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381.
以某污水处理厂运行4年多的旧盘式曝气器和同型号的新盘式曝气器为试验对象,对其氧转移速率进行了对比试验,结果表明新旧曝气盘氧转移速率均明显分为两个阶段,运行了4年的旧曝气盘微孔数量减少、微孔孔径增大、气泡数量减少、气泡尺寸增大,氧转移速率比新曝气盘降低了29.2%。因此,污水处理厂在日常运行管理中要做好曝气器的保养工作,及时清洗更换破损、堵塞的曝气器避免能耗浪费。 相似文献
382.
We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides(HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents(denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 μg/L to below 5 μg/L(the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201. 相似文献
383.
Soil organic carbon decomposition and carbon pools in temperate and sub-tropical forests in China 总被引:2,自引:0,他引:2
Yang L Pan J Shao Y Chen JM Ju WM Shi X Yuan S 《Journal of environmental management》2007,85(3):690-695
Decomposition of soil organic carbon (SOC) is a critical component of the global carbon cycle, and accurate estimates of SOC decomposition are important for forest carbon modeling and ultimately for decision making relative to carbon sequestration and mitigation of global climate change. We determined the major pools of SOC in four sites representing major forest types in China: temperate forests at Changbai Mountain (CBM) and Qilian Mountain (QLM), and sub-tropical forests at Yujiang (YJ) and Liping (LP) counties. A 90-day laboratory incubation was conducted to measure CO(2) evolution from forest soils from each site, and data from the incubation study were fitted to a three-pool first-order model that separated mineralizable soil organic carbon into active (C(a)), slow (C(s)) and resistant (C(r)) carbon pools. Results indicate that: (1) the rate of SOC decomposition in the sub-tropical zone was faster than that in the temperature zone, (2) The C(a) pool comprised approximately 1-3% of SOC with an average mean residence time (MRT) of 219 days. The C(s) pool comprised approximately 25-65% with an average MRT of 78 yr. The C(r) pool accounted for approximately 35-80% of SOC, (3) The YJ site in the sub-tropical zone had the greatest C(a) pool and the lowest MRT, while the QLM in the temperature zone had the greatest MRT for both the C(a) and C(s) pools. The results suggest a higher capacity for long-term C sequestration as SOC in temperature forests than in sub-tropical forests. 相似文献
384.
The integrated terrestrial ecosystem C-budget model (InTEC) developed by Chen and co-workers has been used successfully to predict carbon dynamics of forests in Canada. It was tested here for forest soil organic carbon (SOC) density of China's northern temperate zone and southern subtropical zone. The results show that the simulated SOC density is highly correlated and in broad agreement with observations in Liping and in Changbaishan, representing the southern subtropical zone and the northern temperate zone in China, respectively. SOC density ranged from 2.2 to 11.2 kg/m(2) in Liping and from 3.4 to 14.8 kg/m(2) in Changbaishan. The correlation coefficients (r(2)) are 0.63 (N=16) and 0.76 (N=14) between the simulated and measured data in Liping and Changbaishan, respectively. The SOC densities under different vegetation types in Liping decrease in the order of mixed forest, broadleaf forest, Chinese fir, couch grass, and Chinese redpine, and in Changbaishan in the order of mixed forest, silver fir, larch forest, and birch forest. 相似文献
385.
386.
燃煤锅炉NID脱硫系统的设计与应用 总被引:1,自引:0,他引:1
介绍了新型一体化NID半干法脱硫系统的工艺原理、NID技术特点、系统组成、设计参数和运行情况. 相似文献
387.
Accumulation of copper in brown rice and effect of copper on rice growth and grain yield in different rice cultivars 总被引:2,自引:0,他引:2
A pot experiment with 38 commonly cultured rice cultivars showed that the effect of Cu (100 mg kg(-1)) on rice growth, grain yield and accumulation of Cu in brown rice varied greatly with different cultivars. Although the average Cu concentration in brown rice of the 38 cultivars was significantly increased (P<0.01) compared with the control, in none of the cultivars did Cu concentration in brown rice exceed the maximum permissible limit of 10 mg Cu kg(-1). This suggests that rice grown in Cu-contaminated paddy soil (100 mg Cu kg(-1)) will not adversely affect human health through the food chain. Because of the significant negative correlation between grain weight and Cu concentration in brown rice with the soil Cu treatment, screening for cultivars with low Cu accumulation in brown rice and high grain yield for Cu-contaminated areas is feasible. The present research led to the recommendation of three such cultivars: Jiahua, Zhenxian 866, Zhe 733. The average grain yield under Cu treatment (100 mg Cu kg(-1) soil) was significantly (P<0.01) reduced compared with the control. The decreases or increases of grain yields mainly resulted from the combined effects of the panicles per pot, spikelets per panicle and filled spikelets per panicle under the soil Cu treatment. Furthermore, there were significant (r=0.869, P<0.01) positive correlations between the RC (relative changes) of spikelets per panicle and filled spikelets per panicle under the soil Cu treatment. 相似文献
388.
Zhang Z Bai M Bai M Bai X Pan Q 《Journal of the Air & Waste Management Association (1995)》2006,56(6):810-815
The removal of sulfur dioxide (SO2) from simulated flue gases streams (N2/O2/H2O/SO2) was experimentally investigated using microgap discharge. In the experiment, the thinner dielectric layers of aluminum oxide (Al2O3) were used to form the microgap discharge. With this physical method, a high concentration of hydroxyl (OH*) radicals were produced using the ionization of O2 and H2O to further the conversion of SO2 into sulfuric acid (H2SO4) at 120 degrees C in the absence of any catalysts and absorbents, which were captured with the electrostatic precipitator (ESP). As a result, the increase of discharge power and concentrations of O2 and H2O increased the production of OH. radicals resulting in enhanced removal of SO2 from gas streams. With the test and analysis, a number of H2SO4 droplets were produced in experiment. Therefore, a new method for removal of SO2 in semidry method without ammonia (NH3) additive was found. 相似文献
389.
Adverse health effects of outdoor air pollutants 总被引:3,自引:0,他引:3
Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution. A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented. Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO. Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005. The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1-7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public. 相似文献
390.