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Activated carbon is a porous carbon made from vegetable carbonaceous material or charcoal. The large number of microscopic pores in activated carbon allow for a surface area of up to 1,000 square meters per gram, which gives it an extremely high adsorption capacity for substances. This property has been used in a wide range of applications, from removing odors in home refrigerators to removing water pollution at water purification plants. Demand for this activated carbon is rapidly increasing due to its high adsorption capacity for dioxin. This report will focus on the emerging needs for water purification, housing materials, and other applications, in addition to its connection with dioxin, which is the focus of much attention.

The market for activated carbon for dioxin is approximately 5 billion yen per year. The first catalyst for increased demand for activated carbon was the 1993 major revision of the Water Quality Standards Law for Water Supply. In response, local governments around the country have been upgrading treatment methods, such as increasing the use of activated carbon, as a measure to remove foul odors and improve water quality. In December 1996, the Environment Agency established new guidelines for dioxin. In August 1997, it was decided to partially revise the Air Pollution Control Law as a measure against dioxin, and the standard values established in the revised Air Pollution Control Law to be enforced from December 1997 are 0.1 nanogram for newly constructed incinerators and 0.5 to 1 nanogram for existing incinerators, which are comparable to the values in Europe and the United States. This has led to a surge in business around dioxin, including measurement and analysis, new incin
erators, and dioxin decomposition technology. Activated carbon has also begun to attract much attention as a removal system that can be applied to existing incinerators.

Powdered activated carbon is used to remove dioxin. Powdered activated carbon is blown into the flue of the incinerator by air to absorb dioxin, and the activated carbon is collected with fly ash by bag filters. The dioxin-absorbed activated carbon is immobilized and detoxified to prevent it from leaching out again. The key to using activated carbon is that there is no need to build a new incinerator or install expensive auxiliary equipment. It can be utilized in existing incinerators, and is easy and effective immediately. It is estimated that activated carbon can reduce dioxin emissions to 10~20% of those without treatment. For a waste incineration facility with a capacity of 100 tons per day, the injection amount is 50 kilograms per day. Since there are approximately 2,000 incinerators in Japan, the market size is estimated to be around 5 billion yen.

Among activated carbon sales companies, Kurita Water Industries was the first to move quickly. In January 1997, the company concluded an exclusive domestic sales contract for activated carbon for dioxin removal with Japan NORIT Corporation, a Japanese subsidiary of NORIT (Netherlands), which has the world's largest activated carbon production capacity. Kurita Water Industries began its dioxin analysis business in 1992 and has been working on dioxin removal technology using activated carbon since the following year, 1993. In the process, the company has conducted tests of NORIT's products at more than 30 waste incineration facilities in Japan and confirmed their effectiveness. The sales target is 500 million yen in the first year and 1.5 billion yen in three years.

Mitsubishi Chemical has more than 20 years of experience in the manufacture of granular activated carbon. The company has consistently increased demand for activated carbon for use in water purification plants, and in April 1997 began selling activated carbon for dioxin adsorption. While the company provides powdered activated carbon for blowing into existing furnaces, it also expects demand for pellet-type activated carbon for use in moving-bed incinerators, since new furnaces can be freely designed in accordance with the strict guidelines of the Ministry of Health and Welfare. The company expects to sell 3,000 tons per year by 2000, worth 600 million yen.

Among incinerator manufacturers, EBARA is enthusiastic about the introduction of activated carbon. The company has developed its own granular and powdered activated carbon, Evadiaya, and has established dioxin reduction technology using it. The company has also made it possible to detoxify waste activated carbon after dioxin adsorption using a decomposition device with a dioxin decomposition efficiency of 95% or higher, and to merge treatment with other fly ashes. Other notable companies include Unitika, which has introduced dioxin adsorption technology using granular activated carbon from German engineering company WKV, and Kuraray Chemical, a comprehensive activated carbon manufacturer.

In addition to dioxin countermeasures, demand for activated carbon is increasing. In the water treatment field, as mentioned above, the revision of the Water Quality Standards Law is providing a tailwind. Activated carbon manufacturers in this field are working to increase supply capacity and establish activated carbon regeneration sites. In the activated carbon regeneration process, granular activated carbon used in advanced treatment at water purification plants is recycled through calcination and other regeneration technologies. Mitsubishi Chemical, Toyo Falgon, EBARA, and other manufacturers are already engaged in the recovery and recycling of activated carbon. The effectiveness of activated charcoal as a soil conditioner has long been known; it was registered as a soil conditioner in 1986. Charcoal helps propagate VA-root fungi, which act on plant roots, and activated charcoal in particular naturally regulates temperature, acidity, humidity, and other factors to produce
a good crop. Powdered activated charcoal is mainly used as a soil conditioner. In addition, a new application that is attracting attention is the use of activated carbon as a material for housing. By placing activated carbon under the floors of houses, it can control humidity and insects, as well as neutralize harmful chemicals emitted from housing materials, such as formaldehyde, which has become a problem in recent years. Ecotech Corporation (Matto City, Ishikawa Prefecture, 076-274-3040) sells houses that use activated carbon throughout the house as "healthy housing. The company promotes the use of activated carbon as a building material not only in homes, but also in the kitchens of stores, which are plagued by odors and other problems, and the use of activated carbon has been well received. Activated carbon has such a wide range of applications, and demand for activated carbon is expected to increase. The activated carbon manufacturing technology was mentioned in the "D
ryer Special" in Issue No. 38 of this magazine. The Tokyo Metropolitan Institute of Industrial Technology has also developed a technology to activate old shinka and a recycling technology to convert pruning branches and waste tires from parks into activated carbon.

Low-pollution versions of equipment are also being developed. Actream Lata (Kanazawa City, Ishikawa Prefecture), a manufacturer of industrial waste treatment plants, developed a low-pollution activated carbon production plant in May 1997. The plant employs a high-frequency heating system, which produces less CO2 than combustion heating using burners, and has succeeded in reducing overall exhaust gas emissions to one-tenth of conventional levels. The company will conduct sales activities targeting activated carbon manufacturers in Japan and overseas. Three models with annual production capacities of 100, 500, and 1,000 tons are being commercialized, and the 1,000-ton type is expected to cost 250 million yen including peripheral equipment. Activated carbon is rapidly attracting attention in the wake of the dioxin problem, but demand is steadily increasing for applications other than dioxin. Activated carbon will continue to be utilized as an old and new material.