A comparison of instrumental dewatering methods for the separation and concentration of suspended sediment for subsequent trace element analysis     

A. J. Horowitz  K. A. Elrick  R. C. Hooper 《水文研究》1989,3(2):163-184

A comparison involving both field and laboratory trials was performed to evaluate the utility of two continuous-flow centrifuges and a tangential-flow filtration system for dewatering suspended sediments for subsequent trace element analysis. Although recovery efficiencies for the various devices differ, the analytical results from the separated suspended sediments indicate that any of the tested units can be used effectively and precisely for dewatering. Further, the three devices appear to concentrate and dewater suspended sediments in such a manner as to be equivalent to that which could be obtained by in-line filtration. Only the tangential-flow filtration system appears capable of providing both a dewatered sediment sample and a potentially usable effluent, which can be analysed for dissolved trace elements. The continuous-flow centrifuges can process whole water at an influent feed rate of 41 per minute; however, when suspended sediment concentrations are low (<30mg^?1), when small volumes of whole water are to be processed (30 to 401), or when suspended sediment mean grain size is very fine (<10 μm), influent feed rates of 21 per minute may be more efficient. Tangential-flow filtration can be used to process samples at the rate of 11 per minute.  相似文献   

硝态氮在河床垂向渗滤系统中环境行为的模拟实验   总被引：2，自引：0，他引：2  

黄瑞华  吴耀国  李云峰  杨炳超 《地球科学与环境学报》2006,28(3):92-96

采用自行设计的室内土柱实验装置模拟硝态氮在河床中的垂向渗滤过程,以阶梯状加大浓度的硝酸钾溶液为淋滤液,研究了硝态氮在河床垂向渗滤系统中的环境行为,借以了解河床渗滤系统对硝态氮污染的净化机理。实验表明,硝态氮在河床渗滤过程中分别参与了异化还原作用及反硝化作用。在以上两种作用的影响下,河床渗滤系统对硝态氮的去除率高达100%。但是,异化还原作用却导致了地下水中氨氮浓度的上升,这是值得注意的不利因素。  相似文献   

Groutability of cement‐based grout with consideration of viscosity and filtration phenomenon     

Jong‐Sun Kim  In‐Mo Lee  Jae‐Hyuk Jang  Hangseok Choi 《国际地质力学数值与分析法杂志》2009,33(16):1771-1797

The groutability depends on the properties of the grout, its injection processes, and on the mechanical properties of the soil formation. During the process of pouring cement‐based grouting into a porous medium, a variation with time occurs in the viscosity of grout suspension. In addition, the particle filtration phenomenon will limit the expansion of the grouted zone because cement particles are progressively stagnant within the soil matrix. In this paper, a closed‐form solution was derived by implementing the mass balance equations and the generalized phenomenological filtration law, which can be used to evaluate the deposition of cement‐based grout in the soil matrix. The closed‐form solution relevant to a particular spherical flow was modified by a step‐wise numerical calculation, considering the variable viscosity caused by a chemical reaction, and the decrease in porosity resulting from grout particle deposition in the soil pores. A series of pilot‐scale chamber injection tests was performed to verify that the developed step‐wise numerical calculation is able to evaluate the injectable volume of grout and the deposition of grout particles. The results of the chamber injection tests concurred well with that of the step‐wise numerical calculation. Based on the filtration phenomenon, a viable approach for estimating the groutability of cement‐based grout in a porous medium was also suggested, which might facilitate a new insight in the design of the grouting process. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

最小二乘法对多周期函数的周期筛选优化   总被引：1，自引：1，他引：0  

王玲玲  韩少红  曾安敏 《测绘工程》2005,14(4):52-54

运用最小二乘法对多周期函数的周期进行筛选优化研究,对不同周期组引起的中误差精度做了分析与比对.  相似文献   

超滤分级研究腐殖酸的结构组成   总被引：12，自引：0，他引：12  

李丽  冉勇  傅家谟  盛国英  彭平安 《地球化学》2004,33(4):387-394

利用切面流超滤技术将Pahokee泥炭腐殖酸分为相对分子质量不同的8个级分,并综合应用元素分析和傅立叶变换红外光谱(FT-IR)、固体13C核磁共振(13C NMR)和裂解-气相色谱-质谱(Py-GC-MS)技术详细研究了分级前后腐殖酸分子的结构组成特征.研究表明,随相对分子质量的增加,腐殖酸分子中的元素碳、元素氢含量增加;而元素氧和含氧官能团含量减少;并且低相对分子质量级分中含有相对较多的木本植物来源的芳香结构,而高相对分子质量级分中含相对较多微生物和植物来源的聚脂肪结构.本研究结果不仅说明环境中的腐殖酸分子是由许多相对分子质量不同、结构性质各异的腐殖酸分子组成,而且这些腐殖酸分子可能与腐殖酸形成过程中各种来源的物质在不同阶段的腐殖化产物有关,表明了腐殖酸类地质大分子物质的非均一性和复杂性.  相似文献   

傍河取水辐射井技术应用研究          下载免费PDF全文

张治晖  赵华  王桂芬 《探矿工程》2010,37(2):44-46

辐射井是傍河取水的有效开发模式,以富屯溪滩地辐射井傍河取水工程为例进行了试验研究,阐述了辐射井傍河取水的设计方法、涌水量计算、施工技术、试验井水质等。  相似文献   

城市垃圾卫生填埋场粘性土衬垫的截污容量及其研究意义   总被引：9，自引：0，他引：9  

刘长礼  王秀艳 《地质论评》2000,46(1):79-85

圾卫生填埋法的关键技术之一是防渗垫层的铺,国内外对防治在垫层的要求是“防渗”,所设计的防渗垫层所用材料种类多、价格贵、铺设复杂、成本高。若把垫层铺设的指导思想改为“截污”,可充分利用对垃圾具有净化或隔能力的场地粘笥土地和低垫层铺设民本。“截污容量”是基于这种思想提出出来的、用一博征粘性土的截污能力的物理参量,其科学和实用意义、试验测试及计算方法将在本文得到探讨。  相似文献   

Micro-properties of coal aggregates: Implications on hyperbaric filtration performance for coal dewatering     

C. Selomulya  J.Y.H. Liao  G. Bickert  R. Amal   《International Journal of Mineral Processing》2006,80(2-4):189-197

The recovery of ultrafine coal can be enhanced significantly by flocculating the particles prior to dewatering. It is thus crucial to be able to quantify the effects of aggregated particles on the separation efficiency, of which they are still not fully understood. This study focused on the relationship between the micro-properties (size, structure, and strength) of flocculated coal particles and the characteristics of filter cakes obtained through hyperbaric filtration. Tools such as small angle light scattering and confocal scanning laser microscopy were used to determine the aggregate structure. The comparative bond strength of aggregates generated under different flocculation conditions was measured through a non-dimensional approach. The effects of these properties on specific cake resistance, saturation, and moisture content, as indicative of the filtration performance, were observed. It was found that flocs generated using a moderate amount of flocculant dosage (60–100 g of polymer/tonne of coal) for this ultrafine coal (97% < 35 μm) optimised the properties of dewatered filter cakes. Although cakes composed of larger and stronger aggregates with more flocculant were found to have higher porosity, the effects on specific cake resistance and cake saturation were detrimental, possibly due to the increasing proportion of intra-aggregate pores that were harder to dewater. The trend was less noticeable at low filtration pressures where most of the dewatering occurred within the larger capillaries of the inter-aggregate zones. In addition, the presence of polymer molecules was responsible in absorbing residual moisture that could not be removed through mechanical means. Through a series of tests using pre-formed filter cakes, the amount of moisture retained by the flocculant was quantified to be approximately 10.2 mg of water for every addition of 1 g of polymer/tonne of coal, calculated per 100 g of filter cake produced from hyperbaric filtration in this case.  相似文献   

多光谱遥感异常提取技术方法体系研究   总被引：3，自引：2，他引：3  

杨金中 《国土资源遥感》2007,18(4):43-46

详细介绍了多光谱遥感异常提取方法体系——“去干扰（或称掩模）-主成分分析-异常筛选”（De-interfered Anomalous Principal Component Anomaly Filtration，以下简称DPF技术）的内容及工作方法，指出了技术体系应用时需要注意的问题。该 技术体系包括数据预处理、干扰去除、异常提取、异常后处理、异常筛选与推荐等5部分。在天山—北山、昆仑及冈底斯成矿带的 应用证明，该方法体系成效显著。  相似文献   

Water filtration through reflective microtidal beaches and shallow sublittoral sands and its implications for an inshore ecosystem in Western Australia     

Anton McLachlan  Ian G. Eliot  Des J. Clarke 《Estuarine, Coastal and Shelf Science》1985,21(1):91-104

Volumes of seawater filtered through the intertidal zone were measured on three modally reflective microtidal beaches in Western Australia. The filtered volumes were large, 19 m³ m^?1 day^?1 and 73 m³ m^?1 day^?1 on two ‘clean’ beaches but only 0·4 m³ m^?1 per tidal cycle on a beach covered in kelp and seagrass wrack. The mean residence times of this water in the interstitial system and its percolation paths were both short, 1–7 h and 2–5 m respectively. Water input was greater across a beach cusp horn than across a cusp embayment. Most input occurred in the upper swash zone where the water table was less than 20 cm deep. Tidal variations in input volumes were evident even with tide ranges of only 20 cm. The inshore zone off these beaches filters on average 0·07 m³ m^?2 day^?1 at an average depth of 5·5 m under 0·4 m waves of 6·5 s duration. The importance of these procedures in the mineralization of organic materials and the regeneration of nutrients for an inshore ‘lagoon ecosystem’ is estimated and discused.  相似文献