Characterization of an indigenous iron-oxidizing bacterium and its effectiveness in bioleaching heavy metals from anaerobically digested sewage sludge

Xiangyang Gu, Jonathan W C WONG*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

The objective of the present study was to isolate the indigenous iron-oxidizing bacterium and compare its effectiveness in bioleaching of heavy metals from fresh anaerobically digested sludge and aged sludge which had undergone a storage period in a sludge holding tank. An acidophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans strain ANYL-1 was successfully isolated from the sludge collected from a wastewater treatment plant at Yuen Long district in Hong Kong. It was a Gram negative, non-motile rod shaped bacterium which used ferrous iron, elemental sulfur or thiosulfate as energy source, but did not utilize tetrathionate or glucose as energy source. The optimal temperature and pH for its growth and iron oxidation were 30-35°C and pH 2.0-2.5, respectively. When it was used in the bioleaching of anaerobically digested sewage sludge, an inhibition on metal solubilization was observed in fresh sludge except for Zn whose dissolution was solely a chemical process. Compared to the 3 and 4 days required for solubilization of Cu and Cr respectively from the sludge sample collected after the sludge holding tank (Sludge SHT), 6 days were required to bioleach Cu and Cr from fresh sludge (Sludge AD). The fresh sewage sludge posed an unfavorable condition for bioleaching of heavy metals from anaerobically digested sludge as reflected by the prolonged bioleaching time. Therefore, further studies were needed to understand the inhibitory effects in the fresh anaerobically digested sludge and develop measures to remove it in order to improve the heavy metal bioleaching efficiency.

Original languageEnglish
Pages (from-to)889-897
Number of pages9
JournalEnvironmental Technology (United Kingdom)
Volume25
Issue number8
DOIs
Publication statusPublished - 2004

Scopus Subject Areas

  • Environmental Chemistry
  • Water Science and Technology
  • Waste Management and Disposal

User-Defined Keywords

  • Acidithiobacillus ferrooxidans
  • Anaerobic digester
  • Heavy metals
  • Sewage sludge
  • Sludge holding tank

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