Management of Fluid Mud in Estuaries, Bays, and Lakes. I: Present State of Understanding on Character and Behavior

Fluid mud is a high concentration aqueous suspension of fine-grained sediment in which settling is substantially hindered. It constitutes a significant management problem in rivers, lakes, estuaries, and shelves by impeding navigation, reducing water quality and damaging equipment. Fluid mud accumulations have been observed in numerous locations worldwide, including Savannah Harbor, U.S., the Severn Estuary, U.K., and the Amazon River Delta, Brazil. This paper describes the present state of knowledge on fluid mud characteristics, processes, and modeling. Fluid mud consists of water, clay-sized particles, and organic material and displays a variety of rheological behaviors ranging from elastic to pseudo-plastic. It forms by three principle mechanisms: (1) the rate of sediment aggregation and settling into the near-bottom layer exceeds the dewatering rate of the suspension; (2) soft sediment beds fluidized by wave agitation; and (3) convergence of horizontally advected suspensions. Once formed, fluid mud is transported vertically by entrainment and horizontally by shear flows, gravity, and streaming. If not resuspended, it slowly consolidates to form bed material. Quantitative relationships have been formulated for key fluid mud formation and movement mechanisms, but they rely on empirical coefficients that are often site- or situation-specific and are not generally transferable. Research to define general relationships is needed.     

济钢工程项目设备采购稽核管理方法

济钢工程项目设备采购稽核管理按照PDCA动态管理控制模式,从稽核管理的成因分析、风险辨识、完善流程等8个管理环节,制定了相应的管理措施。对设备采购人员以及采购过程中的设备规划与选型、采购计划、供应商选择、采购过程以及合同收尾阶段进行全面监督检查。实践表明,这种稽核管理方式实现了设备采购的闭环动态管理和管理的可控性。     

Influence of Sediment Structure on Erosional Strength and Density of Kaolinite Sediment Beds

The role of sediment pore-water chemistry and the resulting particle structure in determining the erosional stability of settled cohesive sediment beds in rivers, lakes, and estuaries is examined. Kaolinite sediment is used as the surrogate sediment in this experimental investigation with the beds settled from concentrated suspensions. The bed stability with respect to erosion or resuspension is measured in a laboratory flume as a function of sediment pore-water chemistry. The chemical properties varied are sediment pH, ionic strength, and natural organic matter. The remolded bed sample is prepared from a sediment suspension having controlled chemical properties that is allowed to settle into the flume bed where its erosional strength and density are determined with depth in the sample. Different structures of settled beds are observed with changes in chemical parameters. Under low pH and low organic content conditions, the initial suspension before settling is flocculated. The resulting settled beds show strong stratification with respect to erosional strength but weak stratification of bulk density with depth. On the other hand, under high pH or high organic content conditions at low ionic strength, the initial suspension is dispersed. The resulting settled beds have lower erosional strength and weak stratification of erosional strength with depth but strong stratification of bulk density with depth. This research shows that the relationship between erosional strength and bulk density of a settled bed depends strongly on the structure of the sediment particle associations as determined by pore-water chemistry.     

Predicting the Performance of Activated Carbon-, Coke-, and Soil-Amended Thin Layer Sediment Caps

In situ capping manages contaminated sediment on-site without creating additional exposure pathways associated with dredging, e.g., sediment resuspension, and potential human exposure during transport, treatment, or disposal of dredged material. Contaminant mass is not immediately removed in sediment capping, which creates concerns over its long-term effectiveness. Groundwater seepage can also decrease the effectiveness of in situ capping. This study compares the effectiveness of commercially available sorbents that can be used to amend sand caps to improve their ability to prevent contaminant migration from the sediments into the bioactive zone. Amendments evaluated include coke, activated carbon, and organic-rich soil. The properties relevant to advective-dispersive transport through porous media (sorption, porosity, dispersivity, and bulk density) are measured for each material, and then used as inputs to a numerical model to predict the flux of 2,4,5-polychlorinated biphenyl (PCB) through a sand cap amended with a thin (1.25-cm) sorbent layer. Systems with and without groundwater seepage are considered. Isolation times provided by the sorbent layers increased with increasing sorption strength and capacity (activated carbon?coke ≈ soil?sand). The effective porosity, dispersivity, and bulk density of the sorbent layer had little effect on cap performance compared to sorption strength (Kf). In the absence of seepage, all sorbents could isolate PCBs in the underlying sediment for times greater than 100?years and would be effective for most cap applications. With groundwater seepage (Darcy velocity = 1?cm/day), activated carbon was the only sorbent that provided contaminant isolation times greater than 60?years. Long isolation times afforded by sorbent-amended caps allow time for inherently slow natural attenuation processes to further mitigate PCB flux.     

Development of Effluent Concentration Models for Sediment Scoured from Catchbasin Sumps

The ability of catchbasin sumps and hydrodynamic separators to remove sediment must be balanced with their ability to retain the previously captured material by preventing scour. The sediment scour process in these storm-water structures differs from the unidirectional scour and sediment transport process that occurs in pipes and channels. The hydrodynamics is affected by the particular characteristics of the hydraulic structure. The study of sediment scour in these devices requires incorporation of all the factors involved in the scour phenomenon and is best supported through computational fluid dynamic modeling (CFD) verified experimentally. Scour can be documented in the effluent as suspended sediment or total suspended solids concentration, a parameter of critical importance in storm-water quality management. This paper presents two simplified models for estimating effluent suspended sediment concentration attributable to scour of previously captured sediment. These models are based on results obtained from full-scale physical experimentation and calibrated and validated CFD modeling over a wide range of operating conditions where different particles sizes would be scoured. This paper also shows the effects of the armoring layer and of homogeneous and heterogeneous sediment sizes on the effluent concentration patterns.     

Probabilistic Approach to Estimation of Urban Storm-Water TMDLs: Regulated Catchment

The present work is concerned with the development of a set of tools for the incorporation of various control measures—best management practices into an analytical probabilistic modeling approach for urban storm-water total maximum daily load (TMDL) estimation. Control measures are divided into two major groups—upstream and downstream, each requiring application of separate modeling principles elaborated in this paper. Applying Monte Carlo simulation to the developed set of expressions allows modeling the “end-of-pipe” parameters of urban storm-water discharges (runoff volume, discharge rate, and pollutant load) on an event average basis, as well as the stream parameters downstream of a storm-water discharge outlet. Model application is illustrated for a catchment regulated with an extended detention dry pond. Representative model results are presented, and a range of potential model applications is discussed. The capability to model the behavior of an urban storm-water system with the application of various control measures is the key precondition for the design of an optimal configuration of a water-protective strategy.     

Field Evaluation of Bauxite Residue Neutralization by Carbon Dioxide, Vegetation, and Organic Amendments

The objective of this study was to investigate the mechanisms and extent of bauxite residue (red mud) neutralization at the residue surface in field impoundments as a result of long-term reaction with atmospheric CO2 and addition of amendments to promote vegetation. The results showed that carbonation from atmospheric carbon dioxide reduces the pH of red mud from 12.5 to about pH 9.3 at the surface of storage cells, with the depth of neutralization dependent on the age of the stored residue (up to 1.2 m in 35 years). The presence of vegetation further lowered residue pH to about pH 8.5, with the depth of neutralization dependent on depth of root penetration. Sewage and yard-waste amendments accelerated neutralization and the establishment of vegetation and further lowered the residue pH to about pH 6.7, likely due to organic acid leaching. For vegetated areas, the root density (g roots/g soil) was proportional to the extent of neutralization of residue, with root density higher in near-surface residue than in deeper residue.     

工程项目中的合同管理

以某公司为例,介绍了强化工程项目管理中合同管理的具体措施,包括：合同管理机制建设、抓好评审环节、监控履行过程、风险管理、变更管理以及建立合同管理信息系统等。事实证明．加强合同管理是提升项目管理水平的必经之路。     

青海省纳赤台金矿床成矿流体特征及成因探讨

纳赤台金矿床位于东昆仑造山带东段中部。矿体受地层和构造共同控制,一般产在断裂破碎带、构造裂隙及节理中。矿床成矿流体盐度为0.82%~13.29%,密度为0.61~0.97 g/cm3;流体包裹体均一温度为195.9~443.1℃;成矿压力80.01 MPa,成矿深度为8.03 km。研究表明,该区中—晚元古代万保沟群碳酸盐地层提供了主要的成矿物质,晚华力西—印支期受构造造山作用影响,岩浆携带成矿流体、成矿物质沿断裂上升侵位,萃取围岩中大量的成矿物质,迁移至断裂破碎带或节理等部位沉淀成矿。总体上,该矿床为受地层和构造共同控制的中低温热液脉型矿床,相当于造山型金矿床系列的中成矿床。     

Building Energy Management as Continuous Quality Control Process

This paper describes a macroanalytic approach to energy management in buildings. Conventionally, energy improvement measures are designed and deployed in buildings, expecting and typically achieving energy savings from changes to the building envelope or energy systems such as lighting system retrofits. However, additional savings opportunities can be identified by analyzing the interaction between building systems and the influence of building occupants. An energy accounting system can provide the required wealth of data and information and facilitate the analysis on which to design and refine further retrofit measures. The problem of energy management is cast in the framework of a classical feedback control loop: A “sensor” (energy accounting system) monitors the utility consumption of the building in question, compares it with predefined “setpoints” (energy consumption targets) and analyzes the deviations within a comprehensive reporting system (the “controller”). In response to the analysis, adequate measures including occupant motivation are defined by the controller and applied by the “actuator” to the “system,” embracing the building and its occupant under the prevailing weather conditions. The system output is the actual energy and utility consumption that is compared with the target values, and the loop is closed. The paper discusses an implementation of an energy management system that has been applied successfully to the measurement and verification of utility cost savings in an energy savings performance contract in Germany. Building occupant motivation—a category of energy retrofit measures that is often overlooked—is presented. A set of tabular and graphical data illustration and analysis techniques is presented along with recommendations for building occupant motivation measures and associated implementation guidelines.     

Assessment of Agricultural NonPoint Source Model for a Watershed in Tropical Environment

Very little work on the application of watershed modeling has been done in the tropical climatic conditions of Thailand to explore the nature of environmental problems arising from nonpoint source pollution due to agricultural activities, and to evaluate possible remedial measures and strategies. The present study attempts to verify the suitability of a nonpoint source pollution model, the Agricultural NonPoint Source model, for the Huai Nong Prong watershed in Southeastern Thailand. Extensive fieldwork was carried out to collect data and information needed for the model preparation and application. The study has revealed that simulated runoff volume, sediment, and nutrient yield from the watershed with mixed land use and relatively high slopes match favorably with observed data. For the ten rainfall events simulated, the coefficient of performance, a measure of model efficiency (equal to zero for a perfect match), was 0.09, 0.47, 0.09, and 0.03 for runoff volume, sediment yield, total nitrogen, and total phosphorus, respectively. The model, however, could not accurately simulate peak flow rates, suggesting the need for changes in the modeling approach or governing equations and relationships to calculate peak discharges in a tropical environment.     

Numerical Modeling of River Flow for Ecohydraulic Applications: Some Experiences with Velocity Characterization in Field and Simulated Data

Information regarding the spatial and temporal organization of river flow is required for many applications in river management, and is a fundamental requirement in ecohydraulics. As an alternative to detailed field surveys and to mesohabitat reconnaissance schemes, potential exists to deploy numerical flow simulation as an assessment and design tool. A key question is the extent to which complex hydrodynamic models are really practical in river management applications. This paper presents experiences using sediment simulation in intakes with multiblock, a three-dimensional modeling code, in conjunction with a statistical approach for classifying the spatiotemporal dynamics of flow behavior. Even in a simple configuration, the model is able to replicate well flow structures which associate with the mesohabitat concepts used in field reconnaissance techniques. The model also captures spatiotemporal dynamics in flow and depth behavior at these scales. However, because the model shows differential performance between flow stages and between differing channel (bed form) units, the smaller-scale and discharge-dependent dynamics of some zones within the channel may be less-well represented, and the implications of this for future research are noted.     

Evaluation of Laser In Situ Scattering Instrument for Measuring Concentration of Phytoplankton, Purple Sulfur Bacteria, and Suspended Inorganic Sediments in Lakes

A laser in situ scattering and transmissometry (Lisst-100) probe has been used for estimating the particle-size distribution of phytopankton, purple photosynthetic sulphur bacteria (Chromatiaceae), and suspended inorganic sediments in different lakes. Results from Lisst-100 have been compared to laboratory measurements, such as those obtained by using a Galai laser size analyzer (GL), an optical microscope (OM), and a flow cytometer (FC). Although all of these instruments were shown to provide reliable values of the particle number concentration for the given populations, the Lisst-100 was the fastest and most reliable instrument because it did not require manipulation of the samples—which is not the case of GL, OM and FC instruments—and avoided the tedious procedure of microscopic counts. The total particle volume concentration results obtained with Lisst-100 differed from those obtained with GL for populations with large and porous aggregates, such as phytoplankton cells. The difference was attributed to the breakage of fragile algal aggregates resulting from the measuring procedure used by GL. Although for suspended sediment particles both instruments gave the same results for the total particle volume concentration, the particle-size distribution obtained with GL was found always shifted to smaller diameters than with Lisst-100, probably because inorganic sediment particles present compact aggregates. When these aggregates break, they split into a high number of small particles that contribute the same to the total volume concentration as the previous aggregates. Finally, results of the total particle volume concentration with Lisst-100 were in accordance with those obtained with GL for the Chromatiaceae population, because cells remained in a dispersed phase. A good correlation was found between the total particle volume concentration of Chromatiaceae measured with Lisst-100 and the concentration of bacteriochlorophyll a (BChl a), which is the parameter habitually used to estimate the concentration of Chromatiaceae. Therefore, Lisst-100 was found to be a reliable instrument to estimate the Chromatiaceae concentration in aquatic ecosystems.     

转炉除尘污水污泥处理利用技术实践与探讨

通过对转炉除尘污水及污泥处理系统运行实践的分析，研究探讨了采取粗颗粒预分离、磁凝聚与药凝聚复合处理、保持水质稳定、污泥压榨过滤、泥浆泵送烧结以及加强操作管理等技术措施，以解决转炉污水污泥处理难题。     

Institutional arrangements for flood hazard management in Malaysia: an evaluation using the criteria approach

Institutional aspects of flood hazards significantly affect their outcomes in Malaysia. Institutional arrangements to deal with floods include: legislative activity, organisational structures, attitudes and sub-culture, and policies and instruments. When assessed in terms of four specific criteria, institutional aspects of flood hazards are found to be largely inadequate. Disaster reduction programmes are over-dependent on a reactive approach based largely on technology and not even aimed at floods specifically. Structural flood reduction measures are the predominant management tool and, although the importance of non-structural measures is recognised, thus far they have been under-employed. Current laws and regulations with regard to flood management are also insufficient and both the financial and human resources of flood hazard organisations are generally found to be wanting. Finally, economic efficiency, equity and public accountability issues are not adequately addressed by institutional arrangements for flood hazards.     

Cognitive behavior modification and modeling for test anxiety.

11 male and 37 female test-anxious undergraduates were randomly assigned to 1 of 3 experimental or 2 control conditions: (a) a core treatment, which consisted of D. H. Meichenbaum's (1972) cognitive behavior modification and study skills training, (b) the core treatment plus videotaped modeling, (c) the core treatment plus rehearsal modeling, (d) study skills control, and (e) waiting list control. On self-report measures, treated groups improved more than controls, with the rehearsal modeling condition ranking first among the treatments. No treatment led to significant improvement in academic performance, a finding consistent with the majority of test anxiety studies which have used grades as a dependent variable. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

UTILIZATION OF ALUMINA RED MUD FOR SYNTHESIS OF INORGANIC POLYMERIC MATERIALS

Red mud is a residue coming from the metallurgical treatment of bauxite with the Bayer process. Million of tons of red mud are produced annually worldwide and disposed of on land, degrading vast areas. Therefore, red mud utilization is a first-priority issue for any alumina plant. In the present work, the potential use of red mud for synthesis of inorganic polymeric materials through geopolymerization process was studied. The main focus was the production of inorganic polymeric materials that could be used in the construction sector as artificial structural elements such as massive bricks. The geopolymerization process involves a chemical reaction between red mud and alkali metal silicate solution under highly alkaline conditions. The product of this reaction is an amorphous to semi-crystalline polymeric structure, which binds the individual particles of red mud transforming the initial granular material to a compact and strong one. The effect of main synthesis parameters—like solid-to-liquid ratio, caustic soda as well as soluble silica concentrations, and metakaolin addition—on the properties of red mud-based inorganic polymeric materials was investigated. The results showed that the produced materials have high compressive strength, very low water absorption, satisfactory apparent density, and excellent fire resistance. Therefore, this work proved that the red mud-based inorganic polymeric materials have promising properties and have the potential to be used as artificial structural elements in the construction sector.     

Development of Tensile Hoop Stress during Horizontal Directional Drilling through Sand

Although horizontal directional drilling has become commonplace, there are problems associated with high drilling mud pressures causing hydraulic fracture leakage of mud out into the environment. Initiation of tensile fracture is examined here, using finite- element analysis to represent the sand material and the annulus of filtercake that forms around the borehole. The analyses examine the soil response as mud pressures are increased, including shear failure in the sand material and the cohesive filtercake layer. The study identifies the initial geostatic stress conditions and the drilling fluid pressures that initiate tensile stresses in the filtercake. The effects of filtercake thickness, borehole depth, and the location of the maximum tensile stresses are studied. Significant discrepancies are found relative to limits currently used in the industry. Tensile fracture may be responsible for some mud loss, but simple use of drilling mud pressures that prevent tensile circumferential stress may be overly conservative.     

Aggradation at Bridges

Aggradation at bridges causes the bridge waterway opening to be reduced, possibly resulting in upstream flooding and increased contraction scour. Aggradation results when the sediment load supplied to a reach of river from upstream exceeds its capacity to transport sediment. Solutions to aggradational problems at bridges are often complex and expensive. Solutions include increasing sediment transport through the bridge by modifying the channel, constructing an upstream sediment trap, redesigning the bridge, dredging, and treating the cause of the aggradation. At many bridges, aggradation problems can be severe. As an example, aggradation at a bridge in northern Pennsylvania is described. The benefits, disadvantages, and costs for various possible solutions to the example problem are compared and the most cost-effective solution is presented.     

Integrated Storm-Water Management for Watershed Sustainability

One aspect of integrated watershed management evaluates the impact of development on the local hydrologic cycle and, in particular, drinking water, wastewater, and storm-water infrastructure. Sustainable storm-water management focuses on selecting storm-water controls based on an understanding of the problems in local receiving waters that result from runoff discharges. For example, long-term problems associated with accumulations of pollutants in water bodies include sedimentation in conveyance systems and receiving waters, nuisance algal growths, inedible fish, undrinkable water, and shifts to less sensitive aquatic organisms. Short-term problems associated with high pollutant concentrations or frequent high flows (event-related) include swimming beach closures, water quality violations, property damage from increased flooding, and habitat destruction. A wide variety of individual storm-water controls usually must be combined to form a comprehensive wet weather management strategy. Unfortunately, combinations of controls are difficult to analyze. This will require new modeling techniques that can effectively evaluate a wide variety of control practices and land uses, while at the same time ensure that the flood-control objectives also are met. The results of these new models and novel techniques used for storm-water control then can be incorporated into an evaluation of the urban water cycle for a specific service area to determine whether storm-water controls can provide additional benefits such as reduction of potable water use and reduction of sanitary sewer overflow events.