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Search Results: 1 - 10 of 6451 matches for " AOB population "
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Variation of functional bacteria during start-up and operation of partial nitrification process

CHEN Xiao-Xuan,LIU Chun,YANG Jing-Liang,ZHANG Run,YANG Hui-Na,

微生物学通报 , 2012,
Abstract: Objective] Partial nitrification-anammox is considered as the shortest?process for biological nitrogen removal and partial nitrification is the important part of this process. Methods] The variation of functional bacteria during start-up and stable operation of partial nitrification process was investigated in a SBR bioreactor in this study. Results] The results indicated that ammonia-oxidizing bacteria (AOB) population was expanded significantly and nitrite-oxidizing bacteria (NOB) population was inhibited when DO concentration was controlled lower than 1 mg/L and ammonia loading of the influent increased gradually. As a result, start-up and stable operation of partial nitrification process was realized. When ammonia volumetric loading of the influent was 0.055 kg/(m3·d), the average ammonia removal volumetric loading and sludge loading were 0.043 kg/(m3·d) and 0.16?kg/(kg·d), respectively. In addition, the average nitrite accumulation rate was 83.4% at this time. AOB population density and relative abundance increased from 4.5×104 CFU/mL to 1.5×107CFU/mL and from 0.18% to 7.25%, respectively, during start-up and stable operation of partial nitrification process. At the same time, NOB population density and relative abundance decreased from 2.0×105 CFU/mL to 1.5×104 CFU/mL?and from 5.51% to 2.14%, respectively. Conclusion] The expansion of AOB population was responsible for realization of partial nitrification and ammonia removal. High ammonia concentration and loading?also caused the activity inhibition of partial nitrification.
Ammonium Oxidizing Bacteria Activity and Nitrification Rate in Oil Contaminated Wetland Soil under Remediation with Nutrient Supplements and Leguminous Plants  [PDF]
Richard C. John, Emem S. Ntino, Joseph P. Essien
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.74049

Previous investigation on the impact of crude oil on the growth of tropical legumes and its effect on nitrogen dynamics in wetland ultisol showed that oil contamination reduced N uptake by plants but increased N accumulation in soil microbial biomass. Moreover, the presence of hydrocarbons widened the C/N ratio in soil and led to more available N being immobilized by soil microorganisms. The present study was carried out to evaluate the activity of ammonium oxidizing bacteria (AOB) and their nitrification potential rate (NPR) in wetland soil under a remediation course. Mineralization studies showed that ammonium-N levels decreased while nitrate-N increased progressively in the uncontaminated soil (control) cultivated with leguminous plants (cover crops) during the 12 weeks remediation period. However, the remediated soils were affected in different ways. The experimented soil cultivated with Centrosema pubescens had higher mineral nitrogen (NH4-N, NO3-N, NO2-N, Total N and P) than soil cultivated with Calopogonium mucunoides and Pueraria phaseoloides. AOB counts recorded were in the ranged, 2.25 × 102 - 2.66 × 105, 2.31 × 102 - 2.11 × 104 and 4.25 × 102 - 2.98 × 104 respectively. The highest NPR was found in uncontaminated soil (11.68 - 60.92 nmol N/g dry weight soil (DWS)) followed by soil treated with poultry manure (9.65 - 24.86 nmol N/g DWS/h), NPK (7.88 - 39.45 nmol N/g DWS/h) and in the oil-contaminated soil (0.11 - 1.87 nmol N/g DWS/h). The relations between NH4-N concentration and NPR in soil cultivated with Centrosema (r = 0.852), Calopogonium (r = 0.745) and Pueraria (r = 0.722) were positively significant at 95% confidence limit. Similarly the relations between AOB density and NPR for Centrosema (r = 0.654; P = 0.05), Calopogonium (r = 0.588; P = 0.05) and Pueraria (r = 0.518; P = 0.05) were significant. The findings imply that nitrification potential of crude oil- contaminated soil differs significantly with the nutrient amendment/treatment technique adopted for remediation. Our research has shown that treatment of uncontaminated soil with cover crops increased AOB and nitrification rate. More so, contaminated soil

Effects of Wheat-Faba Bean Intercropping on Soil Microbial Community Structure in the Rhizosphere  [PDF]
Yongbo Xu, Baokun Lei, Yanfeng Tang
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.911096
Abstract: Phospholipid fatty acids (PLFA) analysis and real-time quantitative PCR were used to investigate the effect of wheat-faba bean intercropping on soil microbial community in the rhizosphere and ammonia monooxygenase (amoA) gene abundances of ammonia-oxidizing archaea (AOA) and bacteria (AOB) at harvest stage via field trials in the red soil. We found that the bacteria and fungi of faba bean and actinomycetes of wheat in the rhizosphere showed significant (p < 0.05) difference between intercrops and monocrops at harvest. In total, 37 PLFA were detected at harvest stage in the rhizosphere, including 31 bacterial PLFA, 3 fungal PLFA, and 3 actinomycete PLFA. Compared with the rhizosphere of monocropped faba bean, a lower AOB abundance was found in the intercropping at harvest stage, whereas no significant difference in the AOB abundance was found in the rhizosphere of monocropped and intercropped wheat. There was no significant difference in the AOA abundance between monocrops and intercrops rhizosphere, but a higher AOA abundance in the intercropping systems was found. After intercropping, the abundance of AOB in rhizosphere was significantly higher than that of AOA. Our findings suggest that wheat-faba bean intercropping may change the micro-environment and microbial community structure in the rhizosphere.
Long-Term Management of Hepatitis C-Seropositive Subjects with AntiOxidant Biofactor (AOB ), a Fermented Food Supplement
Acta Medica Okayama , 2010,
Abstract: The efficacy of AntiOxidant Biofactor (AOB(R)) for the management of apparently healthy subjects with chronic hepatitis C infection was investigated. A total of 60 subjects (35 males, 25 females) participated in the trial. AOB was given orally in 2 packs (3g per pack) 3 times per day. 17 subjects had taken AOB for 3 years, 31 subjects up to 2 years, and 41 subjects up to one year. The initial mean (SD) serum alamine aminotransferase (ALT) level was 46.3+/-35.4IU/L, and significant (p0.05, paired t-test) reductions in the mean serum ALT levels were observed at 6 months (38.6+/-21.5IU/L), 18 months (31.9+/-18.1IU/L), 2 years (31.2+/-14.6IU/L), and 3 years (28.0+/-15.9IU/L). Those presenting with high serum ALT levels (30 subjects) demonstrated significant levels (p0.05, paired t-test) of reduction in the mean serum ALT levels at 6, 12, 18, 24, and 36 months of treatment. No side effects were observed and the AOB treatment was well tolerated by all subjects.
Ni Made Susun Parwanayoni
Bumi Lestari , 2012,
Abstract: This research was carried out at Nusa Dua Lagoon, Nusa Dua – Bali in the year of 2006. The research was aimed to find out the concentration of heterotrophic bacteria, algae and protozoa, as well as to observe the change of the population in the lagoon. Results of this study showed that the highest concentration of the population of heterotrophic bacteria was on pond 4b (aerated pond 2), algae population was highest at pond 5a (sedimentation pond 1), and the population of protozoa was highest on pond 5b (sedimentation pond 2). The population of heterotrophic bacteria was replaced by algae and then algae was taken over by protozoa.
Impact of acetochlor on ammonia-oxidizing bacteria in microcosm soils

LI Xinyu,ZHANG Huiwen,WU Minna,SU Zhencheng,ZHANG Chenggang,

环境科学学报(英文版) , 2008,
Abstract: Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and community composition of AOB in soil amended with three concentrations of acetochlor (50, 150, 250 mg/kg) and the control (0 mg acetochlor/kg soil) in a microcosm experiment by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and the phylogenetic analysis of excised ...
环境工程学报 , 2014,
Abstract: 针对实际海水养殖废水低碳高氮的特点,采用间歇式活性污泥法(SBR)和好氧活性污泥添加硅藻土载体的方式,考察硅藻土载体和活性污泥共同作用下的好氧曝气系统对海水养殖废水中氨态氮(NH4+-N)、亚硝酸态氮(NO2--N)和化学耗氧量(COD)的去除效果,以及对污泥沉降性能和硝化细菌特征的影响。实验结果表明,常温条件下,溶解氧(DO)≥4.5mg/L,pH控制在7.0~8.0,HRT为11h,沉降时间10min,反应器可以处理NH4+-N浓度在50mg/L左右的海水养殖废水,NH4+-N和COD去除率分别达到98.93%左右和76.62%以上,NO2--N出水浓度低于0.028mg/L。载体污泥颗粒照片和扫描电镜结果表明,添加硅藻土载体内核后,颗粒污泥的成熟期缩短,颗粒的稳固度和沉降性能提高。在系统启动成功稳定运行后,通过FISH分析表明,在氨氧化菌(AOB)与亚硝酸盐氧化菌(NOB)成为优势菌群后,AOB大约占总菌群的33.5%,并且AOB与NOB菌群数量约为1:1.33,AOB和NOB两大类菌群之和约占总菌群的77.2%,成为系统中优势菌群。
- , 2018, DOI: 10.11918/j.issn.0367-6234.201706009
Abstract: 为考察纳米铜对自养脱氮亚硝化工艺的影响,在SBR反应器内分别进行短期影响实验(8 h)及长期影响实验(20 d),研究氨氮氧化速率、氮素转化规律及污泥性能的变化规律.短期实验结果表明,低质量浓度的纳米铜(≤1 mg/L)对亚硝化有促进作用,纳米铜质量浓度在3~30 mg/L内严重抑制自养脱氮亚硝化,氨氮氧化速率降低率为21.9%~44.9%.纳米铜为50 mg/L时,由于质量浓度过高导致纳米颗粒团簇,降低了真正作用于细胞的量,亚硝化活性得到强化.长期实验结果表明,长期暴露在低质量浓度(1 mg/L)的纳米铜环境中,氨氮氧化速率受到严重抑制,氨氮去除率从90%降低为44.8%,氨氧化细菌比亚硝酸盐氧化细菌对纳米铜更加敏感.在长期作用后,污泥中的铜含量增加,胞外聚合物含量增加,解除纳米铜抑制后,两者均降低.纳米铜对自养脱氮亚硝化工艺的微生物活性、脱氮能力、污泥性能均具有较大的影响.
The short-term and long-term effects of Cu nanoparticles (NPs) on partial nitrification (PN) process were studied in SBR. The ammonia oxidation rate, nitrogen removal and sludge property were analyzed within exposure of different concentrations of Cu NPs. The short-term result suggested that the Cu NPs with 1 mg/L was beneficial for PN process, while the NPs in 3-30 mg/L significantly inhibit PN. As a result, the ammonia oxidation rate decreased to 21.9%-44.9% of the initial value. When the Cu NPs was 50 mg/L, the PN process was enhanced, which was mainly because the aggregation reduced the actual concentration of NPs acting on the microorganisms. Long-term exposure within low Cu NPs (1 mg/L) could also suppress the PN process, and the ammonia removal efficiency decreased to 44.8% from 91%. The ammonia-oxidizing bacteria was more severe to the Cu NPs than nitrite-oxidizing bacteria. After the long-term exposure, the copper and extracellular polymeric substance in sludge both increased, and then decreased when no Cu NPs was added to the PN system anymore. Cu NPs performed a significant effect on microbial activity, nitrogen removal ability and sludge property.
The Correctional Model of Population Development Equation  [PDF]
Man Liu, Daqing Liao, Qianqian Zhu, Zhengming Wang
Modeling and Numerical Simulation of Material Science (MNSMS) , 2013, DOI: 10.4236/mnsms.2013.34019

The problem of population development has always been the key problem of restricting the development of our country. In order to increase the prediction accuracy, we analyze the exponential model, logistic model and continuous model. Also, the improved discrete population development model is provided to control the quantity and improve the quality of population.

Maximizing Sampling Efficiency  [PDF]
Harmon S. Jordan
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.411209
Abstract: Background and Goals: Although health care quality improvement has traditionally involved extensive work with paper records, the adoption of health information technology has increased the use of electronic record and administrative systems. Despite these advances, quality improvement practitioners now and for the foreseeable future need guidance in defining populations of individuals for study and in selecting and analyzing sample data from such populations. Statistical data analysis in health care research often involves using samples to make inferences about populations. The investigator needs to consider the goals of the study, whether sampling is to be used, and the type of population being studied. While there are numerous sampling strategies designed to conserve resources and yield accurate results, one of these techniques—use of the finite population correction (FPC)—has received relatively little attention in health care sampling contexts. It is important for health care quality practitioners to be aware of sampling options that may increase accuracy and conserve resources. This article describes common sampling situations in which the issue of the finite population correction decision often arises. Methods: This article describes 3 relevant sampling situations that influence the design and analysis phases of a study and offers guidance for choosing the most effective and efficient design. Situation 1: The study or activity involves taking a sample from a large finite target population for which enumerative inferences are needed. Situation 2: The population is finite and the study is enumerative. A complete enumerative count of “defects” in the process is needed so that remediation can occur. Here, statistical inference is unnecessary. Situation 3: The target population is viewed as infinite; such populations are “conceptual populations” [1] or “processes”. Results: The article shows how savings in resources can be achieved by choosing the correct analytic framework at the conceptualization phase of study design. Choosing the right sampling approach can produce accurate results at lower costs. Several examples are presented and the implications for health services research are discussed. Conclusion: By clearly specifying the objectives of a
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