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Screening of flocculant-producing strains by NTG mutagenesis

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Journal of Environmental Sciences 2005年第3期17卷 494-498页

作者： HUANGXiao-wu CHENGWen HUYong-you SchoolofEnvironmentalScienceandEngineering SouthChinaUniversityofTechmologyGuangzhou510640China SchoolofEnvironmentalScienceandEngineering SouthChinaUniversityofTechmologyGuangzhou510640China

Screening of new microorganism being able to produce efficiently flocculants was carried out. A new model for screening efficient flocculant-producing strains was designed and tested. The results showed that this model for screening efficient flocculant-producing strains is very reliable and can greatly shorten the screening period. 13 flocculant-producing strains were isolated from activated sludge by conventional method. A strain, designated as HHE6, produced the bioflocculant with the turbidity removal 98% for kaolin suspension. Six of 13 strains selected as the original strains were treated with NTG as mutagen, and five mutant strains(HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) with high flocculation efficiency was obtained by selection, which exhibited the flocculation rate for kaolin suspension above 90%. Strains HHE6, HHE-P7, and HHE-P24 were classified as Penicillium purpurogenum, HHE-P21 as Penicillium cyclopium, HHE-A26 as Aspergillus versicolor and HHE-A8 as Aspergillus fumigatus, and it is hitherto unreported for biofloccutant-producing strains of Penicillium. The growth of the six strains(HHE6, HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) had similar curves, i.e. firstly increasing rapidly, keeping relatively constant then and finally decreasing gradually with cultivation time. The production of bioflocculants by strains showed the similar pattern to strain growth.

关键词： bioflocculant mutation breeding bioflocculant-producing strains Penicillium Aspergillus

Anaerobic digestion of kitchen wastes in a single-phased anaerobic sequencing batch reactor(ASBR) with gas-phased absorb of CO_2

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Journal of Environmental Sciences 2005年第2期17卷 249-255页

作者： ZHANGBo HEZheng-guang ZHANGLi-li XUJian-bo SHIHong-zhuan CAIWei-min SchoolofEnvironmentalScienceandEngineering ShanghaiJiaotongUniversityShanghai200240China SchoolofEnvironmentalScienceandEngineering ShanghaiJiaotongUniversityShanghai200240China／／HarbinInstituteofTechnologyHarbin150001China

The performance of the single-stage anaerobic digestion of kitchen wastes was investigated in an anaerobic sequencing batch reactor(ASBR) with gas-phased absorb of CO 2. The ASBR was operated at four chemical oxygen demand(COD) loading rates, 2.8, 5.1, 6.2 and 8.4 g/(L·d) respectively. The COD loading rate was increased with the TS concentration and HRT changing. At maximum COD loading rate of 8.4 g/(L·d), the COD, total solid(TS) removal rate and methane gas yield were 69%, 68% and 2.5 L/(L·d) respectively. The operation of the reactor with gas-phased absorb of CO 2 was stable in spite of the low pH(2.6—3.9) and high concentration of TS(142 g/L) of input mixture. The output volatile fatty acid(VFA) concentration was between 2.7—4.7 g/L and had no inhibition on the methanogenic microorganism. The reactor without gas-phased absorb of CO 2 became acidified when the total COD loading rate was increased to 5.1 g/(L·d). Stoichiometry of the methanogenesis for kitchen wastes showed a considerable amount of alkaline will be required to keep pH in the appropriate range for the methanogenic microorganism based on theoretical calculation. Gas-phased absorb of CO 2 effectively reduced the alkaline consumption, hence avoided excessive cation into the reactor.

关键词： kitchen wastes methanogenesis gas-phased CO 2

Visible light induced photodegradation of organic pollutants on nitrogen and fluorine co-doped TiO_2 photocatalyst

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Journal of Environmental Sciences 2005年第1期17卷 76-80页

作者： WANGZheng-peng XUJun CAIWei-min ZHOUBao-xue HEZheng-guang CAIChun-guang HONGXiao-ting SchoolofEnvironmentalScienceandEngineering ShanghaiJiaotongUniversityShanghai200240China

The nitrogen and fluorine co doped TiO 2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetra butyl titanate with ammonium fluoride. Nitrogen and fluorine co doping causes the absorption edge of TiO 2 to shift to a lower energy region. The photocatalytic activity of co doped TiO 2 with anatase phases was found to be 2 4 times higher than that of the commercial TiO 2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co doped TiO 2 powders only contain anatase phases even at 1000℃. Apparently, ammonium fluoride added retarded phase transformation of the TiO 2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co doped TiO 2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO 2 to shift to a lower energy region.

关键词： photocatalyst visible light nitrogen and fluorine co-doped phenol band gap

Absorption of phosphorus from wastewater by aged refuse excavated from municipal solid waste landfill

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Journal of Environmental Sciences 2005年第1期17卷 25-29页

作者： ZHAOYou-cai SHAOFang TheStateKeyLaboratoryofPollutionControlandResourceReuse SchoolofEnvironmentalScienceandEngineeringTongjiUniversityShanghai200092China

Municipal solid waste(refuse) landfill stabilizes as the refuse degrades. After years of biodegradation, the refuse in the landfill becomes stabilized and aged, which may vary with the local climate, humidity, and composition of refuse placed. In this work, it is found that the refuse with an age of over 8 years at Shanghai Refuse Landfill has been significantly stabilized and sufficiently aged and is thus suitable for excavation. The 8 year old aged refuse is mechanically screened, and the fine fractions of refuse(aged refuse) with a diameter less than 2 cm are then used as a biological absorbent for removal of both inorganic and organic phosphorus in livestock wastewater and prepared aqueous solution. It is proved that the aged refuse is very effective for the quantitative removal of both types of phosphorus. The absorption mechanism is proposed. It is considered that phosphorus is firstly absorbed onto the surface of the aged refuse and then used as a substrate for the growth of microorganisms which ultimately leave the aged refuse as sludge.

关键词： refuse phosphorus landfill livestock wastewater biological absorption

Nucleation for Lennard-Jones Fluid by Density Functional Theory

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Chinese Physics Letters 2005年第6期22卷 1378-1381页

作者：付东 SchoolofEnvironmentalScienceandEngineering NorthChinaElectricPowerUniversityBaoding071003

A non-mean field density functional theory is employed to investigate the vapour–liquid nucleation. The excess Helmholtz free energy functional is formulated in terms of a local density approximation for short ranged repulsion and a density-gradient expansion for long-ranged attractions. An analytical expression for the direct correlation function of a Lennard-Jones fluid is utilized to take into account the effect of long-ranged attractions on intermolecular correlations. With the predicted bulk properties and surface tension as input, the nucleation properties including density profile, work of formation and number of particles at the reduced temperatures T* = 0.694 and 0.741 are investigated. The obtained number of particles in the critical nucleus agrees well with the simulation data.

关键词： CNT DFT LJ

Natural organic matter(NOM) removal from surface water by coagulation

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Journal of Environmental Sciences 2005年第1期17卷 119-122页

作者： GAOBao-yu YUEQin-yan SchoolofEnvironmentalScienceandEngineering ShandongUniversityJinan250100China

Poly aluminum chloride sulfate(PACS) with different SO 2- 4/Al 3+ mole ratios and bacicity(γ) of 2 0 was synthesized using AlCl 3\56H\-2O, Al\-2(SO\-4)\-3\518H 2O and Na 2CO 3 as raw materials. The effect of SO 2- \-4/Al 3+ ratio on the performance of PACS for removal of natural organic matter(NOM) with humic rich actual water was examined. It was found that PACS with SO 2- \-4/Al 3+ mole ratio of 0.0664 achieved the best NOM removal results and was selected to investigate its performance in comparison with PAC, FeCl 3 and alum(Al 2 (SO 4) 3·18H 2O). The experimental results showed that the optimum NOM removals were achieved at pH 5.0\_8.2 and the dose of about 5 0 mg/L as Al both for the selected PACS and PAC, at pH 5 0\_6 0 and the dose of about 7 0 mg/L as Fe for FeCl 3, and at pH 5 0\_7 0 and the dose of about 7 0 mg/L as Al for alum, respectively. At the optimum conditions, the selected PACS achieved the best NOM removal result, followed by PAC, FeCl 3, and then alum. The concentration of residual aluminum in treated water by the selected PACS and PAC under the optimum coagulant conditions was approximately 115 μg/L, which can completely comply with the regulated limits.

关键词： coagulation humic rich water NOM removal residual aluminum

Investigation of the Phase Equilibria and Interfacial Properties for Non-polar Fluids

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Chinese Journal of Chemistry 2005年第4期23卷 386-392页

作者：付东赵毅 SchoolofEnvironmentalScienceandEngineering NorthChinaElectricPowerUniversityBaodingHebei071003China

A self‐consistent density‐functional theory (DFT) was applied to investigate the phase behavior and interfacial properties of non‐polar fluids. For the bulk phases, the theory was reduced to the statistical associating fluid theory (SAFT) that provides accurate descriptions of vapor‐liquid phase diagrams below the critical region. The phase diagrams in the critical region were corrected by the renormalization group theory (RGT). The density profile in the surface was obtained by minimizing the grand potential. With the same set of molecular parameters, both the phase equilibria and the interfacial properties of non‐polar fluids were investigated satisfactorily.

关键词： density functional theory renormalization group theory phase equilibria surface tension non‐polar fluid

Effect of inhibitors on macroscopical oxidation kinetics of calcium sulfite

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Journal of Environmental Sciences 2005年第3期17卷 483-487页

作者： ZHAOYi WANGLi-dong WANGXiao-ming LIQiang-wei XUPei-yao SchoolofEnvironmentalScienceandEngineering NorthChinaElectricPowerUniversityBaoding071003China StatePowerEnvironmentalProtectionResearchInstitute Nanjing210031China

In the presence of inhibitors, the macroscopical oxidation kinetics of calcium sulfite, the main byproduct in wet limestone scrubbing, was studied for the first time by adding different inhibitors and varying pH, concentration of calcium sulfite, oxygen partial pressure, concentration of inhibitors and temperature. The mathematical model about the general oxidation reaction was established, which was controlled by three steps involving dissolution of calcium sulfite, mass transfer of oxygen and chemical reaction in the solution. It was concluded that the general reaction was controlled by mass transfer of oxygen under uncatalyzed conditions, while it was controlled by dissolution of calcium sulfite after adding three kinds of inhibitors. Thus, the theory was provided for investigating the mechanism and oxidation kinetics of sulfite. The beneficial references were also supplied for design of oxidation technics in the wet limestone scrubbing.

关键词： calcium sulfite macroscopical oxidation kinetics inhibitor

Rice From Mercury Contaminated Areas in Guizhou Province Induces c-jun Expression in Rat Brain

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Biomedical and Environmental Sciences 2005年第2期18卷 96-102页

作者： JIN-PINGCHENG WEN-HUAWANG LI-YAQU JIN-PINGJIA MINZHENG XIU-LINGJI TAOYUAN SchoolofEnvironmentalScienceandEngineering ShanghaiJiaotongUniversityShanghai200240China GuizhournstituteforEnvironmentalProtection GuiyangGuizhou550002China

Objective Mercury (Hg), as one of the priority pollutants and also a hot topic of frontier environmental research in many countries, has been paid higher attention in the world since the middle of the last century. Guizhou Province (at N24°30'-29°13', E103°1'-109°30', 1100 m above the sea level, with subtropical humid climate) in southwest China is an important mercury production center. It has been found that the mercury content in most media of aquatics, soil, atmosphere and in biomass of corns, plants and animals, is higher than the national standard.The present study aims to explore the influence of mercury pollution on the health of local citizens. Methods The effect of rice from two mercury polluted experimental plots of Guizhou Province on the expression of c-jun mRNA in rat brain and c-jun protein in cortex, hippocampus and ependyma was observed using reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemical methods. Results The results showed that the mercury polluted rice induced expression of c-jun mRNA and its protein significantly. Selenium can reduce Hg uptake, an antagonism between selenium and mercury on the expression of c-jun mRNA and c-jun protein. Conclusion c-jun participates in the toxicity process of brain injury by mercury polluted rice, the expression of c-jun mRNA in brain, and c-jun protein in rat cortex and hippocampus can predict neurotoxicity of mercury polluted rice. People should be advised to be cautious in eating any kind of Hg-polluted foods. To reveal the relationship between c-jun induction and apoptosis, further examinations are required.[第一段]

关键词： Guizhou Mercury polluted rice c-jun Gene expression Early prediction Exposure