Potable water chloramination

Secondary disinfectants provide an essential residual that prevents regrowth in the distribution system. Although chlorine is the most widely used secondary disinfectant, chlorine dioxide and monochloramine are appropriate as well. As secondary disinfectants, chlorine and chlorine dioxide are handled in the same manner as for primary disinfectants. The use of monochloramine as a secondary disinfectant is discussed in detail in this section. 

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Potable Water Chlorination Potable Water Chloramination... 

Grinwalla et al.(22) examined the reaction of Suwannee River fulvic acids with chloramine using solution NMR. They report, that while chloramine itself may not form nitrogen containing moieties with Suwannee River fulvic acid, under the conditions examined, the chlorination coproduct, ammonia, most certainly does. They explain that the assertion that chloramine is a safe replacement to chlorine in the treatment of potable water supplies should be tempered, at least until the toxicity of aminated and chlorinated humic products are examined."... 

Chloramination process can be applied to both water treatment and wastewater treatment (1,29). In the field of potable water treatment, chloramine is recommended as a secondary disinfectant because it is ineffective as a virucide, and is only marginally effective against Giardia cysts. It is formed from the combination of ammonia and chlorine (hypochlorite or hypochlorous acid). The chemical is generated on site, usually by injecting ammonia gas or adding an ammonium sulfate solution to chlorinated water. 

This chapter only discusses the applications of chlorination and chloramination in potable water treatment. In case the two processes are to be used for wastewater treatment, residual chlorine concentration in the plant effluent may become a regulatory issue (30). Selection of an alternative disinfectant becomes more important. New alternative disinfectants have been studied by Wang (19-25). Wang (35,36) also reported that UV is an effective process for dechlorination, dechloramination, or de-ozonation. 

Potable Water Chlorination and Chloramination chapter introduces the detailed engineering procedures for calculation of CT values for disinfection, and both conventional and innovative process equipment, including the on-site chlorine gas and hypochlorite generation facilities (2). 

Chlorine has been used as a disinfectant in potable water systems for over 100 yr. Free chlorine and combined chlorine (chloramines) are the two forms of chlorine widely used for the disinfection. Free chlorine is added as chlorine gas or sodium/cal-cium hypochlorite to the water. The reaction of chlorine in water produces hypochlor-ous acid and hydrochloric acid ... 

Monochloramine is a more effective oxidizing agent than di- and trichtoramines. In potable water systems, monochloramine is often the predominant species present. Combined chiorine is iess aggressive, more persistent, and reacts more stowty with oxi-dizable materiats and bacteria (3). Some utilities prefer chloramines over free chlorine for disinfection because it has a lower potential to form THMs and has tess taste and odor probtems. Atso, it travets further in the typical distribution system. 

Chloramine reactions do not release COj gas or destroy the integrity of the carbon. However, chloramine reactions are much slower than chlorine reactions with activated carbon. Finally, although carbon can effectively remove chlorine from potable water, it is more expensive than other dechlorination methods (9,10). 

The limitations to using catalytic carbon for potable water dechlorination include (i) inability to dechlorinate free chlorine (only chloramines are removed by catalytic carbon) and (ii) potential loss of carbon life due to fouling by organic compounds or oxidation by various compounds. Furthermore, catalytic carbons are generally more expensive than activated carbon as well as other dechlorination methods currently available. 

AN EXAMINATION OF THE RELATIVE IMPACT OF COMMON POTABLE WATER DISINFECTANTS (CHLORINE, CHLORAMINES AND CHLORINE DIOXIDE) ON PLASTIC PIPING SYSTEM COMPONENTS... 

The three most eommon disinfectants in potable water are ehlorine, chloramines and chlorine dioxide. While these disinfectants are all oxidants, their uniqne eharacteristics can residt in a significantly different impact on the performance of plnmbing system components. In this paper, the chemistry and characteristics of the oxidants are discussed in the context of oxidative degradation of plastic piping system components. Testing strategies to ensure material performance in potable water applications are presented and reviewed. 

S. Chung, K. Oliphant, P. Vibien and J. Zhang, An Examination of the Relative Impact of Common Potable Water Disinfectants (Chlorine, Chloramines and Chlorine Dioxide) on Plastic Piping System Components, PPXIII, Washington D.C. (2006). 

The production of glyphosate herbicide (Round-up), the world s most successful herbicide, is another example of utilization of the catalytic properties of carbon surfaces [338], The Monsanto process by which Round-up is produced uses activated carbon as an oxidation catalyst for one of the key synthesis steps. The catalyst is produced by the treatment of activated carbon with ammonia at a high temperature to impart the desired nitrogen functionality. These functionalities are also commercially important for the reduction of chloramine in potable (drinking) water. Since water utilities are increasingly using chloramine rather than chlorine for water disinfection, and standard activated carbon products are not effective for removal of residual chloramine (which, for example, is highly toxic to dialysis patients), a catalytic carbon must be used to reduce its content [339,340],... 

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