GAC adsorption filters as barriers for viruses, bacteria and protozoan (oo)cysts in water treatment

Granular Activated Carbon (GAC) adsorption filtration is commonly used in drinking water treatment to remove NOM and micro-pollutants and on base of the process conditions a certain capacity to eliminate pathogenic micro-organisms was expected. The experiences with the mandatory quantitative microbial risk assessment of Dutch drinking water revealed a lack of knowledge on the elimination capacity of this process for pathogens. The objective of the current study was to determine the capacity of GAC filtration to remove MS2, Escherichia coli and spores of Clostridium bifermentans as process indicators for pathogens and more directly of (oo)cysts of Cryptosporidium parvum and Giardia lamblia. Challenge tests with fresh and loaded GAC were performed in pilot plant GAC filters supplied with pre-treated surface water at a contact time which was half of the contact time of the full-scale GAC filters. MS2 phages were not removed and the removal of E. coli and the anaerobic spores was limited ranging from ≤0.1-1.1 log. The (oo)cysts of C. parvum and G. lamblia, however, were removed significantly (1.3-2.7 log). On base of the results of the experiments and the filtration conditions the removal of the indicator bacteria and (oo)cysts was largely attributed to attachment. The model of the Colloid Filtration Theory was used to describe the removal of the dosed biocolloids in the GAC filters, but the results demonstrated that there is a lack of quantitative knowledge about the influence of collector characteristics on the two major CFT parameters, the single collector and the sticking efficiency.     

Dynamic experimental simulation of hydrogen oriented underground gasification of lignite

The main goal of the study presented in the paper was to experimentally demonstrate the feasibility of lignite gasification to hydrogen-rich gas under the underground conditions simulated in the ex situ reactor. The in situ gasification conditions were simulated both in respect to the coal seam and the surrounding stratum. In the 54-h experiment the process of lignite gasification with oxygen and steam as gasifying medium was tested. The experiment was initially divided into three stages: the ignition stage, the oxygen stage and the steam stage.The gas produced in the steam gasification stage was characterized by the calorific value of 7.8 MJ/m³ and average hydrogen content of 46.3 vol.%. Unfortunately a rapid decrease in the temperature levels and in the amount of produced gas proved that the tested lignite of 53 vol.% moisture content was not suitable for steam gasification. A great amount of thermal energy was consumed for water evaporation which led to a considerable heat loss. An addition of stoichiometric amount of water in the system by adding steam caused the seam to extinguish. Thus only oxygen could be used as the gasifying medium in the gasification of the tested lignite. The average calorific value of gas produced in the stable operation during oxygen gasification stage equaled 5.2 MJ/m³ with the average gas production rate of 16.0 m³/h and the average hydrogen content in the produced gas of 26.4 vol.%.     

Eutectic freeze crystallization from the ternary Na2CO3–NaHCO3–H2O system: A novel scraped wall crystallizer for the recovery of soda from an industrial aqueous stream

Eutectic freeze crystallization was tested in a scaled up version of a scraped cooled wall crystallizer on an industrial aqueous sodium carbonate–sodium bicarbonate waste stream containing traces of molybdenum. A heat transfer rate of 5 kW m⁻² was maintained in the crystallizer. Sodium carbonate decahydrate with molybdenum content below 1 ppm and pure ice were produced by continuous crystallization at −3.8 °C by operating within the metastable zone width of bicarbonate. At −4.0 °C bicarbonate started to co-crystallize. The bimodal size distribution of the mixture resulted in poor filtration and purity of the salt product.     

DMF萃取精馏法分离丁二烯的工艺流程模拟

利用ASPEN PLUS化工流程模拟软件,对DMF法丁二烯装置中的第一萃取精馏塔进行了模拟,与实际生产装置的工艺参数对比表明:模拟计算的结果是准确的。根据模拟计算的结果,分析了溶剂烃比、回流比、溶剂进塔温度等工艺参数对分离过程的影响,并提出了优化的工艺条件。     

含硫和高硫原油的加工技术

介绍了俄罗斯原油、委内瑞拉原油的一般性质及目前国内首套加工俄罗斯原油的5.5 Mt/a常减压装置的主要工艺路线和新技术特点,并针对俄罗斯原油的性质和该常减压装置的设计特点、运行中存在的问题和采取的对策及建议进行了分析讨论,如装置对加工俄罗斯原油的适应性问题、以及轻烃回收问题等,同时也对3.5 Mt/a常减压装置掺炼委内瑞拉高硫原油以及第二次加工装置的运行情况加以分析,为国内大量加工俄罗斯原油及委内瑞拉原油装置的设计提供了良好的借鉴经验。     

如何降低铝电解过程中的电能损耗

现今,国内外铝厂生产使用的方法为冰晶石—氧化铝电解法,电能消耗便成为成本的一个主要部分,降低电能损耗则可较大幅度的降低成本,提高企业效益。根据影响电能损耗的主要原因：电流效率和平均电压,通过改变电流效率和平均电压,进而来降低电能损耗,降低成本。本文主要是介绍理论电能损耗和实际电流损耗的计算,降低实际电能损耗的实际意义,以及如何降低实际电能损耗。     

SMT车间管理与质量控制技术（续完）

针对新产品的导入过程、车间现场管理及质量控制技术进行了全面的阐述。尤其是对新产品导入过程中的SMT生产线配置原则、设备选择、车间基础设施要求及生产现场管理和质量控制技术等几个主要方面重点分析。为了更好地提高产品质量和生产效率,使企业赢得较高的经济效益,从人员技术培训、设备与工具管理、材料技术采购、工艺设计与流程控制等因素出发阐述了SMT车间管理与质量控制技术,使产品生产系统步入良性循环。     

氮气保护对无铅焊接工艺温度窗口的影响

无铅化电子组装中无铅焊料的高熔点、低润湿性给实际生产带来了很大挑战。为了改善润湿性,可适当提高焊接温度,但由于PCB及元件的工艺温度限制,导致了焊接工艺温度窗口变窄。氮气保护可以改善无铅焊料润湿性、防止氧化、提高焊接品质,更重要的是可以降低焊接峰值温度,扩大焊接工艺温度窗口。