Water contaminant transport

Catalyst fines, metals, rust, sand, and other material can be contained in residual fuel. These compounds arise from the crude oil, processing catalysts, water contamination, transportation, and storage of the fuel. If the total ash content is >0.20 wt%, deposits can form in burner systems and corrosion in high-temperature burners can occur. 

Bedient PB, Rifai HS, Newell CJ (1999) Ground water contamination transport and remediation, 2nd edn. Prentice-Hall, Upper Saddle River, NJ... 

Bedient, P. B., Rifai, H. S., and Newell, C. J. (1999). Ground Water Contamination, Transport and Remediation, Prentice Hall PTR, Upper Saddle River, NJ. 

The approach is very commonly used in transport models because mathematically it is relatively easy to incorporate. Goyette and Lewis [28] highlighted the utihty of values in screening level ground water contaminant transport models of inorganic ions with the caution that experimental conditions such as pH, electrolyte composition and soil type are similar to those being modeled. Viotti et al. [29] used values to model phenol transport in an unsaturated soil. Schroeder and Aziz [30] used this approach to account for PCBs sorption into dredged materials. Buczko et al. [31] used the Freundlich approach to model chromium transport in unsaturated zone. 

Nonaqueous phase Hquids (NAPLs) present special problems for soil and ground water cleanup. Contaminant transport through ground water depends in part on the water solubiHty of the compound. Because NAPLs cling to subsurface particles and are slow to dissolve in ground water, they hinder cleanups and prolong cleanup times. Dense nonaqueous phase Hquids (DNAPLs) migrate downward in the aquifer and can coUect in pools or pockets of the substmcture. Examples of DNAPLs are the common solvents tetrachloroethylene (PCE) and trichloroethylene (TCE) which were used extensively at many faciHties before the extent of subsurface contamination problems was realized. 

Pump and treat technology is inherently slow because it depends on ground water for transport of the contaminant to the extraction well. This characteristic is particularly troublesome when the contaminant is only slightly water soluble, adheres to the soil, or collects ia pools within the aquifer. 

Boiler Deposits. Deposition is a principal problem in the operation of steam generating equipment. The accumulation of material on boiler surfaces can cause overheating and/or corrosion. Both of these conditions frequentiy result in unscheduled downtime. Common feed-water contaminants that can form boiler deposits include calcium, magnesium, iron, copper, aluminum, siUca, and (to a lesser extent) silt and oil. Most deposits can be classified as one of two types scale that crystallized directiy onto tube surfaces or sludge deposits that precipitated elsewhere and were transported to the metal surface by the flowing water. 

Falta, R.W., Pruess, K. and Chestnut, D.A., Modeling advective contaminant transport during soil vapor extraction, Ground Water, 31, 1011-1020, 1993. 

Specific research investigations into sediment/particulate transport, sediment/water/contaminant interactions, soil (unsaturated and saturated) contaminant fate and transport, and biological degradation processes were identified as priorities by the Exposure Assessment workshops. 

The effects of transport on economy, people and on the environment are manifold. They include the consequences of transport accidents and fatalities, nuisance and health effects caused by steady noise exposure, air emissions and the exhaust and resuspension of particles, climate impacts by the emission of greenhouse gases, soil and water contamination, and the deterioration of natural habitats. Moreover, the financial burden of infrastructure provision and the additional travel and production costs caused by congestion should be mentioned but these items are mainly borne by transport users themselves and thus are only partly imposed on society as a whole. Not all of these effects are equally relevant for all means of transport. While accidents constitute the major problem of car travel, the railways definitely face a noise problem and air transport contributes most to the emission of climate gases. 

Surface tension is responsible for capillary effects and spreading of the NAPL over the water table. At about 20°C, water has a surface tension of 73.05 dyn/cm, whereas CC14 has a surface tension of only 26.95 dyn/cm. Therefore, water will be held in an unsaturated porous media by surface tension to a much greater degree relative to carbon tetrachloride (i.e., the permeability of porous media will be different with respect to each liquid). The ramifications will be important for contaminant transport of mixed wastes. 

Corapcioglu, M. Y. and Baehr, A. L., 1985, Immiscible Contaminant Transport in Soils and Groundwater with an Emphasis on Gasoline Hydrocarbons System of Differential Equations vs. Single Cell Model Water Science and Technology, Vol. 17, No. 9, pp. 23-37. 

Vinten et al. (1983) demonstrated that the vertical retention of contaminated suspended particles in soils is controlled by the soil porosity and the pore size distribution. Figure 5.8 illustrates the fate of a colloidal suspension in contaminated water during transport through soil. Three distinct steps in which contaminant mass transfer may occur can be defined (1) contaminant adsorption on the porous matrix as the contaminant suspension passes through subsurface zones, (2) contaminant desorption from suspended solid phases, and (3) deposition of contaminated particles as the suspension passes through the soil. 

Before considering the processes and means to quantify contaminant transport from land surface to groundwater, we first consider water movement in this region clearly water movement plays a key role in contaminant migration. This book focuses on chemical transport from land surface to the water table, and as such, we do not dwell on flow through the saturated zone. Numerous books on groundwater and contaminant hydrology are readily available. 

In this chapter, we examine the various mechanisms that influence chemical redistribution in the subsurface and the means to quantify these mechanisms. The same basic principles can be applied to both saturated and partially saturated porous media in the latter case, the volumetric water content (and, if relevant, volatilization of NAPL constiments into the air phase) must be taken into account. Also, such treatments must assume that the partially saturated zone is subject to an equilibrium (steady-state) flow pattern otherwise, for example, under periods of heavy infiltration, the volumetric water content is both highly space and time dependent. When dealing with contaminant transport associated with unstable water infiltration processes, other quantification methods (e.g., using network... 

Overland Runoff The fraction of rainfall or irrigation water that flows over a land surface from higher to lower elevations, known as overland runoff, is an additional pathway for contaminant transport. Runoff occurs when the amount of rain or irrigation water is greater than the soil infiltration capacity. The formation of a crust on the soil surface is a major contributor to runoff formation in arid and semiarid zones, because it decreases the infiltration capacity. The soil crust is a thin layer (0-3 mm) with a high density, fine porosity, and low hydraulic conductivity compared to the underlying soil. This skin forms as a result of falling raindrops or sodification of soil clays. 

A wide range of transport models is available for predicting water contamination and flow under urban runoff. Models based on conventional methods for runoff generation and routing were reviewed critically by Eliott and Trowsdale (2007). These authors suggest that future models on urban runoff should include a broad range of contaminants and improve the representation of contaminant transport. 

Many factors affect the transport of contaminants in the subsurface, including the (spatially and temporally variable) hydraulic and physicochemical characteristics of the solid phase and the properties of water and the contaminants themselves. In this chapter, we focus on several specific, representative examples of reactive (nonconservative) contaminant transport. 

After reaching the subsurface, contaminants are partitioned among the solid, liquid, and gaseous phases. A fraction of the contaminated gaseous phase is transported into the atmosphere, while the remaining part may be adsorbed on the subsurface solid phase or dissolved into the subsurface water. Contaminants dissolved in the subsurface aqueous phase or retained on the subsurface solid phase are subjected, over the course of time, to chemical, biochemical, and surface-induced degradation, which also lead to formation of metabolites. 

Delivery of Persistent Organic Contaminants to Alpine Waters Atmospheric Transport and Deposition... 

EXAMPLE 6.13 Drinking water contamination by trichloroethylene (steady-state groundwater transport with lateral dispersion)... 

Conkic et al. 1990). Chernobyl radioactivity, in particular and entering the Mediterranean as a single pulse, was rapidly removed from surface waters and transported to 200 m in a few days, primarily in fecal pellets of grazing zooplankton (Fowler et al. 1987). Bioconcentration factors (BCF) of Cs in hshes from Lake Paijanne, Finland — a comparatively contaminated area — ranged between 1250 and 3800 the highest BCF values were measured in the predatory northern pike (Esox lucius) a full 3 years after the Chernobyl accident consumption of these hshes was prohibited (Korhonen 1990). 

Corapcioglu, M. Y., and S. Jiang, Colloid-facilitated groundwater contaminant transport , Water Resour. Res., 29, 2215-2226 (1993). 

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