Floc-based sequential partial nitritation and anammox at full scale with contrasting <script type="math/tex">N_{2}O</script> emissions

Desloover, Joachim; De Clippeleir, Haydee; Boeckx, Pascal; Du Laing, Gijs; Colsen, Joop; Verstraete, Willy; Vlaeminck, Siegfried E.

doi:10.1016/J.WATRES.2011.02.028

Title

Floc-based sequential partial nitritation and anammox at full scale with contrasting $N_{2}O$ emissions

Author

Desloover, Joachim

De Clippeleir, Haydee

Boeckx, Pascal

Du Laing, Gijs

Colsen, Joop

Verstraete, Willy

Vlaeminck, Siegfried E.

Abstract

New Activated Sludge (NAS (R)) is a hybrid, floc-based nitrogen removal process without carbon addition, based on the control of sludge retention times (SRT) and dissolved oxygen (DO) levels. The aim of this study was to examine the performance of a retrofitted four-stage NAS (R) plant, including on-line measurements of greenhouse gas emissions (N2O and CH4). The plant treated anaerobically digested industrial wastewater, containing 264 mg N L-1, 1154 mg chemical oxygen demand (COD) L-1 and an inorganic carbon alkalinity of 34 meq L-1. The batch-fed partial nitritation step received an overall nitrogen loading rate of 0.18-0.22 kg N m(-3) d(-1), thereby oxidized nitrogen to nitrite (45-47%) and some nitrate (13-15%), but also to N2O (5.1-6.6%). This was achieved at a SRT of 1.7 d and DO around 1.0 mg O-2 L-1. Subsequently, anammox, denitrification and nitrification compartments were followed by a final settler, at an overall SRT of 46 d. None of the latter three reactors emitted N2O. In the anammox step, 0.26 kg N M-3 d(-1) was removed, with an estimated contribution of 71% by the genus Kuenenia, which constituted 3.1% of the biomass. Overall, a nitrogen removal efficiency of 95% was obtained, yielding a dischargeable effluent. Retrofitting floc-based nitrification/denitrification with carbon addition to NAS (R) allowed to save 40% of the operational wastewater treatment costs. Yet, a decrease of the N2O emissions by about 50% is necessary in order to obtain a CO2 neutral footprint. The impact of emitted CH4 was 20 times lower. (C) 2011 Elsevier Ltd. All rights reserved.

Language

English

Source (journal)

Water research / International Association on Water Pollution Research. - Oxford, 1967, currens

Publication

Oxford : 2011

ISSN

0043-1354 [print]

1879-2448 [online]

DOI

10.1016/J.WATRES.2011.02.028

Volume/pages