serious problems, and considerably hampers the final disposal alternatives, especially in the agricultural use (soil improvement/amendment). This article studies the effect of thermal hydrolysis and Fenton's peroxidation on the heavy metal content of the dewatered sludge. Acid thermal hydrolysis reduces the heavy metal content in the filter cake except for Cu, Hg, and Pb. Alkaline thermal hydrolysis releases Cu, Pb, and Cr. Fenton's peroxidation transfers Cd, Cu, and Ni from the filter cake into the filtrate. Land application of the residual cake can hence be reconsidered.
Original languageEnglish
Pages (from-to)990-995
Number of pages6
JournalEnvironmental Engineering Science
Issue number6
Publication statusPublished - 1 Jan 2006


  • sludge
  • hydrolysis
  • peroxidation
  • heavy metals


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