Disinfection chlorination

Disinfection. Chlorine, as gaseous chlorine or as the hypochlorite ion, is widely used as a disinfectant. However, its use in some cases can lead to the formation of toxic organic chlorides and the discharge of excess chlorine can be harmful. Hydrogen peroxide and ozone are alternative disinfectants that lead to products that have a lower toxic potential. Treatment is enhanced by ultraviolet light. Indeed, disinfection can be achieved by ultraviolet light on its own. 

Since hypochlorous acid is a powerful disinfectant, chlorine is widely used to render municipal water safe for drinking. 

Disinfectants chlorine, ozone, chloramine, chlorine dioxide, and their byproducts. 

In addition to regular disinfection procedures, cooling systems (and especially the towers) should always be cleaned and disinfected (chlorinated)... 

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. 

Comparing the diagram in Fig. 7-5 with those developed for the other halogens (Fig. 7-6) used as water disinfectants, chlorine and iodine, we... 

Uses Solvent, cosolvent, compatibilizer, coupling agent, processing aid for pharmaceuticals, personal care prods., aq. coatings and adhesives, agric. formulations, polymer processing, cleaners/disinfectants chlorinated hydrocarbon stabilizer... 

Since the initial observation on the occitrrence and formation of THMs, additional research has shown that all chemical disinfectants (chlorine, monochloramines, ozone, and chlorine dioxide) can form various types of disinfection byproducts (DBFs). 

Chemical unit operations Chemical precipitation Adsorption Disinfection Chlorination Other chemical apphcations... 

Lee W, Westerhoff P (2009) Formation of organic chloramines during water disinfection - chlorination versus chloramination. Water Res 43(8) 2233-2239... 

A high content of elemental chlorine in the product may require its purification to prevent unwanted side reactions from CI2. As a water disinfectant, chlorine dioxide does not chlorinate or oxidize ammonia or other nitrogen-containing compounds. 

The toxicity of chlorine is a significant factor regarding its use for water disinfection. Chlorine is so toxic when it is inhaled that it was the first poison gas used in World War 1. Elemental chlorine can be stored and transported as a liquid under pressure. Released to the atmosphere, it forms a dense layer of choking gas that reacts in moist respiratory tract tissue to produce acid and tissue-damaging oxidants. Levels of 10-20 ppm in air can cause immediate damage to the respiratory tract and a brief exposure to air containing 1000 ppm of chlorine can be fatal. 

Waste water chlorination is even older than drinking water chlorination. It makes use of the toxicological, oxidative and coagulant properties of chlorine. Besides the main target, the disinfection, chlorine is used to deodorize the waste water, e.g in presence of hydrogen sulfides, to decolorize, to retard putrefaction, to reduce the biochemical oxygen demand (BOD), and to ease the filtration by improved coagulation. 

Other organic chloroamines serve as bactericides, disinfectants, chlorinating agents in organic synthesis, and bleaching agents. 

Children who regularly swim in indoor swimming pools have been found to have higher rates of asthma than those who do not. The cause has been attributed to the reaction of disinfectant chlorine (hypochlorous acid) with organic matter (e.g., perspiration, saliva, and urine) to produce lipophilic/hydrophilic mixtures of disinfection by-products that include THMs, trihaloacetic acids, and chloramines that are inhaled by swimmers as vapors and aerosols [63]. Similar inCTeases in asthma prevalence have been reported for lifeguards who work in indoor swimming pools [64]. 

---