The inhibitory effects of reject water on nitrifying populations grown at different biofilm thickness
Journal article, 2016

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 mm, 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.


Biofilm thickness

Optical coherence tomography



NOB inhibition


Maria Piculell

Veolia Water Technologies AB

Carolina Suarez

University of Gothenburg

Chunyan Li

Karlsruhe Institute of Technology (KIT)

Magnus Christensson

Veolia Water Technologies AB

Frank Persson

Chalmers, Civil and Environmental Engineering, Water Environment Technology

Michael Wagner

Karlsruhe Institute of Technology (KIT)

Malte Hermansson

University of Gothenburg

Karin Jönsson

Lund University

Thomas Welander

Veolia Water Technologies AB

Water Research

0043-1354 (ISSN) 1879-2448 (eISSN)

Vol. 104 1 Nov 292-302

Areas of Advance

Building Futures (2010-2018)

Subject Categories

Water Engineering


Water Treatment


Basic sciences



More information

Latest update

4/9/2018 1