The treatment of iron oxalate leach liquors in a UASB with sulfate reduction

J. E. Teer, D. J. Leak, A. W.L. Dudeney, A. Narayanan, D. C. Stuckey

Research output: Contribution to journalConference articlepeer-review

7 Citations (SciVal)


The presence of small amounts of iron (> 0.013% Fe) in sand creates problems in the manufacture of high quality glass. Removal by hot sulphuric acid is possible, but creates environmental problems, and is costly. Hence organic acids such as oxalic have been investigated since they are effective in removing iron, and can be degraded anaerobically. The aim of this work was to identify key intermediates in the anaerobic degradation of oxalate in an upflow anaerobic sludge blanket reactor (UASB) which was removing iron from solution in the sulphide form, and to determine the bacterial species involved. 2-bromoethanesulfonic acid (BES) and molybdenum were selected as suitable inhibitors for methanogenic and sulphate reducing bacteria (SRB) respectively. 40 mM molybdenum was used to inhibit the SRB in a reactor with a 12 hr HRT. Total SRB inhibition took place in 20 hrs, with a complete breakthrough of influent sulphate. The lack of an immediate oxalate breakthrough confirmed Desulfovibrio vulgaris subspecies oxamicus was not the predominant oxalate utilising species. Nevertheless, high concentrations of molybdenum were found to inhibit oxalate utilising bacteria in granular reactors but not in suspended population reactors; this observation was puzzling, and at present cannot be explained. Based on the intermediates identified, it was postulated that oxalate was degraded to formate by an oxalate utilising bacteria such as Oxalobacter formigenes, and the formate used by the SRBs to reduce sulphate. Acetate, as a minor intermediate, existed primarily as a source of cell carbon for oxalate utilising bacteria. Methanogenic inhibition identified that 62% of the CH4 in the reactor operated at 37°C originated from hydrogenotrophic methanogenesis, whilst this figure was 80% at 20°C. Possible irreversible effects were recorded with hydrogenotrophic methanogens.

Original languageEnglish
Pages (from-to)383-390
Number of pages8
JournalWater Science and Technology
Issue number6-7
Publication statusPublished - 17 Dec 1997
EventProceedings of the 1997 8th IAWQ International Conference on Anaerobic Digestion - Sendai, Jpn
Duration: 25 May 199729 May 1997


  • Ferrous precipitation
  • Inhibition
  • Oxalate degradation
  • Sulphate reduction
  • UASB

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


Dive into the research topics of 'The treatment of iron oxalate leach liquors in a UASB with sulfate reduction'. Together they form a unique fingerprint.

Cite this