THERMAL DESTRUCTION OF PCB AND HEXACHLOROBENZENE

PCB [polychlorinated biphenye] and hexachlorobenzene are considered to be 2 environmental compounds of concern to humans that are most difficult to destroy. Basic data was obtained for appraisal of the risks involved in the thermal destruction of PCB and hexachlorobenzene. It is possible to destroy PCB by incineration provided that the transit time is sufficiently long. In the pilot scale incinerator used, a transit time of more than 2 s was required to obtain a residue of PCB less than 100 mg/kg PCB fed into the incinerator. It was not possible to determine any fixed relationship between the temperature and the PCB residue within the temperature range examined (675-1000.degree. C). Hexachlorobenzene is formed in association with the combustion of PCB and that the rate of formation increases at high temperatures (35 mg HCB/kg PCB at 1000.degree. C). A temperature of 950.degree. C is needed for the destruction of hexachlorobenzene if the residue is to be less than 100 mg HCB/kg HCB. At 800.degree. C, with a transit time of about 2 s, there is a residue of approximately 1200 mg/kg.