Oxygen-induced dynamics of nitrous oxide in water and off-gas during the treatment of digester supernatant

2013 ◽  
Vol 69 (1) ◽  
pp. 84-91 ◽  
Author(s):  
F. Stenström ◽  
K. Tjus ◽  
J. la Cour Jansen
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Oxygen Concentration ◽  
Total Nitrogen ◽  
Batch Reactor ◽  
Full Scale ◽  
Bulk Liquid ◽  
N2o Emissions ◽  
Low Oxygen ◽  
Low Oxygen Concentration

Nitrous oxide (N2O) is a potent greenhouse gas and of special concern in wastewater treatment. It is formed in biological wastewater treatment under both aerobic and anaerobic conditions. A major reason for high N2O emissions is low oxygen concentration during nitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentration and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen concentration during nitrification led to increased nitrite concentration, which in turn led to increased N2O concentration in the subsequent denitrification phase. When the nitrification resumed, accumulated N2O was stripped off to the atmosphere. Very high concentrations of N2O, over 56,000 ppmv, were measured in the off-gas. Furthermore, the maximum amount of N2O emitted during one cycle corresponded to 107.6% of the total nitrogen load (21.9% of total nitrogen present in the bulk liquid at the beginning of the cycle). This is among the highest emission levels ever measured from a full-scale municipal plant for digester supernatant.

Mathematical Modeling of Nitrous Oxide (N2O) Emissions from Full-Scale Wastewater Treatment Plants

2013 ◽  
Vol 47 (14) ◽  
pp. 7795-7803 ◽  
Author(s):  
Bing-Jie Ni ◽  
Liu Ye ◽  
Yingyu Law ◽  
Craig Byers ◽  
Zhiguo Yuan
Keyword(s):  
Mathematical Modeling ◽  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Full Scale ◽  
N2o Emissions

Full-scale comparison of N2O emissions from SBR N/DN operation versus one-stage deammonification MBBR treating reject water – and optimization with pH set-point

2019 ◽  
Vol 79 (8) ◽  
pp. 1616-1625 ◽  
Author(s):  
L. Kanders ◽  
J-J. Yang ◽  
C. Baresel ◽  
J. Zambrano
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment Plants ◽  
Feeding Strategy ◽  
Batch Reactor ◽  
Full Scale ◽  
Biofilm Reactor ◽  
N2o Emissions ◽  
Set Point ◽  
Reject Water ◽  
Aeration Time

Abstract To be able to fulfill the Paris agreement regarding anthropogenic greenhouse gases, all potential emissions must be mitigated. Wastewater treatment plants should aim to eliminate emissions of the most potent greenhouse gas, nitrous oxide (N2O). In this study, these emissions were measured at a full-scale reject water treatment tank during two different operation modes: nitrification/denitrification (N/DN) operating as a sequencing batch reactor (SBR), and deammonification (nitritation/anammox) as a moving bed biofilm reactor (MBBR). The treatment process emitted significantly less nitrous oxide in deammonification mode 0.14–0.7%, compared to 10% of total nitrogen in N/DN mode. The decrease can be linked to the changed feeding strategy, the lower concentrations of nitrite, a lower load of ammonia oxidized, a shorter aeration time, the absence of non-optimized ethanol dosage or periodic lack of oxygen as well as the introduction of biofilm. Further, evaluation was done how the operational pH set point influenced the emissions in deammonification mode. Lower concentrations of nitrous oxide were measured in water phase at higher pH (7.5–7.6) than at lower pH (6.6–7.1). This is believed to be mainly because of the lower aeration ratio and increased complete denitrification at the higher pH set point.

Effect of low oxygen concentration on activation of inflammation by Helicobacter pylori

2021 ◽  
Vol 560 ◽  
pp. 179-185
Author(s):  
Adiza Abass ◽  
Tokuju Okano ◽  
Kotchakorn Boonyaleka ◽  
Ryo Kinoshita-Daitoku ◽  
Shoji Yamaoka ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Oxygen Concentration ◽  
Low Oxygen ◽  
Low Oxygen Concentration

The Constant Low Oxygen Concentration in All the Target Cells for Mouse Tail Radionecrosis

1982 ◽  
Vol 92 (1) ◽  
pp. 172 ◽  
Author(s):  
J. H. Hendry ◽  
J. V. Moore ◽  
B. W. Hodgson ◽  
J. P. Keene
Keyword(s):  
Oxygen Concentration ◽  
Target Cells ◽  
Low Oxygen ◽  
Low Oxygen Concentration

scholarly journals Simultaneous Nitrification and Denitrification in an SBR with a Modified Cycle During Reject Water Treatment

2013 ◽  
Vol 39 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Katarzyna Bernat
Keyword(s):  
Batch Reactor ◽  
Anaerobic Sludge ◽  
Simultaneous Nitrification And Denitrification ◽  
Low Oxygen ◽  
Total Removal ◽  
Operational Conditions ◽  
Reject Water ◽  
Do Concentration ◽  
Nitrification And Denitrification ◽  
Low Oxygen Concentration

Abstract In this study, the dependence between volumetric exchange rate (n) in an SBR (Sequencing Batch Reactor) with a modified cycle and simultaneous nitrification and denitrification (SND) efficiency during the treatment of anaerobic sludge digester supernatant was determined. In the SBR cycle alternating three aeration phases (with limited dissolved oxygen (DO) concentration up to 0.7 mg O2/L) and two mixing phases were applied. The lengths of each aeration and mixing phases were 4 and 5.5 h, respectively. Independently of n, a total removal of ammonium was achieved. However, at n = 0.1 d-1 and n = 0.3 d-1 nitrates were the main product of nitrification, while at n = 0.5 d-1, both nitrates and nitrites occurred in the effluent. Under these operational conditions, despite low COD/N (ca. 4) ratio in the influent, denitrification in activated sludge was observed. A higher denitrification efficiency at n = 0.5 d-1 (51.3%) than at n = 0.1 d-1 (7.8%) indicated that n was a crucial factor influencing SND via nitrite and nitrate in the SBR with a low oxygen concentration in aeration phases.

scholarly journals Zooplankton fluctuations in Jurumirim Reservoir (São Paulo, Brazil): a three-year study

2009 ◽  
Vol 69 (1) ◽  
pp. 1-18 ◽  
Author(s):  
LP. Sartori ◽  
MG. Nogueira ◽  
R. Henry ◽  
EM. Moretto
Keyword(s):  
Water Column ◽  
Oxygen Concentration ◽  
Retention Time ◽  
Sao Paulo ◽  
Seasonal Effect ◽  
São Paulo ◽  
Low Oxygen ◽  
High Concentration ◽  
Heterogeneous Distribution ◽  
Low Oxygen Concentration

During three consecutive years, monthly samples of zooplankton were taken in the lacustrine (dam) zone of Jurumirim (São Paulo, Brazil). The seasonal effect on basic limnological features (thermal regime, oxygen distribution, phytoplankton biomass, etc.) was also examined. The influence of the seasonality on the fluctuation of the zooplankton composition and abundance was not clearly detected (low degree of recurrent patterns). Rotifers (32 taxa) were the most abundant organisms during almost the entire study period with some seasonal alternations in the maximum abundance peaks of the main taxa (Conochilus unicornis, Keratella americana, K. cochlearis and Hexarthra spp.), except for Polyarthra (mainly P. vulgaris). Only occasionally copepods were numerically dominant. Higher copepod abundance was positively associated to periods of increase in the water retention time. Among the Copepoda (10 taxa) the calanoids (mainly Notodiaptomus iheringi) were more abundant, especially in warmer periods. Conversely, cyclopoids had higher abundance in autumn and winter. The species Thermocyclops minutus and T. decipiens co-occurred, but the first attained higher abundance. Some evidence of co-existence strategies between both species are considered. Cladocera (17 taxa) was never numerically dominant and the main taxa (Bosmina spp., Ceriodaphnia spp. and Diaphanosoma spp.) occurred almost the whole study period and did not present a seasonal pattern of fluctuation. Diaphanosoma (mainly D. birgei) attained the highest abundance among cladocerans. Most organisms were always found at the surface, but they also occupy the whole water column, even in periods of stratified conditions and low oxygen concentration in the bottom layers. Among the main zooplanktonic taxa, only Hexarthra avoids deep layers. An exceptionally high concentration of Copepoda nauplii on the surface was influenced by low transparency, high concentration of phytoplankton at this layer and low oxygen concentration at the bottom. In periods of higher retention timevariability there was a more heterogeneous distribution of the zooplankton in the water column. The increase in the retention time seems also to favor the copepod development. Finally, some inter-decade changes are considered on the basis of zooplankton assemblage structure observations.

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