Incineration, polychlorinated

Wastes containing PAHs may be effectively destroyed by various incineration processes as mentioned briefly in the above section. Weber et al. (2001) have studied the mechanisms of formation of polychlorinated diben-zofurans (PCDF), polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN) and polychlorinated benzenes (PCBz) from the degradation of PAHs in two types of incinerators, the stoker type- and the fluidized bed incinerators. Their studies have revealed the occurrence of a sequence of steps, such as the cleavage of C-C bond in the PAHs, chlorination at these cleaved positions, further chlorination or oxygen insertion at the ortho positions to the chlorine atoms in the intermediate chlorinated species. A perylene structure in soot is proposed as the basis for the observed PCDF pattern in the fluidized bed incinerators. Polychlorinated dibenzo-dioxins (PCDD) and the polychlorinated... 

Dioxin and Furan Emissions. The emissions of polychlorinated dibenzo-/)-dioxins (PCDD) and polychlorinated dibenzo-furans (PCDF) from incinerators (4) are of interest to the pubHc, scientists, and engineers. The U.S. EPA classifies 2,3,7,8-tetrachlorodibenzo-/)-dioxin (2,3,7,8-TCDD) as the most potent carcinogenic compound it has evaluated. It is also Hsted as the agency s most potent reproductive toxin (4). 

SW-846, is used to measure emissions of semivolatile principal organic constituents. Method 0010 is designed to determine destruction and removal efficiency (DRE) of POHCs from incineration systems. The method involves a modification of the EPA Method 5 sampling train and may be used to determine particulate emission rates from stationary sources. The method is applied to semivolatile compounds, including polychlorinated biphenyls (PCBs), chlorinated dibenzodioxins and dibenzofurans, polycyclic organic matter, and other semivolatile organic compounds. 

The pyrolysis of vinylidene chloride produced a range of chlorinated aromatic compounds including polychlorinated benzenes, styrenes, and naphthalenes (Yasahura and Morita 1988), and a series of chlorinated acids including chlorobenzoic acids has been identified in emissions from a municipal incinerator (Mowrer and Nordin 1987). 

Incineration of domestic waste is also a contributor to environmental pollution. One more source of dioxins is pulp-and-paper industry. Comparatively new ways of forming polychlorinated dibenzo-p-dioxins and furans are high-temperature processes like copper melting in electric arc furnaces, and production of magnesium, nickel and, possibly, other metals of their chlorides. 

The water insoluble, highly chemically and thermally stable PCBs used as insulating fluids for transformers and capacitors, in paints, copy paper, etc., are extremely toxic, persistent in the environment and bioaccumulating. PCBs are currently destroyed by incineration of concentrates at high temperatures or chemically with sodium metals or organosodium. Both processes are costly. The cathodic reduction/elimination of the chlorine from polychlorinated biphenyl... 

POLYCHLORINATED DIBENZODIOXINS AND FURANS AS POLLUTANTS FORMED IN INCINERATIONS... 

The IT Corporation thermal destruction unit is a mobile unit that uses infrared incineration technology. The main objective of this process is to transform the feedstock into another form (an ash acceptable for delisting) while assuring safe discharge of exhaust gas products to the environment. The unit is capable of on-site remediation of wastes and soils contaminated with polychlorinated biphenyls (PCBs) and other organics. This technology is based on a conveyor belt furnace process. 

Transportable incineration systems (TlSs) are rotary kiln incinerators used for the ex situ treatment of soils, sludges, sediments, liquids, and debris contaminated with heavy metals, polychlorinated biphenyls (PCBs), and other hazardous organic substances. 

The electric infrared incineration technology is a mobile thermal processing system that is suitable for soils or sediments contaminated with organic compounds, polychlorinated biphenyls (PCBs), and metals. Liquid organic wastes can be treated after mixing with sand or soil. Electrically powered silicon carbide rods heat organic wastes to combustion temperature while any remaining combustibles are incinerated in an afterburner. 

SFE has also replaced many regulated solvents in analytical chemistry applications in recent years, primarily because it provides a more reliable measure of the concentrations of environmental contaminants and can play an important role in pollution assessment, abatement, and control. Advantages have been shown for using SFE compared to the conventional Soxhlet extraction with toluene for determining the presence of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in ashes from a municipal incinerator (Dolezal et al., 1995). SFE allows the complete extraction of the analytes from the sample, whereas conventional extraction results in an incomplete, and hence, inferior extraction. 

Nadim, L., Schocken, M.J., Higson, F.J., Gibson, D. T., Bedard, D. L., Bopp, L. H. Mondello, F. J. (1987). Bacterial oxidation of polychlorinated biphenyls. In Proceedings of the 13th Annual Research Symposium on Land Disposal, Remedial Action, Incineration, and Treatment of Hazardous Waste, pp. 395—402. U.S. Environmental Protection Agency, Cincinnati, OH (EPA/600/9-87/015). 

At the same time the issues related to the unintentionally produced dioxins and furans, i.e., polychlorinated dibenzo- -dioxins (PCDDs) and PCDFs, attracted public attention in 1983 when investigations revealed that dioxins were detected in the fly ashes from municipal waste incinerators. Therefore, measures to monitor dioxins in the bottom sediment and aquatic animals and plants in the rivers, lakes, marshes and seawaters as well as the atmosphere were initiated in 1986. Investigations were implemented on the actual status of waste incinerators in 1984 and pulp and paper factories in 1990. On the basis of these findings, guidelines and administrative guidance on controlling emissions of dioxin-related chemicals were derived and established. 

Shin, K.-J., Chang, Y.-S., 1999. Characterization of polychlorinated dibenzo-p-dioxins, di-benzofurans, biphenyls, and heavy metals in fly ash produced from Korean municipal solid waste incinerators. Chemosphere 38, 2655-2666. 

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