High Dissolved Oxygen Selection against Nitrospira Sublineage I in Full-Scale Activated Sludge

Yingyu Law, Artur Matysik, Xueming Chen, Sara Swa Thi, Thi Quynh Ngoc Nguyen, Guanglei Qiu, Gayathri Natarajan, Rohan B H Williams, Bing-Jie Ni, Thomas William Seviour, Stefan Wuertz*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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A single Nitrospira sublineage I OTU was found to perform nitrite oxidation in full-scale domestic wastewater treatment plants (WWTPs) in the tropics. This taxon had an apparent oxygen affinity constant lower than that of the full-scale domestic activated sludge cohabitating ammonium oxidizing bacteria (AOB) (0.09 ± 0.02 g O2 m-3 versus 0.3 ± 0.03 g O2 m-3). Thus, nitrite oxidizing bacteria (NOB) may in fact thrive under conditions of low oxygen supply. Low dissolved oxygen (DO) conditions selected for and high aeration inhibited the NOB in a long-term lab-scale reactor. The relative abundance of Nitrospira sublineage I gradually decreased with increasing DO until it was washed out. Nitritation was sustained even after the DO was lowered subsequently. The morphologies of AOB and NOB microcolonies responded to DO levels in accordance with their oxygen affinities. NOB formed densely packed spherical clusters with a low surface area-to-volume ratio compared to the Nitrosomonas-like AOB clusters, which maintained a porous and nonspherical morphology. In conclusion, the effect of oxygen on AOB/NOB population dynamics depends on which OTU predominates given that oxygen affinities are species-specific, and this should be elucidated when devising operating strategies to achieve mainstream partial nitritation.
Original languageEnglish
JournalEnvironmental Science and Technology
Issue number14
Pages (from-to)8157-8166
Publication statusPublished - 2019

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