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1.
Allergol Int ; 73(2): 224-230, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38065704

RESUMEN

BACKGROUND: Maintaining good asthma control minimizes the risk of exacerbations and lung function decline and is a primary goal of asthma management. The Japanese Pediatric Asthma Guidelines (JPGL) employs different classification criteria for control status from other guidelines, stressing a higher level of control. Based on JPGL, we previously developed a caregiver-completed questionnaire for assessing and achieving best asthma control in preschoolers. In this study, we aimed to develop a questionnaire for school-age children and adolescents. METHODS: A working questionnaire comprising 14 items for patients and 34 items for caregivers was administered to 362 asthma patients aged 6-15 years and their caregivers. Separately, physicians filled out a questionnaire to determine JPGL-defined control. Logistic regression analysis was performed to construct a model to predict control levels using data from a randomly selected set of completed questionnaires from two-thirds of the subjects. Validation was performed using the remaining questionnaires. RESULTS: A set of 7 questions, encompassing self-assessed control status at the time of the visit and in the past month, and nocturnal/early morning asthma symptoms for patients and frequency of asthma symptoms, dyspnea, rescue beta-agonist use, and asthma hospitalization for caregivers, were selected and the 7-item model showed a good statistical fit with AIC of 110.5. The model has been named the Best Asthma Control Test for School Children and Adolescents (Best ACT-S). Best ACT-S scores differed significantly in the hypothetical direction among the groups of different JPGL-defined control levels, step-up/down treatment decisions, and presence/non-presence of exacerbations in the previous year. CONCLUSIONS: The Best ACT-S is a valid questionnaire for children/adolescents aiming for best asthma control.


Asunto(s)
Asma , Niño , Humanos , Adolescente , Asma/diagnóstico , Asma/epidemiología , Asma/terapia , Disnea , Encuestas y Cuestionarios , Cuidadores , Hospitalización
2.
Environ Sci Technol ; 57(37): 13874-13886, 2023 09 19.
Artículo en Inglés | MEDLINE | ID: mdl-37676844

RESUMEN

A transition to ammonia recovery from wastewater has started; however, a technology for sustainable nitrogen retention in the form of ammonia and organic carbon removal is still in development. This study validated a microaerophilic activated sludge (MAS) system to efficiently retain ammonia from high-strength nitrogenous wastewater. The MAS is based on conventional activated sludge (CAS) with aerobic and settling compartments. Low dissolved oxygen (DO) concentrations (<0.2 mg/L) and short solids retention times (SRTs) (<5 days) eliminated nitrifying bacteria. The two parallel MASs were successfully operated for 300 days and had ammonia retention of 101.7 ± 24.9% and organic carbon removal of 85.5 ± 8.9%. The MASs mitigated N2O emissions with an emission factor of <0.23%, much lower than the default value of CAS (1.6%). A short-term step-change test demonstrated that N2O indicated the initiation of nitrification and the completion of denitrification in the MAS. The parallel MASs had comparable microbial diversity, promoting organic carbon oxidation while inhibiting ammonia-oxidizing microorganisms (AOMs), as revealed by 16S rRNA gene amplicon sequencing, the quantitative polymerase chain reaction of functional genes, and fluorescence in situ hybridization of ß-proteobacteria AOB. The microbial analyses also uncovered that filamentous bacteria were positively correlated with effluent turbidity. Together, controlling DO and SRT achieved organic carbon removal and successful ammonia retention, mainly by suppressing AOM activity. This process represents a new nitrogen management paradigm.


Asunto(s)
Microbiota , Aguas del Alcantarillado , Aguas Residuales , Amoníaco , Hibridación Fluorescente in Situ , ARN Ribosómico 16S , Carbono , Nitrógeno
3.
Environ Res ; 219: 115175, 2023 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-36584848

RESUMEN

Lacustrine eutrophication is generally considered as an important contributor of carbon emissions to the atmosphere; however, there is still a huge challenge in accuracy estimating carbon emissions from lakes. To test the effect of widely used space-for-time substitution on lake carbon emissions, this study monitored different processes of carbon emissions, including the carbon production potential, dissolved carbon concentrations, and carbon release fluxes in eight lakes along the trophic gradients on a spatial scale and the typical eutrophic Lake Taihu for one year on a temporal scale. Eutrophication promoted carbon production potential, dissolved carbon concentrations, and carbon release fluxes, especially for CH4. Trophic lake index (TLI) showed positive correlations with the CH4 production potential, dissolved CH4 concentrations, and CH4 release fluxes, and also positive correlations with the CO2 production potential, dissolved CO2 concentrations, and CO2 release fluxes. The space-for-time substitution led to an overestimation for the influence of eutrophication on carbon emissions, especially the further intensification of lake eutrophication. On the spatial scale, the average CH4 production potential, dissolved CH4 concentrations and CH4 release fluxes in eutrophic lakes were 268.6, 0.96 µmol/L, and 587.6 µmol m-2·h-1, respectively, while they were 215.8, 0.79 µmol/L, and 548.6 µmol m-2·h-1 on the temporal scale. Obviously, CH4 and CO2 emissions on the spatial scale were significantly higher than those on the temporal scale in eutrophic lakes. The primary influencing factors were the seasonal changes in the physicochemical environments of lake water, including dissolved oxygen (DO) and temperature. The CH4 and CO2 release fluxes showed negative correlations with DO, while temperature displayed positive correlations, respectively. These results suggest that the effects of DO and temperature on lake carbon emissions should be considered, which may be ignored during the accurate assessment of lake carbon budget via space-for-time substitution in eutrophic lakes.


Asunto(s)
Carbono , Lagos , Dióxido de Carbono/análisis , Metano/análisis , Temperatura , China
4.
Arerugi ; 72(9): 1138-1146, 2023.
Artículo en Japonés | MEDLINE | ID: mdl-37967960

RESUMEN

BACKGROUND: Little is known whether sublingual immunotherapy using Japanese cedar pollen extract (cedar SLIT) is effective for not only Japanese cedar pollinosis but also Japanese cypress pollinosis. We investigated the prevalence rate of Japanese cypress pollinosis, efficacy of cedar SLIT on cypress pollinosis and patients' wish to receive cypress SLIT. METHODS: We investigated a multi-center (31 institutions), cross-sectional survey using a self-administrated questionnaire with four questions for patients received cedar SLIT aged from 5 to 69 years old. RESULTS: 2523 subjects were enrolled for analysis. 83.4% of them had pollinosis symptoms during cypress season before cedar SLIT. In such patients, 37.4% experienced lessened efficacy of cedar SLIT during cypress season. Both the prevalence of cypress pollinosis and the lessened efficacy of cedar SLIT on cypress pollinosis were significantly seen in western Japan as compared to eastern Japan. 76.1% of the subject having cypress pollinosis before SLIT wished to receive cypress SLIT if it is available. CONCLUSION: A lessened efficacy of cedar SLIT during cypress season was broadly seen in Japan, and further showed a regional difference. Together with the finding of high wish by patients, these results suggest a development of cypress SLIT is desirable.


Asunto(s)
Cryptomeria , Cupressus , Rinitis Alérgica Estacional , Inmunoterapia Sublingual , Humanos , Preescolar , Niño , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad , Anciano , Rinitis Alérgica Estacional/terapia , Rinitis Alérgica Estacional/tratamiento farmacológico , Polen , Estudios Transversales , Prevalencia , Encuestas y Cuestionarios , Alérgenos
5.
Environ Sci Technol ; 56(16): 11694-11706, 2022 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-35917165

RESUMEN

In denitrifying reactors, canonical complete denitrifying bacteria reduce nitrate (NO3-) to nitrogen via N2O. However, they can also produce N2O under certain conditions. We used a 15N tracer method, in which 15N-labeled NO3-/nitrite (NO2-) and nonlabeled N2O were simultaneously supplied with organic electron donors to five canonical complete denitrifying bacteria affiliated with either Clade I or Clade II nosZ. We calculated their NO3-, NO2-, and N2O consumption rates. The Clade II nosZ bacterium Azospira sp. strain I13 had the highest N2O consumption rate (3.47 ± 0.07 fmol/cell/h) and the second lowest NO3- consumption rate (0.20 ± 0.03 fmol/cell/h); hence, it is a N2O sink. A change from peptone- to acetate/citrate-based organic electron donors increased the NO3- consumption rate by 4.8 fold but barely affected the N2O consumption rate. Electron flow was directed to N2O rather than NO3- in Azospira sp. strain I13 and Az. oryzae strain PS only exerting a N2O sink but to NO3- in the Clade I nosZ N2O-reducing bacteria Pseudomonas stutzeri strain JCM 5965 and Alicycliphilus denitrificans strain I51. Transcriptome analyses revealed that the genotype could not fully describe the phenotype. The results show that N2O production and consumption differ among canonical denitrifying bacteria and will be useful for developing N2O mitigation strategies.


Asunto(s)
Dióxido de Nitrógeno , Óxido Nitroso , Bacterias , Desnitrificación , Perfilación de la Expresión Génica , Nitritos
6.
Biotechnol Bioeng ; 118(3): 1330-1341, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33305820

RESUMEN

Nitrous oxide (N2 O), a potent greenhouse gas, is reduced to N2 gas by N2 O-reducing bacteria (N2 ORB), a process which represents an N2 O sink in natural and engineered ecosystems. The N2 O sink activity by N2 ORB depends on temperature and O2 exposure, yet the specifics are not yet understood. This study explores the effects of temperature and oxygen exposure on biokinetics of pure culture N2 ORB. Four N2 ORB, representing either clade I type nosZ (Pseudomonas stutzeri JCM5965 and Paracoccus denitrificans NBRC102528) or clade II type nosZ (Azospira sp. strains I09 and I13), were individually tested. The higher activation energy for N2 O by Azospira sp. strain I13 (114.0 ± 22.6 kJ mol-1 ) compared with the other tested N2 ORB (38.3-60.1 kJ mol-1 ) indicates that N2 ORB can adapt to different temperatures. The O2 inhibition constants (KI ) of Azospira sp. strain I09 and Ps. stutzeri JCM5965 increased from 0.06 ± 0.05 and 0.05 ± 0.02 µmol L-1 to 0.92 ± 0.24 and 0.84 ± 0.31 µmol L-1 , respectively, as the temperature increased from 15°C to 35°C, while that of Azospira sp. strain I13 was temperature-independent (p = 0.106). Within the range of temperatures examined, Azospira sp. strain I13 had a faster recovery after O2 exposure compared with Azospira sp. strain I09 and Ps. stutzeri JCM5965 (p < 0.05). These results suggest that temperature and O2 exposure result in the growth of ecophysiologically distinct N2 ORB as N2 O sinks. This knowledge can help develop a suitable N2 O mitigation strategy according to the physiologies of the predominant N2 ORB.


Asunto(s)
Óxido Nitroso/metabolismo , Paracoccus denitrificans/metabolismo , Pseudomonas stutzeri/metabolismo , Rhodocyclaceae/metabolismo , Temperatura
7.
Environ Sci Technol ; 55(13): 9231-9242, 2021 07 06.
Artículo en Inglés | MEDLINE | ID: mdl-34142798

RESUMEN

Although nitrogen removal by partial nitritation and anammox is more cost-effective than conventional nitrification and denitrification, one downside is the production and accumulation of nitrous oxide (N2O). The potential exploitation of N2O-reducing bacteria, which are resident members of anammox microbial communities, for N2O mitigation would require more knowledge of their ecophysiology. This study investigated the phylogeny of resident N2O-reducing bacteria in an anammox microbial community and quantified individually the processes of N2O production and N2O consumption. An up-flow column-bed anammox reactor, fed with NH4+ and NO2- and devoid of oxygen, emitted N2O at an average conversion ratio (produced N2O: influent nitrogen) of 0.284%. Transcriptionally active and highly abundant nosZ genes in the reactor biomass belonged to the Burkholderiaceae (clade I type) and Chloroflexus genera (clade II type). Meanwhile, less abundant but actively transcribing nosZ strains were detected in the genera Rhodoferax, Azospirillum, Lautropia, and Bdellovibrio and likely act as an N2O sink. A novel 15N tracer method was adapted to individually quantify N2O production and N2O consumption rates. The estimated true N2O production rate and true N2O consumption rate were 3.98 ± 0.15 and 3.03 ± 0.18 mgN·gVSS-1·day-1, respectively. The N2O consumption rate could be increased by 51% (4.57 ± 0.51 mgN·gVSS-1·day-1) with elevated N2O concentrations but kept comparable irrespective of the presence or absence of NO2-. Collectively, the approach allowed the quantification of N2O-reducing activity and the identification of transcriptionally active N2O reducers that may constitute as an N2O sink in anammox-based processes.


Asunto(s)
Reactores Biológicos , Desnitrificación , Nitrificación , Nitrógeno , Óxido Nitroso , Oxidación-Reducción
8.
Environ Sci Technol ; 53(20): 12101-12112, 2019 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-31517481

RESUMEN

The recent discovery of nitrous oxide (N2O)-reducing bacteria suggests a potential biological sink for the potent greenhouse gas N2O. For an application toward N2O mitigation, characterization of more isolates will be required. Here, we describe the successful enrichment and isolation of high-affinity N2O-reducing bacteria using a N2O-fed reactor (N2OFR). Two N2OFRs, where N2O was continuously and directly supplied as the sole electron acceptor to a biofilm grown on a gas-permeable membrane, were operated with acetate or a mixture of peptone-based organic substrates as an electron donor. In parallel, a NO3- -fed reactor (NO3FR), filled with a nonwoven sheet substratum, was operated using the same inoculum. We hypothesized that supplying N2O vs NO3- would enhance the dominance of distinct N2O-reducing bacteria. Clade II type nosZ bacteria became rapidly enriched over clade I type nosZ bacteria in the N2OFRs, whereas the opposite held in the NO3FR. High-throughput sequencing of 16S rRNA gene amplicons revealed the dominance of Rhodocyclaceae in the N2OFRs. Strains of the Azospira and Dechloromonas genera, canonical denitrifiers harboring clade II type nosZ, were isolated with high frequency from the N2OFRs (132 out of 152 isolates). The isolates from the N2OFR demonstrated higher N2O uptake rates (Vmax: 4.23 × 10-3-1.80 × 10-2 pmol/h/cell) and lower N2O half-saturation coefficients (Km,N2O: 1.55-2.10 µM) than a clade I type nosZ isolate from the NO3FR. Furthermore, the clade II type nosZ isolates had higher specific growth rates on N2O than nitrite as an electron acceptor. Hence, continuously and exclusively supplying N2O in an N2OFR allows the enrichment and isolation of high-affinity N2O-reducing strains, which may be used as N2O sinks in bioaugmentation efforts.


Asunto(s)
Bacterias , Óxido Nitroso , Biopelículas , Desnitrificación , ARN Ribosómico 16S , Rhodocyclaceae
9.
Appl Microbiol Biotechnol ; 102(22): 9815-9829, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30203144

RESUMEN

This paper discusses the microbial basis and the latest research on nitrous oxide (N2O) emissions from biofilms processes for wastewater treatment. Conditions that generally promote N2O formation in biofilms include (1) low DO values, or spatial DO transitions from high to low within the biofilm; (2) DO fluctuations within biofilm due to varying bulk DO concentrations or varying substrate concentrations; (3) conditions with high reaction rates, which lead to greater formation of intermediates, e.g., hydroxylamine (NH2OH) and nitrite (NO2-), that promote N2O formation; and (4) electron donor limitation for denitrification. Formation of N2O directly results from the activities of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and heterotrophic denitrifying bacteria. More research is needed on the roles of AOA, comammox, and specialized denitrifying microorganisms. In nitrifying biofilms, higher bulk ammonia (NH3) concentrations, higher nitrite (NO2-) concentrations, lower dissolved oxygen (DO), and greater biofilm thicknesses result in higher N2O emissions. In denitrifying biofilms, N2O accumulates at low levels as an intermediate and at higher levels at the oxic/anoxic transition regions of the biofilms and where COD becomes limiting. N2O formed in the outer regions can be consumed in the inner regions if COD penetrates sufficiently. In membrane-aerated biofilms, where nitrification takes place in the inner, aerobic biofilm region, the exterior anoxic biofilm can serve as a N2O sink. Reactors that include variable aeration or air scouring, such as denitrifying filters, trickling filters, or rotating biological contactors (RBCs), can form peaks of N2O emissions during or following a scouring or aeration event. N2O emissions from biofilm processes depend on the microbial composition, biofilm thickness, substrate concentrations and variability, and reactor type and operation. Given the complexity and difficulty in quantifying many of these factors, it may be difficult to accurately predict emissions for full-scale treatment plants. However, a better understanding of the mechanisms and the impacts of process configurations can help minimize N2O emission from biofilm processes for wastewater treatment.


Asunto(s)
Archaea/metabolismo , Bacterias/metabolismo , Óxido Nitroso/análisis , Aguas Residuales/microbiología , Amoníaco/metabolismo , Archaea/clasificación , Archaea/genética , Archaea/aislamiento & purificación , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Biopelículas , Reactores Biológicos/microbiología , Desnitrificación , Procesos Heterotróficos , Nitrificación , Nitritos/metabolismo , Óxido Nitroso/metabolismo , Oxígeno/análisis , Oxígeno/metabolismo , Aguas Residuales/análisis
10.
Appl Microbiol Biotechnol ; 102(3): 1501-1512, 2018 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-29204898

RESUMEN

The goal of this study was to develop a startup strategy for a high-rate anaerobic ammonium oxidation (anammox) reactor to treat waste brine with high concentrations of ammonium from a natural gas plant. An upflow anaerobic sludge blanket (UASB) anammox reactor with an effective volume of 294 L was fed continuously with waste brine with a salinity of 3% and a NH4+ concentration of 180 mg-N/L, as well as a NaNO2 solution. By inoculating a methanogenic granular biomass as a biomass carrier, the reactor attained the maximum volumetric nitrogen removal rate (NRR) of 10.7 kg-N/m3/day on day 209, which was 1.7 times higher than the highest reported NRR for wastewater of comparable salinity. High-throughput sequencing of 16S rRNA gene amplicons revealed that Candidatus Scalindua wagneri was enriched successfully in granules in the UASB, and it replaced Methanosaeta and became dominant in the granule. The inhibitory effect of NO2- on the anammox reaction in the granules was assessed by a 15N tracer method, and the results showed that anammox activity was maintained at 60% after exposure to 300 mg-N/L of NO2- for 24 h. Compared with previous studies of the susceptibilities of Candidatus Brocadia and Candidatus Kuenenia to NO2-, the enriched marine anammox bacteria were proven to have comparable or even higher tolerances for high NO2- concentrations after a long exposure.


Asunto(s)
Compuestos de Amonio/metabolismo , Bacterias/metabolismo , Reactores Biológicos/microbiología , Desnitrificación , Nitrógeno/metabolismo , Aguas del Alcantarillado/microbiología , Anaerobiosis , Biomasa , Oxidación-Reducción , Proyectos Piloto , Sales (Química)/química , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/microbiología , Purificación del Agua/métodos
11.
Ecotoxicol Environ Saf ; 147: 72-79, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28837872

RESUMEN

Leaching of hazardous trace elements from excavated urban soils during construction of cities has received considerable attention in recent years in Japan. A new concept, the pollution potential leaching index (PPLI), was applied to assess the risk of arsenic (As) leaching from excavated soils. Sequential leaching tests (SLT) with two liquid-to-solid (L/S) ratios (10 and 20Lkg-1) were conducted to determine the PPLI values, which represent the critical cumulative L/S ratios at which the average As concentrations in the cumulative leachates are reduced to critical values (10 or 5µgL-1). Two models (a logarithmic function model and an empirical two-site first-order leaching model) were compared to estimate the PPLI values. The fractionations of As before and after SLT were extracted according to a five-step sequential extraction procedure. Ten alkaline excavated soils were obtained from different construction projects in Japan. Although their total As contents were low (from 6.75 to 79.4mgkg-1), the As leaching was not negligible. Different L/S ratios at each step of the SLT had little influence on the cumulative As release or PPLI values. Experimentally determined PPLI values were in agreement with those from model estimations. A five-step SLT with an L/S of 10Lkg-1 at each step, combined with a logarithmic function fitting was suggested for the easy estimation of PPLI. Results of the sequential extraction procedure showed that large portions of more labile As fractions (non-specifically and specifically sorbed fractions) were removed during long-term leaching and so were small, but non-negligible, portions of strongly bound As fractions.


Asunto(s)
Arsénico/análisis , Modelos Teóricos , Contaminantes del Suelo/análisis , Suelo/química , Urbanización , Contaminantes Químicos del Agua/análisis , Fraccionamiento Químico , Industria de la Construcción , Japón
12.
J Environ Manage ; 217: 297-304, 2018 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-29614478

RESUMEN

Excavated soils with low-level As contamination obtained from construction projects during city development have been of great concern in Japan. Water-extractable As represents the most easily mobilized and ecotoxicologically relevant fraction in the soil environment. In the present study, the water-extractability of As in excavated alkaline urban soils was assessed using sequential leaching tests (SLTs) with a focus on the effects of test parameters. In addition, the potentially water-leachable As over an extremely long period was assessed using the pollution potential leaching index (PPLI), from which one can estimate the number of extractions required to reduce the As in the cumulative leachates to below the Japanese environmental standard (10 µg L-1). Total As concentrations varied from 6.75 to 79.4 mg kg-1, and As was continuously detectable among replicate SLT experiments. The water-extractable As obtained in the first step of the SLT accounted for 0.41%-7.60% of total As (average: 2.36%), while the cumulative released As in the SLTs corresponded to 1.30%-21.6% of the total (average: 10.6%). The variability of the water-soluble fractions was sensitive to the test conditions. The shaking time at each SLT step had the largest effect on the As water-extractability; followed by sample storage, shaking speed and shaking interruption. A longer shaking time in the standard leaching test of excavated soils is suggested for regulatory purposes in Japan. The use of the PPLI concept for quick estimation of the potential As leachability from excavated soils was supported by the good reproducibility of PPLI results obtained from SLTs under different test parameters.


Asunto(s)
Arsénico/química , Contaminantes del Suelo , Agua , Arsénico/aislamiento & purificación , Japón , Reproducibilidad de los Resultados , Suelo
13.
Environ Sci Technol ; 51(5): 2748-2756, 2017 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-28164698

RESUMEN

The goal of this study was to elucidate the mechanisms of nitrous oxide (N2O) production from a bioreactor for partial nitrification (PN). Ammonia-oxidizing bacteria (AOB) enriched from a sequencing batch reactor (SBR) were subjected to N2O production pathway tests. The N2O pathway test was initiated by supplying an inorganic medium to ensure an initial NH4+-N concentration of 160 mg-N/L, followed by 15NO2- (20 mg-N/L) and dual 15NH2OH (each 17 mg-N/L) spikings to quantify isotopologs of gaseous N2O (44N2O, 45N2O, and 46N2O). N2O production was boosted by 15NH2OH spiking, causing exponential increases in mRNA transcription levels of AOB functional genes encoding hydroxylamine oxidoreductase (haoA), nitrite reductase (nirK), and nitric oxide reductase (norB) genes. Predominant production of 45N2O among N2O isotopologs (46% of total produced N2O) indicated that coupling of 15NH2OH with 14NO2- produced N2O via N-nitrosation hybrid reaction as a predominant pathway. Abiotic hybrid N2O production was also observed in the absence of the AOB-enriched biomass, indicating multiple pathways for N2O production in a PN bioreactor. The additional N2O pathway test, where 15NH4+ was spiked into 400 mg-N/L of NO2- concentration, confirmed that the hybrid N2O production was a dominant pathway, accounting for approximately 51% of the total N2O production.


Asunto(s)
Nitritos/metabolismo , Óxido Nitroso/metabolismo , Amoníaco/metabolismo , Reactores Biológicos/microbiología , Hidroxilamina , Hidroxilaminas , Oxidación-Reducción
14.
Appl Microbiol Biotechnol ; 101(4): 1673-1683, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-27837317

RESUMEN

We investigated the effects of free ammonia (FA) and free nitrous acid (FNA) concentrations on the predominant ammonia-oxidizing bacteria (AOB) and the emission of nitrous oxide (N2O) in a lab-scale sequencing batch reactor for partial nitrification. The reactor was operated with stepwise increases in the NH4+ loading rate, which resulted in a maximum FA concentration of 29.3 mg-N/L at pH 8.3. Afterwards, FNA was increased by a gradual decrease of pH, reaching its maximum concentration of 4.1 mg-N/L at pH 6.3. Fluorescence in situ hybridization indicated that AOB remained predominant during the operation, achieving specific nitrification rates of 1.04 and 0.99 g-N/g-VSS/day at the highest accumulations of FA and FNA, respectively. These rates were in conjunction with partial nitrification efficiencies of >84%. The N2O emission factor of oxidized NH4+ was 0.90% at pH 7.0, which was higher than those at pH 8.3 (0.11%) and 6.3 (0.12%), the pHs with the maximum FA and FNA concentrations, respectively. High-throughput sequencing of 16S ribosomal RNA genes showed that increases in FNA drastically changed the predominant AOB species, although increased FA produced no significant changes. This study demonstrates that the FNA concentration and pH are the main drivers that determine the predominant AOB species and N2O-emission in a partial nitrifying bioreactor.


Asunto(s)
Amoníaco/metabolismo , Ácido Nitroso/metabolismo , Bacterias/metabolismo , Reactores Biológicos/microbiología , Concentración de Iones de Hidrógeno , Nitrificación , Óxido Nitroso/metabolismo
15.
Water Environ Res ; 89(7): 580-585, 2017 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-28641669

RESUMEN

This research used the detailed activated sludge model (ASM) to investigate the effect of parameter uncertainty on nitrous oxide (N2O) emissions from biological wastewater treatment systems. Monte Carlo simulations accounted for uncertainty in the values of the microbial growth parameters and in the volumetric mass transfer coefficient for dissolved oxygen (kLaDO), and the results show that the detailed ASM predicted N2O emission of less than 4% (typically 1%) of the total influent loading. Uncertainties in kLaDO were further investigated in experiments, which showed that lower values of kLaDO generated higher soluble N2O levels. The detailed ASM likely requires revision to account for abiotic reactions and other factors that cause higher levels of N2O emission.


Asunto(s)
Contaminantes Atmosféricos/química , Óxido Nitroso/química , Instalaciones de Eliminación de Residuos , Análisis de la Demanda Biológica de Oxígeno , Modelos Teóricos , Incertidumbre , Aguas Residuales/química , Purificación del Agua
16.
Water Sci Technol ; 75(1-2): 115-127, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28067652

RESUMEN

Anammox application for nutrient removal from wastewater is increasing, though questions remain about anammox resilience to fluctuating conditions. Resuscitation of anammox suspended- and attached-growth cultures after 3 months of starvation was studied with and without acetate dosing. Without acetate, the attached-growth culture recovered more quickly than the suspended-growth culture. Suspended-growth cultures recovered more quickly (within 60 days) with weekly and daily acetate dosing than without, but anammox activity and copy numbers decreased with continued acetate addition. All attached-growth cultures recovered within 60 days, but after that activity with acetate dosing was consistently at least 20% lower than that without acetate addition. Ca. Jettenia caeni, Ca. Anammoxoglobus sp., Ca. Brocadia fulgida, Ca. Brocadia anammoxidans, Ca. Brocadia fulgida and Ca. Jettenia asiatica were identified. Acetate addition can significantly accelerate short-term resuscitation of enriched anammox suspended-growth cultures after starvation but may reduce anammox activity over the longer term in suspended- and attached-growth cultures.


Asunto(s)
Acetatos/metabolismo , Compuestos de Amonio/química , Bacterias Anaerobias/fisiología , Oxidación-Reducción , Compuestos de Amonio Cuaternario , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/microbiología , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/metabolismo
17.
Pediatr Allergy Immunol ; 27(3): 307-12, 2016 05.
Artículo en Inglés | MEDLINE | ID: mdl-26659837

RESUMEN

BACKGROUND: Several patient-/caregiver-completed questionnaires have been utilized for the assessment of asthma control. However, due to the diversity in medical/social circumstances, they may not be optimal for use in all countries. The Japanese pediatric asthma guideline (JPGL) aims at higher levels of control compared with other international guidelines, based on a strong social demand for best care. We developed a new control test to help meet that demand. METHODS: A 34-item working questionnaire was developed based on input from pediatric asthma specialists and the caregivers of preschool children with asthma. The questionnaire was administered to caregivers of 565 patients aged <6 years who had physician-diagnosed asthma or ß2-agonist-responsive recurrent wheeze. Then, 6 questions for assessing JPGL-defined control levels were selected from the 34 questions by stepwise logistic regression methods using randomly selected questionnaires completed by two-thirds of the caregivers. We named that set of questions the Best Asthma Control Test for Preschoolers (Best ACT-P). Validation of Best ACT-P was performed using the remaining completed questionnaires. RESULTS: The 6 questions asked about the frequency/severity of cold-induced wheeze, nighttime awakening, exercise-induced symptoms, and disruption of family life due to asthma in the past 4 weeks and hospitalization in the past 12 months. The 6-item logistic model showed good statistical fit, and the scores for the physicians' ratings of the asthma control differed significantly in the hypothetical direction. CONCLUSIONS: Best ACT-P is a valid caregiver-completed questionnaire of asthma control in preschoolers in whom total control needs to be achieved.


Asunto(s)
Asma/diagnóstico , Encuestas y Cuestionarios , Asma/prevención & control , Cuidadores , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Japón , Masculino , Sensibilidad y Especificidad
18.
Water Sci Technol ; 72(4): 572-8, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26247755

RESUMEN

Effect of methanol and glycerol on nitrous oxide (N2O) emission in two laboratory-scale modified Ludzak Ettinger (MLE) processes was investigated during three distinct periods: dissolved oxygen (DO) control by intermittent aeration with a DO controller, and high and low aeration rates. N2O consumption rate in an anoxic tank and aeration mode influenced N2O emission rates from the MLE processes. In the DO control period, N2O emission rate from the glycerol-fed MLE process was higher than the methanol-fed counterpart, likely caused by a higher N2O consumption rate in an anoxic tank of the methanol-fed process. During the period of a higher aeration rate, N2O emission rates from both processes were comparable. In contrast, during the period of a lower aeration rate, N2O emission rate from the methanol-fed MLE process was higher than that from the glycerol-fed counterpart likely because of a higher degree of nitrite accumulation, corroborated by statistical analysis. N2O consumption activities of biomasses fed with the different carbon sources were distinct. However, the high activity did not necessarily result in a decrease in N2O emission rate from an aerobic tank and the effect of nitrite on the emission was stronger under the tested conditions.


Asunto(s)
Contaminantes Atmosféricos/metabolismo , Glicerol/metabolismo , Metanol/metabolismo , Óxido Nitroso/metabolismo , Reactores Biológicos , Oxígeno/química
19.
Artículo en Inglés | MEDLINE | ID: mdl-25560263

RESUMEN

In this study, the abundance and sequences of the amoA gene in ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) were defined in three wastewater treatment plants using activated sludge with biological nitrogen removal in different countries: Thailand, United States of America (USA), and Japan. Quantitative real-time polymerase chain reaction (PCR) and PCR coupled with denaturing gradient gel electrophoresis were used to find the comparative abundance and identity of AOB and AOA. The conditions at the Phuket WWTP in Thailand promoted the dominance of AOA amoA genes over AOB amoA genes, while conditions at the WWTPs in Japan and USA promoted growth of AOB. Three parameters that may have contributed to the AOA dominance in Phuket were longer SRT, higher temperature, and higher pH. The Phuket WWTP is a unique system that can be used to better understand the conditions that promote AOA growth and dominance over AOB. In addition, analysis of operational data in conjunction with AOA and AOB community structure from the Phuket WWTP may elucidate advantages of AOA in meeting stricter treatment standards.


Asunto(s)
Amoníaco/metabolismo , Archaea/aislamiento & purificación , Archaea/metabolismo , Bacterias/metabolismo , Aguas del Alcantarillado/microbiología , Eliminación de Residuos Líquidos/métodos , Archaea/clasificación , Bacterias/clasificación , Bacterias/aislamiento & purificación , Carga Bacteriana , Biota , Japón , Oxidación-Reducción , Tailandia , Estados Unidos
20.
Microbiol Resour Announc ; 13(3): e0127923, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38385666

RESUMEN

Here, we report a genome sequence of Afipia carboxidovorans strain SH125 isolated from an anammox reactor. This facultative anaerobic strain possesses the clade I-type nitrous oxide (N2O) reductase gene, devoid of nitrite- and nitric oxide reductase genes. Deciphering the genome will help explore N2O reducers instrumental in N2O mitigation.

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