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排序方式: 共有1305条查询结果,搜索用时 31 毫秒
591.
采用了膜生物膜工艺处理含盐羧甲基纤维素生产废水。接种污泥为普通污泥,经驯化使其适应含盐废水,在污泥驯化阶段,生物膜表现出极佳的盐度冲击后恢复能力。通过较长的水力停留时间(5~15 d)和较低的COD有机负荷(平均1.6 kg/(m3·d)左右),生物膜COD去除率基本达90%。膜池内,悬浮固体浓度基本保持在5 000 mg/L以内;通过聚偏氟乙烯中空纤维膜过滤,出水悬浮固体浓度保持在5 mg/L以内。膜污染可通过重复的气水反洗和定期的化学清洗得以缓解。  相似文献   
592.
针对井喷爆炸事故造成的巨大经济和环境问题,从消除井场点火源出发,讨论了井喷发生后防止爆炸的问题。基于井喷爆炸事故统计信息,利用事故树法,分析了井场可能存在的点火源,在此基础上提出井场防止井喷爆炸的措施。分析发现井喷爆炸主要分布在井喷后小于5分钟和井喷后大于1小时时间段,点火源主要为井场存在的点火源和后续抢救工作时带入的点火源;井场点火源主要分为明火、电火花、撞击火花和静电火花,通过井喷爆炸事故统计分析,电火花和撞击火花同样应该引起重视。  相似文献   
593.
随着图形界面(GUI)在视屏作业中的大量使用,电脑用户已经很大程度上依赖于指向(Pointing)设备(比如鼠标)进行控制和操作。本项研究尝试研发电脑指向设备易用性测试方法,以更好的从工效学角度研究办公室视屏作业中的指向活动。指向设备易用性测试方法设计包括:标准化的指向测试;一系列能够准确描述指向的参数;用户满意度问卷。为了验证本测试方法,对具有代表性的笔记本电脑外接鼠标和内置触摸板进行了实验性的易用性测试。20名实验对象使用这两种设备完成了标准化的指向测试和满意度问卷。实验数据分析表明本指向设备易用性测试方法准确、有效。  相似文献   
594.
煤炭物流运输网络系统是由煤炭经停的节点企业和线路组成,任何一个环节出现问题都会对煤炭物流的顺利运行带来风险。本文对我国煤炭物流运输网络进行风险分析。建立风险评价的指标体系,采用模糊综合评价法进行风险评价。并根据评价结果,从完善煤炭物流网络节点企业职能及布局,加强煤炭运输通道建设等方面提出相应改进措施。分析了集装箱运输煤炭的优势。提出将射频识别技术应用于煤炭物流运输系统,并对其技术可行性和架构方案进行了探讨。对提高煤炭物流运输系统的运行效率,降低风险具有积极的意义。  相似文献   
595.
结合国际权威法规AsME最新要求,研讨承压设备焊缝超声检测使用相控阵(PA)技术的重要条件和方法要领,突出该技术的工程应用实际和装置选项须知。旨在为国内承压设备推广应用PA技术、制定相应行业标准和刷新、升级UT人员的操作技能,提供有用借鉴。  相似文献   
596.
This work investigated the degradation of humic acid (HA) in aqueous solution by electrochemical oxidation with Antimony- and Nickel-doped Tin oxide electrode (Ni-Sb-SnO2/Ti electrode) as the anode. Initial concentrations of HA ranged from 3 to 9 mg-L 1. Under such a concentration scope, the degradation of HA was a mass transfer controlled process. Degradation rate increased with the increase of HA initial concentration. Test on the effect of tert-butanol revealed that · OH played an important role in the oxidation of HA. The absence of cation Ca2+ was beneficial to HA degradation, which suggested that both indirect and direct electrolyze happened during the whole electrochemical oxidation process. Alkaly (pH = 12) and neutral (pH = 7) conditions were benefical to HA degradation.  相似文献   
597.
Precise and sensitive methods for the simultaneous determination of different classes of antibiotics, including sulphonamides, fluoroquinolones, macrolides, tetracyclines, and trimethoprim in surface water, sediments, and fish muscles were developed. In water samples, drugs were extracted with solid-phase extraction (SPE) by passing 1000 mL of water through hydrophilic lipophilic balanced (HLB) SPE cartridges. Sediment samples were solvent-extracted, followed by tandem SPE (strong anion exchange (SAX) + HLB) clean-ups. Fish muscles were extracted by a mixture of acetonitrile and citric buffer (80:20, v/v) solution, and cleaned by SPE. Liquid chromatography-tandem mass spectrometry (LC-MS/ MS) with multiple reaction monitoring (MRM) detection was employed to quantify all compounds. The recoveries for the antibiotics in the spiked water, sediment, and fish samples were 60.2%-95.8%, 48.1%-105.3%, and 59.8%- 103.4%, respectively. The methods were applied to samples taken from Dianchi Lake, China. It showed that concentrations of the detected antibiotics ranged from limits of quantification (LOQ) to 713.6 ng- L1 (ofloxacin) in surface water and from less than LOQ to 344.8 μg·kg-1 (sulphamethoxazole) in sediments. The number of detected antibiotics and the overall antibiotic concentrations were higher in the urban area than the rural area, indicating the probable role of livestock and human activities as important sources of antibiotic contamination. In fish muscles, the concentration of norfioxacin was the highest (up to 38.5 μg·kg-1), but tetracyclines and macrolides were relatively low. Results showed that the methods were rapid and sensitive, and capable of determining several classes of antibiotics from each of the water, sediment, and fish matrices in a single run.  相似文献   
598.
An innovative advanced wastewater treatment process combining biologic aerated filter (BAF) and sulfur/ ceramisite-based autotrophic denitrification (SCAD) for reliable removal of nitrogen was proposed in this paper. In SCAD reactor, ceramisite was used as filter and Ca (HCO3)2 was used for supplying alkalinity and carbon source. The BAF-SCAD was used to treat the secondary treatment effluent. The performance of this process was investigated, and the impact of temperature on nitrogen removal was studied. Results showed that the combined system was effective in nitrogen removal even at low temperatures (8℃). Removal of total nitrogen (TN), NH4+ -N, NO3-N reached above 90% at room temperature. Nitrification was affected by the temperature and nitrification at low temperature (8℃) was a limiting factor for TN removal. However, denitrification was not impacted by the temperature and the removal of NO3 -N maintained 98% during the experimental period. The reason of effective denitrification at low temperature might be the use of easily dissolved Ca(HCO3)2 and high-flux ceramisite, which solved the problem of low mass transfer efficiency at low temperatures. Besides, vast surface area of sulfur with diameter of 2-6 mm enhanced the rate of microbial utilization. The removal of nitrate companied with the production of SO42-, and the average concentration of SO27 was about 240mg.L^-1. These findings would be beneficial for the application of this process to nitrogen removal especially in the winter and cold regions.  相似文献   
599.
Combustion-generated hydrogen chloride (HCl) is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual-layer granular bed filter, at gas temperatures of 500℃-700℃ and n(Ca)/n(Cl)molar ratios of 1.0-5.0 using the silver nitrate titration method by dry adsorbent powders Ca(OH)2. Mainly, the adsorption efficiency of HCI and utilization efficiency of Calcium were studied, by varying relevant factors including n(Ca)/n(Cl), tempera- ture, feeding method, water vapor and CO2. With a relatively higher HCl concentration of 1000ppm, the experimental results revealed that 600℃ may be the optimum temperature for HCl adsorption when optimum n (Ca)/n(Cl) was 2.5 in our tests. The results also demonstrated that the feeding at a constant pressure was more effective, and the HCl adsorption efficiency could rapidly reach over 90% with n(Ca)/n(Cl) = 2.5 at 600℃. Furthermore, the HCl adsorption efficiency was found to be slightly promoted by water vapor, while could be impeded by CO2, and the utilization efficiency of calcium could be up to 74.4% without CO2, while was only 36.8% with CO2 when n(Ca)/n(Cl) was 2.5 at 600℃.  相似文献   
600.
High quality and low cost carbon can be prepared from Eupatorium adenophorum (E. adenophorum) and Buckwheat straw. The biosorbent was used for Cr(VI) removal. The effect of experimental parameters, such as pH, sorbent dosage and temperature were examined and the optimal experimental condition was determned. Solution pH is found influencing the adsorp- tion. Cr(VI) removal efficiency is found to be maximum (98%) at pH= 1. Langmuir and Freundlich adsorption isotherms were applicable to the adsorption process and their constants were evaluated. The adsorption data obtained agreed well with the Langmuir sorption isotherm model. The maximum adsorption capacities for Cr(VI) ranged from 46.23 to 55.19mg.g^-1 for temperature between 298 K and 308 K under the condition of pH = 1.0. Thermodynamic parameters such as free energy change (AG), enthalpy (AH) and entropy (AS) indicate a spontaneous, endothermic and increased randomness nature of Cr(VI) adsorption. Studies found that the raw E. adenophorum and buckwheat straw mixed materials with simple treatment had a high efficiency for the removal of Cr(VI) and would be a promising adsorbent.  相似文献   
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