ComammoxNitrospiraare the dominant ammonia oxidizers in a mainstream low dissolved oxygen nitrification reactor

AbstractRecent findings show that a subset of bacteria affiliated withNitrospira, a genus known for its importance in nitrite oxidation for biological nutrient removal applications, are capable ofcompleteammoniaoxidation (comammox) to nitrate. Early reports suggested that they were absent or present in low abundance in most activated sludge processes, and thus likely functionally irrelevant. Here we show the accumulation of comammoxNitrospirain a nitrifying sequencing batch reactor operated at low dissolved oxygen (DO) concentrations. Actual mainstream wastewater was used as influent after primary settling and an upstream pre-treatment process for carbon and phosphorus removal. The ammonia removal rate was stable and exceeded that of the treatment plant’s parallel full-scale high DO nitrifying activated sludge reactor. 16S rRNA sequencing showed a steady accumulation ofNitrospirato 53% total abundance and a decline in conventional ammonia oxidizing bacteria to <1% total abundance over 400+ days of operation. After ruling out other known ammonia oxidizers, qPCR confirmed the accumulation of comammoxNitrospirabeginning around day 200, to eventually comprise 94% of all detectedamoAand 4% of total bacteria by day 407. Quantitative fluorescence in-situ hybridization confirmed the increasing trend and high relative abundance ofNitrospira. These results demonstrate that comammox can be metabolically relevant to nitrogen transformation in wastewater treatment, and can even dominate the ammonia oxidizing community. Our results suggest that comammox may be an important functional group in energy efficient nitrification systems designed to operate at low DO levels.

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Improving nitrogen removal in predenitrification-nitrification biofilters

Water Science & Technology ◽

10.2166/wst.2004.0890 ◽

2004 ◽

Vol 48 (11-12) ◽

pp. 419-428 ◽

Cited By ~ 1

Author(s):

L. Larrea ◽

A. Abad ◽

J. Gayarre

Keyword(s):

Dissolved Oxygen ◽

Activated Sludge ◽

Nitrogen Removal ◽

Suspended Solids ◽

Complete Removal ◽

Cod Removal ◽

Nitrification Rate ◽

Removal Rates ◽

N Removal ◽

Activated Sludge Processes

The effect on NH4-N removal rates in nitrification biofilters of filtered biodegradable COD and particulate COD leaving predenitrification biofilters was studied in a lab scale plant configured with the separated system of biofilters for secondary nitrogen removal from urban wastewaters. Applying a typical COD load of 11 kg/m3.day to the predenitrification biofilter and maximizing its COD removal by adding nitrates or by operating an improved control of the internal recycle, only 60% removal of filtered biodegradable COD was found. This value corresponds to the complete removal of the readily biodegradable substrate (30% of influent filtered COD) and 36% of filtered slowly biodegradable substrate (50% of influent COD). The remaining 64% of the latter entered the nitrification biofilter, causing competition between heterotrophs and nitrifiers for dissolved oxygen in the inner layers of the biofilm. Consequently the nitrification rate had relatively low values (0.5 kgN/m3.d) at 14°C despite using dissolved oxygen levels of 6 mg/l. This behaviour may explain the lower nitrification rates obtained in some cases of nitrification biofilters compared to those in tertiary nitrification after activated sludge processes. The particulate COD entering the nitrification biofilter is associated with the suspended solids leaving the denitrification biofilter which are adsorbed by the external layers of the biofilm, increasing its thickness. The activity of the nitrifiers was affected because of a lack of oxygen when the thickness was left to grow considerably. Therefore no significant particulate COD effect is expected to occur as long as backwashing is carried out with the appropriate frequency.

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Dissolved Oxygen Control for Activated Sludge Processes

IFAC Proceedings Volumes ◽

10.1016/s1474-6670(17)40870-6 ◽

2001 ◽

Vol 34 (8) ◽

pp. 539-544 ◽

Cited By ~ 4

Author(s):

M.A. Brdys ◽

K. Konarczak

Keyword(s):

Dissolved Oxygen ◽

Activated Sludge ◽

Oxygen Control ◽

Dissolved Oxygen Control ◽

Activated Sludge Processes

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MODELING DISSOLVED OXYGEN CONCENTRATION FOR OPTIMIZING AERATION SYSTEMS AND REDUCING OXYGEN CONSUMPTION IN ACTIVATED SLUDGE PROCESSES: A REVIEW

Chemical Engineering Communications ◽

10.1080/00986445.2014.883974 ◽

2014 ◽

Vol 201 (8) ◽

pp. 983-1002 ◽

Cited By ~ 24

Author(s):

Erika Pittoors ◽

Yaping Guo ◽

Stijn W. H. Van Hulle

Keyword(s):

Oxygen Consumption ◽

Dissolved Oxygen ◽

Activated Sludge ◽

Oxygen Concentration ◽

Dissolved Oxygen Concentration ◽

Activated Sludge Processes

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Hierarchical dissolved oxygen control for activated sludge processes

Control Engineering Practice ◽

10.1016/j.conengprac.2007.04.005 ◽

2008 ◽

Vol 16 (1) ◽

pp. 114-131 ◽

Cited By ~ 62

Author(s):

R. Piotrowski ◽

M.A. Brdys ◽

K. Konarczak ◽

K. Duzinkiewicz ◽

W. Chotkowski

Keyword(s):

Dissolved Oxygen ◽

Activated Sludge ◽

Oxygen Control ◽

Dissolved Oxygen Control ◽

Activated Sludge Processes

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Combining fluorescent in situ hybridization (fish) with cultivation and mathematical modeling to study population structure and function of ammonia-oxidizing bacteria in activated sludge

Water Science & Technology ◽

10.2166/wst.1998.0689 ◽

1998 ◽

Vol 37 (4-5) ◽

pp. 441-449 ◽

Cited By ~ 17

Author(s):

Michael Wagner ◽

Daniel R. Noguera ◽

Stefan Juretschko ◽

Gabriele Rath ◽

Hans-Peter Koops ◽

...

Keyword(s):

Mathematical Modeling ◽

In Situ Hybridization ◽

Activated Sludge ◽

Heterotrophic Bacteria ◽

Sewage Treatment Plant ◽

Laser Scanning Microscopy ◽

Industrial Plant ◽

Ammonia Oxidizing Bacteria ◽

Ammonia Oxidizers

16S rRNA-targeted oligonucleotide probes for phylogenetically defined groups of autotrophic ammonia-oxidizing bacteria were used for analyzing the natural diversity of nitrifiers in an industrial sewage treatment plant receiving sewage with high ammonia concentrations. In this facility discontinuous aeration is used to allow for complete nitrification and denitrification. In situ hybridization revealed a yet undescribed diversity of ammonia oxidizers occurring in the plant. Surprisingly, the majority of the ammonia oxidizers were detected with probe combinations which indicate a close affiliation of these cells with Nitrosococcus mobilis. In addition, low numbers of ammonia-oxidizers related to the Nitrosomonas europaea - Nitrosomonas eutropha cluster were present. Interestingly, we also observed hybridization patterns which suggested the occurrence of a novel population of ammonia oxidizers. Confocal laser scanning microscopy revealed that all specifically stained ammonia oxidizers were clustered in microcolonies formed by rod-shaped bacteria. Combination of FISH and mathematical modeling was used to investigate diffusion limitation of ammonia and O2 within these aggregates. Model simulations suggest that mass transfer limitations inside the clusters are not as significant as the substrate limitations due to the activity of surrounding heterotrophic bacteria. To learn more about the ammonia-oxidizers of the industrial plant, we enriched and isolated ammonia-oxidizing bacteria from the activated sludge by combining classical cultivation techniques and FISH. Monitoring the isolates with the nested probe set allowed us to specifically identify those ammonia oxidizers which were found in situ to be numerically dominant. The phylogenetic relationship of these isolates determined by comparative 16S rDNA sequence analysis confirmed the affiliation suggested by FISH.

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Grey-Box Identification of Dissolved Oxygen Dynamics in Activated Sludge Processes

IFAC Proceedings Volumes ◽

10.1016/s1474-6670(17)58776-5 ◽

1996 ◽

Vol 29 (1) ◽

pp. 6804-6809 ◽

Cited By ~ 3

Author(s):

L.J.S. Lukasse ◽

K.J. Keesman ◽

G. van Straten

Keyword(s):

Dissolved Oxygen ◽

Activated Sludge ◽

Activated Sludge Processes ◽

Oxygen Dynamics

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Rapid start-up of a nitrifying reactor using aerobic granular sludge as seed sludge

Water Science & Technology ◽

10.2166/wst.2012.888 ◽

2012 ◽

Vol 65 (3) ◽

pp. 581-588 ◽

Cited By ~ 8

Author(s):

Naohiro Kishida ◽

Goro Saeki ◽

Satoshi Tsuneda ◽

Ryuichi Sudo

Keyword(s):

Removal Rate ◽

Granular Sludge ◽

Ammonia Removal ◽

High Rate ◽

Aerobic Granular Sludge ◽

Nitrite Accumulation ◽

Ammonia Oxidizing Bacteria ◽

Continuous Stirred Tank Reactor ◽

Start Up ◽

Seed Sludge

In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.0 kg N/m3/d within 20 days and up to 1.8 kg N/m3/d on day 39. Subsequently, high rate nitritation was stably attained during 100 days. However, nitrite accumulation had been observed for 140 days before attaining complete nitrification to nitrate. Fluorescence in situ hybridization analysis revealed the increase in amount of ammonia-oxidizing bacteria which existed in the outer edge of the granular sludge during the start-up period. This microbial ecological change would make it possible to attain high rate ammonia removal.

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Influence of dissolved oxygen concentration on the start-up of the anammox-based process: ELAN®

Water Science & Technology ◽

10.2166/wst.2015.233 ◽

2015 ◽

Vol 72 (4) ◽

pp. 520-527 ◽

Cited By ~ 22

Author(s):

N. Morales ◽

A. Val del Río ◽

J. R. Vázquez-Padín ◽

R. Gutiérrez ◽

R. Fernández-González ◽

...

Keyword(s):

Dissolved Oxygen ◽

Removal Rate ◽

Batch Reactor ◽

Thick Layer ◽

Average Diameter ◽

Bulk Liquid ◽

Anammox Bacteria ◽

Total Biomass ◽

Ammonia Oxidizing Bacteria ◽

Anaerobic Digester Supernatant

The anammox-based process ELAN® was started-up in two different sequencing batch reactor (SBR) pilot plant reactors treating municipal anaerobic digester supernatant. The main difference in the operation of both reactors was the dissolved oxygen (DO) concentration in the bulk liquid. SBR-1 was started at a DO value of 0.4 mg O2/L whereas SBR-2 was started at DO values of 3.0 mg O2/L. Despite both reactors working at a nitrogen removal rate of around 0.6 g N/(L d), in SBR-1, granules represented only a small fraction of the total biomass and reached a diameter of 1.1 mm after 7 months of operation, while in SBR-2 the biomass was mainly composed of granules with an average diameter of 3.2 mm after the same operational period. Oxygen microelectrode profiling revealed that granules from SBR-2 where only fully penetrated by oxygen with DO concentrations of 8 mg O2/L while granules from SBR-1 were already oxygen penetrated at DO concentrations of 1 mg O2/L. In this way granules from SBR-2 performed better due to the thick layer of ammonia oxidizing bacteria, which accounted for up to 20% of all the microbial populations, which protected the anammox bacteria from non-suitable liquid media conditions.

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