Drinking Water Drinking Water Treatment Treatment
Mar 19, 2016
Drinking Water Drinking Water TreatmentTreatment
The Safe Drinking The Safe Drinking Water Act (SDWA)Water Act (SDWA)
Originally passed in Originally passed in 19741974
Federal law that Federal law that ensures the quality of ensures the quality of Americans’ drinking Americans’ drinking waterwater
EPA sets standards for EPA sets standards for drinking water qualitydrinking water quality MCLGMCLG MCLMCL
How do we treat our How do we treat our water in order to make water in order to make
it safe to drink??it safe to drink?? After aeration, the water treatment After aeration, the water treatment process can be divided into 4 main process can be divided into 4 main steps:steps:
Coagulation & FlocculationCoagulation & Flocculation
SedimentationSedimentation
FiltrationFiltration
DisinfectionDisinfection
Now, let’s look at each step
more in-depth!
AeratioAerationn
This is considered to be the very This is considered to be the very 11stst step in the treatment process. step in the treatment process.
Aeration refers to the addition of Aeration refers to the addition of air to the water.air to the water. This allows gases trapped in the This allows gases trapped in the
water to escape & adds oxygen to water to escape & adds oxygen to the water.the water.
Coagulation Coagulation & Flocculation& Flocculation
Coagulation removes dirt and other Coagulation removes dirt and other particles suspended in water. particles suspended in water.
Alum (aluminum potassium sulfate) Alum (aluminum potassium sulfate) and other chemicals are added to water and other chemicals are added to water to form tiny sticky particles called "floc" to form tiny sticky particles called "floc" which attract the dirt particles. which attract the dirt particles.
The combined weight of the dirt and The combined weight of the dirt and the alum (floc) become heavy enough to the alum (floc) become heavy enough to sink to the bottom during sink to the bottom during sedimentation.sedimentation. http://techalive.mtu.edu/meec/demo/Flocculation.html
SedimentationSedimentation The heavy particles (floc) settle to The heavy particles (floc) settle to
the bottom.the bottom.
Water must remain in the tank for a Water must remain in the tank for a long period to allow the floc to settle long period to allow the floc to settle out.out.
Then, the clear water moves to Then, the clear water moves to filtration.filtration. http://techalive.mtu.edu/meec/demo/Sedimentation.html
FiltrationFiltration The water passes through filters, The water passes through filters,
some made of layers of sand, some made of layers of sand, gravel, and charcoal that help gravel, and charcoal that help remove even smaller particles. remove even smaller particles.
http://techalive.mtu.edu/meec/demo/Filtration.html
DisinfectionDisinfection A small amount of chlorine is A small amount of chlorine is
added or some other disinfection added or some other disinfection method is used to kill any method is used to kill any bacteria or microorganisims that bacteria or microorganisims that may be in the water. may be in the water.
http://techalive.mtu.edu/meec/demo/Disinfection.html
Overview…Overview…
Animation on EPA Animation on EPA WebsiteWebsite Go to Go to
http://www.epa.gov/OGWDW/kids/tehttp://www.epa.gov/OGWDW/kids/teachers_9-12.htmlachers_9-12.html
Click on “Interactive Water Click on “Interactive Water Filtration Instructions”Filtration Instructions”
When prompted, click on the When prompted, click on the bottom of the screen to startbottom of the screen to start
Then, click on 3 “How to Complete Then, click on 3 “How to Complete the Lesson” and watch the the Lesson” and watch the animation.animation.
As you watch, please write down As you watch, please write down each step in the treatment process.each step in the treatment process.
SDWA (continued)SDWA (continued) Maximum Contaminant Level Maximum Contaminant Level
Goal (MCLG) Goal (MCLG) A level for substances found in A level for substances found in
drinking water set by the EPA and drinking water set by the EPA and based on health effectsbased on health effects
Maximum Contaminant Level Maximum Contaminant Level (MCL)(MCL) Legal limit (max) of a pollutant Legal limit (max) of a pollutant
that’s allowed in drinking waterthat’s allowed in drinking water Often MCLG & MCL are sameOften MCLG & MCL are same
SDWA (continued)SDWA (continued) The EPA regulates over 80 The EPA regulates over 80
inorganic (ex: lead, mercury, & inorganic (ex: lead, mercury, & fluoride) and organic chemicals fluoride) and organic chemicals (ex: pesticides) found in drinking (ex: pesticides) found in drinking water.water.
Requires water suppliers to test Requires water suppliers to test water for regulated substances.water for regulated substances.
If they exceed legal limits, they If they exceed legal limits, they must make adjustments.must make adjustments.