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, the disposal of polychlorinated biphenyls (PCBs), which had remained in storage for many years in Japan, was a social issue. As temperature control and byproduct control measures became increasingly stringent, there was an urgent need to develop a technology to safely detoxify waste. Against this backdrop, General Giken of Oku-gun, Okayama Prefecture, has developed a new technology to decompose chlorinated organic compounds such as PCBs using a plasma flame generated in an inert gas at 3,000 to 5,000℃. Three treatment methods are supported: instantaneous thermal decomposition of vaporized materials at high temperatures, incineration by plasma, and chemical decomposition with hydrogen and other substances by reacting with oxygen mixed gas. Since molecules can be cut off in a short time, high-speed processing and downsizing of equipment were expected.

General Giken collaborated with electric power companies and heavy equipment manufacturers to put this technology to practical use and proceeded with the development of equipment. At the time, PCB treatment technologies were running in tandem, including photo- and catalytic cracking, alkali-catalyzed BCD, and hydrogen reduction methods, and the plasma method attracted attention as suitable for small-scale dispersed treatment due to its "high temperature blow" characteristics and modular structure. In 2000, just before the tightening of regulations and social demands, this experiment marked the beginning of the shift from storage to treatment, and attracted nationwide interest as an environmental technology originating from the region.