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Low-dissolved-oxygen nitrification in tropical sewage: An investigation on potential, performance and functional microbial community

Lookup NU author(s): Vincent How, Professor Thomas CurtisORCiD



This is the authors' accepted manuscript of an article that has been published in its final definitive form by IWA Publishing, 2018.

For re-use rights please refer to the publisher's terms and conditions.


© IWA Publishing 2018. Intensive aeration for nitrification is a major energy consumer in sewage treatment plants (STPs). Low-dissolved-oxygen (low-DO) nitrification has the potential to lower the aeration demand. However, the applicability of low-DO nitrification in the tropical climate is not well-understood. In this study, the potential of low-DO nitrification in tropical setting was first examined using batch kinetic experiments. Subsequently, the performance of low-DO nitrification was investigated in a laboratoryscale sequential batch reactor (SBR) for 42 days using real tropical sewage. The batch kinetic experiments showed that the seed sludge has a relatively high oxygen affinity. Thus, the rate of nitrification was not significantly reduced at low DO concentrations (0.5 mg/L). During the operation of the low-DO nitrification SBR, 90% of NH4-N was removed. The active low-DO nitrification was mainly attributed to the limited biodegradable organics in the sewage. Fluorescence in-situ hybridisation and 16S rRNA amplicon sequencing revealed the nitrifiers were related to Nitrospira genus and Nitrosomonadaceae family. Phylogenetic analysis suggests 47% of the operational taxonomic units in Nitrospira genus are closely related to a comammox bacteria. This study has demonstrated active low-DO nitrification in tropical setting, which is a more sustainable process that could significantly reduce the energy footprint of STPs.

Publication metadata

Author(s): How SW, Lim SY, Lim PB, Aris AM, Ngoh GC, Curtis TP, Chua ASM

Publication type: Article

Publication status: Published

Journal: Water Science and Technology

Year: 2018

Volume: 77

Issue: 9

Pages: 2274-2283

Print publication date: 01/05/2018

Online publication date: 28/03/2018

Acceptance date: 15/03/2018

Date deposited: 05/06/2018

ISSN (print): 0273-1223

ISSN (electronic): 1996-9732

Publisher: IWA Publishing


DOI: 10.2166/wst.2018.143


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