排序方式： 共有103条查询结果，搜索用时 390 毫秒
41.
The characterization of refractory organic substances (ROS) is very complicated because of their heterogeneous structure. Size-exclusion chromatography with continuous detection of dissolved nitrogen (LC-DN), dissolved organic carbon (LC-DOC), and UV-absorbance (LC-UV) is a very useful analytical tool for the characterization of changes of ROS in natural aquatic systems and in technological treatment. The effect of natural, oxidative, and biochemical processes on formation and removal of ROS is described. Additionally the role of hydrolysable carbohydrates in the composition of ROS is presented. 相似文献
42.
乍得Bongor强反转裂谷盆地高酸值原油成因 总被引：1，自引：1，他引：0
乍得Bongor盆地是受中非剪切带影响发育起来的中、新生代陆内强反转裂谷盆地,反转和走滑构造是盆地最显著的构造特征。所发现的原油主要为中质油(重度为20°～34°API),其次为重质油(重度小于20°API),普遍高含沥青质、高含蜡、高酸值、低含硫。为了探讨高酸值原油的成因,作者选择了该盆地15个不同酸值的原油样品,尝试应用高分辨率质谱分析原油有机酸的组成。分析结果表明,高酸值原油的有机酸主要由环烷酸组成;环烷酸碳原子数分布范围较宽,且以一环、二环、三环环烷酸为主。生物降解作用是形成高酸值原油的主要原因,而构造反转造成盆地抬升,则加速了生物降解作用的发生。 相似文献
43.
Laboratory experiments were initiated to study the biodegradability of oil after dispersants were applied. Two experiments were conducted, one at 20 degrees C and the other at 5 degrees C. In both experiments, only the dispersed oil fraction was investigated. Each experiment required treatment flasks containing 3.5% artificial seawater and crude oil previously dispersed by either Corexit 9500 or JD2000 at a dispersant-to-oil ratio of 1:25. Two different concentrations of dispersed oil were prepared, the dispersed oil then transferred to shake flasks, which were inoculated with a bacterial culture and shaken on a rotary shaker at 200 rpm for several weeks. Periodically, triplicate flasks were removed and sacrificed to determine the residual oil concentration remaining at that time. Oil compositional analysis was performed by gas chromatography/mass spectrometry (GC/MS) to quantify the biodegradability. Dispersed oil biodegraded rapidly at 20 degrees C and less rapidly at 5 degrees C, in line with the hypothesis that the ultimate fate of dispersed oil in the sea is rapid loss by biodegradation. 相似文献
44.
This study investigated the removal of two model pharmaceutically active compounds (PhAcs), viz., ibuprofen and triclosan, in lab‐scale engineered floodplain filtration (EFF) system. Biodegradation experiments were performed to acquire knowledge about the degradation of the targeted PhAcs, at an initial concentration of 350 µg/L. Biodegradation results showed that the two compounds were bio‐transformed to >70% after 15 days of incubation. Column tests were performed in a statistically significant manner to determine the adsorptive potential of the suggested filler layer in the EFF (C/C0), by varying the flow rate and initial concentration of the compound. It was observed based on the F and p‐values that the main effects (F = 3163, p < 0.005) were more significant than the interactive effects (F = 9561, p < 0.05) for both ibuprofen and triclosan removal. Besides, by performing the Student's “t” test, it was concluded that the flow rate plays a major role in determining the rapidness of achieving complete breakthrough than the initial concentration of both the compounds. The data obtained from column studies under biotic conditions indicated that the removal mechanism for PhAcs is mainly biotransformation based, and that an EFF system may be effectively used to remove these emerging compounds during ground water recharge for water recycling. 相似文献
45.
This study characterized sludge from an anoxic baffled reactor (ABR) used to treat textile dyeing wastewater. The process was run over 150 days. On day 152, five sludge samples were collected from compartments 1–5 of the ABR and a set of captive tests was conducted to investigate their particle size distributions (PSDs), dye biosorption and biodegradation properties, and dehydrogenase activity (DHA). The results indicated that the PSD of the five sludge samples from the ABR were similar. Methylene blue biosorption to the sludge samples followed the pseudo‐second‐order kinetic model and the actual biosorption process was controlled by external and intraparticle diffusion, simultaneously. After the sludge samples were cultivated for 24 h, the acid red GR dye removal efficiencies were 59.5, 68.3, 76.4, 61.5, and 65.4%, respectively. Eliminating dye biosorption, the dye biodegradation efficiencies were only 38.8, 46.3, 52.6, 48.3, and 46.0%, respectively. Furthermore, the DHA values were 28.2, 45.3, 56.5, 41.0, and 35.0 µg TF mL?1 h?1, respectively, and the DHA variation was in accordance with the dye biodegradation efficiency variation. 相似文献
46.
Most crude oils spread on open water to an average thickness as low as 0.1 mm. The application of dispersants enhances the transport of oil as small droplets into the water column, and when combined with the turbulence of 1 m waves will quickly entrain oil into the top 1 m of the water column, where it rapidly dilutes to concentrations less than 100 ppm. In less than 24 h, the dispersed oil is expected to mix into the top 10 m of the water column and be diluted to concentrations well below 10 ppm, with dilution continuing as time proceeds. Over the multiple weeks that biodegradation takes place, dispersed oil concentrations are expected to be below 1 ppm. Measurements from spills and wave basin studies support these calculations. Published laboratory studies focused on the quantification of contaminant biodegradation rates have used concentrations orders of magnitude greater than this, as it was necessary to ensure the concentrations of hydrocarbons and other chemicals were higher than the detection limits of chemical analysis. However, current analytical methods can quantify individual alkanes and PAHs (and their alkyl homologues) at ppb and ppm levels. To simulate marine biodegradation of dispersed oil at dilute concentrations commonly encountered in the field, laboratory studies should be conducted at similarly low hydrocarbon concentrations. 相似文献
47.
A finite element 2D Monte Carlo approach is used to evaluate the sensitivity of groundwater contaminant discharges to a Damkohler number ω and spatial variability in aquifer hydraulic conductivity, initial microbial biomass concentrations, and electron acceptor/donor concentrations. Bioattenuation is most sensitive to spatial variations in incipient biomass and critical electron donors/acceptors for ω ≥ 1 (i.e., when pore-water residence times are high compared to the time needed for microbial growth or contaminant attenuation). Under these conditions, critical reaction processes can become substrate-limited at multiple locations throughout the aquifer; which in turn increases expected contaminant discharges and their uncertainties at monitored transects. For ω ≤ 0.2, contaminant discharge is not sensitive to incipient biomass variations. Physical heterogeneities expedite plume arrival and delay departure at transects and in turn attenuate peak discharges but do not affect cumulative contaminant discharges. Physical heterogeneities do, however, induce transect mass discharge variances that are bimodal functions of time; the first peak beings consistently higher. A simple stream tube model is invoked to explain the occurrence of peaks in contaminant discharge variance. 相似文献
48.
塔里木盆地大宛齐油田的部分原油经受了不同程度的微生物降解作用,通过对该油田原油中轻烃分布特征的研究,
能更深入地认识微生物降解作用对轻烃的影响。结果表明,微生物优先消耗正构烷烃,其次为异构烷烃和环烷烃;从而导致
C6、C7轻烃三角图发生相应变化。在大宛齐原油中,随微生物降解程度的增加,正庚烷值和异庚烷值逐渐减小;当庚烷值
为0~21,异庚烷值为0~2.6时,为“微生物降解”原油。微生物降解作用亦能使苯/正己烷、甲苯/正庚烷两个比值增大,而
使正庚烷/甲基环己烷比值减小;基于甲苯/正庚烷、正庚烷/甲基环己烷两个比值建立的判别次生蚀变作用的模板,当原油
处于轻微微生物降解作用时,该模板易与蒸发分馏趋势混淆,需谨慎使用。 相似文献
49.
This study presents the degradation of phenanthrene using immobilized Mycoplana sp. MVMB2 isolated from contaminated soil. Papaya stem pretreated by two stage processes, treating with acid or alkali and drying, was used for the immobilization of Mycoplana sp. Alkali pretreated papaya stem was found to be most effective in cell uptake compared to acid treated one. The maximum immobilization capacity at various physiochemical conditions for the alkali pretreated papaya stem was found to be at 320 min time, pH 6.5, 30°C temperature, and 18.6 × 106 cells/mL initial concentrations. The adsorption mechanism of Mycoplana sp. MVMB2 on pretreated papaya stem was assessed using various kinetic and isotherm models. The immobilization of Mycoplana sp. MVMB2 on to pretreated papaya stem was corroborated by scanning electron microscopy and Fourier transformed IR spectroscopy analysis. The performance of immobilized cells in batch reactor showed more than 95% phenanthrene degradation within 72 h, whereas, free cells were found to require 120 h. The immobilized cells also showed better degradation performance in the packed column study. 相似文献
50.
1, 3, 5-TMB (trimethylbenzene) has been considered as priority pollutant by several environmental agencies due to its high toxicity, carcinogenicity and mutagenic activity. Two bacteria with ability of degrading 1, 3, 5- TMB were isolated from crude oil contaminated soil. The optimal pH value and temperature for the growth of these bacteria were 7.0 and 30℃. 1, 3, 5- TMB was used as sole carbon and energy source by both strains. Strain A was identified as Staphylococcus sciuri and Strain C was Microbacterium schleiferi, both of which were facultative anaerobic bacteria. 1, 3, 5-TMB was degraded by strain C with efficiency of 41.2±1.8%. The bacteria offered new source for biodegradation of BTEX and bioremediation of oil-contaminated soil and groundwater. 相似文献