Search

In this article, foam zero‐valent nickel (FZVN) was put forward as a promising zero‐valent metal for the pretreatment of azo dye wastewater (MO as a model contaminant). The characteristics of FZVN were evaluated by methods of Barrett‐Emmett‐Teller, scanning electron microscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. Moreover, influence of key experimental parameters, including oxygen concentration, presence of different acid, pH, and temperature on the MO decolorization were systematically ascertained. Furthermore, possible mechanism of MO removal by FZVN was investigated by using Liquid chromatography‐mass spectrometry (LC‐MS). Results showed that FZVN was a three‐dimensional pore material with a specific surface area of 3 m2 g−1. Moreover, anoxic condition, presence of acetic acid, higher temperatures and acid conditions were beneficial to decolorize MO by FZVN while the decolorization process obeyed the first order kinetic model with an apparent rate constant (kapp) of 0.162 min−1 at pH value of 4 (25°C). The activation energy Ea obtained from the decolorization reaction was 83.1 kJ mol−1. Based on LC‐MS results, the role of FZVN in the decolorization reaction process was suggested as follows: strong reductive, catalysis, and adsorption. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 686–694, 2018 [ABSTRACT FROM AUTHOR]

The lowest energy structures of Au and AuNi ( = 2-9) clusters have been researched using the CALYPSO structure searching method in conjunction with the density functional theory. It is found that the most stable structures of Au, Au8Ni and Au9Ni clusters reported by Tang et al. [C. M. Tang, X. X. Chen and X. D. Yang, Int. J. Mod. Phys. B 28, 1450138 (2014)] are low-lying isomers. The correct ground states and vibrational spectra are given in this paper. [ABSTRACT FROM AUTHOR]

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]

Abstract: The density functional method PW91P86 with relativistic effective core potentials (RECPs) and LANL2DZ basis set has been used to investigate the possible stable geometrical configurations and relative stabilities of the lowest-lying isomers of rhodium-doped gold clusters, Au n Rh (n=1–8). Several low-lying isomers were determined. The results indicate that the ground-state Au n Rh, n=1–8, clusters have planar structures except for n=5 and 8. The stability trend of the Au n Rh clusters shows that the clusters with even numbers of atoms are more stable than the clusters with odd numbers of atoms, indicating that the Au5Rh cluster is a magic cluster with high chemical stability. [Copyright &y& Elsevier]

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]

Abstract: Nickel-doped gold cluster anions, Au n Ni− (n =1–5), were investigated using the density functional method B3LYP with relativistic effective core potentials (RECP) and LANL2DZ basis set. The possible stable geometrical configurations with their electronic states are determined, and many of them in electronic configurations with a high spin multiplicity. The stability trend of the anionic clusters is compared to that of neutral clusters. Our results show that the one excess electron is strong enough to modify the known growth pattern and stability trend of the neutral Au n Ni clusters, and indicate that the stability and electron affinity of the clusters alter with odd-even oscillations as a function of the number of gold atoms. [Copyright &y& Elsevier]

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]

In order to strengthen the activity of biofilm on the carrier surface, the tourmpaline on polyurethane (TPU) carrier was prepared using waterborne polyurethane as medium. The physical properties of TPU carrier were characterized by scanning electron microscope(SEM) and water absorbency, and its effect on biofilm biomass and nitrifying ability was studied. The results showed that the tourmaline loading amount of TPU carrier can be affected by waterborne polyurethane. Tourmaline can optimize the number of polar groups of the TPU carrier and the pH of the nitrification condition. The amount of nitrobacteria and nitrate bacteria irreversibly adsorbed on the TPU carrier was increased by 74.82% and 71.89% , respectively. Correspondingly, the removing rate of NH+4 -N and NO-2 -N has risen by 8.12% and 9.08%, respectively, compared to the control without carrier. The TPU carrier was indicated to promote the nitrification.

The performance and feasibility of immobilization biological activated carbon (IBAC) were investigated to treat micro-pollutant water containing nitrobenzene. IBAC has been developed on the granular activated carbon by immobilization of selected and acclimated species of engineering bacteria to treat the micro-pollutant water containing nitrobenzene. The IBAC removal efficiencies for nitrobenzene, permanganate index, turbidity, UV, ammonia and nitrite were compared with granular activated carbon (GAC) process. Biological toxicity of influent and effluent of filter were determined. Amount of bacteria in carbon was measured when carbon filter was inoculated and circulated stably. The results showed that compared with GAC, it took short time for IABC to startup and recover to normal after impact burden. In addition, IBAC was more effective to treat micro-pollutants. In order to ensure security of drinking water, the influent nitrobenzene should be controlled below 26 microg/L. Effluent biological toxicity treated with IBAC was less than that with GAC. The performance of IBAC was much better than that of GAC. Amount of bacteria in both activated carbon filter increased first and then declined from inlet to outlet.