| Blessing and curse of chlorine: |
| The most common disinfectant in drinking-water-treatment is chloric gas |
| Chlorine is a very reactive chemical substance which inherently in only found in compound with other elements.
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| Due to its strong poisonous action, concentrations of three grams of pure chlorine per aerial-cubic meter can already lead to death after a few breaths of air. For this reason the consumptive gas was used on people and mammals in the First World War as the first chemical fighting weapon. |
| On the other hand chlorine is useful for its germicidal qualities and also for human health. The substance is required as a disinfectant in water-treatment as well as swimming-pools. |
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| Use: |
| In current standard indirect chloric gas procedures a chlorine solution is compounded at first, which then is added to the water that needs to be treated. |
| Modern dosing-, measurement-, and control technology permits the application of chlorine without exceeding the limit of 10mg/l trihalogenmethane (haloforms) but at the same time assuring a safe disinfection. |
| In areas where chlorine is not recommended because of the exposed substances in the water (e.g. humic acid) there is an alternative in using chlorine dioxide due to its non-haloform-producing qualities. |
| The dissolving of chloric gas in water leads to a hydrolisis. Underchloric acid and hydrochloric acid are created. In turn, the developed acid is seperated subject to pH-value. |
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| Status quo: |
| Chlorine is the most used disinfectant. However, since 1974 it is known that chlorination of water leads to a development of volatile organic chlorine compounds. |
| These byproducts are created through reactions of loose chlorine with organic material. Most of the known byproducts are so-called trihalomethanes (THM) including chloroform which definitely cause cancer on animals. Chloramin is under suspicion in causing allergies and is reponsible for chlorine odor and pharmacy- or swimming pool – odor of chlorinated water. |
| Countless studies about trihalomethanes implicate a connection between chlorination of drinking- and swimming pool-water and the hightened risk of bladder,- colon-, rectum-, and lung-cancer in people. Due to this a drinking water guideline was passed by the European Community in 1980 which defines a maximum value of 1 microgram per liter for volatile organohalogens. |
| Currently half of the entire drinking water is being chlorinated in the Federal Republic of Germany although there are alternative disinfection-technologies. |
Due to the above named potential risks it is reckoned that the market share of chloric gas disinfection will drop to about 50% in the next five to ten years and will be replaced by other disinfection-methods.
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©2005 WaterVitt |
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