Chloramination
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Chloramination is the treatment of drinking water with a chloramine disinfectant. Both chlorine and small amounts of ammonia are added to the water one at a time which react together to form chloramine (also called combined chlorine), a long lasting disinfectant. Chloramine disinfection is used in both small and large water treatment plants.
Chloramination is the treatment of drinking water with a chloramine disinfectant. Both chlorine and small amounts of ammonia are added to the water one at a time which react together to form chloramine (also called combined chlorine), a long lasting disinfectant. Chloramine disinfection is used in both small and large water treatment plants.
Removing monochloramine from water
Chloramines should be removed from water for dialysis, aquariums, hydroponic applications, and homebrewing beer. Chloramine must be removed from water prior to use in kidney dialysis machines because it can cause hemolytic anemia if it enters the blood stream. In hydroponic applications, chloramine stunts the growth of plants. When a chemical or biological process that changes the chemistry of chloramines is used, it falls under reductive dechlorination. Other techniques use physical—not chemical—methods for removing chloramines.
Ultraviolet light
The use of ultraviolet light for chlorine or chloramine removal is an established technology that has been widely accepted in pharmaceutical, beverage, and dialysis applications. UV is also used for disinfection at aquatic facilities.
Ascorbic acid and sodium ascorbate
Ascorbic acid (vitamin C) and sodium ascorbate completely neutralize both chlorine and chloramine, but degrade in a day or two, which makes them usable only for short-term applications. SFPUC determined that 1000 mg of vitamin C tablets, crushed and mixed in with bath water, completely remove chloramine in a medium-size bathtub without significantly depressing pH.
Activated carbon
A 2013 study by the University of Texas at Austin shows that activated carbon removed efficiency up to nearly 90% monochloramine using a 0.75-minute empty bed contact time In 2021, the Royal Society of Chemistry's study concluded that both ozonation and granular activated carbon was successful in reducing monochloramine. Activated carbon has been used for chloramine removal long before catalytic carbon, a form of activated carbon, became available ; standard activated carbon requires a very long contact time, which means a large volume of carbon is needed. For thorough removal, up to four times the contact time of catalytic carbon may be required. Most dialysis units now depend on granular activated carbon (GAC) filters, two of which should be placed in series so that chloramine breakthrough can be detected after the first one, before the second one fails. Additionally, sodium metabisulfite injection may be used in certain circumstances.
Campden tablets
Home brewers use reducing agents such as sodium metabisulfite or potassium metabisulfite (both proprietorially sold as Campden tablets) to remove chloramine from brewing fermented beverages. However, residual sulfite can cause off flavors in beer so potassium metabisulfite is preferred.
Sodium thiosulfate
A 2022 per-reviewed study published by the Journal of Emerging Supply Chain Clean Energy and Process Engineering demonstrated that sodium thiosulfate is able to reduce chlorine residue by up to 0.4 ppm. Sodium thiosulfate is used to dechlorinate tapwater for aquariums or treat effluent from wastewater treatments prior to release into rivers . The reduction reaction is analogous to the iodine reduction reaction. Treatment of tapwater requires between 0.1 and 0.3 grams of pentahydrated (crystalline) sodium thiosulfate per 10 L of water . Many animals are sensitive to chloramine, and it must be removed from water given to many animals in zoos.
Other methods
Chloramine, like chlorine, can be removed by boiling and aging. However, time required to remove chloramine is much longer than that of chlorine. The time required to remove half of the chloramine (half-life) from of water by boiling is 26.6 minutes, whereas the half-life of free chlorine in boiling 10 gallons of water is only 1.8 minutes. Aging may take weeks to remove chloramines, whereas chlorine disappears in a few days.
References
Text derived from https://en.wikipedia.org/w/index.php?oldid=1366335521 under CC BY-SA 4.0; modifications have been made.