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Chlorine vs. Chloramine for Water Disinfection
What is chloramine?
Chloramines (NH2Cl)
are formed when there is a reaction between free chlorine (Cl2)
and
ammonia (NH3). The ideal pH for the reaction is
8.4, making the water
slightly alkaline. Chloramines may be used
as bleach, disinfectants or oxidators.
Using Chloramines for the Disinfection of Water
To disinfect water using
chloramines, ammonia is added to previously chlorine-treated water.
Municipal water treatment systems are beginning to make the switch from
using chlorines to using chloramines instead, for the disinfection of
water. Here are the pros and cons of using chloramine instead of
chlorine:
Pros
- Using
chlorine as a disinfectant results in the production of trihalomethanes
(THM) and other carcinogenic byproducts. Few are formed when
chloramines are used.
- Chloramines remain active in water for longer than
chlorine, ensuring safety from waterborne pathogens for a
longer period of time. Chlorine dissipates once it has been boiled, or
exposed to air for an extended period.
- Many
people choose to filter water that has been disinfected with chlorine,
because of the bad taste and odor that chlorine leaves behind. However,
chloramines improve the taste and smell of water.
Cons
- Using chloramine as a disinfectant often results in the
formation
of organic chloramines. These form when there is a large amount of
organic material (>3ppm) present in the water. Organic
chloramines are less
effective at disinfection than inorganic chloramines.
- Chloramine is less reactive than chlorine, requiring a
longer reaction time for effective disinfection. Part of the
disinfectant remains in the water to be
consumed by bacteria or broken down, a process which can take
weeks.
- While chlorine perishes when water lies still for a few
days,
chloramines
do not and must be removed from the water instead, using granular
activated carbon or acetic acid.
- Chloramines may be less effective than chlorine for the
removal of pathogens, even though the EPA claims that they
are as effective.
Any studies refuting the EPA's claims have not been published.
- High
amounts of ammonia in water can cause nitrate levels to rise. Nitrates
cause the oxygen level in the blood to fall and can be
carcinogenic.
- When chloramines are removed, ammonia may be
released. Ammonia causes corrosion of lead and copper, of which most
water pipes are made. (Orthophosphates may be added to reduce
corrosion.)
- Adding
chloramine to the water supply can increase exposure to lead, due to
the corrosion of lead pipes, resulting in increased lead levels in the
bloodstream, which can pose a significant health risk.
- Exposure to
chloramines may also cause respiratory problems, including asthma,
especially in swimmers - if it is used in swimming pools. Chloramines
may also
have an effect on the lungs, if inhaled during a hot shower.
- Like chlorine, chloramines are toxic to fish and cannot be
used in aquarium water.
Removing Chloramines From Drinking Water
It appears that the disadvantages of disinfecting water with chloramine
outweigh the advantages. Even though they improve the taste and odor of
water, many people still choose to remove it, because of the potential
carcinogenic effects. Chloramines can be
removed by special type of granular active carbon filter,
designed specifically for chloramine removal. Chloramines are difficult
to remove by
reverse osmosis filtration. Contact time is significant for the removal
of
chloramines from water. The longer the water is in contact with the
filter, the more contaminants are removed. Filters Fast carries several
types of chlorine and chloramine water filters.
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