title: The inhibitory effects of reject water on nitrifying populations grown at different biofilm thickness.
abstract: 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.
authors.affiliation: Veolia Water Technologies AB - AnoxKaldnes, Klosterängsvägen 11A, SE-226 47 Lund, Sweden. Electronic address: maria.piculell@anoxkaldnes.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Piculell
authors.affiliation: Dept. of Chemistry and Molecular Biology/Microbiology, University of Gothenburg, Medicinaregatan 9E, SE-413 90 Gothenburg, Sweden.
authors.forename: Carolina
authors.initials: C
authors.lastname: Suarez
authors.affiliation: Water Chemistry and Water Technology, Engler-Bunte-Institut, Karlsruhe Institute of Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.affiliation: Veolia Water Technologies AB - AnoxKaldnes, Klosterängsvägen 11A, SE-226 47 Lund, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Christensson
authors.affiliation: Water Environment Technology, Dept. of Civil and Environmental Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
authors.forename: Frank
authors.initials: F
authors.lastname: Persson
authors.affiliation: Water Chemistry and Water Technology, Engler-Bunte-Institut, Karlsruhe Institute of Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Wagner
authors.affiliation: Dept. of Chemistry and Molecular Biology/Microbiology, University of Gothenburg, Medicinaregatan 9E, SE-413 90 Gothenburg, Sweden.
authors.forename: Malte
authors.initials: M
authors.lastname: Hermansson
authors.affiliation: Water and Environmental Engineering, Dept. of Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Jönsson
authors.affiliation: Veolia Water Technologies AB - AnoxKaldnes, Klosterängsvägen 11A, SE-226 47 Lund, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Welander
mesh_terms: D001419:Bacteria; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D058465:Nitrification; D009573:Nitrites; D014867:Water
chemical_list: D009573:Nitrites; D014867:Water
keywords: Biofilm thickness; FISH-CLSM; MBBR; NOB inhibition; Nitritation-anammox; Optical coherence tomography