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171.
A self-designed experimental device was employed to simulate the pyrolytic dismantling process of selected electronic wastes(E-wastes), including printed wiring boards(PWBs)and plastic casings. The generated particulate matter(PM) of different particle sizes, carbon monoxide(CO) and carbon dioxide(CO_2) were determined, and the corresponding emission factors(EFs) were estimated. Finer particles with particle sizes of 0.4–2.1 μm accounted for78.9% and 89.3% of PM emitted by the pyrolytic processing of PWBs and plastic casings,respectively, and the corresponding EFs were 9.68 ± 4.81 and 18.49 ± 7.2 g/kg, respectively.The EFs of CO and CO_2 from PWBs and plastic casings were 55.9 ± 26.9 and 1182 ± 439 g/kg,and 133.6 ± 34.6 and 2827 ± 276 g/kg, respectively. Compared with other emission sources,such as coal, biomass, and traffic exhaust, the EFs of E-wastes were relatively higher,especially for PM. There were significant positive correlations(p 0.05) of the initial contents of carbon and nitrogen in PWBs with the related EFs of PM, CO, and CO_2, while the correlations for plastic casings were insignificant. The EFs of CO of PWBs were significantly positively correlated with the corresponding EFs of PM and the parent polycyclic aromatic hydrocarbons(PAHs); however, the same result was not observed for plastic casings. 相似文献
172.
Guoying Wang Shiming Ji Xiuli Niu Haoqi Tian Yanrong Liu Zhong Xie Chao Liu Yucan Dong Ying Su Jianglei Yu Gaofeng Shi Xuefu Chen Lan Li Peng Zhang 《环境科学学报(英文版)》2019,31(7):205-213
Atmospheric particulate pollution in China has attracted much public attention. Occasionally, the particle number concentration increases sharply in a short time period, which is defined as a “particulate matter explosive increase”. Heavy particulate matter pollution not only reduces visibility but also has an adverse effect on human health. Hence, there is an urgent need to discover the causes of particulate matter explosive increase. During this campaign, the particle number concentration and free radicals were measured at a tall building on the campus of Lanzhou University of Technology. Additionally, we examined a series of chemicals to reproduce the observed particulate matter explosive increase in a smog chamber to determine its potential factors. Then, we analyzed the mechanism of particulate matter explosive increase in the presence of free radicals. We found that, among the potential inorganic and organic sources analyzed, a mixture of organic and SO2 in the research region had a major effect on particulate matter explosive increase. Moreover, free radical oxidation has a large effect, especially in the formation of organic particulates. 相似文献
173.
M. M. Turchetto A. Boldrin S. Rabitti F. Acri A. Comaschi 《Chemistry and Ecology》2013,29(1-2):127-141
During four oceanographic cruises carried out in June 1996, February and June 1997, and February 1998, particulate matter characteristics and short-term downward fluxes measured with drifting sediment traps were studied in two areas of the Adriatic Sea. The investigated areas were located one south of the Po River delta, and the other in the central Adriatic between Pesaro and Ancona. In each area, a frontal system was detected and two stations inside and outside the front, i.e . in coastal and offshore areas, were selected. The particulate and dissolved matter revealed a higher concentration in the coastal areas with the highest values in the central Adriatic coastal zone in both February surveys. Total mass fluxes ranged within two orders of magnitude from 11 to 3139 r mg m d in the northern area and similarly from 20 to 3864 r mg r m r d in the southern one, with higher values in the coastal stations. The organic carbon accounted for 3-30% of total flux in the northern coastal station with higher values in June, whereas at the offshore station it ranged from 6 to 39% in summer, decreasing to values lower than 10% in February. In the southern zone the organic carbon content was less than 2% in winter and from 3 to 33% in summer. The organic carbon fluxes (1-82 and 6-71 r mg C m d in the northern and southern area) were comparable with others measured with drifting sediment traps in the same area, though much lower with respect to those measured with long-term moored sediment traps. The export of organic carbon from the photic layer (expressed as the percentage of primary production) in the northern area was less than 10% at the coastal station, reaching a maximum of 12% in the offshore area. In the central Adriatic area it was greater, with values reaching up to 66% at the coastal station in June 1996. The organic carbon loss via sedimentation from the POC pool was low ( i.e. <1.5% per day) at both stations in the northern zone, while in the southern area the export was generally greater, exceeding 10% in the offshore area. 相似文献
174.
Triboelectric charging of powders during pneumatic transport can lead to hazardous spark discharges. In this study, the charging process was studied numerically by means of large eddy simulations. A range of design parameters was then analyzed statistically applying the Design of Experiments methodology. It is shown that the electric charge of the powder can be significantly decreased by reducing the conveying air velocity. Furthermore, the usage of pipes of a larger diameter and the application of higher solid mass flow rates also reduce the powder charge. 相似文献
175.
A Dual Fuel (LNG-Diesel) system can be applied to heavy-duty diesel trucks for achieving environmental benefits in comparison to existing diesel vehicles. Because of lack of reports about risk assessment of this technology, we performed a qualitative assessment based on a framework of some literature techniques for risk identification, analysis and evaluation. After constructing a Reliability Block Diagram (RBD) to establish the context, we conducted bow-tie analysis, Fault Tree Analysis (FTA), Failure Mode and Effects Analysis (FMEA), likelihood and consequence analysis, and used a risk matrix. We applied these methods and techniques qualitatively to identify causes (e.g. collisions), critical events (e.g. releases of natural gas), related consequences (e.g. fires and explosions), and different possible pathways from a specific cause to its consequence, and to assess some negative accident scenarios related to use and parking of the vehicle. The bow-tie analysis also allowed to make explicit barriers and controls that prevent critical events and/or mitigate consequences. Therefore, we identified a set of safety measures, including design, technical, management, and emergency actions, which shall be implemented in each step of the system's life cycle.Our risk assessment showed that the risk level of the Dual Fuel (LNG-Diesel) system is similar to the risk level of a traditional diesel system. Future research will overcome current lack of data and, therefore, permit a quantitative rating of the risk of the Dual Fuel (LNG-Diesel) system. 相似文献
176.
Daijun ZHANG Cui BAI Ting TANG Qing YANG 《Frontiers of Environmental Science & Engineering》2011,5(2):291-297
Shortcut nitrification-denitrification, anaerobic ammonium oxidation (ANAMMOX), and methanogenesis have been successfully coupled in an Expanded Granular Sludge Bed-Biological Aerated Filter (EGSB-BAF) integrated system. As fed different synthetic wastewater with chemical oxygen demand (COD) of 300–1200 mg·L-1 and N H 4 + - N of 30–120 mg·L-1 at the outer recycle ratio of 200%, the influence of influent on ANAMMOX in the integrated system was investigated in this paper. The experimental results showed that higher COD concentration caused an increase in denitrification and methanogenesis but a decrease in ANAMMOX; however, when an influent with the low concentration of COD was used, the opposite changes could be observed. Higher influent N H 4 + - N concentration favored ANAMMOX when the COD concentration of influent was fixed. Therefore, low C O D / N H 4 + - N ratio would decrease competition for nitrite between ANAMMOX and denitrification, which was favorable for reducing the negative effect of organic COD on ANAMMOX. The good performance of the integrated system indicated that the bacterial community of denitrification, ANAMMOX, and methanogenesis could be dynamically maintained in the sludge of EGSB reactor for a certain range of influent. 相似文献
177.
Mohammed Rasheed Christian Wild Carin Jantzen Mohammed Badran 《Chemistry and Ecology》2013,29(1):13-20
In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O2 fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O2 and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O2 ratios were 4.3–28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2–1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity. 相似文献
178.
179.
HPF(高通数字滤波器)的电网谐波检测技术的研究与应用 总被引:1,自引:0,他引:1
为有效地消除电力谐波污染、确保电网运行安全,必须采用有源电力滤波技术;为改善有源电力滤波器的性能,必须采取先进的谐波检测方法、高效的逆变技术。笔者在研究有源电力滤波技术的基础上,对有源电力滤波的关键技术即谐波检测与分离技术,进行了探讨和深入研究,给出了一种HPF(高通数字滤波器)的谐波检测与分离方法,进行了理论验算,利用MATLAB仿真结果对该检测技术进行实验研究。仿真和实验结果表明:该法比常用的LPF(低通数字滤波器LowPassDigitalFilter)的谐波检测分离方法具有更好的检测实时性;在电网电压有畸变时也能达到很高的检测精度;该检测技术应用于混合有源电力滤波器后能大大改善滤波性能。 相似文献
180.
Potential of the Conservation Reserve Program to control agricultural surface water pollution 总被引:1,自引:0,他引:1
Christopher L. Lant 《Environmental management》1991,15(4):507-518
The Conservation Reserve Program (CRP), initiated by the Conservation Title of the Food Security Act of 1985, is the primary
federal program to control nonpointsource pollution in agricultural watersheds of the United States. However, the program
is designed primarily to reduce soil erosion rather than to retire croplands in a manner optimal for controlling runoff of
sediment and associated pollutants. This study estimates potential enrollment of streamside and floodplain croplands in this
ten-year retirement program in order to gauge the potential of the CRP as a water-quality improvement policy. A contingent
choice survey design was employed in Fayette County, Illinois, to demonstrate that there is substantial potential for retirement
of streamside and floodplain croplands in the CRP. Enrollments in each program climb from less than 6% to over 83% of eligible
croplands as the annual rental rate is increased from $20 to $200/acre. Potential retirement of streamside and floodplain
croplands declines, however, if tree planting, drainage removal, or a 20-year contract are required. The potential of a CRP-based
water-quality program to improve water quality and aquatic ecosystems in agricultural watersheds is thus substantial but constrained
by the economic trade-offs that farmers make between crop production and conservation incentives in determining the use of
their riparian lands. 相似文献