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1.
Water Sci Technol ; 88(10): 2661-2676, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38017684

RESUMO

Rural water environment governance in China still lacks a systematic and comprehensive assessment protocol to help analyze and improve such governance performance. The Analytic Hierarchy Process (AHP) method was employed in this study to build a governance assessment system that integrates ecological conditions, water pollution control, and public satisfaction. To cover these topics, the assessment system is composed of an indicator layer that is customized to rural water environment governance in China. The Beitang River, located in the rural region of Hangzhou, Zhejiang, China, was presented as a case study. Field investigation provided raw data for this assessment. A questionnaire survey was conducted to interview local residents on the governance performance. An additional survey with executives who played major roles in the governance was performed to reconstruct a water environment assessment on the Beitang River prior to the governance, in order to highlight the effects of the governance through contrast. The results showed consistency in the questionnaire survey and the assessment system. The AHP assessment system was able to reflect the improvement in the water quality, river ecology, and residential welfare after the governance, and suggested limits and future directions in the following upgrade programs for the river basin.


Assuntos
Processo de Hierarquia Analítica , Rios , Qualidade da Água , Conservação dos Recursos Naturais , China
2.
Opt Lett ; 48(13): 3375-3378, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37390134

RESUMO

We experimentally demonstrated polarization multiplexing schemes in a tilted fiber grating (TFBG) to achieve polarization-independent fiber-optic surface plasmon resonance (SPR) sensors. The first used two orthogonal polarized lights separated by a polarization beam splitter (PBS) that are p-polarized in polarization-maintaining fiber (PMF) and precisely aligned with the tilted grating plane, so as to achieve the transmission of p-polarized light in two opposite directions of the Au-coated TFBG to excite SPR. Alternatively, polarization multiplexing was also achieved by exploring two polarization components to achieve the SPR effect through a Faraday rotator mirror (FRM). The SPR reflection spectra are polarization-independent of the light source and any perturbations to fibers, which are explained by the superposition of p- and s-polarized transmission spectra in equal proportions. The spectrum optimization is presented to reduce the proportion of the s-polarization component. A polarization-independent TFBG-based SPR refractive index (RI) sensor with a wavelength sensitivity of 555.14 nm/RIU and an amplitude sensitivity of 1724.92 dB/RIU for small changes is obtained, exhibiting unique advantages of minimizing the polarization alterations by mechanical perturbations.


Assuntos
Tecnologia de Fibra Óptica , Ressonância de Plasmônio de Superfície
3.
Front Psychiatry ; 14: 1140908, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37275983

RESUMO

Aim: Appraise the clinical features and influencing factors of the hospitalization times and length of stay in bipolar disorder (BD) patients. Methods: This is a multicenter, observational, cohort study of patients diagnosed of type I or type II bipolar disorder. Five hundred twenty outpatients in seven hospitals from six cities in China were recruited from February 2013 to June 2014 and followed up using a continuous sampling pattern. The research included a retrospective period of 12 months and the prospective period of 9 months. The demographic and clinical features of the patients were collected. The influencing factors that could affect the length of stay (number of days spent in the hospital in the prospective period) were analyzed by poisson's regression and the hospitalization times (times of hospitalization in the prospective and retrospective period) was analyzed by general linear model. The selected variables included gender, age, years of education, occupational status, residence status, family history of mental disease, comorbid substance abuse, comorbid anxiety disorder, times of suicide (total suicide times that occurred in the retrospective and prospective period), polarity of the first mood episode, and BD type(I/II). Results: Poisson's regression analysis showed that suicide times [Incidence Rate Ratio (IRR) = 1.20, p < 0.001], use of antipsychotic (IRR = 0.62, p = 0.011), and use of antidepressant (IRR = 0.56, p < 0.001) were correlated to more hospitalization times. Linear regression analysis showed that BD type II (ß = 0.28, p = 0.005) and unemployment (ß = 0.16, p = 0.039) which might mean longer duration of depression and poor function were correlated to longer length of stay. However, patients who experienced more suicide times (ß = -0.21, p = 0.007) tended to have a shorter length of stay. Conclusion: Overall, better management of the depressive episode and functional rehabilitation may help to reduce the length of stay. BD patients with more hospitalization times were characterized by higher risk of suicide and complex polypharmacy. Patients at high risk of suicide tended to have inadequate therapy and poor compliance, which should be assessed and treated adequately during hospitalization. Clinical trial registration: www.ClinicalTrials.gov, Identifier: NCT01770704.

4.
Appl Opt ; 62(2): 291-297, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36630227

RESUMO

Microchannels fabricated by femtosecond laser-assisted chemical etching are of great use in biochemical analysis. In this paper, we study the morphology change of etched microchannels in fused silica by controlling the laser scan speed, and we find a significant difference between the chemical etched length and volume. The fabricated microchannels would gradually become tapered along the scan direction, which influences the flow of the hydrofluoric (HF) reagent and the etching rate. As a result, the difference ratios of the etched length and volume, respectively, reach -5.56% and -41.83% followed by the scan speed increasing from 5 to 200 µm/s. Microchannels with polarization independence and better aspect ratio could be obtained in a high-speed-scan mode. We suggest that laser-induced structural transformation from interconnected microcracks to nanogratings could be responsible for this change. Aforementioned results offer a feasible approach to achieve polarization-independent microchannels, which is in favor of accelerating the fabrication of three-dimensional microfluidic devices.

5.
Contrast Media Mol Imaging ; 2022: 8952791, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35685664

RESUMO

This research was aimed to explore the application of high-resolution computed tomography (HRCT) based on intelligent iterative reconstruction technique in the early diagnosis and treatment of bronchiolitis obliterans (BO) in children and to explore the efficacy of traditional Chinese medicine (TCM) in resolving phlegm and removing blood stasis. Sixty pediatric patients with BO were selected as the study subjects and diagnosed by HRCT scanning, and the scanned images were processed by iterative reconstruction technique. The patients were treated with TCM therapy of resolving phlegm and removing blood stasis alone (group A), HRCT-guided TCM therapy of resolving phlegm and removing blood stasis (group B), and iterative reconstruction HRCT-guided TCM therapy of resolving phlegm and removing blood stasis (group C). The results showed that the lung HRCT image after iterative reconstruction was closer to the original image than that after filtered back projection reconstruction, and the edge of the image after filtered back projection reconstruction was more blurred and the noise was higher. The image obtained by iterative reconstruction technique was smoother and clearer, and the image stability after iterative reconstruction was higher. The treatment results showed that the proportion of moderate and severe obstruction in group C was 5.18%, which was significantly lower than that in group A (18.75%) and group B (11.29%), and group B was significantly lower than that in group A (18.75%) (P < 0.05). The proportion of clinical effect in group C after treatment was 70.18%, significantly higher than that in group A (55.5%) and group B (63.34%), and that in group B was significantly higher than that in group A (55.5%) (P < 0.05). In summary, the lung HRCT after iterative reconstruction can more clearly and intuitively show the lesion site, which has a key role in guiding the early diagnosis and treatment planning of BO; the HRCT image based on iterative reconstruction technique combined with TCM treatment of removing blood stasis and resolving phlegm has a better therapeutic effect on children, with a high application value.


Assuntos
Bronquiolite Obliterante , Medicina Tradicional Chinesa , Algoritmos , Inteligência Artificial , Bronquiolite Obliterante/diagnóstico por imagem , Bronquiolite Obliterante/terapia , Criança , Humanos , Medicina Tradicional Chinesa/métodos , Tomografia Computadorizada por Raios X/métodos
7.
Front Psychiatry ; 12: 644038, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34248696

RESUMO

Background: Major depressive disorder (MDD) is often associated with suicidal attempt (SA). Therefore, predicting the risk factors of SA would improve clinical interventions, research, and treatment for MDD patients. This study aimed to create a nomogram model which predicted correlates of SA in patients with MDD within the Chinese population. Method: A cross-sectional survey among 474 patients was analyzed. All subjects met the diagnostic criteria of MDD according to the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10). Multi-factor logistic regression analysis was used to explore demographic information and clinical characteristics associated with SA. A nomogram was further used to predict the risk of SA. Bootstrap re-sampling was used to internally validate the final model. Integrated Discrimination Improvement (IDI) and Akaike Information Criteria (AIC) were used to evaluate the capability of discrimination and calibration, respectively. Decision Curve Analysis (DCA) and the Receiver Operating Characteristic (ROC) curve was also used to evaluate the accuracy of the prediction model. Result: Multivariable logistic regression analysis showed that being married (OR = 0.473, 95% CI: 0.240 and 0.930) and a higher level of education (OR = 0.603, 95% CI: 0.464 and 0.784) decreased the risk of the SA. The higher number of episodes of depression (OR = 1.854, 95% CI: 1.040 and 3.303) increased the risk of SA in the model. The C-index of the nomogram was 0.715, with the internal (bootstrap) validation sets was 0.703. The Hosmer-Lemeshow test yielded a P-value of 0.33, suggesting a good fit of the prediction nomogram in the validation set. Conclusion: Our findings indicate that the demographic information and clinical characteristics of SA can be used in a nomogram to predict the risk of SA in Chinese MDD patients.

8.
Sci Rep ; 10(1): 17975, 2020 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-33087812

RESUMO

The high coercivity of Nd-Fe-B magnets can also be obtained in the Ce-Fe-B magnets fabricated via the dual-main-phase (DMP) method in which the high abundance Ce was used to substitute Nd(Pr). The inhomogeneous distributions of the matrix grains in the DMP magnet play a key role in the enhanced magnetic performance. Compared with the single-phase magnet, more grain boundary phases encapsulating the matrix 2:14:1 grain are formed in the DMP magnet, which reduce the exchange coupling between adjacent magnetic grains. The switching field distribution and the interaction field distribution of the Ce-Fe-B magnets were determined by the first-order-reversal curves (FORC). The switching field peaks around 6 kOe, 11 kOe and 12 kOe in the FORC distribution indicate that three major reversal components coexist for the DMP magnet. The overlapp of the second and third switching field peaks reveals the presence of a pinning interaction within individual magnetic grains with a core-shell structure, which further improve the coercivity of the magnet.

9.
Plant Physiol ; 184(2): 973-987, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32732348

RESUMO

RNA SPLICING FACTOR1 (SF1) is responsible for recognizing the branch point site (BPS) sequence in introns and is critical for pre-mRNA splicing. In Arabidopsis (Arabidopsis thaliana), splicing factor1 (AtSF1) has been shown to retain the conserved function, but it is unexpected that null atsf1 mutants are viable. Here, we identified an allele of atsf1, named suppressor of thf1-4 (sot4), from suppressor screening for leaf variegation of thylakoid formation1 The sot4 mutant resulting from the G-to-R mutation at the highly conserved 198th amino acid residue within the functionally unknown domain exhibits leaf virescence associated with less accumulation of mature plastid ribosomal RNA, particularly under cold stress. Interestingly, the same point mutation in yeast Saccharomyces cerevisiae MUD synthetic-lethal 5p (SF1/Msl5p) also causes hypersensitivity to coldness and a low splicing activity for the introns with suboptimal BPS sequences. Transcriptomic profiling and reverse-transcription quantitative PCR analyses showed that expression of many genes were up- or downregulated in atsf1 via insufficient intron splicing. Our search for a BPS consensus from the retained introns in atsf1 transcriptomes, combined with RNA electrophoresis mobility shift assays, revealed that AtSF1 directly binds to the BPS consensus containing 5'-CU(U/A)AU-3'. Taken together, our data provide insight into a role for AtSF1 in regulating intron splicing efficiency, which helps plants acclimate to coldness.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/genética , Arabidopsis/fisiologia , Cloroplastos/genética , Cloroplastos/fisiologia , Resposta ao Choque Frio/genética , Resposta ao Choque Frio/fisiologia , Fatores de Processamento de RNA/fisiologia , Splicing de RNA/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas
11.
Int J Mol Sci ; 22(1)2020 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-33396301

RESUMO

Environmental stresses have driven plants to develop various mechanisms to acclimate in adverse conditions. Extensive studies have demonstrated that a significant reprogramming occurs in the plant transcriptome in response to biotic and abiotic stresses. The highly conserved and large multi-subunit transcriptional co-activator of eukaryotes, known as the Mediator, has been reported to play a substantial role in the regulation of important genes that help plants respond to environmental perturbances. CDK8 module is a relatively new component of the Mediator complex that has been shown to contribute to plants' defense, development, and stress responses. Previous studies reported that CDK8 module predominantly acts as a transcriptional repressor in eukaryotic cells by reversibly associating with core Mediator. However, growing evidence has demonstrated that depending on the type of biotic and abiotic stress, the CDK8 module may perform a contrasting regulatory role. This review will summarize the current knowledge of CDK8 module as well as other previously documented Mediator subunits in plant cell signaling under stress conditions.


Assuntos
Quinase 8 Dependente de Ciclina/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Fenômenos Fisiológicos Vegetais , Proteínas de Plantas/metabolismo , Plantas/metabolismo , Estresse Fisiológico , Quinase 8 Dependente de Ciclina/genética , Subunidades Proteicas
12.
Polymers (Basel) ; 9(6)2017 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-30970880

RESUMO

In this report, the ß-CD(AN-co-AA) hydrogel was used to remove the thorium(IV) [Th(IV)] from the water system, and the new adsorbent was characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The influences of contact time, pH value, ionic strength, solid-liquid ratio, initial Th(IV) concentration, and temperature on Th(IV) adsorption onto the functional hydrogel were researched. The results showed that the experimental data followed the Langmuir isotherm and the maximum adsorption capacity (qmax) for Th(IV) was 692 mg/g at pH 2.95, which approached the calculated (qe) 682 mg/g. The desorption capacity of Th(IV) in different HNO3 concentrations ranging from 0.005 to 0.5 M was also studied, and the percentage of the maximum desorption was 86.85% in the condition of 0.09 M HNO3. The selectivity of ß-CD(AN-co-AA) hydrogel was also be studied, the results indicated that this material retained the good adsorption capacity to Th(IV) even when the Ca2+, Mg2+, or Pb2+ existed in the system. The findings indicate that ß-CD(AN-co-AA) can be used as a new candidate for the enrichment and separation of Th(IV), or its analogue actinides, from large-volume solution in practical application.

13.
Forensic Sci Int ; 249: 271-9, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25747327

RESUMO

Gelatin, a representative simulant for soft tissue of the human body, was used to study the effects of 9 mm pistol bullet's penetration. The behavior of a bullet penetrating gelatin was quantified by the temporary cavity sizes in ballistic gelatin and the pressure values of bullet's impact. A numerical simulation model of a bullet penetrating the soft tissue simulant gelatin was built using the finite element method (FEM). The model was validated by the comparison between the numerical results and the experimental results. During a bullet penetrating ballistic gelatin, four stages were clearly observed in both the experiment and the numerical simulation: a smooth attenuation stage, a rolling stage, a full penetration stage, and a stage of expansion and contraction. The cavity evolution, equivalent stress field and the strain field in gelatin were analyzed by numerical simulation. Moreover, the effects of the bullet's impact velocities and angles of incidence on the temporary cavity in gelatin, its velocity attenuation, and its rolling angle were investigated, as well as the bullet's resistance and energy variation. The physical process and the interactive mechanism during a pistol bullet penetrating gelatin were comprehensively revealed. This may be significant for research in wound ballistics.


Assuntos
Balística Forense , Modelos Biológicos , Modelos Estatísticos , Ferimentos por Arma de Fogo , Transferência de Energia , Análise de Elementos Finitos , Gelatina , Humanos
14.
Bioresour Technol ; 177: 337-45, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25496956

RESUMO

A novel biological system coupling an UASB and a SBR was established to treat landfill leachate. In order to enhance organics and nitrogen removal, simultaneous denitritation and methanogenesis (SDM) was performed in the UASB. Free ammonia (FA) inhibition on nitrite-oxidizing bacteria (NOB) and process control was used to achieve nitrite pathway in the SBR. Results over 623 days showed that the maximum organic removal rate in the UASB and the maximum ammonium oxidization rate in the SBR was 12.7 kgCOD/m(3) d and 0.96 kgN/m(3) d, respectively. The system achieved COD, TN, and NH4(+)-N removal efficiencies of 93.5%, 99.5%, and 99.1%, respectively. By using FA inhibition coupled with process control, the nitrite pathway was started-up in the SBR at low temperatures (14.0-18.2°C) and was maintained for 142 days at temperatures below 15°C (the lowest level was 9.0°C). The predominant ammonia-oxidizing bacteria (AOB) explains essentially stable nitritation obtained.


Assuntos
Desnitrificação , Metano/biossíntese , Nitritos/química , Nitrogênio/isolamento & purificação , Compostos Orgânicos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Aerobiose , Amônia/análise , Compostos de Amônio/isolamento & purificação , Anaerobiose , Bactérias/metabolismo , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos/microbiologia , Temperatura Baixa , Concentração de Íons de Hidrogênio , Nitrificação , Oxigênio/análise , Purificação da Água/instrumentação
15.
Carbohydr Polym ; 94(1): 449-55, 2013 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-23544562

RESUMO

A novel sodium alginate-based superporous hydrogel (SPH) was prepared by the grafting copolymerization and micelle templating formed by the self-assembled anionic surfactant sodium n-dodecyl sulfonate (SDS). Fourier transform infrared (FTIR) spectra demonstrated that SDS was removed from the final hydrogel network. The formation mechanism of NaAlg-based SPH was proposed. Effect of SDS concentration on the morphologies and pore structure of the hydrogel was evaluated by Scanning Electron Microscopy (SEM), and the SDS-1.92 mM sample displays homogeneous and well-defined pores, which contribute to improve swelling ratio and swelling rate. The time-dependent swelling behaviors of the SDS-1.92 mM samples in various salt and pH solutions were investigated. The swelling in multivalent salt (Ca(2+), Al(3+))/pH 2 solutions displayed a well-known "overshooting effect", whereas, its swelling kinetics in Na(+)/pH 3-12 solutions followed Schott's pseudo second-order swelling kinetics model.

16.
Colloids Surf B Biointerfaces ; 88(1): 279-86, 2011 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-21798723

RESUMO

Novel fast-swelling porous guar gum-g-poly(sodium acrylate-co-styrene)/attapulgite (GG-g-P(NaA-co-St)/APT) superabsorbent hydrogels were prepared by simultaneous free-radical graft copolymerization reaction of guar gum (GG), partially neutralized AA (NaA), styrene (St) and attapulgite (APT) using N,N'-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution and the surfactant self-assembling templating pore-forming technique. Fourier transform infrared (FTIR) spectroscopy confirmed that the surfactant could be removed from the final hydrogel product by methanol/water (8:1, v/v) washing process and the surfactant only act as micelle template to form pores. The effect of surfactant type on the porous microstructure of the hydrogel was assessed by field emission scanning electron microscope (FESEM). It was shown that incorporation of proper amount of anionic surfactant sodium n-dodecyl sulfate (SDS) in the gelling process of the hydrogel can obviously enhance the swelling capacity and initial swelling rate. The salt-sensitivity of the SDS-added hydrogel in distilled water and 15 mmol/L NaCl, CaCl(2) solution or 15 mmol/L NaCl and CaCl(2) solution was investigated, and it was found that the swelling-deswelling capability is quite reversible. A similar reproducible on-off switching behavior was observed in the 1 mmol/L solution of phosphate buffer at pH 2.1 and 7.4.


Assuntos
Resinas Acrílicas/química , Galactanos/química , Hidrogéis/química , Compostos de Magnésio/química , Mananas/química , Gomas Vegetais/química , Compostos de Silício/química , Estireno/química , Tensoativos/química , Porosidade
17.
Nanotechnology ; 22(4): 045707, 2011 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-21169659

RESUMO

CoFe(2)O(4) nanoparticles were fabricated by a sol-gel method and then were coated with Co(3)Fe(7)-Co by means of a simple reduction process at different temperatures under 2% H(2) with the protection of argon to generate the dielectric-core/metallic-shell structure. The optimum reflection loss (RL) calculated from permittivity and permeability of the 80 wt% CoFe(2)O(4)/Co(3)Fe(7)-Co and 20 wt% epoxy resin composites reached - 34.4 dB, which was much lower than that of unreduced CoFe(2)O(4) and epoxy resin composites, at 2.4 GHz with a matching thickness of 4.0 mm. Moreover the RL exceeding - 10 dB in the maximum frequency range of 2.2-16 GHz was achieved for a thickness of composites of 1.0-4.5 mm with 600 °C thermal reduction process. The improved microwave absorption properties are a consequence of a proper electromagnetic match and the enhanced magnetic loss besides its dielectric loss due to the existence of the core/shell structure in CoFe(2)O(4) composites. Thus, the reductive CoFe(2)O(4) nanoparticles have great potential for being a highly efficient microwave absorber.

18.
J Environ Sci (China) ; 22(4): 481-5, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20617721

RESUMO

A two-stage upflow anaerobic sludge blanket (UASB) and sequencing batch reactor (SBR) system was introduced to treat landfill leachate for advanced removal of COD and nitrogen at low temperature. In order to improve the total nitrogen (TN) removal efficiency and to reduce the COD requirement for denitrification, the raw leachate with recycled SBR nitrification supernatant was pumped into the first-stage UASB (UASB1) to achieve simultaneous denitrification and methanogenesis. The results showed that UASB1 played an important role in COD removal and UASB2 and SBR further enhanced the nutrient removal efficiency. When the organic loading rates of UASB1, UASB2 and SBR were 11.95, 1.63 and 1.29 kg COD/(m3 x day), respectively, the total COD removal efficiency of the whole system reached 96.7%. The SBR acted as the real undertaker for NH4+-N removal due to aerobic nitrification. The system obtained about 99.7% of NH4+-N removal efficiency at relatively low temperature (14.9-10.9 degrees C). More than 98.3% TN was removed through complete denitrification in UASB1 and SBR. In addition, temperature had a significant effect on the rates of nitrification and denitrification rather than the removal of TN and NH4+-N once the complete nitrification and denitrification were achieved.


Assuntos
Reatores Biológicos , Poluentes Químicos da Água/química , Purificação da Água , Anaerobiose , Nitrogênio/química , Temperatura , Fatores de Tempo
19.
Huan Jing Ke Xue ; 30(6): 1681-8, 2009 Jun 15.
Artigo em Chinês | MEDLINE | ID: mdl-19662851

RESUMO

Under the well-controlled experimental conditions, the biological treatability of real municipal landfill leachate with high strength nitrogen and high chemical oxygen demand (COD) concentration using anoxic/anaerobic upflow anaerobic sludge bed (UASB) -sequencing batch reactor (SBR) combined process was conducted in laboratory. The results indicated: stable anoxic/anaerobic UASB-SBR process performance was developed during running continuously for five phase (116 d) when feed COD concentration was range from 1 237.2 mg/L to 12596.8 mg/L, effluent COD concentration was between 108.4 mg/L and 528.26 mg/L, and when the influent ammonia nitrogen (NH4(+) -N) was changed from 155.8 mg/L to 1298.0 mg/L, the effluent NH4(+) -N was varied from 0.12 mg/L to 4.1 mg/L, it achieved high COD and NH4(+) -N removal efficiency. In this present study, it is noted that the anoxic UASB1 has two significant effects: firstly, denitrification reaction of high efficiency was conducted for SBR nitrified effluent recirculated by using the abundant organic matters in the raw leachate as carbon source. Secondly, its removal COD was highly effected by anaerobic biodegradation. The effluent COD of anoxic UASB1 was biodegraded further in the anaerobic UASB2 and aerobic SBR, the maximum organic loading rates (OLR) (as COD) were 13.0, 2.09, 2.14 kg/(m3 x d), respectively. In addition, the correlation between OLR with OLRrem and COD removal efficiency of three reactors was studied, relation between nitrogen loading rate (NLR) with NH4(+) -N removal efficiency of SBR was tested by linear regression analysis, it was found that the OLR of anoxic UASB1, anaerobic UASB2 and aerobic SBR increased linearly with OLRrem. As to SBR, the correlation was significant between NLR (as N) with NLRrem. In addition, the OLR of three reactors shows second order exponential correlation with COD removal efficiency. At last, when the water temperature of SBR ranged from 20.7 degrees C to 10.3 degrees C, and dissolved oxygen was controlled below 1.0 mg/L, the efficiencies of nitrification and denitrification were above 98.5% and 97.7% during the whole experimental running period, it achieved advanced nitrogen removal.


Assuntos
Amônia/isolamento & purificação , Reatores Biológicos/microbiologia , Nitrogênio/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Aerobiose , Amônia/metabolismo , Anaerobiose , Nitrogênio/metabolismo , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/metabolismo
20.
Huan Jing Ke Xue ; 30(12): 3619-23, 2009 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-20187397

RESUMO

Nitrite accumulation during the denitration process with SBR treating pre-treated by anoxic/anaerobic up-flow anaerobic sludge bed (UASB) was observed at low temperatures. The effects of types of carbon sources on nitrite accumulation were investigated for comprehensive understanding the mechanism of nitrite accumulation. Experimental results clearly showed that nitrite accumulated obviously when five carbon sources (methanol, ethanol, sodium acetate, sodium propinoate and glucose), except for glucose, were used as electron donor. Additionally, nitrite accumulations were observed at four different initial nitrate concentrations and lower temperatures. The maximum concentrations of nitrite accumulation were 37.8, 21.5, 25.2 and 18.8 mg/L, respectively, and the corresponding nitrite accumulation rates (N/VSS x t) were 0.117, 0.136, 0.235 and 0.068 g/(g x d) during the nitrite accumulation period. Two break points of "nitrate knee" and "nitrite knee" on oxidation reduction potential (ORP) profile indicated that the reduction reactions of nitrate and nitrite were completed, respectively.


Assuntos
Reatores Biológicos , Nitritos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Reatores Biológicos/microbiologia , Carbono/química , Temperatura Baixa , Nitrogênio/metabolismo
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