PCB Disposal and Destruction Technology
Polychlorinated Biphenyls (PCBs) are extremely stable compounds possessing excellent dielectric properties. PCBs were widely used in electric equipment until the 1970s when their use was prohibited due to environmental concerns. Most PCBs have since been removed from service and put into storage. However, the long-term storage of large quantities of hazardous materials poses potential problems. Many jurisdictions have enacted regulations to prevent the indefinite storage.
United Nations Environmental Program (UNEP) has identified PCBs as one of the twelve Persistent Organic Pollutants (POPs) requiring urgent global actions to reduce and eliminate.
PCB Disposal Solutions
Many methods have been proposed and used for PCB disposal, with incineration being one of the most prevalent options. However, incineration is an energy intensive non-selective method and increases the risk of forming more toxic by-products. For this reason, only approved, specially designed incinerators may be used. In many countries, the destruction of PCB by incineration has been banned completely. Other technologies, such as plasma arc, hydrogenation or supercritical water are also non-selective and require high energy inputs.
In the 1980s, Powertech invented and commercialized an efficient and environmentally friendly process for the selective dispersion of PCB in transformer oil. The patented process is based on the use of sodium dispersion of PCB at low temperature. The process has been used by BC Hydro and licensed to others. Since 1987, BC Hydro has decontaminated over 15 million litres of transformer oil. Because the Powertech process is selective, it does not destroy the transformer oil. Most of this processed oil was sold as reclaimed oil and returned to service. This further lowers the overall cost of the Powertech process.
Powertech has expanded the capability of its PCB disposal and destruction technology to include contaminated solids. The first application of this technology is the construction of a plant by BC Hydro to decontaminate fluorescent light ballast potting compound and small capacitor windings. These are the by-products from the replacement of fluorescent light fixtures, e.g., from energy efficiency programs.
To further improve the economics of the sodium process, Powertech also developed the process for manufacturing high quality sodium dispersion from sodium metal ingots and transformer oil.
The Powertech process uses sodium dispersion as the active ingredient for PCB disposal. The sodium reacts with the chlorine atoms in the PCB to form salt and biphenyl. Both these products are non-toxic. The reaction is carried out at temperature and at conditions not conducive for the formation of the highly toxic dioxins and furans. Since the bulk of the feed material, i.e., transformer oil or potting compound, is not destroyed in the process, the material may be recycled or reused. For example, processed transformer oil at BC Hydro is reclaimed in a conventional reclamation plant to new oil specifications and reused or sold.
The Powertech process has received government approvals in Canada and Japan.
Kobelco Eco-Solutions Co. Ltd. is the exclusive licensee for the Powertech PCB destruction technology in Japan and South Korea.