Effect of influent COD/SO42- ratios on UASB treatment of a synthetic sulfate-containing wastewater

Yong Hu, Zhaoqian Jing, Yuta Sudo, Qigui Niu, Jingru Du, Jiang Wu, Yu You Li

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95 Citations (Scopus)


The effect of the chemical oxygen demand/sulfate (COD/SO42-) ratio on the anaerobic treatment of synthetic chemical wastewater containing acetate, ethanol, and sulfate, was investigated using a UASB reactor. The experimental results show that at a COD/SO42- ratio of 20 and a COD loading rate of 25.2gCODL-1d-1, a COD removal of as high as 87.8% was maintained. At a COD/SO42- ratio of 0.5 (sulfate concentration 6000mgL-1), however, the COD removal was 79.2% and the methane yield was 0.20LCH4gCOD-1. The conversion of influent COD to methane dropped from 80.5% to 54.4% as the COD/SO42- ratio decreased from 20 to 0.5. At all the COD/SO42- ratios applied, over 79.4% of the total electron flow was utilized by methane-producing archaea (MPA), indicating that methane fermentation was the predominant reaction. The majority of the methane was produced by acetoclastic MPA at high COD/SO42- ratios and both acetoclastic and hydrogenthrophic MPA at low COD/SO42- ratios. Only at low COD/SO42- ratios were SRB species such as Desulfovibrio found to play a key role in ethanol degradation, whereas all the SRB species were found to be incomplete oxidizers at both high and low COD/SO42- ratios.

Original languageEnglish
Pages (from-to)24-33
Number of pages10
Publication statusPublished - 2015 Jul 1


  • COD/SO ratio
  • Chemical wastewater
  • Methane production
  • Sulfate
  • Sulfate reduction
  • UASB

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Pollution
  • Chemistry(all)
  • Health, Toxicology and Mutagenesis
  • Environmental Engineering
  • Environmental Chemistry


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