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91.
Soman is one of the most toxic nerve agents of the known chemical warfare agents. There is actually few knowledge on the behavior of soman in the event of an environmental contamination. It is in particular unknown whether soman remains on a given surface, evaporates into air, or degrades. Here, we studied the evaporation of soman deposited on silica sand using a laboratory-sized wind tunnel, thermal desorption, and gas chromatography. We also investigated the degradation of soman on silica sand by 31phosphorus solid state magic angle spinning nuclear magnetic resonance and gas chromatography–mass spectrometry. Results show that a drop of soman on silica sand spreads laterally while evaporating. The maximum vapor concentration was found when the spreading of the soman drop was maximum on the surface. Simultaneously, soman was absorbed gradually into the pore of sand and degraded to O-pinacolyl-methylphosphonic acid following a pseudo-first-order rate reaction over weeks. To our best knowledge, this is the first report on the fate of soman in a sandy environment. 相似文献
92.
The process involving the combination of powdered activated carbon (PAC) and biomass in the aeration basin of conventional continuous‐flow activated sludge system, known as the PACT process, has proven to be effective for treating toxic pollutants present in industrial wastewaters. In view of the many advantages of sequencing batch reactors (SBR) operationally, the objective of this study is to evaluate the PACT process under SBR operation to treat wastewater containing Acid Blue 25 (AR) and Basic Yellow 2 dyes (BR). The SBR systems were operated with FILL, REACT, SETTLE and DRAW periods in the ratio of 0.25:3.75: 1.0:1.0 for a cycle time of 6 h. The average COD and AR removal efficiencies were 89% and 93%, respectively with PAC addition compared to 76% and 7%, respectively, without PAC addition. In the case of BR, the average removal efficiencies of COD and dye increased from 52% and 9% to 90% and 93%, respectively, with PAC addition. Kinetic study conducted for the REACT period showed that both dyes exhibited a very pronounced inhibitory effect on the activities of the microorganisms. The addition of PAC was capable of reducing the inhibitory effect of only BR but not AR on the microorganisms. 相似文献
93.
For the abutment bed scour to reach its equilibrium state, a long flow time is needed. Hence, the employment of usual strategy of simulating such scouring event using the 3D numerical model is very time consuming and less practical. In order to develop an applicable model to consider temporally long abutment scouring process, this study modifies the common approach of 2D shallow water equations (SWEs) model to account for the sediment transport and turbulence, and provides a realistic approach to simulate the long scouring process to reach the full scour equilibrium. Due to the high demand of the 2D SWEs numerical scheme performance to simulate the abutment bed scouring, a recently proposed surface gradient upwind method (SGUM) was also used to improve the simulation of the numerical source terms. The abutment scour experiments of this study were conducted using the facility of Hydraulics Laboratory at Nanyang Technological University, Singapore to compare with the presented 2D SGUM–SWEs model. Fifteen experiments were conducted with their scouring flow durations vary from 46 to 546 h. The comparison shows that the 2D SGUM–SWEs model gives good representation to the experimental results with the practical advantage. 相似文献
94.
Jun-Wei Lim Poh-Eng Lim Chye-Eng Seng Rohana Adnan 《Environmental science and pollution research international》2014,21(1):485-494
The feasibility of using dried attached-growth biomass from the polyurethane (PU) foam cubes as a solid carbon source to enhance the denitrification process in the intermittently aerated moving bed sequencing batch reactor (IA-MBSBR) during the treatment of low COD/N containing wastewater was investigated. By packing the IA-MBSBR with 8 % (v/v) of 8-mL PU foam cubes saturated with dried attached-growth biomass, total nitrogen removal efficiency of 80 % could be achieved for 10 consecutive cycles of operation when the intermittent aeration strategy of consecutive 1 h of aeration followed by 2 h of non-aeration period during the REACT period of the IA-MBSBR was adopted. Negligible release of ammonium nitrogen (NH4 +–N) and slow-release of COD from the dried biomass would ensure that the use of this solid carbon source would not further burden the treatment system. The slow-releasing COD was found to have no effect in promoting the assimilation process and would also allow the carbon source to be used for many cycles of operation. The ‘carbon-spent’ PU foam cubes could be reused by merely drying at 60 °C at the end of the operational mode. Thus, the dried attached-growth biomass formed on the PU foam cubes could be exploited as an alternative solid carbon source for the enhancement of denitrification process in the IA-MBSBR. 相似文献
95.
96.
Junghwan Kim Jinkyung Kim Younghee Lee Wonsub Lim Il Moon 《Journal of Loss Prevention in the Process Industries》2009,22(6):1039-1043
This study develops a modified method of TRIZ to improve safety in chemical process design. This method is modified by the theory of TRIZ, which is inventive problem solving theory, for retrofit design of chemical process considering safety.The original TRIZ is difficult to access to chemical process safety due to inapplicability and ambiguity of terminology in classification of these parameters. It is necessary to be modified TRIZ for chemical process safety. This study reorganized thirty-nine parameters of the TRIZ into six categories such as mechanic, operator, process upset, design, natural hazard and material. The modified TRIZ is tested to jacketed reactor and polyethylene reactor. 相似文献
97.
The photocatalytic removal of humic acid (HA) using TiO2 under UVA irradiation was examined by monitoring changes in the UV254 absorbance, dissolved organic carbon (DOC) concentration, apparent molecular weight distribution, and trihalomethane formation potentials (THMFPs) over treatment time. A resin fractionation technique in which the samples were fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids, hydrophilic charged (CHA) and hydrophilic neutral (NEU) was also employed to elucidate the changes in the chemical nature of the HA components during treatment. The UVA/TiO2 process was found to be effective in removing more than 80% DOC and 90% UV254 absorbance. The THMFPs of samples were decreased to below 20 μg l−1 after treatments, which demonstrate the potential to meet increasingly stringent regulatory level of trihalomethanes in water. Resin fractionation analysis showed that the VHA fraction was decreased considerably as a result of photocatalytic treatments, forming CHA intermediates which were further degraded with increased irradiation time. The NEU fraction, which comprised of non-UV-absorbing low molecular weight compounds, was found to be the most persistent component. 相似文献
98.
Tae‐Yeol Kim Debra L. Shapiro Karl Aquino Vivien K. G. Lim Rebecca J. Bennett 《组织行为杂志》2008,29(3):415-433
This study examined the effects of workplace offenders' characteristics and offense‐type on victims' reactions. Responses from 352 employed graduate students in the U.S. and South Korea to a hypothetical offense incident revealed that employees from the U.S. and Korea differ in their expressed desirability of avoiding, seeking revenge against, and reconciling with an offending coworker depending on the offenders' similarity/dissimilarity to the victim and on the type of offense. As expected, Koreans (but not U.S. Americans) were more likely to avoid and to seek revenge on a coworker whose offensive remark was group‐ rather than personally‐directed. In addition, Koreans were most motivated to reconcile when an offensive remark came from a similar rather than dissimilar coworker and when the offense targeted them personally (not their group). However, U.S. Americans were most motivated to reconcile when an offensive remark came from a similar rather than dissimilar other and when the offense targeted their group (not them personally). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
99.
100.
Mark J. Perri Yong B. Lim Sybil P. Seitzinger Barbara J. Turpin 《Atmospheric environment (Oxford, England : 1994)》2010,44(21-22):2658-2664
Secondary organic aerosol (SOA) formation is enhanced on acidic seed particles; SOA also forms during cloud processing reactions where acidic sulfate is prevalent. Recently several studies have focused on the identification of organosulfates in atmospheric aerosols or smog chamber experiments, and upon the mechanism of formation for these products. We identify several organosulfate products formed during the laboratory OH radical oxidation of dilute aqueous glycolaldehyde in the presence of sulfuric acid. We propose a radical–radical reaction mechanism as being consistent with formation of these products under our experimental conditions. Using a kinetics model we estimate that organosulfates account for less than 1% of organic matter formed from these precursors during cloud processing. However, in wet acidic aerosols, where precursors are highly concentrated and acidic sulfate makes up close to half of the aerosol mass, this radical–radical reaction could account for significant organosulfate production. 相似文献