The Experts below are selected from a list of 39852 Experts worldwide ranked by ideXlab platform
Andreas Schramm - One of the best experts on this subject based on the ideXlab platform.
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simultaneous p and n removal in a sequencing batch biofilm reactor insights from reactor and microscale investigations
Water Research, 2002Co-Authors: Armin Gieseke, P Arnz, Rudolf Amann, Andreas SchrammAbstract:A sequencing batch biofilm reactor (SBBR) with well established enhanced biological phosphate removal (EBPR) was subjected to higher ammonium concentrations to stimulate and eventually implement simultaneous Nitrification. Changes of activity and populations were investigated by a combination of online monitoring, microsensor measurements and fluorescence in situ hybridisation (FISH) of biofilm sections. Nitrification and nitrifying bacteria were always restricted to the periodically oxic biofilm surface. Both, activity and population size increased significantly with higher ammonium concentrations. Nitrification always showed a delay after the onset of aeration, most likely due to competition for oxygen by coexisting P accumulating and other heterotrophic bacteria during the initial aeration phase. This view is also supported by comparing oxygen penetration and oxygen uptake rates under low and high ammonium conditions. Therefore, simultaneous Nitrification and phosphorus removal in a P removing SBBR appears to be only possible with a sufficiently long oxic period to ensure oxygen availability for nitrifiers.
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simultaneous p and n removal in a sequencing batch biofilm reactor insights from reactor and microscale investigations
Water Research, 2002Co-Authors: Armin Gieseke, P Arnz, Rudolf Ama, Andreas SchrammAbstract:A sequencing batch biofilm reactor (SBBR) with well established enhanced biological phosphate removal (EBPR) was subjected to higher ammonium concentrations to stimulate and eventually implement simultaneous Nitrification. Changes of activity and populations were investigated by a combination of online monitoring, microsensor measurements and fluorescence in situ hybridisation (FISH) of biofilm sections. Nitrification and nitrifying bacteria were always restricted to the periodically oxic biofilm surface. Both, activity and population size increased significantly with higher ammonium concentrations. Nitrification always showed a delay after the onset of aeration, most likely due to competition for oxygen by coexisting P accumulating and other heterotrophic bacteria during the initial aeration phase. This view is also supported by comparing oxygen penetration and oxygen uptake rates under low and high ammonium conditions. Therefore, simultaneous Nitrification and phosphorus removal in a P removing SBBR appears to be only possible with a sufficiently long oxic period to ensure oxygen availability for nitrifiers.
Yongzhe Peng - One of the best experts on this subject based on the ideXlab platform.
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detection of nitrifiers and evaluation of partial Nitrification for wastewater treatment a review
Chemosphere, 2015Co-Authors: Shanyu Wang, Xiong Yang, Shuang Qiu, Yongzhe PengAbstract:Partial Nitrification has gained broad interests in the biological nitrogen removal (BNR) from wastewater, since it alleviates carbon limitation issues and acts as a shortcut nitrogen removal system combined with anaerobic ammonium oxidation (Anammox) process. The occurrence and maintenance of partial Nitrification relies on various conditions, which favor ammonium oxidizing bacteria (AOB) but inhibit or limit nitrite oxidizing bacteria (NOB). The studies of the AOB and NOB activities have been conducted by state-of-the-art molecular techniques, such as Polymerase Chain Reaction (PCR), Quantitative PCR, denaturing gradient gel electrophoresis (DGGE), Fluorescence in situ hybridization (FISH) technique, Terminal Restriction Fragment Length Polymorphism (T-RFLP), Live/Dead BacLight, and quinone profile. Furthermore, control strategies for obtaining partial Nitrification are mainly focused on the pH, temperature, dissolved oxygen concentration, real-time aeration control, sludge retention time, substrate concentration, alternating anoxic and aerobic operation, inhibitor and ultrasonic treatment. Existing problems and further perspectives for the scale-up of partial Nitrification are also proposed and suggested.
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short and long term effects of temperature on partial Nitrification in a sequencing batch reactor treating domestic wastewater
Journal of Hazardous Materials, 2010Co-Authors: Jianhua Guo, Yongzhe Peng, Huiju Huang, Shuying Wang, Jingrong Zhang, Zhongwei WangAbstract:Abstract Partial Nitrification to nitrite has been frequently obtained at high temperatures, but has proved difficult to achieve at low temperatures when treating low strength domestic wastewater. In this study, the long-term effects of temperature on partial Nitrification were investigated by operating a sequencing bath reactor with the use of aeration duration control. The specific ammonia oxidation rate decreased by 1.5 times with the temperature decreasing from 25 to 15 °C. However, low temperature did not deteriorate the stable partial Nitrification performance. Nitrite accumulation ratio was always above 90%, even slightly higher (above 95%) at low temperatures. The nitrifying sludge accumulated with ammonia-oxidizing bacteria (AOB), but washout of nitrite-oxidizing bacteria (NOB) was used to determine the short-term effects of temperature on ammonia oxidation process. The ammonia oxidation rate depended more sensitively on lower temperatures; correspondingly the temperature coefficient θ was 1.172 from 5 to 20 °C, while θ was 1.062 from 20 to 35 °C. Moreover, the larger activation energy (111.5 kJ mol−1) was found at lower temperatures of 5–20 °C, whereas the smaller value (42.0 kJ mol−1) was observed at higher temperatures of 20–35 °C. These findings might be contributed to extend the applicability of the partial Nitrification process in wastewater treatment plants operated under cold weather conditions. It is suggested that the selective enrichment of AOB as well as the washout of NOB be obtained by process control before making the biomass slowly adapt to low temperatures for achieving partial Nitrification to nitrite at low temperatures.
Armin Gieseke - One of the best experts on this subject based on the ideXlab platform.
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simultaneous p and n removal in a sequencing batch biofilm reactor insights from reactor and microscale investigations
Water Research, 2002Co-Authors: Armin Gieseke, P Arnz, Rudolf Amann, Andreas SchrammAbstract:A sequencing batch biofilm reactor (SBBR) with well established enhanced biological phosphate removal (EBPR) was subjected to higher ammonium concentrations to stimulate and eventually implement simultaneous Nitrification. Changes of activity and populations were investigated by a combination of online monitoring, microsensor measurements and fluorescence in situ hybridisation (FISH) of biofilm sections. Nitrification and nitrifying bacteria were always restricted to the periodically oxic biofilm surface. Both, activity and population size increased significantly with higher ammonium concentrations. Nitrification always showed a delay after the onset of aeration, most likely due to competition for oxygen by coexisting P accumulating and other heterotrophic bacteria during the initial aeration phase. This view is also supported by comparing oxygen penetration and oxygen uptake rates under low and high ammonium conditions. Therefore, simultaneous Nitrification and phosphorus removal in a P removing SBBR appears to be only possible with a sufficiently long oxic period to ensure oxygen availability for nitrifiers.
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simultaneous p and n removal in a sequencing batch biofilm reactor insights from reactor and microscale investigations
Water Research, 2002Co-Authors: Armin Gieseke, P Arnz, Rudolf Ama, Andreas SchrammAbstract:A sequencing batch biofilm reactor (SBBR) with well established enhanced biological phosphate removal (EBPR) was subjected to higher ammonium concentrations to stimulate and eventually implement simultaneous Nitrification. Changes of activity and populations were investigated by a combination of online monitoring, microsensor measurements and fluorescence in situ hybridisation (FISH) of biofilm sections. Nitrification and nitrifying bacteria were always restricted to the periodically oxic biofilm surface. Both, activity and population size increased significantly with higher ammonium concentrations. Nitrification always showed a delay after the onset of aeration, most likely due to competition for oxygen by coexisting P accumulating and other heterotrophic bacteria during the initial aeration phase. This view is also supported by comparing oxygen penetration and oxygen uptake rates under low and high ammonium conditions. Therefore, simultaneous Nitrification and phosphorus removal in a P removing SBBR appears to be only possible with a sufficiently long oxic period to ensure oxygen availability for nitrifiers.
Guangxi Xing - One of the best experts on this subject based on the ideXlab platform.
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the effects of rice straw biochar addition on Nitrification activity and nitrous oxide emissions in two oxisols
Soil & Tillage Research, 2016Co-Authors: Lili He, Shenqiang Wang, Xu Zhao, Guangxi XingAbstract:Nitrification rates in Oxisols vary with soil pH and substrate availability. Biochar can be used to improve acid soils. The aim of this study was therefore to investigate the interactive impacts of 1% and 5% (w/w) rice-straw biochar application on Nitrification, ammonia oxidizer populations and nitrous oxide (N2O) emissions over short periods of microcosm incubation in two agricultural Oxisols derived from granite (RGU) and tertiary red sandstone (RTU), respectively. We measured soil nitrate (NO3−) and ammonium (NH4+) concentrations during the incubation and used Nitrification kinetic model to assess the response of Nitrification to biochar addition. We also performed real-time quantitative polymerase chain reaction (qPCR) to quantify the copies of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) genes, and collected N2O gas at various intervals during the 56-day incubation. The addition of ammonium sulfate ((NH4)2SO4-N) stimulated Nitrification in both soils. In RGU, biochar treatments altered soil Nitrification patterns to a first-order reaction model; this stimulation was more pronounced with the increase of biochar application rates. In RTU, 1% biochar treatment increased Nitrification rate constants, and 5% biochar treatment altered Nitrification patterns from a zero-order to a first-order reaction model. Treating the two soils with 5% biochar rates significantly increased AOB gene copy numbers up to 7.88- and 14-fold compared with the no biochar controls in RGU and RTU, respectively, while the treatments had little or reduced effect on AOA gene copy numbers. Biochar addition significantly reduced cumulative N2O emissions up to 37.6% in RGU and 46.4% in RTU, respectively. These results underscore the potential of biochar in the restoration of Nitrification and the reduction of greenhouse gas N2O emission in Oxisols.
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comparison of straw biochar mediated changes in Nitrification and ammonia oxidizers in agricultural oxisols and cambosols
Biology and Fertility of Soils, 2016Co-Authors: Lili He, Yucui Bi, Shenqiang Wang, Xu Zhao, Jin Zhao, Guangxi XingAbstract:The responses of Nitrification on intensively managed agricultural soils following long-term biochar (BC) amendment are poorly understood. The Nitrification potential, abundance, and composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in acidic oxisols and alkaline cambosols following a 3-year BC treatment were investigated using 42-day aerobic incubation, quantitative polymerase chain reaction (qPCR), and clone library approach, respectively. Fresh soils were collected from a wheat/millet rotated pot trial in which 0 (control), 2.25, and 22.5 Mg ha−1 rice straw BCs were added for six consecutive crop seasons. The 22.5 Mg ha−1 BC (BC22.5) treatment enhanced Nitrification in oxisols and even altered Nitrification pattern from zero-order to first-order reaction model. AOA and AOB gene copies in the BC22.5 treatment were 9.55 and 22.0 times, respectively, compared with those in the BC0 treatment. The relative abundance of operational taxonomic units (OTUs) in AOA group 1.1a changed due to BC application, and that of OTU-20 was high in group 1.1b-related under the BC22.5 treatment. AOB community composition shifted toward Nitrosospira cluster 3 and 3-related group under the BC22.5 treatment. Basal Nitrification was already high in cambosols, and BC had minimal effect on Nitrification or AOA/AOB abundance. However, the BC22.5 treatment increased the relative abundance of OTU-9 in Nitrosospira cluster 3 group and that of OTU-13 and OTU-16 in Nitrosospira cluster 3-related groups both being AOB. The BC amendment had minimal effect on ammonia oxidizer composition in cambosols but influenced ammonia oxidizer composition and stimulated Nitrification activity in oxisols.
Hallvard Ødegaard - One of the best experts on this subject based on the ideXlab platform.
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performance of a hybrid activated sludge biofilm process for wastewater treatment in a cold climate region influence of operating conditions
Biochemical Engineering Journal, 2013Co-Authors: Daniele Di Trapani, Magnus Christensson, Michele Torregrossa, Gaspare Viviani, Hallvard ØdegaardAbstract:Abstract The main aim of the study was to investigate a hybrid MBBR process, mostly in terms of organic matter removal and Nitrification, when operating with different values of the mixed liquor sludge retention time (SRT), and highlighting the influence of temperature on the process. Based on experience in practice it was hypothesized that Nitrification could be maintained at far lower SRT's than in conventional activated sludge systems and with high organic loading rates applied. A field gathering campaign has been carried out on a hybrid activated sludge/biofilm. The obtained results highlighted that the pilot plant was capable to remove the organic matter at loading rates up to 3.00 kg TCOD m−3 day−1, also showing very high Nitrification activity. Ammonia uptake rate (AUR) batch test showed that biofilm Nitrification activity increased when the mixed liquor SRT decreased. The final suggestion is that it is possible to run a hybrid reactor with low mixed liquor SRT values, as well as low temperatures, still having a high ammonium removal efficiency, since a large fraction of Nitrification activity will take place in the biofilm.
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Nitrification in a moving bed biofilm reactor
Water Research, 1994Co-Authors: Bjorn Rusten, Hallvard ØdegaardAbstract:Abstract A new biofilm reactor, the moving bed reactor, was studied for Nitrification purposes. The study was partly on laboratory-scale with a prepared water, and partly on pilot-scale with primary or secondary effluent as feed water. The experimental results showed that when alkalinity was in excess and there was no organic load, either the ammonium or the oxygen concentration would be limiting for the Nitrification rate. The shift from the ammonium to the oxygen concentration being rate limiting occurred for an oxygen to ammonium concentration ratio of about 3 g O 2 (g NH 4 -N) −1 . The oxygen concentration had a great influence on the Nitrification rate when oxygen was rate limiting. The Nitrification rate was then close to a first-order function of the oxygen concentration, indicating liquid film diffusion to be the important rate limiting mechanism. Nitrification rates were reduced by increased organic loads. When the organic load exceeded 5 g total BOD 7 m 2 d −1 , the Nitrification became insignificant. With a secondary effluent feed, Nitrification rates of 0.7−1.0 g NO x -N (NO 3 -N + NO 2 -N) m −2 d −1 were achieved at oxygen concentrations between 4.5 and 5 g O 2 m −3 . Curves were constructed for Nitrification at different organic loads when the oxygen concentration was rate limiting.
