Effects of electron acceptors on sulphate reduction activity in activated sludge processes

Francisco Rubio-Rincón, Carlos Lopez-Vazquez, Laurens Welles, Tessa van den Brand, Ben Abbas, Mark van Loosdrecht, Damir Brdjanovic

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)
206 Downloads (Pure)

Abstract

The concentration of sulphate present in wastewater can vary from 10 to 500 mg SO4 2−/L. During anaerobic conditions, sulphate is reduced to sulphide by sulphate-reducing bacteria (SRB). Sulphide generation is undesired in wastewater treatment plants (WWTPs). Previous research indicated that SRB are inhibited by the presence of electron acceptors (such as O2, NO3 and NO2). However, the contact times and concentrations used in those studies are by far higher than occur in WWTPs. Since sulphide can influence the biological nitrogen and phosphorus removal processes, this research aimed to understand how the different electron acceptors commonly present in biological nutrient removal (BNR) systems can affect the proliferation of SRB. For this purpose, a culture of SRB was enriched in a sequencing batch reactor (approx. 88% of the total bacteria population). Once enriched, the SRB were exposed for 2 h to typical concentrations of electron acceptors like those observed in BNR systems. Their activity was assessed using three different types of electron donors (acetate, propionate and lactate). Oxygen was the most inhibiting electron acceptor regardless the carbon source used. After exposure to oxygen and when feeding acetate, an inactivation time in the sulphate reduction activity was observed for 1.75 h. Once the sulphate reduction activity resumed, only 60% of the original activity was recovered. It is suggested that the proliferation of SRB is most likely to occur in BNR plants with an anaerobic fraction higher than 15% and operating at sludge retention times higher than 20 days (at a temperature of 20 °C). These results can be used to implement strategies to control the growth of sulphate reducers that might compete for organic carbon with phosphate-accumulating organisms.

Original languageEnglish
Pages (from-to)6229-6240
Number of pages12
JournalApplied Microbiology and Biotechnology
Volume101
Issue number15
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • Biological nutrients removal
  • Electron acceptor inhibition
  • Sulphate reduction activity
  • Sulphate-reducing bacteria
  • Wastewater treatment

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