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 ...200516023572
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 ...200516042242
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 ...200516204501
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 ...200516303163
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 ...200616310272
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 ...200616321514
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 ...200516329914
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 ...200516332337
influence of inorganic nitrogen management regime on the diversity of nitrite-oxidizing bacteria in agricultural grassland 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 ...200516332819
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 ...200516332848
production of no(2) and n(2)o by nitrifying bacteria at reduced concentrations of oxygen.pure cultures of the marine ammonium-oxidizing bacterium nitrosomonas sp. were grown in the laboratory at oxygen partial pressures between 0.005 and 0.2 atm (0.18 to 7 mg/liter). low oxygen conditions induced a marked decrease in the rate for production of no(2), from 3.6 x 10 to 0.5 x 10 mmol of no(2) per cell per day. in contrast, evolution of n(2)o increased from 1 x 10 to 4.3 x 10 mmol of n per cell per day. the yield of n(2)o relative to no(2) increased from 0.3% to nearly 10% (moles of n i ...198016345632
serological diversity of nitrobacter spp. from soil and aquatic habitats.serotypic diversity among nitrobacter spp. isolates is greater than previously reported. typing with fluorescent antibodies prepared against 11 nitrobacter spp. cultures isolated from soil and water placed the isolates into six serogroups. when these fluorescent antibodies were applied to a group of 16 additional isolates, 8 were identifiable by cross-reaction to 3 of the 11 fluorescent antibodies. some nitrite-oxidizing enrichment cultures from different habitats contained cross-reacting strain ...198116345749
methane oxidation by nitrosococcus oceanus and nitrosomonas europaea.chemolithotrophic ammonium-oxidizing and nitrite-oxidizing bacteria including nitrosomonas europaea, nitrosococcus oceanus, nitrobacter sp., nitiospina gracilis, and nitrococcus mobilis were examined as to their ability to oxidize methane in the absence of ammonium or nitrite. all ammonium oxidizers tested had the ability to oxidize significant amounts of methane to co(2) and incorporate various amounts into cellular components. none of the nitrite-oxidizing bacteria were capable of methane oxid ...198316346190
inhibition of chemoautotrophic nitrification by sodium chlorate and sodium chlorite: a reexamination.the oxidation of nh(4) by nitrosomonas europaea was insensitive to 10 mm naclo(3) (sodium chlorate) but was strongly inhibited by naclo(2) (sodium chlorite; k(i), 2 mum). the oxidation of no(2) by nitrobacter winogradskyi was inhibited by both clo(3) and clo(2) (k(i) for clo(2), 100 mum). n. winogradskyi reduced clo(3) to clo(2) under both aerobic and anaerobic conditions, and as much as 0.25 mm clo(2) was detected in the culture filtrate. in mixed n. europaea-n. winogradskyi cell suspensions, t ...198316346262
bicarbonate uptake by nitrifiers: effects of growth rate, ph, substrate concentration, and metabolic inhibitors.the ratios of bicarbonate uptake to substrate oxidation were measured for three genera of nitrifying bacteria. the ratios for the two ammonium oxidizers tested were essentially the same; 0.0863 +/- 0.0055 and 0.0868 +/- 0.0091 mumol of bicarbonate were taken up per umol ammonium oxidized for nitrosomonas europaea and a nitrosospira strain, respectively. for nitrobacter sp., a ratio of 0.0236 +/- 0.0013 mumol of bicarbonate taken up per umol of nitrite oxidized was obtained. cells were grown in s ...198416346673
inhibitor evaluation with immobilized nitrobacter agilis cells.nitrobacter agilis was entrapped in calcium alginate beads and used as a floating bed supplied with a continuous flow of nitrite medium. complete nitrite oxidation was achieved within 30 h, and the system could be maintained for at least 210 h. the immobilized nitrobacter system was subjected to sulfur oxyanions, acidity, and metal ions. thiosulfate and tetrathionate (up to 20 mm each) did not inhibit the nitrite oxidation activity. a low ph of 4.2 resulted in the complete cessation of nitrite o ...198616347230
nitrifying bacteria in wastewater reservoirs.deep wastewater reservoirs are used throughout israel to store domestic wastewater effluents for summer irrigation. these effluents contain high concentrations of ammonia (</=5 mm) that are frequently toxic to photosynthetic microorganisms and that lead to development of anoxic conditions. population dynamics of nitrifying bacteria and rates of nitrification were studied in two wastewater reservoirs that differed in organic load and degree of oxygenation and in the laboratory under controlled co ...198716347319
an acidophilic and a neutrophilic nitrobacter strain isolated from the numerically predominant nitrite-oxidizing population of an acid forest soil.two physiologically and serologically distinct strains of chemoautotrophic nitrite-oxidizing bacteria were isolated as numerically predominant members of the nitrite-oxidizer population of an undisturbed forest soil with a ph range of 4.3 to 5.2. one isolate responded as a neutrophile, characteristic of the family nitrobacteraceae, and cross-reacted strongly with fluorescent antibody to nitrobacter strain engel. the second isolate responded as an acidophile in pure culture, demonstrated maximal ...198816347664
competition for ammonium between nitrifying and heterotrophic bacteria in dual energy-limited chemostats.the absence of nitrification in soils rich in organic matter has often been reported. therefore, competition for limiting amounts of ammonium between the chemolithotrophic ammonium-oxidizing species nitrosomonas europaea and the heterotrophic species arthrobacter globiformis was studied in the presence of nitrobacter winogradskyi in continuous cultures at dilution rates of 0.004 and 0.01 h. ammonium limitation of a. globiformis was achieved by increasing the glucose concentration in the reservoi ...199116348588
effects of grazing by flagellates on competition for ammonium between nitrifying and heterotrophic bacteria in chemostats.the enhanced mineralization of organic nitrogen by bacteriophagous protozoa is thought to favor the nitrification process in soils, in which nitrifying bacteria have to compete with heterotrophic bacteria for the available ammonium. to obtain more insight into this process, the influence of grazing by the bacteriovorous flagellate adriamonas peritocrescens on the competition for limiting amounts of ammonium between the ammonium-oxidizing species nitrosomonas europaea and the heterotrophic specie ...199216348722
competition for ammonium between nitrifying and heterotrophic bacteria in continuously percolated soil columns.although the absence of nitrate formation in grassland soils rich in organic matter has often been reported, low numbers of nitrifying bacteria are still found in these soils. to obtain more insight into these observations, we studied the competition for limiting amounts of ammonium between the chemolithotrophic ammonium-oxidizing species nitrosomonas europaea and the heterotrophic species arthrobacter globiformis in the presence of nitrobacter winogradskyi with soil columns containing calcareou ...199216348787
quantitative determination of the spatial distribution of nitrosomonas europaea and nitrobacter agilis cells immobilized in kappa-carrageenan gel beads by a specific fluorescent-antibody labelling technique.a novel technique, combining labelling and stereological methods, for the determination of spatial distribution of two microorganisms in a biofilm is presented. cells of nitrosomonas europaea (atcc 19718) and nitrobacter agilis (atcc 14123) were homogeneously distributed in a kappa-carrageenan gel during immobilization and allowed to grow out to colonies. the gel beads were sliced in thin cross sections after fixation and embedding. a two-step labelling method resulted in green fluorescent colon ...199316348970
effects of grazing by flagellates on competition for ammonium between nitrifying and heterotrophic bacteria in soil columns.the enhanced mineralization of immobilized nitrogen by bacteriophagous protozoa has been thought to favor the nitrification process in soils in which nitrifying bacteria must compete with heterotrophic bacteria for the available ammonium. to obtain more insight into this process, the influence of grazing by the flagellate adriamonas peritocrescens on the competition for ammonium between the chemolithotrophic species nitrosomonas europaea and the heterotrophic species arthrobacter globiformis in ...199316348988
selective inhibition of ammonium oxidation and nitrification-linked n(2)o formation by methyl fluoride and dimethyl ether.methyl fluoride (ch(3)f) and dimethyl ether (dme) inhibited nitrification in washed-cell suspensions of nitrosomonas europaea and in a variety of oxygenated soils and sediments. headspace additions of ch(3)f (10% [vol/vol]) and dme (25% [vol/vol]) fully inhibited no(2) and n(2)o production from nh(4) in incubations of n. europaea, while lower concentrations of these gases resulted in partial inhibition. oxidation of hydroxylamine (nh(2)oh) by n. europaea and oxidation of no(2) by a nitrobacter s ...199316349011
nitrospira-like bacteria associated with nitrite oxidation in freshwater aquaria.oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the genus nitrobacter which are members of the alpha subdivision of the class proteobacteria. in order to identify bacteria responsible for nitrite oxidation in aquaria, clone libraries of rrna genes were developed from biofilms of several freshwater aquaria. analysis of the rdna libraries, along with results from denaturing gradient gel electrophoresis (dgge) on frequently sampled biofilms, indicated the ...199816349486
reliable procedure for silica gel preparation.a simple and reliable method is described for preparation of silica gel media for nitrosomonas and nitrobacter species.197216349945
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 ...200516381147
pilot-scale studies on biological treatment of hypersaline wastewater at low 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 ...200516459784
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 ...200616460781
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 ...200616478447
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 ...200616517654
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 ...200616530803
production of no and n(inf2)o by pure cultures of nitrifying and denitrifying bacteria during changes in aeration.peak emissions of no and n(inf2)o are often observed after wetting of soil. the reactions to sudden changes in the aeration of cultures of nitrifying and denitrifying bacteria with respect to no and n(inf2)o emissions were compared to obtain more information about the microbiological aspects of peak emissions. in continuous culture, the nitrifier nitrosomonas europaea and the denitrifiers alcaligenes eutrophus and pseudomonas stutzeri were cultured at different levels of aeration (80 to 0% air s ...199716535707
dissimilatory nitrate reduction in anaerobic sediments leading to river nitrite accumulation.recent studies on northern ireland rivers have shown that summer nitrite (no(inf2)(sup-)) concentrations greatly exceed the european union guideline of 3 (mu)g of n liter(sup-1) for rivers supporting salmonid fisheries. in fast-flowing aerobic small streams, no(inf2)(sup-) is thought to originate from nitrification, due to the retardation of nitrobacter strains by the presence of free ammonia. multiple regression analyses of no(inf2)(sup-) concentrations against water quality variables of the si ...199716535749
carbon and energy sources for the nitrifying autotroph nitrobacter.delwiche, c. c. (university of california, davis), and m. s. finstein. carbon and energy sources for the nitrifying autotroph nitrobacter. j. bacteriol. 90:102-107. 1965.-the effect of various organic compounds on the growth and metabolism of the obligatively autotrophic nitrifying organism nitrobacter was studied. a slight stimulation of both nitrification and growth was obtainable with a number of organic amendments, including yeast extract, vitamin free casamino acids, and some amino acids. d ...196516562002
permeability of nitrobacter agilis to organic compounds.ida, s. (cornell university, ithaca, n.y.), and m. alexander. permeability of nitrobacter agilis to organic compounds. j. bacteriol. 90:151-156. 1965.-none of a variety of inorganic ions or organic compounds served as a sole energy source for the growth of nitrobacter agilis, and the test substrates were not oxidized by either intact cells or extracts of the obligate chemoautotroph. the organic substances did not serve as sole carbon sources for the bacterium in a synthetic medium, and they fail ...196516562012
stimulation of nitrobacter agilis by biotin.krulwich, terry a. (goucher college, baltimore, md.), and helen b. funk. stimulation of nitrobacter agilis by biotin. j. bacteriol. 90:729-733. 1965.-addition of biotin to nitrite-mineral medium greatly stimulated the autotrophic growth of four strains of nitrobacter agilis. comparisons of cultures of the organisms grown in parallel at 30 c in nitrite medium and in the medium supplemented with 150 mmug of biotin per ml showed that the vitamin promoted: (i) 2- to 4-fold greater rates of utilizati ...196516562074
[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 ...200616572857
phosphorylation coupled to nitrite oxidation by particles from the chemoautotroph, nitrobacter agilis. 196016590668
development and calibration of a nitrification pde model based on experimental data issued from biofilter treating drinking 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 ...200616598794
[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 ...200616599123
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 ...200616673416
[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 ...200616686198
competition between nitrospira spp. and nitrobacter spp. in nitrite-oxidizing 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 ...200616703620
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 ...200616749447
[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 ...200616767988
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.200616874545
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 ...200616903283
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 ...200616913917
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 ...200616939105
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 ...200617028023
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, ...200717115448
[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 ...200617117645
[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 ...200617117646
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 ...200717186207
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 ...200717208402
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 ...200717224173
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 ...200717254627
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 ...200717298375
[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 ...200617304844
[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 ...200617304848
[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 ...200617304849
[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 ...200617326454
[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 ...200617328142
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 ...200717365322
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 ...200717546997
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 ...200717553540
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 ...200717590408
[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 ...200717633176
[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 ...200717633177
the isolation of nitrosomonas and nitrobacter by the single cell technique. 193017799073
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. ...200717868364
[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 ...200717891957
[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 ...200717926400
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 ...200717951872
effects of substratum on the diversity and stability of ammonia-oxidizing communities in a constructed wetland used for wastewater 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.200717953555
[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 ...200717990544
[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 ...200717990569
distribution of nitrosomonas europaea and nitrobacter winogradskyi in an autotrophic nitrifying biofilm reactor as depicted by molecular analyses and mathematical modelling.the autotrophic two-species biofilm from the packed bed reactor of a life-support system, containing nitrosomonas europaea atcc 19718 and nitrobacter winogradskyi atcc 25391, was analysed after 4.8 years of continuous operation performing complete nitrification. real-time quantitative polymerase chain reaction (q-pcr) was used to quantify n. europaea and n. winogradskyi along the vertical axis of the reactor, revealing a spatial segregation of n. europaea and n. winogradskyi. the main parameters ...200818023467
first exploration of nitrobacter diversity in soils by a pcr cloning-sequencing approach targeting functional gene nxra.nitrite oxidoreductase (nxr) is the key enzyme responsible for the oxidation of no(2)(-) to no(3)(-) in nitrite-oxidizing bacteria. for the first time a molecular approach for targeting the nxra gene was developed, encoding the catalytic subunit of the nxr, to study diversity of nitrobacter-like organisms based on the phylogeny of nxra gene sequences in soils. nxra sequences of the nitrobacter strains analysed (nitrobacter hamburgensis, nitrobacter vulgaris, nitrobacter winogradskyi, nitrobacter ...200818031541
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 ...200718044361
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.200718045498
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 ...200818065613
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 ...200718198695
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 ...200718198696
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 ...200718198701
development and application of a pcr-denaturing gradient gel electrophoresis tool to study the diversity of nitrobacter-like nxra sequences in soil.a new pcr-denaturing gel gradient electrophoresis (dgge) tool based on the functional gene nxra encoding the catalytic subunit of the nitrite oxidoreductase in nitrite-oxidizing bacteria (nob) has been developed. the first aim was to determine if the primers could target representatives of nob genera: nitrococcus and nitrospira. the primers successfully amplified nxra gene sequences from nitrococcus mobilis, but not from nitrospira marina. the second aim was to develop a pcr-dgge tool to charact ...200818199085
activated sludge operational regime has significant impact on the type of nitrifying community and its nitrification rates.a nitrifying sequencing batch reactor, operated under alternating anoxic/aerobic conditions achieved twice the nitrification rates of its strictly aerobic counterpart. microbial populations in both reactors were examined with fluorescent in situ hybridization (fish) and kinetic batch studies to determine the effects of ammonium, nitrite, and oxygen. fish revealed a dominance of rapid nitrifiers like nitrosomonas and nitrobacter (79.5% of the nitrifying population) in the alternating reactor, com ...200818222524
[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 ...200718269000
[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 ...200718290425
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) ...200818313099
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 ...200818323120
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 ...200818326675
distinctive microbial ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor.biological nitrogen removal (bnr) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). the goal of this study was to investigate the microbial ecology, biokinetics, and stability of partial nitrification. stable long-term partial nitrification resulting in 82.1 +/- 17.2% ammonia oxidation, primarily to nitrite (77.3 +/- 19.5% of the ammonia oxidized) was achieved in a lab-scale bioreactor by ...200818393313
process efficiency and microbial monitoring in mbr (membrane bioreactor) and casp (conventional activated sludge process) treatment of tannery this study a pilot-scale membrane bioreactor (mbr) and a conventional activated sludge plant (casp), treating the same tannery wastewaters and in the same operating conditions, have been compared in order to evaluate the overall treatment efficiency, the presence and distribution of gram negative bacteria and the kinetics of nitrifying bacteria. process efficiency was evaluated in terms of organic and nitrogen compounds: the mbr showed a higher cod removal (+4%) and a more stable and complete ...200818499451
kinetics of biofilm nitrification.the reaction rates (r(nh(4) (+) ) and r(no(2) (-) )) in the two-step nitrification reaction were measured in a fluidized-sand-bed biofilm reactor under a range of steady-state conditions with respect to bulk nh(4) (+), no(2) (-), and o(2) concentrations. it was shown from theory and experiment that under low nh(4) (+) concentration conditions, if the o(2)/nh(4) (+) concentration ratio in the bulk liquid is less than the stoichiometric coefficient (3.4 mg/mg), then oxygen will be rate limiting. i ...198218546355
achieving the nitrite pathway using aeration phase length control and step-feed in an sbr removing nutrients from abattoir wastewater.aeration phase length control and step-feed of wastewater are used to achieve nitrogen removal from wastewater via nitrite in sequencing batch reactors (sbr). aeration is switched off as soon as ammonia oxidation is completed, which is followed by the addition of a fraction of the wastewater that the sbr receives over a cycle to facilitate denitrification. the end-point of ammonia oxidation is detected from the on-line measured ph and oxygen uptake rate (our). the method was implemented in an sb ...200818553405
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, ...200818592407
growth and substrate consumption of nitrobacter agilis cells immobilized in carrageenan: part 1. dynamic modeling.the modeling of the growth of nitrobacter agilis cell immobilized in kappa-carrageenan is presented. a detailed description is given of the modeling of internal diffusion and growth of cells in the support matrix in addition to external mass transfer resistance. the model predicts the substrate and biomass profiles in the support as well as the macroscopic oxygen consumption rate of the immobilized biocatalyst in time. the model is tested by experiments with continuously operated airlift loop re ...199118600755
growth and substrate consumption of nitrobacter agilis cells immobilized in carrageenan: part 2. model evaluation.a dynamic model that predicts substrate and biomass concentration profiles across gel beads and from that the overall substrate consumption rate by the gel beads containing growing cells was evaluated with immobilized nitrobacter agilis cells in an airlift loop reactor with oxygen as the limiting substrate. the model predictions agreed well with the observed oxygen consumption rates at three different liquid phase oxygen concentrations. image analysis showed that 90% of the immobilized cells aft ...199118600756
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