Mechanism of heavy-metal removal by activated sludge

F. Pagnanelli, S. Mainelli, L. Bornoroni, D. Dionisi, L. Toro

Research output: Contribution to journalArticlepeer-review

83 Citations (Scopus)


This paper investigates the chemical mechanisms operating in cadmium and lead removal by activatedsludge in sequencing batch reactors. Selective extraction and acid digestion of sludge samples denoted that both Cd and Pb are mainly present as surface-bound metals. Characterisation of sludge samples by potentiometric titrations and IR spectra suggested that carboxylic and amino groups are the main active sites responsible for the binding properties of the biomass. Simulation of metal speciation implemented with complexation constants determined in biosorption tests, showed that cadmium predominates as biosorbed species, while lead was mainly removed by precipitation.
Original languageEnglish
Pages (from-to)1028-1034
Number of pages7
Issue number8
Publication statusPublished - May 2009


  • bisorption
  • heavy metals
  • activated sludge
  • potentiometric titration
  • metal speciation


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