Encyclopedia of Environmental Science and Engineering, Volume I and II

PCBs AND ASSOCIATED AROMATICS 927

Incineration

‘Non-Thermal’

Methods

Webber

Catalysis Hydrodechlorination

Molten Salt

IsolationMatrix Vitrification

Off-shore Chlorolysis

Plasma

Pyrolysis

Fluid Wall

Rotary Kilns Reactor

Infra-Red

Systems

Supercritical

Water Oxidation

Cement

Kilns

Diesel

Engines

‘Low’ Temperature

Combustion

Systems

Penberthy

Glass Furnace

‘High’ Temperature

Combustion

Systems

FIGURE 46 Disposal methods for the high concentration PCB fluids.

PCBs even if they are at the several hundred ppm

concentration level. This is because the methods

which are aimed primarily at the decontamina-

tion of low concentration liquids tend to remain

effective up to levels as high as, perhaps, 1%

(10,000 ppm) and, in any case, well into the

range defined by the EPA as “PCB fluid”.

(3) The remediation of PCB contaminated soils can

present a wide range of PCB concentrations for

destruction. This section reviews several different

methods used on a large scale or being developed

for field use and includes an outline of informa-

tion on the application of a novel electrochemical

technology.

It is sometimes possible to reclaim the liquid for re-use.

Several of the numerous alternative chemical methods of

PCB dechlorination as well as physical separation methods

can be made to yield decontaminated liquids.

The stability and lack of reactivity of PCBs are benefits

and at the same time, liabilities. Their thermal stability to oxi-

dation and in the extreme case, combustion, and resistance

to harsh chemicals such as strong acids, bases, oxidizing and

reducing agents, has made the removal of PCBs from electri-

cal and other uses extremely difficult.

The PCB decontamination methods presently available

fall into four major classes and are either physical, physico-

chemical, chemical or biochemical. The literature concerning

PCBs is expanding rapidly. This paper is not intended to be a

complete review of every disposal option, but rather an over-

view of some of the more scientifically interesting systems.

(1) THE DISPOSAL OF PCB LIQUID

PCB liquid is taken to include those commercial PCB mixtures

which were diluted with tri- and tetra-chlorobenzenes and

which typically contain about 70% PCBs. There is an impor-

tant distinction to be made between askarel fluids in which

PCBs are the majority constituent and fluids which contain

more than 500 ppm PCB but in which PCBs are not a majority

component. The EPA requires that any fluid with a concentra-

tion of more than 500 ppm PCB must be considered as a “PCB

fluid”. The name “askarel” is a generic name used for PCB

formulations. Other names found frequently in the literature

are manufacturer’s trade names such as “Aroclor”. “Inerteen”,

“Chlorphen”, “Safe-T-Kuhl”, “Pyrochlor” etc. The most

commonly used askarel in North America was Monsanto’s

“Aroclor” and these two names are often interchanged. Figure 57

shows some of the disposal options available for askarels.

INCINERATION

EPA research into the thermal degradation of PCBs has

involved the use of commercial mixtures and pure isomers

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