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Effects of extremely low bulk liquid DO on autotrophic nitrogen removal performance and NOB suppression in side‐ and mainstream one‐stage PNA
Author(s) -
Akaboci Tiago Rogerio Vitor,
Gich Frederic,
Ruscalleda Maël,
Balaguer Maria Dolors,
Colprim Jesús
Publication year - 2018
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5649
Subject(s) - anammox , nitrite , nitrospira , chemistry , autotroph , ammonium , nitrogen , ammonia , sequencing batch reactor , food science , bacteria , environmental engineering , denitrification , nitrate , denitrifying bacteria , biochemistry , sewage treatment , biology , environmental science , organic chemistry , genetics
Abstract BACKGROUND Results in the literature are divergent regarding dissolved oxygen (DO) level to ensure nitrite‐oxidizing bacteria (NOB) suppression in mainstream conditions. In this study, a one‐stage granular partial‐nitritation (PNA) was operated controlling the oxygen transfer over ammonium loading rate (OTR/ALR). The effects of extremely low DO availability on autotrophic nitrogen removal (ANR) performance and NOB suppression were assessed. RESULTS The strategy applied in the sequencing batch reactor (SBR) in sidestream and mainstream conditions (temperature at 25 °C) allowed micromolar bulk liquid DO concentrations to be obtained. Nitrite production rate (NPR) by aerobic ammonium‐oxidizing bacteria (AOB) was sufficient to provide nitrite to anammox bacteria (AnAOB) and sustain nitrogen removal rates (NRR) of 0.34 ± 0.05 and 0.37 ± 0.07 kg N m −3 d −1 during sidestream and mainstream operation, respectively. Extremely low DO assisted by free ammonia (FA; ≤6.2 mg N L −1 ) in sidestream conditions resulted in complete nitratation suppression. In mainstream conditions, Nitrospira spp. growth led to limited nitratation rates. Decreasing the OTR/ALR resulted in lower oxygen consumption by AOB than by NOB, as well as reduced nitrite consumption by AnAOB, which is likely to be due to granule structure. CONCLUSIONS Low DO availability did not compromise ANR. Micromolar DO allowed complete NOB suppression only with FA assistance (sidestream) but was sufficient to keep nitratation limited in mainstream conditions. © 2018 Society of Chemical Industry