Water chlorination

J. C. Morris and R. A. Isaac, Water Chlorination Environmental Impact and Health Effects, Vol. 4, Ann Arbor Science, Ann Arbor, Mich., 1983, pp. 49-62. 

The dissociation of hypochlorous acid depends on the pH. The unionized acid is present in greater quantities in acid solution, although in strongly acid solution the reaction with water is reversed and chlorine is Hberated. In alkaline solutions the hypochlorite ion OCL is increasingly Hberated as the pH is increased. The pH is important because unionized hypochlorous acid is largely responsible for the antimicrobial action of chlorine in water. Chlorine compounds are therefore more active in the acid or neutral range. The hypochlorites most commonly employed are sodium hypochlorite [7681-52-9] or calcium hypochlorite [7778-54-3]. 

Many reagents are able to chlorinate aromatic pyrazole derivatives chlorine-water, chlorine in carbon tetrachloride, hypochlorous acid, chlorine in acetic acid (one of the best experimental procedures), hydrochloric acid and hydrogen peroxide in acetic acid, sulfuryl chloride (another useful procedure), etc. iV-Unsubstituted pyrazoles are often used as silver salts. When methyl groups are present they are sometimes chlorinated yielding CCI3 groups. Formation of dimers and trimers (308 R = C1) has also been observed. 

Oxides of manganese and iron are often found deposited together. Similar conditions cause oxidation of both iron and manganese ions. Exposure to oxygenated water, chlorination, and some microbiological processes causes such oxidation. Often, a few percent chlorine is found in deposits, possibly because of associated chlorination. 

There are three basic terms used in the chlorination process chlorine demand, chlorine dosage and chlorine residual. Chlorine demand is the amount of chlorine which will reduced or consumed in the process of oxidizing impurities in the water. Chlorine dosage is the amount of chlorine fed into the water. Chlorine residual is the amount of chlorine still remaining in water after oxidation takes place. For example, if a water has 2.0 ppm chlorine demand and is fed into the water in a chlorine dosage of 5.0 ppm, the chlorine residual would be 3.0 ppm. 

Water chlorination is carried out by using both free and combined residuals. The latter involves chlorine application to produce chloramine with natural or added ammonia. Anhydrous ammonia is used if insufficient natural ammonia is present in the wastewater. Although the combined residual is less effective than free chlorine as a disinfectant, its most common application is as a post-treatment following free residual chlorination to provide initial disinfection. 

At present, chlorine dioxide is primarily used as a bleaching chemical in the pulp and paper industry. It is also used in large amounts by the textile industry, as well as for the aching of flour, fats, oils, and waxes. In treating drinking water, chlorine dioxide is used in this country for taste and odor control, decolorization, disinfection, provision of residual disinfectant in water distribution systems, and oxidation of iron, manganese, and organics. The principal use of chlorine dioxide in the United States is for the removal of taste and odor caused by phenolic compounds in raw water supplies. 

Table 3.3.5-2 Partial FMEA for the Coolins Water Chlorination System...

Partial FMEA for the Cooling Water Chlorination System. 

Water fluoridation d Saccharin d Water chlorine d Water chlorination d Oral contraceptives d Valium d... 

Benzofuroxan may be obtained by oxidation of o-quinone dioxime. The first benzofuroxan derivative, 1,2-naphthofuroxan, was obtained by this method. Suitable oxidizing agents include alkaline ferri-cyanide, bromine water, chlorine, and nitric acid. The method is of practical value only when the o-quinone or its monooxime (o-nitrosophenol) is readily available, and since this is not generally the case, other routes, e.g., the oxidation of o-nitroanilines and the thermal decomposition of o-nitrophenyl azides/ are more commonly used. 

Ethylene reacts by addition to many inexpensive reagents such as water, chlorine, hydrogen chloride, and oxygen to produce valuable chemicals. It can be initiated by free radicals or by coordination catalysts to produce polyethylene, the largest-volume thermoplastic polymer. It can also be copolymerized with other olefins producing polymers with improved properties. Eor example, when ethylene is polymerized with propylene, a thermoplastic elastomer is obtained. Eigure 7-1 illustrates the most important chemicals based on ethylene. 

Note the resistivity of sea-water drops as the chlorinity and temperature rise and in open sea-water (chlorinity l9 /o) it varies from about 160 cm in the tropics to 350 cm in the Arctic. 

The pH of the water is checked again and made slightly basic to reduce acid corrosion of the pipes. At this point, a disinfectant, usually chlorine, is added. In the United States, the chlorine level is required to be greater than 1 g of Cl2 per 1000 kg (1 ppm by mass) of water at the point of consumption. In water, chlorine forms hypochlorous acid, which is highly toxic to bacteria ... 

Keith LH, Hall RC, Hanisch RC, et al. 1983. New methods for gas chromatographic analysis of water pollutants. In Jolley RE, Brungs WA, Cotruvo JA, et al., eds. Water chlorination Environmental impact and health effects. Vol. 4(Bookl Chemistry and water treatment), Ann Arbor Science. Ann Arbor, MI The Butterworth Group, 563-582. 

Pyrene is a common PAH contaminant and may occur in drinking water. Chlorination of water with or without bromide that may be present in coastal environments has been examined. Both chlorinated and brominated pyrenes with halogen substituents at the 1,3-, 1,6-, and 1,8-positions were found, and could putatively be produced by reaction of pyrene with hypochlorous acid and hypochlorite (Hu et al. 2006). 

Please indicate which six of the following issues are the most important when considering the comfort and well-being of users and staff. (Air temperature, bacteria, chloramine levels in the water, chlorinous smells, clear water, fresh air, humidity, pH, residual disinfectant level, trihalomethanes, water temperature, water balance)... 

Sodium is a very reactive metallic element for example, it liberates hydrogen gas when treated with water. Chlorine is a yellow-green, choking gas, used in World War I as a poison gas. Contrast these properties with those of the compound of sodium and chlorine—sodium chloride—known as table salt. 

Carpenter JH, Smith CA in Water Chlorination - Environmental Impact and Health Effects Jolley RL, Gorchev H, and Hamilton DH (eds) Volume 2 (1978) Ann Arbor Science, Ann Arbor, MI, p. 195-208... 

LINE/VESSEL Cooling Water Chlorination System DATE December 22, 1992 PAGE of... 

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