|9. Methods for Dismantling PCB-Containing Devices and Method for Treatment of PCB-Contaminated Soil|
Dismantling of vehicle power transformers that use PCB and the treatment of soil/ballast have remained a challenge even for the treatment plant being planned by the Japan Environment Corporation (JEC). This study proposes methods for dismantling vehicle power transformers and treating soil/ballast, and demonstrates that these methods can be applied at low cost.
Using actual vehicle power transformers, methods of cutting the outside plate and dismantling the inside were examined (Fig.1). The results verified that approximately 95% of the insulating oil could be extracted by tilting the power transformer and efficiently directing the insulating oil to the outlet by changing the direction of tilt. A milling machine was used to cut an outside plate to demonstrate that this can be done safely in a short time. Based on the above results, a dismantling manual was created and a method of dismantling vehicle power transformers was proposed to the JEC.
For PCB-contaminated soil, a method of making PCB harmless was attempted by extracting it from the soil using isopropyl alcohol (IPA) and irradiating the extracted liquid with ultraviolet rays. The results demonstrated that the PCB contained in the extracted liquid decomposed up to 0.021mg/kg, well below the effluent standard of 0.5mg/kg. This method requires smaller equipment than that used in conventional bioremediation treatment, and compared with other chemical treatment processes also allows easy soil decontamination using cost-effective equipment (Fig.2).