Articoli di riviste: "Nitrifying"

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Ayiti, Oluwatobi Esther, Ayansina Segun Ayangbenro e Olubukola Oluranti Babalola. "16S Amplicon Sequencing of Nitrifying Bacteria and Archaea Inhabiting Maize Rhizosphere and the Influencing Environmental Factors". Agriculture 12, n. 9 (28 agosto 2022): 1328. http://dx.doi.org/10.3390/agriculture12091328.

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Nitrifying bacteria and archaea are ubiquitous and can transform ammonia locked up in soil or manure into nitrate, a more soluble form of nitrogen. However, nitrifying bacteria and archaea inhabiting maize rhizosphere have not been fully explored. This study evaluates the diversity and abundance of nitrifying bacteria and archaea across different growth stages of maize using 16S amplicon sequencing. Moreover, the influence of environmental factors (soil physical and chemical properties) on the nitrifying communities was evaluated. Rhizosphere soil DNA was extracted using Nucleospin Soil DNA extraction kit and sequenced on Illumina Miseq platform. MG-RAST was used to analyze the raw sequences. The physical and chemical properties of the soil were measured using standard procedure. The results revealed 9 genera of nitrifying bacteria; Nitrospira, Nitrosospira, Nitrobacter, Nitrosovibrio, Nitrosomonas, Nitrosococcus, Nitrococcus, unclassified (derived from Nitrosomonadales), unclassified (derived from Nitrosomonadaceae) and 1 archaeon Candidatus Nitrososphaera. The Nitrospirae phyla group, which had the most nitrifying bacteria, was more abundant at the tasselling stage (67.94%). Alpha diversity showed no significant difference. However, the Beta diversity showed significant difference (p = 0.01, R = 0.58) across the growth stages. The growth stages had no significant effect on the diversity of nitrifying bacteria and archaea, but the tasselling stage had the most abundant nitrifying bacteria. A correlation was observed between some of the chemical properties and some nitrifying bacteria. The research outcome can be put into consideration while carrying out a biotechnological process that involves nitrifying bacteria and archaea.

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Tsuneda, S., Y. Ejiri, T. Nagano e A. Hirata. "Formation mechanism of nitrifying granules observed in an aerobic upflow fluidized bed (AUFB) reactor". Water Science and Technology 49, n. 11-12 (1 giugno 2004): 27–34. http://dx.doi.org/10.2166/wst.2004.0796.

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The influences of trace metals in the wastewater and shear stress by aeration were particularly examined to clarify the formation mechanism of nitrifying granules in an aerobic upflow fluidized bed (AUFB) reactor. It was found that Fe added as a trace element to the inorganic wastewater accumulated at the central part of the nitrifying granules. Another result obtained was that suitable shear stress by moderate aeration (0.07-0.20 L/min/L-bed) promoted granulation. Furthermore, it was successfully demonstrated that pre-aggregation of seed sludge using hematite promoted core formation, leading to rapid production of nitrifying granules. From these results, a nitrifying granulation mechanism is proposed: 1) as a first step, nitrifying bacteria aggregate along with Fe precipitation, and then the cores of granules are formed; 2) as a second step, the aggregates grow to be spherical or elliptical in form due to multiplication of the nitrifying bacteria and moderate shear stress in the reactor, and then mature nitrifying granules are produced. Fluorescence in situ hybridization (FISH) analysis successfully visualized the change in the spatial distribution of nitrifying bacteria in the granules, which supports the proposed granulation mechanism.

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Lai, Zi Ni, Ying De Cui, Peng Gao e Xun Jun Chen. "Modified PLA Carrier Material and its Performance in Immobilization of Nitrifying Bacteria". Materials Science Forum 610-613 (gennaio 2009): 198–201. http://dx.doi.org/10.4028/www.scientific.net/msf.610-613.198.

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To prepare the renewable carrier materials for immobilization of nitrifying bacteria, polylactic acid (PLA) dichloromethane solution was added to chitosan aqueous solution, mixed by agitation at a speed of 150 rpm / min. The resultant PLA microspheres were fund to have diameter of 100 ~ 300 μm, thus underwent ammonolysis by a 6 % hexamethylenediamine / n-propanol solution for 8 min, hydroformylation by a 1% glutaraldehyde solution for 3 h, and grafted with 1% chitosan for 24 h, to improve the surface hydrophilic property. The static adsorption was applied for adhesion of nitrifying bacteria to the surface of the carrier, i.e. immobilization of nitrifying bacteria. The removal efficiency of ammonia by the immobilized nitrifying bacteria in wastewater treatment was tested. The results showed that the surface of the microsphere carrier was rough and osteoporosis, therefore it can adhere more nitrifying bacteria. When it was immersed in the suspension of nitrifying bacteria for 8 h, the rate of nitrification by the immobilized nitrifying bacteria reached the highest level and tended to be stable afterwards.

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Okabe, Satoshi, Tomonori Kindaichi e Tsukasa Ito. "Fate of 14C-Labeled Microbial Products Derived from Nitrifying Bacteria in Autotrophic Nitrifying Biofilms". Applied and Environmental Microbiology 71, n. 7 (luglio 2005): 3987–94. http://dx.doi.org/10.1128/aem.71.7.3987-3994.2005.

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ABSTRACT The cross-feeding of microbial products derived from 14C-labeled nitrifying bacteria to heterotrophic bacteria coexisting in an autotrophic nitrifying biofilm was quantitatively analyzed by using microautoradiography combined with fluorescence in situ hybridization (MAR-FISH). After only nitrifying bacteria were labeled with [14C]bicarbonate, biofilm samples were incubated with and without NH4 + as a sole energy source for 10 days. The transfer of 14C originally incorporated into nitrifying bacterial cells to heterotrophic bacteria was monitored with time by using MAR-FISH. The MAR-FISH analysis revealed that most phylogenetic groups of heterotrophic bacteria except the β-Proteobacteria showed significant uptake of 14C-labeled microbial products. In particular, the members of the Chloroflexi were strongly MAR positive in the culture without NH4 + addition, in which nitrifying bacteria tended to decay. This indicated that the members of the Chloroflexi preferentially utilized microbial products derived from mainly biomass decay. On the other hand, the members of the Cytophaga-Flavobacterium cluster gradually utilized 14C-labeled products in the culture with NH4 + addition in which nitrifying bacteria grew. This result suggested that these bacteria preferentially utilized substrate utilization-associated products of nitrifying bacteria and/or secondary metabolites of 14C-labeled structural cell components. Our results clearly demonstrated that the coexisting heterotrophic bacteria efficiently degraded and utilized dead biomass and metabolites of nitrifying bacteria, which consequently prevented accumulation of organic waste products in the biofilm.

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Okabe, S., H. Naitoh, H. Satoh e Y. Watanabe. "Structure and function of nitrifying biofilms as determined by molecular techniques and the use of microelectrodes". Water Science and Technology 46, n. 1-2 (1 luglio 2002): 233–41. http://dx.doi.org/10.2166/wst.2002.0482.

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The phylogenetic diversity of a nitrifying bacterial community of two types of nitrifying biofilms, a domestic wastewater biofilm and an autotrophic nitrifying biofilm grown on rotating disk reactors (RDR), was characterized by 16S ribosomal DNA (rDNA)-cloning analysis. Thereafter, successional development of nitrifying the bacterial community within both biofilms was visualized in situ by fluorescent in situ hybridization (FISH) with a set of fluorescently labeled 16S rRNA-targeted DNA probes. In situ hybridization revealed that Nitrosomonas ureae was the numerically dominant species of the ammonia-oxidizing population in the domestic wastewater biofilm and that a population shift from N. urea to N. europaea and N. eutropha occurred when the culture medium was switched to the synthetic media from the domestic wastewater. After reaching the steady-state condition, microprofiles of NH4+, NO2−, NO3−, and O2 in the biofilms were measured by use of microsensors, and the spatial distributions of in situ nitrifying activities were determined. The relationship between the spatial organization of nitrifying bacterial populations and the in situ activity of these populations within the biofilms was discussed. Microelectrode measurements revealed that the active ammonia-oxidizing zone was vertically separated from the active nitrite-oxidizing zone. This vertical separation became more evident with increase of the substrate C/N ratio, leading to deterioration of nitrification efficiency. The combined use of these techniques made it possible to relate in situ nitrifying activity directly to the occurrence of nitrifying bacterial populations.

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Sarker, D. C., e A. Sathasivan. "Nitrification control by adjusting pH in severely nitrified bulkwaters". Water Supply 12, n. 5 (1 agosto 2012): 683–90. http://dx.doi.org/10.2166/ws.2012.042.

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Nitrification control is complicated and expensive, especially when nitrification has reached a severely nitrifying stage. Under this condition, utilities usually apply re-chloramination with limited success. Adjusting pH may benefit utilities. However, it is not clear whether pH should be moved up or down, and pH adjustment will also alter the chloramine decay profile (biocide) and ammonia (food) concentration. It is important to understand how this behaviour will ultimately impact nitrifying bacterial activity. We collected samples from severely nitrifying bulkwaters and adjusted the pH within a practical range to know which pH benefits the most. Results showed that even a slight increase in pH can help in protecting the chloramine residual and suppressing nitrifying bacterial activity.

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Morgan, Guillian, e Rania Hamza. "Cultivation of Nitrifying and Nitrifying-Denitrifying Aerobic Granular Sludge for Sidestream Treatment of Anaerobically Digested Sludge Centrate". Processes 10, n. 9 (25 agosto 2022): 1687. http://dx.doi.org/10.3390/pr10091687.

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In this study, three 1.2-L aerobic granular sludge sequencing batch reactors (AGS-SBRs) were used to cultivate nitrifying and nitrifying-denitrifying granules (w/supplemental carbon) and investigate sidestream treatment of synthetic-centrate and real-centrate samples from Ashbridges Bay Treatment Plant (ABTP) in Toronto, Ontario, Canada. Results showed that although the cultivation of distinct granules was not observed in the nitrifying reactors, sludge volume index (SVI30) values achieved while treating real and synthetic centrate were 72 ± 12 mL/g and 59 ± 11 mL/g (after day 14), respectively. Ammonia-nitrogen (NH3-N) removal in the nitrifying SBRs were 93 ± 19% and 94 ± 16% for real and synthetic centrate, respectively. Granules with a distinct round structure were successfully formed in the nitrifying-denitrifying SBR, resulting in an SVI30 of 52 ± 23 mL/g. NH3-N, chemical oxygen demand (COD) and phosphorus (P) removal in the nitrifying-denitrifying SBR were 92 ± 9%, 94 ± 5%, and 81 ± 14% (7th to 114th day), respectively with a low nitrite (NO2-N) and nitrate (NO3-N) concentration in the effluent indicating simultaneous nitrification-denitrification (SND) activity. High nutrient removal efficiencies via the nitrification and SND pathways shows that AGS technology is a viable process for treating sidestreams generated in a WWTP.

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Blew, R. D., e D. Parkinson. "Nitrification and denitrification in a white spruce forest in southwest Alberta, Canada". Canadian Journal of Forest Research 23, n. 8 (1 agosto 1993): 1715–19. http://dx.doi.org/10.1139/x93-214.

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Nitrification and denitrification were measured in a 120-year-old Piceaglauca (Moench) Voss forest in southwestern Alberta. Nitrifying activity could not be detected using short-term incubations of F–H and upper mineral soil horizons. Long-term incubations for nitrifying potential indicated that nitrifying organisms were present. The results suggest that the population of nitrifying organisms must have been small, their activity was limited, or the microhabitat necessary for their activity was not adequately simulated by the soil slurries in the short-term incubations. Low rates of denitrification were detected but probably did not represent a substantial loss of N from the soil–plant system. Low rates of denitrification may have been due to a lack of substrate (NO3−), reflecting the low rates of nitrification.

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Fdz-Polanco, F., S. Villaverde e P. A. García. "Temperature effect on nitrifying bacteria activity in biofilters: activation and free ammonia inhibition". Water Science and Technology 30, n. 11 (1 dicembre 1994): 121–30. http://dx.doi.org/10.2166/wst.1994.0552.

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Nitrifying bacteria activity and concentrations depend on specific free ammonia concentration (ratio NH3/biomass), that is a function of temperature, pH, ammonium concentration and nitrifying biomass concentration. So, temperature is a key parameter in the nitrification process producing two opposite effects: bacteria activation and free ammonia inhibition. These phenomena are studied in an up-flow biological aerated filter (UBAF) settled by a nitrifying biofilm (measured as Volatile Attached Solids, VAS). The plug flow allows to disclosure of both effects, activation and inhibition. For Nitrosomonas bacteria only an activation effect was observed; their activity reaches a maximum at 28-29 °C. For Nitrobacter the free ammonia inhibition prevails against the activation effect for values greater than 1 mg N-NH3/mg VAS allowing nitrite accumulation of 80%; this inhibition threshold value for nitrifying biofilm is obtained measuring the specific rate of utilization of substratum per unit of biomass (μmax/Y) by activity test. The knowledge of this threshold in a biofilm process is fundamental in order to control the nitrite accumulation in nitrifying biofilm reactors.

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Hasebe, Yoshiaki, Hiroaki Meguro, Yuuki Kanai, Masahiro Eguchi, Toshifumi Osaka e Satoshi Tsuneda. "High-rate nitrification of electronic industry wastewater by using nitrifying granules". Water Science and Technology 76, n. 11 (7 settembre 2017): 3171–80. http://dx.doi.org/10.2166/wst.2017.431.

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Abstract Nitrifying granules have a high sedimentation property and an ability to maintain a large amount of nitrifying bacteria in a reaction tank. Our group has examined the formation process of nitrifying granules and achieved high-rate nitrification for an inorganic synthetic wastewater using these granules. In this research, a pilot-scale test plant with an 850-liter reaction tank was assembled in a semiconductor manufacturing factory in order to conduct a continuous water conduction test using real electronics industry wastewater. The aim was to observe the formation of nitrifying granules and determine the maximum ammonia removal rate. The average granule diameter formed during the experiment was 780 μm and the maximum ammonia removal rate was observed to be 1.5 kgN·m−3·day−1 at 20 °C, which is 2.5–5 times faster than traditional activated sludge methods. A fluorescence in situ hybridization analysis showed that β-proteobacterial ammonia oxidizing bacteria and the Nitrospira-like nitrite-oxidizing bacteria dominate the bacteria population in the granules, and their strong aggregation capacity might confer some benefits to the formation of these nitrifying granules.

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Ding, Yuan Hong, Qing Wang, Hong Qiang Ren e Jian Lu. "Effects of Trichloroethylene on the Wastewater Treatment in Membrane Bioreactors". Advanced Materials Research 588-589 (novembre 2012): 34–38. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.34.

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The activities of nitrifying bacteria and organic utilizing bacteria against TCE in sludge was investigated using three series of Membrane bioreactors, and the results indicated that, the removal efficiencies of COD decreased gradually, but was not affected severely with TCE inhibition, good organics removal efficiencies was possibly realized, while the ammonia removal efficiencies dropped sharply due to the severe inhibition of TCE against nitrifying bacteria, the degree of TCE inhibition against nitrifying bacteria increased with the TCE concentration, but low-concentration TCE addition seems act as a chronic toxicity to the sludge activity, However, the nitrifying bacteria was gradually adapted to the TCE inhibition and its activities could be entirely resumed, and the ability of the nitrifying sludge to tolerate TCE could be satisfactory maintained either after the stop of TCE addition, therefore, TCE could be degradated partly by the nitrification processes, when the TCE was added intermittently and continuously into the Membrane reactors, simultaneously, a good performance of nitrification and organic utilization processes was possibly maintained stably.

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Han, Dengfeng, Zhenyi Hu, Dapeng Li e Rong Tang. "Nitrogen Removal of Water and Sediment in Grass Carp Aquaculture Ponds by Mixed Nitrifying and Denitrifying Bacteria and Its Effects on Bacterial Community". Water 14, n. 12 (9 giugno 2022): 1855. http://dx.doi.org/10.3390/w14121855.

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Nitrification and denitrification are important for nitrogen (N) cycling in fish ponds culture, but the effects of nitrifying and denitrifying bacteria concentrations on pond water and sediments remain largely unknown. Here, we used 0, 0.15, 0.30, 0.60 mg/L different concentrations of mixed nitrifying and denitrifying bacteria to repair the pond substrate through an enclosure experiment lasting 15 days. The results showed that the purification effect of nitrifying and denitrifying bacteria was most obvious on pond nitrogen from day 4 to day 7. The optimal relative concentration was 0.60 mg/L for nitrifying and denitrifying bacteria; NH4+-N (ammonia nitrogen) decreased by 75.83%, NO2−-N (nitrite) by 93.09%, NO3−-N (nitrate) by 38.02%, and TN (total nitrogen) by 45.16% in this concentration group on pond water. In one cycle, C/N (carbon/nitrogen) ratio of both water body and bottom sediment significantly increased, but C/N ratio of water body increased more significantly than that of sediment. Water C/N ratio increased by 76.00%, and sediment C/N ratio increased by 51.96% in the 0.60 mg/L concentration group. Amplicon sequencing of pond sediment showed that the change in nitrifying and denitrifying bacterium diversity was consistent with that in water quality index. Dominant nitrifying bacteria had a relatively high percentage, with significant differences in dominant bacterium percentage across different bacterial addition groups, while dominant denitrifying bacterium percentage was not high without significant differences among different groups. The dominant species of nitrifying bacteria were, respectively, Nitrosomonas, Nitrosovibrio, Nitrosospira, and Aeromonas, and the dominant species of denitrifying bacteria were Thauera, Azoarcus, Magnetospirillum, Azospira, and Idiomarina. The correlation analyses showed an aerobic nitrification and facultative anaerobic denitrification in pond sediments. Research shows that the addition of exogenous nitrifying and denitrifying bacteria can effectively reduce the nitrogen load of pond water and sediment. At the concentration of 0.6 mg/L, the nitrogen load of pond water and sediment decreased most obviously, which had the best effect on pond purification.

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Ikuta, H., N. Noda, Y. Ebie, A. Hirata, S. Tsuneda, M. Matsumura e Y. Inamori. "The rapid quantification and detection of nitrifying bacteria by using monoclonal antibody method". Water Science and Technology 42, n. 3-4 (1 agosto 2000): 1–7. http://dx.doi.org/10.2166/wst.2000.0351.

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Monoclonal antibodies against the two kinds of nitrifying bacteria Nitrosomonas europaea (IFO14298) and Nitrobacter winogradskyi (IFO14297) were raised and isotypes of these monoclonal antibodies, IgM and IgG1, were successfully obtained. Cross reactivities of these monoclonal antibodies against various kinds of representative heterotrophic bacteria turned out to be relatively low by competitive ELISA. In contrast, these monoclonal antibodies were very specific for nitrifying bacteria used as antigens. By means of sandwich ELISA using different isotype monoclonal antibodies such as IgM and IgG1, calibration curves were successfully developed for quantification of nitrifying bacteria. It was shown that the obtainable lower limit of quantification of N. europaea and N. winogradskyi were 7.0 × 106 N/ml and were 6.0 × 105 N/ml, respectively. Nitrifying bacteria in activated sludge of advanced domestic wastewater treatment johkaso were counted by sandwich ELISA and MPN methods. The bacterial number estimated by MPN method was lower than that estimated by sandwich ELISA. It was indicated that this monoclonal antibody method could be used as a quick and powerful tool for estimating and controlling the population of nitrifying bacteria in the advanced domestic wastewater treatment processes.

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Ren, Baisha, Bradley Young, Fabio Variola e Robert Delatolla. "Protein to polysaccharide ratio in EPS as an indicator of non-optimized operation of tertiary nitrifying MBBR". Water Quality Research Journal 51, n. 4 (14 marzo 2016): 297–306. http://dx.doi.org/10.2166/wqrjc.2016.040.

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The protein (PN), polysaccharide (PS), and extracellular DNA (eDNA) percent concentrations of extracellular polymeric substances (EPS) of biofilm samples harvested from a pilot-scale nitrifying moving bed biofilm reactor (MBBR) were investigated at various operating temperatures and hydraulic retention times (HRTs). Chemically measured EPS PN/PS ratios were shown to correlate to Raman intensity ratios of amide III to carbohydrate at 362 rel. cm−1. The study also demonstrates that tertiary nitrifying MBBR systems may be optimized to operate at HRTs as low as 0.75 to 1.0 h as opposed to conventional HRTs of 2.0 to 6.0 h. The EPS of the nitrifying MBBR biofilm exhibited the lowest percent PN content and the highest percent PSs and eDNA content. In particular, PN/PS ratios lower than 3 were indicative of non-optimal operation of the nitrifying MBBR systems, whereas PN/PS ratios with values significantly below 3 were observed for ammonia underloaded systems at high operating temperatures and hydraulically overloaded systems at low HRTs. This study demonstrates that the PN/PS ratio in EPS is a potential metric to identify non-optimal operation of nitrifying MBBR systems.

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Tanaka, Kazuhiro, Minoru Tada, Takashi Kimata, Shouji Harada, Yuhko Fujii, Tamotu Mizuguchi, Naomichi Mori e Hiroyoshi Emori. "Development of New Nitrogen Removal System Using Nitrifying Bacteria Immobilized in Synthetic Resin Pellets". Water Science and Technology 23, n. 4-6 (1 febbraio 1991): 681–90. http://dx.doi.org/10.2166/wst.1991.0518.

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A newly developed process applying a technique of microorganism immobilization to biological nitrogen removal is reported. Nitrifiers immobilized in 2 to 3 mm diameter polyethylene-glycol resin (Nitrifying pellets) are mixed with activated sludge in the nitrification tanks to promote quick nitrification. Due to the high nitrifying activity of the pellets, nitrification of municipal wastewaters is completed within a few hours. This paper introduces the synthetic polymer and immobilization method suited to nitrifiers, the conditions for pellet fluidization, the activity of nitrifying pellets and its treatment performance as a nitrogen removal process.

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Liu, Yu, e Bernard Capdeville. "Dynamics of Nitrifying Biofilm Growth in Biological Nitrogen Removal Process". Water Science and Technology 29, n. 7 (1 aprile 1994): 377–80. http://dx.doi.org/10.2166/wst.1994.0365.

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A conventional laboratory scale annular reactor was employed to investigate the dynamics of nitrifying biofilm growth. A dense and thin nitrifying biofilm was developed in this study. The results showed that the active growth of the nitrifying biofilm can be characterized best by the increase of the specific substrate removal rate until a maximum value, at which the maximum active film thickness and active biomass were attained. It was found that non active biomass accumulation directly resulted in the reduction in the specific ammonium nitrogen removal rate, however the ammonium nitrogen surface removal rate was not affected by the additional biomass accumulation. As a result, the credibility of the classic method using the substrate surface removal rate to estimate the maximum active film thickness was doubted. It was expected that thinner nitrifying biofilm ranging from 20 to 30µm has a higher specific nitrification rate to be 9.0mgNH4+-N/mgCOD-biomass/day.

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Liang, Wan Ting, e Peng Tian. "Determination Content of Zinc Element in Natural Huazi Mushroom by ICP-AES". Applied Mechanics and Materials 707 (dicembre 2014): 176–79. http://dx.doi.org/10.4028/www.scientific.net/amm.707.176.

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Zinc is an essential trace element, zinc content in human body is 1.4~2.3g, is widely distributed in various tissues, including skeletal and skin are more, the nutritional status of zinc content in hair Znn reflect the long-term supply of dietary zinc level and human zinc. Using the high pressure nitrifying pot method and wet method and treatment of samples were determined in natural Huazi Mushroom samples Zn element content. High pressure nitrifying pot method relative standard deviation of Zn element is 5.82%; Wet method to determine the relative standard deviation of Zn elementt is 4.81%. Visible high pressure nitrifying pot method and treatment of samples of precision of the measuring precision and wet processing samples are relatively low. By comparison, high pressure nitrifying pot method specific humidity method to deal with the sample good measuring precision, higher accuracy, and the measurement process to save time.

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Azimi, Y., X. Chen, D. G. Allen, V. Pileggi, P. Seto, I. G. Droppo e R. R. Farnood. "UV disinfection of wastewater flocs: the effect of secondary treatment conditions". Water Science and Technology 67, n. 12 (1 giugno 2013): 2719–23. http://dx.doi.org/10.2166/wst.2013.148.

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Activated sludge flocs that are carried to the final effluent can significantly decrease the effectiveness of ultraviolet (UV) disinfection of wastewater. This effect is detected in a typical UV dose–response curve, where at higher UV doses there is a decrease in the inactivation rate (tailing). In this study, the effect of activated sludge process conditions on the UV inactivation kinetics of flocs was investigated. The conditions compared were nitrifying vs. non-nitrifying vs. an enhanced biological nutrient removal–University of Cape Town (BNR-UCT) system. The results showed that the flocs generated in the BNR-UCT process were easier to disinfect. The final effluent from the BNR-UCT process also showed improved kinetics of inactivation and reached higher levels of disinfection. The nitrifying system's final effluent had a lower number of initial fecal coliforms, which contributed to reaching higher disinfection levels compared to the non-nitrifying system.

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Pérez-Alfaro, J. E., G. González-Blanco, E. Sierra-Palacios, J. Marcial-Quino e R. Beristain-Cardoso. "Acclimation of nitrifying biomass and its effect on 2-chlorophenol removal". Water Science and Technology 71, n. 2 (11 dicembre 2014): 277–82. http://dx.doi.org/10.2166/wst.2014.508.

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The metabolic and kinetic behavior of a nitrifying sludge exposed to 2-chlorophenol (2-CP) was evaluated in batch cultures. Two kinds of nitrifying culture were used; one acclimated to 4-methylphenol (4-mp), and the other unacclimated to 4-mp. The unacclimated culture was affected adversely by the 2-CP's presence, since neither nitrification nor 2-CP oxidation was observed. Nonetheless, the acclimated culture showed metabolic capacity to nitrify and mineralize 2-CP. Ammonium removal was 100%, with a nitrifying yield of 0.92 ± 0.04 mg NO3−-N/mg NH4+-N consumed. The consumption efficiency for 2-CP was 100% and the halogenated compound was mineralized to CO2. Denaturing gradient gel electrophoresis (DGGE) patterns showed the shift in microbial community structure, indicating that microbial diversity was due to the acclimation process. This is the first evidence where nitrifying culture acclimated to 4-mp completely removed ammonium and 2-CP.

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Dong, Ziyi, Changhao Xiao, Weihua Zeng e Jinbo Zhao. "Impact of 17β-Estradiol on Natural Water’s Heterotrophic Nitrifying Bacteria". International Journal of Environmental Science and Development 12, n. 1 (2021): 17–22. http://dx.doi.org/10.18178/ijesd.2021.12.1.1312.

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In this research, bottom water samples were collected from nature water. After cultivating and selecting, bacteria which could use (NH4)2SO4 as the only nitrogen source had been selected. The bacteria in different cultures with different concentration of 17β-estradiol (E2) were cultivated, and every group’s concentration of N-NH4 +, N-NO3 - and OD600 were measured. The result shows that compare with the control group, in which no E2 was added, the growth of heterotrophic nitrifying bacteria had been promoted when the concentration of E2 was in range of 1-100 ng/L. In addition, heterotrophic nitrifying bacteria’s growing speed has a positive correlation between the E2’s concentration. However, low concentration of E2 (like 0.1 ng/L), could inhibit the growth of heterotrophic nitrifying bacteria. Considering the impact of E2 on heterotrophic nitrifying bacteria, it is necessary to intensify the detection to E2 in the future.

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Liu, Fang, Xin Zhao, Yujin Pan e Xiaomin Hu. "CONSTRUCTION OF NITRIFICATION MODEL WITH NITRIFYING COAL ASH IN AEROBIC TREATMENT OF HIGH STRENGTH WASTEWATER". Journal of Environmental Engineering and Landscape Management 30, n. 4 (16 dicembre 2022): 508–14. http://dx.doi.org/10.3846/jeelm.2022.18061.

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Nitrifying carriers can provide good settle ability and stable removal efficiency for nitrogen. Models for ammonia removal rate for nitrifying carriers will improve its engineering application. This study was conducted in nitrifying coal ash system with Monod model. Results indicated the maximum NH4+-N removal rate and half-saturation constant of NH4+-N in Monod model were 110.48 mg/L and 59.19 mg/L, respectively. Introduction of the correction coefficients, including pH, temperature and dissolved oxygen (DO) concentration, decreased the average gap between experiment data and simulated data from 6.48 to 2.74 mg N/(L·h). And improved accuracy of the Monod model by 5.11%. The differences between experiment and simulated NH4+-N removal rate ranged from 0.08 mg N/(L·h) to 8.34 mg N/(L·h) when the influent concentration of NH4+-N increased from 443.18 to 1121.29 mg N/L and without organic. Only 0.08% inconsistency between experiment and simulated data occurred in treating wastewater with high-strength ammonia. However, NH4+-N removal rate of the nitrifying coal ash was inhibited about 40% when influent with averaged 173.19 mg COD/L and 37.20 mg N/L, therefore, other factors, the content of nitrifying bacteria for example, need to be introduced into the Monod model when treating organic wastewater.

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Wang, Zhu, Bo Liu e Ai Min Li. "Effects of Adding Nitrifying Bacteria on Microbial Communities and Nitrification in a Laboratory-Scale a/O Reactor Treating Leather-Tanning Wastewater". Advanced Materials Research 599 (novembre 2012): 289–94. http://dx.doi.org/10.4028/www.scientific.net/amr.599.289.

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Abstract (sommario):

A laboratory-scale anoxic/oxic reactor was used to analyze the effects of adding nitrifying bacteria on microbial communities in the treatment of leather-tanning wastewater. The reactor was operated in series in continuous flow mode for 25 d after an acclimation period of 45 d, and the nitrifying bacteria were added after the acclimation period. The addition of nitrifying bacteria into the wastewater significantly enhanced NH4+-N removal efficiency. The Arrhenius and Jacob-Monod models were applied to determine the optimum and acceptable operating conditions for this process. The optimum temperature range and concentration of dissolved oxygen were 15-30 oC and 5 mg L-1, respectively. Use of Nitrosomonas europaea and Nitrobacter were considered reliable for leather-tanning wastewater treatment due to their dominant status as nitrifying bacteria. Substrate half-saturation constants for ammonia oxidizing bacteria and nitrite oxidizing bacteria were 24.13 mg L-1 and 5.43 mg L-1, respectively.

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23

Xu, Ting Ting, e Peng Tian. "Determination of Iron Element in Comb Mushroom by ICP-AES". Applied Mechanics and Materials 707 (dicembre 2014): 172–75. http://dx.doi.org/10.4028/www.scientific.net/amm.707.172.

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Abstract (sommario):

Iron is indispensable to make hemoglobin and other iron material elements, is also necessary to exchange and oxygen in the blood of an element, many organisms in REDOX system cannot leave it. Most of the iron distribution in special cells in the body. Using the high pressure nitrifying pot method and wet method and treatment of samples were determined in Comb Mushroom samples Fe element content, the determination results are shown in table 2. High pressure nitrifying pot method relative standard deviation of Fe element is 3.689%; Wet method to determine the relative standard deviation of Fe elementt is 5.473%. Visible high pressure nitrifying pot method and treatment of samples of precision of the measuring precision and wet processing samples are relatively good, the measuring precision of the former better. By comparison, high pressure nitrifying pot method specific humidity method to deal with the sample good measuring precision, higher accuracy, and the measurement process to save time.

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24

Xu, Wujie, Yu Xu, Haochang Su, Xiaojuan Hu, Keng Yang, Guoliang Wen e Yucheng Cao. "Characteristics of Ammonia Removal and Nitrifying Microbial Communities in a Hybrid Biofloc-RAS for Intensive Litopenaeus vannamei Culture: A Pilot-Scale Study". Water 12, n. 11 (26 ottobre 2020): 3000. http://dx.doi.org/10.3390/w12113000.

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Abstract (sommario):

Ammonia is the main pollution factor of the aquatic environment in marine shrimp culture systems. In order to demonstrate the feasibility of the combination of biofloc technology and nitrifying biofilter for the ammonia removal, a 70-day production trial was conducted in a simplified pilot-scale hybrid biofloc-based recirculating aquaculture system (biofloc-RAS) with the intensive culture of Litopenaeus vannamei. Nitrogen dynamics and nitrifying microbial communities were investigated in three replicated systems simultaneously under the conditions of high feed loading and zero water exchange. Along with biofloc development in the culture tank and biofilm formation in the nitrifying biofilter during the trial, nitrification could be fastly and effectively established in the system, which was indicated by the dynamics of total ammonia nitrogen (TAN), NO2–-N, NO3–-N, and total nitrogen (TN) concentrations. Meanwhile, similar nitrifying microorganisms could be found between biofloc and biofilm, despite some differences in abundance, diversity, and composition of ammonia-oxidizing archaea and bacteria and nitrite-oxidizing bacteria. High TAN removal rate could be achieved and was significantly and positively correlated with abundances of these nitrifying microbial communities in both biofloc and biofilm, further indicating that both biofloc and biofilm could contribute highly to nitrification performance of the biofloc-RAS. The results of this study indicate a potential application of the biofloc-RAS in coastal intensive aquaculture.

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25

Tsuneda, S., M. Ogiwara, Y. Ejiri e A. Hirata. "High-Rate Nitrification Using Aerobic Granular Sludge". Water Science and Technology 53, n. 3 (1 febbraio 2006): 147–54. http://dx.doi.org/10.2166/wst.2006.087.

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Abstract (sommario):

The performance of nitrifying granules, which had been produced in an aerobic upflow fluidised bed (AUFB) reactor, was investigated in various types of ammonia-containing wastewaters. When pure oxygen was supplied to the AUFB reactor with a synthetic wastewater containing a high concentration of ammonia (500 g-N/m3), the ammonia removal rate reached 16.7 kg-N/m3/day with a sustained ammonia removal efficiency of more than 80%. The nitrifying granules possessing a high settling ability could be retained with a high density (approximately 10,000 g-MLSS/m3) in a continuous stirring tank reactor (CSTR) even under a short hydraulic retention time (44 min), which enabled a high-rate and stable nitrification for an inorganic wastewater containing low concentrations of ammonia (50 g-N/m3). Moreover, the nitrifying granules exhibited sufficient performance in the nitrification of real industrial wastewater containing high concentrations of ammonia (1,000–1,400 g-N/m3) and salinity (1.2–2.2%), which was discharged from metal-refinery processes. When the nitrifying granules were used in cooperation with activated sludge to treat domestic wastewater containing organic pollutants as well as ammonia, they fully contributed to nitrification even though a part of activated sludge adhered onto the granule surfaces to form biofilms. These results show the wide applicability of nitrifying granules to various cases in the nitrification step of wastewater treatment plants.

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26

Tsuneda, S., T. Miyoshi, Y. Aoi e A. Hirata. "Tailoring of highly efficient nitrifying biofilms in fluidized bed for ammonia-rich industrial wastewater treatment". Water Science and Technology 42, n. 3-4 (1 agosto 2000): 357–62. http://dx.doi.org/10.2166/wst.2000.0403.

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Abstract (sommario):

We proposed two tailoring methods for efficient nitrifying biofilms on particles which are expected to be used in fluidized bed in nitrogen removal processes for industrial wastewaters. The first method was examined with gradual reduction of the hydraulic retention time in continuous feeding reactor to form biofilm with high nitrification ability. As a result, nitrification rate was successfully improved mainly due to acclimation of nitrifying bacteria to higher loading. The second tailoring method for nitrifying biofilm started with the biofilm which had been previously constructed in synthetic domestic wastewater containing high concentration of NH4+-N as well as various biodegradable organic compounds. Stepwise reduction of C/N ratio in inlet wastewater was performed during one month simultaneously with observation of microbial population dynamics in the biofilm using fluorescent in situ hybridization (FISH) analysis. As a result, this acclimation process promoted occupation of the biofilm by ammonia-oxidizing bacteria and resulted in making suitable biofilm structure for nitrification of ammonia-rich industrial wastewater. Moreover, it is confirmed that this new tailoring method greatly shortened required time to obtain nitrifying biofilms.

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27

Sheng, Xiaolin, Rui Liu, Lujun Chen, Zihua Yin e Jianfeng Zhu. "Enrichment and application of nitrifying activated sludge in membrane bioreactors". Water Science and Technology 76, n. 11 (14 agosto 2017): 2888–94. http://dx.doi.org/10.2166/wst.2017.421.

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Abstract (sommario):

Abstract In this study, nitrifying bacteria were enriched in a membrane bioreactor (MBR, R1) and their bioaugmentation effectiveness was evaluated in another two MBRs (R2 and R3). Nitrifying activated sludge (NAS) with high nitrification activity of up to 3,000 mg-N/(L·d)−1 was successfully enriched in R1. The results showed that chemical oxygen demand concentration of 100–200 mg/L had no negative effect on NAS enrichment but reduced the ratio of bacterial nitrifiers. Moreover, the cell concentration of nitrifying bacteria in NAS, which was 3.1 × 1011 cells/L, was similar to that of the commercial bacterium agent. For the bioaugmentation test, the reactor inoculated with 14% NAS achieved a 23% higher NH4+-N removal efficiency than that of the uninoculated reactor. Along with the improvement of nitrification performance, the bacterial nitrifiers abundance and microbial richness remarkably increased after bioaugmentation. These results suggested that the MBR system could efficiently enrich nitrifying bacteria using organic carbon containing culture medium, and potentially act as a side-stream reactor to enhance the nitrification function of the wastewater treatment plant.

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28

Inamori, Yuhei, Tomotake Takai, Naohiro Noda, Akira Hirata, Hiroshi Niioka, Gao YueHua e Masatoshi Matsumura. "Development of a rapid quantification method for nitrosomonas and nitrobacter using elisa for wastewater treatment facilities". Water Science and Technology 36, n. 12 (1 dicembre 1997): 169–74. http://dx.doi.org/10.2166/wst.1997.0444.

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Abstract (sommario):

Enzyme-linked immunosorbent assay (ELISA) by use of monoclonal antibodies (MAbs) is very useful and helpful for the detection and quantification of the specific bacteria like nitrifiers in a mixed bacterial habitat. In this study, seven monoclonal antibodies were raised from splenocytes of mice(BALB/c) that are specific for the surface antigen of the two kinds of nitrifying bacteria. Three were directed against Nitrosomonas europaea (IFO 14298) and four were directed against Nitrobacter winogradskyi (IFO 14297). Cross-reactivities of MAbs against other strains of nitrifying bacteria as well as some kinds of representative heterotrophic bacteria in activated sludge and biofilm were checked to determine the usefulness of MAbs. It was found that there were some strain specificities between the same genera of IFO and ATCC strain. By means of a competitive ELISA, correlation curves for quantifying nitrifying bacteria were developed in a pure culture. It was found that this monoclonal antibody method could be used as a quick and powerful tool for estimating and controlling the population of nitrifying bacteria.

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29

Bai, Xue, Haixin Gu e Yulong Li. "Coimmobilized Microalgae and Nitrifying Bacteria for Ammonium Removal". International Journal of Environmental Science and Development 7, n. 6 (2016): 406–9. http://dx.doi.org/10.7763/ijesd.2016.v7.809.

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30

Boller, M., W. Gujer e M. Tschui. "Parameters affecting nitrifying biofilm reactors". Water Science and Technology 29, n. 10-11 (1 ottobre 1994): 1–11. http://dx.doi.org/10.2166/wst.1994.0739.

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Abstract (sommario):

The variables affecting nitrification in biofilms are identified on a theoretical basis. The influence of various design and operational parameters which affect the resulting substance fluxes into and out of the biofilm and the biomass activity regarding nitrification are illustrated with the help of experimental investigations with plastic media trickling filters, rotating biological contactors and different aerated biofilters. The results of experiments with these systems in tertiary nitrification applications reveal process limitations and technical measures to enhance nitrification performance in each system. In a case study, a comparison between the different biofilm processes and activated sludge alternatives showed that biofilm systems may lead to remarkably smaller reactor volumes, but high energy consumption due to unfavorable oxygen utilization.

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31

Andersson, B., H. Aspegren, D. S. Parker e M. P. Lutz. "High rate nitrifying trickling filters". Water Science and Technology 29, n. 10-11 (1 ottobre 1994): 47–52. http://dx.doi.org/10.2166/wst.1994.0744.

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Abstract (sommario):

A two year pilot plant study has been performed in order to evaluate a nitrifying trickling filter (NTF) process within an upgrading project for increased nutrient removal. The operation of the filters was very stable without upsets due to predators. The filter microfauna was dominated by worms and the presence of filter fly larvae was limited. Suggested predator control methods like flooding or varying the flushing intensity did not affect the identified microfauna. By operating the filters in a two stage alternating series filtration mode, higher nitrification rates and lower effluent ammonia concentrations could be reached simultaneously in comparison to operating the filters in a single stage filtration mode.

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32

Wall, David, Daressa Frodsham e Dougie Robinson. "DESIGN OF NITRIFYING TRICKLING FILTERS". Proceedings of the Water Environment Federation 2002, n. 13 (1 gennaio 2002): 340–56. http://dx.doi.org/10.2175/193864702784163326.

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33

Abeliovich, Aharon. "Nitrifying Bacteria in Wastewater Reservoirs". Applied and Environmental Microbiology 53, n. 4 (1987): 754–60. http://dx.doi.org/10.1128/aem.53.4.754-760.1987.

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34

Furukawa, Kenji, Akiko Ike e Masanori Fujita. "Preparation of marine nitrifying sludge". Journal of Fermentation and Bioengineering 76, n. 2 (gennaio 1993): 134–39. http://dx.doi.org/10.1016/0922-338x(93)90070-o.

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35

Szwerinski, H., E. Arvin e P. Harremoës. "pH-decrease in nitrifying biofilms". Water Research 20, n. 8 (agosto 1986): 971–76. http://dx.doi.org/10.1016/0043-1354(86)90038-2.

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36

Hill, Dennis R., e Terry Webster. "High pH Inhibits Nitrifying Bacteria". Opflow 34, n. 7 (luglio 2008): 20–22. http://dx.doi.org/10.1002/j.1551-8701.2008.tb02000.x.

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37

Head, M. A., e J. A. Oleszkiewicz. "SHORT SRT NITRIFICATION THROUGH SEEDING NITRIFYING BACTERIA INTO COLD, NON-NITRIFYING SEQUENCING BATCH REACTORS". Proceedings of the Water Environment Federation 2002, n. 11 (1 gennaio 2002): 85–99. http://dx.doi.org/10.2175/193864702784900534.

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38

Hill, Robert R., Dennis P. Cafferty, Wesley A. Mautz, Lou R. Sirois, Robert A. Gillette, Mary C. Lee e Heinrich O. Buhr. "NITRIFYING VERSUS NON-NITRIFYING OPERATION AT THE EL TORO WATER DISTRICT ACTIVATED SLUDGE PLANT". Proceedings of the Water Environment Federation 2000, n. 11 (1 gennaio 2000): 286–97. http://dx.doi.org/10.2175/193864700784544325.

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39

Agogué, Hélène, Maaike Brink, Julie Dinasquet e Gerhard J. Herndl. "Major gradients in putatively nitrifying and non-nitrifying Archaea in the deep North Atlantic". Nature 456, n. 7223 (26 novembre 2008): 788–91. http://dx.doi.org/10.1038/nature07535.

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40

Tran, Hung-Thuan, Dae-Hee Kim, Se-Jin Oh, Kashif Rasool, Doo-Hyun Park, Rui-Hong Zhang e Dae-Hee Ahn. "Nitrifying biocathode enables effective electricity generation and sustainable wastewater treatment with microbial fuel cell". Water Science and Technology 59, n. 9 (1 maggio 2009): 1803–8. http://dx.doi.org/10.2166/wst.2009.209.

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Abstract (sommario):

Simultaneous organics removal and nitrification using a novel nitrifying biocathode microbial fuel cell (MFC) reactor were investigated in this study. Remarkably, the introduction of nitrifying biomass into the cathode chamber caused higher voltage outputs than that of MFC operated with the abiotic cathode. Results showed the maximum power density increased 18% when cathode was run under the biotic condition and fed by nitrifying medium with alkalinity/NH4+-N ratio of 8 (26 against 22 mW/m2). The voltage output was not differentiated when NH4+-N concentration was increased from 50 to 100 mg/L under such alkalinity/NH4+-N ratio. However, interestingly, the cell voltage rose significantly when the alkalinity/NH4+-N ratio was decreased to 6. Consequently, the maximum power density increased 68% in compared with the abiotic cathode MFC (37 against 22 mW/m2). Polarization curves demonstrated that both activation and concentration losses were lowered during the period of nitrifying biocathode operation. Ammonium was totally nitrified and mostly converted to nitrate in all cases of the biotic cathode conditions. High COD removal efficiency (98%) was achieved. In light of the results presented here, the application of nitrifying biocathode is not only able to integrate the nitrogen and carbon removal but also to enhance the power generation in MFC system. Our system can be suggested to open up a new feasible way for upgrading and retrofitting the existing wastewater treatment plant by the use of MFC-based technologies.

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41

Schramm, Andreas, Dirk de Beer, Johan C. van den Heuvel, Simon Ottengraf e Rudolf Amann. "Microscale Distribution of Populations and Activities ofNitrosospira and Nitrospira spp. along a Macroscale Gradient in a Nitrifying Bioreactor: Quantification by In Situ Hybridization and the Use of Microsensors". Applied and Environmental Microbiology 65, n. 8 (1 agosto 1999): 3690–96. http://dx.doi.org/10.1128/aem.65.8.3690-3696.1999.

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Abstract (sommario):

ABSTRACT The change of activity and abundance of Nitrosospiraand Nitrospira spp. along a bulk water gradient in a nitrifying fluidized bed reactor was analyzed by a combination of microsensor measurements and fluorescence in situ hybridization. Nitrifying bacteria were immobilized in bacterial aggregates that remained in fixed positions within the reactor column due to the flow regimen. Nitrification occurred in a narrow zone of 100 to 150 μm on the surface of these aggregates, the same layer that contained an extremely dense community of nitrifying bacteria. The central part of the aggregates was inactive, and significantly fewer nitrifiers were found there. Under conditions prevailing in the reactor, i.e., when ammonium was limiting, ammonium was completely oxidized to nitrate within the active layer of the aggregates, the rates decreasing with increasing reactor height. To analyze the nitrification potential, profiles were also recorded in aggregates subjected to a short-term incubation under elevated substrate concentrations. This led to a shift in activity from ammonium to nitrite oxidation along the reactor and correlated well with the distribution of the nitrifying population. Along the whole reactor, the numbers of ammonia-oxidizing bacteria decreased, while the numbers of nitrite-oxidizing bacteria increased. Finally, volumetric reaction rates were calculated from microprofiles and related to cell numbers of nitrifying bacteria in the active shell. Therefore, it was possible for the first time to estimate the cell-specific activity of Nitrosospira spp. and hitherto-uncultured Nitrospira-like bacteria in situ.

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42

Schramm, Andreas, Dirk De Beer, Han van den Heuvel, Simon Ottengraf e Rudolf Amann. "In situ structure/function studies in wastewater treatment systems". Water Science and Technology 37, n. 4-5 (1 febbraio 1998): 413–16. http://dx.doi.org/10.2166/wst.1998.0681.

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Abstract (sommario):

As an example of the importance and the potential of in situ structure/function studies, nitrifying aggregates from different zones of a lab-scale fluidised bed reactor were analysed by microelectrode measurements of O2, NH4+, NO2−, and NO3− and in situ hybridisation targeting the 16S rRNA of the nitrifying bacteria. A shift from an ammonia oxidising to a nitrite oxidising community is present along the reactor. In the single aggregates an active nitrifying shell of about 100 μm could be related to the maximum abundance of nitrifiers in this zone. Interestingly, the main actors in this system are not representatives of the well-described genera Nitrosomonas and Nitrobacter but some other ammonia oxidisers from the beta subclass of Proteobacteria and a thus far unknown nitrite oxidising population.

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43

Rajbhandari, B. K., e A. P. Annachhatre. "Modeling response of nitrifying biofilm to inhibitory shock loads". Water Science and Technology 50, n. 6 (1 settembre 2004): 53–60. http://dx.doi.org/10.2166/wst.2004.0359.

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Abstract (sommario):

To study the response of nitrifying biofilm to inhibitory shock loads, a lab-scale nitrifying biofilm reactor was operated in ambient conditions. Shock loads of various concentrations of inhibitory compound were applied to the biofilm. Aniline was used as an inhibitory compound. The experimental results were utilized to develop a model for predicting the variation of effluent nitrate concentration from the biofilm reactor for given shock loads of aniline concentration and exposure time both in exposure as well as in recovery phase. Close agreement between model and experimental observation of bulk aniline concentration and effluent nitrate concentration was obtained which indicates the usefulness of the model to estimate bulk aniline concentration and to predict the response of inhibitory shock loads on nitrifying biofilm.

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44

Ginestet, Philippe, Jean-Marc Audic, Vincent Urbain e Jean-Claude Block. "Estimation of Nitrifying Bacterial Activities by Measuring Oxygen Uptake in the Presence of the Metabolic Inhibitors Allylthiourea and Azide". Applied and Environmental Microbiology 64, n. 6 (1 giugno 1998): 2266–68. http://dx.doi.org/10.1128/aem.64.6.2266-2268.1998.

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Abstract (sommario):

ABSTRACT The effects of two metabolic inhibitors on an enriched nitrifying biomass during incubation for short periods of time were investigated by determining respirometric measurements. Allylthiourea (86 μM) and azide (24 μM) were shown to be strong, selective inhibitors of ammonia and nitrite oxidation, respectively. Consequently, a differential respirometry method for estimating nitrifying and heterotrophic bacterial activities within a mixed biomass is proposed.

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45

Bourgeois, François-René, Frédéric Monette e Daniel G. Cyr. "Operational modifications for the development of nitrifying bacteria in a large-scale biological aerated filter and its impact on wastewater treatment". Water Science and Technology 78, n. 8 (25 ottobre 2018): 1704–14. http://dx.doi.org/10.2166/wst.2018.447.

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Abstract (sommario):

Abstract To develop a better understanding for fixed biomass processes, the development of a nitrifying bacterial biofilm, as well as the performance of treatment during modifications to operational conditions of a full-scale submerged biological filter were examined. The development of the nitrifying biofilm was investigated at four depth levels (1, 2, 4 and 5 feet). The result of bacterial subpopulations analyzed by qPCR relative to the physico-chemical parameters of the wastewater during the various tests (sustained aeration, modified backwash parameters and inflow restriction) revealed an increase of the relative presence of nitrifying microorganisms throughout the biofilm (especially for nitrite oxidizing bacteria (NOB)), but this was not necessarily accompanied by a better nitrification rate. The highest observed nitrification rate was 49% of removal in the test cell during backwashing conditions, whereas the relative ammonia oxidizing bacteria (AOB) population was 0.032% and NOB was 0.008% of the total biomass collected. The highest percentage of nitrifying bacteria observed (0.034% AOB and 0.18% NOB) resulted in a nitrification rate of 21%. The treatment of organic matter determined by measuring the chemical and biochemical oxygen demand (COD, CBOD5) was improved.

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46

Alfisah, R. K., I. Rusmana, T. Widiyanto e R. Affandi. "The Abundance and Potential Activity of Nitrifying, Denitrifying, and Nitrate-ammonifying Bacteria in the Vanamae Shrimp Culture in Karawang". IOP Conference Series: Earth and Environmental Science 1062, n. 1 (1 luglio 2022): 012011. http://dx.doi.org/10.1088/1755-1315/1062/1/012011.

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Abstract (sommario):

Abstract The existence of inorganic nitrogen in the shrimp pond ecosystem will not be separated from the nitrogen cycle and microbiological processes including the activity of microbes. This study aimed to analyze the abundance and potential rate of nitrifying, denitrifying, and nitrate-ammonifying bacteria in Vanamae shrimp cultivation. Water samples were collected on a shrimp pond in Karawang, West Java. Water sampling was carried out at the age of shrimp rearing 0 days, 21 days, 65 days, and 89 days. Water sampling was conducted at four points representing an area of the pond. The bacterial abundances were analyzed using Most Probable Number (MPN) method. The potential rates of bacteria were calculated by Michaelis-Menten kinetics. The highest abundance of nitrifying bacteria was 3.690 log cells ml-1 on 65 days, denitrifying bacteria was 3.415 log cells mL-1 on 89 days, and nitrate-ammonifying bacteria was 3.079 log cells mL-1 on 65 days of shrimp cultivation. The affinity of enzymes related to ammonia oxidation from nitrifying bacteria was higher than nitrate reduction from denitrifying and nitrate-ammonifying bacteria. Generally, nitrifying bacteria were the most abundant and dominant activity over shrimp cultivation.

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47

Yosmaniar, Y., T. Sumiati e M. Mulyasari. "Growth Performance and Survival Rate of Catfish (Pangasius sp) with the Application of the Nitrifying and Denitrifying Bacteria". IOP Conference Series: Earth and Environmental Science 934, n. 1 (1 novembre 2021): 012004. http://dx.doi.org/10.1088/1755-1315/934/1/012004.

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Abstract (sommario):

Abstract Nitrifying and denitrifying bacteria can be used as a bioremediation agents in aquaculture. The purpose of this experiment is to evaluate the optimal growth and survival performances of catfish rearing with the application of nitrifying and denitrifying bacteria. A completely randomized design was performed with the following treatments: A) nitrifying and denitrifying bacteria NP2-DP1; B) nitrifying and denitrifying bacteria NP2-DP2; C) commercial bacteria and D) without bacterial isolate (control), each with 3 replications. Twelve containers (34 x 34 x 45 cm) were used with a volume of 20 L equipped with aeration. The catfish used (Pangasius sp) has a body weight of 8.33 g ± 0.1 and stocking density of 20 fish / container reared within 30 days. Feed was applied to the fish at 3% of their body weight for three times a day at 08.00 am, 12.00 and 15.00 pm . . Inoculation of bacteria on day 10th and; 20th, that is 108 cfu / mL. The parameters measured were growth rate, survival rate, and water quality. Sampling was carried out every 10 days. The results showed that the application of NP2 and DP1 was the optimal to increase the growth and survival of catfish.

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48

Sirotkin, A. S., J. V. Kobeleva e E. S. Gorshkova. "Bio-Augmentation of Nitrifying Microorganisms to Increase the Efficiency of Oxidation of Nitrogen Compounds during Wastewater Biofiltration". Biotekhnologiya 36, n. 2 (2020): 99–107. http://dx.doi.org/10.21519/0234-2758-2020-36-2-99-107.

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Abstract (sommario):

The efficiency of nitrifying bacteria bio-augmentation into biofilm microbiocenosis during 30-day continuous biofiltration of municipal wastewater model solution has been assessed. The laboratory setup consisted of two parallel operating biofilters, in one of which, after start-up period, cultures of ammonium-oxidizing and nitrite-oxidizing bacteria of the Nitrobacter genus were sequentially introduced. It was established that the bio-augmentation of ammonium-oxidizing bacteria into the biofilm microbiocenosis led to an increase in the efficiency of ammonium nitrogen removal by an average of 1.6 times compared to the control biofilter. The subsequent bio-augmentation of nitrite-oxidizing bacteria caused an increase in the amount of nitrates in purified water by 2 times on average. As a result of bio-augmentation of nitrifying bacteria into the biofilm microbiocenosis, the nitrification process was intensified. Quantitative and qualitative identification of microorganisms via fluorescence in situ hybridization showed an increase in the number of nitrifying microorganisms in the biofilm of experimental biofilter, which confirms the efficiency of introduction of microorganisms and correlates with the data on biotransformation of nitrogen compounds. nitrifying microorganisms, wastewater biofiltration, biofilms, bio-augmentation, fluorescence in situ hybridization.

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49

Okabe, S., T. Kindaichi, Y. Nakamura e T. Ito. "Eco-physiology of autotrophic nitrifying biofilms". Water Science and Technology 52, n. 7 (1 ottobre 2005): 225–32. http://dx.doi.org/10.2166/wst.2005.0205.

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Abstract (sommario):

Microautoradiography combined with fluorescent in situ hybridization (MAR-FISH), a powerful tool for linking physiology with identification of individual cells, was applied to investigate microbial interactions between nitrifying bacteria and coexisting heterotrophic bacteria in an autotrophic nitrifying biofilm community fed with only ammonia as the sole energy source and bicarbonate as the sole carbon source. First, nitrifying bacteria were radiolabeled by culturing the biofilm samples with [14C]bicarbonate for 6 h, and then the transfer of radioactivity from nitrifying bacteria to heterotrophic bacteria was monitored by using MAR-FISH. MAR-FISH revealed that the heterotrophic bacterial community was composed of bacteria that were phylogenetically and metabolically diverse. We could obtain direct evidence that organic matter derived from nitrifiers was subsequently utilized by mainly filamentous bacteria belonging to the Chloroflexi (green non-sulfur bacteria) group or CFB group in the biofilm, which was clearly visualized by MAR-FISH at single cell resolution for the first time. On the other hand, the members of the α- and γ-Proteobacteria were specialized to utilize low-molecular-weight organic matter. This community represents functionally integrated units that assure maximum access to and utilization of metabolites of nitrifiers.

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50

Rodríguez Rodríguez, Abad, Silvia Mau Inchaustegui, Lilliana Piedra Castro, Ricardo Jiménez Montealegre e Juan Pablo Herrera Vargas. "Isolation of ammonium- and nitrite-oxidizing bacterial strains from soil, and their potential use in the reduction of nitrogen in household waste water". Revista de Biología Tropical 65, n. 4 (19 settembre 2017): 1527. http://dx.doi.org/10.15517/rbt.v65i4.26509.

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Abstract (sommario):

Currently, nitrogen has become the main element of water pollution, causing riverine, lacustrine and coastal eutrophication. The continuous contamination of aquifers and the absence of planned water resource utilization, boost its scarcity, and has been the only way in which our societies become aware of the urgent need to process the generated wastewater. The objective of this research was to evaluate the nitrifying capacity of different autochthonous bacterial isolates from soils from nearby sources of domestic wastewater drainage. For this, bacteria were isolated from Pirro River, contaminated with nitrogen of domestic sewage. Nitrifying bacteria were counted by serial dilution and agar plates, and were isolated until obtaining axenic colonies. These were identified by biochemical batteries or genetic sequencing, and the quantification of their nitrifying capacity was obtained by the methods 4500- NH4 + -F and 4500-NO-2-B, all between September 26, 2011 and March 16, 2014. A total of seven strains of nitrifying microorganisms were isolated and purified, including four Streptomyces sp., one Pseudomonas putida, one Sphingomonas sp. and one Aeromonas sp. We found that there were 2.23 x 105 UFC/g of soil of ammonium oxidizing bacteria and 2.2 x 104 CFU/g of soil of nitrite oxidizing bacteria in the samples. The quantification of the nitrifying capacity of the strains by colorimetric methods, determined that the maximum ammonium removal capacity was 0.050 mg N/L/day and 0.903 mg N/L/day of nitrite. The collection of few strains of nitrifying organisms and a low CFU count, can be attributed to the technique used, since this only recovers 1 % of the microorganisms present in a sample, which, however, is acceptable for studies which main purpose is to obtain cultivable microorganisms. Future research should consider removal tests with higher ammonium and nitrite levels, to find the maximum capacity of the isolated microorganisms, and evaluate their potential use in wastewater treatment systems.

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