Improvement of the settling properties of Anammox sludge in an SBR

Ana Dapena-Mora, Belén Arrojo, José Luis Campos, Anuska Mosquera-Corral, Ramón Méndez

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Biological systems for the treatment of wastewater have to provide optimum sludge retention to achieve high removal efficiencies. In the case of slow-growing micro-organisms, such as anaerobic ammonia-oxidizing (Anammox) bacteria, episodes of flotation involving biomass wash-out are especially critical. In this study a strategy based on the introduction of a mix period in the operational cycle of the Anammox Sequencing Batch Reactor (SBR) was tested for its effects on biomass retention and nitrite removal. Using this new cycle distribution the biomass retention inside the reactor improved as the solids concentration in the effluent of the SBR decreased from 20-45 to 5-10 mg VSS dm-3 and the biomass concentration inside the reactor increased from 1.30 to 2.53 g VSS dm-3 in a period of 25 days. A decrease of the sludge volume index (SVI) from 108 to 60 cm3 g VSS-1 was also observed. Complete depletion of nitrite was achieved in the reactor only with the new cycle distribution treating nitrogen loading rates (g N-NO2 - + g N-NH4+ dm-3 d-1) up to 0.60 g N dm-3 d-1.

Original languageEnglish
Pages (from-to)1417-1420
Number of pages4
JournalJournal of Chemical Technology and Biotechnology
Issue number12
StatePublished - Dec 2004
Externally publishedYes


  • Anammox
  • Biomass retention
  • Effluent quality
  • Mix period
  • Sequencing Batch Reactor (SBR)
  • Settling properties


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