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By Alex
Silbajoris
Water treatment for
health and safety is usually done with chlorine because chlorine kills
microorganisms that are responsible for waterborne diseases like typhoid fever
and cholera.
But some water uses,
such as aquarium-keeping or home brewing, require chlorine-free water and many
people prefer to drink water without the distinctive chlorine aroma and flavor.
Remove Chlorine by
Evaporation
Chlorine is a gas at
room temperature, and in water it's a "volatile solute" meaning its
molecules are diffused in the water, and it will escape into the air over time.
The amount of time
needed varies with air and water temperature. Heating or boiling the water will
speed the process.
Another factor is the
amount of surface area for the volume of water; a wide-mouth container will
allow the chlorine to dissipate more quickly because it exposes more of the
water's surface to the air.
This method will only
remove chlorine, though, and many modern water treatment systems use
chloramines.
You cannot rely on
evaporation to remove chloramines, so if you are changing a fish bowl, check
with your water department to see if they use chloramines.
If they do, you will
need to use a different method to ensure safe water for your fish.
Remove Chlorine by
Filtration
Chlorine can be
removed by running the water through a filter with activated charcoal, in
granular or particle form.
The carbon works by
adsorption, the molecular bonding of the chlorine ions to the surface of the
charcoal.
According to the
Minnesota Department of Health, it's important to size the filter(s)
appropriately for the amount of water to be treated, and the charcoal must be
replaced periodically.
Another filtering
method is kinetic degradation fluxion: using a copper-zinc alloy to convert
free chlorine to chloride through oxidation.
To remove chloramine,
an extensive carbon filter (to remove the chlorine part of the chloramine
molecule) followed by a reverse osmosis or cation filter (to remove the
ammonia) is necessary.
Remove Chlorine
Through Chemical Neutralization
Several chemical
compounds can remove chlorine from water. Some, like sulfur dioxide, are toxic
and dangerous to handle.
Others, like ascorbic
acid, or vitamin C, are safer, or even edible. Other options include sodium
thiosulfate, sodium sulfite, or sodium bisulfite.
The resulting
by-products vary, and in some cases -- discharging dechlorinated water into
streams, for example -- environmental regulations may apply because of
consequences like reduced dissolved oxygen in receiving streams. This is called
"oxygen scavenging."
Again, if you are
trying to purify your water for applications like fish tanks, check if your
drinking water is treated with chloramines, and if so, you will need different
chemicals for neutralization.
Remove Chlorine
dioxide
Chlorine dioxide is a
water additive used to control microbes and can be used to control tastes and
odors. It rapidly disappears from stored water.
An
ecological blogger, technical writer and trainer, Alex Silbajoris also
leads a nonprofit watershed group. He is an avid gardener and cook. He holds a
bachelor's degree in English and a master's degree in journalism, from The Ohio
State University. Other studies include geology and biological sciences.
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