Benzenes, chlorinated, effluents from

Coincident with the development of sampling procedures were the constant iterative improvements in extraction, separation, identification and quantitation of organic compounds. Special emphasis was placed on selected compound classes such as the polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorinated benzenes, and chlorinated dibenzo-p-dioxins (dioxins). The best available procedures were used to determine these components because they have known acute or chronic effects and previous studies suggested that they might be present in effluents from the combustion of coal alone and combination coal/RDF. 

Table IV. Chlorinated Benzenes in Stack Effluent From Coal-Fired Power Plants...

Another process, which is considered throughout this text, involves the separation of a miX ture consisting of HCl, benzene, and monochlorobenzene (MCB), the effluent from a reactoi to produce MCB by the chlorination of benzene. As discussed in Chapter 7, when separating a light gaseous species, such as HCl, from two heavier species, it is common to vaporize the... 

Materia] Balance of a Chlorination Process with Recycle A plant for the chlorination has the flowsheet shown. From pilot plant work, with a chlorine/benzene charge weight ratio of 0.82, the composition of the reactor effluent is... 

One of the major uses of activated carbon is in the recovery of solvents from industrial process effluents. Dry cleaning, paints, adhesives, polymer manufacturing, and printing are some examples. Since, as a result of the highly volatile character of many solvents, they cannot be emitted directly into the atmosphere. Typical solvents recovered by active carbon are acetone, benzene, ethanol, ethyl ether, pentane, methylene chloride, tetrahydrofuran, toluene, xylene, chlorinated hydrocarbons, and other aromatic compounds [78], Besides, automotive emissions make a large contribution to urban and global air pollution. Some VOCs and other air contaminants are emitted by automobiles through the exhaust system and also by the fuel system, and activated carbons are used to control these emissions [77,78],... 

Further chlorinated compounds detected in Lippe river sediments could not be attributed clearly to distinct emission sources. Within the group of chlorinated benzenes, tri-, tetra- and pentachlorinated isomers did not show siginicant distribution patterns. In contrast, samples from the upper areas (sampling locations 8 and 9) were significantly less contaminated by dichlorobenzenes. Among other applications dichlorobenzenes are ingredients of toilet cleaners. Therefore, their distribution pattern in Lippe river sediments may reflect partially the pollution from municipal effluents. 

For the chlorinated benzenes, a very similar distribution within the sediment core is observed as for some PAHs, e.g. benzo[a]pyrene. An elevated large-scale industrial activity related to these compounds can be deduced for the time between 1947 and 1955. We attribute the decrease in contamination towards the top layers to a reduction of emissions as a result of more efficient sewage treatment plants (Fig. 1A,B) as well as a modified array of products. The concentration profile of HCB (Fig. 6C) and all lower chlorinated benzenes (Tab. 2) suggests the dominance of industrial sources responsible for the contamination as contrasted to agricultural emission derived from pesticide usage. It should be noted that the contamination level of 1,4-dichlorobenzene was elevated in the time period between 1975 and 1980, comparable with concentration levels determined in Rhine river sediments 1982/83. The extensive use of 1,4-dichlorobenzene as an odorous ingredient of toilet cleaners contributed additionally to the contamination via sewage effluents (LWA, 1987/1989). 

Fuels that contain potentially harmful chemicals may produce effluents that contain hazardous materials. For example, fuels containing benzene could produce benzene in the exhaust under certain conditions. Since benzene is a hydrocarbon, it is generally easy to completely destroy if there is adequate oxygen, temperature, and mixing. Fuels containing chlorine or fluorine can produce dioxins and furans that are toxic. These are not as easy to eliminate from the exhaust, so some type of posttreatment system is often required to minimize these pollutants to acceptable levels. 

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