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991.
以人工配制生活污水为进水,室温条件下采用重力流排水管道反应器,研究投加铁盐对模拟污水管道中H2S的控制及其可能机理。试验首先测定了控制反应器和铁盐投加反应器内液相S 2-浓度的历时和沿程变化以及H2S气体的沿程差异,在此基础上通过静态试验提出铁盐投加后污水管道系统的生化反应机理并据此进行了铁硫物料衡算。结果表明:在Fe 3+投加浓度为30 mg/L时,管道反应器出水S 2-浓度平均低于1 mg/L,各反应槽中H2S气体浓度平均未超过40 ppm,远低于控制反应器;此时,约有44%的铁转化为磷酸铁,且该浓度足以抑制硫酸盐还原菌的活性。 相似文献
992.
用溶胶凝胶法研究了Na2OB2O3SiO2KH560无机有机复合涂层胶凝过程,测定了溶胶的粘度,用DSC,TG,XRD,IR,SEM分析了凝胶的物相和结构,目测并在SEM下观察了这种胶凝材料涂覆在水泥砂浆表面后的表观性能,分析了影响这些性能的因素.在无机Na2OB2O3SiO2三组分系统中掺加有机改性剂KH560,无机相和有机相之间以化学键形式结合,形成无机有机互穿的杂化结构.经130°C低温处理即能制备出致密、不开裂,且具有良好物化特性的无机有机涂层材料.影响涂层性能的因素主要有KH560掺量、涂层液粘度、热处理制度(包括加热制度和冷却制度)等 相似文献
993.
以^13C核磁共振技术为主,红外光谱技术为辅,测定和分析了超临界CO2中合成的聚丙烯腈(简称CO2—PAN)的三单元组立构规整度,推测出其在三单元序列上符合Bernoulli理论统计模型。同时发现,用上述2种方法测定的结果一致性良好。 相似文献
994.
ABR处理高浓度硫酸盐有机废水的性能 总被引:4,自引:0,他引:4
以人工配制的高浓度硫酸盐有机废水作为原水,研究了厌氧折流板反应器(ABR)处理高浓度硫酸盐有机废水的性能。结果表明,在温度为(33.2±0.1)℃、HRT为20~24h以及进水COD、硫酸盐浓度分别为5000和300~1500mg/L的条件下,ABR处理高浓度硫酸盐有机废水的效果较好,对COD的去除率可达90%以上,SO4^2-的还原率稳定在96%。COD/SO4^2-值是影响SRB与MPB竞争关系的重要指标,对COD去除率和SO4^2-还原率都有很大的影响。启动方式对厌氧反应器处理含硫酸盐废水的性能有很大的影响,低硫酸盐负荷启动方式会使MPB取得初始相对优势,SO4^2-还原对厌氧处理过程影响较小。 相似文献
995.
996.
Incidence of adenoviruses in raw and treated water 总被引:6,自引:0,他引:6
Adenoviruses are of major public health importance and are associated with a variety of clinical manifestations, i.e. gastroenteritis, eye infections and respiratory infections. The importance of water in the epidemiology of adenoviruses and the potential health risks constituted by adenoviruses in water sources and supplies are widely recognised. This study was conducted to assess the incidence of human adenoviruses in raw and treated water systems. Various raw and treated water were routinely monitored for the presence of adenoviruses, over a 1-year period (July 2000-June 2001). The supplies were derived from acceptable quality surface water sources using treatment processes, which conform to international standards for the production of safe drinking water. Adenoviruses were detected by firstly amplifying the viruses in cell cultures and then amplifying the extracted nucleic acids of these viruses using molecular techniques (nested PCR). The results indicated human adenoviruses present in 13 (12.75%) of the raw and 9 (4.41%) of the treated water samples tested. The combination of cell culture and nested PCR has proved to be a quick and reliable method for the detection of adenoviruses in water environments. 相似文献
997.
The effective removal of soluble natural organic matter (NOM) during water treatment can significantly decrease the ClO(2) demand of processed water. This can be achieved through the oxidation and/or the removal of NOM. The purpose of the study was to examine the influence of ClO(2) oxidation and subsequent GAC filtration on the final ClO(2) demand of treated water. The study showed the ClO(2) demand to be strongly correlated with the abundance of high molecular fractions of NOM in treated water. As it was shown, this part of NOM was effectively removed during the GAC filtration. Moreover, the pre-treatment of water with ClO(2) considerably increased the total capacity of GAC filters for organic and inorganic (i.e. chlorites) oxidation by-products. Therefore, the oxidation of NOM molecules in conjunction with a very efficient GAC filtration can be successfully employed to control the abundance of high molecular NOM components, and thus the ClO(2) demand of finished water. 相似文献
998.
2-Methylisoborneol (MIB) and geosmin (GSM) are taste and odor compounds produced by cyanobacteria in surface waters. While the strong odors and musty flavors of MIB and GSM are generally associated with poor water quality, the removal of these semi-volatile compounds presents a significant challenge to drinking water providers. Likewise in aquaculture, accumulation of these compounds in fish meat leads to quality problems and reduces marketability. Conventional water treatments are ineffective at removing low concentration of odor compounds. We report herein ultrasonic irradiation at 640 kHz leads to rapid degradation of MIB and GSM. While radical processes generally dominate during ultrasonic-induced degradation, pyrolysis appears to be responsible for a significant fraction of the observed degradation. Several pyrolytic products from MIB and GSM have been identified and degradation pathways are elucidated. The degradation of MIB and GSM follows the first-order kinetics and the rate constants are 0.07 and 0.12 min(-1), respectively. These results suggest ultrasonic irradiation maybe applicable as an effective method for removal of taint compounds from potable water supplies and fish farms. 相似文献
999.
基于Web的重大工程项目管理信息系统应用研究 总被引:7,自引:0,他引:7
本文介绍了基于Web的重大工程项目管理信息系统的开发思路、主要功能及不足之处 ,与以往的项目管理系统相比 ,本系统突出了集成管理和系统设计的思想 相似文献
1000.
Appraising the methods accounting for 3D tunnelling effects in 2D plane strain FE analysis 总被引:3,自引:1,他引:3
M. Karakus 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2007,22(1):47-56
Numerical analysis is widely used method in geotechnical engineering when calculating and predicting soil and rock behaviour under different loading and excavation conditions. For instance, simulation of tunnelling using 2D or 3D finite element (FE) analyses can often calculate any deformations and stress redistributions due to tunnelling operations without constructing real trial tunnels. Modelling the excavation process in 2D plane strain analysis, however, requires an approach that can consider 3D tunnelling effect as a result of volume loss. In addition, modelling shotcrete or similar support measures, using either beam elements, solid continuum elements or other special elements are needed to be adopted. Therefore, convergence-confinement, stiffness reduction, disk calculation and hypothetical modulus of elasticity (HME) soft lining approaches have been employed in the numerical analysis. Moreover, compatibility of each method with beam and solid continuum element models in 2D FE analysis was investigated. Thus, eight plane strain, non-linear FE analyses of tunnel construction in London Clay were performed and the results are presented and discussed in this article. 相似文献