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Chlorination
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The process in water treatment of adding chlorine (gas or solid
hypochlorite) for purposes of disinfection.
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Disinfection
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The treatment of water to inactivate, destroy, and/or remove pathogenic
bacteria, viruses, protozoa, and other parasites.
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Pre-Chlorination
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The addition of chlorine to the water prior to any other plant treatment
processes.
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Disinfection
By-Products
(DBPs)
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The products created due to the reaction of chlorine with organic
materials (e.g. leaves, soil) present in raw water during the water
treatment process.
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Trihalomethanes
(THMs)
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The most common class of disinfection by-products created when chemical
disinfectants react with organic matter in water during the disinfection
process.
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Turbidity
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The measure of small particles (e.g. soil, sand) of solid matter
suspended in water.
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Enhanced
Coagulation
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The process of joining together particles in water to help remove
organic matter.
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Flocculation
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The process of bringing together destabilized or coagulated particles
to form larger masses which can be settled and/or filtered out of
the water being treated.
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Sedimentation
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The process of suspended solid particles settling out (going to
the bottom of the vessel) in water.
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Filtration
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A water treatment step used to remove turbidity, dissolved organics,
odor, taste and color.
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Residual
disinfection/
Protection
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A required level of disinfectant that remains in treated water to
ensure disinfection protection and prevent recontamination throughout
the distribution system (i.e., pipes).
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Organic
Precursors
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Natural or man-made compounds with chemical structures based upon
carbon that, upon combination with chlorine, lead to trihalomethane
formation.
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Alternative
Disinfectants
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Disinfectants - other than chlorination - used to treat water, e.g.
ozone, ultraviolet radiation, chlorine dioxide, and chloramine.
There is limited experience and scientific knowledge about the by-products
and risks associated with the use of alternatives.
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Maximum
Contaminant
Levels (MCL)
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The highest permissible level of a microbial or chemical contaminant
allowed in water that is delivered to the consumer's tap.
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Waterborne
Diseases
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A disease, caused by a virus, bacterium, protozoan, or other microorganism,
capable of being transmitted by water (e.g., typhoid fever, cholera,
amoebic dysentery, gastroenteritis).
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Microbial
Contaminants
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Microscopic organisms present in untreated water that can cause
waterborne diseases.
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Infectious
Pathogens/
Microbes/Germs
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Disease-producing bacteria, viruses and other microorganisms.
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