Record nummer 2219989
Titel artikel Effects of the residual ammonium concentration on NOB repression during partial nitritation with granular sludge
Auteur(s) Poot, V. ; Hoekstra, M. ; Geleijnse, M.A.A. ; Loosdrecht, M.C.M. van ; Pérez, J.
Tijdschrifttitel Water research : the journal of the International Association on Water Quality
Deel(Jaar)Nummer (2016)106
Paginering 518 - 530
Online full text
Publicatie type Artikel
Taal Engels
Toelichting Partial nitritation was stably achieved in a bench-scale airlift reactor (1.5L) containing granular sludge. Continuous operation at 20 °C treating low-strength synthetic wastewater (50 mg N-NH4+/L and no COD) achieved nitrogen loading rates of 0.8 g N-NH4+/(L·d) during partial nitritation. The switch between nitrite-oxidizing bacteria (NOB) repression and NOB proliferation was observed when ammonium concentrations in the reactor were below 2–5 mg N-NH4+/L for DO concentrations lower than 4 mg O2/L at 20 °C. Nitrospira spp. were detected to be the dominant NOB population during the entire reactor operation, whereas Nitrobacter spp. were found to be increasing in numbers over time. Stratification of the granule structure, with ammonia-oxidizing bacteria (AOB) occupying the outer shell, was found to be highly important in the repression of NOB in the long term. The pH gradient in the granule, containing a pH difference of ca. 0.4 between the granule surface and the granule centre, creates a decreasing gradient of ammonia towards the centre of the granule. Higher residual ammonium concentration enhances the ammonium oxidation rate of those cells located further away from the granule surface, where the competition for oxygen between AOB and NOB is more important, and it contributes to the stratification of both populations in the biofilm.
Betrokken instanties Technische Universiteit Delft
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