Distinctive NO and N 2 O emission patterns in ammonia oxidizing bacteria: Effect of ammonia oxidation rate, DO and pH

Abstract

This study aims at investigating the relationship between the nitric oxide (NO) and nitrous oxide (N 2 O) production rates with the ammonia oxidation rate (AORsp) in an enriched AOB culture. Different concentrations of ammonia were applied in a sequential batch reactor (SBR) performing partial nitritation in order to determine the effect of AORsp on N 2 O and NO production rates. Results showed that NO linearly correlates with the AORsp whereas N 2 O presents an exponential relationship. The effect of changes on the dissolved oxygen (DO) concentration on the overall NO and N 2 O emissions was assessed by increasing and decreasing the DO maintaining a constant pH at 7. When DO decreased the AORsp was maintained at the level achieved with the starting DO and led to lower NO and N 2 O emissions than when DO was increased. Finally, the effect of pH on N 2 O and NO was also tested by maintaining the DO at 1.5-2 mg O 2 /L while pH was gradually decreased from 8 to 6.5. Results show that NO was chemically produced due to the addition of HCl when decreasing the pH whereas N 2 O was only produced biologically and was not affected by the addition of HCl.

Nitrous oxide production in intermittently aerated Partial Nitritation-Anammox reactor: oxic N2O production dominates and relates with ammonia removal rate

“…High concentrations of NH 4 + and oxic conditions have been described to promote N 2 O production, when high nitrogen oxidation rates occur [37][38][39]. The linear correlation between the specific N 2 O production rate and the specific AOR observed in this study, matches findings from a AOB enrichment cultures (Fig.3) [40,41]. In the reported AOB enrichment cultures the specific N 2 O production rate correlated linearly with AORs below 100 mg NH 3 -N*gVSS -1 *h -1 .…”

Genome-Scale, Constraint-Based Modeling of Nitrogen Oxide Fluxes during Coculture of Nitrosomonas europaea and Nitrobacter winogradskyi

“…NH 3 oxidation and growth rate data generated in previous studies suggests that an increased NH 3 oxidation rate leads to uncoupling of NH 3 oxidation from growth, forcing N. europaea to direct electrons to NIR and NOR to regenerate reductant (21, 46–48). In addition, the integrative model reported here suggests different energy outcomes for the cell based on abiotic oxidation of NO to NO 2 − .…”

Considering Water Quality of Urban Rivers from the Perspectives of Unpleasant Odor

“…If DO concentration is high, nitrogen compounds are degraded into ammonia and then nitrate during aerobic decomposition [35,36]. If DO concentration below 2 mg L −1 is considered as hypoxic condition [19,20,32], upstream did not face hypoxia after 2000, and downstream periodically faced hypoxic condition after 2000 at both rivers.…”