Stratification of nitrifier guilds in granular sludge in relation to nitritation
Soler-Jofra, Aina (Delft University of Technology. Department of Biotechnology)
Wang, Ru (Delft University of Technology. Department of Biotechnology)
Kleerebezem, Robbert (Delft University of Technology. Department of Biotechnology)
van Loosdrecht, Mark (Delft University of Technology. Department of Biotechnology)
Pérez Cañestro, Julio (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)

Date:	2019
Abstract:	A lab-scale partial nitritation granular sludge air-lift reactor was operated in continuous mode treating low strength synthetic medium (influent ca. 50 mg-N-NH /L). Granules were initially stratified with AOB in the external shell and NOB in the inner core at 20 °C. Once temperature was decreased progressively from 20 °C to 15 °C, nitrate production was initially observed during several weeks. However, by maintaining relatively high ammonium concentrations in the liquid (ca. 28 mg-N-NH /L), effluent nitrate concentrations in the reactor decreased in time and process performance was recovered. Batch tests were performed in the reactor at different conditions. To understand the experimental results an existing one-dimensional biofilm model was used to simulate batch tests and theoretically assess the impact of stratification, dissolved oxygen (DO) and short-term effects of temperature on time course concentrations of ammonium, nitrite and nitrate. This theoretical assessment served to develop an experimental methodology for the evaluation of in-situ batch tests in the partial nitritation reactor. These batch tests proved to be a powerful tool to easily monitor the extent of stratification of nitrifier guilds in granular sludge and to determine the required bulk ammonium concentration to minimize nitrite oxidation. When nitrifier guilds were stratified in the granular sludge, a higher bulk ammonium concentration was required to efficiently repress NOB at lower temperature (ca. 19 versus 7 mg-N-NH /L at 15 and 20 °C, respectively).
Grants:	Ministerio de Economía y Competitividad CTQ2017-82404-R
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Partial nitrification ; Temperature ; Nitrate-oxidizing bacteria repression ; Residual ammonium concentration ; Biofilm
Published in:	Water Research, Vol. 148 (January 2019) , p. 479-491, ISSN 1879-2448

DOI: 10.1016/j.watres.2018.10.064
PMID: 30408734

13 p, 2.3 MB

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