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The influences of different fixed ways of polyurethane on the purification performance of wastewater treatment in biological contact oxidation were discussed, the polyurethane was put into biological contact oxidation by up-floating, sinking and general up-floating general sinking respectively, the relationship between microbial community structure and purification performance was analyzed. The results showed that polyurethane fixed by general up-floating general sinking could most efficiently remove pollutants, the purification rate of COD and NH4+ -N were 90% and 94% ; the attached microbial populations were with the largest number, the highest diversity, the strongest activity and the most reasonable function in this way. Therefore, the purification performance was affected by the fixed way of polyurethane in biological contact oxidation and the general up-floating general sinking was the most effective fixed way. [ABSTRACT FROM AUTHOR]

Microbial culture-independent technology, such as DNA fingerprinting technology, pyrosequencing, molecular hybridization technology, metagenomics, metatranscriptomics, metaproteomics, metabolomics and so on, has developed rapidly and been applied extensively in many fields, which could assist in the identification of microbial species from natural or anthropogenic environment rapidly and accurately. The microbial culture-independent technology has provided crucial in-sights for revealing microbial community structures, functions and remediation mechanism during bioremediation process and improving the detection efficiency of bioremediation. This review is mainly focused on the advanced applications of molecular biology and microbial culture-independent technology of "-- omics" in gauging microbial community structures, functions and dynamics at contaminated areas. [ABSTRACT FROM AUTHOR]

Extraction of metagenomic DNA from environmental sample was the main restrictive factor for the metagenomic sequencing. Three different extraction methods were used and compared in this study. The results indicated that the metagenomic DNA obtained from the activated sludge by Liquid Nitrogen Grinding + DNA Extraction Kit was the best sample due to the largest information and best quality, and D (260/280 nm) was between 1. 69 -1. 72. During the sample preparation for the next generation sequencing, D (260/280 nm) of the metagenomic DNA reached to 1. 83 after purification, which met the requirement of library construction. After the sequencing by Solexa Genome Analyzer System, the results showed that the forward sequencing of these two samples was successful, and the high quality data was about 90. 8%, which could be used for assemble. [ABSTRACT FROM AUTHOR]

To improve demulsifying property, the original biodemulsifier-producing bacterium, Bacillus mojavensis XH1, was mutated and bred by the combined treatment method using UV irradiation and niitrosoguanidine (NTG). A high efficient biodemulsifier-producing mutant XN5 with the better stability was obtained after continuous passages. The optimal cultural conditions were as follows: the mixture of 10 g/L glucose and 4 % liquid paraffin is the carbon source, the mixture of 4.0 g/L NH4Cl and 1.0 g/L yeast extract is nitrogen source, pH =6. 5 , the rotating rate is 140 r/min and the incubated time is 24 h. The 12 h and 24 h demulsification ratios of the mutant XN5 were 94. 17% and 98. 67% , which were 64. 81% and 15. 12% higher than that of the original strain XH1, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The density functional method PW91P86 with relativistic effective core potentials (RECP) and LANL2DZ basis set have been used to investigate the possible stable geometrical configurations and relative stabilities of the lowest-lying isomers of iridium-doped gold clusters, Au n Ir (n =1–8). Several low-lying isomers were determined. The results indicate that the ground-state Au n Ir, n =1–8, clusters have planar structures except for n =7. The stability trend of the Au n Ir clusters shows that even-numbered Au n Ir clusters are relatively more stable than the neighbouring odd-numbered ones, and indicating the Au2Ir clusters are magic cluster with high chemical stability. [ABSTRACT FROM AUTHOR]

In the process of destabilization and aggregation of aquatic colloidal particles, different mechanisms of agglomerants, coagulants and flocculants were analyzed. Classification and representatives of coagulants and flocculants in water treatment were introduced from such aspects as chemical composition, molecular weight, production source and nature of functional groups. Different technical characteristics between combination effect of flocculants and compound flocculants were put forward. The properties and development of microbial compound flocculants and the combination effect between bioflocclant and other flocculants were investigated. [ABSTRACT FROM AUTHOR]

To accurately regulate the production of active substances with demulsification characteristic by biological demulsification bacteria, the effects of different culture time, different components of culture solution and different types of carbon source and nitrogen source on a Bacillus mojavensis sp., which was isolated by our laboratory, were determined by demulsifying the O/W model emulsions, respectively. Results show that when the culture time is 14 -- 24 h, the highest demulsification activity of culture solution can be achieved. The culture and cell -- free culture have the high efficiency of demulsification while the bacterial cells do not. Hydrocarbons carbon source can induce this strain to produce the metabolites with demulsification activity and carbohydrate carbon source can promote the growth of cells. The mix carbon source containing fructose and liquid paraffin is most favorable for the growth and demulsification. Compared with the single nitrogen source, the mix nitrogen source containing ammonium nitrate and yeast extract is more beneficial to the growth and the demulsification production of this strain. The level of demulsifying activity of metabolites from this strain can be controlled by regulating the culture time, carbon source and nitrogen source. [ABSTRACT FROM AUTHOR]

The application of compound bioflocculant (CBF) in the treatment of low temperature and low turbidity water was studied in this work. The jar test was adopted to examine the effects of hydrogen ion concentration (pH), the CBF dosage and the cationic flocculant dosage on the removal efficiency of turbidity. Coagulation test shows that CBF has an effective performance with dosage of 5.0 - 17.5 mg/L in alkalescence environment. The optimal conditions for treatment of low temperature and low turbidity water by CBF are the dosage of 7.5 mg/L and pH of 8.0. The cationic flocculant can increase the production of flocs. Based on an overall analysis of removal efficiency and economic sectors, the optimal dosages for treatment of low turbidity water are CBF of 4 mg/L and PAFC of 10 mg/L, then the turbidity removal rate is 73. 0% and the CODMn, removal is 60.7%. [ABSTRACT FROM AUTHOR]

To improve the growth and efficiency of aerobic denitrifying bacteria, by adding different dose of magnetic powder (within 0.5 - 3.0 g/L, 0. 5 g/L for a gradient) and after 24 h, the growth absorbency, nitrate removal rate and dehydrogenase activity were determinated. Results show that the growth increases, and the nitrogen removal efficiency and dehydrogenase activity of T13 first increase and then decrease with increasing of magnetic powder dosage. The magnetic powder promotes the aerobic denitrifying bacteria growth and efficiency, and 2.0 g/L of magnetic powder is the optimal dosing quantity, under which the dehydrogenase activity and denitration nitrogen removal of T13 go to the maximum 73.9 µ/( mL⋅ h) and 100% respectively. [ABSTRACT FROM AUTHOR]