Preliminary evaluation of the use of fatty acid ratios for tracking the potential for nitrite accumulation in nitrifying reactors with low carbon to nitrogen ratio

Simm, R A; Ramey, William D.; Mavinic, Donald S.

doi:10.1139/s03-053

Cited by 4 publications

(6 citation statements)

References 20 publications

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“…These populations were studied using a combination of slot blot hybridization and fatty acid analyses (Simm et al 2003). These populations were studied using a combination of slot blot hybridization and fatty acid analyses (Simm et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Nitrifier population dynamics in a bench-scale conventional activated sludge reactor following an induced perturbation

Simm¹,

Ramey²,

Mavinic³

2005

Journal of Environmental Engineering and Science

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An instantaneous increase in reactor free ammonia concentration resulted in a gradual decrease in nitrite oxidizer activity that was coincidental with an increase in the nitrous oxide emissions from the reactor. Microbial community analysis using RNA slot blotting techniques indicated that Nitrospira, and not Nitrobacter, populations appeared to be most affected by this induced perturbation. It is hypothesized that competition for nitrite and possibly oxygen between ammonia oxidizers and Nitrospira, and not free ammonia stress, was the true cause of impaired nitrite oxidizer activity.

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Section: Introductionmentioning

confidence: 99%

Nitrifier population dynamics in a bench-scale conventional activated sludge reactor following an induced perturbation

Simm¹,

Ramey²,

Mavinic³

2005

Journal of Environmental Engineering and Science

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“…The analysis procedure was previously described in Simm et al (2004a). The molecular probes used for this assessment included Nso 190 (5'-CGA TCC CCT GCT TTT TCT CC-3') targeting all characterized ammonia-oxidizers in the β subdivision of the Proteobacteria (purple bacteria), Nb 1000 (5'-TGC GAC CGG TCA TGG-3') targeting Nitrobacter, Ntspa-454 (5'-TCC ATC TTC CCT CCC GAA AA -3') targeting Nitrospira moscoviensis and related Nitrospira-like organisms, and Ntspa-685 (5'-CAC CGG GAA TTC CGC GCT CCT C-3') targeting Nitrospira moscoviensis and Nitrospira marina.…”

Section: Rna Slot Blottingmentioning

confidence: 99%

“…Mixed microbial populations were studied using a combination of slot blot hybridization and fatty acid analyses. The potential utility of the fatty acid technique for tracking nitrifier populations was established in a previous study (Simm et al 2004a). …”

Section: Introductionmentioning

confidence: 99%

Mechanisms Responsible for Apparent Free Ammonia Inhibition in a Sequencing Batch Reactor

Simm¹,

Mavinic²,

Ramey³

2007

proc water environ fed

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The primary objective of this study was to track reactor gas emissions and microbial population dynamics during the acclimation of a bench scale SBR system operating via the nitrate shunt, defined here as the oxidation of ammonia to nitrite with denitrification of nitrite to nitrogenous gases, to elucidate potential strategies for overcoming the acclimation response. Aerobic phase nitrite accumulation was induced by periodically subjecting the nitrite oxidizer population to an expected inhibitory concentration of free ammonia under anoxic conditions as previously described by Turk and Mavinic (1986, 1987, 1989a, 1989b.A lab scale sequencing batch reactor (SBR) was operated with a pre-anoxic fill and high pH to subject nitrifiers to free ammonia concentrations reported to be inhibitory during the start of the aerobic phase. The anoxic period pH (and therefore free ammonia concentration) was controlled by adjusting influent feed pH via a combination of sodium hydroxide and sodium bicarbonate addition. This was the same pH control scheme used by others (Turk and Mavinic (1986, 1987, 1989a, 1989b) who have successfully operated systems via the nitrate shunt. The target anoxic zone free ammonia concentration was 8-to-10 mg NH 3 -N/L. The aeration rate was initially kept constant and the aerobic phase dissolved oxygen level was used as a gauge of nitrifier health. Tracking studies were conducted during several SBR cycles both during the shunt period and following the collapse of the shunt (acclimation), in order to elucidate the differences in process response, over and above nitrite accumulation. Changes in reactor microbial populations were tracked using a combination of slot blot hybridization and fatty acid analyses.The control of anoxic free ammonia concentration through influent pH adjustment resulted in nitrite accumulation followed by eventual process acclimation and complete nitrite oxidation. Nitrite oxidation was initiated at free ammonia concentrations far in excess of the inhibitory range reported by Anthonisen et al. (1976). By the time the shunt had collapsed, nitrite oxidation was initiated at free ammonia concentrations exceeding 9 mg-N/L. The period of nitrite accumulation was coincidental with reactor nitrous oxide emissions.RNA and suspended solids data suggest that the entire nitrifier population was severely compromised when the initial feed pH adjustment was made to increase free ammonia concentration and initiate the nitrate shunt. The drop in RNA binding nitrifier molecular probes (Nso 190, Ntspa 454, Ntspa 685 and Nb 1000 probes) coincided with an increase in effluent suspended solids. A drop in RNA concentration of this magnitude suggests the death and lysis of cells. The drop in total RNA suggested the entire population was compromised; however, the nitrite oxidizer population as measured by the Ntspa 454, Ntspa 685 and Nb 1000 RNA probe concentrations was most affected. The establishment of a new suspended solids equilibrium in 820 the reactor supports the possibility that the change in pH ...

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“…The Garrett configuration, in which biomass is wasted directly from the reactor (Grady et al 1999), was used for solids control; solids wasting was carried out daily. The reactor setup has been presented in previous publication (Simm et al 2004a). Two separate mixed culture experiments are reported on here.…”

Section: Mixed Culture Bench Scale Reactor Experimentsmentioning

confidence: 99%

“…The overall performance data for the time period February 1 to March 3, 2002 were presented in a previous publication (referred to as Reactor R5 in Simm et al, 2004a). This reactor was operated at low dissolved oxygen in order to retard nitrification to the point where a free ammonia stress would be maintained (average reactor free ammonia (NH 3 ) concentration ranged between 2.4 to 4.5 mg-N/L) and hydroxylamine could potentially accumulate.…”

Section: Low Dissolved Oxygen Mixed Culture Studymentioning

confidence: 99%

Development of a Conceptual Model to Explain Apparent Free Ammonia Inhibition in Wastewater Systems (WEFTEC 2006)

Simm¹,

Mavinic²,

Ramey³

2006

proc water environ fed

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The common consensus among researchers and practitioners alike is that high free ammonia concentrations cause nitrite oxidizer inhibition in wastewater treatment systems. The work of Anthonisen et al. (1976), who produced an operational chart providing guidance on the free ammonia concentrations most likely to produce nitrite oxidizer inhibition, is considered by many to be the definitive work that established the inhibitory nature of free ammonia in wastewater treatment systems. Over the past three decades several investigators have reported discrepancies in the range of inhibitory free ammonia concentrations. Anthonisen et al. (1976) reported inhibition of nitrite-oxidizers at free ammonia concentrations of 0.1 to 1 mg/L, Turk and Mavinic (1986) reported no significant nitrite-oxidizer inhibition for free ammonia concentrations below 10 mg NH 3 -N/L, whereas Mauret et al. (1996) concluded that free ammonia inhibits Nitrobacter, in the range of 6.6 to 8.9 mg NH 3 -N/L. On the other hand, Gieseke et al. (2003) state that it is not known whether bacteria of the genus Nitrospira, now believed to be the most prevalent nitrite oxidizer in wastewater systems, are inhibited by free ammonia.Some investigators have called into question the true cause of observed nitrite oxidizer inhibition. For example, Cecen and Ipek (1998) suggested that the dissolved oxygen to free ammonia ratio and not the free ammonia concentration itself is important, when attempting to induce nitrite accumulation. The work of others (Stuven et al. 1992;Yang and Alleman 1992;and Hyungseok Yoo et al. 1999) has suggested that hydroxylamine -an intermediate in the ammonia oxidation process -may be the true cause of nitrite oxidizer inhibition and therefore of nitrite accumulation. Many authors agree; however, that selective inhibition of nitrite oxidation via apparent free ammonia inhibition would allow direct oxidation of ammonia to nitrite and denitrification to dinitrogen gas with the inherent benefits of reduced aeration and carbon requirements. The starting point to designing such a process is the development of a clearer understanding of the mechanism(s) associated with nitrite oxidizer inhibition and nitrite accumulation. This paper describes the results of exploratory work conducted to both confirm the results of mixed culture batch tests suggesting free ammonia may not be inhibitory to nitrite oxidizers as commonly reported and elucidate the likely mechanism(s) responsible for observed phenomenon. Free ammonia inhibition trials were undertaken using pure cultures of Nitrospira moscoviensis, since Nitrospira spp. were the predominant nitrite-oxidizers in the systems studied for this research program. The results of these experiments support the conclusion that free ammonia is probably not inhibitory to nitrite-oxidizing organisms in wastewater systems. 6548 WEFTEC®.06Copyright 2006 Water Environment Foundation. All Rights Reserved © Several long-term reactor perturbation studies were conducted with mixed microbial cultures to identi...

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Preliminary evaluation of the use of fatty acid ratios for tracking the potential for nitrite accumulation in nitrifying reactors with low carbon to nitrogen ratio

Cited by 4 publications

References 20 publications

Nitrifier population dynamics in a bench-scale conventional activated sludge reactor following an induced perturbation

Nitrifier population dynamics in a bench-scale conventional activated sludge reactor following an induced perturbation

Mechanisms Responsible for Apparent Free Ammonia Inhibition in a Sequencing Batch Reactor

Development of a Conceptual Model to Explain Apparent Free Ammonia Inhibition in Wastewater Systems (WEFTEC 2006)

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