Partitioning and removal of dioxin-like congeners in flue gases treated with activated carbon adsorption

Activated carbon adsorption is commonly used to control dioxin-like congener (PCDD/Fs and PCBs) emissions. Partitioning of PCDD/Fs and PCBs between vapor and solid phases and their removal efficiencies achieved with existing air pollution control devices (APCDs) at a large-scale municipal waste incinerator (MWI) and an industrial waste incinerator (IWI) are evaluated via intensive stack sampling and analysis. Those two facilities investigated are equipped with activated carbon injection (ACI) with bag filter (BF) and fixed activated carbon bed (FACB) as major PCDD/F control devices, respectively. Average PCDD/F and PCB concentrations of stack gas with ACI+BF as APCDs are 0.031 and 0.006ng-TEQ/Nm(3), and that achieved with FACB are 1.74 and 0.19ng-TEQ/Nm(3) in MWI and IWI, respectively. The results show that FACB could reduce vapor-phase PCDD/Fs and PCBs concentrations in flue gas, while the ACI+BF can effectively adsorb the vapor-phase dioxin-like congener and collect the solid-phase PCDD/Fs and PCBs in the meantime. Additionally, the results of the pilot-scale adsorption system (PAS) experimentation indicate that each gram activated carbon adsorbs 105-115ng-PCDD/Fs and each surface area (m(2)) of activated carbon adsorbs 10-25ng-PCDD/Fs. Based on the results of PAS experimentation, this study confirms that the surface area of mesopore+macropore (20-200A) of the activated carbon is a critical factor affecting PCDD/F adsorption capacity.     

Prediction for energy content of Taiwan municipal solid waste using multilayer perceptron neural networks

In the past decade, the treatment amount of municipal solid waste (MSW) by incineration has increased significantly in Taiwan. By year 2008, approximately 70% of the total MSW generated will be incinerated. The energy content (usually expressed by lower heating value [LHV]) of MSW is an important parameter for the selection of incinerator capacity. In this work, wastes from 55 sampling sites, including villages, towns, cities, and remote islands in the Taiwan area, were sampled and analyzed once a season from April 2002 to March 2003 to determine the waste characteristics. The LHV of MSW in Taiwan was predicted by the multilayer perceptron (MLP) neural networks model using the input parameters of elemental analysis and dry- or wet-base physical compositions. Although all three of the models predicted LHV values rather accurately, the elemental analysis model provided the most accurate prediction of LHV values. Additionally, the wet-base physical composition model was the easiest and most economical. Therefore, the waste treatment operators can choose the more appropriate analysis method considering situations themselves, such as time, equipment, technology, and cost.     

Thermal hazard accident investigation of hydrogen peroxide mixing with propanone employing calorimetric approaches

Hydrogen peroxide (H₂O₂), historically, due to its broad applications in the chemical industries, has caused many serious fires and explosions around the world. Its thermal hazards may also be incurred by an incompatible reaction with other chemicals, and a runaway reaction may be induced in the last stage. This study applied thermal analytical methods to explore the H₂O₂ leading to these accidents by incompatibility and to discuss what might be formed by the upset situations. Thermal hazard analysis contained a solvent, propanone (CH₃COCH₃, so-called acetone), which was deliberately selected to mix with H₂O₂ for investigating the degree of thermal hazard. Differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2) were employed to evaluate the thermal hazard of H₂O₂. The results indicated that H₂O₂ is highly hazardous while mixed with propanone, as a potential contaminant. The time to maximum rate (TMR) was used as emergency response time in the chemical industries. Therefore, TMR of H₂O₂ was calculated to be 70 min for runaway reaction (after T₀) and TMR of H₂O₂/propanone was discovered to be 27 min only. Fire and explosion hazards could be successfully lessened if the safety-related data are properly imbedded into manufacturing processes.     

用连续提取法研究芘在鱼鳃表面的结合形态

建立了研究鱼鳃表面芘的结合状态的四步连续提取方法．分别用H2O、CaCl2、CH3OH和n-C6H14+CH2Cl2(1:1, v/v)混合液提取经暴露的鱼鳃．操作定义的前3步分别提取松散附着在鳃表的鱼鳃黏液中的芘,紧密附着在鳃表的鱼鳃黏液中的芘以及直接吸着在鱼鳃表皮上的芘,第4步则用来提取鱼鳃组织吸收的芘．其提取的芘分别占总量的 4．0％、12．1％、45．2％和38．7％．经3 h暴露,进入鳃组织的芘仅为总测定量的三分之一强,因此大部分芘并未进入鳃组织．单独进行的五步CH3OH连续提取实验结果证明,CH3OH提取步骤能有效地解吸鳃表吸着的芘,但不会导致鳃组织中芘的释放．动态实验结果表明,黏液结合态芘在暴露1h左右即达到平衡,而鳃表吸着态和鳃组织吸收态芘在暴露3h内含量迅速上升,3 h后显著趋缓．     

Long-term temporal-spatial dynamics of marine coastal water quality in the Tolo Harbor, Hong Kong, China

IntroductionToloHarborislocatedinthenortheasternpartofHongKong .Itisanearlyland lockedwaterbodywithonlyonenarrowexittotheopenseaatMirsBay(Fig .1) .Itslengthandsurfaceareaareapproximately 15kmand 5 2km2 ,respectively .Theaveragedepthvariesfromlessthan10min…     

长江、嘉陵江(重庆段)源水有机提取物的类雌激素活性评价

为了解长江、嘉陵江(重庆段)源水有机提取物的类雌激素活性，分别于夏季和冬季采用GDX—120大孔树脂对位于城区上、中、下游5个断面长江、嘉陵江(重庆段)源水进行有机物的浓缩提取。用体外MCF—7细胞增殖试验检测有机提取物的类雌激素活性。结果显示，源水有机提取物均具有类雌激素活性。其类雌激素活性中、下游均高于上游，丰水期高于枯水期。     

介质特性对DBD降解苯的影响

为了提高介质阻挡放电(dielectric barrier discharge,DBD)等离子体的处理效率,研究了内外介质组成分别为:(1)石英 石英;(2)陶瓷 石英;(3)陶瓷 陶瓷这3种情况下苯的降解情况.试验结果表明,在处理低浓度含苯废气时,陶瓷 陶瓷效果最好;陶瓷(内管) 石英(外管)在处理高浓度含苯废气时显示出优势.通过对气相产物和固相结焦产物的分析验证了DBD能有效降解苯,降解产物不会带来新的污染.进一步分析了实验条件和介质材料的变化对DBD降解苯的影响机理.     

Particulate matter pollution in Kunshan High-Tech zone: Source apportionment with trace elements, plume evolution and its monitoring

Particulate matter(PM) in the Kunshan High-Tech zone is studied during a three-month campaign. PM and trace elements are measured by the online pollution monitoring, forecastwarning and source term retrieval system AS3. Hourly measured concentrations of PM_(10), PM_(2.5) and 16 trace elements in the PM_(2.5) section(Ca, Pb, Cu, Cl, V, Cr, Fe, Ti, Mn, Ni, Zn, Ga, As, Se, Sr, Ba)are focused. Source apportionment of trace elements by Positive Matrix Factorization modeling indicates that there are five major sources, including dust, industrial processing, traffic,combustion, and sea salt with contribution rate of 23.68%, 21.66%, 14.30%, 22.03%, and 6.89%,respectively. Prediction of plume dispersion from concrete plant and traffic emissions shows that PM_(10) pollution of concrete plant is three orders of magnitude more than that of the traffic. The influence range can extend to more than 3 km in 1 hr. Because the footprint of the industrial plumes is constantly moving according to the local meteorological conditions, the fixed monitoring sites scattered in a few hundred meters haven't captured the heaviest pollution plume at the local scale of a few km~2. As a more intensive monitoring network is not operationally possible, the use of online modeling gives accurate and quantitative information of plume location, which increases the spatial pollution monitoring capacity and improves the understanding of measurement data. These results indicate that the development of the AS3 system, which combines monitoring equipment and air pollution modeling systems, is beneficial to the real-time pollution monitoring in the industrial zone.     

基于保护的瓷窑型遗址绿化改造研究——以长沙铜官窑遗址为例

瓷窑型遗址由于其埋藏浅、需要恒温恒湿等特点,对绿化的要求与其它遗址不尽相同。基于保护为主的绿化改造是瓷窑型遗址保护的重要内容。文章以长沙铜官窑遗址为例,在分析了长沙铜官窑遗址的植被组成、绿化现状以及现有植被对遗址保护的利弊基础上,提出了基于保护为主的绿化改造总体设想、主要对策措施和技术模式,希望为中国瓷窑型遗址的绿化改造提供借鉴。     

纯氧曝气与空气曝气处理生活污水的效果比较

研究纯氧曝气与空气曝气对好氧装置处理生活污水效果以及对NH3和H2S产生量的影响。试验结果表明,与空气曝气相比,纯氧曝气的COD去除率高2.57%,NH3-N去除率高9.59%;处理7L相同体积的污水,空气曝气吹脱出的NH3是纯氧曝气的3.4倍,吹脱出的H2S平均值为12.99 ug,远大于纯氧曝气装置的0.38 ug。