Fate of N-nitrosodimethylamine, trihalomethane and haloacetic acid precursors in tertiary treatment including biofiltration

The presence of disinfection by-products (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) and N-nitrosamines in water is of great concern due to their adverse effects on human health. In this work, the removal of N-nitrosodimethylamine (NDMA), total THM and five HAA precursors from secondary effluent by biological activated carbon (BAC) is investigated at full and pilot scale. In the pilot plant two filter media, sand and granular activated carbon, are tested. In addition, we evaluate the influence of ozonation prior to BAC filtration on its performance. Among the bulk of NDMA precursors, the fate of four pharmaceuticals containing a dimethylamino moiety in the chemical structure are individually investigated. Both NDMA formation potential and each of the studied pharmaceuticals are dramatically reduced by the BAC even in the absence of main ozonation prior to the filtration. The low removal of NDMA precursors at the sand filtration in comparison to the removal of NDMA precursors at the BAC suggests that adsorption may play an important role on the removal of NDMA precursors by BAC. Contrary, the precursors for THM and HAA formation are reduced in both sand filtration and BAC indicating that the precursors for the formation of these DBPs are to some extent biodegradable.     

钢筋混凝土极短柱抗剪承载力分析

极短柱的剪跨比往往超出了抗剪强度计算公式的适用范围 ,本文通过对以往试验结果的分析 ,以及对现有的几种计算公式的比较 ,综合出一个与试验值符合较好的计算公式 ,并就如何增加极短柱抗剪强度、提高极短柱延性作出了一些探讨     

浅谈厂房软基地面处理

采用碎石振动桩处理吹砂地面以及用土工布和塑料排水板加堆载预压是处理加固软基地面行之有效的方法。前者利用挤压原理将松散地面改造为密实度较高的地基。后者是利用砂井的原理，将水排出，让地基先压缩沉降。它们对提高软基的极限强度．增加地基的稳定性。减少地基沉降量有着显著的作用。     

宁波主要公园植物配置的特点与分析

通过对宁波14个主要公园现有植物种类、数量及面积的调查与分析,认为乔灌木比例宜在1:45-60之间;乔木数量不宜太多,每公顷宜在150-250株,以便给灌木提供充足的空间与光照条件;灌木应尽量增加种类的数量,减少色块的应用,同时应在总面积中保持2-3株/M2左右。常绿与落叶乔木比例宜在3:2,常绿与落叶灌木宜在5-6:1的比例。文章还针对不符合植物配置原理的产生原因进行分析并提出了相应的建议。     

压水板式后弯管波浪能发电装置的试验研究

提出了一种带有压水板的新颖后弯管波浪能发电装置,旨在提高后弯管波浪能发电装置的俘获宽度比,拓宽装置响应频宽。建立了压水板式装置物理模型,并在波浪水槽中开展物理模型试验,通过气压测量结合流量-气压关系式计算得到装置俘获转换的气动能量。研究了喷嘴比、锚泊点位置、吃水深度对装置性能的影响,并对比了一系列波浪要素条件下压水板式装置与常规型式装置的性能。发现在测试波周期范围内压水板式装置的最大俘获宽度比常规型式的大13.8%,俘获宽度比>70.0%的频响宽度比常规型式的宽21.9%,压水板实现了增效宽频作用。     

Development of a new loading test apparatus for microfocus X-ray CT and its application to the investigation of soil behavior surrounding driven open-section piles

In recent years, X-ray CT scanners with task-specific modifications, such as microfocus and/or a synchrotron, have been widely implemented in a variety of fields, including medical and industrial fields. Since microfocus X-ray CT systems enable the visualization of whole samples, and also yield a relatively high resolution of the region of interest in the sample, they are commonly utilized in the fields of soil mechanics and geotechnical engineering. This paper describes a novel loading test apparatus that is specifically designed for microfocus X-ray CT systems capable of performing loading tests to investigate soil behavior during the installation of driven open-section piles. The loading tests were designed to take the micro-level spatial resolution of microfocus X-ray CT systems into account. Digital image correlation (DIC) is subsequently implemented to analyze the obtained CT images, making it possible for measurements to be taken of the displacement fields in the ground following installation of the model pile. Finally, the versatility of this novel test apparatus is proof of its high potential for application in different types of loading tests.     

Investigation into performance of deep excavation in sand covered karst: A case report

Performing deep excavations in karst regions is likely lead to geo-hazards, e.g. sinkholes, water ingress, and ground surface settlement. This case report presents the performance of a 16-m deep excavation in sand covered karst in Metro Line no. 9, Guangzhou, China. The performances during deep excavation, including lateral wall deflection, vertical wall movement, ground surface settlement, and settlement of adjoining buildings, were monitored and evaluated. Based upon the interpretation of the field measurements, the following major findings were obtained: (i) the lateral wall deflection and surface settlement measurements were smaller those cited in other case studies with similar geological conditions, (ii) both the grouting of the karst cavern and the use of the socket diaphragm wall panel dominated the performance of the deep excavation; (iii) the type of the founding structure could significantly affect the settlement development of the adjoining buildings. This case report provides insight into the design and construction of deep, narrow excavations in sand covered karst in a metropolitan environment.     

Granulometry,cluster analysis and spatial distribution of manganese contaminated soils,Kgwakgwe, southeastern Botswana

The particle size distribution (PSD) of 400 Mn contaminated soil samples was established, and generated data were statistically analysed and spatially presented. The PSD for the 53 µm – 4 µm size fraction soil samples ranged from 11.05 to 100 wt %, whereas that for < 4 µm was from 0.3 to 30 wt %. Texturally, samples were dominantly silt loam, although silt and sandy loam were also present, as well as loam, loamy sand and clay classes. Six clusters were identified with cluster one being the most dominant occurring in sandy loam, silt loam and loamy sand. The < 53 µm fraction had three dominant areas, and the < 4 µm fraction had several unevenly presented populations as reflected in the maps. Because of its spatial distribution, the < 4 µm fraction may pose hazards to human health. Furthermore, predominance of Mn limits land use to subsistence agriculture with possibly low crop yield.     

试论城中村改造规划中控制性指标的确定-以西安市为例

西安市自启动城中村改造以来,一方面改善了城中村村民的居住生活环境,解决了安全隐患问题,另一方面为社会提供了大量商品住房,对西安加快城市化进程、完善城市功能、提升城市品质等方面起到了推动作用。随着城改工作逐步深入,改造工作中也出现了一些新的问题。本文对前期改造过程中关于规划控制性指标存在问题进行总结分析,并提出了关于城中村规划设计控制的几点建议。