High-resolution mapping and modeling of anammox recovery from recurrent oxygen exposure

D Seuntjens; J M Carvajal-Arroyo; M Ruopp; P Bunse; C P De Mulder; S Lochmatter; S Agrawal; N Boon; S Lackner; S E Vlaeminck

doi:10.1016/j.watres.2018.07.024

High-resolution mapping and modeling of anammox recovery from recurrent oxygen exposure

Water Res. 2018 Nov 1:144:522-531. doi: 10.1016/j.watres.2018.07.024. Epub 2018 Jul 11.

Authors

D Seuntjens¹, J M Carvajal-Arroyo¹, M Ruopp², P Bunse², C P De Mulder³, S Lochmatter¹, S Agrawal², N Boon¹, S Lackner², S E Vlaeminck⁴

Affiliations

¹ Center for Microbial Ecology and Technology (CMET), Ghent University, Gent, Belgium.
² Technische Universität Darmstadt, Institute IWAR, Chair of Wastewater Engineering, Darmstadt, Germany.
³ Biomath, Ghent University, Gent, Belgium.
⁴ Center for Microbial Ecology and Technology (CMET), Ghent University, Gent, Belgium; Research Group of Sustainable Energy, Air and Water Technology, University of Antwerp, Antwerpen, Belgium. Electronic address: siegfried.vlaeminck@uantwerpen.be.

PMID: 30077912
DOI: 10.1016/j.watres.2018.07.024

Abstract

Oxygen inhibits anammox, a bioconversion executed by anoxic ammonium oxidizing bacteria (AnAOB). Nonetheless, oxygen is mostly found in the proximity of AnAOB in nitrogen removal applications, being a substrate for nitritation. The experiments performed to date were mostly limited to batch activity tests where AnAOB activity is estimated during oxygen exposure. However, little attention has been paid to the recovery and reversibility of activity following aerobic conditions, of direct relevance for bioreactor operation. In this work, anoxic and autotrophic reactor cultivation at 20 °C yielded an enriched microbial community in AnAOB, consisting for 75% of a member of the genus Brocadia. High-resolution kinetic data were obtained with online ammonium measurements and further processed with a newly developed Python data pipeline. The experimentally obtained AnAOB response showed complete inhibition until micro-aerobic conditions were reached again (<0.02 mg O₂ L^-1). After oxygen inhibition, AnAOB recovered gradually, with recovery times of 5-37 h to reach a steady-state activity, dependent on the perceived inhibition. The recovery immediately after inhibition was lowest when exposed to higher oxygen concentrations (range: 0.5-8 mg O₂ L^-1) with long contact times (range: 9-24 h). The experimental data did not fit well with a conventional 'instant recovery' Monod-type inhibition model. Yet, the fit greatly improved by incorporating a dynamic growth rate formula accurately describing gradual activity recovery. With the upgraded model, long-term kinetic simulations for partial nitritation/anammox (PN/A) with intermittent aeration showed a decrease in growth rate compared to the instant recovery mode. These results indicate that recovery of AnAOB after oxygen exposure was previously overlooked. It is recommended to account for this effect in the intensification of partial nitritation/anammox.

Keywords: Energy-positive; Inhibition; Intermittent aeration; Monod; Partial nitritation/anammox; Sewage treatment.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Ammonium Compounds / metabolism
Autotrophic Processes
Bacteria / metabolism*
Bioreactors / microbiology*
Models, Theoretical*
Nitrogen
Oxygen / metabolism*
Waste Disposal, Fluid / instrumentation
Waste Disposal, Fluid / methods*

Substances

Ammonium Compounds
Nitrogen
Oxygen