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31.
Joo-Youp Lee Yuhong Ju Sang-Sup Lee Tim C. Keener Rajender S. Varma 《Water, Air, & Soil Pollution: Focus》2008,8(3-4):333-341
The authors have successfully developed novel efficient and cost-effective sorbent and oxidant for removing mercury from power
plant flue gases. These sorbent and oxidant offer great promise for controlling mercury emissions from coal-fired power plants
burning a wide range of coals including bituminous, sub-bituminous, and lignite coals. A preliminary analysis from the bench-scale
test results shows that this new sorbent will be thermally more stable and cost-effective in comparison with any promoted
mercury sorbents currently available in the marketplace. In addition to the sorbent, an excellent elemental mercury (Hg(0))
oxidant has also been developed, and will enable coal-fired power plants equipped with wet scrubbers to simultaneously control
their mercury emissions as well as their sulfur oxides emissions. This will work by converting all elemental mercury to an
oxidized form which will be removed by the wet scrubber. This will result in significant cost savings for mercury emissions
control to the atmosphere, and will help in keeping electric costs low. The sorbent and oxidant will benefit from the utilization
of a waste stream from the printed circuit board (PCB) industry, and would thus be environmentally beneficial to both of the
utility and electronics industries. The sorbent also demonstrated thermal stability up to 350°C, suggesting a possibility
of an application in pulverized coal-fired power plants equipped with hot-side electrostatic precipitators and coal gasification
plants. 相似文献
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We assayed maternal serum samples from 134 black and 268 white women from 16 to 18 weeks of gestation for intact human chorionic gonadotropin (hCG), and unconjugated oestriol (uE3). Serum from women with high ( ⩾ 2·5 MOMs) or low (risk for Down syndrome ⩾ 1/365) maternal serum alpha-fetoprotein (MSAFP) levels were excluded. After correcting for maternal weight, we found that median hCG levels were 16 per cent higher in black women but uE3 levels were not significantly different. These results confirm three other studies for hCG and one study for uE3. Corrections are recommended for both maternal serum hCG and AFP before calculating the risk for Down syndrome in black women. 相似文献
34.
A technical and economic comparison of biofiltration and wet chemical oxidation (scrubbing) for odor control at wastewater treatment plants 总被引:2,自引:0,他引:2
Li Gao Tim C. Keener Lian Zhuang Kaniz F. Siddiqui 《Environmental Engineering and Policy》2001,2(4):203-212
An economic and technical comparison of two odor control systems, a biofilter and a chemical wet scrubber, was conducted over a 1-year time period at a large municipal wastewater treatment plant. The biofilter system was designed to remove hydrogen sulfide gas and other oxidizable sewage odors from four covered gravity sludge thickeners, a gravity sludge thickener effluent channel and an influent splitter box for the gravity sludge thickeners. The sodium hypochlorite/sodium hydroxide wet scrubber was designed to control hydrogen sulfide gas and other oxidizable sewage odors from the covered primary settling tanks, influent distribution channels and effluent channel, and the mixing tank effluent channel. The technical comparison comprised their overall removal rates and efficiencies based on inlet H2S concentrations and other operating variables. The economic comparison was designed to provide the cost per cubic meter of H2S removed for each system. Influent and effluent gas samples were collected on a weekly basis. H2S concentration levels were determined through the use of gas chromatography with a flame photometric detector. The results showed that the H2S inlet gas concentration has a seasonal change with a maximum value occurring in August and September. The effluent H2S concentration was lower than 2 ppmv for both systems for most of the samples. The efficiency for both the biofilter and wet scrubber was above 95%, and was related to the operating and ambient conditions. The economic comparison revealed that the actual unit cost for the biofilter was higher than for the wet scrubber (U.S.160 /m < SUP > 3 < /SUP > H < SUB > 2 < /SUB > S removed versus U.S.160 /m3 H2S removed versus U.S.131 /m3 H2S removed). For both the biofilter and the wet scrubber, the investment costs are affected by the size/scale of the system, the design flow and other factors. For these systems, the mulch change costs, chemical usage costs, maintenance costs and power usage costs were mainly dependent on the actual odor gas loadings which showed substantial seasonal fluctuations as a function of the seasonal temperature. The worst case conditions reported here indicate that the H2S concentrations generated during the summer months should be used to determine the design load. 相似文献
35.
This study focuses on quantitative differences in mercury bioaccumulation based on the sex of the specimen. The species of interest is an herbivorous, terrestrial insect. Male and female periodical cicadas (genus: Magicicada) analyzed using combustion atomic absorption spectrophotometry exhibit different levels of mercury bioaccumulation. The concentration of mercury in Magicicada cassini males was significantly higher than the concentration in females of the same species. 相似文献