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Water chlorination is the process of adding chlorine () or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc. ==History== In a paper published in 1894, it was formally proposed to add chloride to water to render it “germ-free.” Two other authorities endorsed this proposal and published it in many other papers in 1895. Early attempts at implementing water chlorination at a water treatment plant were made in 1893 in Hamburg, Germany, and in 1897 the town of Maidstone, England was the first to have entire water supply treated with chlorine. Permanent water chlorination began in 1905, when a faulty slow sand filter and a contaminated water supply led to a serious typhoid fever epidemic in Lincoln, England. Dr. Alexander Cruickshank Houston used chlorination of the water to stem the epidemic. His installation fed a concentrated solution of chloride of lime to the water being treated. The chlorination of the water supply helped stop the epidemic and as a precaution, the chlorination was continued until 1911 when a new water supply was instituted.〔Reece, R.J. (1907). “Report on the Epidemic of Enteric Fever in the City of Lincoln, 1904-5.” In Thirty-Fifth Annual Report of the Local Government Board, 1905-6: Supplement Containing the Report of the Medical Officer for 1905-6. London: Local Government Board.〕 The first continuous use of chlorine in the United States for disinfection took place in 1908 at Boonton Reservoir (on the Rockaway River), which served as the supply for Jersey City, New Jersey.〔Leal, John L. (1909). “The Sterilization Plant of the Jersey City Water Supply Company at Boonton, N.J.” ''Proceedings'' American Water Works Association. pp. 100-9.〕 Chlorination was achieved by controlled additions of dilute solutions of chloride of lime (calcium hypochlorite) at doses of 0.2 to 0.35 ppm. The treatment process was conceived by Dr. John L. Leal, and the chlorination plant was designed by George Warren Fuller.〔Fuller, George W. (1909). “Description of the Process and Plant of the Jersey City Water Supply Company for the Sterilization of the Water of the Boonton Reservoir.” ''Proceedings'' AWWA. pp. 110-34.〕 Over the next few years, chlorine disinfection using chloride of lime were rapidly installed in drinking water systems around the world.〔Hazen, Allen. (1916). ''Clean Water and How to Get It.'' New York: Wiley. p. 102.〕 The technique of purification of drinking water by use of compressed liquefied chlorine gas was developed by a British officer in the Indian Medical Service, Vincent B. Nesfield, in 1903. According to his own account, "It occurred to me that chlorine gas might be found satisfactory ... if suitable means could be found for using it.... The next important question was how to render the gas portable. This might be accomplished in two ways: By liquefying it, and storing it in lead-lined iron vessels, having a jet with a very fine capillary canal, and fitted with a tap or a screw cap. The tap is turned on, and the cylinder placed in the amount of water required. The chlorine bubbles out, and in ten to fifteen minutes the water is absolutely safe. This method would be of use on a large scale, as for service water carts.” Major Carl Rogers Darnall, Professor of Chemistry at the Army Medical School, gave the first practical demonstration of this in 1910. This work became the basis for present day systems of municipal water ''purification''. Shortly after Darnall's demonstration, Major William J. L. Lyster of the Army Medical Department used a solution of calcium hypochlorite in a linen bag to treat water. For many decades, Lyster's method remained the standard for U.S. ground forces in the field and in camps, implemented in the form of the familiar Lyster Bag (also spelled Lister Bag). Chlorine gas was first used on a continuing basis to disinfect the water supply at the Belmont filter plant, Philadelphia, Pennsylvania by using a machine invented by Charles Frederick Wallace who dubbed it the Chlorinator. It was manufactured by the Wallace & Tiernan company beginning in 1913.〔http://library.rit.edu/findingaids/Inventories/WallaceAndTiernanCompanyRecords.pdf〕 By 1941, disinfection of U.S. drinking water by chlorine gas had largely replaced the use of chloride of lime.〔Baker, Moses N. (1981). ''The Quest for Pure Water: the History of Water Purification from the Earliest Records to the Twentieth Century.'' 2nd Edition. Vol. 1. Denver: American Water Works Association. p. 341-342.〕 Chlorination can also be practiced using sodium hypochlorite or various other chemicals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Water chlorination」の詳細全文を読む スポンサード リンク
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