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161.
采用三维电极电Fenton氧化法处理实际染料废水,探究了染料废水处理效果的影响因素。实验结果表明:以钌铱镀层钛电极为阳极、不锈钢板为阴极、粉末活性炭为颗粒电极,在粉末活性炭投加量为2.0 g/L、电流密度为0.5 mA/mm2、极板间距为3 cm、pH为2.0、硫酸亚铁投加量为0.50 g/L的最优工艺条件下,反应2 h后COD、TOC、氨氮、色度的去除率达到最大,分别为62.80%、41.15%、42.48%和95.00%;粉末活性炭作为颗粒电极可使染料废水COD去除率提高18个百分点;重复使用10次的处理效果与第2次基本持平。 相似文献
162.
在常温条件下,采用生物滴滤塔处理模拟甲硫醚废气,考察了气体空床停留时间(EBRT)、容积负荷、喷淋密度及营养液pH对生物滴滤塔性能的影响。实验结果表明:当EBRT为90 s、进气甲硫醚质量浓度为150 mg/m~3、喷淋密度为0.65 m~3/(m~2·h),营养液pH为6.8时,甲硫醚去除率为90%;容积负荷高于15 g/(m~3·h)时,对生物滴滤塔的性能产生抑制作用;EBRT为90 s及60 s时,最佳喷淋密度分别为0.56~0.65 m~3/(m~2·h)及0.65~0.75 m~3/(m~2·h);降解甲硫醚的微生物对pH的变化较敏感,最适营养液pH为6~7。 相似文献
163.
Method for Rapidly Assessing the Overtopping Risk of Bridges Due to Flooding over a Large Geographic Region 下载免费PDF全文
Yawen Shen Jonathan L. Goodall Steven B. Chase 《Journal of the American Water Resources Association》2017,53(6):1437-1452
Hydraulic events are a leading cause of bridge failures. While these hydraulic events are accounted for in bridge design, changing environmental and land use conditions require continual updating of this risk. For example, after a bridge has been constructed, streamflow can change in unanticipated ways as a result of land use changes, geomorphic changes, and climate change. The objective of this research was to create a screening method able to quickly and inexpensively estimate overtopping risk across a collection of bridges based on the current streamflow conditions. The method uses a geographic information system, nationally available and standardized datasets, and recent regression equations to quantify bridge vulnerability to overtopping for flooding with varying return periods. This screening method could also be used to assist decision makers in updating the Waterway Adequacy field in the National Bridge Inventory, which indicates the overtopping risk of bridges. The method was applied to a portion of the Hampton Roads region of Virginia, United States that includes 475 bridges. The results of the analysis, when combined with transportation data for bridges, aid decision makers to assign further resources to complete more detailed analyses of bridges identified as being at risk for overtopping. 相似文献
164.
Yuan-Na Xing Ying Guo Mei Xie Ru-Lang Shen 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1382-1387
A solid-phase microextration-based sampling method was employed to determine the concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE) and 1-chloro-2,2-bis(p-chlorophenyl)ethene (DDMU), in two estuarine bays, Daya Bay and Hailing Bay, of South China. Six DDT components including p,p′-DDT, o,p′-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, and p,p′-DDMU were detected in Hailing Bay, while only p,p′-DDD was found in Daya Bay. p,p′-DDD was the most abundant DDT component in both bays, sharply different from the previous finding in the water column of the Palos Verdes Shelf, California, USA that p,p′-DDE was prevalent. In addition, the occurrence of p,p′-DDMU (with a range of 0.047-0.21 ng/L in Hailing Bay) has not been reported around the globe, and its presence in our study region appeared to stem from dehydrochlorination of p,p′-DDD, favored under aerobic conditions, but further investigations are clearly needed to confirm the mechanism for generation of DDMU in estuarine environments. 相似文献
165.
Yu Ren Aijun Ding Tao Wang Xinhua Shen Jia Guo Jiamin Zhang Yan Wang Pengju Xu Xinfeng Wang Jian Gao Jeffrey L. Collett 《Atmospheric environment (Oxford, England : 1994)》2009,43(9):1702-1711
Measurement of ambient gas-phase total peroxides was performed at the summit of Mount Tai (Mt. Tai, 1534 m above sea level) in central-eastern China during March 22–April 24 and June 16–July 20, 2007. The hourly averaged concentration of peroxides was 0.17 ppbv (± 0.16 ppbv, maximum: 1.28 ppbv) and 0.55 ppbv (± 0.67 ppbv, maximum: 3.55 ppbv) in the spring and summer campaigns, respectively. The average concentration of peroxides at Mt. Tai, which is in a heavily polluted region, was much lower than hydrogen peroxide measurements made at some rural mountain sites, suggesting that significant removal processes took place in this region. An examination of diurnal variation and a correlation analysis suggest that these removal processes could include chemical suppression of peroxide production due to the scavenging of peroxy and hydroxy radicals by high NOx, wet removal by clouds/fogs rich in dissolved sulfur dioxide which reacts quickly with peroxides, and photolysis. These sinks competed with photochemical sources of peroxides, resulting in different mean concentrations and diurnal pattern of peroxides in the spring and summer. A principal component analysis was conducted to quantify the major processes that influenced the variation of peroxide concentrations. This analysis shows that in the spring photochemical production was an important source of peroxides, and the major sink was scavenging during upslope transport of polluted and humid air from the lower part of the planetary boundary layer (PBL) and wet removal by synoptic scale clouds. During the summer, highly polluted PBL air (with high NOx) was often associated with very low peroxides due to the chemical suppression of HO2 by high NOx and wet-removal by clouds/fogs in this sulfur-rich atmosphere, especially during the daytime. Higher concentrations of peroxides, which often appeared at mid-nighttime, were mainly associated with subsidence of air masses containing relatively lower concentrations of NOy. 相似文献
166.
Ionic composition of TSP and PM2.5 during dust storms and air pollution episodes at Xi'an,China 总被引:1,自引:0,他引:1
Zhenxing Shen Junji Cao Richard Arimoto Zhiwei Han Renjian Zhang Yuemei Han Suixin Liu Tomoaki Okuda Shunsuke Nakao Shigeru Tanaka 《Atmospheric environment (Oxford, England : 1994)》2009,43(18):2911-2918
TSP and PM2.5 samples were collected at Xi'an, China during dust storms (DSs) and several types of pollution events, including haze, biomass burning, and firework displays. Aerosol mass concentrations were up to 2 times higher during the particulate matter (PM) events than on normal days (NDs), and all types of PM led to decreased visibility. Water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, F?, Cl?, NO3?, and SO42?). were major aerosol components during the pollution episodes, but their concentrations were lower during DSs. NH4+, K+, F?, Cl?, NO3?, and SO42? were more abundant in PM2.5 than TSP but the opposite was true for Mg2+ and Ca2+. PM collected on hazy days was enriched with secondary species (NH4+, NO3?, and SO42) while PM from straw combustion showed high K+ and Cl?. Firework displays caused increases in K+ and also enrichments of NO3? relative to SO42?. During DSs, the concentrations of secondary aerosol components were low, but Ca2+ was abundant. Ion balance calculations indicate that PM from haze and straw combustion was acidic while the DSs samples were alkaline and the fireworks' PM was close to neutral. Ion ratios (SO42?/K+, NO3?/SO42?, and Cl?/K+) proved effective as indicators for different pollution episodes. 相似文献
167.
C/N比和曝气量影响MBR同步硝化反硝化的研究 总被引:9,自引:3,他引:6
通过连续运行MBR研究了C/N比和曝气量对同步硝化反硝化的影响,结果表明,在环境温度13~23℃,MLSS为6.0~6.8 g/L,进水NH+4-N浓度50 mg/L,曝气量0.5 m3/h,HRT为6 h实验条件下,总氮去除率随着进水C/N比的增加而增加,在C/N比为6∶1~8∶1时,TN去除率达到79%~89%,低的C/N比抑制反硝化,过高的C/N比增加了碳源补加的成本。改变反应曝气量,当C/N比为6∶1,曝气量为0.4 m3/h时,TN的去除率达到了最大值85%。曝气量过高或过低,TN去除率均下降。并对在不同曝气量下MBR 内的DO 值分布进行了初步研究。 相似文献
168.
硝酸盐对反硝化除磷过程的影响分析 总被引:4,自引:1,他引:3
在厌氧/缺氧间歇反应器内考察了硝酸盐进水浓度及进水方式对反硝化除磷过程的影响。结果表明:在缺氧阶段,反硝化除磷菌(DPBs)可将硝酸盐转化为亚硝酸盐,当硝酸盐浓度较低时,DPBs以亚硝酸盐为电子受体吸磷。进水COD浓度为220 mg/L,正磷浓度为6.8 mg/L,硝酸盐初始浓度为26 mg/L时,系统达到最佳脱氮除磷效果,期间亚硝酸盐浓度积累至10.71 mg/L。采用连续流投加硝酸盐的方式更利于氮磷的高效去除。 相似文献
169.
哈尔滨市城市内涝监测预警系统建设 总被引:2,自引:0,他引:2
简要介绍了哈尔滨市城市内涝监测预警系统的主要组成部分、核心技术及理论基础、重要应用价值及意义,并通过在一次强降水实例中的检验,证明该系统具有较高的精确度.在系统核心环节--积水仿真模型的建立中,该项目突破了传统规则网格的划分法,而是根据城市地形地貌特点独创了无结构不规则网格技术.此外,仿真模型中对排水工程设施进行了数字概化,首次实现了地面积水与管道水体模拟之间的结合;初步解决了哈尔滨特有的陆地泵排水模拟问题;将监测雨量信息和数值天气预报信息带入仿真模型,实现了气象学与水文学的结合.通过运行该系统,可以提高对积水预报的准确度. 相似文献
170.
注浆法治理公路黄土暗穴病害的试验研究 总被引:1,自引:1,他引:0
注浆法是公路工程中治理暗穴的一种新方法.针对湿陷性黄土地区公路工程中大量发育的暗穴病害,通过室内浆液材料物理力学性能试验与工程现场模拟注浆效果试验,分析了以水泥为主剂的注浆材料在不同配合比情况下治理公路工程中暗穴的效果.室内外试验结果分析表明:浆液水灰比在2.5∶1~1.5∶1之间较为适宜;在不影响路基路面的正常压力下有效的加固半径是1.0 m~1.5 m;在特殊情况下为了使浆液快速凝结可以加入一定量的水玻璃作为速凝剂;可以采用二次注浆加强治理的效果. 相似文献