Effects of trace levels of copper, chromium, and zinc ions on the performance of activated sludge

S. N. Sin, H. Chua, Wai Hung Lo, P. H.F. Yu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

12 Citations (Scopus)


The effects of copper, chromium, and zinc ions, at trace levels, on the performance of a simulated activated sludge process were investigated. The results of batch adsorption experiments showed that the adsorption of copper, chromium, and zinc ions followed both the Langmuir and Freundlich isotherms. The presence of trace levels of these three metals not only reduced the adsorption rate of organic matters but also the chemical oxygen demand adsorption capacity (CAC) of the activated sludge. Metal ions competed with the organic substrate for adsorption binding sites on the surfaces of activated sludge bioflocs and reduced the CAC. Studies performed in a sequential batch reactor (SBR) showed that the presence of trace levels of heavy metal ions in wastewater affected the SBR performance to different extents depending on the hydraulic retention time (HRT). When the reactors were operated at short HRTs of 2.5 d or less, the presence of trace levels of heavy metal ions reduced substantially the CAC of activated sludge, which, in turn, affected significantly the performance of the SBR. However, under longer HRTs (e.g., 5d), the heavy metal ions in the wastewater reduced the CAC but had no significant effect on the chemical oxygen demand removal efficiency.
Original languageEnglish
Pages (from-to)487-500
Number of pages14
JournalApplied Biochemistry and Biotechnology - Part A Enzyme Engineering and Biotechnology
Publication statusPublished - 1 Jan 2000


  • Activated sludge
  • Adsorption capacity
  • Chemical oxygen demand removal
  • Heavy metals
  • Sequencing batch reactor

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology

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