What is the main disposal method for Polychlorinated biphenyls (PCBs)?

The primary disposal method for Polychlorinated biphenyls (PCBs) is through incineration and landfilling. Incineration is widely used as it effectively destroys PCBs, reducing them to non-toxic substances and minimizing their environmental impact. High-temperature incineration destroys the chemical structure of PCBs, effectively eliminating their hazardous nature.

Landfilling is utilized for PCBs that cannot be incinerated under certain conditions. It involves securing the waste in a controlled environment to prevent its leaching into the surrounding soil and groundwater. Landfilling is often used in conjunction with other treatment methods to ensure thorough disposal while averting environmental contamination.

Other methods listed either do not effectively eliminate PCBs or are not suitable for the levels of toxicity associated with these compounds. For instance, in situ vaporization is not commonly employed as it may not sufficiently mitigate PCB contamination. Biodegradation, while a valuable method for some hazardous waste, is generally not effective for PCBs due to their stable and persistent nature. Soil washing can remove some contaminants from soil but may not adequately address the toxicity and stability issues related to PCBs. Therefore, incineration and landfilling remain the most reliable methods for PCB disposal.