Organic chlorine cut with a high-temperature blade--Oku-gun, Okayama Prefecture, 2000

Organic chlorine cut with a high-temperature blade--Oku-gun, Okayama Prefecture, 2000

At the end of the 1990s, a social issue in Japan was how to proceed with the disposal of polychlorinated biphenyls (PCBs), which had been stored and left unattended for many years and had become a problem. Highly concentrated PCBs are difficult to control the temperature of incineration and to prevent byproducts, and while stable storage continued in many areas, there was an urgent need to establish dedicated detoxification technology and equipment. In this context, General Giken of Oku-gun, Okayama Prefecture, presented a process for vaporizing and decomposing chlorinated organic compounds such as PCBs using a "3,000 to 5,000°C plasma flame generated in an inert gas" (in an inert atmosphere such as argon). (Under an inert atmosphere such as argon, the process can be used in three ways: 1) high-speed thermal decomposition of vaporized materials with a plasma flame, 2) incineration with a plasma flame, and 3) chemical decomposition with hydrogen and other substances by reacti
ng with an oxygen gas mixture. This concept aims to cut off persistent molecules at extremely high temperatures and short dwell times, and to make the process smaller and faster. For implementation, the company has even made arrangements with electric power companies and heavy equipment manufacturers to begin development of the equipment.

At the time, there were competing technological approaches to "burn, melt, or reduce," with photo- and catalytic decomposition, the alkali-catalyzed BCD method, and the hydrogen reduction method running side by side. The plasma method was considered to have advantages in that it could proceed with a reaction in a single blow at high temperature and that it was easy to modularize the equipment, and its potential application to small-scale dispersion processing attracted attention. In 2000, just prior to the tightening of regulations and the increase in social demands, General Giken's attempts marked the beginning of the transition from the "storage era" to the "processing era," a technological trend that originated in the region.