Disinfection treatment methods chlorination

Phenols The term phenols is used to designate a series of hydroxyl derivatives of benzene, with phenol as the parent compound. These compounds come from paper mills and cellulose factories as well as from degradation of pesticides such as carbaryl. Disinfecting treatments of chlorine-containing waters produce chlorophenols, which cause a persistent taste. Analytical control of these compounds is commonly performed by chromatographic or photometric methods. 

Drinking water has been disinfected with chlorine for approximately 100 years to protect against waterborne infectious diseases. In addition to chlorination, other methods of drinking water disinfection include the use of chlorine dioxide (either alone or in combination with chlorine), the addition of ammonia to chlorine to form chloramines, ozone treatment, oxidation with potassium permanganate, and ultraviolet radiation. Chlorination, however, is by far the most widely used method. Treatment with chlorine has virtually eliminated cholera, typhoid, dysentery, hepatitis A, and other waterborne diseases)54 ... 

When there is less control over raw water quality, such as when the supply is downstream of several towns already using a river, or when the natural supply from a groundwater source is poor, more complicated treatment methods are required (e.g.. Fig. 5.1). Following the preliminary treatment steps outlined in the following paragraphs, filtration plus chlorination, or chlorination alone can be used to disinfect the finished supply. When filtration is not used to supplement disinfection, the U.S. EPA recommends that two different disinfection methods be used to ensure supply safety, (e.g., uv irradiation and chlorination). 

Treated wastewater from municipal sewage plants requires a treatment with chlorine before discharge into a river, at least in the warmer months of the year. Because the residual chlorine can kill the flora and fauna of the river, the treated wastewater is usually treated further with sulfur dioxide or sodium bisulfite to remove the chlorine.128 This seems like an ideal place to use alternative methods of disinfection, because no residual activity is needed or desired. Disinfection with ultraviolet light is now a viable alternative.129... 

Despite its toxicity and potential for nefarious use, chlorine continues to be widely used in manufacturing and as a disinfectant. Currently, treatment for chlorine inhalation is largely supportive and nonspecific. Research continues into elucidating chlorine s mechanism of action and into finding methods to mitigate its toxic effects. 

In one procedure that has been widely used, the sample, after suitable treatment, is refluxed with sodium and isopropyl alcohol, after which the solution is diluted with water and the inorganic chloride is determined by standard methods (13, 54) The method has been adopted by the Association of Official Agricultural Chemists 29, 30) as a tentative one for technical DDT and for dusts, oil solutions, and aqueous emulsions of DDT, for use in the absence of other chlorine-containing compounds. The National Association of Insecticide and Disinfectant Manufacturers has also accepted the total-chlorine method for the analysis of these preparations 28). Essentially the same procedures have been described by Donovan 22), of the Insecticide Division of the Production and Marketing Administration, for technical DDT and various commercial DDT products containing no other compounds interfering with the chlorine determination. 

The first level of treatment, with sand filters and chlorination to remove suspended matters and disinfection of pathogens, may be good enough for the low-cost water. The removal of discoloration and bad smell is accomplished by activated charcoal absorption. Ozone and ultraviolet treatments are much more expensive for the removal of microbes and organic matter, and should be considered only when necessary to solve a technical problem, or to satisfy an advertisement need. Reverse osmosis is the most effective method used to recover clean water from brackish water, and to remove inorganic minerals such as sodium, copper, iron, and zinc. The removal of calcium and magnesium ions can be accomplished by the method of ion exchange with sodium, which would also increase the sodium concentration, and could cause objections. Different levels of treatment require a variety of costs, and can produce different levels of customer satisfaction. 

Fem complexes were reported as effective photocatalysts for oxidation of many different organic pollutants, eg alcohols and their derivatives [20,29] organic acids, such as formic [50,53,56], oxalic [37], citric [57], and maleic [58] EDTA [11,20-23], phenol and its derivatives [35, 36, 45,59,60], other aromatic pollutants [38,43,51, 61-64], non-biodegradable azo dyes [40, 41, 48, 55, 59, 65], herbicides [54, 66-70], pesticides [32, 46, 71, 72], insecticides [44], pharmaceuticals and wastewater from medical laboratories [39,47,73], chlorinated solvents [33,74], municipal wastewater [75], and many others [20], The photo-Fenton process was explored as photochemical pre-treatment to improve its biodegradability, especially of biorecalcitrant wastewater from the textile industry [76, 77] the method was also proposed for water disinfection [78,79],... 

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