The inhibitory effects of reject water on nitrifying populations grown at different biofilm thickness

Research output: Contribution to journalArticle


Suppression of nitrite oxidizing bacteria (NOB) is of vital importance to achieve successful, energy efficient, mainstream anammox processes for wastewater treatment. In this study, biofilm carriers from a fully nitrifying MBBR system, fed with mainstream wastewater, were temporarily exposed to reject water from sludge dewatering, to evaluate this as a possible strategy to inhibit NOB and achieve nitrite production under realistic conditions. Two different carrier types were compared, in which biofilm thickness was maintained at approximately 400 and 50 μm, respectively, and reject treatment was tested at different exposure time and loading rates. Reject exposure almost always resulted in an increased nitrite production in the thinner biofilm, and overall, nitrifiers growing in the thin biofilm were more sensitive than those grown in the thicker biofilm. The effect from reject exposure remained in the systems for four days after returning to mainstream operation, with nitrite production gradually increasing for three days. Increased concentrations of free ammonia correlated with reject exposure and may be the cause of inhibition, although other factors cannot be excluded.


  • Maria Piculell
  • Carolina Suarez
  • Chunyan Li
  • Magnus Christensson
  • Frank Persson
  • Michael Wagner
  • Malte Hermansson
  • Karin Jönsson
  • Thomas Welander
External organisations
  • Karlsruhe Institute of Technology
  • Hydrotech Veolia Water Solutions and Technologies AB
  • University of Gothenburg
  • Chalmers University of Technology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Water Engineering


  • Biofilm thickness, FISH-CLSM, MBBR, Nitritation-anammox, NOB inhibition, Optical coherence tomography
Original languageEnglish
Pages (from-to)292-302
Number of pages11
JournalWater Research
Publication statusPublished - 2016 Nov 1
Publication categoryResearch