Adaptation of granular sludge microbial communities to nitrate, sulfide, and/or p-cresol removal

Nuria Fernandez-Gonzalez, Reyes Sierra-Alvarez, James A. Field, Ricardo Amils, Jose Luis Sanz

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Effluents from petroleum refineries contain a toxic mixture of sulfide, nitrogen, and phenolic compounds that require adequate treatment for their removal. Biological denitrification processes are a cost-effective option for the treatment of these effluents, but the knowledge on the microbial interactions in simultaneous sulfide and phenol oxidation in denitrifying reactors is still very limited. In this work, microbial community structure and macrostructure of granular biomass were studied in three denitrifying reactors treating a mixture of inorganic (sulfide) and organic (p-cresol) electron donors for their simultaneous removal. The differences in the available substrates resulted in different community assemblies that supported high removal efficiencies, indicating the community adaptation capacity to the fluctuating compositions of industrial effluents. The three reactors were dominated by nitrate reducing and denitrifying bacteria where Thiobacillus spp. were the prevalent denitrifying organisms. The toxicity and lack of adequate substrates caused the endogenous decay of the biomass, leading to release of organic matter that maintained a diverse although not very abundant group of heterotrophs. The endogenous digestion of the granules caused the degradation of its macrostructure, which should be considered to further develop the denitrification process in sulfur-based granular reactors for treatment of industrial wastewater with toxic compounds.

Original languageEnglish (US)
Pages (from-to)305-316
Number of pages12
JournalInternational Microbiology
Issue number3
StatePublished - Sep 19 2019


  • Endogenous decay
  • Granular denitrifying reactor
  • Hazardous waste
  • Nitrogen transformations
  • Petroleum refinery wastewater
  • Thiobacillus

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)


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