scholarly journals Nitrogen removal by denitrification and annamox processes in freshwater rivers of high nitrogen loading region of China

2017 ◽  
Vol 19 (4) ◽  
pp. 650-657 ◽  
Keyword(s):  
River System ◽  
Nitrogen Loading ◽  
Ammonium Oxidation ◽  
Total N ◽  
Membrane Inlet Mass Spectrometry ◽  
Relative Contribution ◽  
N Removal ◽  
The Mean ◽  
High Nitrogen Loading

The importance of anaerobic ammonium oxidation (anammox) – a metabolic pathway that can generate dinitrogen – remains poorly understood in freshwater river system. Using the 15N-isotope pairing technique (15N IPT) combined with membrane inlet mass spectrometry (MIMS), the potential rates of denitrification, anammox and total N removal, and their respective contributions to total N2 production were evaluated in 11 rivers in the Taihu Lake region of China. The measured potential rates of denitrification, total N removal and anammox varied from 18.9±0.3 to 70.0±11.4, 26.3±0.4 to 71.3±11.1 and 1.3±0.3 to 11.0±2.5 μmol N m-2 h-1, respectively. The relative contribution of anammox to total N2 production (ra%) ranged from 2.0±0.8% to 29.9±0.7%. The mean potential denitrification and the total N removal rates varied spatially in these 11 rivers, with the highest rates occurring in the western rivers of the region, while the mean potential anammox rates and ra% displayed the opposite trend with the highest values occurring in the southern rivers of the region. The contents of nitrate and dissolved organic carbon in sediments appeared to be the primary controlling factors for denitrification and anammox in these studied rivers. Our results indicated that the potential rates of N removal varied spatially, and denitrification is the dominant activity for removing fixed N but the role of anammox is not negligible in freshwater rivers.

Simultaneous autotrophic denitrification and nitrification in a low-oxygen reaction environment

2014 ◽  
Vol 70 (4) ◽  
pp. 729-735 ◽  
Author(s):  
Ganapathy Ramanathan ◽  
Christopher M. Sales ◽  
Wen K. Shieh
Keyword(s):  
Residence Time ◽  
Oxygen Demand ◽  
Autotrophic Denitrification ◽  
Low Oxygen ◽  
Total N ◽  
N Removal ◽  
Bioreactor System ◽  
The Mean ◽  
The Stability ◽  
Ammonia Oxidising Bacteria

The occurrence of autotrophic denitrification and nitrification activities by ammonia-oxidising bacteria and nitrite-oxidising bacteria is studied in a bioreactor system operable at low-dissolved oxygen (DO) and at variable oxygen influx rates. At a loading of 3.6 mg NH4+–N/h into the bioreactor, simultaneous autotrophic denitrification and nitrification contributed to NH4+–N removal over oxygen influxes of 2–14 mg O2/h and DO <0.5 mg/L. The maximum autotrophic denitrification (or total-N removal) rates were achieved in a narrow oxygen influx band of 3–5 mg O2/h, where it accounted for up to 36% of NH4+–N removal. At oxygen influx >16 mg O2/h and DO >2 mg/L, autotrophic denitrification ceases and roughly 90% of feed NH4+–N is oxidised to NOX−–N. The stability of total effluent chemical oxygen demand (COD) over the range of oxygen influxes tested confirms the absence of heterotrophic denitrification in the bioreactor. The long solids residence time of the stable biomass zone (21 days) led to production of effluent COD as a result of cell decay, and thus effluent COD was used to calculate more accurately the mean cell residence time.

scholarly journals Autotrophic ammonia removal from landfill leachate using anaerobic membrane bioreactor

2017 ◽  
Author(s):  
S. Suneethi ◽  
Kurian Joseph
Keyword(s):  
Nitrogen Removal ◽  
Landfill Leachate ◽  
Membrane Bioreactor ◽  
Loading Rate ◽  
Ammonia Removal ◽  
Nitrogen Loading ◽  
Ammonium Oxidation ◽  
Anaerobic Membrane Bioreactor ◽  
N Removal ◽  
Anammox Process

Anaerobic Membrane Bioreactor (AnMBR) is an innovative high cell density system having complete biomass retention, high reactor loading and low sludge production and suitable for developing slow growing autotrophic bacterial cultures such as ANAMMOX. The Anaerobic Ammonium Oxidation (ANAMMOX) process is an advanced biological nitrogen removal removes ammonia using nitrite as the electron acceptor without oxygen. The NH4+-N in the landfill leachate that is formed due to the release of nitrogen from municipal solid waste (MSW), when discharged untreated, into the surface water can result in eutrophication, aquatic toxicity and emissions of nitrous oxide (N2O) to atmosphere. Besides, NH4+-N accumulation in landfills poses long term pollution issue with significant interference during post closure thereby requiring its removal prior to ultimate disposal into inland surface waters. The main objective of this study was to investigate the feasibility and treatment efficiency of treating landfill leachate (to check) for removing NH4+-N by adopting ANAMMOX process in AnMBR. The AnMBR was optimized for Nitrogen Loading Rate (NLR) varying from 0.025 to 5 kg NH4+-N/ m3/ d with hydraulic retention time (HRT) ranging from 1 to 3 d. NH4+-N removal efficacy of 85.13 ± 9.67% with the mean nitrogen removal rate (NRR) of 5.54 ± 0.63 kg NH4+-N/ m3/ d was achieved with nitrogen loading rate (NLR) of 6.51 ± 0.20 kg NH4+- N/ m3/ d at 1.5 d HRT. The nitrogen transformation intermediates in the form of hydrazine (N2H4) and hydroxylamine (NH2OH) were 0.008 ± 0.005 mg/L and 0.006 ± 0.001 mg/L, respectively, indicating co-existence of aerobic ammonia oxidizers (AOB) and ANAMMOX. The free ammonia (NH3) and free nitrous acid (HNO2) concentrations were 26.61 ± 16.54 mg/L and (1.66 ± 0.95) x 10-5 mg/L, preventing NO2--N oxidation to NO3--N enabling sustained NH4+- N removal.

Development and optimisation of VFA driven DEAMOX process for treatment of strong nitrogenous anaerobic effluents

2008 ◽  
Vol 57 (3) ◽  
pp. 323-328 ◽  
Author(s):  
S. V. Kalyuzhnyi ◽  
M. A. Gladchenko ◽  
Ho Kang ◽  
A. Mulder ◽  
A. Versprille
Keyword(s):  
Total Nitrogen ◽  
Electron Donor ◽  
Volatile Fatty Acids ◽  
Stable Process ◽  
Ammonia Removal ◽  
Nitrogen Loading ◽  
Ammonium Oxidation ◽  
Total N ◽  
Reject Water ◽  
Total Nitrogen Removal

The recently proposed DEAMOX (DEnitrifying AMmonium OXidation) process combines the anammox reaction with autotrophic denitrifying conditions using sulphide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. This paper firstly presents a feasibility study of the DEAMOX process using synthetic (ammonia + nitrate) wastewater where sulphide is replaced by volatile fatty acids (VFA) as a more widespread electron donor for partial denitrification. Under the influent N-NH4+/N-NO3− and COD/N-NO3− ratios of 1 and 2.3, respectively, the typical efficiencies of ammonia removal were around 40% (no matter whether a VFA mixture or only acetate were used) for nitrogen loading rates (NLR) up to 1236 mg N/l/d. This parameter increased to 80% by increasing the influent COD/N-NO3− ratio to 3.48 and decreasing the influent N-NH4+/N-NO3− ratio to 0.29. As a result, the total nitrogen removal increased to 95%. The proposed process was further tested with typical strong nitrogenous effluent such as reject water (total N, 530–566 mg N/l; total COD, 1530–1780 mg/l) after thermophilic sludge anaerobic digestion. For this, the raw wastewater was split and partially (∼50%) fed to a nitrifying reactor (to generate nitrate) and the remaining part (∼50%) was directed to the DEAMOX reactor where this stream was mixed with the nitrified effluent. Stable process performance up to NLR of 1,243 mg N/l/d in the DEAMOX reactor was achieved resulting in 40, 100, and 66% removal of ammonia, NOx−, and total nitrogen, respectively.

Nitrogen Removal by River Systems of the Feng River Basin in China

2014 ◽  
Vol 1015 ◽  
pp. 631-634
Author(s):  
Jian Hui Zhi ◽  
Ai Zhong Ding ◽  
Shu Rong Zhang
Keyword(s):  
Water System ◽  
River System ◽  
Dry Season ◽  
River Network ◽  
Nitrogen Loading ◽  
Combined Processes ◽  
River Systems ◽  
N Removal ◽  
N Input ◽  
The Impact

As human activities continue to alter the global nitrogen cycle, the ability to predict the impact of increased nitrogen loading to river systems is becoming more and more important. Nitrogen retention is of particular interest because it is through its combined processes that local and downstream nitrogen concentrations are reduced. To determine the potential for N removed from Feng River network, we used stream chemistry and hydrogeo-morphology data from 17 stream and river sites to estimate NO3-–N removal in Feng River system of China. We used a N removal model to predict NO3-–N input and removal in December of 2011. NO3-–N input ranged from 0.06 to 20 kg km-1d-1in the Feng River system. Cumulative river network NO3-–N input was 446 ton year-1 in dry season in whole water system. NO3–N removal based on the model ranged from 0.04 to 4.2 kg km-1d-1 December of 2011 for Feng River. Cumulative river network NO3-–N removal predicted by the model was 58 ton year-1 in dry season. Proportional NO3–N removal (PNR) ranged from 0.2 to 0.6 in this time. PNR was negatively correlated with both stream orders.

Use of nitrogen stable isotope ratio of periphyton for monitoring nitrogen sources in a river system

2002 ◽  
Vol 46 (11-12) ◽  
pp. 431-435 ◽  
Author(s):  
H. Toda ◽  
Y. Uemura ◽  
T. Okino ◽  
T. Kawanishi ◽  
H. Kawashima
Keyword(s):  
Stable Isotope ◽  
Isotope Ratio ◽  
Nitrogen Sources ◽  
River System ◽  
Stable Isotope Ratio ◽  
Nitrogen Loading ◽  
Livestock Waste ◽  
Total N ◽  
N Sources ◽  
N Loading

In order to confirm the usefulness of the N stable isotope ratio of periphyton (mainly composed of attached algae) as an indicator for monitoring the N sources in river watersheds, we measured the isotope ratio of periphyton along the Chikuma River. In the river, both the concentrations of dissolved total nitrogen (DTN) and the δ15N values of periphyton increased downstream. Specific nitrogen loading rates (SNLR) calculated from administrative data also showed an increase downstream from 7 to 11 kg N ha−1 yr−1, with the increasing contribution by sewage and livestock waste from 6 to 40% to total N loading. There are significant positive relationships between the DTN concentration and the SNLR (r2 = 0.54, P<0.05), and the δ15N values of periphyton and the SNLR (r2 = 0.78, P<0.05). The increase in DTN concentration reflected the increase in input of N loading. The increase in δ15N of periphyton might reflect the increase in relative contribution by sewage and livestock waste down the river, especially the increase in sewage. The present study indicates the usefulness of the N stable isotope ratio of periphyton as an indicator for monitoring N sources in a river system.

scholarly journals Effects of Ca2+ Concentration on Anaerobic Ammonium Oxidation Reactor Microbial Community Structure

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1341 ◽  
Author(s):  
Ma ◽  
Jin ◽  
Zhang
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Anaerobic Ammonium Oxidation ◽  
Microbiological Analysis ◽  
Ammonium Oxidation ◽  
Total N ◽  
Treatment Performance ◽  
N Removal ◽  
Oxidation Reactor

The anaerobic ammonium oxidation (anammox) reaction removes nitrogen from wastewater, the performance of which is influenced by Ca2+; however, the effect of Ca2+ on microbial community structure is unclear. Therefore, the effects of Ca2+ concentration on the treatment performance of an anammox reactor and microbial community structure of anammox sludge were investigated. Ca2+ concentration minimally influenced the removal efficiency of NO2−–N and NH4+–N, but substantially influenced total N removal. Changing the Ca2+ concentration (between 25 and 125 mg/L) caused the average removal rate of total nitrogen to fluctuate by 3.3 percentage points. There were five major bacterial phyla in the anammox sludge: Proteobacteria, Chloroflexi, Acidobacteria, Planctomycete, and Chlorobi. Microbiological analysis revealed that the genera Acidobacterium, Anaerolinea, and Denitratisoma were positively correlated with Ca2+ concentration, and improved treatment performance of the anammox reactor. Moreover, uncultured Chlorobi bacterium clone RUGL1-218 (GQ421108.1) and uncultured sludge bacterium A21b (KT182572.1) may be key microorganisms for the immobilization of anammox bacteria. These findings offer a theoretical basis for improved wastewater treatment using the anammox process.

scholarly journals Oxygen and light determine the pathways of nitrate reduction in a highly saline lake

2020 ◽  
Author(s):  
Nicolás Valiente ◽  
Franz Jirsa ◽  
Thomas Hein ◽  
Wolfgang Wanek ◽  
Patricia Bonin ◽  
...  
Keyword(s):  
Nitrate Reduction ◽  
Environmental Gradients ◽  
Nitrate Removal ◽  
Hypersaline Lake ◽  
N2o Emissions ◽  
Ammonium Oxidation ◽  
Lake Ecosystems ◽  
N Removal ◽  
Mesocosm Experiments

Abstract. Nitrate (NO3−) removal from aquatic ecosystems involves several microbially mediated processes including denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and anaerobic ammonium oxidation (anammox) regulated by slight changes in environmental gradients. Saline lakes are prone to the accumulation of anthropogenic contaminants, making them highly vulnerable environments to NO3− pollution. We investigated nitrate removal pathways in mesocosm experiments using lacustrine, undisturbed, organic-rich sediments from Pétrola Lake (Spain), a highly saline waterbody subject to anthropogenic NO3− pollution. We used the revised 15N-isotope pairing technique (15N-IPT) to determine NO3− sink processes. Our results demonstrate the coexistence of denitrification, DNRA, and anammox processes, and their contribution was determined by environmental conditions (oxygen and light). DNRA and N2O-denitrification were the dominant nitrogen (N) removal pathways when oxygen and/or light were present (up to 82 %). In contrast, anoxia and darkness promoted NO3− reduction by DNRA (52 %) and N loss by anammox (28 %). Our results highlight the role of coupled DNRA-anammox, as yet has never been investigated in hypersaline lake ecosystems. We conclude that anoxia and darkness favored DNRA and anammox processes over denitrification and therefore reduce N2O emissions to the atmosphere.

scholarly journals Production of N2 through Anaerobic Ammonium Oxidation Coupled to Nitrate Reduction in Marine Sediments

2002 ◽  
Vol 68 (3) ◽  
pp. 1312-1318 ◽  
Author(s):  
Bo Thamdrup ◽  
Tage Dalsgaard
Keyword(s):  
Marine Sediments ◽  
Nitrogen Cycle ◽  
Nitrate Reduction ◽  
Anaerobic Ammonium Oxidation ◽  
Ammonium Oxidation ◽  
Fixed Nitrogen ◽  
Total N ◽  
Nitrogen Budgets ◽  
Relative Contribution ◽  
Anoxic Waters

ABSTRACT In the global nitrogen cycle, bacterial denitrification is recognized as the only quantitatively important process that converts fixed nitrogen to atmospheric nitrogen gas, N2, thereby influencing many aspects of ecosystem function and global biogeochemistry. However, we have found that a process novel to the marine nitrogen cycle, anaerobic oxidation of ammonium coupled to nitrate reduction, contributes substantially to N2 production in marine sediments. Incubations with 15N-labeled nitrate or ammonium demonstrated that during this process, N2 is formed through one-to-one pairing of nitrogen from nitrate and ammonium, which clearly separates the process from denitrification. Nitrite, which accumulated transiently, was likely the oxidant for ammonium, and the process is thus similar to the anammox process known from wastewater bioreactors. Anaerobic ammonium oxidation accounted for 24 and 67% of the total N2 production at two typical continental shelf sites, whereas it was detectable but insignificant relative to denitrification in a eutrophic coastal bay. However, rates of anaerobic ammonium oxidation were higher in the coastal sediment than at the deepest site and the variability in the relative contribution to N2 production between sites was related to large differences in rates of denitrification. Thus, the relative importance of anaerobic ammonium oxidation and denitrification in N2 production appears to be regulated by the availability of their reduced substrates. By shunting nitrogen directly from ammonium to N2, anaerobic ammonium oxidation promotes the removal of fixed nitrogen in the oceans. The process can explain ammonium deficiencies in anoxic waters and sediments, and it may contribute significantly to oceanic nitrogen budgets.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Supernatural norm enforcement: Thinking about Karma and God reduces selfishness among believers

2018 ◽  
Author(s):  
Cindel White ◽  
John Michael Kelly ◽  
Azim Shariff ◽  
Ara Norenzayan
Keyword(s):  
Social Norms ◽  
Framing Effects ◽  
Demographic Variables ◽  
Exclusion Criteria ◽  
Total N ◽  
Norm Enforcement ◽  
Dictator Games ◽  
Within Subjects

Four experiments (total N = 3591) examined how thinking about Karma and God increases adherence to social norms that prescribe fairness in anonymous dictator games. We found that (1) thinking about Karma decreased selfishness among karmic believers across religious affiliations, including Hindus, Buddhists, Christians, and non-religious Americans; (2) thinking about God also decreased selfishness among believers in God (but not among non-believers), replicating previous findings; and (3) thinking about both karma and God shifted participants’ initially selfish offers towards fairness (the normatively prosocial response), but had no effect on already fair offers. These supernatural framing effects were obtained and replicated in high-powered, pre-registered experiments and remained robust to several methodological checks, including hypothesis guessing, game familiarity, demographic variables, between- and within-subjects designs, and variation in data exclusion criteria. These results support the role of culturally-elaborated beliefs about supernatural justice as a motivator of believer’s adherence to prosocial norms.

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