Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| use of natural zeolite to enhance nitrification in biofilter. | to enhance nitrification, natural zeolite and activated carbon were tested as a media in a biofilter to treat wastewater containing relatively high concentrations of tkn. using those media, the adsorption isotherms for ammonium ion were compared; the k values for natural zeolite and activated carbon were found to be 0.5117 and 0.0006, respectively. in comparison of the performance of the two media, two identical, lab-scale biofilters were then operated for 4 months. the effect of nh3-n loading r ... | 2002 | 12164639 |
| go or no go for gel entrapped nitrifiers? a belgian case study. | in the coming years, as stricter environmental requirements are imposed, many european union wastewater treatment plants (wwtp) need to be expanded and/or upgraded. this requires considerable investments. optimising the renovation recourses can lead to significant savings. the use of entrapped nitrifying bacteria for upgrading of wwtp towards nutrient removal may be benificial. long term pilot tests were performed to evaluate a so-called pellet reactor. differences in performance and microbiolog ... | 2002 | 12216669 |
| melissa: a loop of interconnected bioreactors to develop life support in space. | the development of a loop of interconnected continuous bioreactors, aimed to provide life support in space, is reported. the complete loop concept consists of four bioreactors and one higher plant compartment. for its realization the continuous and controlled operation of the bioreactors is characterized, up to the pilot scale level, first for each individual reactor, second for the interconnected reactor operation. the results obtained with the two more advanced bioreactors in the micro ecologi ... | 2002 | 12385718 |
| ammonia- and nitrite-oxidizing bacterial communities in a pilot-scale chloraminated drinking water distribution system. | nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. the diversity of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using terminal restriction fragment length polymorphism (t-rflp) analysis and 16s rrna gene (ribosomal dna [rdna]) cloning and sequencing. for ammonia ... | 2002 | 11772611 |
| the aquatic budding bacterium blastobacter denitrificans is a nitrogen-fixing symbiont of aeschynomene indica. | blastobacter spp. are freshwater bacteria that form rosette structures by cellular attachment to a common base. comparative analyses of ribosomal 16s rrna gene and internally transcribed spacer region sequences indicated that b. denitrificans is a member of the alpha-subdivision of proteobacteria. among the alpha-proteobacteria, b. denitrificans was related to a cluster of genera, including rhodopseudomonas palustris, afipia felis, nitrobacter hamburgensis, and bradyrhizobium spp. although the p ... | 2002 | 11872460 |
| in situ characterization of nitrifiers in an activated sludge plant: detection of nitrobacter spp. | the purpose of this work was to investigate microbial ecology of nitrifiers at the genus level in a typical full-scale activated sludge plant. | 2002 | 12174041 |
| competition between two nitrite-oxidizing bacterial populations: a model for studying the impact of wastewater treatment plant discharge on nitrification in sediment. | abstract nitrobacter, a ubiquitous nitrite oxidizer in natural and anthropized environments, is commonly studied as the model genus performing the second stage of nitrification. in rivers, wastewater treatment plant discharges may affect the nitrite-oxidizing activity and the responsible genera that are largely associated with sediment. we used a laboratory batch culture approach with nitrobacter wynogradskyi ssp. agilis strain ag and nitrobacter hamburgensis strain x(14) to characterize the pos ... | 2002 | 19709262 |
| application of temperature gradient gel electrophoresis to the characterization of a nitrifying bioaugmentation product. | the microbial population of a nitrifying bioaugmentation product (nbp) has been examined using a combination of conventional bacteriological methods and modern molecular techniques. variable region 3 (v3) of the 16s rrna genes of the bacteria in nbp was amplified via the polymerase chain reaction (pcr) with universal eubacterial primers and analyzed via temperature gradient gel electrophoresis (tgge). two of the predominant pcr products in nbp were purified from the tgge gel matrix, reamplified ... | 2003 | 19719689 |
| biological treatment process of air loaded with an ammonia and hydrogen sulfide mixture. | the physico-chemical characteristics of granulated sludge lead us to develop its use as a packing material in air biofiltration. then, the aim of this study is to investigate the potential of unit systems packed with this support in terms of ammonia and hydrogen sulfide emissions treatment. two laboratory scale pilot biofilters were used. a volumetric load of 680 g h2s m(-3) empty bed day(-1) and 85 g nh3 m(-3) empty bed day(-1) was applied for eight weeks to a unit called bgsn (column packed wi ... | 2003 | 12656240 |
| canon and anammox in a gas-lift reactor. | anoxic ammonium oxidation (anammox) and completely autotrophic nitrogen removal over nitrite (canon) are new and promising microbial processes to remove ammonia from wastewaters characterized by a low content of organic materials. these two processes were investigated on their feasibility and performance in a gas-lift reactor. the anammox as well as the canon process could be maintained easily in a gas-lift reactor, and very high n-conversion rates were achieved. an n-removal rate of 8.9 kg n (m ... | 2003 | 12586414 |
| diversity of nitrifying bacteria in full-scale chloraminated distribution systems. | chloramination for secondary disinfection of drinking water often promotes the growth of nitrifying bacteria in the distribution system due to the ammonia introduced by chloramine formation and decay. this study involved the application of molecular biology techniques to explore the types of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) present in several full-scale chloraminated systems. the results of aob community characterization indicated the ubiquitous detection of ... | 2003 | 12465801 |
| use of polyclonal antibodies to detect and quantify the nor protein of nitrite oxidizers in complex environments. | in the approaches or models which aim to understand and/or predict how the functioning of ecosystems may be affected by perturbations or disturbances, little attention is generally given to microorganisms. even when they are taken into account as indicators, variables which are poorly informative about the changes in the microbial functioning (microbial biomass or diversity or total number of microorganisms) are often used. to be able to estimate, in complex environments, the quantity of enzymes ... | 2003 | 12609727 |
| susceptibility of ammonia-oxidizing bacteria to nitrification inhibitors. | activity of nitrification inhibitors to several typical ammonia-oxidizing bacteria isolated recently, i. e. nitrosococcus, nitrosolobus, nitrosomonas, nitrosospira and nitrosovibrio species was assayed using 2-amino-4-methyl-trichloromethyl-1,3,5-triazine (mast), 2-amino-4-tribromomethyl-6-trichloromethyl-1,3,5-triazine (br-mast), 2-chloro-6-trichloromethylpyridine (nitrapyrin) and others, and compared to confirm the adequate control of ammonia-oxidizing bacteria by the inhibitors. the order of ... | 2003 | 12710742 |
| changing concepts in the systematics of bacterial nitrogen-fixing legume symbionts. | as of february 2003, bacteria that form nitrogen-fixing symbiotic associations with legumes have been confirmed in 44 species of 12 genera. phylogenies of these taxa containing legume symbionts based on the comparative analysis of 16s rdna sequences show that they are not clustered in one lineage but are distributed in the classes alphaproteobacteria and betaproteobacteria, and dispersed over the following nine monophyletic groups, being intermingled with other taxa that do not contain legume sy ... | 2003 | 12949698 |
| structure and activity of multiple nitrifying bacterial populations co-existing in a biofilm. | a biofilm from a nitrifying pilot-scale sequencing batch reactor was investigated for effects of varying process conditions on its microscale activity and structure. microsensor measurements of oxygen, substrates and products of nitrification were applied under incubation at different ammonium and oxygen concentrations which reflected various situations during a treatment cycle. a high net n loss was observed under high ammonium (ha) concentrations in contrast to low ones. additionally, results ... | 2003 | 12713462 |
| dynamic response of nitrifying activated sludge batch culture to increased chloride concentration. | dynamic response of nitrifying activated sludge batch cultures to increased chloride concentration was studied in this paper, which focused upon the changes in the specific nitrification rate (snr) and nitrifier population when the chloride level was gradually or stepwise increased to 30,000 mg cl l-1. the dominant species of ammonia-oxidizers and nitriteoxidizers in the population were examined by fluorescent in situ hybridization technique with 16s rrna-targeted oligonucleotide probes. it was ... | 2003 | 14509699 |
| molecular analysis of microbial communities in nitrification and denitrification reactors treating high ammonia leachate. | molecular analysis of microbial populations in two bench-scale nitrification and denitrification reactors fed with high ammonia landfill leachate was conducted in this study by using dgge, cloning, and fish techniques in addition to classical efficiency control parameters. nitrification tank was operated with a computer-controlled alkalinity dosing system to supply the alkalinity intermittently as consumed on the basis of on-line ph monitoring. by keeping the ph at 7.0 with this system, 99% nitr ... | 2003 | 14524656 |
| nitrification and nitrifying bacteria in the lower seine river and estuary (france). | the achères wastewater treatment plant, located just downstream of paris, discharges its effluents into the lower seine river. the effluents contain large numbers of heterotrophic bacteria, organic matter, and ammonium and are a source of nitrifying bacteria. as a result, degradation of organic matter by heterotrophic bacteria and subsequent oxygen depletion occur immediately downstream of the effluent outlet, whereas nitrifying bacteria apparently need to build up a significant biomass before a ... | 2003 | 14660353 |
| nitrite accumulation followed by denitrification using sequencing batch reactor. | biological ammonia-nitrogen removal utilizes two distinct processes, nitrification and denitrification. in nitrification, ammonia oxidizes to nitrite then to nitrate. in this study, elimination of nitrite oxidation to nitrate step was attempted in order to directly remove nitrite to nitrogen gas by denitrification. for this study the supernatant from an anaerobic digester was used as an ammonia source and a sequencing batch reactor (sbr) was employed. emphasis was given to the evaluation of the ... | 2004 | 15137406 |
| effects of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as end product. | the effect of seawater salinity on nitrite accumulation in short-range nitrification to nitrite as the end product was studied by using a sbr. experimental results indicated that the growth of nitrobacteria was inhibited and very high levels of nitrite accumulation at different salinities were achieved under the conditions of 25-28 degrees c, ph 7.5-8.0, and the influent ammonia nitrogen of 40-70 mg/l when seawater flow used to flush toilet was less than 35% (salinity 12393 mg/l, cl- 6778 mg/l) ... | 2004 | 15137648 |
| influence of chemical oxygen demand/total kjeldahl nitrogen ratio and sludge age on nitrification of nitrogenous wastewater. | four laboratory-scale biological nitrification units (influent total kjeldahl nitrogen [tkn] = 1002 to 1062 mg/l) were operated at chemical oxygen demand (cod)/tkn ratios of approximately 0.5, 1.0,15, and 2.0 and at three different sludge ages of 30, 20, and 10 days to study the influence of cod/tkn, sludge age, cod loading, and tkn loading on nitrification and nitrifiers. percent nitrification was found to increase with decreases in cod/tkn and increases in sludge age. the average nitrifier con ... | 2004 | 15168847 |
| dynamics of a pasture soil microbial community after deposition of cattle urine amended with [13c]urea. | within grazed pastures, urine patches are hot spots of nitrogen turnover, since dietary n surpluses are excreted mainly as urea in the urine. this short-term experiment investigated 13c uptake in microbial lipids after simulated deposition of cattle urine at 10.0 and 17.1 g of urea c m(-2). confined field plots without or with cattle urine amendment were sampled after 4 and 14 days, and soil from 0- to 5-cm and 10- to 20-cm depths was analyzed for content and composition of phospholipid fatty ac ... | 2004 | 15528493 |
| treatment of nitrogen and phosphorus in highly concentrated effluent in sbr and sbbr processes. | various sludge treatment processes produced supernatant with high ammonia concentration from 500 to 2,000 mgn/l and generally high phosphate concentration. conversion of ammonia into nitrite via partial nitrification has proven to be an economic way, reducing oxygen and external cod requirements during the nitrification/denitrification process. two processes with biomass retention are studied simultaneously: the sequencing batch reactor (sbr) and the sequencing batch biofilm reactor (sbbr). at a ... | 2004 | 15537016 |
| influence of long-term diesel fuel pollution on nitrite-oxidising activity and population size of nitrobacter spp in soil. | previous investigations have shown that ammonia oxidation is not inhibited by diesel fuel in a soil with a long history of contamination contrary to a non-contaminated soil. as a consequence, ammonia oxidation does not constitute a limited step in nitrification process (appl. environ. microbiol. 65 (1999) 4008). moreover, this type of soil also has had the opportunity to develop an abundant microbial population able to metabolise the diesel hydrocarbons. whether the properties of soil with a lon ... | 2004 | 15646378 |
| diversity of green-like and red-like ribulose-1,5-bisphosphate carboxylase/oxygenase large-subunit genes (cbbl) in differently managed agricultural soils. | a pcr-based approach was developed to detect ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) form i large-subunit genes (cbbl) as a functional marker of autotrophic bacteria that fix carbon dioxide via the calvin-benson-bassham cycle. we constructed two different primer sets, targeting the green-like and red-like phylogenetic groups of cbbl genes. the diversity of these cbbl genes was analyzed by the use of three differently managed agricultural soils from a long-term field experiment. ... | 2005 | 15640185 |
| [stability of shortcut nitrification-denitrification]. | the effects of temperature and aeration time on the stability of shortcut nitrification-denitrification are studied specially in some experiments are carried on a sequencing batch reactor (sbr) fed with soybean wastewater. results show that shortcut nitrification-denitrification achieved by controlling temperature was not stable until the temperature was more than 28 degrees c. in addition, for the first time strong effect of excess aeration on shortcut nitrification-denitrification is observed. ... | 2005 | 15859410 |
| [nitrification and denitrification in the integrated vertical flow constructed wetlands]. | nitrification and denitrification in the different layers of the integrated vertical flow constructed wetlands (ivcw) are studied. the results show the constants rate of nitrification and denitrification in the strata of ivcw were 0.01 - 6.35microg x (gxd)-1 and 3.37 - 4.19microg x (gxd)-1 respectively. the most probable number (mpn) method are employed to determine the number and distribution of nitrifying and denitrifying bacteria in the strata of the system. the results show that the numbers ... | 2005 | 15859407 |
| modeling microbial-mediated reduction in batch reactors. | the governing equations that depict microbially-mediated reduction of heavy metals in the subsurface include a system of coupled nonlinear partial differential equations (pde's) that describe physical (transport), chemical (sorption), and microbial (reduction/oxidation) processes. the existence of nonlinear reaction terms makes numerical simulations more challenging; however, with the advent of time-splitting solution algorithms, nonlinear reaction terms can be isolated from the convective-dispe ... | 2005 | 15833496 |
| dna microarray detection of nitrifying bacterial 16s rrna in wastewater treatment plant samples. | a small scale dna microarray containing a set of oligonucleotide probes targeting the 16s rrnas of several groups of nitrifying bacteria was developed for the monitoring of wastewater treatment plant samples. the microarray was tested using reference rrnas from pure cultures of nitrifying bacteria. characterization of samples collected from an industrial wastewater treatment facility demonstrated that nitrifying bacteria could be detected directly by microarray hybridization without the need for ... | 2005 | 16009395 |
| [potential of nitrification and denitrification in water purification system with hydroponic bio-filter method]. | the potential of nitrification and denitrification of sediment and the density of ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in sediment in water quality purifying system with hydroponic bio-filter method (hbfm) were measured. the variation of nitrification and denitrification potential of the sediment along the stream way was quantitatively studied. the results show that among the sediments from front, middle and retral part of the stream way, the sediment from middle part reach ... | 2005 | 16004307 |
| calcium carbonate phosphate binding ion exchange filtration and accelerated denitrification improve public health standards and combat eutrophication in aquatic ecosystems. | cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. the process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. especially in madrona marsh, one of the last remaining vernal marshes in the greate ... | 2005 | 16381147 |
| pilot-scale studies on biological treatment of hypersaline wastewater at low temperature. | in order to investigate the feasibility of biological treatment of hypersaline wastewater produced from toilet flushing with seawater at low temperature, pilot-scale studies were established with plug-flow activated sludge process at low temperature (5-9 degrees c) based on bench-scale experiments. the critical salinity concentration of 30 g/l, which resulted from the cooperation results of the non-halophilic bacteria and the halophilic bacteria, was drawn in bench-scale experiments. pilot-scale ... | 2005 | 16459784 |
| effects of aeration cycles on nitrifying bacterial populations and nitrogen removal in intermittently aerated reactors. | the effects of the lengths of aeration and nonaeration periods on nitrogen removal and the nitrifying bacterial community structure were assessed in intermittently aerated (ia) reactors treating digested swine wastewater. five ia reactors were operated in parallel with different aeration-to-nonaeration time ratios (ana). populations of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) were monitored using 16s rrna slot blot hybridizations. aob species diversity was assessed u ... | 2005 | 16332848 |
| high levels of nitrifying bacteria in intermittently aerated reactors treating high ammonia wastewater. | changes in the fractions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in two laboratory-scale reactors were investigated using 16s rrna probe hybridizations. the reactors were operated in intermittent aeration mode and different aeration cycles to treat anaerobically digested swine wastewater with ammonia concentrations up to 175 mg nh(3)-n/l. high ammonia removals (>98.8%) were achieved even with increased nitrogen loads and lower aeration: non-aeration time ratios of 1h:3h. nit ... | 2005 | 16332337 |
| chemolithotrophic haloalkaliphiles from soda lakes. | this paper summarizes recent data on the occurrence and properties of lithotrophic prokaryotes found in extremely alkaline, saline (soda) lakes. among the chemolithotrophs found in these lakes the obligately autotrophic sulfur-oxidizing bacteria were the dominant, most diverse group, best adapted to haloalkaline conditions. the culturable forms are represented by three new genera, thioalkalimicrobium, thioalkalivibrio and thioalkalispira in the gammaproteobacteria. among them, the genus thioalka ... | 2005 | 16329914 |
| nitrobacter and nitrospira genera as representatives of nitrite-oxidizing bacteria: detection, quantification and growth along the lower seine river (france). | pollution from agriculture and urban effluents influences the ecology and biochemical functioning of the seine river. nitrification dominates nitrogen transformations downstream of the effluents of the paris wastewater treatment plant (wwtp) at achères, treating, by activated sludge the wastewater of 6.5 million inhabitant equivalents from paris and its suburbs, without nitrification and denitrification treatment. it discharges effluents containing large amounts of nitrogen, ammonium mostly (app ... | 2005 | 16303163 |
| using a compact combined constructed wetland system to treat agricultural wastewater with high nitrogen. | the objectives of this study were to find appropriate conditions for nitrogen removal by a compact combined constructed wetland system and to evaluate the removal rate constant in a tropical climate. this study will present suitable operating conditions for a combined system to treat pig farm wastewater containing high ammonia-nitrogen. four laboratory-scale combined constructed wetland units (0.5 x 1.0 x 1.0 m3): vertical flow vegetated bed over horizontal flow sand bed, were operated under an ... | 2005 | 16042242 |
| para-chlorophenol inhibition on cod, nitrogen and phosphate removal from synthetic wastewater in a sequencing batch reactor. | cod, nitrogen, phosphate and para-chlorophenol (4-chlorophenol, 4-cp) removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (sbr) at different sludge ages and initial para-chlorophenol (4-cp) concentrations. the nutrient removal process consisted of anaerobic, oxic, anoxic and oxic phases with hydraulic residence times (hrt) of 1/3/1/1 h and a settling phase of 0.75 h. a box-wilson statistical experiment design was used considering the sludge age (5-25 day ... | 2005 | 16023572 |
| [operation performance of membrane nitrification bioreactor for ammonia-containing wastewater]. | the operation performance of membrane nitrification bioreactor to treat ammonia-containing wastewater as well as the capabilities of separation and filtration of polypropylene membrane modules were tested. the removal efficiency of ammonia was kept higher than 95% when the hydraulic retention time was set at 1 day, the influent concentration was increased up to 80 mmol (nh4+ -n) x l(-1) and the volume loading rate was increased up to 1.12 kg (nh4+ -n) x m(-3) x d(-1). the biomass in the reactor ... | 2005 | 16013490 |
| improvement of nano2-oxidizing activity in nitrobacter vulgaris by coentrapment in polyacrylamide containing polydimethylsiloxane copolymer and deae-sephadex. | removal of nitrite and nitrate from drinking water has attracted great attention in recent years because of the human health risk induced by the exposure to contaminated groundwater and surface water. we have therefore tested a model nitrite oxidation system by coentrapping the nano2 oxidizer nitrobacter vulgaris with polydimethylsiloxane (pdms) copolymer and deae-sephadex in a polyacrylamide gel. the copolymer and the anion exchanger facilitate the diffusion of oxygen and nano2, respectively, i ... | 2005 | 16204501 |
| influence of inorganic nitrogen management regime on the diversity of nitrite-oxidizing bacteria in agricultural grassland soils. | to assess links between the diversity of nitrite-oxidizing bacteria (nob) in agricultural grassland soils and inorganic n fertilizer management, nob communities in fertilized and unfertilized soils were characterized by analysis of clone libraries and denaturing gradient gel electrophoresis (dgge) of 16s rrna gene fragments. previously uncharacterized nitrospira-like sequences were isolated from both long-term-fertilized and unfertilized soils, but dgge migration patterns indicated the presence ... | 2005 | 16332819 |
| validation of the correct start codon of norx/nxrx and universality of the noraxb/nxraxb gene cluster in nitrobacter species. | the complete norx/nxrx sequence of five nitrobacter strains was determined showing that the noraxb/nxraxb gene cluster is present in all hitherto described nitrobacter species. evidence is provided that the previously published sequence of norx in n. hamburgensis x14(t) contains an invalid base "insertion," which resulted in a frameshift and a misidentified start codon. | 2006 | 16874545 |
| [nitrification and denitrification in bacf for treating high ammonia source water]. | a high ammonia micropolluted source water advanced treatment for ammonia removal by biological activated carbon filter was tested. the removal rate of ammonia was high than 95% when influent concentration was under 1.0 mg/l. the removal rate decreased with the influent concentration increased when the ammonia concentration was in range of 1.5 - 4.9 mg/l and the influent do was under 10 mg/l, and the minimum removal rate was about 30%. the key factor of restrict nitrification in bacf was the infl ... | 2006 | 16599123 |
| stoichiometric and kinetic characterisation of nitrobacter in mixed culture by decoupling the growth and energy generation processes. | the growth, maintenance and lysis processes of nitrobacter were characterised. a nitrobacter culture was enriched in a sequencing batch reactor (sbr). fluorescent in situ hybridisation showed that nitrobacter constituted 73% of the bacterial population. batch tests were carried out to measure the oxygen uptake rate and/or nitrite consumption rate when both nitrite and co2 were in excess, and in the absence of either of these two substrates. the results obtained, along with the sbr performance da ... | 2006 | 16673416 |
| [isolation and characterization of heterotrophic nitrifying bacteria]. | method of isolating the heterotrophic nitrifiers and the characterization of the heterotrophic nitrification were studied. two heterotrophic nitrifiers were newly isolated from a membrane bioreactor (mbr) in which the tn removal efficiency was 80.1%. the batch test results indicate that bacillus sp. ly and brevibacillus sp. ly could utilize the organic carbon as the source of assimilation when they grew on glucose and ammonium chloride medium companying the formation of oxidized-nitrogen. after ... | 2006 | 16686198 |
| research on leachate recirculation from different types of landfills. | landfills can produce a great amount of leachate containing highly concentrated organic matter. this is especially true for the initial leachate from landfilled municipal solid wastes (msw) that generally has concentrations of cod(cr) and bod(5) up to 80,000 and 50,000mg/l, respectively. the leachate could be disposed by means of recirculating technique, which decomposes the organics through the action of proliferating microorganisms and thereby purifies the leachate, and simultaneously accelera ... | 2006 | 16321514 |
| nitrification performance and microbial community dynamics in a submerged membrane bioreactor with complete sludge retention. | a submerged membrane bioreactor (mbr) supplied with inorganic ammonium-bearing wastewater (nh(4)(+)-n, 500 mgl(-1)) was operated for 260 days without sludge purge under decreased hydraulic retention times (hrt) through six steps (from 30 to 5h). almost complete nitrification was obtained at a volumetric loading rate (vlr)1.2g nh(4)(+)-nl(-1)day(-1). the sludge nitrification activities were evaluated at each stage. the specific ammonium oxidizing rate (saor) decreased from the initial 0.45 to 0.1 ... | 2006 | 16310272 |
| genome sequence of the chemolithoautotrophic nitrite-oxidizing bacterium nitrobacter winogradskyi nb-255. | the alphaproteobacterium nitrobacter winogradskyi (atcc 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. there were extensive similarities to genes in two alphaproteobacteria, bradyrhizobium japonicum usda110 (1,300 genes) and rhodopseudomonas palustris cga009 cg (815 genes). genes encoding p ... | 2006 | 16517654 |
| long term effects of salt on activity, population structure and floc characteristics in enriched bacterial cultures of nitrifiers. | the effect of salinity on the activity, the composition of nitrifiers and floc characteristics of nitrifying sludge was studied. non-adapted and adapted (to 10g nacl-cl(-)/l for one year) enriched cultures of nitrifiers were tested in three sequencing batch reactors. salt was increased gradually with 5 up to 40 g cl(-)/l. no difference in steady state activity was observed between the adapted and non-adapted sludge. the activities of ammonia and nitrite oxidizers dropped 36% and 11%, respectivel ... | 2006 | 16530803 |
| the inhibitory effects of free nitrous acid on the energy generation and growth processes of an enriched nitrobacter culture. | the inhibitory effects of nitrite (no2-)/free nitrous acid (hno2-fna) on the metabolism of nitrobacter were investigated using a method allowing the decoupling of the growth and energy generation processes. a lab-scale sequencing batch reactor was operated forthe enrichment of a nitrobacter culture. fluorescent in situ hybridization (fish) analysis showed that 73% of the bacterial population was nitrobacter. batch tests were carried out to assess the oxygen and nitrite consumption rates of the e ... | 2006 | 16903283 |
| effect of nitrite concentration on the distribution and competition of nitrite-oxidizing bacteria in nitratation reactor systems and their kinetic characteristics. | genus nitrospira and nitrobacter species are the key nitrite-oxidizing bacteria (nob) in nitrifying wastewater treatment plants. it has been hypothesized that genus nitrospira are k-strategists and can exploit low amounts of nitrite more efficiently than nitrobacter. in contrast, nitrobacter species are r-strategists that can grow faster than nitrospira. to elucidate the k/r hypothesis and to analyze the effect of substrate (nitrite) concentration on the competition and distribution of the two n ... | 2006 | 16460781 |
| selective enrichment and molecular characterization of a previously uncultured nitrospira-like bacterium from activated sludge. | previously uncultured nitrite-oxidizing bacteria affiliated to the genus nitrospira have for the first time been successfully enriched from activated sludge from a municipal wastewater treatment plant. during the enrichment procedure, the abundance of the nitrospira-like bacteria increased to approximately 86% of the total bacterial population. this high degree of purification was achieved by a novel enrichment protocol, which exploits physiological features of nitrospira-like bacteria and inclu ... | 2006 | 16478447 |
| simulation modeling for nitrogen removal and experimental estimation of mass fractions of microbial groups in single-sludge system. | nitrification-denitrification in a single-sludge nitrogen removal system (ssnrs; with a sufficient carbon source for denitrification) was performed. with an increase in the mixed liquor recycle ratio (r(m)) from 1 to 2, the total nitrogen (tn) removal efficiency at a lower volumetric loading rate (vlr=0.21 nh(4)(+)-n m(-3) d(-1)) increased, but the tn removal efficiency at a higher vlr (0.35 kg nh(4)(+)-n m(-3) d(-1)) decreased. a kinetic model that accounts for the mass fractions of nitrosomona ... | 2006 | 15936800 |
| effect of temperature and free ammonia on nitrification and nitrite accumulation in landfill leachate and analysis of its nitrifying bacterial community by fish. | the cause of seasonal failure of a nitrifying municipal landfill leachate treatment plant utilizing a fixed biofilm was investigated by wastewater analyses and batch respirometric tests at every treatment stage. nitrification of the leachate treatment plant was severely affected by the seasonal temperature variation. high free ammonia (nh3-n) inhibited not only nitrite oxidizing bacteria (nob) but also ammonia oxidizing bacteria (aob). in addition, high ph also increased free ammonia concentrati ... | 2006 | 15927463 |
| achieving biological nitrogen removal via nitrite by salt inhibition. | the principal aim of this paper is to develop and evaluate an approach to obtain nitrogen removal bypassing nitrate. the method is based on the addition of sodium chloride (naci), selective inhibitor of nitrite oxidizers, to influent. validation of the new method was conducted on laboratory-scale experiments applying the sbr activated sludge process to domestic wastewater with low c/n ratio. with the aerobic-anoxic sequence, three parallel sbrs achieving complete nitrification-denitrification ar ... | 2006 | 16749447 |
| [community structure of nitrification bacteria in aerobic short-cut nitrification granule]. | by using a lab-scale aerated upflow sludge bed reactor, the inoculated anaerobic granule was cultivated to aerobic nitrification granule, and then converted to short-cut nitrification granule with the short-cut nitrification efficiencies above 90%. appling real-time quantity pcr, and florescent in situ hybridization techniques, the ecological community structure of nitrification bacteria in aerobic granules were studied. the results show that there existed a layered structure in the aerobic gran ... | 2006 | 17117645 |
| [effects of hydraulic retention time (hrt) on nitrification performance and microbial community of conventional activated sludge (cas)]. | a conventional activated sludge system was used to treat the ammonium-bearing inorganic wastewater for 260 days under decreased hrts. when treating 500 mg x l(-1) nh4+ -n wastewater, over 98% ammonia removal could be obtained at hrt > or =20 h. sharp washout of biomass occurred when hrt was further decreased, resulting in the accumulation of ammonium and nitrite. changes in the community structure were monitored by microbial quinone and conventional analytical methods. quinone profiles indicated ... | 2006 | 17117646 |
| [effect of osmotic pressure on nitrification]. | the effect of osmotic pressure on nitrification was investigated in the internal-loop air-lift nitrifying reactor. when influent ammonia concentration is kept at 420mg x l(-1) and influent osmotic pressure is increased from 4.3 to 18.8 x 10(5) pa, the ammonia conversion of the nitrifying bioreactor is maintained between 93% and 100%. after influent osmotic pressure is further increased to 19.2 x 10(5)pa, the ammonia conversion goes down to 69.2%. the influence of osmotic pressure on nitrificatio ... | 2006 | 16572857 |
| development and calibration of a nitrification pde model based on experimental data issued from biofilter treating drinking water. | to remove ammonia for production of drinking water, nitrification can be performed in a bio-filter. at least 1 month is necessary to capture from the groundwater and then grow a sufficient amount of nitrifying bacteria to reach the desired removal efficiency. improving start-up of bio-filters at low substrate concentration is therefore a major challenge. in this connection, it is important to develop appropriate models for designing, monitoring or analysing biofilm systems during start-up or fol ... | 2006 | 16598794 |
| competition between nitrospira spp. and nitrobacter spp. in nitrite-oxidizing bioreactors. | in this work the question was addressed if in nitrite-oxidizing activated sludge systems the environmental competition between nitrobacter spp. and nitrospira spp., which only recently has been discovered to play a role in these systems, is affected by the nitrite concentrations. two parallel chemostats were inoculated with nitrifying-activated sludge containing nitrospira and operated under identical conditions. after addition of nitrobacter to both chemostats, the nitrite concentration in the ... | 2006 | 16703620 |
| impact of prehybridization pcr amplification on microarray detection of nitrifying bacteria in wastewater treatment plant samples. | a gel-based microarray that included a set of 26 oligonucleotide probes targeting all nitrifying bacteria at varying levels of specificity suggested the presence of targeted microorganisms when hybridized to rna isolated from a wastewater treatment plant, but could not discriminate between perfectly matched and mismatched sequences due in part to low signal intensity. to enhance sensitivity and improve discrimination, polymerase chain reaction was used to selectively amplify the 16s rrna genes o ... | 2006 | 16913917 |
| post-treatment of a slaughterhouse wastewater: stability of the microbial community of a sequencing batch reactor operated under oxygen limited conditions. | slaughterhouse wastewater is a complex effluent with an important content of organic nitrogen. after an anaerobic treatment where most of the organic matter is removed, the nitrogen, remains as ammonium and post-treatment of the effluent is necessary. sequencing batch reactor (sbr) technology has been developed to completely remove nitrogen in one single reactor combining aerobic and anoxic stages. under oxygen limited conditions only nitrite is produced with concomitant energy saving. the stabi ... | 2006 | 16939105 |
| [start-up experiment on nitrification of mid-low ammonia concentration wastewater in sbr biofilm reactor]. | the start-up experiment on nitrification of mid-low nh4+ -n concentration wastewater was carried out in four sbr biofilm reactors for the establishment of completely autotrophic nitrogen removal process by the control of do and hrt and different medias. the results show that on the conditions of temperature 30 degrees c +/-2 degrees c, ammonia concentration 60-120 mg/l, do 0.8 - 1.0 mg/l and hydraulic retention time 24 h, the inoculating general active aerobic sludge and anaerobic sludge was nit ... | 2006 | 16767988 |
| structure of halothiobacillus neapolitanus carboxysomes by cryo-electron tomography. | carboxysomes are polyhedral bodies consisting of a proteinaceous shell filled with ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco). they are found in the cytoplasm of all cyanobacteria and some chemoautotrophic bacteria. previous studies of halothiobacillus neapolitanus and nitrobacter agilis carboxysomes suggest that the structures are either icosahedral or dodecahedral. to determine the protein shell structure more definitively, purified h. neapolitanus carboxysomes were re-examined ... | 2006 | 17028023 |
| [short-cut/complete nitrification and denitrification in a pilot-scale plant treating actual domestic wastewater]. | it is realized short-cut nitrification and denitrification in an a/o pilot-scale plant treating actual domestic wastewater controlling do concentration (0.5 mg/l) in low level at normal temperature, the average nitrite accumulation rate reached 85 % or above. three operational modes: low do short-cut nitrification and denitrification (mode 1), low do complete nitrification and denitrification (mode 2) and high do complete nitrification and denitrification (mode 3) were briefly compared, based on ... | 2006 | 17304844 |
| [spatial distribution of nitrifying bacteria communities in suspended carrier biofilm]. | spatial distributions of ammonia oxidizing bacteria (aob) and nitrobacteria in a renovated suspended carrier biofilm reactor (scbr) were investigated by using fluorescence in situ hybridization (fish) with 16s rrna oligonucleotide probes in combination with confocal laser scanning microscopy (clsm). three bench-scale structurally identical scbr reactors were operated under different ratios of cod to nh4(+) -n in influents, 5, 10 and 15, respectively. each scbr reactor was consisted of a 6 l of a ... | 2006 | 17328142 |
| [study of ammonium-nitrogen removal in suspended carrier biofilm reactor]. | in order to improve the ammonium-nitrogen (nh4+ -n) biodegradation rate, a suspended carrier was exploited and biofilm was cultivated in three different phases in a sequencing batch reactor (sbr). a flimsy honeycomb-shape biofilm was formed between the endocentric columns on the suspended carrier,which increased the cling amount of nitrobacteria and provided the better condition for nitrobacteria. the bioreactor was operated at the temperature ranges of 24-29 degrees c and ph between 7.8 and 8.2 ... | 2006 | 17304848 |
| [effect of denitrifying biofilm development on the surface configuration and chemical composition of pbs polymer]. | pbs, a new kind of biodegradable polymers (bdps), can be used as carbon source and biofilm carrier to remove nitrate from drinking water source. the effect of denitrification on the surface configuration and chemical composition of pbs was analyzed by using ir spectrum and sem observation. the results showed that pbs could be only decomposed under attack of microbial enzymes and provided the carbon source for biomass. influent nitrate concentration (53 mg x l- 1) can be reduced to less than 10 m ... | 2006 | 17304849 |
| [growth of heterotrophic bacteria and variation of related parameters in water distribution system in shanghai]. | the growth of heterotrophic bacteria and the variation of some physical chemical parameters were studied in a full-scale water distribution system in shanghai. the results showed that, in the water distribution system in shanghai, heterotrophic bacteria fed on organics were the major population in pipe water. with the water supply distance extending, bdoc in water increased and correspondingly both the number of heterotrophic bacteria and turbidity increased. in addition, the changes of differen ... | 2006 | 17326454 |
| [feasibility of treatment of micro-pollutant water polluted by nitrobenzene with ibac-process]. | the performance and feasibility of immobilization biological activated carbon (ibac) were investigated to treat micro-pollutant water containing nitrobenzene. ibac has been developed on the granular activated carbon by immobilization of selected and acclimated species of engineering bacteria to treat the micro-pollutant water containing nitrobenzene. the ibac removal efficiencies for nitrobenzene, permanganate index, turbidity, uv, ammonia and nitrite were compared with granular activated carbon ... | 2007 | 17891957 |
| [complete nitritation process in an biofilm moving bed system by controlling ph]. | complete nitritation process in an biofilm moving bed system was started-up by inoculating nitrobacteria and controlling ph, and the effects of nitrogen loading rate (nlr) and hydraulic retention time (hrt) on the stability of the system were investigated. the results showed that the system could achieve complete nitritation after 10 day's acclimation by controlling ph within the range of 7.7 - 8.2, under the conditions of temperature (30 +/- 1) degrees c, do 1.5 - 2.0 mg/l, hrt 24 h,ammonia con ... | 2007 | 17926400 |
| treatment efficiency and stoichiometry of a high-strength graywater. | the transit mission wastewater may represent a future graywater, in which toilet waste is separated from other household waste streams, and dilution water is minimal. a loading rate study indicated that denitrification is stoichiometrically limited, and nitrification was kinetically limited. denitrification stoichiometry was developed by deriving hypothetical molecular formulas of organic carbon inputs to be represented by the relative proportions of carbon, hydrogen, oxygen, and nitrogen. the d ... | 2007 | 18198701 |
| free ammonia and free nitrous acid inhibition on the anabolic and catabolic processes of nitrosomonas and nitrobacter. | the inhibitory effects of free ammonia (fa) and free nitrous acid (fna) on the catabolic and anabolic processes of nitrosomonas and nitrobacter were investigated using a method that allows decoupling the growth and energy generation processes. lab-scale sequencing batch reactors (sbrs) were operated for the enrichment of nitrosomonas and nitrobacter. fluorescent in-situ hybridization (fish) analysis showed that the reactors were 82% and 73% enriched with nitrosomonas and nitrobacter, respectivel ... | 2007 | 17951872 |
| [aerobic nitrifying granulation fed with source-separated urine in sequencing batch reactor]. | morphological characteristics of aerobic nitrifying granules that were utilized to treat the diluted source-separated urine were investigated in two lab-scale sequencing batch reactors. in the first sequencing batch reactor, which was inoculated with nitrifying bacteria, the cod of effluent was markedly decreased while the nitrification rate was very low. aerobic nitrifying granules were not appeared in the first bioreactor. in the other sbr system that was inoculated with aerobic granules culti ... | 2007 | 17990544 |
| [nitrification performance and microbial community analysis in carbon membrane-aerated biofilm reactor]. | a carbon membrane-aerated biofilm reactor was developed to treat nitrogenous inorganic wastewater. influent nh; -n concentrations and hrt were changed to investigate nitrification performance of reactor,oxygen utilization and nh4+ -n's removal loading. biofilm's surface characteristics and dominant bacteria of nitrifier were analyzed. the results show that under the conditions of intra-membrane pressure of 0.017 mpa, influent nh4+ -n of 50 mg/l and hrt of 8 h nh4+ -n removal efficiency reaches 9 ... | 2007 | 17990569 |
| experimental and simulation analysis of community structure of nitrifying bacteria in a membrane-aerated biofilm. | until now, only few attempts have been made to assess biofilm models simulating microenvironments in a biofilm. as a first step, we compare the microenvironment observed in a membrane aerated biofilm (mab) to that derived from a two-dimensional computational model with individual ammonia oxidizing bacteria (aob) and nitrite oxidizing bacteria (nob) embedded in a continuum eps matrix. gradients of oxygen were determined by means of microelectrodes. the change in nitrifying bacterial populations w ... | 2007 | 17546997 |
| [approaches of biological nitrogen removal in a single sequencing batch biofilm reactor]. | the conventional microorganism techniques and the molecule biological techniques such as pcr and dgge were utilized to study the approaches of biological nitrogen removal in a single sequencing batch biofilm reactor (sbbr). the main approach of biological nitrogen removal, no less than 65% of the total nh4(+)-n was removed in this approach, was composed of partial nitrification, anaerobic ammonium oxidation and denitrification. the second approach included twain processes such as partial nitrifi ... | 2007 | 18269000 |
| [characteristics of aerobic short-cut nitrification granular sludge]. | the physical properties and microbiological characteristics of aerobic short-cut granular sludge, which was cultivated in a lab-scale aerated upflow sludge bed (ausb) reactor, were investigated. when the short-cut nitrification process was performed stably, the ratios of vss/ ss of short-cut granules were kept at about 80%, the amount of granules with diameter larger than 1.0 mm was about 70% of the total, and the wet density of granules with diameter larger than 0.8mm was about 1022 kg/m3. the ... | 2007 | 18290425 |
| determination of growth rate and yield of nitrifying bacteria by measuring carbon dioxide uptake rate. | nitrifier growth parameters--the maximum growth rate (microamax) and yield (ya)--were estimated by measuring the rate of carbon dioxide uptake and additional rates of oxygen uptake and ammonia (or nitrite) use. batch tests in a combined titrimetric and offgas analyzer with enriched nitrobacter and nitrosomonas cultures and an activated sludge sample were performed. the measured microamax values for the nitrobacter and nitrosomonas cultures were 0.67 +/- 0.03 day(-1) and 0.54 +/- 0.09 day(-1), wh ... | 2007 | 18044361 |
| kinetic characterisation of an enriched nitrospira culture with comparison to nitrobacter. | nitrospira and nitrobacter are nitrite-oxidising bacteria commonly identified in nitrogen removal wastewater treatment plants. little is known about the growth parameters of nitrospira or the effects of environmental conditions or inhibitory compounds on nitrospira activity. these bacterial properties were investigated using an enriched nitrospira culture and an enriched nitrobacter culture or nitrobacter literature values. compared to nitrobacter, nitrospira was found to have a comparable optim ... | 2007 | 17553540 |
| feasibility of a membrane-aerated biofilm reactor to achieve single-stage autotrophic nitrogen removal based on anammox. | a laboratory-scale membrane-aerated biofilm bioreactor (mabr) equipped with non-woven fabrics support around the gas-permeable carbon tube was developed for single-stage autotrophic nitrogen removal based on partial nitrification and anaerobic ammonium oxidization. this reactor allowed air to be supplied through the microporous carbon tube wall to the biofilm that was supported by non-woven fabrics. the partial nitrification and consumption of dissolved oxygen occurred in the inner layer and ana ... | 2007 | 17590408 |
| [short-cut nitrification of landfill leachate by aerobic moving-bed biofilm reactor]. | short-cut nitrification process was studied to remove the ammonium nitrogen from the anaerobically pretreated leachate using aerobic moving-bed biofilm reactor (mbbr) at ambient temperature. the effect of do concentration, ph and c/n ratio on the ammonium removal efficiency and nitrite accumulation rate was investigated, respectively. experimental results showed that, more than 70% of ammonium removal efficiency and about 90% of nitrite accumulation rate could be achieved when the reaction condi ... | 2007 | 17633176 |
| nitrite-oxidizing bacteria guild ecology associated with nitrification failure in a continuous-flow reactor. | nitrification is an important process for nitrogen removal in many wastewater treatment plants, which requires the mutualistic oxidation of ammonia to nitrate by ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob). however, this process can be quite unpredictable because both guilds are conditionally sensitive to small changes in operating conditions. here, dynamics are examined within the nob guild in two parallel chemostats operated at low and high dilution rates (0.10 and 0. ... | 2007 | 17868364 |
| unraveling the source of nitric oxide emission during nitrification. | nitric oxide production was measured during nitrification in a laboratory-scale bioreactor, operated at conditions relevant to municipal nitrifying wastewater treatment plants. this study aims to determine which type of microorganism and which metabolic pathway is responsible for nitric oxide emission during nitrification. simulation studies were used to identify which pathway is the main source of nitric oxide emission, based on the following three hypothetical pathways for nitric oxide emissio ... | 2007 | 18198695 |
| nitrifying community analysis in a single submerged attached-growth bioreactor for treatment of high-ammonia waste stream. | this study investigated the nitrifying community structure in a single-stage submerged attached-growth bioreactor (sagb) that successfully achieved stable nitrogen removal over nitrite of a high-strength ammonia wastewater. the reactor was operated with intermittent aeration and external carbon addition (methanol). with influent ammonia and total kjeldahl nitrogen ranging from 537 to 968 mg/l and 643 to 1510 mg/l, respectively, 85% nitrogen removal was obtained, and effluent was dominated by nit ... | 2007 | 18198696 |
| identification of nitrifiers in a full-scale biological treatment system using fluorescent in situ hybridization. | diversity of nitrifying bacterial population was investigated in sludge samples taken from a full-scale biological wastewater treatment plant (wwtp) treating domestic wastewater by fluorescent in situ hybridization (fish) during seasonal operation. duplicate grab samples were collected in march 2003, june 2003, december 2003 and may 2004 from the aerobic tank of the treatment plant. fish results were interpreted with system performance in terms of bod5, tkn and no3-n removals and also with opera ... | 2007 | 17365322 |
| the phylogeny of the genus nitrobacter based on comparative rep-pcr, 16s rrna and nitrite oxidoreductase gene sequence analysis. | strains of nitrobacter mediate the second step in the nitrification process by oxidizing nitrite to nitrate. the phylogenetic diversity of the genus is currently not well investigated. in this study, a rep-pcr profile and the nearly complete 16s rrna gene sequence of 30 strains, comprising a wide physiological as well as ecological diversity and encompassing representatives of the four species, were determined. the sequence diversity of the 16s rrna gene between different species was low, indica ... | 2007 | 17208402 |
| diversity study of nitrifying bacteria in full-scale municipal wastewater treatment plants. | we hypothesize that activated-sludge processes having stable and complete nitrification have significant and similar diversity and functional redundancy among its ammonia- and nitrite-oxidizing bacteria, despite differences in temperature, solids retention time (srt), and other operating conditions. to evaluate this hypothesis, we examined the diversity of nitrifying bacterial communities in all seven water-reclamation plants (wrps) operated by metropolitan water reclamation district of greater ... | 2007 | 17254627 |
| molecular diversity of nitrite reductase genes (nirk) in nitrifying bacteria. | sequences of copper-containing nitrite reductase (nirk) genes obtained from completed nitrifier genome sequences were used to design polymerase chain reaction (pcr) primers to amplify partial nirk sequences from one nitrosomonas and four nitrosospira isolates. deduced nirk protein sequences were highly similar to other copper-containing nitrite reductases including conserved motifs. phylogenetic comparisons of nirk protein sequences placed orthologues from nitrosomonas, nitrosospira and nitrobac ... | 2007 | 17298375 |
| nitrifying bacterial communities in an aquaculture wastewater treatment system using fluorescence in situ hybridization (fish), 16s rrna gene cloning, and phylogenetic analysis. | aquaculture, especially shrimp farming, has played a major role in the growth of thailand's economy in recent years, as well as in many south east asian countries. however, the nutrient discharges from these activities have caused adverse impacts on the quality of the receiving waterways. in particular nitrogenous compounds, which may accumulate in aquaculture ponds, can be toxic to aquatic animals and cause environmental problems such as eutrophication. the mineralization process is well known, ... | 2007 | 17115448 |
| [sludge population optimisation in biological wastewater treatment systems through on-line control]. | the structure and function of activated sludge community were studied in an a/o pilot-scale plant treating actual domestic wastewater. fish results show the feasibility and effectiveness of sludge population optimisation. a/o process short-cut nitrification with process control of do and aeration based on do and ph on-line sensors can be achieved, and gradually eliminated nitrite oxidising bacteria, and therefore achieved nitrogen removal via the nitrite pathway. it can be realized sludge popula ... | 2007 | 17633177 |
| characterization and performance of constructed nitrifying biofilms during nitrogen bioremediation of a wastewater effluent. | constructed ammonium oxidizing biofilms (caob) and constructed nitrite oxidizing biofilms (cnob) were characterized during the bioremediation of a wastewater effluent. the maximum ammonium removal rate and removal efficiency in caob was 322 mg n-nh4+ m(-3) d(-1) and 96%, respectively, while in cnob a maximum removal rate of 255 mg n-nh4+ m(-3) d(-1) and a removal efficiency of 76% was achieved. both constructed biofilms on low-density polyester dacron support achieved removal efficiencies higher ... | 2007 | 17186207 |
| effect of free ammonia on the respiration and growth processes of an enriched nitrobacter culture. | the inhibitory effect of free ammonia (fa;nh(3)) on the metabolism of nitrobacter is investigated using a method that allows decoupling energy generation from growth processes. a lab-scale sequencing batch reactor (sbr) was operated for the enrichment of nitrobacter. fluorescent in situ hybridization (fish) analysis showed that 73% of the bacterial population in the reactor was nitrobacter, while no nitrospira was detected. batch tests were carried out to measure the oxygen uptake rate (our) by ... | 2007 | 17224173 |
| effects of substratum on the diversity and stability of ammonia-oxidizing communities in a constructed wetland used for wastewater treatment. | to study the relationship between the nature of the substratum and the diversity and stability of the ammonia-oxidizing microbial community in a constructed wetland for the treatment of wastewaters. | 2007 | 17953555 |
| phylogenomics and signature proteins for the alpha proteobacteria and its main groups. | alpha proteobacteria are one of the largest and most extensively studied groups within bacteria. however, for these bacteria as a whole and for all of its major subgroups (viz. rhizobiales, rhodobacterales, rhodospirillales, rickettsiales, sphingomonadales and caulobacterales), very few or no distinctive molecular or biochemical characteristics are known. | 2007 | 18045498 |
| plasmids of the prm/prf family occur in diverse rickettsia species. | the recent discoveries of the prf and prm plasmids of rickettsia felis and r. monacensis have contravened the long-held dogma that plasmids are not present in the bacterial genus rickettsia (rickettsiales; rickettsiaceae). we report the existence of plasmids in r. helvetica, r. peacockii, r. amblyommii, and r. massiliae isolates from ixodid ticks and in an r. hoogstraalii isolate from an argasid tick. r. peacockii and four isolates of r. amblyommii from widely separated geographic locations cont ... | 2008 | 18065613 |
| complete genome sequence of nitrobacter hamburgensis x14 and comparative genomic analysis of species within the genus nitrobacter. | the alphaproteobacterium nitrobacter hamburgensis x14 is a gram-negative facultative chemolithoautotroph that conserves energy from the oxidation of nitrite to nitrate. sequencing and analysis of the nitrobacter hamburgensis x14 genome revealed four replicons comprised of one chromosome (4.4 mbp) and three plasmids (294, 188, and 121 kbp). over 20% of the genome is composed of pseudogenes and paralogs. whole-genome comparisons were conducted between n. hamburgensis and the finished and draft gen ... | 2008 | 18326675 |
| dynamic aspects and controllability of the melissa project: a bioregenerative system to provide life support in space. | manmade ecosystems differ from their prototype biosphere by the principle of control. the earth biosphere is sustainable by stochastic control and very large time constants. by contrast, in a closed ecosystem such as the micro-ecological life support system alternative (melissa system) developed by the european space agency for space exploration, a deterministic control is a prerequisite of sustainable existence. melissa is an integrated sum of interconnected biological subsystems. on one hand, ... | 2008 | 18592407 |
| t-rflp detection of nitrifying bacteria in a fluidized bed reactor of achieving simultaneous nitrification-denitrification. | steady simultaneous nitrification-denitrification (snd) was achieved in a fluidized bed reactor (fbr) by the control of do concentration without physical separation of the aerobic and anoxic zones. the performance and composition of nitrifying bacteria were examined in this study. the ammonium removal efficiency was higher than 80% and the do concentration (1-5 mg l(-1)) had little influence on it. more than 50% total nitrogen (tn) removal efficiency was achieved when do was less than 3 mg l(-1) ... | 2008 | 18313099 |
| response of nitrobacter spp. ribosomal gene and transcript abundance following nitrite starvation and exposure to mechanistically distinct inhibitors. | the nitrobacter spp. rrna gene (rdna) and relative rrna transcript abundance (rrnat/rdna ratio) were evaluated in response to sudden changes in the nitrite oxidation rate. the rdna abundance poorly indicated sudden transitions in the rate, whereas the relative rrnat abundance usually varied quickly and significantly. in response to changes in nitrite concentration, 8 h were required for the rrnat/rdna ratio to transition from a minimum value at nitrite starvation (approximately 0.07) to a maximu ... | 2008 | 18323120 |