nitrifying genera in activated sludge may influence nitrification rates.sequencing batch reactors were acclimated under aerobic and alternating anoxic/aerobic conditions. greater nitrification rates in the alternating reactor were investigated by comparing environmental conditions. in the alternating reactor, ph, alkalinity, oxygen, and nitrite were higher at the onset of aerobic nitrification. kinetic studies and batch tests, with biomass developed under aerobic and alternating conditions, revealed that these factors were insufficient to explain the divergent nitri ...200818605378
[nitrifiers accumulation with reject water and bio-augmentation for nitrification of sewage at short srt].sequencing batch reactor, treating simulated municipal wastewater for n removal and operated at near the minimum srt (solids retention time) for nitrification (in reactor 2), was seeded daily with nitrifying biomass accumulated with reject water (in reactor 1) came from xi' an dengjiacun wastewater treatment plant. comparison of the nitrification ability, the characteristics of the activated sludge before seeding and after seeding was made. the experiment result shows that, the maximum nitrifica ...200818613501
co-immobilized nitrosomonas europaea and nitrobacter agilis cells: validation of a dynamic model for simultaneous substrate conversion and growth in kappa-carrageenan gel beads.a dynamic model for two microbial species immobilized in a gel matrix is presented and validated with experiments. the model characterizes the nitrification of ammonia with nitrosomonas europaea and nitrobacter agilis co-immobilized in k-carrageenan gel beads. the model consists of kinetic equations for the microorganisms and mass transfer equations for the substrates and products inside and outside the gel beads. the model predicts reactor bulk concentrations together with the substrate consump ...199418615529
effects of diffusion limitation on immobilized nitrifying microorganisms at low temperatures.activation energies of suspended and immobilized nitrifying bacteria were determined and compared to determine if diffusion limitation results in decreased sensitivity for temperature. the activation energy for the respiration activity of suspended nitrosomonas europaea and nitrobacter agilis was found to be 86.4 and 58.4 kj mol(-1), respectively. the activation energy for oxygen diffusion in the support material, kappa-carrageenan, determined from the effect of temperature on the effective diff ...199518623045
steady-state solution of a two-species biofilm problem.through a thorough investigation of the boundary conditions for a general two-species biofilm model, a simple and fast method for solving the steady-state case is developed and presented. the methods used may be extended to biofilm models in which more than two species are considered. four different sets of boundary conditions are possible for the two-species biofilm model. each set is shown to be asymptotically stable. a biofilm model describing the competition between autotrophic and heterotro ...199618627076
d-lactate metabolism and the obligate requirement for co2 during growth on nitrite by the facultative lithoautotroph nitrobacter hamburgensis.nitrobacter hamburgensis x14 is a facultative lithoautotroph that conserves energy from the oxidation of nitrite (no(-)2) and fixes carbon dioxide (co(2)) as its sole source of carbon. the availability of the n. hamburgensis x14 genome sequence initiated a re-examination of its mixotrophic and organotrophic potential, as genes encoding three flavin-dependent oxidases were identified that may function to oxidize lactate, providing energy and carbon for growth. the response of n. hamburgensis to d ...200818667580
application of high rate nitrifying trickling filters for potable water treatment.the interference of ammonia with chlorination is a prevalent problem encountered by water treatment plants located throughout south east asia. the efficacy of high rate, plastic-packed trickling filters as a pre-treatment process to remove low concentrations of ammonia from polluted surface water was investigated. this paper presents the findings from a series of pilot experiments, which were designed to investigate the effect of specific conditions-namely low ammonia feed concentrations (0.5-5. ...200818752823
effect of oxygen gradients on the activity and microbial community structure of a nitrifying, membrane-aerated biofilm.shortcut nitrogen removal, that is, removal via formation and reduction of nitrite rather than nitrate, has been observed in membrane-aerated biofilms (mabs), but the extent, the controlling factors, and the kinetics of nitrite formation in mabs are poorly understood. we used a special mab reactor to systematically study the effects of the dissolved oxygen (do) concentration at the membrane surface, which is the biofilm base, on nitrification rates, extent of shortcut nitrification, and microbia ...200818767185
[control of shortcut nitrification in sbbr with adequate oxygen supply].at the high level of dissolved oxygen (do) in sequencing batch biofilm reactor (sbbr), the approach and mechanism for realizing shortcut nitrification were researched. landfill leachate was used as handling of object, the mainly environment parameters of the reactor were controlled as follow: do 5 mg/l, ph 7.0, temperature 25 degrees c, adopted all drainage mode and 12-hour cycle influent. through mathematical derivation and modeling analysis, determined free ammonia (fa), co2 and hno2 as the di ...200818828367
expression of a putative nitrite reductase and the reversible inhibition of nitrite-dependent respiration by nitric oxide in nitrobacter winogradskyi nb-255.the nitrite oxidizing alphaproteobacterium, nitrobacter winogradskyi, primarily conserves energy from the oxidation of nitrite (no(2)(-))to nitrate (no(3)(-)) through aerobic respiration. almost 20 years ago, no-dependent nadh formation was reported to occur in both aerobic and anaerobic cell suspensions of n. winogradskyi strain 'agilis', suggesting that no oxidation might contribute to energy conservation by nitrobacter. recently, the n. winogradskyi nb-255 genome was found to contain a gene ( ...200818973623
exogenous respiration in nitrobacter. 196018990780
molecular characterization of microbial populations in groundwater sources and sand filters for drinking water full-scale drinking water production from groundwater, subsurface aeration is an effective means of enhancing the often troublesome process of nitrification. until now the exact mechanism, however, has been unknown. by studying the microbial population we can improve the understanding of this process. denaturing gradient gel electrophoresis of pcr-amplified 16s rrna gene fragments of bacteria, archaea and ammonia-oxidizing bacteria was used to characterize the microbial populations in raw gro ...200918995879
emerging models for nitrogen removal in treatment textbooks tell a simple story about nitrification and denitrification. classic nitrification-denitrification theory begins with the bacterial genera nitrosomonas and nitrobacter performing ammonia and nitrite oxidation, respectively. then facultative or obligate anaerobic bacteria denitrify by oxidizing organic carbon with nitrate. recent advances in environmental microbiology have revealed previously unknown bacteria and pathways in the nitrogen cycle that tell a far more complex st ...200819004390
sustainable nitrogen removal from wastewater with the hybrid membrane biofilm process (hmbp): bench-scale studies.the hybrid membrane biofilm process (hmbp) is a novel approach to achieving total nitrogen removal from wastewater. it incorporates air-supplying, hollow-fiber membranes into a conventional activated sludge tank, where bulk aeration is suppressed. a nitrifying biofilm grows on the membranes and exports nitrite and nitrate to the anoxic bulk liquid, where suspended heterotrophic bacteria denitrify using influent bod as an electron donor. bench scale tests were used to assess the performance of th ...200819029710
activated packed bed bioreactor for rapid nitrification in brackish water hatchery systems.a packed bed bioreactor (pbbr) was developed for rapid establishment of nitrification in brackish water hatchery systems in the tropics. the reactors were activated by immobilizing ammonia-oxidizing (amonpcu-1) and nitrite-oxidizing (nionpcu-1) bacterial consortia on polystyrene and low-density polyethylene beads, respectively. fluorescence in situ hybridization demonstrated the presence of autotrophic nitrifiers belong to nitrosococcus mobilis, lineage of beta ammonia oxidizers and nitrite oxid ...200919039611
effect of acetate on nitrite oxidation in mixed-population biofilms.while ammonia oxidation has been widely studied, nitrite oxidation is still not well understood. to study the effect of organics on nitrite oxidation, one control group and four treatment groups were designed with sodium acetate (c) to nitrite (n) ratios of 0, 0.44, 0.88, 4.41, and 8.82. normal nitrite oxidization reactions were performed when c/n=0, but nitrite oxidization and partial denitrification occurred with low c/n ratios (0.44 or 0.88). at high c/n ratios (4.41 or 8.82), we mainly obser ...200819134555
investigation of the microbial community structure and activity as indicators of compost stability and composting process a bid to identify suitable microbial indicators of compost stability, the process evolution during windrow composting of poultry manure (pm), green waste (gw) and biowaste was studied. treatments were monitored with regard to abiotic factors, respiration activity (determined using the sour test) and functional microflora. the composting process went through typical changes in temperature, moisture content and microbial properties, despite the inherent feedstock differences. nitrobacter and pa ...200919136252
study on membrane fouling of submerged membrane bioreactor in treating bathing wastewater.a pilot-scale submerged membrane bioreactor (mbr) was used to treat the bathing wastewater for more than 90 d. several factors affecting membrane fouling were studied, including the variation in transmembrane pressure (tmp), changes in extracellular polymeric substance (eps), and distribution of membrane resistance (r). the relationships between r and eps concentration were found to be r = 0.00008 (eps(s)) 2915 in the mixed liquor (eps(s)) and r = 0.2853 (epsm)--0.824 on the membrane surface (ep ...200819143338
[reactivation characteristics of stored aerobic nitrifying granules].a sequencing batch airlift reactor (sbar) was conducted to study the performance of physical characteristics and respirometric activities during reactivation of aerobic granules after a 2-month storage time. results showed that the color of the aerobic granules had completely become dark, the size and settleability did hardly change during the storage period. the color turned to be brownish-yellowish when the reactor was restarted for 2 weeks. the mlss, granule size, and settleability increased ...200819186813
[characteristic and prospects of heterotrophic nitrification].nitrification is a key step in the global nitrogen cycle. classically, nitrifying bacteria are chemoautotroph. recently, bacteria that have the ability of heterotrophic nitrification have been intensively studied as potential microorganisms that may be used to overcomeproblems inherent in the conventional method. this review gives a broad overview of the current status of heterotrophic nitrification including the heterotrophic species which nitrify actively, optimal condition for nitrification, ...200819186843
in situ characterization of nitrifying biofilm: minimizing biomass loss and preserving perspective.methods for characterizing nitrifying bacteria within biofilms are of key importance to understand and optimize the nitrification kinetics of attached growth treatment facilities. in this work, we propose an analytical protocol based upon environmental scanning electron microscopy (esem) and confocal laser scanning microscopy (cslm) in combination with fluorescent in situ hybridization (fish) to characterize the structure of nitrifying biofilm as it remains attached to the original reactor subst ...200919217138
nitrifying community structures and nitrification performance of full-scale municipal and swine wastewater treatment plants.this study evaluated nitrification performance and microbial ecology of nitrifying sludge in two full-scale wastewater treatment plants (wwtps) including a municipal wwtp treating 20mgnl(-1) of ammonium and a swine wwtp treating 220mgnl(-1) of ammonium. these two plants differed in both wastewater characteristics and operating parameters, such as influent cod, tkn, ammonium, hydraulic retention time, and solids retention time, even though both plants achieve >85% nitrification efficiency. by emp ...200919246073
vertical partitioning and expression of primary metabolic genes in a thermophilic microbial mat.a thermophilic microbial mat with a relatively simple morphological composition was used to study the expression of key metabolic genes between mat layers. mats comprised roseiflexus castenholzii, synechococcus sp., a sphingomonas-like proteobacterial taxon and an unidentified member of the thermotogae as determined by 16s rrna phylotypes. the diversity of expressed loci for key genes involved in oxygenic photosynthesis (cbbl), anoxygenic photosynthesis (pufm) and nitrogen fixation (nifh) was as ...200919347567
[effect of intermittent aeration on growth kinetics of nitrifiers and mechanism for no2- accumulation].in order to investigate shortcut nitrification, an intermittent-aeration sbr was employed to treat the domestic wastewater containing low concentration of nh4+ . the results shows that under the srts of 10, 5, 2.5 and 1.25 d, no2- produced in effluent were built up to 18, 19, 14 and 5 mg/l, respectively, with accumulation ratio of 73%, 85%, 91% and 78% respectively. as to the continuous-aeration sbr, however, the no2- accumulation ratios were only 14%, 21%, 31% and 34%. in addition, the correspo ...200919353862
[effects of influent flow distribution ratio on nitrogen removal in step-feed a/o process].in order to optimize the utilization of influent carbon source, a feeding pattern so-called "coefficient of influent flow rate" was adopted in a pilot-scale step-feed a/o process treating domestic wastewater. the effects of influent flow distribution ratio on nitrogen removal efficiency were investigated when the reactor was operated at different loading rates and cod/tkn ratio of 3, 5, 7, 9, 11, 13, respectively. the experiment results indicated that the wasting of nitrification capacity occurr ...200919353864
greenhouse gas microbiology in wet and dry straw crust covering pig slurry.liquid manure (slurry) storages are sources of gases such as ammonia (nh(3)) and methane (ch(4)). danish slurry storages are required to be covered to reduce nh(3) emissions and often a floating crust of straw is applied. this study investigated whether physical properties of the crust or crust microbiology had an effect on the emission of the potent greenhouse gases ch(4) and nitrous oxide (n(2)o) when crust moisture was manipulated ("dry", "moderate", and "wet"). the dry crust had the deepest ...200919398529
[competition and optimization of aob and nob for domestic wastewater treatment at normal temperatures].at normal temperature of 19 degrees c +/- 1 degree c and seed sludge from the system of conventional nitrogen removal via nitrate composed of both ammonia oxidizing bacteria (aob) and nitrite oxidizing bacteria (nob), the competition and optimization of aob and nob was investigated in a lab-scale sbr treating domestic wastewater. the reactor was operated under the aeration rate of 40 l/h with the average do concentration below 1.0 mg/l, and combined with the control of aeration time, i.e., aerat ...200919558114
[implement of completely autotrophic nitrogen removal in egsb reactor and its operation optimization].an expanded granular sludge bed (egsb) reactor inoculated simultaneously with aerobic ammonium oxidation sludge and anaerobic ammonium oxidation sludge were start-up to enrich completely autotrophic nitrogen removal granular sludge. total nitrogen (tn) removal rate reached 0.101 kg x (m3 x d)(-1). based on hypothesis of boundary layer, the transfer process between granular sludge and bulk liquid was modified, which was coupled with substance transfer process in granular sludge and aerobic ammoni ...200919558118
[functional microbial community in a membrane-aerated biofilm reactor operated for completely autotrophic nitrogen removal].the 16s rdna-based molecular technique was applied to investigate the functional microbial community of a membrane-aerated biofilm bioreactor (mabr) that was used for completely autotrophic nitrogen removal over nitrite (canon). the relationships among two kinds of key bacteria responsible for canon: aerobic ammonia-oxidizing bacteria (aob) and anammox bacteria, and their possible distributions in the mab were discussed based on the microbial community analysis. fish analysis showed the existenc ...200919558119
fluctuation of microbial activities after influent load variations in a full-scale sbr: recovery of the biomass after starvation.due to variations in the production levels, a full-scale sequencing batch reactor (sbr) for post-treatment of tannery wastewater was exposed to low and high ammonia load periods. in order to study how these changes affected the n-removal capacity, the microbiology of the reactor was studied by a diverse set of techniques including molecular tools, activity tests, and microbial counts in samples taken along 3 years. the recover capacity of the biomass was also studied in a lab-scale reactor opera ...200919629470
effect of organic carbon on nitrification efficiency and community composition of nitrifying biofilms.the effects of organic carbon/inorganic nitrogen (c/n) ratio on the nitrification processes and the community shifts of nitrifying biofilms were investigated by kinetic comparison and denaturing gradient gel electrophoresis (dgge) analysis. the results showed that the nitrification rate decreased with an increasing organic concentration. however, the effect became weak when the carbon concentration reached a sufficiently high level. denitrification was detected after organic carbon was added. th ...200919634453
[ecological engineering experiment for jinshan lake in zhenjiang base on techniques of immobilized nitrogen cycling bacteria].nitrogen cycling bacteria, including ammonifying, nitrobacteria, nitrosobacteria and denitrifying bacteria were screened, carrier was made and immobilized nitrogen cycling bacteria (incb) was prepared. the results demonstrated that ammonifying, nitrobacteria, nitrosobacteria and denitrifying bacteria were increased markedly in the experimental areas and root zone of aquatic plants by releasing of incb. the results also showed that the average removal efficiencies for total n (tn), nh4(+) -n, no3 ...200919662841
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 ...200219709262
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 ...200319719689
[community structure and kinetics characterization of enriched nitrifiers cultivated with reject water].the community of nitrifiers cultivated with reject water were investigated by fluorescent in situ hybridization (fish) performed with 16s rrna-targeted oligonucleotide probes, and the kinetic properties such as temperature correction factor taun and the half saturation coefficient k(n) were also investigated. the results showed that the percentage of ammonia oxidizing bacteria (aob) and nitrite oxidizing bacteria (nob) in the activated sludge was 15.7% +/- 3.7% and 12.9% +/- 3.2%, nitrosomonas e ...200919775004
[characteristics of n forms and n-transforming bacteria in paddy soil under different tillage patterns].paddy soil samples were collected in layers (0-5, 5-12, and 12-20 cm) during rice growth period to investigate the characteristics of the n forms and n-transforming bacteria in the soil profile under different tillage patterns (no-tillage with straw returning, nts; conventional tillage with straw returning, cts; no-tillage, nt; and conventional tillage, ct). in the whole rice growth period, ammonifying bacteria in 0-5 cm soil layer had the highest number under nts, and nitrosobacteria in 0-5 cm ...200919795645
shifts between nitrospira- and nitrobacter-like nitrite oxidizers underlie the response of soil potential nitrite oxidation to changes in tillage practices.despite their role in soil functioning, the ecology of nitrite-oxidizing bacteria, nob, and their response to disturbances such as those generated by agricultural practices are scarcely known. over the course of 17 months, we surveyed the potential nitrite oxidation, pno, the abundance of the nitrobacter- and nitrospira-like nob (by quantitative pcr) and the community structure of the nitrobacter-like nob (by pcr-dgge and cloning-sequencing targeting the nxra gene) in soils for four treatments: ...201019807778
the presence of an endogenous respiration in the autotrophic is shown that there exists in the autotrophic bacterium thiobacillus thiooxidans a measurable oxygen uptake in the absence of the specific nutrient (sulfur). this respiration is shown to be due to the utilization of organic materials which must have been previously synthesized by the chemosynthetic process, providing evidence that autotrophic bacteria contain a dissimilatory process which involves the breakdown of organic materials and furnishes energy for the maintenance of the cell during p ...194219873300
nitrifying microorganisms in fixed-bed biofilm reactors fed with different nitrite and ammonia concentrations.nitrifying bacteria and archaea were fed in fixed-bed biofilm reactors with different nitrite and ammonia concentrations in synthetic and real wastewater. during high nitrite concentrations (rho(no(2)(-))=5-10mg/l), an increase in the abundance of nitrobacter species was detected with fluorescence in situ hybridization (fish), while nitrospira species disappeared to a large extent. during high ammonia concentrations (rho(nh(4)(+))=60-80 mg/l), a slight increase in ammonia-oxidizing bacteria was ...201019910189
population dynamics of nitrite oxidizers in nitrifying granules.the competition between nitrospira and nitrobacter species was analyzed in this work under conditions of excess of nitrite. a population of nitrite oxidizing bacteria (nob) was developed from nitrifying biomass grown as granules with a mean diameter of 0.8 mm, whose feed was switched from ammonium to nitrite. the initial population distribution of the granules was: 60% nitrosomonas and 30% nitrospira and it evolved to 45% nitrobacter and 40% nitrospira measured 177 days after the change in the f ...200919923758
[effects of salinity variation on the treatment wastewater containing ammonia in the sbbr and sbr].according to nitrogen-containing wastewater, effects of salinity variation on nitrification and denitrification in internal circulation sequencing batch biofilm reactor (sbbr) and sequencing batch reactor (sbr), and the process of recovery as decreased salinity were investigated. the results show that nitrosation process is effected in internal circulation sbbr and sbr as the increase of salinity, and as the salinity is less than 1.0 x 10(4) mg x l(-1), the speed of ammonia-oxidize is quicker in ...200919927812
[efficiency analysis of two-stage sbr for phosphorus nitrogen and organic substrate removal].taking simulated domestic sewage as treatment object, the characteristics of separate-stage phosphorus, organic substrate and nitrogen removal were studied in two-stage sbr by contrast experiment and mechanism analysis under the normal temperature, its efficiency-predominance was analyzed. the results indicate that the heterotrophic paos and nitrobacteria can be dominant growth in individual reactor respectively, under the effluent quality is more superior, the treatment efficiency is one time h ...200919927813
operation of suspended-growth shortcut biological nitrogen removal (ssbnr) based on the minimum/maximum substrate concentration.this study exploited the concept of the minimum/maximum substrate concentrations (msc values) for identifying proper start-up conditions and achieving stable and low effluent total ammonium nitrogen (tan) concentrations in suspended-growth short-cut biological nitrogen removal (ssbnr). calculations based on the msc concept indicated that s(dmax), the tan concentration above which ammonium-oxidizing bacteria (aob) are washed out, was around 450mgtan/l at the given operating conditions of 2mg/l of ...201020004929
[nitrifying bacteria and nitrification in sediment at the adjacent sea area of yangtze river estuary in summer].the influence factors and environmental effects of nitrification process were discussed based on the measurements of nitrifier quantities and nitrification rates at eight sites off yangtze river estuary in june 2006. using fish (fluorescence in situ hybridization) method, the nitrifying bacteria were counted as 1.87 x 10(5) -3.53 x 10(5) cells/g wet weight and exhibited salt tolerance to some extent. the nitrification rates, measured by acetylene inhibition technique, ranged from 101.3 to 514.3 ...200920063730
nitrification in brackish water recirculating aquaculture system integrated with activated packed bed bioreactor.recirculation aquaculture systems (ras) depend on nitrifying biofilters for the maintenance of water quality, increased biosecurity and environmental sustainability. to satisfy these requirements a packed bed bioreactor (pbbr) activated with indigenous nitrifying bacterial consortia has been developed and commercialized for operation under different salinities for instant nitrification in shrimp and prawn hatchery systems. in the present study the nitrification efficiency of the bioreactor was t ...201020150717
limited impact of free ammonia on nitrobacter spp. inhibition assessed by chemical and molecular ammonia has long been identified as a nitrite oxidation inhibitor. however, past attempts to use this compound to eliminate nitrite oxidation and thereby promote more efficient nitrogen removal strategies during biological wastewater treatment have often failed. additionally, contradictory results exist in the literature where direct measurements of free ammonia inhibition of nitrite oxidation have been reported. in this study, suspended biomass samples (nitrifier enriched activated sludge) ...201020153631
nitrifier characteristics in submerged membrane bioreactors under different sludge retention times.three submerged membrane bioreactors (mbrs) were operated continuously for 230 days by feeding with synthetic inorganic wastewater (nh(4)(+)-n, 100 mg l(-1)) under different solids retention times (srts. m(30d), 30 days; m(90d), 90 days; m(infinite), no sludge purge) to examine the influence of srt on nitrification performance and microbial characteristics. all the reactors could oxidize nh(4)(+)-n to no(3)(-)-n effectively without accumulation of no(2)(-)-n. m(30d) with the shortest srt showed ...201020227741
microbial ecology and performance of nitrifying bacteria in an aerobic membrane bioreactor treating thin-film transistor liquid crystal display wastewater.this study was conducted to evaluate the long-term performance of an aerobic membrane bioreactor (mbr), treating tft-lcd wastewater containing dimethyl sulphoxide (dmso), monoethanolamine (mea) and tetra-methyl ammonium hydroxide (tmah), which are recognized as slow-biodegradable organic compounds containing nitrogen and can release significant amount of ammonia during biodegradation. moreover, many studies have reported that certain organic compounds can potentially inhibit nitrification of aob ...200819092215
[densification of autotrophic bacteria sludge and its characteristics for wastewater treatment].autotrophic granular sludge was developed in an sbr reactor using inorganic carbonal substrate. the variation of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nob) during the densification process and their effects on granulation have been evaluated. it was found that the autotrophic bacteria granular sludge was compact with the density reached up to 1.06 g/ml, and the rod-like bacteria predominated in granules on the evidence of scanning electron microscopic (sem) results. am ...201020358836
[cultivation of aerobic granules by a method of alternative feed loading].the formation process and morphological and physicochemical properties of aerobic granules were examined in a sbr system by a method of alternative feed loading. the results showed that the aerobic granules could be quickly and effectively cultivated using the alternative feeding cod 400, 800, 1200 mg/l [feed loading 0.96, 1.92 and 3.84 kg/(m3 x d)] when other conditions were fixed. the developed granules of the reactor were maintained in mlss 20-22 g/l and svi 14-16 ml/g. the average size of co ...201020358837
temporal variation in maximum cell-specific nitrification rate.the cell numbers of ammonia-oxidising bacteria (aobs), nitrospira and nitrobacter in activated sludge used to treat wastewater from a thermal power plant in japan were examined for nine months using a real-time pcr quantification technique. aob cell numbers ranged 2.8 x 10(10)-2.3 x 10(11) cell/l. the amoa clone analysis showed that the only nitrosomonas halophila was responsible for ammonia oxidation over the period. nitrospira were in the range of 2.6 x 10(9)-2.4 x 10(10) cell/l and nitrobacte ...201020389005
diversity of nitrifying bacteria in a full-scale petroleum refinery wastewater treatment plant experiencing unstable nitrification.we have investigated bacterial populations relevant to nitrification in a full-scale activated sludge plant receiving wastewater from a petroleum refinery showing unstable nitrification. inhibition of ammonia oxidation was related to phenol concentration according to a model of non-competitive inhibition. while the number of ammonia-oxidizing bacteria (aob) did not correlate with nitrification performance, the total number of nitrite-oxidizing bacteria (nob) dropped considerably during periods o ...201020570044
[analysis of microbial diversity of nitrifying bacteria by terminal restriction fragment length polymorphism].we analyzed the microbial diversity and quantity of nitrifying bacteria in the enrichment reactor by terminal restriction fragment length polymorphism (t_rflp), a cultured-independent molecular technique. the result indicated that nitrobacteria enriched the best, and the diversity index decreased 62.80% compared with the initial data. nitrobacteria were predominant in the reactor. meanwhile, we studied the microbial diversity before and after adding nitrobacteria into shrimp ponds, and analyzed ...201020575436
influence of physicochemical and operational parameters on nitrobacter and nitrospira communities in an aerobic activated sludge understand how to optimize performance of a partially nitrifying plant, the dynamics of nitrospira and nitrobacter abundance were studied over a 1 year period using quantitative polymerase chain reaction (qpcr) and their relative contributions to nitrite oxidation assessed including the affects of temperature and dissolved oxygen (do). correlation coefficients linking shifts in the community composition of nitrite-oxidizing bacteria (nob) to operational or environmental variables indicated ni ...201020591463
the behavior of nitrifying sludge in presence of sulfur compounds using a floating biofilm reactor.the tolerance, kinetic and oxidizing capability of a nitrifying sludge exposed to different initial concentrations of sulfide (1.7 to 18mg/l) was evaluated in batch experiments. a nitrifying sludge fed with ammonium and thiosulfate and produced in steady state conditions was used as inoculum. sulfide induced a significant effect either on ammonium consumption rates or nitrite accumulation. in spite of the nitrifying kinetic was affected, the ammonium consumption efficiencies were close to 100%, ...201020620047
[response of soil nitrification characteristics in subtropical area to air-drying].populations and activities of nitrifier can be significantly influenced by air-drying. a 35-day incubation study was conducted to determine the effects of air-drying on nitrification potential of four acid subtropical soils after applying 0 and 150 mg x kg(-1) of ammonium bicarbonate. four soils, designated qr, qu, sr and su, derived from quaternary red earth and tertiary red sandstone, were collected from rice and upland field. the results indicated that, without ammonium input, the responses o ...201020623880
nitrifying bacterial growth inhibition in the presence of algae and cyanobacteria.nitrifying bacteria, cyanobacteria, and algae are important microorganisms in open pond wastewater treatment systems. nitrification involving the sequential oxidation of ammonia to nitrite and nitrate, mainly due to autotrophic nitrifying bacteria, is essential to biological nitrogen removal in wastewater and global nitrogen cycling. a continuous flow autotrophic bioreactor was initially designed for nitrifying bacterial growth only. in the presence of cyanobacteria and algae, we monitored both ...201020632370
bacterial response to a shock load of nanosilver in an activated sludge treatment system.the growing release of nanosilver into sewage systems has increased the concerns on the potential adverse impacts of silver nanoparticles (agnps) in wastewater treatment plants. the inhibitory effects of nanosilver on wastewater treatment and the response of activated sludge bacteria to the shock loading of agnps were evaluated in a modified ludzack-ettinger (mle) activated sludge treatment system. before shock-loading experiments, batch extant respirometric assays determined that at 1mg/l of to ...201020638703
[monitoring the stoichiometric relation of ammonium oxidation with the titrimetry of hydrogen ion variation].a set of automatically titrimetric system to monitor the hydrogen ion variation during biological wastewater treatment process in a batch bioreactor was developed, which consists of a batch bioreactor, data auto-acquisition and preservation unit, and titrant autodosing unit. the accuracy of measurement for the system was evaluated by measuring the stoichiometric ratio of hydrogen ion production amount to ammonium consumption amount of ammonium oxidation in an activated sludge system. the ratios ...201020825030
characteristics of nitrogen removal and microbial distribution by application of spent sulfidic caustic in pilot scale wastewater treatment plant.since spent sulfidic caustic (ssc) produced from petrochemical industry contains a high concentration of alkalinity and sulfide, it was expected that ssc could be used as an electron donor for autotrophic denitrification. to investigate the nitrogen removal performance, a pilot scale bardenpho process was operated. the total nitrogen removal efficiency increased as ssc dosage increased, and the highest efficiency was observed as 77.5% when ssc was injected into both anoxic tank (1) and (2). fish ...201020861561
complete genome and comparative analysis of the chemolithoautotrophic bacterium oligotropha carboxidovorans om5.oligotropha carboxidovorans om5 t. (dsm 1227, atcc 49405) is a chemolithoautotrophic bacterium capable of utilizing co (carbon monoxide) and fixing co2 (carbon dioxide). we previously published the draft genome of this organism and recently submitted the complete genome sequence to genbank.201020863402
response of nitrifying bacterial communities to the increased thiocyanate concentration in pre-denitrification process.changes in process performance and the nitrifying bacterial community associated with an increase of thiocyanate (scn-) loading were investigated in a pre-denitrification process treating industrial wastewater. the increased scn- loading led to the concentration of total nitrogen (tn) in the final effluent, but increasing the internal recycling ratio as an operation parameter from 2 to 5 resulted in a 21% increase in tn removal efficiency. in the aerobic reactor, we found that the nitrosomonas e ...201020933392
detection of a complementary couple of single-stranded dnas by use of a quartz crystal device for determination of bacteria.preliminary experiments were carried out for the dna detection targeting a complementary couple of single-stranded dnas originating from nitrobacter winogradskyi. the target dnas were detected successfully with a quartz crystal unit bearing probe dnas, based on the oscillation frequency decrease due to hybridization of the probe and target dnas.201021041116
effects of free cyanide on microbial communities and biological carbon and nitrogen removal performance in the industrial activated sludge process.the changes in process performance and microbial communities under free cyanide (cn(-)) were investigated in a lab-scale activated sludge process treating industrial wastewater. the performance of phenol degradation did not appear to be adversely affected by increases in cn(-) concentrations. in contrast, cn(-) was found to have an inhibitory effect on scn(-) biodegradation, resulting in the increase of toc and cod concentrations. nitratation also appeared to be inhibited at cn(-) concentrations ...201021047665
seasonal variations of nitrifying community in trickling filter-solids contact (tf/sc) activated sludge systems.two full-scale trickling filter/solids contact (tf/sc) basin plants, each successfully performing nitrification, were sampled throughout various seasons over a period of one year. concentrations of ammonia, nitrate and nitrite were measured at various sampling locations along the treatment train. dna was also extracted from mixed liquor in the solids contact basins. these dna samples were subjected to terminal restriction fragment length polymorphism (trflp) in order to profile the ammonia oxidi ...201021112210
structure and dynamics of nitrifier populations in a full-scale submerged membrane bioreactor during start-up.changes of microbial characteristics in a full-scale submerged membrane bioreactor system (capacity, 60,000 m(3) day(-1)) treating sewage were monitored over the start-up period (96 days). fluorescence in situ hybridization analysis showed that the percentages of ammonia-oxidizing bacteria (aob) and nitrite-oxidizing bacteria (nitrobacter-related population) in total bacteria counted with dapi staining increased significantly from 1.9% and 0.9% to 4.5% and 2.8%, corresponding to an increase of t ...201021181155
cultivation, growth physiology, and chemotaxonomy of nitrite-oxidizing bacteria.lithoautotrophic nitrite-oxidizing bacteria (nob) are known as fastidious microorganisms, which are hard to maintain and not many groups are trained to keep them in culture. they convert nitrite stoichiometrically to nitrate and growth is slow due to the poor energy balance. nob are comprised of five genera, which are scattered among the phylogenetic tree. because nob proliferate in a broad range of environmental conditions (terrestrial, marine, acidic) and have diverse lifestyles (lithoautotrop ...201121185433
measurement and distribution of nitrification rates in the oceans.nitrification is the process that converts ammonium to nitrate and thus links the regeneration of organic nitrogen to fixed nitrogen loss by denitrification. the first step, oxidation of ammonia to nitrite, is performed by a phylogenetically restricted group of proteobacteria (ammonia-oxidizing bacteria, aob) and crenarchaea (ammonia-oxidizing archaea, aoa). the second step is restricted to nitrite-oxidizing bacteria (nob) as far as currently known. all three groups are assumed to be autotrophic ...201121185441
regulation and measurement of nitrification in terrestrial systems.understanding nitrification rates and their regulation continues as a key area of research for assessing human's increasing impact on the terrestrial n cycle. we review the organisms and processes responsible for nitrification in terrestrial systems. the control of nitrification by substrate availability is discussed with particular attention to the factors affecting ammonia/ammonium availability. the effects on nitrification rates of environmental controls including oxygen, water potential, tem ...201121185443
[achieving the stability of nitrosation under low do concentration].with a/o phosphorus removal process of secondary effluent as raw water, the stable accumulation of nitrite was achieved under low do. total nitrogen loss, hydraulic retention time (hrt) and sludge recycle ratio(r) was separately studied on the effects of stable nitrosation. according the result, apparent nitrosation rate was affected by the concentration of cod influence, when cod < or = 50 mg/l, apparent nitrosation rate was reduced; when cod > 50 mg/l, it was increased. extension and shortenin ...201021229747
[bioaugmentation for shortcut nitrification in sbr treating for sewage containing sea water by nitrification-aerobic denitrification bacteria].the feasibility of heterotrophic nitrification-aerobic denitrification bacteria applied in shortcut nitrification system was studied. four heterotrophic nitrification-aerobic denitrification strains mixed with halotolerant activated sludge was added into sbr in order to test their bioaugmentation ability for shortcut nitrification system, which was treating for sewage containing sea water, and the difference between bioaugmentation system and original system was compared. the results showed that ...201021229749
[influence of land-use type on moisture-effect of nitrification in subtropical red soils].air-drying is always accompanied by soil moisture loss. the different influences of air-drying on soil nitrification might due to the different nitrification responses to moisture changing of acid subtropical soils. so, after applying 0 and 150 mg x kg(-1) of ammonium bicarbonate, a 35-day incubation study was conducted to determine the nitrification potential of four acid subtropical soils under 5 soil moisture levels, namely 30% water-holding capacity (whc), 45% whc, 60% whc, 75% whc and 90% w ...201021229755
autotrophic growth of nitrifying community in an agricultural soil.the two-step nitrification process is an integral part of the global nitrogen cycle, and it is accomplished by distinctly different nitrifiers. by combining dna-based stable isotope probing (sip) and high-throughput pyrosequencing, we present the molecular evidence for autotrophic growth of ammonia-oxidizing bacteria (aob), ammonia-oxidizing archaea (aoa) and nitrite-oxidizing bacteria (nob) in agricultural soil upon ammonium fertilization. time-course incubation of sip microcosms indicated that ...201121326337
[studies on nitrobacteria and nitrification in liaohe estuary wetland sediments].nitrobacteria, nitrification and its impact factors were discussed based on the method of on-site incubation and laboratory simulation in liaohe estuary wetland sediments in june and august 2009, respectively. the results showed that the number of ammonia-oxidizing bacteria (aob) ranged from 0.54 x 10(4) to 5.69 x 10(4) cells x g(-1) with an average of (2.21 +/- 2.32) x 10(4) cells x g(-1) in june and ranged from 1.90 x 10(4) to 7.90 x 10(4) cells x g(-1) with an average of (3.61 +/- 2.87) x 10( ...201021360893
unexpected diversity of chlorite dismutases: a catalytically efficient dimeric enzyme from nitrobacter winogradskyi.chlorite dismutase (cld) is a unique heme enzyme catalyzing the conversion of clo(2)(-) to cl(-) and o(2). cld is usually found in perchlorate- or chlorate-reducing bacteria but was also recently identified in a nitrite-oxidizing bacterium of the genus nitrospira. here we characterized a novel cld-like protein from the chemolithoautotrophic nitrite oxidizer nitrobacter winogradskyi which is significantly smaller than all previously known chlorite dismutases. its three-dimensional (3d) crystal st ...201121441524
nitrifying bacterial community structure of a full-scale integrated fixed-film activated sludge process as investigated by pyrosequencing.nitrifying bacterial community structures of suspended and attached biomasses in a full-scale integrated fixed-film activated sludge process were investigated by analyzing 16s rrna gene sequences obtained from pyrosequencing. the suspended biomass had a higher number of ammoniaoxidizing bacterial sequences (0.8% of total sequences) than the attached biomass (0.07%), although most of the sequences were within the nitrosomonas oligotropha lineage in both biomasses. nitrospira-like nitrite-oxidizin ...201121464601
structure of nitrifying biofilms in a high-rate trickling filter designed for potable water pre-treatment.this study examined the composition and structure of nitrifying biofilms sampled from a high-rate nitrifying trickling filter which was designed to pre-treat raw surface water for potable supply. the filter was operated under a range of feed water ammonia and organic carbon concentrations that mimicked the raw water quality of poorly protected catchments. the biofilm structure was examined using a combination of fluorescence in situ hybridisation and scanning electron microscopy. biopolymers (ca ...201121543100
microbial population dynamics and community structure during the formation of nitrifying granules to treat ammonia-rich inorganic wastewater.microbial population dynamics were investigated during the formation of nitrifying granules in an aerobic upflow fluidized bed (aufb) reactor fed ammonia as a sole energy source. analyses of clone libraries of 16s rrna gene and the ammonia monooxygenase subunit a gene (amoa) revealed that although the clones obtained from the seed sludge were widely distributed among the ammonia-oxidizing bacteria (aob) isolates, the community structure of aob shifted towards the nitrosomonas mobilis lineage as ...201021576869
comparison of conventional and integrated fixed-film activated sludge systems: attached- and suspended-growth functions and quantitative polymerase chain reaction measurements.pilot-scale integrated fixed-film activated sludge (ifas) and non-ifas control systems were compared, with respect to overall performance and functional behaviors and microbial population composition in the attached and suspended phases. the suspended phases of the control and ifas systems exhibited similar rates of ammonia consumption; the attached phase in the second aerobic ifas reactor had significantly higher rates of ammonia consumption and nitrate production than any other biomass source, ...201121790081
effect of ph and nitrite concentration on nitrite oxidation rate.the effect of ph and nitrite concentration on the activity of the nitrite oxidizing bacteria (nob) in an activated sludge reactor has been determined by means of laboratory batch experiments based on respirometric techniques. the bacterial activity was measured at different ph and at different total nitrite concentrations (tno(2)). the experimental results showed that the nitrite oxidation rate (nor) depends on the tno(2) concentration independently of the free nitrous acid (fna) concentration, ...201121843934
free nitrous acid selectively inhibits and eliminates nitrite oxidizers from nitrifying sequencing batch a complete nitrification sequencing batch reactor (cnsbr), where ammonium containing wastewater (200-1,000 mg n/l) is completely oxidized to nitrate up to 2.4 kg nh(4) (+)-n/m(3) d, both ammonia oxidizers and nitrite oxidizers were enriched in the sludge granules. quantitative fluorescence in situ hybridization analyses of the sludge granules of the cnsbr showed that ammonia oxidizers and nitrite oxidizers occupied 31 and 4.2% of total bacteria, respectively. most of the nitrite oxidizers wer ...201121874514
Influence of growth manner on nitrifying bacterial communities and nitrification kinetics in three lab-scale bioreactors.The effects of growth type, including attached growth, suspended growth, and combined growth, on the characteristics of communities of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were studied in three lab-scale Anaerobic/Anoxic(m)-Oxic(n) (AmOn) systems. These systems amplified activated sludge, biofilms, and a mixture of activated sludge and biofilm (AS-BF). Identical inocula were adopted to analyze the selective effects of mixed growth patterns on nitrifying bacteria. ...201122160273
Protozoan predation on nitrification performance and microbial community during bioaugmentation.The effects of predation on nitrification performance and microbial community during bioaugmentation were investigated. Although most of the nitrification ability of the seed source was lost in the seeded reactors, bioaugmentation significantly enhanced the activity and community of the nitrifiers. The ammonium uptake rate (AUR) increased from 2.59 to 15.25 mg NH4+-N/Lh and 2.88 to 13.36 mg NH4+-N/Lh, and the nitrite uptake rate (NUR) increased from 0.80 to 4.02 mg NO2--N/Lh and 0.76 to 4.34 mg ...201121983411
Influence of operational parameters on nitrogen removal efficiency and microbial communities in a full-scale activated sludge process.To improve the efficiency of total nitrogen (TN) removal, solid retention time (SRT) and internal recycling ratio controls were selected as operating parameters in a full-scale activated sludge process treating high strength industrial wastewater. Increased biomass concentration via SRT control enhanced TN removal. Also, decreasing the internal recycling ratio restored the nitrification process, which had been inhibited by phenol shock loading. Therefore, physiological alteration of the bacteria ...201121924454
Effects of long-term fertilization of forest soils on potential nitrification and on the abundance and community structure of ammonia oxidizers and nitrite oxidizers.Forest fertilization in British Columbia is increasing, to alleviate timber shortfalls resulting from the mountain pine beetle epidemic. However, fertilization effects on soil microbial communities, and consequently ecosystem processes, are poorly understood. Fertilization has contrasting effects on ammonia-oxidizing bacteria and archaea (AOB and AOA) in grassland and agricultural ecosystems, but there are no studies on AOB and AOA in forests. We assessed the effect of periodic (6-yearly applica ...201122066501
fate of nitrogen-fixing bacteria in crude oil contaminated wetland ultisol.the effect of crude oil on the growth of legumes (calopogonium muconoides and centrosema pubescens) and fate of nitrogen-fixing bacteria in wetland ultisol was investigated using standard cultural techniques. the results revealed observable effects of oil on soil physico-chemistry, plant growth and nodulation as well as on densities of heterotrophic, hydrocarbonoclastic and nitrogen fixing bacteria. the effects however varied with different levels (0.5%, 1%, 5%, 10%, 15% and 20%) of pollution. a ...201121755289
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