Optimization of Fe2+/solids content ratio for a novel sludge heavy metal bioleaching process

Jonathan W C WONG*, X. Y. Gu

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

16 Citations (Scopus)


A novel bioleaching process, preincubation bioleaching (PB) has been recently developed in our laboratory for decontamination of heavy-metal-laden sewage sludge by removing the toxic low molecular weight organic acids using an isolated degradative yeast species. The objective of the present study was to optimize Fe2+/solids content ratio required for removing heavy metals from sewage sludge by using this novel process at high solids content. Results from the present study showed that regardless of the Fe2+/solids content ratio iron oxidation and sludge acidification could be achieved within 2 days confirming the effectiveness of PB in reducing the inhibitory organic acids. When PB was conducted at an elevated solids content of 3%, Fe2+/solids content ratio could be reduced to 0.75:1, 1:1 and 1.25:1 for solubilization of Zn, Cu and Cr respectively. Under this optimized bioleaching conditions, the following solubilization efficiencies were obtained after 8 days of bioleaching: 100% Zn, 96% Cu, 60% Cr with no reduction in nutrient contents. Hence, bioleaching at elevated solids contents represents a more economical way for decontamination of heavy-metal-laden sewage sludge while preserving its fertility values.

Original languageEnglish
Pages (from-to)445-450
Number of pages6
JournalWater Science and Technology
Issue number3
Publication statusPublished - 2008

Scopus Subject Areas

  • Environmental Engineering
  • Water Science and Technology

User-Defined Keywords

  • Acidithiobacillus ferrooxidans
  • Bioleaching
  • Heavy metals
  • Sewage sludge


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