Polychlorinated biphenyl Bulk

Volatilization. Transfer of chemicals across the air/water interface can result in either a net gain or loss of chemical, although in many cases the bulk concentration in the air above a contaminated water body is low enough to be neglected (20). When the atmosphere is the primary source of the contaminant, as for example polychlorinated biphenyls in some parts of the Laurentian Great Lakes, atmospheric concentrations obviously cannot be neglected. The Whitman two-film or two-resistance approach (21) has been applied to a number of environmental situations (20, 22, 23). Transport across the air/water interface is viewed as a two-stage process, in which both phases of the interface can offer resistance to transport of the chemical. The rate of transfer depends on turbulence in the water body and in the atmosphere, the... 

As shown in Illustrative Examples 19.3 and 19.4, often it is not immediately known whether an exchange process is controlled by transport across a boundary layer or by transport in the bulk phase. In Illustrative Example 19.3 we look at the case of resuspension of particles from the polluted sediments of Boston Harbor. We are interested in the question of what fraction of the pollutants sorbed to the particles (such as polychlorinated biphenyls) can diffuse into the open water column while the particles are resuspended due to turbulence produced by tidal currents in the bay. To answer this question we need to assess the possible role of the boundary layer around the particles. 

Polychlorinated biphenyls (PCBs) were first synthesized in 1864, and commercial use has been active since 1929. Over 1 million tons of PCBs have been produced commercially with different trade names, such as Aroclor, Clophen, Fenchlor, and Kanechlor. There are 209 PCB isomers or types, which differ from each other in the number and relative position of the chlorine atoms on the biphenyl molecular frame. A small number of these isomers are particularly toxic and are believed to account for the bulk of PCB-induced toxicity in animals. PCBs... 

If the density of the bulk product is greater than that of water, the product will continue to migrate downward through the water table aquifer under the continued influence of gravity. Downward migration ceases when the product is converted to residual saturation or when an impermeable surface is encountered. Polychlorinated biphenyls and other chlorinated organic solvents are usually denser than water and are characterized as DNAPLs. 

GeoMelt claims that its base technology has been granted a national Toxic Substances Control Act permit for the treatment of wastes containing up to 1.7 percent polychlorinated biphenyls (PCBs) (Campbell et al., 2005). Bulk vitrification was demonstrated for the treatment of waste from the Rocky Flats Environmental Technology site near Denver, Colorado.5 About 21,500 pounds of waste containing PCBs and low-level radioactivity were shipped from Rocky Flats to Waste Control Specialists near Andrews, Texas, and treated. 

The first fraction usually contains aUphatic hydrocarbons, polychlorinated biphenyls (PCB), and some monocychc aromatic hydrocarbons the bulk of aromatic hydrocarbons, l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and l,l-dichloro-2,2-bis(p-phenyl)-ethene (DDE) are found in the second fraction. Carbonyl compounds such as phenylal-... 

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