Dechlorination And Reclamation Of PCB-Contaminated Insulating Fluids

A process was developed by Ontario Hydro Research to dechlorinate PCBs in contaminated insulating fluids and reclaim the insulating fluids after treatment, thus alleviating a growing environmental hazard. The contaminated fluids, containing up to several thousand milligrams of PCB per kilogram (ppm) are contacted with metallic sodium at moderate temperatures, resulting in virtual (<2 mg/kg) disappearance of any PCB. Results are presented for a variety of new and aged insulating oils contaminated with either PCB or PCB-containing askarel at concentrations up to 100 000 mg/kg. Details are presented on reaction conditions, type of PCB molecule and insulating oil and oil reclamation processes. Successful operation of the process is described at the laboratory (1 L) as well as the pilot plant (120 L) scale. All process streams were found, free of toxic by- products while after conventional clay treatment the regenerated oils-were suitable for reuse.