Combustion characteristics of spent catalyst and paper sludge in an internally circulating fluidized-bed combustor

Combustion of spent vacuum residue hydrodesulfurization catalyst and incineration of paper sludge were carried out in thermo-gravimetric analyzer and an internally circulating fluidized-bed (ICFB) reactor. From the thermo-gravimetric analyzer-differential thermo-gravimetric curves, the pre-exponential factors and activation energies are determined at the divided temperature regions, and the thermo-gravimetric analysis patterns can be predicted by the kinetic equations. The effects of bed temperature, gas velocity in the draft tube and annulus, solid circulation rate, and waste feed rate on combustion efficiency of the wastes have been determined in an ICFB from the experiments and the model studies. The ICFB combustor exhibits uniform temperature distribution along the bed height with high combustion efficiency (>90%). The combustion efficiency increases with increasing reaction temperature, gas velocity in the annulus region, and solid circulation rate and decreases with increasing waste feed rate and gas velocity in the draft tube. The simulated data from the kinetic equation and the hydrodynamic models predict the experimental data reasonably well.     

Evaluation of the relationship between two different methods for enumeration fecal indicator bacteria： Colony-forming unit and most probable number

Most probable number (MPN) and colony-forming unit (CFU) estimates of fecal indicator bacteria (FIB) concentration are common measures of water quality in aquatic environments. Thus, FIB intensively monitored in Yeongsan Watershed in an attempt to compare two di erent methods and to develop a statistical model to convert from CFU to MPN estimates or vice versa. As a result, the significant di erence was found in the MPN and CFU estimates. The enumerated Escherichia coli concentrations in MPN are greater than those in CFU, except for the measurement in winter. Especially in fall, E. coli concentrations in MPN are one order of magnitude greater than that in CFU. Contrarily, enterococci bacteria in MPN are lower than those in CFU. However, in general, a strongly positive relationship are found between MPN and CFU estimates. Therefore, the statistical models were developed, and showed the reasonable converting FIB concentrations from CFU estimates to MPN estimates. We expect this study will provide preliminary information towards future research on whether di erent analysis methods may result in di erent water quality standard violation frequencies for the same water sample.     

Evaluation on the applicability of dry processed bottom ash as lightweight aggregate for construction fields

Currently, wet bottom ash is not sufficiently utilized due to its content of unburned coal, chloride and moisture. In contrast, bottom ash discharged from the recently introduced dry process spends a longer time on the clinker conveyer in the lower part of the boiler and consequently contains a significantly smaller amount of unburned coal. Consequently, it has high potential for use as a lightweight aggregate for construction material because of properties such as high porosity, low unburned coal content, non-chloride, and non-moisture. However, it is not frequently used for construction because the ash particle has a flat and thin shape, coarse surface and unfavorable structural strength. Against this backdrop, this study has conducted a range of experiments to identify the shapes, structure, density, absorption, percentage of floating particles, unit volume weight, solid volume, characteristics of air bubbles and micro pores, crushing strength of bottom ash, and the following results were observed. Though the dry bottom ash has sharp and angular edges, its flat and thin shapes lead to vulnerable structures. Dry bottom ash of the size of 0.6 mm or larger has 50–60 % of the total pore rate and 30–50 % of the closed pore rate. Considering these qualities, by removing the relatively fragile surface parts and making the particles more globular, dry bottom ash can be used as a lightweight aggregate for construction field having outstanding performance in terms of light weight and insulation.     

Phylogeography of the seaweed Ishige okamurae (Phaeophyceae): evidence for glacial refugia in the northwest Pacific region

Although benthic marine algae are essential components of marine coastal systems that have been influenced profoundly by past and present climate change, our knowledge of seaweed phylogeography is limited. The brown alga Ishige okamurae Yendo occurs in the northwest Pacific, where it occupies a characteristic belt in the exposed intertidal zone. To understand the patterns of genetic diversity and the evolutionary history of this species, we analyzed mitochondrial cox3 from 14 populations (221 individuals) throughout its range. The 17 haplotypes found in this study formed five distinct clades, indicating significant genetic structure. The high differentiation and number of unique (private) haplotypes may result from the recolonization of the species from glacial refugia. Three putative refugia, each with high genetic diversity, were identified: southern Korea (including Jeju Island), northern Taiwan, and central Pacific Japan. Recolonization of I. okamurae was probably determined by ocean currents and changes in sea level during the last glacial period.     

Charge reduction on polypropylene granules and suppression of incendiary electrostatic discharges by using a novel AC electrostatic ionizer

As a method to prevent or mitigate electrostatic charge and/or discharges, we have developed a novel AC electrostatic ionizer. In this study, we evaluated experimentally the practical version of the novel AC electrostatic ionizer with a modeling test system and a pneumatic powder transport facility. In addition, electrostatic discharges generated inside a silo while loading polypropylene (PP, 3 mm) granules were observed visually with/without the novel AC ionizer. The specific charge was clearly decreased with the novel AC electrostatic ionizer. The specific charge obtained with the four arranged AC electrostatic ionizers used was approximately one eighth of that without the AC ionizer. The incendiary bulk surface discharges completely died out inside the silo by using the four arranged ionizers.     

沙尘暴事件中大气颗粒物化学组分的浓度变化和硫酸盐的形成

应用电感耦合等离子体原子发射光谱、质谱和离子色谱分析了2002年3月28日-4月8日在山东长岛县采集的共11对粗、细大气颗粒物样品的化学组成,探讨4月6-8日沙尘暴事件中大气颗粒物化学组分的变化和硫酸盐的形成.沙尘暴事件应区分前锋和后续部分,前锋与大气中各种污染物相互作用,具有硫富集的特征.后续部分较好地保持了长距离传输风沙尘本身的特征.硫酸盐的形成机理可能是多相氧化而不是简单的酸碱中和.硫酸铵是首先生成的含硫物种,这是细颗粒主导的形成过程.硫酸铵逐渐转化为其他硫酸盐,硫的成分也逐渐向粗颗粒转移.在沙尘暴事件中含硫污染物不但有一个从气相向颗粒物转变的过程,也有一个从细颗粒向粗颗粒转化的过程.      

Halide salts accelerate degradation of high explosives by zerovalent iron

Zerovalent iron (Fe(0), ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe(0) (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24h also restored ZVI reactivity, resulting in complete degradation within 8h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl(-) and Br(-) was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br(-) was present in solution.     

First-trimester screening for Down syndrome; the role of nasal bone assessment in the Korean population

Objectives The aim of this study was to evaluate the role of nasal bone assessment in first-trimester screening for Down syndrome (DS) in the Korean population. Methods From July 2004 to March 2006, we prospectively evaluated the fetal nasal bones at 11–14 weeks' gestation in the Korean population. Results A successful evaluation was possible in 6490 of 6787 fetuses (95.6%). Absent, hypoechoic, and short nasal bones were seen in 4 (26.7%), 4 (26.7%), and 1 (6.7%) of 15 fetuses with DS, respectively, whereas in 5 (0.1%), 11 (0.2%), and 246 (3.8%) of 6456 normal fetuses. The incidence of absent and hypoechoic nasal bone showed significant differences between normal fetuses and fetuses with DS (P < 0.0005, both). Screening for DS using an absent or hypoechoic nasal bone resulted in a sensitivity of 53.3%, a specificity of 99.8%, a positive likelihood ratio of 215.2, and a negative likelihood ratio of 0.5. Conclusion Our study showed that nasal bone abnormality at 11–14 weeks of gestation had a high association with DS in the Korean population. This suggests that nasal bone assessment can be used to supplement the current first-trimester screening for DS in the Korean population. Copyright © 2007 John Wiley & Sons, Ltd.     

Bioleaching of zinc and copper from anaerobically digested swine manure: effect of sulfur levels and solids contents.

Anaerobically digested swine manure (ADSM) generally contains high concentrations of zinc (Zn) and copper (Cu). These metals levels exceed the land application regulations of municipal biosolids of many European countries and are on the borderline of exceptional quality in the U.S. Environmental Protection Agency (U.S. EPA) 40 CFR part 503 standards. From this perspective, a series of batch tests were conducted to evaluate the feasibility of bioleaching of Zn and Cu from ADSM so that the produced biosolids could safely be applied to land. The effect of different substrate levels (sulfur) and total solids content (as high as 9%) on metal solubilization was investigated. The results showed that metal solubilization efficiency for both Zn and Cu declined significantly with an increase in total solids from 3 to 6% and then to 9% at the same substrate level. Metal solubilization increased proportionately with increases in substrate concentration up to 6% of total solids content. However, at 9% total solids content, metal solubilization was insignificant at all substrate levels tested. At a 6% total solids level and 10 000 mg/L of substrate, 94% of Zn and 72% of Cu were solubilized. Bioleaching was also found to be effective in destruction of pathogens with approximately 2.5 log-scale reduction. The residual biosolid was found to meet the Class A biosolids standands of U.S. EPA 40 CFR part 503.     

Multilateral energy lending and urban bias in autocracies: promoting fossil fuels

Energy demand is growing rapidly across the world, and international funding agencies like the World Bank have responded by emphasizing energy in their project portfolios. Some of these projects promote the use of fossil fuels, while others support cleaner forms of energy. For climate change mitigation, it is important to understand how international funders decide on the choice between fossil fuels and cleaner sources of energy. Examining the energy funding portfolios of the nine most important international funders for the years 2008-2011, we show that funding for fossil fuels has been concentrated in highly urbanized autocracies. Due to economies of scale, fossil fuels are suitable for generating heat and electricity for densely populated urban areas. Autocratic rulers are subject to urban bias in their policy formulation because the support of concentrated urban constituencies is key to an autocrat’s political survival, and in democracies environmental constituencies can effectively oppose fossil fuel projects.