不同絮凝剂对黑臭底泥沉降及脱水性能的影响

为解决黑臭水体疏浚底泥沉降性能差、含水率高、后续运送与处理处置不便的问题,采用7种絮凝剂(FeCl₃·6H₂O、Fe₂(SO₄)₃·9H₂O等)对黑臭底泥进行预处理,通过测定污泥沉降比、含水率、污泥比阻、分形维数等,研究不同絮凝剂对黑臭底泥脱水性能和沉降性能的影响。结果表明：所选絮凝剂均存在最优投加剂量,在最优剂量下都能显著降低黑臭底泥的污泥沉降比和底泥含水率,提高底泥脱水性能。其中聚丙烯酰胺的最优投加剂量最小,投加量为0.1%(与底泥干重的质量比)时,黑臭底泥的污泥沉降比小于检测限,脱水率94%,污泥比阻从6.47×1012m/kg降到2.58×1012m/kg,絮凝体结构较为紧密,分形维数大于2.5,絮凝效果最优。因此,聚丙烯酰胺是理想的黑臭水体疏浚底泥的预处理药剂,有良好的应用前景。     

竺山湖底泥疏浚对内源磷释放控制作用研究

竺山湖底泥疏浚表层50cm模拟试验表明,疏浚与对照柱间隙水PO43- -P浓度分别为3.6～40.8和9.2～715.6 μg/L,沉积物-水界面PO4 3- -P通量分别为-234.5～26.7 μg/(m2·d)和-214.9～2 885.6 μg/(m2·d),疏浚间隙水PO4 3- -P浓度和沉积物-水界面PO4 3- -P通量与未疏浚相比下降明显,说明底泥疏浚对竺山湖内源磷释放具有极好的控制作用.     

强化悬浮液絮凝造粒脱水过程的试验研究

通过活性污泥等料浆的絮凝造粒过程的试验研究，得到了该过程最佳絮凝剂用量及操作条件，根据湿法造粒原理结合试验结果，设计了低速螺旋絮凝造粒脱水强化装置，同时还推得出该装置分离效率的关联式，为污泥脱水和细微工业料浆的固液分离找到了一个经济高效的处理方法。     

遵义锰矿石精矿絮凝脱水工业试验

较详细地介绍了遵义锰矿石精矿絮凝脱水的工业试验情况。工业试验表明：絮凝剂，斜板机以及自动压滤机的联合应用，可有效地改善锰精矿的浓缩脱水效果，使浓缩溢流浓度从２％￣５％降到１％以下，锰精矿产率提高５％￣６％；回收率提高６％￣７％；滤饼水分从１５％以上降为１４％以下。工业试验为选矿车间全面改造精矿浓缩脱水方案的选择提供了可靠的依据。     

胶结充填电渗脱水试验研究

本文对胶结充填电渗脱水的速度特性，以及电渗脱水形成的胶结充填体的强度特性进行了试验研究．结果表明，与自然脱水法相比，电渗脱水法能加快脱水速度，提高胶结充填试块的单轴抗压强度和杨氏模量，降低胶结充填试块的泊松比。     

带式压滤机在转炉泥浆脱水中的应用

本文介绍了带式压滤机的性能及其在污水处理系统中的应用试验，文中对试验结果作了分析。     

硫化铜矿酸性废水底泥再利用试验研究

硫化铜矿酸性废水处理后产生大量底泥(HDS),属于Ι类工业固体废物。通过底泥成分检测与分析,综合运用生物学、土壤学、肥科学、园艺学、环境生态学和水土保持工程学知识,采用植物修复技术、土壤修复技术、微生物修复技术对底泥进行修复增肥,研究得出相应的底泥修复增肥配方工艺和标准,实现底泥增肥修复,从而替代土壤作为植生基质再运用于矿山生态修复工程,既实现底泥废弃物减量化循环再利用,又替代土壤,避免取土造成的环境破坏,同时节约大量的复垦资金,在大型硫化铜矿中具有广泛的推广应用价值和社会价值。     

高大采空场嗣后一次胶结充填脱水试验

本文介绍的链脱水管，适用于阶段矿房法采空场或其它高大采空场嗣后一次胶结或水力非胶结充填脱水，经东乡铜矿实践证明，是一行之有效的方法。     

KCl-NaCl-MgCl2熔盐体系的脱水及吸水性能试验研究

研究了采用氩气保护干燥脱水法制备MgCl_2质量分数分别为5%、10%、20%的KCl-NaCl-MgCl_2熔盐体系,考察了脱水温度和脱水时间对熔盐体系中H_2O质量分数的影响,熔盐体系的吸水性能,熔盐体系黏度与脱水温度之间的关系。结果表明:熔盐体系中,H_2O和MgO质量分数都较低,脱水效果较好;氯化镁水解程度较低;熔盐吸水性随MgCl_2质量分数增加显著提高;熔盐体系黏度随脱水温度升高而逐渐降低,具有良好的高温流动性。     

撞击流强化矿浆脱水过程机理及试验研究

撞击流是一种较新颖的技术方法，其基本思想是两不同流体沿同轴相对运动，并在其交汇处相到撞击、渗透、振荡，这种独特的方式，显著地强化了传递过程。文中通过对撞击流强化矿浆换热过程机理的研究，建立了两流三级撞击脱水的数学模型，并通过对矿浆脱水的试验研究，深入地探索了撞击流脱水反应过程中物料特性、换热温度、撞击速度等参数之间相互关系，为撞击流干燥技术的理论研究和应用奠定了基础。     

Segregation of the PAH-Contaminated Fraction of Hydraulically Dredged Sediment

Semivolatile hydrophobic organic contaminants (SV-HOCs) in sediments are a growing problem. Previous research in our laboratory has demonstrated that cleanup of the entire sediment may not be necessary due to sequestration of the majority of SV-HOCs like polycyclic aromatic hydrocarbons (PAHs) into the low density fraction that we hypothesize is separable from the bulk sediment hydraulically. In our current study, PAH-contaminated sediments from the Indiana Harbor Canal were hydraulically dredged and impounded in a stilling basin by the U.S. Army Corp of Engineers to evaluate a hydraulic dredge and characterize water treatment needs. This project provided an opportunity to test our hypothesis that a segregation of SV-HOC contaminated sediments would occur via hydraulic settling processes in the stilling basin at field scale. Following decommission of the basin, sediment cores were collected along transects from the basin influent immediately after removal of the overlying water, sectioned and characterized for physical and chemical parameters. As hypothesized, sediments showed large decreases in bulk density with increasing distance from the basin inlet. PAH concentrations increased up to 40-fold (120–4,900?mg?kg?1) and were highly correlated with the fraction of low density material in the sediment. Our results provide evidence that hydraulic dredging can result in a separation of highly contaminated sediment with high amounts of low density material from bulk sediment. This outcome may be either fortuitous or detrimental depending on the ultimate means of disposal. If subsequent dewatering occurs (such as in a confined disposal facility), prediction of PAH volatilization flux needs to be based on the in situ surface concentration which can be very high due to slow settling low density particles. Conversely, if the goal is beneficial reuse, higher density sediment with relatively low PAH levels near the inlet may be readily collected.     

Sediment Resuspension and Hydrodynamics in Lake Okeechobee during the Late Summer

In this study, in order to better understand the mechanisms affecting sediment resuspension, extensive data sets were collected in September and October of 2002 including wind velocity, wave, current velocity, water temperature, total suspended solid, suspended sediment concentration, and total phosphorus. Analyses of these data indicate that waves are the dominant factors in sediment resuspension while wind-induced currents are the primary forces to transport suspended sediments. Surface and bottom currents frequently flow in opposite directions, forming a stratified water column. A time lag exists between currents near lake bottom and wind forcing at the surface. The diurnal thermal stratification occurs in the deep region of the lake. A time lag is also found between suspended sediment concentration and wind speed. The study provides valuable storm-event data and mechanism analyses, which can improve our understanding of the lake circulation, wave dynamics, and their impact on sediment resuspension and vertical mixing in Lake Okeechobee. The data resulting from this study will be used to validate the Lake Okeechobee Environment Model which is used to predict the impacts of different management scenarios on lake activities.     

Spatial Variation of Sediment Sulfate Reduction Rates in a Saline Lake

Devils Lake in North Dakota is a terminal, multibasin, saline lake with an overall surface area that is currently approximately 44,520?ha (110,000?acres). Lake elevation has increased by more than 7?m within 10?years, and vast areas of prairie and cropland have been flooded. The lake is rich in sulfate, and water column sulfate concentrations are relatively uniform within each of the five major basins, but increase from 3.1?mM (300?mg/L) in West Bay to 31?mM (3,000?mg/L) in East Devils Lake. Sediment cores were collected from three of the basins at different water depths, and used in laboratory studies to evaluate the spatial distribution of sulfate-reducing bacteria (SRB) activity in the lake sediments. The high sulfate concentrations within the experimental sediment cores suggest that the activity of SRB is limited by the availability of suitable electron donors rather than by the availability of sulfate and that SRB activity can be defined by a zero-order volumetric rate constant (K0). Experimentally determined K0 values ranged from 11?to?88?mmol SO42? m?3?day?1. The water depths from which sediment cores were collected in Devils Lake are related to the elapsed time since inundation by the rising lake level. It was found that time since inundation influences the observed K0 value. Mean K0 values for cores from an average depth of 4.8?m (submergence time of about 5?years), and 9.4?m (submergence time of about 28?years) were 62 and 17?mmol SO42? m?3?day?1, respectively. The significant difference (two-tailed t-test, p<0.05) suggests that SRB activities in the Devils Lake sediments change with submergence times. A uniform sulfate reduction rate applied to all Devils Lake sediments is therefore only a crude approximation of reality.     

Case Study: Modeling of Sediment Transport and Wind-Wave Impact in Lake Okeechobee

There are increasing demands for reliable engineering tools for sediment modeling and water resources management. The Lake Okeechobee environmental model (LOEM), which was calibrated and verified to simulate sediment resuspension and transport in Lake Okeechobee, Florida, is a dependable tool to meet those demands. The LOEM contains 2,126 horizontal grid cells and 5 vertical layers. The primary hydrodynamic and sediment transport driving forces are wind waves, surface wind stresses, and inflows/outflows. The LOEM was calibrated and verified, using two sets of observed data from May 16 to June 13, 1989 and January 17 to March 3, 2000, respectively. The model results indicate that sediment solids are resuspended primarily by wind–wave action and transported by lake circulation. The strong relationship between significant wave height and suspended sediment concentration in the lake indicates that sediment resuspension is primarily driven by wind-induced waves. To simulate this sediment resuspension, the processes of wind–wave- and current-induced bottom shear stresses on the lake bed were added to the LOEM. Once resuspended, the suspended sediment is transported to different areas of the lake by wind-induced currents. The importance of wind-wave, currents, and their interactions to sediment transport is included and discussed. By using the comprehensive data set for model calibration and verification, the LOEM model is proven to be a useful tool to water sources management in the lake.     

青山湖水体总悬浮物浓度的高光谱遥感反演

利用2009年11月9日城市湖泊青山湖实测的水体高光谱遥感数据和同步水质采样数据,在分析水体固有光学特性的基础上,采用单波段、两波段比值和一阶微分3种算法进行了湖泊水体总悬浮物浓度(TSS)遥感反演研究.结果表明,单波段、两波段比值和一阶微分模型相关系数均较好,688 nm处一阶微分线性回归模型相关系数R<'2>为0.932 8,RMSE为2.896 1 mg/L,为最佳的TSS实测光谱遥感反演模型,可以用于青山湖水体TSS浓度的反演.该研究可为水质指标大面积的卫星遥感反演研究提供基础.     

Analysis of Sediment Characteristics and Total Phosphorus Models for Shagawa Lake

Shagawa Lake, Minn., received direct discharges of municipal wastewater for nearly 80 years and attained annual average total phosphorus concentrations of 30–60 μg∕L. A tertiary wastewater-treatment facility was constructed in 1973 that removed 80% of the external total phosphorus loading to the lake. The subsequent recovery of the lake was less than expected because of internal loading of phosphorus associated with accumulated lake sediments. Therefore, it is necessary to consider the effects of sediment phosphorus release to predict accurately the dynamics of phosphorus in Shagawa Lake. Measurements of the sediment characteristics have been used to estimate mass transfer coefficients that describe the release of phosphorus from the sediments. Three alternative mass-balance models were developed to determine the significance of the water sediment interactions. Recent field measurements were used to gauge the performance of the models. It was found, even more than 20 years after the reduction of the external loading, that sediment feedback of phosphorus has a significant influence on the dynamics of total phosphorus in the lake. Continued monitoring and data analysis of the sediment are necessary to refine the models and to predict accurately the ultimate fate of the lake.     

东平湖表层沉积物的理化特性及分布特征研究

以东平湖表层沉积物为研究对象,研究了东平湖表层沉积物理化特性分布特征.结果表明,东平湖沉积物pH值为7.80-8.26,属于中性偏碱性水质,而电导率和阳离子交换量的变化与水质情况有密切联系.东平湖沉积物有机质平均含量为29 mg/g,湖泊表层沉积物以粉砂质为主,对沉积物中营养元素的吸附以及迁移的影响较大.湖泊TN和TP含量的平均值为938.12、806.5 mg/kg,TP平均舍量比TN低约17.8%,且两者不存在显著相关性,表明东平湖沉积物中的氮和磷具有非同源性.     

Retardation of Dredged Material Leachate in Foundation Soils

Contaminated dredged material is often placed in confined disposal facilities (CDFs) designed and managed to control environmental impacts of the disposed sediment. This note presents equations for use in a screening procedure to evaluate the impact of a CDF on groundwater. The hydrologic evaluation of leachate production and quality model was used to simulate leachate production and transport through the foundation considering a range of foundation soil characteristics and contaminant properties. The model results were used to develop predictive equations of contaminant attenuation and travel time in the foundation soils. When used with equations to predict dispersion in the aquifer, contaminant exposures at receptor locations can be predicted, which is essential in leachate screening applications. The approach does not consider degradation or permanent sequestration of contaminants. Therefore, the procedure is conservative in that it may overestimate actual leachate concentrations and underestimate actual travel times.     

Computerization in the OR

This article highlights the process of establishing a computerized scheduling and materials management system in a surgical department. The following facets of the computerization process are discussed: options staff members should consider when choosing a computer system, the importance of scheduling and inventory control, cost savings, how computer systems work when using electronic data interchange and bar coding, and case studies.