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排序方式: 共有546条查询结果,搜索用时 31 毫秒
501.
502.
Jia Liu Kaiming Peng Xiangfeng Huang Lijun Lu Hang Cheng Dianhai Yang Qi Zhou Huiping Deng 《环境科学学报(英文版)》2011,23(6):1020-1026
Exploration of biodemulsifiers has become a new research aspect. Using waste frying oils (WFOs) as carbon source to synthesize
biodemulsifiers has a potential prospect to decrease production cost and to improve the application of biodemulsifiers in the oilfield.
In this study, a demulsifying strain, Alcaligenes sp. S-XJ-1, was investigated to synthesize a biodemulsifier using waste frying oils as
carbon source. It was found that the increase of initial pH of culture medium could increase the biodemulsifier yield but decrease the
demulsification ratio compared to that using paraffin as carbon source. In addition, a biodemulsifier produced by waste frying oils and
paraffin as mixed carbon source had a lower demulsification capability compared with that produced by paraffin or waste frying oil as
sole carbon source. Fed-batch fermentation of biodemulsifier using waste frying oils as supplementary carbon source was found to be a
suitable method. Mechanism of waste frying oils utilization was studied by using tripalmitin, olein and tristearin as sole carbon sources
to synthesize biodemulsifier. The results showed saturated long-chain fatty acid was difficult for S-XJ-1 to utilize but could effectively
enhance the demulsification ability of the produced biodemulsifier. Moreover, FT-IR result showed that the demulsification capability
of biodemulsifiers was associated with the content of C=O group and nitrogen element. 相似文献
503.
Hai Yan Xiaojing Yang Jian Chen Chunhua Yin Chengbin Xiao Hao Chen 《环境科学学报(英文版)》2011,23(7):1165-1170
Synergistic removal of aniline by carbon nanotubes and the enzymes of Delftia sp. XYJ6, a newly isolated bacterial strain for
biodegrading aniline, was investigated. It showed that biodegradation rate of aniline was increased with the augment of protein
concentration in cell-free extract of Delftia sp. XYJ6. The adsorption amount of aniline by multi-walled carbon nanotubes (MWCNTs)
was slightly higher than that by single-walled carbon nanotubes (SWCNTs), however the adsorption amount of protein of Delftia sp.
XYJ6 by MWCNTs was lower than that by SWCNTs. Much more amount of aniline could be removed by CE of Delftia sp. XYJ6 in
the presence of SWCNTs than MWCNTs, which indicated that an efficient reaction between aniline and enzymes of Delftia sp. XYJ6
on the surface of SWCNTs played a key role in the rapid enzymatic biodegradation of aniline. This study is not previously reported and
may be useful in basic research and the removal of aniline from wastewater. 相似文献
504.
A halotolerant bacterial strain VA1 isolated from marine environment was studied for its ability to utilize polycylic aromatic
hydrocarbons (PAHs) under saline condition. Anthracene and pyrene were used as representatives for the utilization of PAH by the
bacterial strain. Glucose and sodium citrate were used as additional carbon sources to enhance the PAH utilization. The strain VA1
was able to utilize anthracene (73%) and pyrene (66%) without any additional substrate. In the presence of additional carbon sources
(glucose/sodium citrate) the utilization of PAH was faster. PAH was utilized faster by VA1 in the presence of glucose than sodium citrate.
The stain utilized 87% and 83% of anthracene and pyrene with glucose as carbon source and with sodium citrate the strain utilized 81%
and 76% respectively in 4 days. Urea as an alternative source of nitrogen also enhanced the utilization of PAHs (anthracene and pyrene)
by the bacterial strain up to 88% and 84% in 4 days. Sodium nitrate as nitrogen source was not able to enhance the PAH utilization rate.
Phenotypic and phlyogenetic analysis proved that the PAHs utilizing halotolerant strain VA1 belongs to Ochrobactrum sp. 相似文献
505.
506.
大亚湾裸甲藻种群动态及其关键调控因子 总被引:2,自引:0,他引:2
2008年1—12月对大亚湾养殖海域裸甲藻种群动态和主要环境因子进行了周年调查。结果表明,大亚湾海域裸甲藻类群以直径约为16~22μm的小型裸甲藻(Gymnodinium sp.)为主,另外米氏凯伦藻(Karenia mikimotoi)、链状裸甲藻(Gymnodnium catenatum)和血红哈卡藻(Akashiwo sanguinea)也有少量出现。裸甲藻种群密度呈现出明显的季节性变化特征:5月出现裸甲藻密度高峰,全年最大密度达到903 cells.mL-1,秋冬季节密度最小。不同站位裸甲藻密度也具有明显的空间分布差异,养殖及近岸海域密度普遍高于外海对照区。相关性分析结果表明,裸甲藻密度的关键调控因子包括温度、化学需氧量(COD)、可溶性有机氮(DON)和尿素浓度。裸甲藻高密度、高频率出现的温度范围在24~26℃,DON和尿素的质量浓度范围分别为N 156.38~187μg·L-1和N 17.4~38.9μg·L-1。在温度适宜的条件下,尿素等有机氮含量的增加可能成为裸甲藻赤潮的触发因子。 相似文献
507.
温度、曝气和沉积物对绿潮硬毛藻分解的影响 总被引:2,自引:0,他引:2
为了解绿潮优势种——硬毛藻在温度、曝气和沉积物作用下的分解过程及三因素的效应大小,通过室内模拟研究了不同环境条件下硬毛藻早期分解过程中生物量、分解速率及藻体磷释放率的变化,分析了不同环境因子对藻体分解影响的效应大小.结果表明,高温(20~30℃)和添加沉积物均能促进硬毛藻的腐烂分解及藻体磷素释放,其中,30℃条件下含沉积物处理的最大分解速率可达12.13%·d-1,14 d后藻体磷释放率为90%以上.曝气一方面可通过扰动加速藻体生物量的损失和分解速率,另一方面提供了好氧环境,抑制了藻体生物分解和磷素释放,因而其影响效应较低.研究表明,高温和添加沉积物均可加速丝状硬毛藻的分解和藻体磷素释放,夏季应及时清除水体中滋生和衰亡的藻体. 相似文献
508.
Jiewei Liu Junwei M Yanzhong Liu Ya Yang Dongbei Yue Hongtao Wang 《环境科学学报(英文版)》2014,26(10):2076-2083
The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids(m/m). A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration(SRF)decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity. 相似文献
509.
A bacterium strain Y3,capable of efficiently degrading pendimethalin,was isolated from activated sludge and identified as Bacillus subtilis according to its phenotypic features and 16 S rRNA phylogenetic analysis.This strain could grow on pendimethalin as a sole carbon source and degrade 99.5%of 100 mg/L pendimethalin within 2.5 days in batch liquid culture,demonstrating a greater efficiency than any other reported strains.Three metabolic products,6-aminopendimethalin,5-amino-2-methyl-3-nitroso-4-(pentan-3-ylamino) benzoic acid,and 8-amino-2-ethyl-5-(hydroxymethyl)-1,2-dihydroquinoxaline-6-carboxylic acid,were identified by HPLC-MS/MS,and a new microbial degradation pathway was proposed.A nitroreductase catalyzing nitroreduction of pendimethalin to 6-aminopendimethalin was detected in the cell lysate of strain Y3.The cofactor was nicotinamide adenine dinucleotide phosphate(NADPH) or more preferably nicotinamide adenine dinucleotide(NADH).The optimal temperature and pH for the nitroreductase were 30℃ and 7.5,respectively.Hg~(2+),Ni~(2+),Pb~(2+),Co~(2+),Mn~(2+) Cu~(2+),Ag~+,and EDTA severely inhibited the nitroreductase activity,whereas Fe~(2+),Mg~(2+),and Ca~(2+) enhanced it.This study provides an efficient pendimethalin-degrading microorganism and broadens the knowledge of the microbial degradation pathway of pendimethalin. 相似文献