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为满足日益严格的排放标准,城镇污水处理厂污水深度处理势在必行.污水深度处理的难点和重点是脱氮和难降解COD的处理,结合国内污水深度处理工程实践介绍了几种常用的相关工艺.深度脱氮工艺包括反硝化深床滤池、MBR工艺、生物倍增工艺和多级AO类工艺;难降解COD深度处理工艺包括化学氧化工艺、活性炭(焦)吸附工艺和能够改善可生化性的预处理技术.总结了各工艺关键设计参数,可供参考借鉴. 相似文献
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难生物降解有机废水处理技术现状与发展 总被引:9,自引:1,他引:9
工业有机废水都含有毒性和稳定性强的污染物,对于这样的废水难以用常规的物理、化学及生物方法处理。对目前国内外难生物降解有机废水的主要处理技术进行了综述,包括生物处理、化学处理和物理处理及各种联合处理工艺,阐述了各种方法或工艺的优缺点及它们的研究现状及进展。得出了单一工艺对难生物降解有机物废水的处理都存在一定的局限性的结论,指出了新的联合工艺的开发与应用将成为难降解有机废水处理发展的方向。 相似文献
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介绍了我国阿维菌素废水处理技术研究现状,对目前的阿维菌素废水处理工艺进行了分类,按处理效果可分为初步净化工艺和深度净化工艺,对典型处理技术电解法、混凝法、上流式厌氧污泥床工艺、Fenton试剂氧化法及吸附氧化法原理进行了概要分析,提出由于阿维菌素废水处理工艺较多,且使废水基本能够达标排放,故应结合阿维菌素废水情况通过试验和经济技术论证来确定最佳的工艺和运行参数。 相似文献
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本文分析了涂装前预处理对涂装质量的影响,比较了二种预处理工艺的特点,建议采用新型的四合一工艺和二合一工艺,并以后者为优,它们可以克服传统四合一工艺的不足,明显提高产品质量。 相似文献
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过硼酸钠生产废水的处理成本非常高。选择经济合理的工艺、设备及回收利用废水中的有效组分,可降低废水处理费用和减少污染物排放。本文通过对三种典型的废水处理工艺、设备进行技术经济分析,最终得出最优的工艺、设备选择。 相似文献
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Na2SO4对硬石膏水化进程及其水化产物形貌的影响 总被引:1,自引:0,他引:1
通过硬石膏水化率、水化温度、液相离子浓度测定和硬化体显微结构分析,研究了Na2SO4对硬石膏水化进程和二水石膏晶体形貌的影响,从二水石膏晶体生长角度探讨了Na2SO4的作用机理.结果表明:Na2SO4可促进硬石膏溶解,使硬石膏水化率提高,水化热集中,水化潜伏期缩短,水化进程加快;Na2SO4还可提高二水石膏的析晶过饱和度,使二水石膏临界晶核半径减少,晶体成核与生长速率加快,晶体尺寸减小:Na2SO4形成富SO2-4液相,有利于二水石膏晶体结构基元形成,高SO2-4浓度改变了晶面在不同轴向生长的相对速率,使c轴方向的生长具有优势,从而改变了二水石膏晶体生长习性,使二水石膏晶体由板状变为针柱状. 相似文献
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Effect of physical and chemical characteristics on the washout resistance of calcium sulfate pellets
The washout resistance of bone substitute in body fluid is essential for its medical application. In the present study, the effect of physical and chemical characteristics of calcium sulfate pellets on the washout resistance is investigated. Special attention is paid to the effect of crystalline structure. A calcium sulfate hemihydrate powder was used as the starting material, then heated to a temperature up to 1225?°C. Using a synchrotron X-ray diffractometer, the phase evolution from hemihydrate to anhydrite is characterized. The washout resistance of hemihydrate is very poor under the attack of a large amount of simulated body fluid (SBF). The anhydrite can be categorized into III, II and I; the resistance of anhydrite III is also poor. Nevertheless, the anhydrite II shows an excellent resistance to washout. Furthermore, the preosteoblast MC3T3-E1 cells can attach and proliferate on the surface of anhydrite II pellet. The washout resistance of anhydrite I is poor for the formation of microcracks. 相似文献
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本文研究了在常压下钛石膏-H2SO4-H2O体系中石膏相向硬石膏相的转化,探索了反应时间、硫酸浓度和温度对石膏-硬石膏转化的影响。结果表明:提高反应温度、增大硫酸浓度和增加反应时间都有利于石膏向硬石膏转化;当石膏转化为硬石膏后,延长反应时间硬石膏不再发生转变;在温度为70 ℃和80 ℃时,体系中石膏与硬石膏共存,二者的微观形貌差异明显,石膏呈片状,硬石膏呈长方板状;当温度升温至90 ℃以上时,石膏完全转变为硬石膏,其微观形貌为长方板状;常压下,在50~100 ℃内,在钛石膏-H2SO4-H2O体系中发生的石膏-硬石膏的相变是石膏直接脱水形成硬石膏,没有中间产物形成。 相似文献
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Sebastian Seufert C. Hesse F. Goetz-Neunhoeffer J. Neubauer 《Cement and Concrete Research》2009,39(10):936-941
Technical OPC contains mixed sulfate carriers in varying amounts. Gypsum and anhydrite are added to the clinker during the milling process where the gypsum dehydrates partially to bassanite and anhydrite. Due to different hydration kinetics of these phases, it is crucial to be able to characterize the composition of sulfate in a cement system to reach an optimal and reproducible cement hydration. In the current paper different calcium sulfate compositions are investigated by XRD methods in order to identify phase content. Special focus is put on the discrimination of the hemihydrate (bassanite) and anhydrite III as well as on transformation processes of anhydrite III through ambient humidity. 相似文献
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G. Tzouvalas 《Cement and Concrete Research》2004,34(11):2113-2118
The hydration process of cement pastes is of great importance to the physicomechanical properties of the hardened material. Thus, substances that regulate the setting of cement, such as natural anhydrite, have attracted significant scientific interest during the past years. This paper briefly describes the results of utilization of natural anhydrite in cement pastes of CEM-I and CEM-II types. The aim of the study has been to inquire the extent of natural gypsum replacement by natural anhydrite. The result of the hydration process has been expressed by the setting time and the compressive strength development, with respect to the SO3−2 content of each mixture. The experimental data conclude that natural anhydrite can be a very efficient retarder of the setting of cement, with no significant change in the physicomechanical properties of the hardened pastes. 相似文献
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硬石膏生产硫酸和水泥的方法及发展前景 总被引:1,自引:1,他引:0
重点介绍硬石膏制硫酸联产水泥项目的关键技术要点,包括原料和煤炭成分混合均匀、配料精度和喂料量稳定、降低烧成热耗以提高SO2浓度、确定适当的配料率值及建立DCS控制系统。从产品的成本及收益的分析来看,硬石膏制硫酸联产水泥具有良好的社会效益和经济效益。 相似文献