16593 14 tủ tài liệu bách khoa
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16593 14 tủ tài liệu bách khoa
CHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoa a process designed for the deliberate reduction of the number of pathogenic microorganisms. While other water treatment processes, such as filtration or coagulalion-flocculalion-sedinienlalion. may achieve pathogen reduction, this is not generally their primary goal. A variety of chemical or physic 16593 14 tủ tài liệu bách khoaal agents may be used to carry out disinfection.The concept of disinfection preceded the recognition of bacteria as the causative agent of disease. Av16593 14 tủ tài liệu bách khoa
erill (1832). for example, proposed chlorine disinfection of human wastes as a prophylaxis against epidemics. Chemical addition during waler treatmentCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoarent, particularly with respect to the reduction of typhoid and cholera.While significant progress is being made in controlling the classic waterborne diseases, newly recognized agents have added to the challenge. These include viruses (Melnick Ct al.. 1978: Mosley. 1966). certain bacteria (Campylob 16593 14 tủ tài liệu bách khoaacter, Palmer Ct al., 1983; Yersinia, Brennhovd el al., 1992; Reasoner. 1991; or Mycobacteria, Geldreich. 1971: livanainen Ct al.. 1993: Reasoner. 19916593 14 tủ tài liệu bách khoa
1: for example), and protozoans (Giardla, Brown et al., 1992; Le Chevallier el al., 1991; Miller el al., 1978: Reasoner, 1991; Renton et al., 1996; RoCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoa96: Hayes el al., 1989: Le Chevallier el al., 1991: Leland et al., 1993; Mac Kenzie el al., 1994: Miller. 1992: Reasoner. 1991: Richardson et al.. 1991: Rose Ct al.. 1991: Rush Ct al.. 1990: Smith, 1992). Occasional outbreaks of drinking-water-associated hepatitis have also occurred (Nasser. 1994: R 16593 14 tủ tài liệu bách khoaosenberg Ct al., 1980). In addition, new viral agents arc continually being found to be capable of waterborne transmission.The state of disinfection p16593 14 tủ tài liệu bách khoa
ractice in the United Stales in the late 1980s was summarized in a survey of the AWWA Disinfection Committee (Haas et al.. 1992). Most water utilitiesCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoa pre- or postammoniation) or chlorine dioxide or ozone. With the increasing concern fnr rpnmvinrr nnd imrl ivnt inn enmp rU* fhx» mnrp r^cicf'.int 11'1 thriíT^ne cnrh C1C Í tirtrslirt14.2CHAPTER FOURTEENTABLE 14.1 Water Utility Disinfection Practices According to 1989 AWWA Survey (.v = 267)No ammoni 16593 14 tủ tài liệu bách khoaaAmmoniaChlorine aloneGas67.42%19.85%Hypochlorite5.99%0.75%Chlorine + CIO23.37%1.50%Ozone0.37%Other0.75%Source: Haas el al.. 1992.traditional chlorina16593 14 tủ tài liệu bách khoa
tion arc gaining popularity. Illis chapter will cover the use of chlorine, as well as the major alternative agents, for the purpose of disinfection.HICHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoalav and McBee. 1966). Early uses of chlorine included the use of Javcllc water (chlorine gas dissolved in an alkaline potassium solution) in France for waste treatment in 1825 (Baker. 1926) and its use as a prophylactic agent during the European cholera epidemic of 1831 (Bclohlav and McBee. 1966).Di 16593 14 tủ tài liệu bách khoasinfection of water by chlorine first occurred in 1908 at Bubbly Creek (Chicago) and the Jersey City Water Company. Within two years, chlorine was int16593 14 tủ tài liệu bách khoa
roduced as a disinfectant at New York City (Croton). Montreal. Milwaukee. Cleveland. Nashville. Baltimore, and Cincinnati, as well as other smaller trCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoating more than 3 billion gal/day (l.lxl 0 mVday) of water, were employing chlorine as a disinfectant (Race. 1918).Chloraminalion, the addition of both chlorine and ammonia either sequentially or simultaneously, was first employed in Ottawa. Canada, and Denver, Colorado, in 1917. Both of these early 16593 14 tủ tài liệu bách khoaapplications employed prcrcaction of the two chemicals prior to their addition to the full flow of waler. Somewhat later, preammoniation (the addition16593 14 tủ tài liệu bách khoa
of ammonia prior to chlorine) was developed. In both cases, the process was advocated for its ability to prolong the stability of residual disinfectaCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoa. and recognition of the superiority of free chlorine as a disinfectant, reduced the popularity of the chloramination process. Recent concerns about organic by-products of chlorination, however, have increased the popularity of chloramination (Wolfe el al., 1984).Chlorine DioxideChlorine dioxide was 16593 14 tủ tài liệu bách khoa first produced from the reaction of potassium chlorate andDISINFECTION14.3Chlorine dioxide has been used widely as a bleaching agent in pulp and pape16593 14 tủ tài liệu bách khoa
r manufacture (Rapson. 1966). Despite early investigations on the use of chlorine dioxide as an oxidant and disinfectant (Aston and Synan. 1948). howeCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoan used extensively for water disinfection."By 1977.84 potable water treatment plants in the United States were identified as using chlorine dioxide treatment, although only one of these relied upon it as a primary disinfectant (Miller el al., 1978). In Europe.chlorine dioxide was being used as eithe 16593 14 tủ tài liệu bách khoar an oxidant or disinfectant in almost 500 potable water treatment plants (Miller el al.. 1978).OzoneOz.one was discovered in 1783 by Van Marum.and na16593 14 tủ tài liệu bách khoa
med by Schonbein in 1840. In 1857. the first electric discharge ozone generation device was constructed by Siemens, with the first commercial applicatCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoashoorn. Netherlands. In 1906. Nice. France, installed ozone as a treatment process, and this plant represents the oldest ozonation installation in continuous operation (Rice Ct al., 1981). In the United Stales, ozone was first employed for taste and odor control at New York City's Jerome Park Reserv 16593 14 tủ tài liệu bách khoaoir in 1906. In 1987. five water treatment facilities in the United Slates were using ozone oxidation primarily for taste and odor control or trihalom16593 14 tủ tài liệu bách khoa
elhane precursor removal (Glaze. 1987). Since the 1993 Milwaukee Cryptosporidium outbreak, there has been an upsurge in interest in ozone as a disinfeCHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is 16593 14 tủ tài liệu bách khoa for microbial decay often associated with sunlight (Downes and Blount. 1877). By the early 1940s, design guidelines for uv disinfection were proposed (Huff Ct al., 1965). uv has been accepted for treating potable water on passenger ships (Huff Ct al.. 1965). Historically, however, it has met with l 16593 14 tủ tài liệu bách khoaittle enthusiasm in public waler supply applications because of the lack of a residual following application. In wastewater treatment, in contrast, ov16593 14 tủ tài liệu bách khoa
er 600 plants in the United States are either using, currently designing, or constructing uv disinfection facilities (Scheible Ct al.. 1992).CHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection is CHAPTER 14DISINFECTIONCharles N. Haas, Ph.D.LD Betz Professor of Environmental Engineering Drexel UniversilyPhiladelphia, PennsylvaniaDisinfection isGọi ngay
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