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The Warsaw Voice » Other » September 16, 2009
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Radiation to Reduce Pollution
September 16, 2009    wersja polska »
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Polish nuclear chemists have come up with an idea to use radiation to treat flue gases generated by power plants.

The process removes sulfur dioxide and nitrogen oxides from the gases and the only by-product is inorganic fertilizer, which can be used in agriculture, say the researchers, who work at the Institute of Nuclear Chemistry and Technology in Warsaw.

A similar technology is used to purify plant and animal materials from microbiological contamination. According to the researchers, ionizing radiation is ideal when other sterilization methods involve excessive temperatures and when it is forbidden to add a specific sterilizing agent to a product.

In June, the Institute of Nuclear Chemistry and Technology unveiled its flagship application technologies at the Innovation Technologies Machines fair in the western city of Poznań.

A beam of accelerated electrons
One of the technologies is based on treating flue gas using a beam of accelerated electrons. The technology is designed to stimulate gas molecules, as a result of which pollutants are oxidized and enter a reaction with water vapor, forming acids that are then neutralized with ammonia. The process also eliminates volatile organic compounds. The solid product of the process is inorganic fertilizer, which is commercially used in vast quantities. Both pollutants-sulfur dioxide and nitrogen oxides-are thus simultaneously removed in a dry process. The technology makes it possible to remove 98 percent of the sulfur dioxide and up to 70 percent of the nitrogen oxides from flue gases. The irradiation process is conducted in two stages. The installation treats flue gases produced by two boilers, each with a capacity of 65MWe.

The project manager is Prof. Andrzej Chmielewski, D.Sc., director of the Institute of Nuclear Chemistry and Technology. For around seven years, the technology has been applied on an industrial scale at the Pomorzany Heat and Power Plant, part of the Dolna Odra Power Generation Group, in Szczecin. The research-and-industry installation was launched under a contract between the International Atomic Energy Agency in Vienna and the governments of Japan and Poland and built as a joint project with the Energy Management and Conservation Agency (EMCA). It is the only installation of its kind in the world.

Investment and operating costs are around 20 percent lower than in conventional processes. This is particularly important in the case of installations built in existing power plants. Although the Polish technology is cheaper, its application would require power plants to invest a lot of money and give up traditional technologies currently in use.

Most traditional methods have been developed in Germany. Popular flue gas treatment technologies include the wet method, which removes sulfur dioxide and produces gypsum.

Radiation without radioactivity
The Center for Radiation Research and Technology is managed by Zbigniew Zimek, D.Sc., while the head of the Radiation Sterilization Laboratory is Iwona Kałuska. The Institute of Nuclear Chemistry and Technology is the only facility in Poland to conduct radiation sterilization involving a stream of high-energy electrons, produced by the Elektronika 10/10 accelerator. The station has been in operation for 20 years.

Medical products and plant and animal materials which undergo radiation processing are toxicologically and bacteriologically safe and retain their properties. The researchers say radiation sterilization does not induce radioactivity in the irradiated product. High-energy electron radiation is also used to sterilize surgical clothes, blood transfusion kits, gynecology kits and microbiological equipment. The institute provides its services to four tissue banks, which use the method to sterilize bone, cartilage and skin grafts. On a smaller scale, the process is used to sterilize therapeutic products, cosmetic preparations and their components.

Whether medicines can be sterilized through irradiation depends on their radiation immunity. Tablets, powders, pastes, ointments and suspensions are less vulnerable to radiation than solutions. Radiation sterilization is less commonly applied to final therapeutic products than raw materials.

Since plant and animal materials frequently contain high amounts of microbiological impurities, ionizing radiation is practically the only acceptable sterilization method, according to the researchers. Other methods necessitate either temperatures that are too high for this kind of products or employ sterilizing agents that are not recommended for use with such products.

Radiation sterilization is an efficient method, the researchers say, because ionizing radiation kills pathogenic microorganisms by causing irreversible damage to the cell membrane and disturbing replication. The main advantages of the method include its simplicity (repeatable parameters, easy monitoring and precise quality control), sterilization conducted at room temperature or lower, and a fast sterilization process. This method can be used on any batch of products and employs totally hermetic packaging, which rules out recurring contamination and makes products safe to the environment, the researchers say.
Piotr Bartosz
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