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Release: December 9, 1999

NGK DEVELOPS WATER TREATMENT SYSTEM FOR REMOVING DIOXIN EMISSIONS

NGK Insulators, Ltd. (President: Masaharu Shibata, Head Office: Nagoya) has developed a water treatment system that effectively decomposes and removes chemicals like dioxin.

In July 1999, the Japanese Diet approved a bill to reduce dioxin emissions and a dioxin control law is expected to become effective in January 2000. The Environment Agency has proposed water quality standards for dioxin which limits contamination to 1 picogram (one-trillionth of a gram) per liter in rivers, streams, lakes, marshes and sea water; and 10 picograms per liter in the waste water of refuse-incineration facilities and final disposal spaces. When the law becomes effective, Environment Agency officials will be empowered to inspect facilities and demand documentation.

The newly developed water treatment system is attached to catalyzer-ozone equipment for dioxin removal. This equipment is constructed with a reacting tower filled with catalyzer and a ozone generator that produces ozone from oxygen in the air. The catalyzer - manganese dioxide -is brazed onto a porous ceramic substrate. Active radical species produced from ozone are dissolved into the waste water and oxidize and remove the dioxin group.

• Mechanism of dioxin decomposition
  Manganese dioxide works as a catalyst to generate highly reactive radical species which then oxidize dioxin into non-toxic byproducts.
• Active radical species
  These are unstable molecules or atoms that have unpaired electrons. The process by which they take electrons away from other molecules to become stable is oxidization.

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Features of Catalyzer-Ozone System for Dioxin Removal

1. Removes dioxin effectively: The strongly oxidizing active radicals easily denature dioxin, thereby reducing dioxin concentration to less than 0.1 picogram per liter.
2. Reduces COD: The active radicals oxidize, decompose and reduce COD with its strong oxidizability and are expected to reduce environmental hormones.
   (COD [Chemical Oxygen Demand]: Indicator which expresses the level of water pollution using organic substance)

1. Reduces Cost of Refuse Treatment: Compared to conventional systems which use oxidizing agents such as hydrogen peroxide and ultraviolet light, this new system is less expensive to construct and operate (no chemical cost) and it reduces electricity cost since it doesn't require use of an oxidizing agent or ultraviolet light.
2. Excellent durability: With a life expectancy of more than 10 years, long- term use without maintenance is possible.
3. Easy Operational Control: The system is simple and can be automatically operated because there is only the ozone generator. This contrasts with older systems using ultraviolet lamps which required cleaning, replacement and disposal of lamps.

NGK's goal in the near future is 5 billion yen in annual sales of landfill leachate treatment system at waste disposal facilities. Furthermore, we will expand business into systems for the removal of microdose toxic agents such as dioxin, environmental hormones and COD's in sewage and industrial liquid waste.

cutaway of catalyzer-ozone equipment for dioxin removal